10.7-Gb/s Discrete Multitone Transmission Over 25-m Bend-Insensitive Multicore Polymer Optical Fiber - Loquai, Sven; Kruglov, R.; Bunge, C.-A.; Ziemann, O.; Schmauß, Bernhard (IEEE Photonics Technology Letters, 2010)
lhft_intern.bib::Loquai10

10.7-Gb/s Real-Time Transmission Over 1-mm Large-Core Polymer Optical Fiber Using Maximum Likelihood Sequence Estimation - Loquai, Sven; Noelscher, Thomas; Bunge, Christian-Alexander; Kupfer, Theodor; Winkler, Florian; Hartl, Engelbert; Schmauß, Bernhard (IEEE Photonics Technology Letters, 2012)
We report 10.7-Gb/s nonreturn-to-zero (NRZ) real-time transmission over a 1-mm large-core polymethylmetacrylate polymer optical fiber (POF) using maximum likelihood sequence estimation. A maximum link length of 10 m of a standard step-index POF (SI-POF) and 35-m graded-index POF (GI-POF) was achieved with a fiber coupled power of 0 dBm, in order to comply with consumer eye-safety regulations. In order to show the robustness of this approach, the influence of fiber bends and different launching conditions were investigated. If the optical output power is increased to the link length can be increased up to 40 m of GI-PO
lhft_intern.bib::Loquai2012xx

10 Gbit/s Short Range Transmission over 35 m Large-core Graded-Index Polymer Optical Fiber - Kruglov, R.; Loquai, Sven; Bunge, C.-A.; Ziemann, O.; Schmauß, Bernhard (Optical Fiber Communication 2011, 2011)
lhft_intern.bib::Kruglov11

10-Gb/s Pulse-Amplitude Modulated Transmission Over 1-mm Large-Core Polymer Optical Fiber - Loquai, Sven; Kruglov, Roman; Bunge, Christian-Alexander; Ziemann, Olaf; Schmauß, Bernhard (IEEE Photonics Technology Letters, 2012)
The authors report on a 10-Gb/s transmission over 1-mm large-core diameter polymer optical fiber (POF) using pulse-amplitude modulation. For the first time, a real-time 10-Gb/s eye-diagram is shown after 5-m standard step-index POF (SI-POF), even with an eye-safe transmitter (0 dBm). With an offline decision feedback equalization technique, a link length of 10-m SI-POF, respectively, 25-m GI-POF was achieved. With a slightly higher optical power of +5 dBm, the maximum link length could even be increased to 30-m SI-POF and 60-m GI-PO
lhft_intern.bib::Loquai2012

12dB of noise reduction by a NOLM based 2-R regenerator - Schmauß, Bernhard; Rösch, Matthias; et al. (IEEE Photonics Technology Letters, 2003)
UnivIS-Import:2015-03-09:Pub.2003.nat.dphy.optik.1optik.12dbof

12 dB of Noise Reduction by a NOLM based all optical all passive Regenerator - Meißner, Markus; Rösch, Matthias; Schmauß, Bernhard; Leuchs, Gerd (CLEO Europe, June, 2003)
UnivIS-Import:2015-04-16:Pub.2003.tech.IE.LEH.12dbof_5

160 Gbit/s Clock Recovery With Electro-Optical PLL Using a Bidiretionally Operated Electroabsorption Modulator as Phase Comparator - Börner, C.; Schubert, C.; Schmidt, C.; Hilliger, E.; Marembert, V.; Berger, J.; Ferber, S.; Dietrich, E.; Ludwig, E.; Schmauß, Bernhard; Weber, H. G. (Conf. Proc. OFC, Paper FF3, 2003)
UnivIS-Import:2015-04-16:Pub.2003.tech.IE.LEH.160gbi

160 Gbit/s DPSK Transmission over 410 km Dispersion-Managed Fiber - Ludwig, R.; Ferber, S.; Schubert, C.; Börner, C.; Beling, A.; Bach, H.G.; Schmauß, Bernhard; Wietfeld, André; Berger, J.; Schmidt, C.; Weber, H. G. (Conf. Proc. NOC, 2003)
UnivIS-Import:2015-04-16:Pub.2003.tech.IE.LEH.160gbi_2

160 Gbit/s Field Transmission over 116 km Standard Single Mode Fiber Using 160 Gbit/s OTDM and 40 Gbit/s ETDM Demultiplexer - Feiste, U.; Ludwig, R.; Schubert, C.; Berger, J.; Schmidt, C.; Weber, H. G.; Rumpf, F.; Schmauß, Bernhard; et al. (IEE Proceedings Optoelectronics, 2001)
T. Systems Nova, Technologiezentrum, the first 160 Gbit/s RZ transmission experiment over field-installed standard fibre G.652 is reported. The transmitter rests upon the OTDM technique. At the receiver, a 160 Gbit/s to 40 Gbit/s OTDM demultiplexer followed by 40 Gbit/s electrical signal processing (ETDM) is used. The results are compared with 160 Gbit/s to 10 Gbit/s OTDM demultiplexing experiments. The OTDM demultiplexer is based on cross phase modulation in a semiconductor optical amplifier.
UnivIS-Import:2015-03-09:Pub.2001.tech.IE.LEH.160gbi_1

160 Gbit/s Transmission over 116 km Field-Installed Fiber Using 160 Gbit/s OTDM and 40 Gbit/s ETDM - Feiste, U; Ludwig, R; Schubert, C; Berger, J; Schmidt, C; Weber, H; Schmauß, Bernhard; Munk, A; Buchold, B; Kueppers, F; Rumpf, F (Conf. Proc. OFC, Paper ThF3, March, 2001)
lhft_intern.bib::feiste01b

160 Gbit/s Transmission over 116 km Field-Installed Fiber Using 160 Gbit/s OTDM and 40 Gbit/s ETDM - Feiste, U.; Ludwig, R.; Schubert, C.; Berger, J.; Schmidt, C.; Weber, H. G.; Schmauß, Bernhard; Munk, A.; Buchold, B.; Briggmann, D.; Küppers, F.; Rumpf, F. (Electronics Letters, 2001)
We report the first 160 Gbit/s RZ transmission experiment over field-installed standard fiber G.652 with optical 160 Gbit/s to 40 Gbit/s demultiplexing (OTDM) and subsequent electrical signal processing (ETDM) and we compare these results with 160 Gbit/s to 10 Gbit/s OTDM demultiplexing experiments.
UnivIS-Import:2015-03-09:Pub.2001.tech.IE.LEH.160gbi

160 Gbit/s Transmission Systems - Schmauß, Bernhard (Conf. Proc., SODC, 2002)
lhft_intern.bib::Schmauss02

160 Gbit/s Übertragung, Conf. Proc. - Schmauß, Bernhard (8. ITG Fachtagung Kommunikationskabelnetze, 2001)
UnivIS-Import:2015-04-16:Pub.2001.tech.IE.LEH.160gbi_7

24 GHz CMOS Transceiver and Wireless Sensor Network for Indoor Localization - Ebelt, Randolf; Shmakov, Denys; Hamidian, Amin; Böck, Georg; Vossiek, Martin (RFIC 2013 Workshop on Radio Frequency Systems for Indoor Localization, 2013)
UnivIS-Import:2015-04-16:Pub.2013.tech.IE.LEH.24ghzc

24 GHz CMOS Transceiver with Novel T/R Switching Concept for Indoor Localization - Hamidian, Amin; Ebelt, Randolf; Shmakov, Denys; Vossiek, Martin; Zhang, Tao; Subramanian, Viswanathan; Boeck, Georg (IEEE Radio Frequency Integrated Circuits Symposium (RFIC) 2013, 2013)
This paper presents a 130 nm CMOS transceiver for 24 GHz wireless indoor localization. Due to a novel Rx/Tx switching concept RF-losses between receiver/ transmitter and antenna could be reduced and the T/R isolation was drastically improved. The measured transceiver chip achieves an output power and noise figure of >5 dBm and <6 dB, respectively with 2 mm2 total chip size. The complete transceiver consumes 16 mW in the Rx- and 26 mW in the Tx-mode. The RF-transceiver-chip was integrated with a DSP-unit and mounted on a PCB for wireless indoor localization demonstration. The measured results show a distance measurement precision in the cm-range. © 2013 IEE
UnivIS-Import:2015-04-16:Pub.2013.tech.IE.LEH.24ghzc_4
Keywords: 130 nm CMOS; 24 GHz transceiver; localization; secondary radar

24 GHz Short-Range Microwave Sensors for Industrial and Vehicular Applications - Heide, Patric; Vossiek, Martin; Nalezinski, Martin; Oreans, L.; Schubert, R.; Kunert, M. (Proc. Workshop on Short Range Radar, 1999)
UnivIS-Import:2015-04-16:Pub.1999.tech.IE.LEH.24ghzs

2, 5 THz Open Structure Corner Cube Mixer with Substrateless Schottky Diodes - Huber, K; Hillermeier, R; Brand, Hans; Simon, A; Lin, C; Rodriguez-GiroNes, M; Hartnagel, H (1997)
lhft_intern.bib::thirty_years_LHFT_408

26.75 Gb/s Short-Reach Transmission over up to 15 m of large-core PMMA Polymer Optical Fiber for Next-Generation 100 GbE - Loquai, Sven; Winkler, F.; Kruglov, R.; Vinogradov, J.; Bunge, C. A.; Ziemann, O.; Schmauß, Bernhard; Hartl, E. (Proceedings of the Optical Fiber Communication Conference (OFC), 2013)
We demonstrate for the first time 26.75 Gb/s transmission over up to 15 m of large-core 500 μm PMMA POF. Simple NRZ modulation is used which reduces complexity, power consumption and latency of the system. In combination with a POF ribbon cable this approach is a promising and robust alternative to high-speed 100 Gb/s copper interconnects for data center applications (4 channels with 25 Gb/s each). © 2013 OS
UnivIS-Import:2015-04-16:Pub.2013.tech.IE.LEH.2675gb

2D transmission imaging with a crossed-array configuration for defect detection - Koch, Andreas; Gruber, Stefan; Scharrer, Thomas; Fendt, Karl; Lerch, Reinhard; Ermert, Helmut (2012 IEEE International Ultrasonics Symposium Proceedings, 2012)
Two-dimensional time of fight and attenuation measurements offer unique opportunities in nondestructive ultrasound testing for defect detection. However, unavailability or costs for 2D matrix transducers usually require a mechanical scanning procedure with a single element transducer to acquire 2D projections. This time and cost intensive process is not applicable for high speed testing of e.g. low cost devices. We propose a concept of a crossed-array configuration for 2D transmission imaging in terms of time of fight and attenuation measurements. A mechanical setup and a data acquisition system have been developed to evaluate the potential of this concept. Our results show, that ultrasound crossed-array transmission imaging has a great potential in terms of time of fight and attenuation measurements for defect detection in non-destructive testing, e.g. for detection of delaminations. With an appropriate data acquisition system transmission images can be acquired with frames rates in the kHz range. Therefore, crossed-array transmission imaging is a unique, cost efficient procedure with a good resolution for high speed testing in industrial applications. © 2012 IEE
Keywords: 2D projection; attenuation; crossed-array; speed of sound; time of fight; transmission imaging; ultrasound transmission

2R-Regeneration of an 80-Gb/s RZ-DQPSK signal by a nonlinear amplifying loop mirror - Cvecek, Kristian; Sponsel, Klaus; Ludwig, R.; Schubert, C.; Stephan, Christian; Onishchukov, Georgy; Schmauß, Bernhard; Leuchs, Gerd (IEEE Photonics Technology Letters, 2007)
The performance of a nonlinear amplifying loop mirror as a 2R-regenerator for an 80-Gb/s return-to-zero differential-quadrature-phase-shift-keyed signal has been investigated experimentally. A significant eye-opening improvement and a negative power penalty of up to 2.6 dB were obtained. © 2007 IEEE.
UnivIS-Import:2015-03-09:Pub.2007.nat.dphy.optik.1optik.2rrege
Keywords: 2R-regeneration; All-optical regeneration; Differential quadrature phase-shift keying (DQPSK); Nonlinear amplifying loop mirror (NALM)

2R-Regeneration of an RZ-DPSK Signal Using a Nonlinear Amplifying Loop Mirror - Cvecek, K; Sponsel, K; Onishchukov, G; Schmauß, Bernhard; Leuchs, Gerd (IEEE Photonics Technology Letters, 2007)
The performance of a nonlinear amplifying loop mirror as a 2R-regenerator for return-to-zero differential-phase-shift-keyed signals has been investigated experimentally. The measured power characteristics and phase functions show that the signal amplitude is regenerated while the signal phase is preserved in the setup. A significant eye-opening improvement and a negative power penalty of about 1.5 dB were obtain
lhft_intern.bib::cvecek07

360° Carrier Phase Measurement for UHF RFID Local Positioning - Miesen, Robert; Parr, Andreas; Schleu, Jochen; Vossiek, Martin (2013 IEEE International Conference on RFID Technologies and Applications, 2013)
Carrier phase measurement in RFID and other wireless communication devices can be used in general for ranging, angle of arrival detection and localization. Modern ISO 18000-6C RFID readers perform fully coherent demodulation, detect the signal phase and deliver it to the user. However the presented phase is π-periodical and not 2π. This is caused by the symmetry of the received signal and the phase-recovery methodology used. In this paper we introduce a phase-recovery method retrieving a 2π-periodical phase. A larger ambiguity range for the phase measurement is beneficial for all phase-based localization methods: it allows, for example, increased array-element spacing in angle-of-arrival detection methods; and improves the resolution for imaging methods. © 2013 IEEE.
UnivIS-Import:2015-04-16:Pub.2013.tech.IE.LEH.360car
Keywords: demodulation; phase measurement; position measurement; radiofrequency identification; RFID tags

3.9-dB OSNR Gain by an NOLM-Based 2-R Regenerator - Meißner, Markus; Sponsel, Klaus; Cvecek, Kristian; Benz, S.; Weisser, B.; Schmauß, Bernhard; Leuchs, Gerd (IEEE Photonics Technology Letters, 2004)
We experimentally demonstrate bit-error-rate (BER) improvement of more than nine decades by an asymmetric nonlinear optical loop mirror (NOLM). This can be related to an optical signal-to-noise ratio (OSNR) gain of up to 3.9 dB with respect to the NOLM input OSNR at a bit rate of 40 GB/s. The principle of operation of NOLM-based 2-R regeneration with respect to BER improvement is investigated and it is experimentally shown that BER improvement cannot be detected directly at the regenerator's output. © 2004 IEEE.
UnivIS-Import:2015-03-09:Pub.2004.nat.dphy.optik.1optik.39dbos

3D Millimeterwellen-Abbildung von dielektrischen Probek?rpern und numerische Rekonstruktion der Materialeigenschaften - Gumbmann, Frank; Weinzierl, Jochen; Tran, Hue Phat; Schmidt, Lorenz-Peter (DGZfP-Jahrestagung Mai, 2007)
UnivIS-Import:2015-04-16:Pub.2007.tech.IE.LEH.3dmill

3D-Printed 3 dB Hybrid Coupler for D-Band Applications - Lomakin, Konstantin; Klein, Laura; Sippel, Mark; Helmreich, Klaus; Gold, Gerald (2020 50th European Microwave Conference (EuMC), 2021)
In this work, an additively manufactured 3 dB hybrid coupler for the D-Band frequency range is presented. The plastic body is printed from UV-curable polymer resin with a conventional desktop DLP printer and subsequently functionalized by an electroless silver plating process. The slotted waveguide approach is used, in order to improve the metal coating and enable the implementation of complex waveguide structures. Measured isolation and matching range at -15 dB while the asymmetry in magnitude between coupling and through port remains below 0.8 dB over the frequency range from 115 to 154 GHz, yielding an operational relative bandwidth of almost 28 % and hence, suggesting general feasibility for directional coupling applications. Measured phase differences deviate from the desired 90° by 40° to 50° which is related to the overall tolerances with respect to absolute geometrical dimensions of conventional desktop DLP printers and required post processin

3D-Printed Bowtie Filter Created by High Precision NanoJet System Combined with Novel Printing Strategy - Sippel, Mark; Lomakin, Konstantin; Ankenbrand, Markus; Petersen, Matthias; Franke, Jörg; Helmreich, Klaus; Vossiek, Martin; Gold, Gerald (28th Conference on Electrical Performance of Electronic Packages and Systems (EPEPS 2019), 2019)
This paper focuses on the latest aerosol based printing system in conjunction with a newly developed manufacturing method. The presented novel method is successfully demonstrated on a Bowtie Filter in comparison to the same pho-tolithographically produced structure.<br

3D-Printed Compact Full-E-Band Wavemode Transitions for Direct Launching from IC to Waveguides with minimal Line Length on PCB - Lomakin, Konstantin; Alhasson, Saif; Gold, Gerald (22nd IEEE Wireless and Microwave Technology Conference, 2022)

3D Printed Copper Waveguides by Selective Electron Beam Melting Process for E-Band - Lomakin, Konstantin; Guschlbauer, R.; Osmanlic, Fuad; Fu, Zongwen; Sippel, Mark; Helmreich, Klaus; Körner, Carolin; Vossiek, Martin; Gold, Gerald (EuMW 2019, 2019)
This work evaluates 3D printed E-Band waveguides by selective electron beam melting process with two different scanning pattern approaches. One is the contouring and the other the hatching pattern which are used to draw the waveguide cross section layer wise. The measured signal attenuation can be significantly reduced to only about 11-17 dB/m in E-Band by applying the contour strategy despite the relatively large macroscopic RMS surface roughness of Rq & 30 μm. Furthermore, a model based explanation for the measured results is proposed suggesting a distinct separation between microscopic structure geometry and surface roughness for E-Band frequencies and beyond.<br

3D-Printed Dielectric Image Lines Towards Chip-to-Chip Interconnects for subTHz-Applications - Hahn, Leonhard; Pfahler, Tim; Bader, Tobias; Gold, Gerald; Vossiek, Martin; Carlowitz, Christian (2024 IEEE International Conference on Microwaves, Communications, Antennas, Biomedical Engineering and Electronic Systems, COMCAS 2024, 2024)
This paper reports on 3D-printed dielectric image lines for low-loss subTHz applications between 140 and 220 GHz. In contrast to conventional dielectric waveguides, a conductive copper substrate is used to achieve robust routing and increased mechanical stability. For easy integration and characterization of the dielectric image line within a waveguide measurement setup, a low-loss mode-converter for flexible mounting is further designed. The characterized overall system exhibits a broadband match of at least 20 dB over the entire frequency band, with minimal losses of below 0.35 dB/cm. Furthermore, multi-line characterization is performed for de-embedding the propagation parameters α and β of both the dielectric transmission line and the mode-converter, and finally, the influence of discontinuities such as bending radii on the transmission behavior is evaluated. Due to the simplicity of the underlying 3D-printing technology, the proposed concept features extremely low cost and complexity, yet offers high flexibility and outperforms the losses of conventional transmission lines.
CRIS-Team Scopus Importer:2024-10-18
Keywords: 3D-printing; Dielectric image lines; dielectric waveguide; low-loss transmission lines; subTHz distribution networks

3D Printed E-Band Hybrid Coupler - Lomakin, Konstantin; Klein, Laura; Ringel, Lorenz; Ringel, Johannes; Sippel, Mark; Helmreich, Klaus; Gold, Gerald (IEEE Microwave and Wireless Components Letters, 2019)
In this work, an additively manufactured 3dB hybrid coupler is presented. While the geometrical structure is generated by an SLA printer from UV curable photopolymer resin as one single part, conductive coating is provided by an electroless silverplating process. The utilized slotted waveguide approach improves the solvent flow during metal plating and therefore enables the fabrication of complex waveguide struc- tures. Measured imbalance between the through and coupling port stays below 1.5dB over the entire E-Band, while the respective phase difference ranges only between 87◦ and 91◦ degrees despite the challenges of additive manufacturing in such frequency regions

3D Printed Helix Antenna - Lomakin, Konstantin; Pavlenko, Tatiana; Sippel, Mark; Gold, Gerald; Weidner, T; Helmreich, Klaus; Ankenbrand, Markus; Franke, Jörg (European Conference on Antennas and Propagation (EUCAP), 2018)

3D Printed Helix Antenna for 77 GHz - Lomakin, Konstantin; Sippel, Mark; Ullmann, Ingrid; Helmreich, Klaus; Gold, Gerald (2020 14th European Conference on Antennas and Propagation (EuCAP), 2020)
In this work, an additively manufactured helix antenna for a center frequency of f c = 77 GHz is presented. A novel feed concept is proposed including a transition from the helix coil to an E-band waveguide, which allows for tuning of antenna matching. Measurements suggest a -15dB-bandwidth of B 15 dB =8 GHz and -10dB-bandwidth of B 10 dB =16 GHz respectively with a fractional -10dB-bandwidth of 20 %. An axial ratio below AR<; 5 dB is achieved within the entire B-10 dB and even AR<; 3 dB within B-15 dB in main lobe direction. The realized antenna gain ranges at G LP ≈11 dBi in linear polarization component yielding a circular polarization gain of G CP ≈12 to 13 dBi. Hence, measurements suggest general feasibility of the proposed helix antenna for mmWave applications despite the relatively high structure complexity due to the miniaturized dimensions at the aimed frequencie

3D Printed Hemispherically Radiating Antenna for Broadband Millimeter Wave Applications - Engel, Lukas; Khouri, Danti; Lomakin, Konstantin; Hofmann, Andreas; Kleinlein, Micha; Ullmann, Ingrid; Vossiek, Martin; Gold, Gerald (IEEE Open Journal of Antennas and Propagation, 2023)
Nowadays, additive manufacturing provides far-reaching possibilities for use in radio frequency components. In addition to almost unlimited freedom of design as compared to conventional manufacturing, the absence of further assembly steps is a key aspect of 3D printing. In this paper, a 3D printed monolithic antenna for millimeter wave-sensing applications is presented with a full hemispherical coverage. The antenna is designed as an ensemble of a waveguide horn antenna and a differentially fed dipole antenna. The slotted waveguide approach was utilized to improve the manufacturing quality on the waveguide inside. The influence of two optimized antenna elements, a metal plane, and a cut-out window, on the beam pattern is comprehensively investigated. A huge half power beam width of 142° in both directions, elevation and azimuth, is presented at 79 GHz and a boresight gain of 4.7 dBi was measured. The beam pattern in the frequency range from 76 to 81 GHz is studied in greater detail, where a half power beam width of at least 112° is achieved. Due to the −10 dB matching capability bandwidth of over 28 GHz, the antenna is also suitable for extremely broadband applications with a −5 dB angular width of better than 100°. Furthermore, the system design describes how to integrate the antenna into hybrid circuit designs and the manufacturing tolerances are examined. The antenna offers attractive possibilities for millimeter wave-sensing applications in the area of assisted living and industrial monitoring, especially whenever blind spots have to be avoided.<br

3D-Printed Reconfigurable Communication System Based on Tunable Liquid Crystals - Pietschmann, Simon; Shi, Jing; Bachbauer, Felix; Gold, Gerald; Maune, H. (2025 IEEE Wireless and Microwave Technology Conference, WAMICON 2025, 2025)
This paper presents an additively manufactured communication system for V-Band applications using a 2 × 2-Antenna array in which each element can be controlled by an individual liquid crystal (LC) based phase shifter. To integrate the anisotropic material into the feed structure, a cavity made of UV-curable photopolymer resin is printed using stereolithography. A targeted beam steering angle of 7° was achieved, while the measured gain of the phased antenna array was between 16.18 dB and 14.02 dB at a center frequency of 62.5 GHz.
CRIS-Team Scopus Importer:2025-06-20
Keywords: additive manufacturing; inter-satelite links; liquid crystal; phase shifter; phased antenna array

3D Printed Slotted Rectangular Hollow Waveguides - Lomakin, Konstantin; Herold, Sophie; Simon, D.; Sippel, Mark; Sion, A.; Vossiek, Martin; Helmreich, Klaus; Gold, Gerald (IEEE MTT-S International Microwave Symposium, Boston, USA, Juni, 2019., 2019)
This work proposes a fabrication approach for 3D printed waveguide paths based on a combination of an optimized electroless silver plating process with a waveguide-specific design rule for general metal plating by introducing large scale non-radiating slots into the broad and narrow waveguide walls with a periodicity shorter than quarter of the guided wavelength. Experimental fabrication of straight sections of the proposed slotted waveguide with various gap dimensions yields an optimum gap size as result of a trade-off between silver plating quality and leakage losses through the sidewall gaps Moreover, a successful practical application of the proposed approach is presented in terms of a 3D printed multiple bend waveguide interconnect in three different space dimensions which imposes a complex task for conventional manufacturing techniques due to the need of multiple cutting planes for split block assembly. The proposed approach benefits of low cost, moderate handling effort and independence of the concrete geometry to manufacture making it therefore especially interesting for distribution and feeding networks in the context of rapid prototyping, automotive and space related application

3D Printed Slotted Waveguide Array Antenna for Automotive Radar Applications in W-Band - Lomakin, Konstantin; Simon, D.; Sippel, Mark; Gold, Gerald; Helmreich, Klaus; Seler, Ernst; Tong, Z.; Reuter, R. (48th European Microwave Conference (EuMW 2018), 2018)

3D Printed Slotted Waveguide Array Antenna for D-Band Applications - Lomakin, Konstantin; Sippel, Mark; Helmreich, Klaus; Gold, Gerald (2021 15th European Conference on Antennas and Propagation (EuCAP), 2021)
In this work, an additively manufactured helix antenna for a center frequency of f c = 77 GHz is presented. A novel feed concept is proposed including a transition from the helix coil to an E-band waveguide, which allows for tuning of antenna matching. Measurements suggest a -15dB-bandwidth of B 15 dB =8 GHz and -10dB-bandwidth of B 10 dB =16 GHz respectively with a fractional -10dB-bandwidth of 20 %. An axial ratio below AR<; 5 dB is achieved within the entire B-10 dB and even AR<; 3 dB within B-15 dB in main lobe direction. The realized antenna gain ranges at G LP ≈11 dBi in linear polarization component yielding a circular polarization gain of G CP ≈12 to 13 dBi. Hence, measurements suggest general feasibility of the proposed helix antenna for mmWave applications despite the relatively high structure complexity due to the miniaturized dimensions at the aimed frequencie

3D Printed Transmission Type Phase Shifter Based on Tunable Liquid Crystals - Pietschmann, Simon; Bilchenko, F.; Maune, H.; Shi, Jing; Bachbauer, Felix; Gold, Gerald (2024 54th European Microwave Conference, EuMC 2024, 2024)
This work presents an additively manufactured transmission phase shifter operating at 60 - 65 GHz based on the relative permittivity change obtained from rotating anisotropic liquid crystals (LC) by an external field. A slotted waveguide structure is filled with a printed inlay that provides the cavity for holding the LC material. To reduce the reflection at the transition from the empty to the filled waveguide, various types of inlays are being investigated.
CRIS-Team Scopus Importer:2024-12-13
Keywords: additive manufacturing; liquid crystal; phase shifter; reconfigurable components; slotted waveguide

3D Printed Waveguide Transition for 77 GHz Radar Applications - Engel, Lukas; Lomakin, Konstantin; Gold, Gerald; Pfahler, Tim; Schür, Jan; Vossiek, Martin (Published in: 2022 14th German Microwave Conference (GeMiC), 2022)
A novel approach of a differential microstrip line to a rectangular waveguide realized by an alternative manu-facturing method, based on additive manufacturing, is presented. In comparison with conventional machining, this approach offers an improved behavior regarding weight, costs and uncomplicated alignment with simultaneous high manufacturing accuracy. The transition is designed for applications in the frequency range of 70 - 90 GHz in particular for automotive radar at 77 GHz but yet can easily be adapted for other frequencies. Measurements are carried out stating a return loss of /S11/2 < -24 dB and an insertion loss /S21/2 better than -1.3 dB at 77 GHz for the transition. To demonstrate excellent suitability for hybrid circuits an analysis of manufacturing tolerances and resulting degradation on the performance of the transition have been conducted. The measurements of this analysis prove a high reproducibility and robustness of the promising technology even for precision demanding mmW application

3D-SAR-Imaging and Thickness Determination of Zirconia Based Coatings on Non-Planar Metal Substrates in the Lower Terahertz Region - Oppelt, Daniel; Adametz, Julian; Schür, Jan; Vossiek, Martin (19th World Conference on Non-Destructive Testing, 2016)
lhft_intern.bib::Oppelt2016a

3D SAR Processing for a Fast Scanning Millimeter-Wave Short Range Imaging System - Gumbmann, Frank; Tran, Hue Phat; Weinzierl, Jochen; Schmidt, Lorenz-Peter (European Conference on Synthetic Aperture Radar (EuSAR 08,03.-05.06.08), 2008)
A fast scanning short range radar imaging system for security or non-destructive testing applications is presented. The goal was to develop an 3D-imaging system with range independent lateral resolution down to 3 mm and a range resolution down to 6 mm. Therefore a setup with non focusing antennas and a broadband (75-100 GHz) SFCW (stepped frequency continuous wave) radar module were developed. A reconstruction of the device under test (DUT) with high lateral resolution is derived by applying numerical techniques based on the synthetic aperture radar (SAR) principle. To collect as many pixels as possible over a two dimensional aperture a rotating virtual antenna was developed. It is realized by a Gaussian beam transformation of the feed antenna beam waist onto a subreflector. By rotating the quasioptical transformator, an elliptical mirror, the transformed virtual antenna is rotated as well. This scanner concept is applied to planar and cylindrical geometries.
UnivIS-Import:2015-04-16:Pub.2008.tech.IE.LEH.3dsarp

3D surface reconstruction for laparoscopic computer-assisted interventions: Comparison of state-of-the-art methods - Groch, A.; Seitel, A.; Hempel, Sarah-Marie; Speidel, S.; Engelbrecht, Rainer; Penne, Jochen; Höller, Kurt Emmerich; Röhl, S.; Yung, K.; Bodenstedt, S.; Pflaum, Felix; Dos Santos, T. R.; et al. (Medical Imaging 2011: Visualization, Image-Guided Procedures, and Modeling, 2011)
One of the main challenges related to computer-assisted laparoscopic surgery is the accurate registration of pre-operative planning images with patient's anatomy. One popular approach for achieving this involves intraoperative 3D reconstruction of the target organ's surface with methods based on multiple view geometry. The latter, however, require robust and fast algorithms for establishing correspondences between multiple images of the same scene. Recently, the first endoscope based on Time-of-Flight (ToF) camera technique was introduced. It generates dense range images with high update rates by continuously measuring the run-time of intensity modulated light. While this approach yielded promising results in initial experiments, the endoscopic ToF camera has not yet been evaluated in the context of related work. The aim of this paper was therefore to compare its performance with different state-of-the-art surface reconstruction methods on identical objects. For this purpose, surface data from a set of porcine organs as well as organ phantoms was acquired with four different cameras: a novel Time-of-Flight (ToF) endoscope, a standard ToF camera, a stereoscope, and a High Definition Television (HDTV) endoscope. The resulting reconstructed partial organ surfaces were then compared to corresponding ground truth shapes extracted from computed tomography (CT) data using a set of local and global distance metrics. The evaluation suggests that the ToF technique has high potential as means for intraoperative endoscopic surface registration. © 2011 SPIE.

400Gbit/s DP-RZ-QPSK transmission over 1200Km SMF-28 employing digitalbackward propagation - Asif, Rameez; Lin, Chien-Yu; Usman, M.; Schmauß, Bernhard (SPIE 8284, 82840R, 2012)
lhft_intern.bib::Asif2012a

42-Gb/s Transmission Over Large-Core 1-mm PMMA Graded-Index Polymer Optical Fiber - Loquai, Sven; Kruglov, Roman; Winkler, Florian; Bunge, Christian-Alexander; Schmauß, Bernhard; Hartl, Engelbert; Ziemann, Olaf; Habel, Kai (IEEE Photonics Technology Letters, 2013)
The authors report on very high-speed data transmission over a large-core 1-mm polymethylmetacrylate (PMMA) polymer optical fiber (POF) using pulse amplitude modulation. A high-speed large-area 400 μm photoreceiver based on a gallium-arsenide metal-semiconductor-metal photodetector (PD) is used in order to reach the next major hurdle of 40 Gb/s over 1-mm PMMA POF. With this transmission setup record bit rates between 42 and 36 Gb/s were achieved over 1 to 10 m. © 1989-2012 IEE
UnivIS-Import:2015-03-09:Pub.2013.tech.IE.LEH.42gbst
Keywords: 40 Gb/s; optical fiber communication; polymer optical fiber (POF); pulse amplitude modulation (PAM)

43 Gb/s CP-QPSK Realtime Receiver Demonstrator based on FPGAs and Block Processing - Geyer, J.C.; Fludger, C.R.S.; Duthel, T.; Presslein, P.; Schulien, C.; Schmauß, Bernhard (ECOC 2009, Vienna, Austria, 20-24 September, 2009)
We present measurement results of an FPGA-based 43Gb/s Realtime Coherent Receiver Demonstrator. Due to limitations we use block-aggregation and process 1/32 of the input data stream. We show back-to-back performance and chromatic dispersion tolerance.
UnivIS-Import:2015-04-16:Pub.2009.tech.IE.LEH.43gbsc

468 Novel optical measurement technology for shock waves in lithotripsy - Granz, B; Nanke, R; Fehre, J; Pfister, T; Engelbrecht, Rainer; Schulz, R (European Urology Supplements, 2004)
lhft_intern.bib::engelbrecht04a

50 GHz Photoreceiver Modules for RZ and NRZ Modulation Format Comprising InP-OEICs - Bach, H.G.; Schlaak, W.; Mekonnen, G. G.; Steingrüber, R.; Seeger, A.; Passenberg, W.; Ebert, W.; Jacumeit, G.; Eckhardt, Th.; Ziegler, Rolf; Beling, A.; Schmauß, Bernhard; et al. (Conf. Proc. ECOC , September, 2001)
Monolithically integrated InP-based pinTWA photoreceiver optoelectronic integrated circuits (OEIC) with spot size converter and single-supply low power consumption were fabricated. Packaged photoreceivers operating up to the bandwidth of 50 GHz were demonstrated with 1.1 A/W conversion efficiency. Results showed that a higher transimpedance of 130 ohm was provided by cascode-type Rx OEICs with 1.7 A/W overall conversion efficiency showing 35 GHz bandwidth.
UnivIS-Import:2015-04-16:Pub.2001.tech.IE.LEH.50ghzp

600 GHz GaAs Schottky Diode Mixer in Split-block Technology - Schür, Jan; Biber, Stephan; Cojocari, O.; Schmidt, Lorenz-Peter; Hartnagel, H. (30th International Conference on Infrared and Millimeter Waves, 2005)
In this paper we present measurement results of a micro-machined split-block waveguide mixer for 600 GHz. The mixer implements a planar GaAs Schottky diode on a quartz substrate. Two different diode designs used for this mixer design are compared. The overall performance of the waveguide mixer is demonstrated by measurements of the mixer in a quasi-optical setup at 600 GHz. In this setup we are able to measure single sideband conversion losses of 9-14 dB at 600 GHz and voltage responsivities of 421-1690 mV/mW. © 2005 IEEE.
UnivIS-Import:2015-04-16:Pub.2005.tech.IE.LEH.600ghz_9
Keywords: 600 GHz; GaAs schottky diode; Heterodyne mixer; Micromachining; Split-block; THz-technology

600 GHz Heterodyne Mixer in Waveguide Technology using a GaAs Schottky Diode - Schür, Jan; Biber, Stephan; Cojocari, O.; Mottet, B.; Schmidt, Lorenz-Peter; Hartnagel, H. (16th International Symposium on Space Terahertz Technology ISSTT, 2005)
In this paper we will present first measurement results for a fixed tuned 600 GHz heterodyne mixer in split-block waveguide technology. The presented mixer design is based on a single planar GaAs Schottky diode which is flip-chip mounted on a quartz substrate. The split-block structure includes an octagonal horn antenna, a waveguide to microstrip transition and a coaxial IF output. In addition to the GaAs diode the quartz substrate includes the required low-pass filter structures which are also used for the DC bias of the diode. The mixer was manufactured by micromechanical milling in brass. With this mixer we were able to measure voltage responsivities up to 1690 V/W and single sideband conversion losses down to 9.4 dB at 600 GHz.
UnivIS-Import:2015-04-16:Pub.2005.tech.IE.LEH.600ghz
Keywords: heterodyne mixer; split-block; micromachining; 600 GHz; THz-technology; GaAs Schottky diode

600 GHz Waveguide Mixer fabricated by combined conventional and Silicon Micromachining - Schür, Jan; Biber, Stephan; Cojocari, O.; Sydlo, C.; Schmidt, Lorenz-Peter; Hartnagel, H. (Proceedings of the European Microwave Association, 2005)
UnivIS-Import:2015-04-16:Pub.2005.tech.IE.LEH.600ghz_1

64-GBd DP-Bipolar-8ASK Transmission over 120 km SSMF Employing a Monolithically Integrated Driver and MZM in 0.25-μm SiGe BiCMOS Technology - Mehrpoor, Gilda Raoof; Schmidt-Langhorst, Carsten; Wohlfeil, Benjamin; Elschner, Robert; Rafique, Danish; Emmerich, Robert; Dochhan, Annika; Lopez, Iria; Rito, Pedro; Petousi, Despoina; Kissinger, Dietmar; Zimmermann, Lars; et al. (2019 Optical Fiber Communications Conference and Exhibition, OFC 2019 - Proceedings, 2019)
We demonstrate 64-GBd signal generation up to bipolar-8-ASK utilizing a single MZM, monolithically integrated with segmented drivers in SiGe. Using polarization multiplexing, 300-Gb/s net data rate transmission over 120 km SSMF is shown.
CRIS-Team Scopus Importer:2019-05-21

6GEM Perspective on Joint Communication and Sensing - vom Bögel, Gerd; Sezgin, Aydin; Pohl, Nils; Vossiek, Martin; Weimer, Michael; Wessel, Jan; Wietfeld, Christian; Thill, Ruben; Braun, Tobias T.; Haferkamp, Markus; Sivadevuni, Srivardhan Sarma; Kögel, Tobias; et al. (WSA & SCC 2023; 26th International ITG Workshop on Smart Antennas and 13th Conference on Systems, Communications, and Coding, 2023)
Joint Communications and Sensing (JCS) requires innovative new technologies and solutions in both the HW and SW domains. The key factors for JCS are very high frequencies (GHz/THz) with large bandwidths, the agility of the 6G infrastructure spectrum, and the ability to process radio signals for multiple purposes. The Innovation potential in this area is huge, but technological challenges to be solved are also demanding. In the component and hardware area, frequency-agile RF components are subject of the development to support very high bandwidths with the lowest possible nonlinearity and power consumption. The common hardware and algorithmic challenge is to ensure coherent processing of signals, sensor fusion and in particular common waveform design, novel baseband solutions, JCS supporting packet structures and efficient edge-based processing. This article provides an overview of JCS from the perspective of the 6GEM projec
Keywords: terahertz communication; terahertz sensing; 5G and 6G technologies; JCS joint communication and sensing

76-81 GHz LTCC Antenna for an Automotive Miniature Radar Frontend - Sickinger, Frank; Weissbrodt, Ernst; Vossiek, Martin (14th European Radar Conference EuRAD, 2017)

76–81 GHz LTCC antenna for an automotive miniature radar frontend - Sickinger, Frank; Weissbrodt, Ernst; Vossiek, Martin (International Journal of Microwave and Wireless Technologies, 2017)
An automotive radar sensor for cocoon functions requires very small dimensions to offer a high flexibility of mounting positions. These mounting positions are the bumper corners, and in future, also the B-pillar and the rocker rail could become a mounting position. Therefore highly integrated radar sensors are required. Investigations for a miniature radar frontend have been done, based on RF360 low loss non shrinkage LTCC (low temperature cofired ceramic) substrate. For the automotive radar band (76-81 GHz), an antenna array has been simulated, manufactured and radiation pattern has been measure
lhft_intern.bib::Sickinger2018

8 QAM regeneration using a phase-sensitive amplifier with dual-conjugated pumps - Stiller, Birgit; Onishchukov, Georgy; Schmauß, Bernhard; Leuchs, Gerd (Optics InfoBase Conference Papers, 2013)
CRIS-Team Scopus Importer:2021-06-29

A 12Bit 8GS/s Randomly-Time-Interleaved SAR ADC with Adaptive Mismatch Correction - Linnhoff, Sebastian; Sippel, Erik; Buballa, Frowin; Reinhold, Michael; Vossiek, Martin; Gerfers, Friedel (International Symposium on Circuits and Systems (ISCAS), 2021)
This paper presents a wideband 12Bit 8GS/s time-interleaved successive approximation register (SAR) analog-to-digital converter (ADC), featuring a sub-2 radix architecture with an overrange of 10% and randomized sampling with mismatch correction in a 28nm CMOS technology. For this purpose, 18 500MHz SAR-ADCs plus an additional reference ADC are interleaved. This topology enables a randomization approach, reducing mismatch related interleaving spurs. Furthermore, the additional reference ADC operating in parallel to the main ADC enables adaptive digital calibration to correct for static and time-interleaved mismatch effects. A wideband front-end features two subsequent push-pull buffer stages to achieve a high track-and-hold (T/H) bandwidth and high sampling linearity, while improving kickback related settling limitations. After calibration, the ADC achieves a signal to noise and distortion ratio (SNDR) of 56.8dB and a spurious free dynamic range (SFDR) of 80dBc applying a single full scale sine wave tone close to the Nyquist frequency of 4GH

A 13.56 MHz Localization System Utilizing a Switched Injection Locked Transponder - Kirsch, Fabian; Vossiek, Martin; Schäfer, Tobias (IEEE Conference on Microwaves, Communications, Antennas and Electronic Systems (COMCAS) 2009, 2009)
In this paper a low-frequency local positioning system at 13.56 MHz is presented. The system is aiming at short range indoor localization problems, where a measurement through a crowd of people is required. Indoor navigation or information systems e.g. in museums, public buildings or fairs are possible applications. With a wavelength of approx. 22 m the system operates in the near field. Ranging is accomplished by measuring the phase shift between a transmitted CW base station signal and a response generated in the transponder with the use of the novel switched injection locked oscillator concept. First measurement results prove that the proposed concept allows for robust indoor ranging with an accuracy in the decimeter-rang
UnivIS-Import:2015-04-16:Pub.2009.tech.IE.LEH.a1356m
Keywords: Locked oscillators; Phase measurement; Transponders; Voltage controlled oscillators

A 180-GHz Super-Regenerative Oscillator with up to 58 dB Gain for Efficient Phase and Amplitude Recovery - Ghaleb, Hatem; Carlowitz, Christian; Fritsche, David; Starke, Paul; Protze, Florian; Carta, Corrado; Ellinger, Frank (IEEE Transactions on Microwave Theory and Techniques, 2020)
A 180-GHz super-regenerative oscillator capable of 58 dB gain and fast switching at a rate up to 10 GHz is implemented in a 130nm SiGe BiCMOS technology. It is the fastest reported super-regenerative circuit in terms of data-rate and the first one to be packaged in a standalone mm-wave waveguide module. The oscillator has a tuning range of 6.5%, an output power of 0.5 dBm, and occupies an area of 0.72 mm2. When operated with a periodic quench signal, the circuit requires a minimum input power of -58 dBm for a phase coherent output. The circuit has a dc power consumption of 8.8 mW. QPSK and 8-phase shift keying (PSK) modulations with data rates up to 3 Gbit/s are demonstrated. The circuit is also integrated into a waveguide module and used to recover a wireless stream of 16QAM data at 16 Gbit/s, which is the highest reported in a super-regenerative circuit to date.
CRIS-Team Scopus Importer:2020-06-19
Keywords: High-data-rate wireless communication; millimeter-wave integrated circuits; super-regenerative receivers

A 180-GHz Super-Regenerative Oscillator with up to 58 dB Gain for Efficient Phase Recovery - Ghaleb, Hatem; Carlowitz, Christian; Fritsche, David; Carta, Corrado; Ellinger, Frank (Digest of Papers - IEEE Radio Frequency Integrated Circuits Symposium, 2019)
This paper reports on the design of a 180-GHz super-regenerative oscillator in a 130nm SiGe BiCMOS technology. The oscillator has a tuning range of 6.5%, an output power of 0.5 dBm, and occupies an area of 0.72 mm2. When operated with a periodic quench signal, the circuit requires a minimum input power of-58 dBm for a phase coherent output, and can be switched at a rate up to 10 GHz. The circuit has a dc power consumption of 8.8 mW, and a maximum regenerative gain of 58 dB. QPSK and 8-PSK modulation up to 3 Gbit/s have been demonstrated at an energy efficiency of 2.9 pJ/bit. To the best knowledge of the authors, this work is the fastest reported phase-sampling super-regenerative oscillator to date.
CRIS-Team Scopus Importer:2019-09-24
Keywords: 200 GHz band; super-regenerative receiver

A 24 GHz SIMO radar tachymeter for precise transponder localization - Reustle, Christoph; Shmakov, Denys; Vossiek, Martin (IEEE MTT-S International Microwave Symposium, IMS 2015, 2015)
A tachymeter is a device that measures angle and distance to a cooperative target. Optical tachymeters are well established but they have shortcomings under harsh environmental conditions such as dense smoke, fog, dust, rain or snow. As a robust alternative, we developed an innovative radar tachymeter for precise and highly reliable operation. This device is a 24 GHz single-input and multiple-output radar system with a frequency-modulated continuous-wave secondary radar base station that measures the distance to a cooperative responder unit. The synthesizer is optimized for low phase noise and features highly linear frequency modulation for high-precision ranging. The radar system incorporates a sparse antenna array with 1 transmit and 8 receive channels. Angle and range are precisely estimated with a spatial optimal filter algorithm and a dedicated synchronization concept implemented on a compact embedded platform. The developed radar tachymeter has been tested in indoor scenarios as well as on a truck-mounted crane. The measurement campaigns showed that the root-mean square errors are as low as 0.1° and 1 cm, for angle and range respectively.
Keywords: Instrumentation and measurement; microwave sensors; position measurement; radar systems; transponders

A 24-GHz tank level gauging system with state-space frequency estimation and a novel adaptive model order selection algorithm - Pichler, Markus; Gulden, Peter; Vossiek, Martin; Stelzer, Andreas (IEEE MTT-S International Microwave Symposium, 2003)
For the evaluation of signals in frequency modulated continuous wave radar systems for object distance measurement tasks, highly sophisticated state-space frequency estimation algorithms pose an alternative to the traditionally used fast Fourier transformation. Current implementations of this approach suffer from instability problems when applied to real radar measurements. In this paper a method is presented to overcome the present stability problems by proposing a novel model order estimation procedure. With the use of practical measurements in a level gauging system an improvement of 2-3 over the resolution of the FFT-based methods is shown, and stability of the model order selection algorithm is proved.
UnivIS-Import:2015-04-16:Pub.2003.tech.IE.LEH.a24ghz

A 24-GHz Wireless Locating System for Human–Robot Interaction - Dobrev, Yassen; Pavlenko, Tatiana; Geiß, Johanna; Lipka, Melanie; Gulden, Peter; Vossiek, Martin (IEEE Transactions on Microwave Theory and Techniques, 2019)
Due to technological advances in various fields and the rising demand for automation, the popularity of service robots is expected to grow rapidly in the upcoming years. One of the core functions of such robots is their interaction with people. One type of interaction, which is studied in this paper, is when the robot leads or follows a person. This presupposes that the position of the person is known relative to the mobile robot. In this paper, we present a 24-GHz wireless locating system to enable this kind of human–robot interaction. The system consists of a radar node attached to the robot and an active portable wireless beacon that is carried by the person. Using a secondary radar approach to measure the distance and angle to the beacon, the 2-D position of the person relative to the mobile robot can be accurately determined by a single radar node on the robot. This is unfeasible with standard multilateration localization approaches. An extended Kalman filter is used to increase the accuracy and reliability of the positioning system. The measurements presented in this paper, performed in a scenario that is both challenging and realistic, demonstrate the effectiveness of the proposed approach.<br

A 2-Dimensional Realtime Millimeter-Wave Imaging System - Brand, Hans (1981)
lhft_intern.bib::thirty_years_LHFT_123

A 300 GHz quasioptical schottky frequency doubler - Shalaan, M; Bozzi, M; Weinzierl, Jochen; Beilenhoff, K; Conciauro, G; Brand, Hans; Hartnagel, H (International Journal of Infrared and Millimeter Waves, 1997)
A monolithically integrated frequency multiplier based on a planar antenna providing impedance matching has been realized and measured at 300 GHz. Each of the two circuits comprises a Schottky varactor, slot antenna, MIM-capacitor and microstrip bias feed. The theoretical design aspects, the technological approach and the RF performance are addresse
lhft_intern.bib::thirty_years_LHFT_413

A 3D-Modulated Delay Line-Based Chipless TDR UWB RFID System with High Suppression of Multiple Reflections - Pöpperl, Maximilian; Frank,; Mandel,; Jakoby,; Vossiek, Martin (46th European Microwave Conference, 2016)
lhft_intern.bib::Poepperl2016c

A 4th Harmonic Schottky Diode Mixer - Faciliated Access to THz Frequencies - Schür, Jan; Ruf, Marcel; Schmidt, Lorenz-Peter (IRMMW, Passadena / USA, September, 2008)
This paper will present first measurement results of a 4th harmonic Schottky diode mixer operating at 600 GHz. The mixer design compromises a rectangular waveguide based splitblock with an integrated quartz based mixer circuit. A low parasitic planar antiparallel Schottky diode pair is used to downconvert a 600 GHz signal by mixing with the 4th harmonic of the local oscillator. The local oscillator for the presented mixer consists of a 150 GHz PLL-locked frequency doubled Gunn oscillator providing a frequency and phase stabilized LO source for accurate measurements of the magnitude and phase of the RF signal. Simulations predict conversion losses well below 20 dB. Current evaluations of the mixer performance are proving the suitability for short range applications like material characterization and testing as well as for life sciences and medical applications.
UnivIS-Import:2015-04-16:Pub.2008.tech.IE.LEH.a4thha

A 75 - 110 GHz Seventh-Harmonic Balanced Diode Mixer in a Novel Circuit Configuration - Schneiderbanger, Dirk; Kneuer, C.; Sterns, Michael; Rehner, Robert; Martius, Siegfried; Schmidt, Lorenz-Peter (Proceedings of the 1st European Wireless Technology Conference, 2008)
We report on a novel balanced diode mixer circuit configuration. The mixer operates in a seventh harmonic mixing mode and is fed with the RF signal via a WR-10 waveguide. For a fixed IF of 750 MHz our mixer has very flat characteristics of conversion loss of about 19 dB ± 2.5 dB over the entire W-band (75-110 GHz). The mixer is straight forward to design and its fix-tuned hybrid integrated circuit is easy to manufacture. Only commercially available components are necessary. So our mixer design offers a smart and low-cost alternative solution for broadband receivers as well as for frequency extensions of spectrum analyzers and vector network analyzers. © 2008 EuMA.
UnivIS-Import:2015-04-16:Pub.2008.tech.IE.LEH.a75110

A 780-nW Frequency-Agile Fully Integrated Super-Regenerative Multi-Channel UHF Receiver for Continuous Spectral Monitoring - Eppel, Markus; Milosiu, Heinrich; Kögel, Tobias; Oehler, Frank (2019)
This paper proposes a frequency agile fully integrated super-regenerative receiver for spectral power estimation. A 180-nm implementation of the proposed receiver is presented with measurements.The receiver draws 26 mu A from a 1.8 Volt supply to scan 60 frequency points between 380 and 960 MHz every 1.8 ms, hence 780 nW per channel. The "resolution bandwidth" lies between 2 and 15 MHz, depending on the quench-signal. No external filter components are used. Filter quality factors greater than 400 are achieved, using an on-chip inductor. The best measured receiver sensitivity is -75 dBm.
Keywords: UHF; CMOS; integrated circuits; super regenerative receiver; spectrum analyzer; ultra-low power; UWB

Abbildung mit elektromagnetischen Mikrowellen, insbesondere von schnell bewegten Objekten - Brand, Hans (Frequenz, 1986)
lhft_intern.bib::thirty_years_LHFT_233

Abbildung mit elektromagnetischen Mikrowellen, insbesondere von schnell bewegten Objekten - Brand, Hans (Frequenz, 1986)
lhft_intern.bib::thirty_years_LHFT_219

Abbildung mit Mikrowellen - Grundbegriffe und Methoden - Brand, Hans (1984)
lhft_intern.bib::thirty_years_LHFT_178

A Bilateral 24 GHz Wireless Positioning System for 3D Real-Time Localization of People and Mobile Robots - Dobrev, Yassen; Vossiek, Martin; Shmakov, Denys (2015)

Ab Initio Calculations to Determine Tunneling Parameters for 4H-SiC Tunneling Field-Effect Transistor Simulations - Ley, Maximilian; Dick, Jan; Schulze, Jörg (2024 47th ICT and Electronics Convention, MIPRO 2024 - Proceedings, 2024)
TFETs are a type of transistor that switches band-to-band tunneling currents. Such devices are promising candidates for future integrated circuits, low-power electronics, and quantum applications. Device simulations of TFETs with the non-local tunneling model require material-specific parameters to correctly describe the band-to-band tunneling process. The material-specific parameters can be determined by atomistic simulations. These ab initio calculations allow fast and efficient determination of material-specific parameters without experimental input. This process is demonstrated for 4H-SiC, which is an indirect semiconductor with a large band gap to the direct conduction band valley. In 4H-SiC, phonon-assisted tunneling is the dominant tunneling process. For the validation of the simulated parameters, TCAD simulations of transfer characteristics are compared with those of measured devices.
CRIS-Team Scopus Importer:2024-07-19
Keywords: 4H-SiC; Ab initio calculations; atomistic simulations; band-to-band tunneling; quantum tunneling; TFET; Tunneling Field-effect Transistor; Zener tunneling

A Broadband Low Cost Millimeterwave Slotline Detector on Low Permittivity Substrate - Richter, Jürgen; Rehner, Robert; Schmidt, Lorenz-Peter (Proceedings of the European Microwave Conference , Paris, Oct., 2005)
A broadband low cost millimeterwave slotline detector circuit is proposed that can efficiently be realized on a low permittivity substrate (εr = 2.2) which is required for the integration of an antenna. The experimentally approved design achieved a voltage sensitivity of 1660 mV/mW at 77 GHz, with more than 1000 mV/mW between 62 and 85 GHz, a tangential signal sensitivity below -45 dBm and a 1-dB-compression point at -14.8 dBm. The sensitivity is about the same as for commercially available wave-guide detectors despite the unfavourably low substrate permittivity. The compact design and the low cost allow the integration of a larger number of such slotline detectors with antennas on a single substrate for a receiver array in a millimeterwave focal plane imaging system.
UnivIS-Import:2015-04-16:Pub.2005.tech.IE.LEH.abroad

A Broadband Low Noise Heterodyne Receiver at 2.5 THz - Huber, K.; Brand, Hans; Schmidt, Lorenz-Peter (Proceedings of the 8th International Conference on Terahertz Electronics, 2000)
UnivIS-Import:2015-04-16:Pub.2000.tech.IE.LEH.abroad

A broadband, low noise heterodyne receiver for stratospheric measurements at 2.5 THz - Huber, K; Engelbrecht, Rainer; Hocke, R; Raum, M; Brand, Hans; Martius, Siegfried; Schmidt, Lorenz-Peter (IEEE, 1999)
The LHFT is currently working on a broadband heterodyne receiver for stratospheric measurements at 2.5 THz. Many molecules and radicals such as OH, H/sub 2/O and O/sub 3/ which are involved in the stratospheric ozone chemistry exhibit characteristic emissions in this spectral range. In order to measure these spectra and extract concentration data of the single components, a platform operating at high altitudes is necessary to overcome atmospheric absorption due to water vapor. Research at the LHFT includes the construction of a stable and compact local oscillator (LO) as well as the development of the receiver front end. In the LO subsystem an RF excited grating tunable sealed off CO/sub 2/ laser with an apodized out-coupling element will be used as a pump source. The compact and rugged design is realized by a slab discharge geometry and a metal tube housing. Long term stable gas composition for sealed off operation is optimized during the design phase of the laser by making use of tunable diode laser absorption spectroscopy (TDLAS). A methanol ring-laser with an output power of up to 49 mW at 2522.8 GHz (pump power 20 W) has been developed and is available as a very powerful FIR source. The optimization of the front end concentrates upon broadband and low noise performance. A mixer with newly developed substrate-less Schottky diodes followed by a broadband, noise matched IF-amplifier allow for low noise operation over a frequency range from 6 to about 13 GHz, thus covering emission lines of at least the three species mentioned abov
lhft_intern.bib::thirty_years_LHFT_432

A Broadband, Low Noise Heterodyne Receiver for Stratospheric Measurements at 2.5 THz - Huber, K.; Engelbrecht, Rainer; Hocke, Ralf; Raum, Michael; Brand, Hans; Martius, Siegfried; Schmidt, Lorenz-Peter (Proceedings of IGARSS 99, 1999)
UnivIS-Import:2015-04-16:Pub.1999.tech.IE.LEH.abroad

A Broadband Transition between Dielectric and Planar Waveguides at Millimeterwave Frequencies - Richter, Jürgen; Yazici, Y; Ziegler, Christof; Schmidt, Lorenz-Peter (Proceedings of the 33rd European Microwave Conference, 2003)
A variety of transitions between rectangular dielectric waveguides and planar waveguides like microstrip or slotline have been designed to combine the advantages of dielectric waveguides at millimeterwaves with the excellent hybrid integration capabilities of planar circuits. FDTD field simulations have been applied to analyze and optimize the designed transitions with respect to low insertion and return losses as well as minimized mutual coupling between adjacent transitions. Experimental investigations between 60 and 90 GHz proved the promising results of the simulations with insertion losses between 0.5 and 1.5 dB over the full waveguide band (WR-12). The transitions can well be used for the integration of planar circuits into dielectric waveguides or rod antennas and the designed structures are scalable up to frequencies beyond 100 GHz. © 2003 EUMA.
UnivIS-Import:2015-04-16:Pub.2003.tech.IE.LEH.abroad

Absolute Phase-Based Distance Measurement for Industrial Monitoring Systems - Schicht, A.; Huber, K.; Ziroff, A.; Willsch, M.; Schmidt, Lorenz-Peter (IEEE Sensors Journal, 2009)
In this paper, principal considerations for a high accuracy millimeter wave (mmw) radar distance measurement system applicable to be used in harsh industrial environments are presented. The system is based on continuous wave (CW) measurement of the reflection coefficient and interpretation of the signal phase. The ambiguity of the phase is overcome by means of a multiple frequency technique. For absolute distance determination, an online calibration procedure is applied. The applicability of the system is underlined by a laboratory demonstrator measurement. © 2009 IEEE.
UnivIS-Import:2015-03-09:Pub.2009.tech.IE.LEH.absolu
Keywords: Calibration; Distance measurement; Millimeter wave radar; Multiple frequency continuous wave (CW) radar; Phase measurement

Absolute spectral backscatter measurements of large-core multimode PMMA polymer optical fibers - Dengler, Simon A.; Engelbrecht, Rainer; Schmauß, Bernhard (Optics Express, 2021)
To our knowledge, we are the first to measure the absolute value of the backscattering coefficient of a standard 1 mm core-diameter, multimode (MM) step-index (SI) polymethylmethacrylate (PMMA) polymer optical fiber (POF) for the spectral range of 450 nm to 700 nm. Our optical time domain reflectometer (OTDR) setup consists of a femtosecond supercontinuum laser with an acousto-optical filter as a tunable light source with short pulses and a time-correlated single-photon counting system as a receiver with a high dynamic range. The backscattering coefficient is calculated from the ratio between the energy within the fiber end reflex and the distributed backscattering level. We also measured the spectral attenuation with our OTDR setup and compared it with a standardized measurement method. At the attenuation minima within the measured spectral range the backscattering level of a 1 ns pulse is about -46 dB at 520 nm, -48 dB at 570 nm, and -51 dB at 650 nm. We were also able to show by the observed wavelength dependence that Rayleigh scattering causes a majority of the scattering.
CRIS-Team Scopus Importer:2021-10-22

Absorption line strengths of ^15NH_3 in the NIR spectral region and potential for isotopic ratio measurements of ^15NH_3 and ^14NH_3 - Lins, Bastian; Engelbrecht, Rainer; Schmauß, Bernhard; et al. (FLAIR 2009 - Field Laser Applications in Industry and Research, 2009)
UnivIS-Import:2015-04-16:Pub.2009.tech.IE.LEH.absorp

Absorption line strengths of 15 NH3 in the near infrared spectral region - Lins, Bastian; Pflaum, Felix; Engelbrecht, Rainer; Schmauß, Bernhard (Applied Physics B-Lasers and Optics, 2011)
UnivIS-Import:2015-03-09:Pub.2011.tech.IE.LEH.absorp

Accuracy evaluation of asymptotic methods for the electromagnetic simulation of personnel security screening - Schnattinger, Georg; Schüßler, Christian; Root, Konstantin; Vossiek, Martin (Radar Sensor Technology XXVIII, 2024)
Cutting-edge personnel security screening relies on microwave imaging, where addressing future security demands entails integrating digital twins into development and testing processes. To create a realistic digital twin for microwave imaging systems, accurate replication of microwave images obtained from scanning real individuals is crucial, achieved through electromagnetic simulation. Employing fast simulation methods reduces the computational load to a viable level, yet it introduces some computational inaccuracies due to underlying approximations. The extent to which these inaccuracies affect microwave images is often unclear, while digital twins are already being used. To thoroughly assess this unknown influence, the simulation results obtained with physical optics (PO) and geometrical optics (GO) are compared with an integral equation (IE) solution approach using two scenarios of a walk-through personnel security screening in the frequency band below 10.6 GHz. Remarkably, while radar images are highly similar, raw signals exhibit significant deviations. Thus, for radar image simulation, PO and GO appear sufficiently accurate, offering attractive runtimes below two minutes per simulation. Conversely, the IE method proves impractical in many situations, as a single image necessitates over three weeks of computations.<br

Achieving Efficient and Realistic Full-Radar Simulations and Automatic Data Annotation by Exploiting Ray Meta Data from a Radar Ray Tracing Simulator - Schüßler, Christian; Hoffmann, Marcel; Wirth, Vanessa; Eskofier, Björn; Weyrich, Tim; Stamminger, Marc; Vossiek, Martin (IEEE Xplore, 2023)
In this work, a novel radar simulation concept for efficiently simulating realistic radar data for range, Doppler, and arbitrary antenna positions is introduced. With the concept, the simulated radar signal can also be automatically annotated by splitting it into multiple parts. Annotations that are almost perfect - including the annotation of exotic effects, such as multi-path - can be produced with this approach. Signal parts originating from different parts of an object can be labelled with it as well. To this end, the computation process used in a Monte Carlo shooting and bouncing rays (SBR) simulator is adapted. By considering the hits of each simulated ray, various meta data can be stored, such as hit position, mesh pointer, object IDs, and many more. This collected meta data can then be utilized to predict path-length changes caused by object motion to obtain Doppler information or to apply specific ray filter rules to obtain radar signals that only fulfil specific conditions, such as multiple bounces, or signals that contain specific object IDs. Using this approach, perfect, and otherwise almost impossible, annotation schemes can be realize
Keywords: Automotive Radar; Radar Simulation; Data Annotation

A Compact 77 GHz IQ-Modulated Transponder for High Gain and High Dynamic Range Radar Target Simulation - Birkenhauer, Christoph; Körner, Georg; Stief, Patrick; Hofmann, Andreas; Alami El Dine, Mohamad; Carlowitz, Christian; Vossiek, Martin (IEEE MTT-S International Microwave Symposium Digest, 2023)
This paper explores the concept and design of a transponder for radar target simulators (RTSes) within the 77GHz automotive radar band. The modulator is based on PIN diode attenuators arranged in an IQ configuration with additional amplification. Novel design strategies and components were implemented and evaluated during the design process. The layout is based on circular waveguide elements and the RF phase can be tuned even after fabrication. In addition, the signal can be varied for modulation by 28dB using an additional tuning range of 24dB for the gain setting. The usable RF bandwidth ranges over 10GHz centered at 80GHz, whereas the modulation bandwidth is set to 10MHz via the implemented filter characteristic of the driving circuit. This covers the relevant range of automotive radars operating at 77GHz.
CRIS-Team Scopus Importer:2023-09-01
Keywords: current source; phase shifter; PIN diode modulator; radar target simulation; radar transponder; SIW; substrate integrated waveguide

A Compact Fiber-Optic CO and CO_2 Spectrometer: Analysis of Noise, Sensitivity and Lineshapes - Engelbrecht, Rainer; Kuntz, F.; Euring, J.; Krause, M.; Neumann, S.; Schmidt, Lorenz-Peter (4th Int. Conference on Tunable Diode Laser Spectroscopy TDLS 2003, Zermatt, CH, 14.- 18.Juli, 2003)
UnivIS-Import:2015-04-16:Pub.2003.tech.IE.LEH.acompa

A compact NIR fiber-optic diode laser spectrometer for CO and CO: analysis of observed 2f wavelength modulation spectroscopy line shapes - Engelbrecht, Rainer (Spectrochimica Acta Part A-Molecular and Biomolecular Spectroscopy, 2004)
A compact fiber-optic diode laser spectrometer for the measurement of CO and CO2 gas concentrations in the near infrared around 1580 nm is described. By use of a balanced receiver to suppress diode laser intensity noise a sensitivity of 6.4 × 107 at 1 Hz system bandwidth was achieved. At a reduced pressure of 80 hPa this equals to a detection limit of 5.1 ppm CO and 9.1 ppm CO2 with 1 m absorption path length. The observed line shapes of the 2f wavelength modulation spectroscopy (WMS) scheme are analyzed theoretically and experimentally. Accurate measurements of magnitude and phase of the diode laser frequency and intensity modulation responses were found critically for modeling the observed line shapes. In situ measurements of gas dissociation processes inside of a medium-power carbon dioxide laser are presented as an application example. © 2004 Elsevier B.V. All rights reserved.
UnivIS-Import:2015-03-09:Pub.2004.tech.IE.LEH.acompa
Keywords: Carbon dioxide; Carbon monoxide; Line shapes; Near infrared; Noise analysis; Optical fiber; Tunable diode laser; Wavelength modulation spectroscopy

A Compact System for Systematic Noise Measurement of Schottky Diodes for THz Applications - Biber, Stephan; Koca, Oe; Huber, K.; Rehm, Guenther; Schmidt, Lorenz-Peter (Conference Proceedings of the European Microwave Week, 2002)
As Schottky diodes still remain the most frequently used devices in THz mixers, precise evaluation of their DC and noise performance is essential for the improvement of mixers in the sub-millimeter wave regime. We present first results from a measurement system which is able to measure the DC characteristics and the noise for Schottky diodes as a function of frequency and bias current. The automated system is capable of contacting many diodes consecutively. © 2002 IEEE.
UnivIS-Import:2015-04-16:Pub.2002.tech.IE.LEH.acompa

A Comprehensive Analysis of Quasiplanar Waveguides for Millimeter-Wave Application - Schmidt, Lorenz-Peter (European Microwave Conference, 1981)
Quasiplanar waveguides are analyzed which consist of a thin, partially metallized dielectric substrate inserted in the E-plane of a rectangular waveguide. Several slots or strips in symmetric or non-symmetric positions are allowed on each substrate surface. The analysis is based on a simplified formulation of the spectral domain immittance matrix followed by a Galerkin's method. The analysis has been extended to include the computation of higher order propagating and evanescent modes as well as the characteristic impedances of the dominant modes. Numerical results are presented for various configurations with strips or slots on one or both air-dielectric interfaces illustrating the flexibility of the applied metho
lhft_intern.bib::Schmidt9

A Comprehensive Experimental Characterization of a Far Infrared Ring Laser - Biber, Stephan; Schulz, Roland; Beyer, Matthias; Schmidt, Lorenz-Peter (International Journal of Infrared and Millimeter Waves, 2003)
We examine the possibilities to use a CO2-pumped FIR-ring laser system, which was optimized for operation at 2.5THz, for the generation of other FIR-lines using inethanol as laser-active medium. Five laser lines between 1.7 and 4.8THz were detected and characterized with respect to the maximum achievable output power, beam quality and optimum methanol pressure. Mode patterns for most of the lines were recorded in order to allow easy adjustment of the system and line-identification.
UnivIS-Import:2015-03-09:Pub.2003.tech.IE.LEH.acompr
Keywords: Beam Analysis; Far-Infrared-Laser-Design; Mode Analysis; THz-Sources

A Computationally Efficient Reconstruction Approach for Imaging Layered Dielectrics With Sparse MIMO Arrays - Ullmann, Ingrid; Vossiek, Martin (IEEE Journal of Microwaves, 2021)
This contribution presents a novel, computationally efficient approach to radar imaging of layered dielectrics with sparse MIMO arrays. Our concept does not impose any constraints on the array topology and at the same time promises to be more efficient than the state-of-the-art backprojection algorithm because it can make use of k-space reconstruction schemes. Experimental results with a sparse, non-equidistantly sampled array are provided. These demonstrate the feasibility of the approach and that the computational burden could be reduced by several orders of magnitude in a given practical example related to radar based non-destructive testin

A Concept for Infrastructure-Independent Localization and Augmented Reality Visualization of RFID Tags - Kunkel, Sebastian; Bieber, Robert; Huang, Ming-Shih; Vossiek, Martin (IEEE MTT-S International Microwave Workshop on Wireless Sensing, Local Positioning, and RFID, 2009)
In this paper we present a multi sensor concept for localization and augmented-reality visualization of backscatter RFID tags. The sensor data of a camera and a RFID FMCW reader system are combined based on a synthetic aperture radar principle. The system enables the localization of tagged goods without the use of any installed infrastructure. We integrate a FMCW RFID reader and a camera system into a handheld device. While the handheld device is moved around, radar measurements as well as images of the surrounding area are taken at a number of locations. Thus, a synthetic aperture is generated and the position of the tags is calculated based on a SAR localization algorithm. Based on the imagery of the camera the user receives an augmented visual impression of where to And the RFID transponders. ©2009 IEEE.
UnivIS-Import:2015-04-16:Pub.2009.tech.IE.LEH.aconce
Keywords: Augmented reality; Localization; RFID; Synthetic aperture radar; Transponders

A Concept for Lightweight UAV-Based Radar Remote Sensing Assisted by Wireless Local Positioning - Schütz, Martin; Vossiek, Martin (Mine Detection Symposium 2017, 2017)
lhft_intern.bib::schuetz17b

A Contiguos Ultra-Broadband Planar Diplexer from DC-67 GHz - Rehner, Robert; Reck, Christoph; Schneiderbanger, Dirk; Sterns, Michael; Martius, Siegfried; Schmidt, Lorenz-Peter (International Workshop on Microwave Filters, CNES, Toulouse, France, 16-18 October, 2006)
UnivIS-Import:2015-04-16:Pub.2006.tech.IE.LEH.aconti

A Convolutional Neural Network Approach to Parking Monitoring in Urban Radar Sensing - Martinez Garcia, Javier; Zoeke, Dominik; Vossiek, Martin (European Microwave Week / EuRAD, 2017)

A Cooperative Radar System With Active Reference Target Synchronization for Kinematic Target Analysis - Edstaller, Stefan; Mueller, Dominik (IEEE Transactions on Microwave Theory and Techniques, 2021)
This article presents a short-range cooperative radar system in the 77-GHz band for the estimation of kinematic parameters, such as position, velocity, and acceleration of a target. The proposed system uses two FMCW radar sensors that are operated incoherently and only depend on a common trigger for coarse synchronization. The resulting frequency offset and phase offset in the beat spectrum of the radar sensors are eliminated through calibration with a known active reference target. For easy detection of the reference target in the beat spectrum, a novel interchirp modulation method is proposed. The sampled data of a single receive channel of only one of the sensors of the system allow for a complete estimation of the kinematic target parameters. The theoretical analysis of incoherent FMCW radar systems is carried out, and the constraints and signal processing algorithms are derived from the results. The theory and operating principle of the proposed system are verified through measurements in an anechoic chamber. The accuracies for the position, velocity, and direction of movement (DoM) estimation are better than 10 mm, 0.03 m/s, and 1.4°, respectively.
CRIS-Team Scopus Importer:2021-06-11
Keywords: Bistatic radar; cooperative systems; millimeter-wave radar; position measurement; radar applications; radar detection; radar signal processing; radar theory; radar tracking; velocity measurement.

A Coplanar Waveguide Resonator Based In-Line Material Characterization Sensor for Bulk and Metallized Dielectrics - Talai, Armin; Gold, Gerald; Frank, Martin; Mann, Sebastian; Weigel, Robert; Kölpin, Alexander (Frequenz, 2016)
Microwave Materials such as Rogers RO3003 are subject to process-related fluctuations in terms of the relative permittivity and dielectric loss. The behavior of high frequency circuits like patch-antenna arrays and their distribution networks is dependent on the effective wavelength. Therefore, fluctuations of the complex permittivity will influence the resonance frequency and beam direction of the antennas. This paper presents a grounded coplanar waveguide based sensor, which can measure the complex permittivity at 77 GHz, as well as at other resonance frequencies, by applying it on top of the manufactured depaneling. The relative permittivity of the material under test (MUT) is a function of the resonance frequency shift and the dielectric loss of the MUT can be determined by transmission amplitude variations at the resonances. In addition, the sensor is robust against floating ground metallizations on inner printed circuit board layers, which are typically distributed over the entire surface below antennas. Furthermore, the impact from conductor surface roughness on the measured permittivity values is determined using the Gradient Mode
lhft_intern.bib::talai2016a

A Cost-Efficient Hybrid UHF RFID and Odometry-Based Mobile Robot Self-Localization Technique With Centimeter Precision - Kammel, Christoph; Kögel, Tobias; Gareis, Matthias; Vossiek, Martin (IEEE Journal of Radio Frequency Identification, 2022)
This paper presents an indoor localization approach that determines the absolute position of a mobile robot platform with centimeter precision by fusing RFID localization results based on cost-effective, standard passive UHF RFID technology with the robot’s odometry data. The mobile robot platform is equipped with a multistatic UHF RFID interrogation system, and several RFID tags are arbitrarily placed within the localization environment, serving as landmarks. The RFID localization concept is based on phase evaluations. To overcome the problem of ambiguous position estimations due to the 2π-phase ambiguity of the RFID signal phase and mitigate the linearization problem of the nonlinear system, a novel algorithm based on an iterative multihypothesis Kalman filter is introduced. A realistic simulation setup is developed to validate the proposed filter algorithm. By tracking a UHF RFID-equipped mobile robot platform in a real-world office environment, the proposed approach is also practically tested in terms of real-time capability, everyday suitability, and multipath resistance. Given that centimeter precision is only achieved in environments with weak multipath propagation, the RFID localization results are fused with odometry data provided by the robot. This effectively compensates for offset and drift in the odometry sensor, achieving a root-mean-square localization error of 2.7 cm.<br
Keywords: autonomous robot; global localization; indoor positioning; Industry 4.0; Internet of Things; iterative unscented Kalman filter; MIMO; multihypothesis Kalman filtering; phase-based localization; radio frequency identification; RFID robot; self-localization; synthetic aperture; UHF RFID

Acquisition of Power Deposition Patterns Characterizing Superficial Microwave Applicators for Hyperthermia - Erb, J; Engelbrecht, Rainer; Schaller, G; Seegenschmiedt, H; Sauer, R (1994)
lhft_intern.bib::thirty_years_LHFT_346

Acquisition of Power Deposition Patterns Characterizing Superficial Microwave Applicators for Hyperthermia - Erb, J.; Engelbrecht, Rainer; Schaller, Gerhard; Seegenschmiedt, Heinrich; Sauer, R. (Joint Meeting of Europ. Soc. for Radiation Biology (ESRB) and Hyperthermia Oncology (ESHO), 1994)
UnivIS-Import:2015-04-16:Pub.1994.tech.IE.LEH.acquis

A custom lightweight UAV for radar remote sensing: Concept design, properties and possible applications - Schütz, Martin; Oesterlein, Martin; Birkenhauer, Christoph; Vossiek, Martin (2017 IEEE MTT-S International Conference on Microwaves for Intelligent Mobility (ICMIM 2017), 2017)
In this paper, we introduce a novel, tailor-made UAV-based sensor platform for radar remote sensing. It is controlled by a redundantly implemented, customized flight control and equipped with a comprehensive embedded system for radar baseband processing. Both systems are synchronized with a common, low-phase noise and temperature-stable reference clock, which allows coherent acquisition and continuous recording of sensor data. A commercial differential GPS system is used for positioning. The platform potentially allows interferometric remote sensing with synthetic apertures. In a first case study, it is equipped with a bistatic 24GHz MIMO radar system to create a side-looking-airborne-radar, allowing full interferometric SAR processing. As a proof-of-concept, a radar altimeter measurement is presented, which replaces and outperforms common altitude estimators, such as barometric or ultra sonic sensor

Adaptions for Automotive Radar Based Occupancy Gridmaps - Prophet, Robert; Stark, Henriette; Hoffmann, Marcel; Sturm, Christian; Vossiek, Martin (IEEE MTT-S International Conference on Microwaves for Intelligent Mobility (ICMIM 2018), 2018)
Environment models are necessary for autonomous driving. The distinction between drivable and non-drivable underground is elementary. This paper presents adaptions for radar based occupancy gridmaps, which are a common representation of the environment. In contrast to standard occupancy gridmaps or in general standard inverse radar sensor models, our approach works with velocity dependent parameters and extends free space calculations. Consequently, the map quality varies less and the information content of the ego vehicle's immediate vicinity is higher. Experiments with ground truth data show that the proposed algorithm produces accurate environment models in urban scene
lhft_intern.bib::Prophet18

Adaptive digital back-propagation for optical communication systems - Napoli, A.; Kuschnerov, M.; Lin, Chien-Yu; Spinnler, B.; Bohn, M.; Rafique, D.; Sleiffer, V.; Schmauß, Bernhard (Optical Fiber Communication Conference, 2014)
We propose an adaptive digital back-propagation method (A-DBP) to self-determine unknown fiber nonlinear coefficient gamma. Performance is experimentally verified with 10×224-Gb/s POLMUX-16QAM over 656km. Optimal DBP performance, without knowledge of gamma, is obtained by A-DBP.
lhft_intern.bib::Napoli2014

Additive Fertigung in der Hochfrequenztechnik – Potenziale und Herausforderungen - Lomakin, Konstantin; Sippel, Mark; Gold, Gerald; Rochholz, P; Helmreich, Klaus; Ankenbrand, Markus; Gräf, Daniel; Franke, Jörg (PLUS - Produktion von Leiterplatten und Systemen, 2017)

Additively Manufactured Amplitude Tapered Slotted Waveguide Array Antenna with Horn Aperture for 77GHz - Lomakin, Konstantin; Alhasson, Saif; Gold, Gerald (IEEE Access, 2022)
In this work, a combined frontend of horn and slotted waveguide array antenna serving as feeding subsystem is presented. This setup allows to implement an amplitude taper in one plane while using the horn aperture to shape the far field radiation characteristics in the perpendicular plane independently and tailored to the individual demand of the application. Moreover, the feeding system is implemented as a loop resulting in a standing wave distribution for a wide frequency range in order to increase the antenna bandwidth. Two specimens with different horn apertures are additively manufactured in slotted waveguide technology from UV curable photopolymer resin using a digital light processing 3D printer and subsequently metal coated by electroless silver plating. A relatively large bandwidth of B-10dB=7.2 GHz and a B-15dB of 4.9 GHz is achieved in measurements indicating a relative bandwidth of 9% and 6% respectively. Antenna Gain is characterized as 17.5 and 20.17 dBi in measurements while maintaining a sidelobe level of 20-22.5 dB at 77 GHz and exhibiting a radiation efficiency of 78.9 and 79.4%. The proposed antenna architecture provides a flexible approach for beam shaping in applications where azimuth and elevation planes exhibit different or contrary requirements, e.g. broad vs. narrow field of view - especially suitable for automotive MIMO-radar sensor

Additively manufactured antennas based on slotted ridged waveguides for 77 GHz MIMO radar applications - Kleinlein, Micha; Lomakin, Konstantin; Rösner, Felix; Hofmann, Andreas; Sippel, Mark; Gold, Gerald (2023 IEEE Conference on Antenna Measurements and Applications (CAMA), 2023)
In this work an additively manufactured waveguide antenna array for automotive radar applications is presented. The antenna is based on a slotted single ridged waveguide design with four radiating elements in the elevation plane. This allows for a λ 0 /2 spacing at 76 to 77 GHz, which is desirable to minimise azimutal angular ambiguities in automotive radar applications. The influence of adjacent surfaces close to the radiating slots in the azimutal field of view (FoV) is evaluated based on simulations and measured prototypes, especially demonstrating its role when extending the FoV towards ±70°. Furthermore, the impact on mutual coupling with neighboring antenna elements and the interaction of several channels with the arrays’ cover are evaluated based on a 4x4 channel array prototype, which is also manufactured and measured. The entire antenna arrays are manufactured monolithically with a photopolymer based 3D-printing process and subsequently electroplated in cooperation with Golden Devices Gmb
Keywords: Antenna measurements; Slot antennas; Surface waves; Three-dimensional printing; Radar antennas; Loss measurement; Radar applications

Additively Manufactured Broadwall Waveguide Couplers for V-Band Applications - Hofmann, Andreas; Lomakin, Konstantin; Sippel, Mark; Gold, Gerald (German Microwave Conference, 2022)

Additively Manufactured Circular Polarized V-Band Phased Antenna Array - Shi, Jing; Pietschmann, Simon; Bachbauer, Felix; Akula, V.; Maune, H.; Gold, Gerald (2025 IEEE Wireless and Microwave Technology Conference, WAMICON 2025, 2025)
Due to the demand for inter-satellite V-band communication between CubeSats, a circular polarized phased shifted 1 × 4 horn antenna array was designed. The whole structure includes two parts, the 1 × 4 linear polarized horn antenna array, manufactured with Selective Laser Sintering-Fine Details Resolution (SLS-FDR) technology, and a circular polarizer that was manufactured with Projection Micro Stereolithography (P μ SLA). With the help of waveguides of different length, the antenna array could be measured at a phase difference of 120°. They serve as placeholders and are included to be replaced by liquid crystal (LC) phase shifters in later application. The beam steering angle of the 1 × 4 antenna array reached 10° and 11°. The measured axial ratios (AR) at the two steering angles are 2.84 dB and 3.61 dB.
CRIS-Team Scopus Importer:2025-06-20
Keywords: Additive Manufacturing; Circular Polarization; CubeSats; LC Phased Antenna Array; P muSLA; SLS-FDR; V-band

Additively Manufactured Dielectric Waveguides for Advanced Concepts for Millimeter-Wave Interconnects - Distler, Felix; Sippel, Mark; Schür, Jan; Gold, Gerald; Helmreich, Klaus; Vossiek, Martin (IEEE Transactions on Microwave Theory and Techniques, 2019)
Technology mega trends, such as autonomous driving, multiple-input multiple-output (MIMO), or multi-gigabit communication, drastically increase the demand for ultra-broadband millimeter-wave (mmW) transmission line technologies. A broadband and robust signal and data transmission between components and modules at low cost is a mandatory requirement to ensure high-performance functionality of advanced communication and radar systems. Dielectric waveguides (DWGs) are a highly suitable technology to meet these requirements due to their outstanding transmission capabilities for mmW signals coupled with their high flexibility, low weight, and low cost. Additive manufacturing (AM) processes based on dielectric materials open up new perspectives for fully automated wiring of mmW modules and systems, and they enable cost-efficient application-specific solutions. In this article, we propose novel printed DWG designs with optimized transmission performance. Measurement results of different DWG designs demonstrate the excellent functionality of the proposed transmission line and interconnection concepts. These results and the shown resiliency and practicality of the presented approaches illustrate attractive opportunities for new interconnect technologies based on new manufacturing processe

Additively Manufactured Endfire Bifilar Helix Antenna for E-Band - Panusch, David; Shi, Jing; Lomakin, Konstantin; Gold, Gerald (EuCAP 2023 - 17th European Conference on Antennas and Propagation, 2023)
In this work, an additively manufactured endfire bifilar helix antenna with a center frequency of fc = 66 GHz employing a novel transition from bifilar helix to E-band waveguide is presented. This novel transition enables a higher bandwidth of the antenna and also tuning of the antenna matching. Mea- surements suggest a -20 dB-bandwidth of B20dB ≈ 5.2 GHz and -15 dB-bandwidth of B15dB = 16 GHz respectively. An axial ratio below AR<3.15dB is achieved over the entire E-Band and even AR < 2 dB within B20dB in main lobe direction. The realized linear polarization gain ranges at Glp 11 dBi with a circular polarization gain of Gcp 12 to 13dBi was measured. Hence, measurements suggest general feasibility of the proposed bifilar helix antenna for mmWave applications due to the small form factor of the antenna and the circular polarization. Those applications in future could be satellite systems or future 6G infrastructures.
Keywords: helix antenna; E-Band; additive manufacturing; SLA; WR12; mmWave; 6G

Additively Manufactured Helix Antenna for X-Band Applications - Panusch, David; Hubert, Florian; Bachbauer, Felix; Lomakin, Konstantin; Gold, Gerald (EuCAP 2022 - 16th European Conference on Antennas and Propagation, 2022)
This paper presents an additively manufactured helix antenna for X-Band applications with a center frequency of 10GHz. A comparison between stereolithography and selective laser sintering processes is made. The proposed antenna concept includes a transition from the helix coil to an X-band waveguide, which allows for matching of the antenna to the waveguide. In our measurements, the proposed antennas featured a -10dB-bandwidth of 2.8GHz and a -20dB-bandwidth of 0.28GHz respectively. The suggested manufacturing and design process is, therefore, a major step towards enabling complex antenna geometries.
Keywords: Helix antenna; X-Band; additive manufacturing; SLA; SLS; WR90

Additively Manufactured Leaky Wave Antenna in Dielectric Image Line Technology - Bader, Tobias; Gold, Gerald (2024 54th European Microwave Conference, EuMC 2024, 2024)
In this article a leaky wave antenna for 75 to 110 GHz is presented. Both, the dielectric transmission line as the basis and the conductive radiating elements on top of it were produced with an additive manufacturing process. The dielectric was generated by extruding a very low-loss thermoplastic material, whereas the antenna elements were made of a nano-particle silver ink using a piezo-driven inkjet print head. The final antenna consists of a 30 mm dielectric strip with 6 dipoles resulting in a measured gain of 12.8dBi, a measured side-lobe level of 12.2dB and a half power beam width of 9.1° at 90 GHz. It is to form the basis for a later steerable array antenna in the image line circuitry for the THz-region.
CRIS-Team Scopus Importer:2024-12-13
Keywords: additive manufacturing; dielectric image line; leaky wave antenna

Additively Manufactured Phase-Shifted Antenna Array Model in V-Band - Shi, Jing; Akula, V.; Bachbauer, Felix; Pietschmann, Simon; Maune, H.; Gold, Gerald (2024 54th European Microwave Conference, EuMC 2024, 2024)
A proposed design for a compact liquid crystal (LC) V-Band phased antenna array for inter-satellite links between CubeSats was unveiled, which includes an antenna array, feeding network, and LC phase shifter. In this work, a 4x4 horn antenna array with a corporate feeding network and length varied waveguides as an alternative to LC phase shifter were printed, which was supported with fine detail resolution (FDR) additively manufacturing technology. The phased antenna array was tested at 62.5 GHz with beam steering at 6°, 12°, and 18°, and its gain ranged from 23.79 dB to 18.65 dB in the azimuth plane and from 23.36 dB to 16.65 dB in the elevation plane.
CRIS-Team Scopus Importer:2024-12-13
Keywords: CubeSat; FDR additively manufacturing; feeding network; inter-satellite links; LC phase shifter; phased antenna array; V-Band

Additively Manufactured Six-Port for mmWave Applications - Klein, Laura; Lomakin, Konstantin; Sippel, Mark; Helmreich, Klaus; Gold, Gerald (2020 50th European Microwave Conference (EuMC), 2021)
This work presents, for the first time, an additively manufactured six-port for applications in the mm-Wave frequency range. The formative body of the structure is generated by a low-cost SLA photopolymer printing system. Conductive coating is subsequently applied by an electroless silver plating process that is in turn improved by the slotted waveguide approach. Despite the complex geometry, strict dimensional requirements for correct phase relations and large system size due to measurement feed paths, the obtained measurement results indicate promising future prospects towards practical application

Additively Manufactured Slotted Waveguides for THz Applications - Hofmann, Andreas; Lomakin, Konstantin; Sippel, Mark; Gold, Gerald (IEEE/MTT-S International Microwave Symposium (IMS), 2022)

Additively Manufactured Wavemode Transition for Broadband E-Band Applications - Lomakin, Konstantin; Engel, Lukas; Fleischmann, Johannes; Gold, Gerald (2021 IEEE/MTT-S International Microwave Symposium (IMS), 2021)
This work proposes an additively manufactured full E-band wavemode transition from WR12 waveguide to differential microstrip line. The specimens are fabricated using an industrial grade digital light processing (DLP) printing system with a subsequent electroless silver plating incorporating the slotted waveguide approach. Measurements at a back-to-back setup yield a matching of |S11| < −15 dB over the entire E-band and an overall attenuation of nearly < 3 dB including two transitions and a 30 mm differential microstrip transmission line (MSL) in between. Hence, an insertion loss of far less than 1.5 dB is achieved for each transition, indicating suitability for mm-Wave applications.<br

Additively Manufactured WR15 Waveguide to Microstrip Transition for Broadband V-Band Applications - Hofmann, Andreas; Klein, Laura; Lomakin, Konstantin; Sippel, Mark; Gold, Gerald (European Microwave Conference (EuMC), 2022)

Additive Manufactured Waveguide for E-Band Using Ceramic Materials - Hubert, Florian; Bader, Tobias; Wahl, Larissa; Hofmann, Andreas; Lomakin, Konstantin; Sippel, Mark; Travitzky, Nahum; Gold, Gerald (Applied Sciences, 2021)
Ceramic materials are chemical- and temperature-resistant and, therefore, enable novel application fields ranging from automotive to aerospace. With this in mind, this contribution focuses on developing an additive manufacturing approach for 3D-printed waveguides made of ceramic materials. In particular, a special design approach for ceramic waveguides, which introduces non-radiating slots into the waveguides sidewalls, and a customized metallization process, are presented. The developed process allows for using conventional stereolithographic desktop-grade 3D-printers. The proposed approach has, therefore, benefits such as low-cost fabrication, moderate handling effort and independence of the concrete waveguide geometry. The performance of a manufactured ceramic WR12 waveguide is compared to a commercial waveguide and a conventionally printed counterpart. For that reason, relevant properties, such as surface roughness and waveguide geometry, are characterized. Parsing the electrical measurements, the ceramic waveguide specimen features an attenuation coefficient of 30–60 dB/m within the E-Band. The measured attenuation coefficient is 200% and 300% higher compared to the epoxy resin and the commercial waveguide and is attributed to the increased surface roughness of the ceramic substrat
Keywords: printing; additive manufacturing (AM); ceramics; rectangular waveguides; rapid prototyping

Additive Manufacturing of Coplanar Transmission Lines on Alumina Substrate up to 24 GHz using Laser Assisted Selective Metallization - Lomakin, Konstantin; Wang, Li; Job, Alexander; Süß-Wolf, Robert; Franke, Jörg; Helmreich, Klaus; Gold, Gerald (2020 50th European Microwave Conference (EuMC), 2021)
This work proposes a novel approach for fabrication of high precision radio frequency circuits on low loss ceramic substrates by an additive manufacturing laser assisted selective metalization process. Coplanar waveguides are realized and measured with a GSG probe setup revealing an attenuation coefficient of approximately 110dB/m at 24 GHz, hence suggesting feasibility of the proposed approach. The simplicity of the process makes it an auspicious candidate for development of future communication and sensor applications due to the combination of high performance substrates and simple fabrication technique, while the required precision for mmWave range and above may be achieved by improving the optical laser system and metal platin

Additive Manufacturing of Side-Coupled Cavity Linac Structures from Pure Copper: A First Concept - Mayerhofer, Michael; Brenner, Stefan; Helm, Ricardo; Gruber, Samira; Lopez, Elena; Stepien, Lukas; Gold, Gerald; Dollinger, Günther (Instruments, 2023)
Compared to conventional manufacturing, additive manufacturing (AM) of radio frequency (RF) cavities has the potential to reduce manufacturing costs and complexity and to enable higher performance. This work evaluates whether normal conducting side-coupled linac structures (SCCL), used worldwide for a wide range of applications, can benefit from AM. A unit cell geometry (SC) optimized for 75 MeV protons was developed. Downskins with small downskin angles (Formula presented.) were avoided to enable manufacturing by laser powder bed fusion without support structures. SCs with different (Formula presented.) were printed and post-processed by Hirtisation (R) (an electrochemical process) to minimize surface roughness. The required accuracy for 3 GHz SCCL (medical linacs) is achieved only for (Formula presented.). After a material removal of 140 µm due to Hirtisation (R), a quality factor (Formula presented.) of 6650 was achieved. This corresponds to 75% of the (Formula presented.) simulated by CST®. A 3 GHz SCCL concept consisting of 31 SCs was designed. The effective shunt impedance (Formula presented.) simulated by CST corresponds to (Formula presented.) and is comparable to the (Formula presented.) of SCCL in use. The reduction in (Formula presented.) expected after Hirtisation (R) can be justified in practice by up to 70% lower manufacturing costs. However, future studies will be conducted to further increase (Formula presented.).
Created from Fastlane, Scopus look-up
Keywords: 3D printing; additive manufacturing; cavity; Gradient Model; Laser Powder Bed Fusion (LPBF); linac; pure copper; RF losses; Selective Laser Melting (SLM); side-coupled cavity linac; surface roughness model

A Distance-Bounding Concept for Bilateral IEEE 802.15.4 Communication - Wittwer, J.; Kirsch, Fabian; Vossiek, Martin (IEEE Conference on Microwaves, Communications, Antennas and Electronic Systems (COMCAS) 2009, 2009)
In this paper a concept for bounding the operation range of IEEE 802.15.4 based wireless sensors is introduced. The distance-bounding is based on a signal round-trip time of flight measurement. For the round-trip time of flight measurement two essential problems have to be solved: on the one hand the time of arrival estimation and on the other hand precise clock synchronization. In our novel approach both challenges were solved by utilizing the preamble and start of frame delimiter (SFD) signal that is available in every IEEE 802.15.4 data package. Based on a Wiener optimal filter applied to the demodulated received IEEE 802.15.4 packet the time of arrival is estimated. The frequency offset is estimated based on the residual frequency of the undemodulated received signal. Exemplary indoor measurements with a system based on a TI CC2430 ZigBEE-Chip prove that the introduced concept allows for a distance-bounding accuracy of approx. 1 m in indoor scenarios with moderate multipath distortion
UnivIS-Import:2015-04-16:Pub.2009.tech.IE.LEH.adista
Keywords: Distance bounding; Distance measurement; Frequency estimation; IEEE 802.15.4; Wiener filtering

A Double-Balanced Diode Mixer with Multi-Decade Bandwidth up to 119 GHz - Schneiderbanger, Dirk; Nezadal, Martin; Sterns, Michael; Rehner, Robert; Martius, Siegfried; Schmidt, Lorenz-Peter (Proceedings of the 1st European Wireless Technology Conference, October, 2008)
We report on a new doubled-balanced diode mixer with multi-decade bandwidth. Our hybrid integrated design is feasible with commercially available components and includes a housing with coaxial connectors. The fundamental mixing conversion loss of our mixer is at most 17 dB from 1 to 46 GHz. Third harmonic mixing conversion loss does not exceed 31 dB between 2 and 119 GHz. Our mixer operates between 500 MHz and 119 GHz with a maximum conversion loss of 31 dB by combining fundamental and third harmonic mixing mode. © 2008 EuMA.
UnivIS-Import:2015-04-16:Pub.2008.tech.IE.LEH.adoubl

A Drone-Based 0.7-4.7 GHz FMCW Radar System for High-Resolution Exploration of Subsurface Glacier Structures - Stelzig, Michael; Benedikter, Andreas; Kleinlein, Micha; Haberberger, Niklas; Krabbe, Lena; Lomakin, Konstantin; Braun, Matthias; Krieger, Gerhard; Vossiek, Martin (2023 IEEE International Radar Conference (RADAR), 2023)
A majority of the studies on subglacial structure mapping and imaging have relied on low-frequency ground penetrating radar (GPR) systems. In particular, mapping alpine glaciers using surface-based high-resolution radar sensors poses a considerable threat to the operators due to crevasses or avalanches; this can be avoided by deploying an unpiloted aerial vehicle (UAV)-based radar sensor. Herein, we present an ultrawideband (UWB) bistatic frequency-modulated continuous-wave (FMCW) GPR for operation on a UAV. By using a UAV equipped with ultrawideband and extremely lightweight additively manufactured horn antennas at a bandwidth of 4GHz between 0.7 GHz and 4.7 GHz we acquired ultra-high-resolution images of the upper firn layers of an alpine glacier. The acquired measurements at the Jungfraufirn, Switzerland illustrate the out-standing performance of the overall system and its applicability in glaciological research.<br
Keywords: Ground penetrating radar; Horn antennas; Radar; Bandwidth; Radar imaging; Radar antennas; Autonomous aerial vehicles; Unpiloted Aerial Vehicle; Frequency-Modulated Continuous-Wave Radar; Horn Antenna; Subsurface Imaging; Glacial Exploration; Ground Penetrating Radar

Advanced Broadband Millimetre-Wave Characterization Techniques of Dielectrics - Gumbmann, Frank; Tran, Hue Phat; Weinzierl, Jochen; Schmidt, Lorenz-Peter (9th European Conference on Nondestructive Testing, Berlin, September, 2006)
UnivIS-Import:2015-04-16:Pub.2006.tech.IE.LEH.advanc

Advanced Microwave Imaging - Ahmed, Sherif Sayed; Schießl, Andreas; Gumbmann, Frank; Tiebout, Marc; Methfessel, Sebastian Dirk; Schmidt, Lorenz-Peter (IEEE Microwave Magazine, 2012)
Due to the enormous advances made in semiconductor technology over the last few years, high integration densities with moderate costs are achievable even in the millimeter-wave (mm-wave) range and beyond, which encourage the development of imaging systems with a high number of channels. The mm-wave range lies between 30 and 300 GHz, with corresponding wavelengths between 10 and 1 mm. While imaging objects with signals of a few millimeters in wavelength, many optically opaque objects appear transparent, making mm-wave imaging attractive for a wide variety of commercial and scientific applications like nondestructive testing (NDT), material characterization, security scanning, and medical screening. The spatial resolution in lateral and range directions as well as the image dynamic range offered by an imaging system are considered the main measures of performance. With the availability of more channels combined with the powerful digital signal processing (DSP) capabilities of modern computers, the performance of mm-wave imaging systems is advancing rapidl
lhft_intern.bib::Ahmed2012c

Advanced Millimeter Wave Radar-Based Human Pose Estimation Enabled by a Deep Learning Neural Network Trained With Optical Motion Capture Ground Truth Data - Engel, Lukas; Müller, Jonas; Rendon, Eduardo Javier Feria; Dorschky, Eva; Krauß, Daniel; Ullmann, Ingrid; Eskofier, Björn; Vossiek, Martin (IEEE Journal of Microwaves, 2025)
This paper presents a deep learning-enabled method for human pose estimation using radar target lists, obtained through a low-cost radar system with three transmitters and four receivers in a multiple-input multiple-output setup. We address challenges in previous research that often relied on extracting ground truth poses from RGB data, which are constrained by the need for 3D mapping and vulnerability to occlusions. To overcome these limitations, we utilized optical motion capture, which is widely recognized as the gold standard for precise human motion analysis. We conducted an extensive optical motion capture study involving various recorded movement activities, which resulted in mmRadPose, a new dataset that enhances existing benchmarks for radar-based pose estimation. This dataset has been made publicly accessible. Building on this approach, we designed an application-tailored radar signal processing chain to generate suitable input for the machine learning algorithm. We further developed an attentional recurrent-based deep learning model, PntPoseAT, which predicts 24 keypoints of human poses using radar target lists. We employed cross validation to thoroughly evaluate the model. This model surpasses previous approaches and achieves an average mean per-joint position error of 6.49 cm with a standard deviation of 3.74 cm on totally unseen test data. This excellent accuracy of the reconstructed keypoint positions is particularly remarkable when you consider that a very simple radar was used for the measurements. Additionally, we conducted a comprehensive analysis of the model's performance by exploring aspects such as network architecture, the use of long short-term memory versus gated recurrent units, input data selection, and the integration of multi-head self-attention mechanism
Keywords: Human pose estimation; radar; optical motion capture; millimeter wave; target list; point cloud; machine learning; deep learning; Radar; Pose estimation; Deep learning; Skeleton; Laser radar; Sensors; Radar measurements; Motion capture; Cameras; Synchronization

Advanced Wireless Local Positioning via Compressed Sensing - Kirsch, Fabian; Gottinger, Michael; Dobrev, Yassen; Vossiek, Martin (IEEE Access, 2018)

Advancing the sensitivity of integrated epoxy-based Bragg grating refractometry by high-index nanolayers - Hessler, Steffen; Knopf, Stefan; Rommel, Mathias; Girschikofsky, Maiko; Schmauß, Bernhard; Hellmann, Ralf (Optics Letters, 2020)
In this Letter, we report on significantly improved surrounding RI sensitivity of epoxy polymer waveguide Bragg grating sensors. Uniform Bragg gratings were generated inside flat rectangular epoxy waveguides near the cutoff regime using standard phase mask excimer laser writing. Thickness controlled nanolayers of high-index titanium dioxide were deposited homogeneously on the waveguide sensor's surface area by repeated reactive sputter processing. Maximum Bragg wavelength shifts as high as 74.22 nm, as well as maximum sensitivities around 523 nm/RI unit corresponding to a minimum RI resolution of 1.9. 10(-6), could be obtained by employing a similar to 75 nm thick titanium dioxide coating. (C) 2020 Optical Society of America
CRIS-Team WoS Importer:2020-10-30

Advancing Ultrahigh-Frequency RFID through Digital Signal Processing [From the Guest Editors' Desk] - Ussmueller, Thomas; Carlowitz, Christian (IEEE Microwave Magazine, 2021)
CRIS-Team Scopus Importer:2021-03-05

A Fast Scanning W-Band System for Advanced Millimetre-Wave Short Range Imaging Applications - Tran, Hue Phat; Gumbmann, Frank; Weinzierl, Jochen; Schmidt, Lorenz-Peter (IEEE National Radar Conference - Proceedings, 2006)
The paper presents the development of a fast scanning W-Band (75-100 GHz) system and a suitable antenna concept for advanced imaging applications. The goal is to obtain a broadband frequency response from a large target area within a short time period. Two typical approaches for the design of a free space millimetre-wave imaging setup will be discussed. The first approach consists of a focused bistatic measurement setup that includes a combination of a conical horn and a dielectric lens in order to focus the beam. The basic idea of the second approach is to use an unfocused measurement setup employing synthetic aperture radar (SAR) algorithms in order to focus the image numerically. Both measurement setups will be discussed with respect to the capability for fast scanning mm-wave imaging systems. Experimental results on planar test objects demonstrate the performance of the developed W-Band system compared to a commercial vector network analyzer (VN

A fast scanning W-band system for advanced millimetre-wave short range imaging applications - Weinzierl, Jochen; Schmidt, Lorenz-Peter; et al. (3rd European Radar Conference, EuRAD 2006, 2007)
The paper presents the development of a fast scanning W-Band (75-100 GHz) system and a suitable antenna concept for advanced imaging applications. The goal is to obtain a broadband frequency response from a large target area within a short time period. Two typical approaches for the design of a free space millimetre-wave imaging setup will be discussed. The first approach consists of a focused bistatic measurement setup that includes a combination of a conical horn and a dielectric lens in order to focus the beam. The basic idea of the second approach is to use an unfocused measurement setup employing Synthetic Aperture Radar (SAR) algorithms in order to focus the image numerically. Both measurement setups will be discussed with respect to the capability for fast scanning mm-wave imaging systems. Experimental results on planar test objects demonstrate the performance of the developed W-Band system compared to a commercial vector network analyzer (VNA). © 2006 EuMA.

A Feasibility Study on the Use of Microwave Imaging for In-Vivo Screening of Knee Prostheses - Root, Konstantin; Ullmann, Ingrid; Seehaus, Frank; Vossiek, Martin (International Microwave Symposium, 2020)
This article provides a concept study on the feasibility of microwave imaging for in vivo screening of knee implants. Using microwave imaging for condition monitoring avoids patients’ exposure to X-ray, which is hazardous to human health. Therefore, investigating the potentials of such a technique is worthwhile. Two essential aspects were investigated in the study: 1) the propagation properties of human tissue and 2) the imaging capabilities of microwave synthetic aperture radar (SAR) for screening polyethylene knee inlays. The first point addresses the challenge of strong absorption in tissue, which contains a high percentage of water. Quantitative investigations were performed. For imaging, SAR with a cylindrical synthetic aperture was constructed to account for the convex geometry of the human knee. An imaging concept that considers material properties and refraction was developed to yield a highly focused image. From the results of the two issues, an imaging concept was deduced that could enable a microwave-based screening of the human knee in the future.

A fiber-optic sensor for microwave field measurements - Schmauß, Bernhard; März, Martin; Ernst, J (CRC CRITICAL REV. IN ENVIRON. CONTROL, 1995)
lhft_intern.bib::thirty_years_LHFT_378

A Fibre-Optic Laser Spectrometer for Sensitive Simultaneous Measurement of CO_2 and CO Gas Concentrations - Engelbrecht, Rainer; Euring, J.; Kuntz, F.; Schmidt, Lorenz-Peter (Proceedings, Sensor 2001 (10th Int. Conf. Sensor 2001, Nürnberg 2001), 2001)
UnivIS-Import:2015-04-16:Pub.2001.tech.IE.LEH.afibre

A Flexible Measurement System for Dielectric Waveguide Charaterization at mmW Frequencies - Distler, Felix; Schür, Jan; Vossiek, Martin (Proceedings of the 48th European Microwave Conference 2018 (EuMC 2018), 2018)

A Foil Flip-Chip Interconnect With an Ultra-Broadband Bandwidth of 130 GHz and Beyond for Heterogeneous High-End System Designs - Pfahler, Tim; Scheder, André; Bridier, Anna; Nagel, Mathias; Vossiek, Martin (IEEE Journal of Microwaves, 2024)
This paper presents an ultra-broadband, low-loss, flexible liquid crystal polymer substrate-to-substrate interconnect with a bandwidth of more than 130 GHz. The transition discontinuity was minimized by maintaining both the reference impedance and the electromagnetic field conformity across the transition from alumina substrate to flip-chip foil. Therefore, more than 600 μm long flexible flip-chip interconnects can be realized for bridging millimeter-wave sub-modules and enabling ultra-broadband heterogeneous system design with a measured return loss of above 20 dB. Furthermore, the interconnect can realize ramp interconnections between monolithic microwave integrated circuits or substrates with different substrate heights due to the flexible foil substrate. Minimum parasitic radiation at the transition is realized through a closely spaced signal-to-ground connection. Furthermore, the robustness of the proposed interconnect against lateral misalignment in the assembly is presented through simulation and measurement. An outstanding insertion loss of less than 0.3 dB per transition over a bandwidth of more than 130 GHz is shown.
CRIS-Team Scopus Importer:2024-08-02
Keywords: Assembly; bond-wire; flip-chip; interconnect; liquid crystal polymer (LCP); measurement and test; monolithic microwave integrated circuit (MMIC); packaging; permittivity; signal transition; surface roughness; system-in-package; transition characterization

A Frequency Selective Surface for Harmonic Suppression in THz-Multipliers - Biber, Stephan; Günther, O.; Bozzi, M.; Perregrini, L.; Fischer, Barbara; Hofmann, Arnd; Jepsen, P. U.; Helmer, Harald; Schmidt, Lorenz-Peter (German Microwave Conference, Ulm, Germany, April, 2005)
UnivIS-Import:2015-04-16:Pub.2005.tech.IE.LEH.afrequ

A Fully Analytic Model of Large Area Silicon p-i-n Photodiodes Verified at Short Wavelengths - Loquai, S.; Bunge, C.-A.; Ziemann, O.; Schmauß, Bernhard; Kruglov, R. (Journal of Lightwave Technology, 2010)
lhft_intern.bib::Loquai10a

A Heterostructure Barrier Charge Swing device for Frequency Multiplication at 306 GHz - Nicolae, B.; Ruf, Marcel; Schür, Jan; Schmidt, Lorenz-Peter; Hartnagel, H. (IEEE MTTS Atlanta June, 2008)
A new type of frequency multiplier which is called Heterostructure Barrier Charge Swing (HBCS) is proposed. It concerns a bunch of charge carriers swinging in a trough between heterojunction barriers. The behavior of the device is simulated and experimentally verified. Efficiencies of 27% for tripler and 14% for quintupler operation are predicted. A split-block mount with planar circuitry is presented to prove tripler operation capabilities from 102 GHz to 306 GHz. © 2008 IEEE.
UnivIS-Import:2015-04-16:Pub.2008.tech.IE.LEH.aheter
Keywords: HBCS; Microstrip circuits; Semiconductor heterojunctions; Sub-millimeter wave generation; Waveguide transitions

A High Resolution 2D Omnidirectional Synthetic Aperture Radar Scanner at K Band - Ali, Faiza; Urban, Alexander; Vossiek, Martin (2010 European Radar Conference (EuRAD), 2010)
In this paper a K-band 360° 2D imaging radar utilizing a synthetic aperture scanning principle is introduced. A small omnidirectional antenna is mounted on a rotating platform to create a circular synthetic aperture. Based on a broadband holographic reconstruction principle a high resolution 360° 2D image is calculated after each turn of the platform. The size of the synthetic aperture and thus the lateral resolution of the imaging system are determined by the diameter of the resulting circular antenna trajectory. In contrast to common radar scanner-concepts that utilize highly directional and thus bulky antennas, the proposed scanner concept has the advantage that it uses a small and lightweight omnidirectional antenna. This results in a much more compact radar system with notably relaxed requirements for the scanning mechanics. In addition it will be shown that the use of an omnidirectional antenna allows for very simple options to transfer energy to the radar on the rotation platform. The performance of the proposed SAR radar scanning method is illustrated with a 24 GHz FMCW radar sensor system.
lhft_intern.bib::Ali2010a

A hybrid broadband microwave triple balanced mixer based on silicon crossed quad diodes - Hrobak, M.; Stein, Wadim; Sterns, M.; Schramm, M.; Schmidt, Lorenz-Peter (42th European Microwave Week, 2012)
Triple balanced mixers (TBM) are ideally suited for use in heterodyne transceivers with great signal bandwidths. The design and construction of a hybrid broadband TBM based on commercial silicon crossed quad diodes is presented. Broadband planar baluns and the use of balanced edge and broadside coupled striplines allow for covering an RF / LO frequency range of 1 GHz to 35 GHz and at least 10 GHz IF bandwidth, if we claim for up- and downconversion loss values below 15 dB. This is achieved with local oscillator power levels PLO ∈ [10,14] dBm and an input 1 dB compression point of 6 dBm. The paper includes spectral measurement data which are in reasonable agreement with the simulation results that are based on a co-simulation procedure between 3D electromagnetic field (EM) simulations and nonlinear harmonic balance circuit simulations.
lhft_intern.bib::hrobakEumwMix

A Hybrid Broadband Millimeter-Wave Diode Ring Mixer with Advanced IF Extraction Technique - Schneiderbanger, Dirk; Cichy, A.; Rehner, Robert; Martius, Siegfried; Sterns, Michael; Schmidt, Lorenz-Peter (Proceedings of the 37th European Microwave Conference, 2007)
We report on a hybrid octave-bandwidth millimeterwave diode mixer with advanced IF extraction. The design uses a reproducible, low cost hybrid technology including thinfilm circuit and flip-chip mounted diode chips. Side coupled Marchand baluns with IF tap provide balanced RF and LO signals as well as serve for extracting the IF signal. Measurement results for fixed, low IF frequency show a conversion loss around 10 dB from 35 to 67 GHz. Furthermore the mixer is suitable for IF frequencies up to 23 GHz. These features allow very flexible applications of the presented mixer in broadband test and measurement systems. © 2007 EuMA.
UnivIS-Import:2015-04-16:Pub.2007.tech.IE.LEH.ahybri

A Joint Radar and Communication Approach Based on Phase-Coded FMCW Chirp Sequences - Alami El Dine, Mohamad; Stelzig, Michael; Schür, Jan; Vossiek, Martin (International Conference on Microwaves for Intelligent Mobility (ICMIM), 2024)
Joint radar and communication (RadCom) systems are an emerging solution to the spectrum congestion problem that has attracted the attention of both scientific and industrial researchers—for example, in the field of autonomous systems. In this contribution, we propose a novel signaling approach utilizing a chirp sequence radar to seamlessly integrate communication capabilities into the system. The concept relies on a correlation-based synchronization and can estimate and compensate phase errors caused by Doppler frequency shifts in the received signals. Measurement results at 25-GHz confirmed the system’s simulated performance.<br
CRIS-Team Scopus Importer:2024-09-06
Keywords: Chirp sequence; PC-FMCW; RadCom.

All-fiber mode-multiplexed transmission of two channels in a single step-index multimode fiber - Schmauß, Bernhard (Microwave and Optical Technology Letters, 1993)
Mode multiplexing, a method for transmitting two signals in one fiber without time‐ or wavelength multiplexing, is presented in theoretically and experimentally. It is shown that two mode‐coded channels can be launched and separated using optical directional couplers with enhanced mode selectivity combined with a simple signal processing unit. © 1993 John Wiley & sons, In
lhft_intern.bib::thirty_years_LHFT_302

All-optical DPSK-Signal-Regeneration based on a NOLM-Setup - Striegler, Arne; Meißner, Markus; Cvecek, Kristian; Sponsel, Klaus; Schmauß, Bernhard (Optical Fiber Technology, 2005)
We present a novel concept for all-optical DPSK signal regeneration based on a directionally attenuated non linear loop mirror (DA-NOLM). © 2005 Optical Society of America.
UnivIS-Import:2015-03-09:Pub.2005.tech.IE.LEH.allopt

All-Optical DPSK Signal Regeneration Based on Cross-Phase Modulation - Striegler, Arne; Schmauß, Bernhard (IEEE Photonics Technology Letters, 2004)
We present a concept for all-optical differential phase-shift keying (DPSK) signal regeneration, which reduces amplitude jitter and preserves phase information. At first, we consider a configuration to regenerate optical signals based on spectral broadening by self-phase modulation (SPM). An analytical approach of the induced phase shift demonstrates why SPM is not suitable for DPSK signal regeneration. We derive conditions for DPSK signal regeneration and present a configuration based on cross-phase modulation. Amplitude jitter is reduced effectively while preserving DPSK phase information. Numerical simulations prove the results and demonstrate the performance of DPSK signal regeneration.
UnivIS-Import:2015-03-09:Pub.2004.tech.IE.LEH.allopt
Keywords: All-optical regeneration; Cross-phase modulation (XPM); Differential phase-shift keying (DPSK); Highly nonlinear fiber (HNLF); Self-phase modulation (SPM)

All Optical Limiter Based on Self Phase Modulation and Dispersive Chirping - Holtmannspötter, Michael; Schmauß, Bernhard (Cleo Juni 2007, 2007)
All optical limiters may constitute the enablers of 3R regeneration for bit rates of 40 Gb/s and above. In M. Daikoku et al. (2006), an all optical limiter is used to enhance the robustness of a cross saturation-based 3R regenerator against surge conditions, whilst in C. Kouloumentas et al. (2006), the limiter equalizes the output of a Fabry Perot filter feeding a clock recovery unit. Furthermore, all optical limiters could mitigate fast power transients caused by data traffic bursts in optical amplifiers (OA). Their suitability for fast events is due to the exploitation of nonlinear optical effects, which are practically instantaneous. We investigated an all optical limiter based on self phase modulation (SPM). The limiter consists of a highly nonlinear fibre (HNLF), two dispersion compensating fibres and an optical band pass filter. Low threshold is achieved by center frequency filtering (CFF) of the SPM-broadened signal spectrum. Negative dispersive chirping optimizes the power transfer characteristic for very low fluctuations in output pulse peak power. Simulations were conducted with and without a fibre transmission span, consisting of 80km of standard single mode fibre (SSMF), the dispersion was compensated by a DCF. The signals were reamplified by an OA. The simulation results of the back-to-back case and the transmission case nearly did not differ. The moderate distortions induced by the limiter in both cases demonstrate the limiter's potential for practical application.
UnivIS-Import:2015-04-16:Pub.2007.tech.IE.LEH.allopt

All-Optical Multilevel Amplitude and Phase Regeneration - Röthlingshöfer, Tobias; Richter, T.; Onishchukov, Georgy; Schubert, C.; Schmauß, Bernhard; Leuchs, Gerd (2014 IEEE Photonics Society Summer Topical Meeting Series, 2014)
Using a cascade of an amplitude and a phase regenerator, multilevel signal processing is demonstrated experimentally for a 25-GBd star-8QAM. Improvements in the signal quality by up to 2 dB are obtaine
lhft_intern.bib::Roethlingshoefer2014_6

All-optical phase-preserving multilevel amplitude regeneration - Röthlingshöfer, Tobias; Richter, Thomas; Schubert, Colja; Onishchukov, Georgy; Schmauß, Bernhard; Leuchs, Gerd (Optics Express, 2014)
The possibility of all-optical phase-preserving amplitude regeneration for star-8QAM is demonstrated using a modified nonlinear optical loop mirror. Experiments show a reduction in amplitude noise on both amplitude levels simultaneously, considering two different types of signal distortions: deterministic low-frequency amplitude modulation and broadband amplitude noise. Furthermore, using this amplitude regeneration, the robustness against nonlinear phase noise from fiber nonlinearity in a transmission line is increased. The scheme suppresses the conversion of amplitude noise to nonlinear phase noise. This is shown for simultaneous amplitude regeneration of the two amplitude states as well as for amplitude regeneration of the high-power states only. If the transmission is limited by nonlinear phase noise, single-level operation at the more critical higher-power state will benefit because of the wider plateau region. Numerical simulations confirm the experimental result

All-optical signal regeneration of advanced modulation formats - Röthlingshöfer, Tobias; Richter, Thomas; Stiller, Birgit; Onishchukov, Georgy; Schubert, Colja; Schmauß, Bernhard; Leuchs, Gerd (Nonlinear Frequency Generation and Conversion: Materials, Devices, and Applications XIII, 2014)
With growing demand on transmission capacity, spectral-efficient multilevel modulation formats such as quadrature amplitude modulation (QAM) become of great interest. One of their weaknesses is high sensitivity to noise accumulation, especially in long-haul transmission systems. Our investigations have shown the possibility of all-optical regeneration of multiple amplitude and phase states. Processing of amplitude noise in several amplitude states is based on periodicity of interference conditions in modified nonlinear fiber Sagnac interferometers. Their staircase-like power transfer characteristic can be used for phase-preserving amplitude regeneration of multiple amplitude states. Processing of QAM with up to three non-zero amplitude states, e.g. 16QAM, has been demonstrated in numerical simulations. Furthermore, simultaneous amplitude regeneration of a star-8QAM format with two amplitude states was performed experimentally. Recently, it has also been shown that phase-sensitive amplification for multiple phase states can be realized in fiber optical parametric amplifiers using four-wave mixing (FWM) with a high-order idler. Our numerical simulations and experimental results for star-8QAM revealed that with some modifications, this approach can be used not only for reduction of phase noise in multilevel phase-shift keying but also for signals with multiple amplitude states. The transmission improvement using a cascade of these two regenerator types has been demonstrated in numerical simulations and experiments. Numerical investigations confirm also the possibility to combine both approaches in a single device by using the highly nonlinear fiber in the Sagnac interferometer loop simultaneously for phase-sensitive amplification in one propagation direction. © (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use onl
lhft_intern.bib::Roethlingshoefer2014_8

All-Optical Simultaneous Multilevel Amplitude and Phase Regeneration - Röthlingshöfer, Tobias; Onishchukov, Georgy; Schmauß, Bernhard; Leuchs, Gerd (IEEE Photonics Technology Letters, 2014)
Simultaneous amplitude and phase noise reduction of multiple signal states using a nonlinear amplifying loop mirror with integrated directional phase-sensitive amplifier are presented for the star-eight quadrature amplitude modulation transmission format as an example. The performance of this combined regenerator scheme is compared with that of a cascade of separate phase and amplitude regenerators. It could be shown that an improvement in the error vector magnitude of 4 dB for the high-power states with simultaneous improvement of 5 dB for the low-power states is possible in both cases. Transmission improvement by regeneration is considered for two noise types: 1) amplified spontaneous emission and 2) nonlinear phase noise. Both schemes can either improve the bit error rate by an order of magnitude or enable an increase of the fiber launch power by 3 d
lhft_intern.bib::Roethlingshoefer2014a

All optical XPM based DPSK signal regeneration - Striegler, A; Schmauß, Bernhard (IEEE Photonics Technology Letters, 2004)
lhft_intern.bib::striegler04

All optical XPM based DPSK signal regeneration - Striegler, A; Wietfeld, A; Schmauß, Bernhard (ECOC 2003, Rimini, Italy, September, 2003)
lhft_intern.bib::striegler03b

A local TX coil for 3T shoulder imaging - Kirsch, Fabian; Schöpfer, Johanna; Huber, Klaus; Biber, Stephan; Martius, Siegfried (2014)

A Low-Loss Bond-Wire Interconnect Design With More Than 130 GHz Bandwidth Enabling an Ultra-Broadband Heterogeneous System Design - Pfahler, Tim; Scheder, André; Bridier, Anna; Schür, Jan; Vossiek, Martin (IEEE Transactions on Microwave Theory and Techniques, 2023)
This article presents a low-loss, ultra-broadband, impedance-controlled bond-wire interconnect interface enabling heterogeneous system design with more than 130 GHz bandwidth. The article focuses on the bond-wire interface design, the substrate arrangement, and the bond-loop specification. Moreover, a robustness analysis of the interconnect regarding assembly tolerances is given. Furthermore, an analysis of parasitic radiation at the interconnect discontinuities is carried out. To account for the dielectric properties of the substrate, the alumina of the demonstrator circuit was precisely characterized. The proposed bond-wire interconnect has been verified up to 135 GHz with a de-embedded insertion loss (IL) of less than of 0.6 dB. A measured return loss (RL) of more than 25 dB over a bandwidth of 130 GHz demonstrates a mmW transparent interconnect, setting a new benchmark for bond-wire interconnect design. In addition, the bond-wire interface is easy to assemble, is insensitive to manufacturing tolerances and thermal expansion, and has a minimal space requirement, thereby providing a cost-effective alternative to flip-chip assemblies.<br
CRIS-Team Scopus Importer:2023-10-13
Keywords: Substrates; Integrated circuit interconnections; Bandwidth; Optical ring resonators; Flip-chip devices; Permittivity; Microwave circuit

A Low Phase-Noise SiGe Colpitts VCO with Wide Tuning Range for UWB Applications - Eßwein, Alexander; Dehm-Andone, Gunther; Weigel, Robert; Aleksieieva, Anna; Vossiek, Martin (2010 European Wireless Technology Conference (EuWIT), 2010)
An integrated differential common collector Colpitts VCO with a wide tuning range is presented in this paper. The circuit was designed and fabricated in the IHP Technologies SGB25V 250nm SiGe:C BiCMOS process. It provides a superior low phase noise performance of −115 dBc/Hz covering the frequency range of 6.7 to 8.7 GHz for UWB pulsed frequency modulated secondary radar application. An additional common collector output buffer was implemented as well. The circuit provides an overall output power of −10dBm single-ended with a power dissipation of 47mW including the on-chip buffer. This paper also shows the modifications and improvements done at the mmwave topology to reduce size and to improve the tuning range.
lhft_intern.bib::Esswein2010

A low power Pulse Frequency Modulated UWB radar transmitter concept based on switched injection locked harmonic sampling - Carlowitz, Christian; Eßwein, Alexander; Weigel, Robert; Vossiek, Martin (7th German Microwave Conference (GeMiC2012), 2012)
Pulse Frequency Modulated ultra-wideband (PFM-UWB) radar signals have been introduced as a very capable option for UWB ranging and wireless local positioning. PFM-UWB signals allow for simple correlating receivers and for a very efficient use of the UWB spectral mask. The generation of pulse frequency modulated (PFM) ultra-wideband (UWB) signals usually requires a fast tunable RF-VCO and good linear RF amplifiers. The resulting complexity and power consumption of a PFM-UWB transmitter can be considered as a drawback compared e.g. to simple impulse radio UWB systems. In this paper, a PFM UWB transmitter concept is introduced that overcomes these drawbacks. The novel approach is based on harmonic sampling with a switched injection locked oscillator (SILO). RF signal generation is solely based on a very simple fixed frequency pulsed LO that samples the phase of an injected harmonic of a baseband FM signal. In this paper the basic concept for switched injection locked harmonic sampling PFM UWB signal generation is introduced and its feasibility is proved through measurements with a 7-8 GHz PFM UWB transmitter prototype.
lhft_intern.bib::Carlowitz2012

A Low-Power, Subharmonic Super-Regenerative Receiver toward a Massive Multichannel FMCW Radar Close to Cut-Off Frequency - Hahn, Leonhard; Vossiek, Martin; Carlowitz, Christian (IEEE MTT-S International Microwave Symposium Digest, 2023)
This paper reports for the first time on an entirely new subharmonic super-regenerative receiver (SRR) concept. Unlike in conventional SRRs, the local oscillator signal is additionally used for non-linear downconversion, enabling phase-coherent amplification. An experimental concept verification is done with a 24 GHz FMCW radar transceiver implemented using planar microstrip technology. It is shown that the subharmonic SRR down-conversion allows to significantly increase the maximum operating frequency and bandwidth. In addition, the LO power requirements are considerably reduced compared to what is typically needed in passive mixer approaches. Operated with a sinusoidal quench signal, the fabricated SRR achieves a gain greater than 60 dB with a power consumption of only 24 mW. It is explained that the concept allows also for operation near the semiconductor cutoff frequency. Due to this, and because of its simplicity, this novel concept is especially suited for scaling to integrated circuits with a high number of receive channels at very high, several 100 GHz, carrier frequencies.
CRIS-Team Scopus Importer:2023-09-01
Keywords: FMCW radar; phase-coherence; subharmonic mixing; super-regenerative receiver

A Method for Extracting an Apparent Permittivity from Band Limited Measurements of Homogeneously Filled Transmission Lines - Bachbauer, Felix; Lomakin, Konstantin; Pfahler, Tim; Gold, Gerald (2022 52nd European Microwave Conference (EuMC), 2022)
This paper introduces a method to extract the apparent permittivity of a transmission line by using only one band limited measurement. This approach can be used for arbitrary cross-section geometries as long as the dielectric filling is homogeneous, therefore extends the method proposed in [1] to determine an initial phase to be capable of dealing with a dielectric filling of a transmission line's cross-section. The group velocity is exploited in its property as a derivative quantity to set up a system of equations, whose solution delivers the initial phase offset -usually lost in band limited measurements- and the apparent permittivity.<br

A Method for the Accumulation of Forward-Looking SAR Images in Automotive Applications - Reinecke, Marc; Noegel, Theresa; Heidbrink, Max; Sura, Oliver; Hoffmann, Marcel; Gulden, Peter; Vossiek, Martin (2024 21st European Radar Conference (EuRAD), 2024)
In the automotive domain, Forward-Looking Synthetic Aperture Radar (FL-SAR) systems can provide environmental perception, overcoming visibility limitations and integration constraints. However, synthesizing high-resolution cumulative maps from individual FL-SAR snapshots can be challenging, because varying target angles and, thus, angular resolutions between snapshots have to be considered. The presented method addresses this challenge by dynamically weighting and accumulating multiple snapshots, enabling the trade-off between prioritizing measurements with higher resolutions and obscurity issues. Our approach rectifies resolution inconsistencies inherent in FL-SAR systems, enhancing the quality of cumulative maps. We provide an overview of FL-SAR measurements and achievable resolution gains compared to static imaging methods. Our measurement results demonstrate the effectiveness of the algorithm in generating seamless maps, which was validated in real-world scenarios. This research aims to advance the role of FL-SAR as a reliable tool for environmental perception and mapping in automotive application

A microwave permittivity sensing system based on a hybrid heterodyne reflectometer circuit - Nehring, Johannes; Schütz, Martin; Weigel, Robert; Kissinger, Dietmar (Microwave Conference (EuMC), 2014 44th European, 2014)

A Millimeter-Wave Low-Power Active Backscatter Tag for FMCW Radar Systems - Strobel, Axel; Carlowitz, Christian; Wolf, Robert; Ellinger, Frank; Vossiek, Martin (IEEE Transactions on Microwave Theory and Techniques, 2013)
In this paper, a fully integrated active backscatter transponder based on the switched injection-locked oscillator (SILO) principle for frequency-modulated continuous-wave radar applications is presented. Furthermore, a method to characterize a SILO amplifier is extended and utilized to measure the system parameters of the presented backscatter tag that operates at 34.45 GHz. It is digitally tunable from 32.7 to 35.4 GHz and reaches an unpulsed output power of 5 dBm. Above injection power levels of-53 dBm, the SILO tag responds phase coherent at its maximum output power. In system measurements, the SILO backscatter transponder was used to perform distance measurements at ranges from 0.7 to 11.5 m. A remarkably good mean distance measurement error of 7 cm with a standard deviation of 10 cm was achieved in a strong multipath environment. The single measurement precision is below 3 mm. © 1963-2012 IEE
UnivIS-Import:2015-03-09:Pub.2013.tech.IE.LEH.amilli
Keywords: Chirp radar; distance measurement; FM radar; frequency-modulated continuous-wave (FMCW) secondary radar; switched injection-locked oscillator (SILO)

A Millimeter-Wave MIMO Radar Network for Human Activity Recognition and Fall Detection - Fröhlich, Ann-Christine; Mejdani, Desar; Engel, Lukas; Bräunig, Johanna; Kammel, Christoph; Vossiek, Martin; Ullmann, Ingrid (2024 IEEE Radar Conference (RadarConf24), 2024)

A MIMO ISAR Approach with Depth Camera Motion Tracking for Improved Imaging in Walk-Through Security Scanners - Root, Konstantin; Gumbmann, Frank; Adametz, Julian; Ullmann, Ingrid; Vossiek, Martin (2023 IEEE International Radar Conference (RADAR), 2023)

A MIMO UHF-RFID SAR 3D Locating System for Autonomous Inventory Robots - Gareis, Matthias; Carlowitz, Christian; Vossiek, Martin (2020 IEEE MTT-S International Conference on Microwaves for Intelligent Mobility, ICMIM 2020, 2020)
As ultrahigh frequency (UHF) radio-frequency identification (RFID) is a cost-efficient, reliable technology, its use for Internet of Things applications is very attractive. The goal of three-dimensional (3D) product maps for smart warehouses is very challenging, but can be achieved with UHF-RFID. Therefore, we equipped a mobile robot platform with a commercial RFID reader and added a switching matrix to integrate a multiple input - multiple output (MIMO) synthetic aperture radar based localization concept (SARFID) with the use of eight antennas. The mobile robot platform and the MIMO localization technique together demonstrate good tag localization results. We evaluate both single-dimensional and two-dimensional synthetic aperture radar (SAR) trajectories. Their shapes are the main contributor to the achievable accuracy. The robot position is acquired by the robot's odometry data. Despite the substantial error in the robot position, we generate 3D product maps with tags labeled on objects and achieve a 3D root mean square error (RMSE) of 3.8 cm.
CRIS-Team Scopus Importer:2021-04-19
Keywords: 3D localization; 3D product map; MIMO; SAR; SARFID; UHF-RFID

A Miniaturized Flexible Surface Electromyography Sensor With an Integrated Localization Concept - Balbach, Samira; Kolpak, Jasmin; Dorn, Christian; Brückner, Stefan; Schlechtweg, Niklas; Gambietz, Markus; Koelewijn, Anne; Vossiek, Martin; Hagelauer, Amelie (IEEE Microwave Magazine, 2025)
Recent developments in sensor technology have allowed researchers to investigate the potential of using human movement measurements for unobtrusive diagnosis and monitoring of prevalent neuromuscular disorders such as Parkinson’s disease (PD) or joint osteoarthritis. Disease diagnosis and monitoring require both information about the movement itself (kinematics) and the muscle forces that drive it (kinetics). Although the movement reflects the impairment, the forces reveal its underlying cause [1]. The millimeter-level tracking accuracy achieved in our previous work within the Collaborative Research Center (CRC) “Empathokinaesthetic Sensor Technology—Sensor Techniques and Data Analysis Methods for Empathokinaesthetic Modeling and Condition monitoring” (CRC 1483 “EmpkinS”) [2] enables the detection of small movement differences. Additionally, recent advances in optimal control [3], [4], [5] and machine learning [6] have enabled the accurate estimation of kinematic and kinetic movement parameters outside of laboratory environments and across various sensor types. These optimal control problems are solved by minimizing an objective related to energy minimization, which replicates the central nervous system’s approach to movement planning [7]. However, this method has been shown to inaccurately predict muscle activity [8]. This inaccuracy is thought to arise from the failure to account for uncertainty and randomness as it is known that optimal muscle contraction differs in environments with randomness compared to those without [9]. Furthermore, the energy optimality of movement might not be a valid assumption in patients with neuromuscular disease, for example, in PD [10
Keywords: Location awareness; Radio frequency; Electrodes; Neuromuscular; Optimal control; Kinematics; Sensor systems; Kinetic theory; Microwave filters; Monitoring

A mm-wave RFID system with locatable active backscatter tag - Carlowitz, Christian; Strobel, Axel; Schafer, Tobias; Ellinger, Frank; Vossiek, Martin (IEEE International Conference on Wireless Information Technology and Systems 2012, 2012)
Precise localization of an object with attached RFID tag is required for many future applications like the internet of things, augmented reality or distributed sensor networks. Especially precise medium range localization in dense multipath environments places high demands on the capabilities of RFID tags, which are severely limited concerning complexity and power consumption. Regarding range coverage, active backscatter transponders significantly reduce path loss in comparison to their passive counterparts. This is particularly important at high frequencies, which are attractive since their regulatory constraints offer larger allocated bandwidths compared to lower frequency bands. Therefore, with mm-wave transponders, ranging resolution, data throughput for RFID communication and multi user capability can be improved without accepting range limiting RF power restrictions like in ultra-wideband systems. In order to achieve a measurement range in the order of 10 m with a tag featuring limited complexity and power consumption, the switched injection-locked oscillator is proposed as backscatter transponder technology, which has already been successfully applied to lower frequency localization systems [2]. In contrast to a simple linear amplifier based approach, it offers much higher single stage gain in the order of about 60 dB when switched on. Furthermore, aliases caused by the switched operation allow suppressing passive reflections of the RFID reader's signal completely. In this paper, a complete 34 GHz FMCW RFID ranging system concept and demonstrator implementation based on the switched injection-locked oscillator are demonstrated for the first time. The theoretical expectations regarding the operation principle are verified experimentally and the performance of the demonstrator implementation is evaluated. Measurement results in an indoor multipath indoor environment deliver an accuracy of about 3 cm within a range of 1 to 6
lhft_intern.bib::Carlowitz2012c

A Mode Calculation Procedure for Unstable Waveguide Resonators Ein Berechnungsverfahren für optisch instabile Wellenleiter-Resonatoren - Hocke, Ralf; März, Martin (Frequenz, 1995)
Es wird ein neues Verfahren zur Berechnung optisch instabiler Wellenleiter-Resonatoren vorgestellt. Die dispcrsiven Eigenschaften des Wellenleiters werden durch eine Entwicklung des Feldes in die Feldtypen des Wellenleiters berücksichtigt, diese Feldtypen werden über die Spiegel verkoppelt. Ein Vergleich der Ergebnisse mit den Resultaten bekannter Verfahren zeigt eine gute Übereinstimmung. © 1995, Walter de Gruyter. Alle Rechte vorbehalten.
Created from Fastlane, Scopus look-up

A Modular MIMO Millimeter-Wave Imaging Radar System for Space Applications and Its Components - Hrobak, Michael; Thurn, Karsten; Moll, Jochen; Hossain, Maruf; Shrestha, Amit; Thualfiqar, Al-Sawaf; Stoppel, Dimitri; Weimann, Nils G.; Rämer, Adam; Heinrich, Wolfgang; Martinez, Javier; Vossiek, Martin; et al. (Journal of Infrared, Millimeter, and Terahertz Waves, 2020)
This article presents the design and prototyping of components for a modular multiple-input-multiple-output (MIMO) millimeter-wave radar for space applications. A single radar panel consists of 8 transmitters (TX) and 8 receivers (RX), which can be placed several times on the satellite to realize application-specific radar apertures and hence different cross-range resolutions. The radar chirp signals are generated by SiGe:C BiCMOS direct-digital-synthesizers (DDS) in the frequency range of 1 to 10.5GHz with a chirp repetition rate of <1μs within each TX and RX. The latter allows for easy interfaces in the MHz range in between the TX/RX units and therefore optimized 2-D sparse antenna arrays with rather large distances in between the TX/RX antennas. Furthermore, this allows for ideally linear frequency modulated continuous-waveforms (FMCW) in conjunction with phase-shift-keying (PSK) radar signals and enables simultaneous operation of all TX when code division multiplex (CDMA) modulation schemes are applied. Comparably low complexity of the TX/RX units has been achieved by applying straightforward frequency plans to signal generation and detection but comes with challenging requirements for the individual active and passive components. Tackled by thin film technology on alumina and the recently developed SiGe and InP semiconductor technologies, which have been further optimized in terms of process maturity and space qualification. Upconversion and downconversion to and from 85 to 94.5GHz are performed by double balanced Gilbert mixers realized with InP double heterojunction bipolar transistor technology (DHBT) and 42-GHz local oscillator signals from SiGe:C BiCMOS VCO synthesizer using phase-locked-loops (PLL). InP DHBT power amplifiers and low-noise amplifiers allow for output power levels of 15dBm and >30dB gain with noise figure values of 9dB, respectively. The MIMO radar utilizes patch antenna arrays on organic multilayer printed circuit boards (PCB) with 18dBi gain and 18∘ half power beamwidth (HPBW). Generation of power supply and control signals, analog-to-digital conversion (ADC), and radar signal processing are provided centrally to each panel. The radar supports detection and tracking of satellites in distances up to 1000m and image generation up to 20m, which is required to support orbital maneuvers like satellite rendezvous and docking for non-cooperative satellites.

A Modular Vector Field Measurement System at 150 GHz, 300 GHz and 450 GHz - Hofmann, A.; Seibert, Günter; Manglberger, M.; Kalb, A.; Göbel, S.; Yao, S.; Weinzierl, Jochen; Schmidt, Lorenz-Peter; Brand, Hans (Proceedings of GeMiC, April, 2005)
UnivIS-Import:2015-04-16:Pub.2005.tech.IE.LEH.amodul

A monolithically stabilized voltage controlled oscillator for the millimeter wave range - Güttich, U.; Dieudonne, J.; Schmidt, Lorenz-Peter (1993)

Amplitude noise reduction in multilevel QAM formats using a nonlinear amplifying loop mirror with a saturable amplifier - Roethlingshoefer, Tobias; Onishchukov, Georgy; Schmauß, Bernhard; Leuchs, Gerd (Lasers and Electro-Optics Europe (CLEO EUROPE/EQEC), 2011 Conference on and 12th European Quantum Electronics Conference, 2011)
lhft_intern.bib::Roethlingshoefer2011

A Multi-channel Frequency-variable Test Signal Generator for SSR Signals - Trommer, Ralph; Quednau, Philipp; Schmidt, Lorenz-Peter (43th European Microwave Week, 2013)
Secondary surveillance radar is an important part of air traffic control nowadays. Modern receivers use an antenna array to estimate the direction of the arriving signal in order to increase the reliability of the received aircraft positions. In this paper a versatile multi-channel signal generator for testing these receivers is presented. The requirements for such a system are explained followed by the description of the hardware and software design and the automatic self calibration process. Finally the measurement results of the output signals are presented. © 2013 EMA.
UnivIS-Import:2015-04-16:Pub.2013.tech.IE.LEH.amulti

A Multi-Channel Radiometer with Focal Plane Array Antenna for W-Band Passive Millimeterwave Imaging - Richter, Johannes; Nötel, D.; Klöppel, F.; Huck, J.; Essen, H.; Schmidt, Lorenz-Peter (IEEE, IMS 2006, Juni, 2006)
Passive millimeter wave imaging can complement security measures in scenarios such as airports or checkpoints, due to the fact that these frequencies penetrate clothes and enable e.g. concealed weapon detection (CWD). Such a radiometric system has to meet several key requirements concerning its thermal and spacial resolution and the image acquisition time. The latter can be reduced significantly by scanning the scene with multiple beams simultaneously, The demonstrator system presented in this paper describes a multi-channel focal plane array (FPA) approach that cuts the overall scanning time down by a factor of four. Dielectric rod antennas are proposed as feed elements in high density arrays. The dielectric wide angle lens of the FPA is focused at a distance of 20 m for stand-off measurements. Besides addressing the design and characterization of both the antenna setup and the radiometric receivers, measurement results are presented to demonstrate the feasibility of the multi-channel concept. © 2006 IEEE.
UnivIS-Import:2015-04-16:Pub.2006.tech.IE.LEH.amulti

A Multilateral Synthetic Aperture Wireless Positioning Approach to Precise 3D Localization of a Robot Tool Center Point - Li, Gang; Vossiek, Martin (IEEE Radio Wireless Week 2011, IEEE Topical Conference on Wireless Sensors and Sensor Networks, 2011)
lhft_intern.bib::Li2011

A Multimodal Radar-Ultrasound Imaging Concept for Improved Display of Concealed Objects - Ullmann, Ingrid; Körner, Georg; Adametz, Julian; Vossiek, Martin (IEEE Access, 2019)
Subsurface radar imaging provides an insight into hidden scenes: For example, in security screening, radar can be used for the detection of dangerous objects or contraband. In non-destructive testing, radar imaging also allows to find internal material defects such as cracks or contaminations. Object contours and internal structures appear as echoes in the radar receive signal. The strongest echo typically is the one from the test object’s surface. This echo can mask smaller echoes close to the surface and therefore, small inner structures may become invisible in the reconstruction image. To overcome this problem, we propose a novel concept to eliminate the surface echo in radar imaging. In contrast to existing surface elimination techniques, our approach can be used not only when screening objects with planar surfaces, but also on such that exhibit an unknown and possibly non-planar profile. Our approach is to combine radar and air-coupled ultrasound. Since air-coupled ultrasound cannot penetrate into solids, the receive signal only contains the echo from the test object’s surface. The core of our concept is to generate radar and ultrasound signals with the same characteristics, i.e. they are equal in amplitude and phase. Then, the ultrasound data can be subtracted from the radar data and the resulting signal will only contain the echoes of the inner structures. When processing this data, the reconstructed images are almost free of reflections from the surfac

A Multiple Domain Characterisation and Test Method for Discontinous Signal Paths - Helmreich, Klaus (Proceedings, 2006)
UnivIS-Import:2015-04-16:Pub.2006.tech.IE.c3scha.amulti

An Active Self-Interference Cancellation Coupler with 60 dB Isolation Applied in a 24 GHz SFCW Radar - Fenske, Patrick; Kögel, Tobias; Scheder, André; Root, Konstantin; Carlowitz, Christian; Vossiek, Martin (2023 IEEE/MTT-S International Microwave Symposium - IMS 2023, 2023)
This work introduces a compact planar implementation of a self-interference cancellation coupler (SICC), which is designed for 24 GHz continuous wave (CW) radar frontends. The SICC utilizes a part of the TX signal which is modulated in amplitude and phase to generate a cancellation signal, which suppresses the most severe TX-RX-leakage components. Instead of using a closed control loop to minimize leakage, an approach with precise offline calibration is used. We showed the reproducibility of this approach with repeated isolation measurements applying the calibrated control values for the cancellation modulator. With this approach an isolation of about 60 dB in a range of 23.0 GHz to 24.25 GHz is achieved. A further novelty of this work is the implementation of the RF domain canceller in a monostatic radar setup to investigate the influence of TX leakage and the improvements that come with the SICC in the presence of close weak reflecting targets by analyzing the respective IF spectrum. The results of the stepped-frequency continuous wave (SFCW) radar measurements show a significant reduction of the leakage peaks in the IF spectrum as well as an increase of the target peak amplitude, allowing a more secure detection of close targets and reducing the effect of RX frontend saturation.<br
Keywords: Radio frequency; Interference cancellation; Radar measurements; Radar; Couplers; Switches; Receivers

An Additively Manufactured 300 GHz Dielectric Rod Antenna Packaging for Sub-THz Radar Camera Applications - Hahn, Leonhard; Bader, Tobias; Pfahler, Tim; Gloßner, Maximilian; Vossiek, Martin (EuCAP 2025 - 19th European Conference on Antennas and Propagation, 2025)
This paper presents a novel, 3D-printed dielectric packaging approach for application as sub-THz antenna-inpackage (AiP) solution. The application of the dielectric AiP to an on-chip antenna results in a considerable enhancement in gain and efficiency when compared to non-packaged antennas. In comparison to more complex LTCC- or glass-based packaging solutions, the proposed dielectric AiP requires only a single material that can be produced at a low cost and with minimal effort through the use of 3D-printing. Due to the homogeneity of the package, system complexity is significantly reduced. The AiP approach is benchmarked against conventional dielectric rod antennas, which were also fabricated and characterized as part of this work. This is essential for sub-THz radar camera systems, whose low gain on-chip antennas are usually insufficient. The package approach also provides increased chip protection, as well as cost-effective manufacturing and greatly simplified assembly.
CRIS-Team Scopus Importer:2025-06-20
Keywords: 3D-printing; dielectric waveguide; On-chip antenna; packaging; sub-THz

An Advanced Concept for Coherent Ultra-Low Phase-Noise Clock, LO and Trigger Generation & Distribution in 6G Massive-MIMO Systems - Scheder, André; Witte, Lukas; Rottinghaus, Jonas; Gröschel, Patrick; Karle, Christian; Neu, Marc; Nuss, Benjamin; Vossiek, Martin (2024 54th European Microwave Conference (EuMC), 2024)
The current development of the 6G mobile communications standard shows that in addition to an increase in data rate, a reduction in latency and completely new functionalities such as joint-communication and sensing (JCAS) could become an integral part of the standard. One approach to achieving these goals is massive multiple-input multiple-output (MIMO) systems, whereby both higher energy and bandwidth efficiency can be achieved per device and the entire system itself becomes more resilient. With regard to JCAS, the high number of channels enables a more precise position estimation of the objects to be detected. At the same time, the extremely high number of channels also enforces new requirements for the hardware, as, for example, all channels must be phase-coherent and synchronous. This requirement extends from the clock signal for the digital-to-analog and analog-to-digital converters, to the local oscillators for the mixers, to the trigger signal, which ensures that all system components start at the same time. The backplane system presented in this paper supplies all signals required for the phase-coherent operation of a massive MIMO system while simultaneously achieving ultra-low phase noise even across several master-slave modules.
CRIS-Team Scopus Importer:2024-12-13
Keywords: 6G mobile communication; Phase noise; Local oscillators; System testing; Spectral efficiency; Backplanes; Massive MIMO; Synchronization; Standards; Clocks; 6G; massive MIMO; clock distribution; phase coherency

Analysis and application of digital backward propagation in high bit-rate optical transmission systems - Asif, Rameez (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2012)
UnivIS-Import:2018-09-06:Pub.2012.tech.IE.LEH.analys

Analysis and Optimization of SPM-based 2R Signal Regeneration at 40 Gb/s - Striegler, Arne; Schmauß, Bernhard (Journal of Lightwave Technology, 2006)
In order to maintain a signal quality and to enhance the robustness of long haul transmission, optical regenerators have been developed and investigated during the last few years. This paper provides a detailed analysis of self-phase modulation (SPM)-based 2R signal regeneration by an analysis of the spectrum of a single pulse. A model is presented to explain the principle of ghost-pulse suppression and amplitude-jitter reduction and to derive design rules to optimize signal regeneration at 40 Gb/s. Finally, the influence of the fiber dispersion on the regeneration is discussed. © 2006 IEEE.
UnivIS-Import:2015-03-09:Pub.2006.tech.IE.LEH.analys
Keywords: All-optical regeneration; Nonlinear-fiber (NLF) effects; Self-phase modulation (SPM)

Analysis of phase sampling noise of switched injection-locked oscillators - Strobel, Axel; Schulz, Markus; Ellinger, Frank; Carlowitz, Christian; Vossiek, Martin (IEEE Radio Wireless Week 2014, 2014)
In this paper, a fully integrated active backscatter transponder based on the switched injection-locked oscillator (SILO) principle for frequency modulated continuous wave (FMCW) radar applications is presented. Furthermore, a novel theory to model the phase sampling behaviour of a SILO, accounting for noisy injection signals, is derived. The presented backscatter tag operates at 34.5 GHz and reaches a steady-state output power of 7 dBm. The input referred noise power of the SILO is -66 dBm. In system measurements, a remarkably good accuracy of 5 cm and a precision better than 2 mm was achieved in an indoor environment at ranges from 0.7 m to 17 m. In outdoor measurements an accuracy of 2 cm and a precision 1 cm was achieved for ranges from 45 m to 103 m. © 2014 IEE
UnivIS-Import:2015-04-16:Pub.2014.tech.IE.LEH.analys_5
Keywords: Chirp radar; distance measurement; FM continuous wave (FMCW) secondary radar; frequency modulated (FM) radar; input referred noise power; phase sampling; switched injection-locked oscillator

Analysis of SBS gain shaping and threshold increase by arbitrary strain distributions - Engelbrecht, Rainer (Journal of Lightwave Technology, 2014)
Fibers with a longitudinal strain distribution can be used to shape the stimulated Brillouin scattering (SBS) gain spectrum or to increase the SBS threshold power. Theoretical analysis and experimental results on the SBS gain spectrum of coiled fibers with a continuous and arbitrary distribution of longitudinal strain are presented. The concept of a critical gain factor for determining the SBS threshold power with a simple formula is reviewed for fibers with different parameters and spectral shapes. A fiber coiling machine for high coiling forces is described for realizing permanent strain distributions with a maximum strain of more than 3%. SBS spectra were broadened to a spectral width of 1.7 GHz. Measurements verify a significant SBS gain suppression by a factor of 40, which is in excellent agreement with the theoretical analysis. Finally, synthetic triangular and broadened Lorentzian SBS spectral shapes with a spectral width of 550 MHz are demonstrated. The results can be used to suppress SBS in high-power fiber lasers and amplifiers or to tailor almost any arbitrary SBS spectral shapes, which could be useful for slow-light or active optical filter applications. © 2014 IEEE.
UnivIS-Import:2015-03-09:Pub.2014.tech.IE.LEH.analys
Keywords: Brillouin scattering threshold; fiber amplifiers; fiber lasers; fiber nonlinear optics; slow light; strain

Analysis of the behavior of electric vehicle charging stations with renewable generations - Lee, William; Xiang, Lin; Schober, Robert; Wong, Vincent W.S. (2013 IEEE International Conference on Smart Grid Communications, SmartGridComm 2013, 2013)
In this paper, we study the competitive interactions between electric vehicle charging stations (EVCSs) with renewable electricity generation facilities (REGFs). As electric vehicles (EVs) become more popular, there will be a competition between neighboring EVCSs to attract more EVs. Therefore, an EVCS is likely to set its electricity price by taking into account the competition with neighboring EVCSs, such that its revenue is maximized. We model the competitive interactions between EVCSs by using game theory. In this paper, we show that the game played by EVCSs is a supermodular game and there exists a unique pure Nash equilibrium for best response algorithms with arbitrary initial policy. Simulation results confirm the convergence of the game between EVCSs. The results also verify that it is beneficial for both EVs and EVCSs to have REGFs and all EVCSs will have REGFs in the long run. © 2013 IEEE.
CRIS-Team Scopus Importer:2020-02-03

Analytical Study about the Impact of Multipath Propagation on UHF-RFID Ranging Techniques - Kirsch, Fabian; Miesen, Robert; Vossiek, Martin (IEEE International Conference on Wireless Information Technology and Systems 2012, 2012)
Given the narrow bandwidth of UHF-RFID it is not possible to separate the different signal paths apart. In this paper the SNR was derived, necessary for any nonlinear super-resolution algorithms. As long as these SNR levels are not met, any evaluation method will give a weighted mean of all the individual paths that exist in the perceived channel. Evaluation methods that use only one of 'RSSI' and 'phase' will even be worse. In order to open the possibilities of multipath resistant single-antenna ranging to the field of UHF-RFID applications new regulations or technologies with greater bandwidths are unavoidable. © 2012 IEE
UnivIS-Import:2015-04-16:Pub.2012.tech.IE.LEH.analyt

Analytical Waveguide Model Precisely Predicting Loss and Delay Including Surface Roughness - Lomakin, Konstantin; Gold, Gerald; Helmreich, Klaus (IEEE Transactions on Microwave Theory and Techniques, 2018)
This paper describes an accurate modeling approach taking into account the impact of surface roughness on both the attenuation and the phase coefficients of the propagating TE10 mode in rectangular waveguides. The proposed approach is based on a transmission line model for waveguides and a general surface roughness model, which are both derived from physical relations, i.e., Maxwell’s equations. Thus, it is neither limited to explicit frequency bands nor to certain surface profiles. Based on the proposed approach, the specific influence on the propagation coefficient and the line impedance of a waveguide is quantified in the typical transmission frequency region and also around the cutoff frequency. Also, the roughness-dependent shift of the cutoff frequency is covered by the proposed model and explained analytically. Propagation characteristics predicted by the proposed approach absolutely coincide with full-wave simulation by CST Microwave Studio with the same input parameters. Furthermore, WR10 waveguide samples are fabricated and their surface profile is characterized using a confocal laser scanning microscope. Model predictions agree with electrical measurements up to 90 GHz for the attenuation coefficient within ≤10% and within 0.08% for the phase coefficient in the transmission region of the waveguides. In addition, the difference between normally distributed and arbitrarily distributed surface profiles is covered by the model and pointed out in this paper at rigorous measurements even at very smooth surfaces with root mean square-roughness of less than 300 nm. Finally, different techniques for utilization of this approach and possible application fields are presente

An Efficient yet High-Performance Method for Precise Radar-Based Imaging of Human Hand Poses - Bräunig, Johanna; Wirth, Vanessa; Stamminger, Marc; Ullmann, Ingrid; Vossiek, Martin (2024 21st European Radar Conference, EuRAD 2024, 2024)
Contactless hand pose estimation requires sensors that provide precise spatial information and low computational complexity for real-Time processing. Unlike vision-based systems, radar offers lighting independence and direct motion assessments. Yet, there is limited research balancing real-Time constraints, suitable frame rates for motion evaluations, and the need for precise 3D data. To address this, we extend the ultra-efficient two-Tone hand imaging method from our prior work to a three-Tone approach. Maintaining high frame rates and real-Time constraints, this approach significantly enhances reconstruction accuracy and precision. We assess these measures by evaluating reconstruction results for different hand poses obtained by an imaging radar. Accuracy is assessed against ground truth from a spatially calibrated photogrammetry setup, while precision is measured using 3D-printed hand poses. The results emphasize the method's great potential for future radar-based hand sensing.
CRIS-Team Scopus Importer:2024-12-13
Keywords: FSK radar; gesture recognition; hand pose estimation; radar imaging; three-frequency principle

A new 140 GHz planar diode finline mixer for radiometer applications - Kirsch, Fabian; Boheim, M.; Schmidt, L.; Ritter, J.; Brankovic, V.; Bayer, R.; Arndt, F.; Klein, U.; Künzi, K.; Schwab, G.; Crowe, TW. (1994)

A new Structural Approach for Uniform Sub-Micrometer Anode Metallization of Planar THz Schottky Components - Cojocari, O.; Mottet, B.; Rodriguez-Girones, M.; Biber, Stephan; Marchand, L.; Schmidt, Lorenz-Peter; Hartnagel, H. (Semiconductor Science and Technology, 2004)
This paper presents the evaluation of a Schottky contact technology based on electrochemical metal deposition. The results of a long-term systematic investigation and optimization of the anode formation process to improve the yield and performance of Schottky-based GaAs mixer diodes are detailed. Surface preparation prior to the Schottky-metal deposition and anode metallization as previously optimized for whisker-contacted diodes are successfully transferred to the fabrication of planar structures. This uses an auxiliary honeycomb array of anode-like structures called 'dummy anodes', which are processed simultaneously with the real anodes and then removed in the later technological processes. Consequently, the scattering of planar diodes electrical parameters is significantly reduced and the yield of the fabrication process increases from about 5% up to about 50%. Very good dc characteristics such as series resistance (R s) below 8 Ω, ideality factor (η) below 1.2 and saturation current (I sat) of the order of 10 -17 A are achieved for the anode diameter as small as 1 μm. An excellent IF-noise figure of 250 K at 4.8 GHz up to 280 K at 2.1 GHz with current bias up to 3 mA is obtained for non-cooled THz mixer planar diodes. The use of this technological approach has enabled the extraction of statistically significant data which have been used to characterize the criticality of each step of the fabrication process on the device performance.
UnivIS-Import:2015-03-09:Pub.2004.tech.IE.LEH.anewst

A New Switch Correction Method for a Single-Receiver VNA - Schramm, Marcus; Hrobak, Michael; Schür, Jan; Schmidt, Lorenz-Peter (Proceedings of the 43th European Microwave Week, 2013)
Single receiver vector network analyzers (VNA) are offering a cost efficient possibility to measure complex scattering parameters. One main drawback of this architecture is the larger required period of time to complete the measurement, due to the sequential capturing of the wave quantities. In order to reduce this handicap, a new switch correction scheme is detailed in this paper. The discussion includes a comparison to alternative methods based on measurements and simulations. © 2013 European Microwave Association.
UnivIS-Import:2015-04-16:Pub.2013.tech.IE.LEH.anewsw

A New Technology for Precise Local Position Measurement - LPM - Stelzer, Andreas; Fischer, Alexander; Vossiek, Martin (International Microwave Symposium, 2004)
Precise measurement of the local position of moveable targets in three dimensions is still considered to be a challenge. With the presented local position measurement (LPM) technology a novel system, consisting of small and lightweight measurement transponders and a number of fixed base stations, is introduced. The new system is operating in the 5.8 GHz ISM-band and can handle up to 1000 measurements per second with accuracies down to few centimeters. Measurement results obtained with prototype boards demonstrate the feasibility of the proposed technology in practical applications. There exist a broad range of various applications, such as tracking of persons or controlling autonomous vehicles in industrial or logistic applications.
UnivIS-Import:2015-04-16:Pub.2004.tech.IE.LEH.anewte
Keywords: FMCW; GPS; LPM; Position measurement; Positioning

An Extended Kalman Filter for Direct, Real-Time, Phase-Based High Precision Indoor Localization - Lipka, Melanie; Sippel, Erik; Vossiek, Martin (IEEE Access, 2019)
Radio-based indoor localization is currently a very vibrant scientific research field with many potential use cases. It offers high value for customers, for example, in the fields of robotics, logistics and automation, or in context-aware IT services. Especially for autonomous systems, dynamic human-machine interaction or augmented reality applications, precise localization coupled with a high update rate are key. In this paper, we present a completely novel localization concept whereby received radio signal phase values that are fed into an Extended Kalman Filter (EKF) without any preprocessing are evaluated. Standard preprocessing steps, like angle-of-arrival (AOA) estimation, beamforming, time-of-flight (TOF) or timedifference- of-arrival (TDOA) estimations are not required with this approach. The innovative localization concept benefits from the high sensitivity of radio signals’ phase to distance changes and the fast and straightforward recursive computation offered by the EKF. It completely forgoes the computational burden of other phase-based high-precision localization techniques, like synthetic aperture methods. To verify the proposed method, we use an exemplary setup employing a 24 GHz frequency modulated continuous wave (FMCW) single input multiple output secondary radar with 250 MHz bandwidth. A high precision 6-axis robotic arm serves as a 3D positioning reference. The test setup emulates a realistic industrial indoor environment with significant multipath reflections. Despite the challenging conditions and the rather low bandwidth, the results show an outstanding localization 3D RMSE of around 1.7 cm. The proposed method can easily be applied to nearly any type of radio signal with CW carrier and is an attractive alternative to common multilateration and multiangulation localization approaches. We think it is a quantum leap in wireless locating, as it has the potential for precise, simple and low-cost wireless localization even with standard narrowband communication signals.<br

An Improved Switched Injection-Locked Oscillator for Ranging and Communication Systems - Eßwein, Alexander; Carlowitz, Christian; Vossiek, Martin; Weigel, Robert; Ußmüller, Thomas (43rd European Microwave Conference, 2013)
This paper describes an improved integrated switched injection-locked oscillator (SILO) circuit for use in pulsed angular modulated ultra wideband communication and radar systems, implemented in a 0.25 μm SiGe:C BiCMOS technology. The circuit consists of two active baluns for single-ended to differential and differential to single-ended conversion, a Schmitt-trigger with two pulse generators based on current-starved voltage controlled delay lines and inverter chains and a simple Q-degenerated cross-coupled oscillator for signal generation. It has an externally controllable pulse repetition rate and duration. The previous works of the authors [1] was severely improved in the area of required locking power and pulse duration control. Required injection power has been reduced to -65 dBm. During operation it consumes combined 40mA from 3.3V analog and 2.5V digital supply voltage, while generating a 370mV pp signal. The generated signal has a 10 dB-bandwidth ofs over 2.3 GHz at 6.8 GHz center frequency. Measurement results are shown. © 2013 European Microwave Association.
UnivIS-Import:2015-04-16:Pub.2013.tech.IE.LEH.animpr
Keywords: Injection-Locking; Integrated Circuit; Pulse Generation; Pulsed Frequency Modulated Radar; Radar; VCO

An improved ultra-low-phase noise tunable YIG oscillator operating in the 6–12 GHz range - Stein, Wadim; Huber, Florian; Bildik, Saygin; Aigle, Michael; Vossiek, Martin (47th European Microwave Conference (EuMC), 2017)
This paper presents the improvement of a conventionally designed state-of-the-art yttrium-iron-garnet tuned oscillator with the main focus on the minimization of the phase noise. The employment of modern CAD tools allows for accurate oscillator optimization resulting in a phase noise performance below -133 dBc/Hz at a frequency offset of 100 kHz over the entire range of 6-12 GHz. The presented oscillator is modeled as a one-port oscillator employing a SiGe hetero bipolar transistor as a reflection amplifier and a loop-coupled YIG sphere resonator, modeled and simulated in a commercial FEM 3D-fullwave simulator considering all coupling effects and respective parasitics. The achieved phase noise is compared to a number of state of the art YIG oscillators around the frequency offset of 10 kHz, 100 kHz and 1 MHz. Finally some further phase noise improvements over the frequency range of 6-12 GHz are show
lhft_intern.bib::Stein2017

An Indoor Positioning System Based on Wireless Range and Angle Measurements Assisted by Multi-Modal Sensor Fusion for Service Robot Applications - Dobrev, Yassen; Gulden, Peter; Vossiek, Martin (IEEE Access, 2018)
The current trend for automation is expected to a strongly growth in the area of service robotics. One of the main challenges for reliable operation of such systems is the measurement of the mobile robot pose in a given coordinate system. We present an alternative approach to indoor localization of mobile robots based on the sensor fusion of secondary radar data with an ultrasonic sensor and odometry. The main advantage of the proposed system is that it requires only minimum infrastructure and provides an absolute localization reference to increase the accuracy and reliability. Measurement campaigns in a university building, a hospital, and an office building demonstrate a very good localization performance and prove the advantage of this approac
lhft_intern.bib::Dobrev2018c

An Initialization Method for Ultra-Precise Holographic Wireless Local Positioning - Brückner, Stefan; Sippel, Erik; Gröschel, Patrick; Hehn, Markus; Vossiek, Martin (2023 20th European Radar Conference (EuRAD), 2023)

An Integrated 435 GHz-Quasi-Optical Frequency Tripler - Shaalan, M; Steup, D; Grueb, A; Simon, A; Lin, C; Vogt, A; Krozer, V; Brand, Hans; Hartnagel, H (1996)
lhft_intern.bib::thirty_years_LHFT_395

An Integrated Switched Injection-Locked Oscillator for Pulsed Angle Modulated Ultra Wideband Communication and Radar Systems - Eßwein, Alexander; Carlowitz, Christian; Fischer, Georg; Vossiek, Martin; Weigel, Robert; Ußmüller, Thomas (IEEE International Conference on Ultra-Wideband, ICUWB 2012, 2012)
This paper describes an integrated switched injection-locked oscillator (SILO) circuit for use in pulsed angular modulated ultra wideband communication and radar systems. The circuit consists of two active baluns for single-ended to differential and differential to single-ended conversion, a Schmitt-trigger with modified current mirror load for current peak generation and a simple cross-coupled oscillator for signal generation. It has an externally controllable pulse repetition rate and a pulse duration of approx. 1ns. During operation it consumes 33mA at 3.3V supply voltage, while generating a 370 mVpp signal. The generated signal has a 10dB-bandwidth of over 2GHz at 7.5 GHz center frequency. Measurement results with an external baseband generator are shown. © 2012 IEEE.
UnivIS-Import:2015-04-16:Pub.2012.tech.IE.LEH.aninte
Keywords: Injection-Locking; Integrated Circuit; Pulse Generation; Pulsed Frequency Modulated Radar; Radar; VCO

An Iterative Extended Kalman Filter for Coherent Measurements of Incoherent Network Nodes in Positioning Systems - Hehn, Markus; Sippel, Erik; Vossiek, Martin (IEEE Access, 2020)
Many positioning and tracking applications use spatially distributed sensor stations, each equipped with coherent measurement channels. The coherent data set of each node is incoherently measured to the data sets of all other nodes, avoiding expensive synchronization procedures between the stations. Usually, the measurements are evaluated by mapping the incoherently measured complex valued data on real valued data like angle of arrival or received signal strength. After this preprocessing step, recursive filters fuse the real valued data to estimate a system state. Unfortunately, even though the original measurements are performed in additive white Gaussian noise environments, the preprocessing step can result in correlated, noise shaped errors, whose variance is system state dependent. Hence, the additive white Gaussian noise assumption, which is commonly drawn in Kalman filters, is violated. Therefore, this paper proposes an iterative extended Kalman filter, which estimates the state of a nonlinear real valued system via a complex valued measurement model that consists of incoherent sensor stations, each with several coherent measurement channels. Since the proposed iterative extended Kalman filter is well suited for distributed positioning systems with several stations, a transmitter is localized in a simulation via two sensor stations, each measuring the received signal’s amplitude and phase at four channels. To illustrate the advantages of the proposed algorithm, the direct measurement evaluation using the proposed algorithm is compared to a Kalman filter that evaluates the received signal strengths and angle of arrivals at each sensor station. Finally, a reflecting wall is incorporated into the simulation scenario to demonstrate the flexibility of the proposed Kalman filte