SBS-suppression in variably strained fibers for fiber-amplifiers and fiber-lasers with a high spectral power density - Engelbrecht, Rainer; Hagen, J; Schmidt, M (XV Int. Symp. on Gas Flow, Chemical Lasers and High-power Lasers, GCL/HPL 2004, Prague. Proceedings of SPIE, 2005)
Stimulated Brillouin-Scattering (SBS) limits the spectral power density of fiber amplifiers and lasers. Theory and measurements of SBS in fibers with a defined strain distribution are presented. SBS threshold was increased by a factor of 2
lhft_intern.bib::engelbrecht04e

Scalable Multi-Level Synchronization Technique of Distributed Multi-RFSoC-Server Systems for 6G - Karle, Christian; Neu, Marc; Nuss, Benjamin; Witte, Lukas; Scheder, André; Waldner, Eva; Shkurtaj, Ema; Harbaum, Tanja; Becker, Jurgen (International System on Chip Conference, 2024)
The new 6th generation (6G) standard promises increased data transmission rates and opens up entirely new application fields, such as joint-communication and sensing (JCAS). Modern high-performance multiple-input multiple-output (MIMO) systems with high bandwidth and channel count allow evaluation and testing of waveforms and algorithms in real-world scenarios. However, commercial off-the-shelf (COTS) MIMO systems are often costly and cannot be scaled to massive MIMO (mMIMO) systems without huge overhead. The ReLoDAQ system, based on combined radio frequency system-on-chip (RFSoC)-server architecture, offers a cost-effective and scalable solution for the development of a modern mMIMO system. However, this system is only scalable in terms of channel count and does not provide scalable synchronization and trigger mechanisms, which are essential for applications like JCAS or radar. In this paper, we present a scalable sample- and data-level synchronization and trigger mechanism to operate a mMIMO system based on the ReLoDAQ structure in a phase coherent manner. To achieve this, we extend the firmware of the RFSoCs with additional trigger and synchronization logic. Furthermore, we developed a scalable clock distribution network to distribute phase coherent clocks in the mMIMO system. Through measurements on an experimental mMIMO system consisting of two RFSoCs and four servers, we demonstrate that our approach enables phase coherent operation across all channels in the mMIMO system based on the cost-efficient and scalable ReLoDAQ architecture.
CRIS-Team Scopus Importer:2024-12-13
Keywords: 6G; clock distribution; mMIMO; RFSoC; synchronization

Schaltungslehre linearer Mikrowellennetze - Brand, Hans (Buch-Veroeffentlichung, 327 Seiten, 108 Abbildg., S. Hirzel-Verlag, Stuttgart, 1970)
lhft_intern.bib::thirty_years_LHFT_1

Schnelle großflächige Dünnschicht-MSM-Photodetektoren für POF-Datenübertragung - Loquai, Sven; Winkler, Florian; Schmauß, Bernhard; Ziemann, Olaf; Hartl, Engelbert; Bunge, Christian Alexander (Photonische Netze - 12. ITG-Fachtagung, 2011)
CRIS-Team Scopus Importer:2020-10-02

Schnelle Großflächige Metall-Halbleiter-Metall Photodetektoren für Bitraten bis zu 40 Gbit/s über 1 mm optische Polymerfasern - Loquai, Sven; Winkler, F.; Wabra, S.; Schmauß, Bernhard; Hartl, E.; Ziemann, O.; Weinert, Benedict; Schunk, N.; Jäger, K.; Weber, N. (Proceedings of the ITG Fachtagung Photonische Netze, 2013)
UnivIS-Import:2015-04-16:Pub.2013.tech.IE.LEH.schnel

Schnelle großflächige Metall-Halbleiter-Metall Photodetektoren für Bitraten bis zu 40 Gbit/s über Ø 1 mm optische Polymerfasern - Loquai, Sven; Winkler, Florian; Wabra, Stefan; Schmauß, Bernhard; Hartl, Engelbert; Ziemann, Olaf; Weinert, Berndt; Schunk, Nikolaus; Jäger, Klaus; Weber, Norbert (Photonische Netze - 14. ITG-Fachtagung, 2013)
CRIS-Team Scopus Importer:2020-10-02

Schottky-Dioden-Mischer im Sub-Millimeter-Wellenlängenbereich für bildgebende Anwendungen - Schür, Jan (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2013)
UnivIS-Import:2016-07-26:Pub.2013.tech.IE.LEH.schott

Schottky-Structures for THz-Applications based on Quasi-Vertical Design-Concept - Cojocari, O.; Sydlo, C.; Hartnagel, H.; Biber, Stephan; Schür, Jan; Schmidt, Lorenz-Peter (16th International Symposium on space Terahertz Technology ISSTT 2005, Göteborg, Sweden, May, 2005)
UnivIS-Import:2015-04-16:Pub.2005.tech.IE.LEH.schott

Secondary Radar Beacons for Local Ad-Hoc Autonomous Robot Localization Systems - Schütz, Martin; Pavlenko, Tatiana; Vossiek, Martin (Sensors, 2019)
In this paper, we present a detailed analysis and implementation of secondary radar beacons designed for a local ad-hoc localization and landing system (LAOLa) to support the navigation of autonomous ground and aerial vehicles. We discuss a switched linear feedback network as a virtually coherent oscillator and show how to use it as a secondary radar transponder. Further, we present a signal model for the beat signal of the transponder response in an FMCW radar system, which is more detailed than in previously published papers. An actual transponder realization in the 24 GHz ISM band is presented. Its RF performance was evaluated both in the laboratory and in the field. Finally, we put forward some ideas on how to overcome the range measurement inaccuracy inherent in this transponder concept.
CRIS-Team Scopus Importer:2019-12-31
Keywords: autonomous landing; autonomous robot navigation; radar beacons; secondary radar; space exploration; wireless local positioning

Self contained surface acoustic wave temperature sensor. Autarker Oberflächenwellentemperatursensor. - Vossiek, Martin; Schmidt, F. (Frequenz, 2001)
UnivIS-Import:2015-03-09:Pub.2001.tech.IE.LEH.selfco

Self-Interference Leakage Estimation 'N' Cancellation Element: Design of an Active Self-Interference Cancellation Coupler - Fenske, Patrick; Scheder, André; Kögel, Tobias; Root, Konstantin; Vossiek, Martin; Carlowitz, Christian (IEEE Microwave Magazine, 2023)
Monostatic radar systems as well as radars with separated but nearby-placed transmit and receive antennas are beneficial in terms of cost-efficiency and miniaturization, which is necessary for their integration into compact radar systems or mobile devices [1], [2] as well as for radar networks that demand reciprocal transmission channels between the nodes [3]. However, this lack of separation between the transmit (Tx) and receive (Rx) paths due to miniaturization implies only week isolation between Tx and Rx.
CRIS-Team Scopus Importer:2023-06-02

Self-Organizing 3D Wireless Local Positioning Networks for Robot Swarms - Dobrev, Yassen; Reustle, Christoph; Vossiek, Martin (IEEE MTT-S International Microwave Symposium 2016 (IMS 2016), 2016)
lhft_intern.bib::Dobrev2016c

Semantic Segmentation-Based Occupancy Grid Map Learning With Automotive Radar Raw Data - Jin, Yi; Hoffmann, Marcel; Deligiannis, Anastasios; Fuentes-Michel, Juan Carlos; Vossiek, Martin (IEEE Transactions on Intelligent Vehicles, 2023)
Precise road scene understanding is of great essence to autonomous driving. As a widely used method for road scene understanding, occupancy grid mapping is leveraged to detect obstacles and predict drivable road areas. Because of its robustness under harsh conditions, low cost, and large perceptual range, radar sensor is becoming increasingly important to achieve various critical perception tasks. However, for radar-based occupancy grid mapping, current inverse sensor model ISM relies on detection data and is most hand-crafted. In this work, we propose a novel data-driven ISM that employs the range- Doppler matrix as the input. With a systematic evaluation and comparison of our model with classic, hand-crafted ISM and the data-driven, detection-based Occupancy Net using RADIal dataset, we find that data-driven models are far superior to their hand-crafted counterpart. Furthermore, although both data-driven models are on par within near range ( < 50 m ), our model outperforms Occupancy Net by a large margin in far range ( [50 m,100 m] ). Specifically, our model has about a 0.3 and 0.4 improvement in distant range for the intersection over union IoU and F_1 score, respectively. In addition, leveraging adjacent occupancy grid map prediction, we propose a radar-based occupancy flow to precisely distinguish moving objects.
CRIS-Team Scopus Importer:2023-11-03
Keywords: Automotive radar; Data models; deep learning; Estimation; inverse sensor model; occupancy grid map; Radar; Radar detection; Radar measurements; Radar signal processing; road segmentation; Roads; transformer

Semantic Segmentation on 3D Occupancy Grids for Automotive Radar - Prophet, Robert; Deligiannis, Anastasios; Fuentes-Michel, Juan-Carlos; Weber, Ingo; Vossiek, Martin (IEEE Access, 2020)
Radar sensors have great advantages over other sensors in estimating the motion states of moving objects, because they detect velocity components within one measurement cycle. Moreover, numerous successes have already been achieved regarding the classification of such objects. However, the advantage of instantaneous velocity measurement is lost when detecting static objects, so that their classification is much more demanding. In this paper, we use semantic segmentation networks to distinguish between frequently occurring infrastructure objects. The resulting semantic grids provide a location-based classification of the vehicle environment. Since even modern radars have a significantly poorer angular resolution than lidars, the relatively thin radar point cloud is accumulated in advance and transformed into 2D or 3D grids that act as network inputs. Occupancy grids are particularly advantageous here, since they calculate not only the obstacles but also the free spaces. With suitable parameter selection, which is very challenging due to the complexity of radar measurement, the resulting grids allow for good association with camera images. Finally, in order to evaluate possible advantages of 3D grids as network input with respect to the segmentation result, we created and evaluated a simulation dataset and two different real-world datasets in car parks and on motorways. As a result, Jaccard coefficients between 81% and 88% were achieved, depending on the dataset. It was also found that 3D input images lead to improvements in the car park datase

Semantic Segmentation on Automotive Radar Maps - Prophet, Robert; Li, Gang; Sturm, Christian; Vossiek, Martin (IEEE Intelligent Vehicles Symposium, 2019)
As radar sensors can measure an object's range and velocity with a high degree of precision, moving objects can be successfully classified, as well. Classifying stationary objects still needs a lot of research, however. In this paper, we use popular semantic segmentation networks in order to classify the vehicle's immediate infrastructure. To this end, a full 3D measurement is performed with a test vehicle equipped with four high resolution corner radar sensors. A preprocessed point cloud is transformed into various radar maps for input to a neural network. Simulations as well as real-world measurements show an overall intersection over union of 84 and 77%, respectively, as well as an overall accuracy of 95 and 90%, respectively, being a new benchmark for this young research fiel

Sensitive Simultaneous Detection of CO and CO_2 with Commercial DFB Diode Lasers - Engelbrecht, Rainer; Brand, Hans; Schmidt, Lorenz-Peter (Proceedings, IRS2 (6. Conf. On Infrared Sensors and Systems, Erfurt 2000), 2000)
UnivIS-Import:2015-04-16:Pub.2000.tech.IE.LEH.sensit

Sensitive Simultaneous Detection of CO and CO_2 with Commercial DFB Diode Lasers for Optical Communication Systems - Engelbrecht, Rainer; Brand, Hans; Schmidt, Lorenz-Peter (2000)
lhft_intern.bib::thirty_years_LHFT_437

Sensor-assessed grasping time as a biomarker of functional impairment in rheumatoid arthritis - Coppers, Birte; Heinrich, Simon; Tascilar, Koray; Phutane, Uday; Kleyer, Arnd; Simon, David; Bräunig, Johanna; Penner, Johann; Vossiek, Martin; Schönau, Verena; Bayat, Sara; Schett, Georg; et al. (Scientific Reports, 2025)
Quantifying physical impairment in rheumatoid arthritis (RA) is important to determine disease burden and disability. Therefore, we aimed to define hand function impairments in RA patients using an opto-electronic measurement system (OMS). In this cross-sectional pilot study, spatio-temporal and hand segment data were collected during the fine motor skill Moberg Picking-Up Test (MPUT) and two elementary hand movement tasks in RA patients and healthy controls (HC) using a marker-based OMS. The duration of two MPUT movement phases (grasping, transporting 12 objects) and kinematic characteristics during the elementary movements were evaluated. We analyzed between-group differences using linear mixed-effects models accounting for within-participant clustering of hands and adjusting for age and sex. Measurements were obtained from 24 RA and 23 HC. The mean duration of the grasping phase of MPUT was longer in RA patients compared to HC while transporting times were identical, showing a significant group-phase interaction (p < 0.001). Interphalangeal joint angle ratios were similar in RA and HC (p > 0.05) with a lower ratio in both groups for the task thumb-finger opposition compared to flexion of joints. In RA patients especially grasping objects was impaired, and performance time for a subset of objects may serve as a quantitative biomarker of functional impairment.<br
CRIS-Team Scopus Importer:2025-03-14
Keywords: Biomarkers; Biomechanics; Fine-motor skills; Hand; Rheumatoid arthritis

Sensortechnik: Handbuch fuer Praxis und Wissenschaft - Vossiek, Martin; Mágori, V (Sensortechnik: Handbuch fuer Praxis und Wissenschaft, 2014)
lhft_intern.bib::Vossiek2015

ShaRPy: Shape Reconstruction and Hand Pose Estimation from RGB-D with Uncertainty - Wirth, Vanessa; Liphardt, Anna-Maria; Coppers, Birte; Bräunig, Johanna; Heinrich, Simon; Leyendecker, Sigrid; Kleyer, Arnd; Schett, Georg; Vossiek, Martin; Egger, Bernhard; Stamminger, Marc (Proceedings of the IEEE/CVF International Conference on Computer Vision (ICCV) Workshops, 2023)
Despite their potential, markerless hand tracking technologies are not yet applied in practice to the diagnosis or monitoring of the activity in inflammatory musculoskeletal diseases. One reason is that the focus of most methods lies in the reconstruction of coarse, plausible poses, whereas in the clinical context, accurate, interpretable, and reliable results are required. Therefore, we propose ShaRPy, the first RGB-D Shape Reconstruction and hand Pose tracking system, which provides uncertainty estimates of the computed pose, e.g., when a finger is hidden or its estimate is inconsistent with the observations in the input, to guide clinical decision-making. Besides pose, ShaRPy approximates a personalized hand shape, promoting a more realistic and intuitive understanding of its digital twin. Our method requires only a light-weight setup with a single consumer-level RGB-D camera yet it is able to distinguish similar poses with only small joint angle deviations in a metrically accurate space. This is achieved by combining a data-driven dense correspondence predictor with traditional energy minimization. To bridge the gap between interactive visualization and biomedical simulation we leverage a parametric hand model in which we incorporate biomedical constraints and optimize for both, its pose and hand shape parameters. We evaluate ShaRPy on a keypoint detection benchmark and show qualitative results of hand function assessments for activity monitoring of musculoskeletal diseases.
Keywords: Musculoskeletal diseases; Hand Pose and Shape Estimation; Uncertainty Estimation; Hand Tracking

Short 17-cm DBR Raman Fiber Laser With a Narrow Spectrum - Siekiera, Alexander; Engelbrecht, Rainer; Nothofer, Andreas; Schmauß, Bernhard (IEEE Photonics Technology Letters, 2012)
We present experimental results on the lasing of a short distributed Bragg reflector (DBR) Raman fiber laser (RFL) with short cavity length. The high finesse laser cavity with an effective length of 17 cm was realized by direct inscription of two Bragg gratings into a short piece of highly nonlinear polarization maintaining Raman fiber. It is pumped by an Ytterbium fiber laser at 1100 nm with up to 8 W pump power. The Stokes wave at 1151 nm is generated within the DBR RFL with 700-mW output power and a narrow spectral full-width at half-maximum bandwidth of 60 pm. Due to the short cavity length, the number of oscillating longitudinal modes is strongly reduced to less than 24 modes. The short DBR RFL has a low lasing threshold of 4.1 W. Its spectral properties and temporal stability are investigated. Distinct longitudinal cavity modes could be observed within the radio-frequency intermode-beat spectrum detected with a fast photodiode. The measured mode separation of 607 MHz validates the short effective length of 17 c
lhft_intern.bib::Siekiera2012a

Short Raman Fiber Laser and Raman-MOPA with Narrow Spectral Bandwidth - Siekiera, Alexander; Engelbrecht, Rainer; Nothofer, Andreas; Schmauß, Bernhard (SAOT International Workshop on Fiber Lasers, Sensors and Materials, 2011)
lhft_intern.bib::Siekiera11

Short Range Imaging Radiometry at 600 GHz - Rehm, G; Guckenberger, K; Huber, K; Brand, Hans (1997)
lhft_intern.bib::thirty_years_LHFT_410

Short Range Imaging with Optimized Sparse Array - Gumbmann, Frank; Schmidt, Lorenz-Peter (EuSAR, Aachen, 7.06.-10.6., 2010)
This paper presents a MIMO imaging system on the basis of a hybrid concept with synthetic aperture radar (SAR) and digital beam forming (DBF). By moving a multistatic linear array perpendicular to the array dimension a two dimensional aperture is sampled. The scope of application is the field of non destructive testing (NDT) and security systems. Thus the frequency range 75-90 GHz seems to be a good compromise between lateral resolution and penetration depth. A moderate number of transmit and receive channels is achieved by a sparse periodic array (SPA) design. Since this is a far field approach, ambiguities are not well suppressed in the near field point spread function of the sparse array. Therefore an optimized array was developed as well as a post processing algorithm on the basis of a notch filter. This notch filter is applied to attenuate the main part of the ambiguous energy in the doppler spectrum. Results are demonstrated with simulated and measured data.
lhft_intern.bib::Gumbmann10b

Signal Integrity: From Signal Path Analysis to Application Performance Prediction - Helmreich, Klaus (Tutorial TMB Demystifying Microwave Signal Integrity - High Speed Design & Measurement, 2008)
UnivIS-Import:2015-04-16:Pub.2008.tech.IE.c3scha.signal

Signal Processing for Commercial Radar Sensors - Vossiek, Martin; Gulden, Peter; Christmann, Mark (3rd Int. Workshop on Commercial Radio Sensors and Communication Techniques, 2001)
UnivIS-Import:2015-04-16:Pub.2001.tech.IE.LEH.signal

Signal processing methods for millimetrewave FMCW radar with high distance and Doppler resolution - Vossiek, Martin; von Kerssenbrock, T.; Heide, Patric (27th European Microwave Conference and Exhibition. Bridging the Gap Between Industry and Academia., 1997)
Novel FMCW radar concepts for precise distance and velocity measurement are presented. The systems incorporate a SAW reference delay line used to measure the instantaneous phase of the oscillator signal. The algorithms evaluate the specific effects of Doppler frequency shifts in the presence of phase errors such as oscillator phase noise or a nonlinear FM modulation. A method that combines a sweep linearisation with a predistorted modulation signal and a constant phase interval sampling technique are presented. ARMA-modeling for high resolution spectral estimation is applied in order to obtain high Doppler and distance resolution at a moderate sweep bandwidth. Furthermore, a nonlinear FM approach is shown that particularly uses phase error effects to determine the object speed. Using this technique the optimal FMCW radar distance resolution at a given sweep bandwidth is obtained independently of the Doppler resolution. The functionality of the concepts is demonstrated at millimetrewave frequencies. The paper illustrates, that the combination of advanced signal processing schemes with a cost-effective front-end can provide high performance microwave sensors.
UnivIS-Import:2015-04-16:Pub.1997.tech.IE.LEH.signal

Signal propagation properties of anisotropic conducting polymers up to 110 GHz and their applicability in test fixtures - Sippel, Mark; Gold, Gerald; Helmreich, Klaus (20th IEEE Workshop on Signal and Power Integrity, SPI 2016, 2016)
Over the past decades data rates and hence frequencies rose continuously. Extrapolating this trend into the future leads to challenges with temporary microwave interconnects used in test adapters. Existing test socket concepts are going to reach their applicability limit. Most promising candidates to meet the requirements of the emerging challenges in microwave device interfacing are thin, anisotropic conducting polymers. This paper focuses on newly developed measurement methods for evaluating the microwave characteristics of anisotropic conducting polymers up to 110 GHz.

Silicon-Micromachining and Electrical Characterization of a 600 GHz Schottky-Diode Mixer with Integrated Octagonal Horn Antenna - Biber, Stephan; Schür, Jan; Cojocari, O.; Hartnagel, H.; Schmidt, Lorenz-Peter (4th ESA Workshop on Millimetre Wave Technology and Applications, Helsinki, Finnland, February, 2006)
UnivIS-Import:2015-04-16:Pub.2006.tech.IE.LEH.silico

Silicon Photonics Wavelength-Independent C-Band Tunable Optical Filter With Feasible Thermal Tuning Requirements - Alnairat, Saif; Wohlfeil, Benjamin; Djordjevic, Stevan; Schmauß, Bernhard (2022 EUROPEAN CONFERENCE ON OPTICAL COMMUNICATION (ECOC), 2022)
CRIS-Team WoS Importer:2023-03-31

Simple Approach for brief RF Characterization of thin 3D printable Dielectrics - Sippel, Mark; Lomakin, Konstantin; Gold, Gerald; Reitberger, Thomas; Neermann, Simone; Helmreich, Klaus (21st IEEE Workshop on Signal and Power Integrity (SPI 2017), 2017)

Simple automatic nonlinear compensation with low complexity for implementation in coherent receivers - Geyer, J. C.; Fludger, C. R. S.; Duthel, T.; Schulien, C.; Schmauß, Bernhard (ECOC, 2010, 36th European Conference and Exhibition, 2010)
lhft_intern.bib::Geyer10b

Simulation and Measurement of Dielectric Antennas at 150 GHz - Weinzierl, Jochen; Richter, Jürgen; Rehm, Guenther; Brand, Hans (Proceedings of the 29th European Microwave Week, 1999)
Based on the development of a flexible, dielectric waveguide system for frequencies in the region of 150 GHz [1], the antenna characteristics of various tapered ends of dielectric waveguides have been studied. The flexible waveguide consists of a rectangular, dielectric fibre made of polyethylene. The paper describes the simulation and optimization of different tapers using 3D electromagnetic field computation, the precise fabrication of the antennas and the verification of the simulated data by field measurements at 150 GHz. © 1999 IEEE.
UnivIS-Import:2015-04-16:Pub.1999.tech.IE.LEH.simula

Simulation and Measurement of Dielectric Antennas at 150 GHz - Weinzierl, Jochen; Richter, J; Rehm, G; Brand, Hans (IEEE, 1999)
Based on the development of a flexible, dielectric waveguide system for frequencies in the region of 150 GHz [1], the antenna characteristics of various tapered ends of dielectric waveguides have been studied. The flexible waveguide consists of a rectangular, dielectric fibre made of polyethylene. The paper describes the simulation and optimization of different tapers using 3D electromagnetic field computation, the precise fabrication of the antennas and the verification of the simulated data by field measurements at 150 GH
lhft_intern.bib::thirty_years_LHFT_434

Simulation and Measurement of Interconnect Structures for High Speed Digital Systems - Nisznansky, Martin; Ziegler, Christof; Martius, Siegfried; Schmidt, Lorenz-Peter; Müller, J. (Signal Propagation on Interconnects, 2002)
Results of electromagnetic simulations and measurements of simple interconnect structure are discussed in this paper. The presented structure was realised on LTCC multilayer board which are suitable for manufacturing of multichip modules for next generation communication systems with clock rates in the 10-100GHz range. From the presented results it is possible to obtain an impression about distortion of high speed digital signals after passing this or similar interconnect structures. Precision microwave measurement techniques that are important for verification of such simulations are discussed, too. © 2002 IEEE.
UnivIS-Import:2015-04-16:Pub.2002.tech.IE.LEH.simula

Simulation Assisted Characterization of Attenuation at Microstrip Transmission Lines fabricated by Laser Direct Structuring - Wang, Li; Lomakin, Konstantin; Job, Alexander; Süß-Wolf, Robert; Gold, Gerald; Franke, Jörg (2021 14th International Congress: Molded Interconnect Devices, MID 2021 - Proceedings, 2021)
This paper aims to provide a design approach to predict the attenuation of microstrip transmission lines fabricated by Laser Direct Structuring (LDS) on LDS polymer substrates. The impact of conductor and dielectric losses are separately considered in full wave simulation to evaluate the order of corresponding contribution to the total attenuation. Impact of surface roughness on signal propagation is taken into account by the Gradient Model. Simulations are compared with measurements of fabricated microstrip lines. The result also gives an estimation on the applicability of the LDS process towards radio frequency components.
CRIS-Team Scopus Importer:2021-04-02
Keywords: component; formatting; insert (key words); style; styling

Simulation-based comparison of noise effects in wavelength modulation spectroscopy and direct absorption TDLAS - Lins, Bastian; Zinn, P.; Engelbrecht, Rainer; Schmauß, Bernhard (Applied Physics B-Lasers and Optics, 2010)
A simulative investigation of noise effects in wavelength modulation spectroscopy (WMS) and direct absorption diode laser absorption spectroscopy is presented. Special attention is paid to the impact of quantization noise of the analog-to-digital conversion (ADC) of the photodetector signal in the two detection schemes with the goal of estimating the necessary ADC resolution for each technique. With laser relative intensity noise (RIN), photodetector shot noise and thermal amplifier noise included, the strategies used for noise reduction in direct and wavelength modulation spectroscopy are compared by simulating two respective systems. Results show that because of the combined effects of dithering by RIN and signal averaging, the resolutions required for the direct absorption setup are only slightly higher than for the WMS setup. Only for small contributions of RIN an increase in resolution will significantly improve signal quality in the direct scheme. © Springer-Verlag 2010.
UnivIS-Import:2015-03-09:Pub.2010.tech.IE.LEH.simula

Simulation eines faserbasierten SPM-2R-Regenerators - Striegler, Arne; Wietfeld, André; Schmauß, Bernhard (ITG Workshop Modellierung photonischer Komponenten und Systeme, Berlin, April, 2003)
UnivIS-Import:2015-04-16:Pub.2003.tech.IE.LEH.simula

Simulation of the High Speed Data Transmission POF System - Schmauß, Bernhard; Kruglov, R.; Loquai, Sven; Ziemann, O.; Poisel, H.; Vinogradov, J.; Zadorin, A.; Surkova, G. (15. ITG-Fachtagung in Köln, Kommunkationskabelnetze, 2008)
UnivIS-Import:2015-04-16:Pub.2008.tech.IE.LEH.simula

Simulation von Faser-Bragg-Gittern in mehrmodigen Fasern - Werzinger, Stefan; Schmauß, Bernhard; Engelbrecht, Rainer (Workshop der ITG-Fachgruppe 5.3.1. (Modellierung photonischer Komponenten und Systeme), 2015)
lhft_intern.bib::Werzinger2015

Simulation von ortsverteilten und diskreten faseroptischen Sensor-Elementen - Werzinger, Stefan; Köppel, Max; Engelbrecht, Rainer; Schmauß, Bernhard (Workshop der ITG-Fachgruppe 5.3.1 (Modellierung photonischer Komponenten und Systeme), 2016)
lhft_intern.bib::Werzinger2016a

Simulative Optimierung eines 160 Gbit/s Übertragungssystems - Wietfeld, André; Striegler, Arne; Schmauß, Bernhard (ITG Workshop Modellierung photonischer Komponenten und Systeme, Berlin, April, 2003)
UnivIS-Import:2015-04-16:Pub.2003.tech.IE.LEH.simula_0

Simulative Untersuchung einer 160 Gbit/s Übertragungsstrecke mit einem ODTM Empfänger - Wietfeld, André; Hofmann, A.; Striegler, Arne; Schmauß, Bernhard (Conf. Proc., 3. ITG Fachtagung Photonische Netze, ITG Fachbericht 172, 2002)
UnivIS-Import:2015-04-16:Pub.2002.tech.IE.LEH.simula_2

Simultaneous 2D strain sensing using polymer planar Bragg gratings. - Rosenberger, Manuel; Eisenbeil, Waltraud; Schmauß, Bernhard; Hellmann, Ralf (Sensors, 2015)
We demonstrate the application of polymer planar Bragg gratings for multi-axial strain sensing and particularly highlight simultaneous 2D strain measurement. A polymer planar Bragg grating (PPBG) fabricated with a single writing step in bulk polymethylmethacrylate is used for measuring both tensile and compressive strain at various angles. It is shown that the sensitivity of the PPBG strongly depends on the angle between the optical waveguide into which the grating is inscribed and the direction along which the mechanical load is applied. Additionally, a 2D PPBG fabricated by writing two Bragg gratings angularly displaced from each other into a single polymer platelet is bonded to a stainless steel plate. The two reflected wavelengths exhibit different sensitivities while tested toward tensile and compressive strain. These characteristics make 2D PPBG suitable for measuring multi-axial tensile and compressive strain.

Simultaneous measurement of ^12CO_2, ^13CO_2 and ^12C^18O^16O with a NIR fiber-coupled DFB diode-laser spectrometer - Lau, S.; Engelbrecht, Rainer; Sallfner, K.; Löhmannsröben, Hans-Gerd (Conference on Tunable Diode Laser Spectroscopy TDLS-2005, Florenz, July, 2005)
UnivIS-Import:2015-04-16:Pub.2005.tech.IE.LEH.simult

Simultaneous Sensing of Temperature and Strain by Combined FBG and Mode-Interference Sensors - Siekiera, Alexander; Engelbrecht, Rainer; Buethe, L.; Schmauß, Bernhard (Bragg Gratings, Photosensitivity, and Poling in Glass Waveguides (BGPP) 2012, 2012)
We examine the combination of a FBG and mode-interference sensor for simultaneous temperature and strain sensing. Results for temperature and strain sensitivities are presented and the sensor performance in a simultaneous measurement experiment is evaluated.
lhft_intern.bib::Siekiera2012b

Simultaneous Temperature Estimation of Multiple Gratings Using a Multi-Layer Neural Network - Djurhuus, Martin; Schmauß, Bernhard; Clausen, Anders T.; Zibar, Darko (IEEE Photonics Technology Letters, 2020)
This paper introduces a method to do simultaneous temperature estimations of multiple gratings in an FBG array. The method involves training a multi-layer neural network using simulated training data. The network is then used to estimate the temperature changes of multiple gratings simultaneously using only the experimentally obtained spectrum of the FBG array. The versatility of the method is seen from the results of three different setups. That is the broadband lightsource with OSA, the broadband lightsource with spectrometer, and incoherent optical frequency domain reflectometry. The method can estimate the temperature changes with high accuracy and low root mean squared error (RMSE) for the setups under consideration. Finally, the method is shown to be capable of simultaneous estimation of temperature changes for 19 FBGs using the BLS setup with a maximum absolute error of 6.64 K and an RMSE of 1.69 K in only 1.74 ms/FBG.
CRIS-Team WoS Importer:2020-12-18

Single-channel distributed Raman temperature sensing based on a 1-dimensional convolutional neural network - Renner, Esther; Mampilli, John Sebert; Amer, Nadia; Schmauß, Bernhard (Optical Fiber Technology, 2024)
We present a simple and cost-efficient single-channel Raman distributed temperature sensing (DTS) system based on temperature prediction by a 1-dimensional convolutional neural network (1D-CNN) from the Raman anti-Stokes backscatter trace. The proposed Raman DTS system is based on incoherent optical frequency domain reflectometry with homodyne down-conversion with excitation of spontaneous Raman backscattering by an L-band laser diode and detection of the Raman anti-Stokes in the optical C-band. A 1D-CNN is employed to predict the spatially resolved temperature profile along the fiber from the obtained anti-Stokes backscatter trace only and thus, solves the problem of temperature referencing for single-channel Raman DTS systems. The network was trained on three different scenarios, consisting of uniform and non-uniform temperature profiles along the fiber in a temperature range from 0 °C to 60 °C. The obtained results show that the measurement and signal processing pipeline presented here is capable of predicting the temperature distribution to an accuracy of approximately 1 K in the tested scenarios.
CRIS-Team Scopus Importer:2024-10-25
Keywords: Convolutional neural network; Incoherent optical frequency domain reflectometry; Optical fiber sensing; Raman distributed temperature sensing

Single-Fed Additively Manufactured Conical Horn Antenna with Circular Polarization for Millimeter-Wave Applications - Dorbath, Benedikt; Lomakin, Konstantin; Pfahler, Tim; Schür, Jan; Vossiek, Martin (2023 17th European Conference on Antennas and Propagation (EuCAP), 2023)
In this paper, we present a circularly polarized conical horn antenna fed by a standard WR19 waveguide. The antenna was additively manufactured from polymer resin by digital light processing and subsequently electroplated with a thin copper surface finish, which enables the guidance of electromagnetic waves and thus the functionality of the antenna. Both processes are cost effective and time efficient compared to the traditional split-block technique. The performance of the fabricated conical horn antenna is specified by a measured realized gain of 11 − 13.5 dBi over the entire frequency band of interest from 40 − 50 GHz for circular polarization. This is in high agreement with the simulated gain of 11.3 − 14.2 dBi. The measured reflection coefficient for this frequency range is less than −16.5 dB while the axial ratio remains below 3 dB. In simulation, an axial ratio of less than 5 dB is reached over the entire Q Band from 40 − 60 GHz. Furthermore, this circularly polarized antenna design, in combination with the flexibility of additive manufacturing and electroplating, can be integrated conveniently with other components and can satisfy various demands for the gain and main lobe width, as well as both left-hand or right-hand circular polarization by slight changes to its geometry.<br

Size-Reduction and Suppression of Cavity-Resonances in Hybrid mm-Wave Antennas for Polarimetric Measurements - Methfessel, Sebastian Dirk; Schmidt, Lorenz-Peter (43th European Microwave Week, 2013)
Size and feed structure are some of the important constraints for using antenna-elements in multi-element two-dimensional arrays, where easy planar integration with transceiver chips is essential. This applies especially when differential signaling and adaptable polarization is required. Based on a balanced-fed patch-excited cavity-backed horn antenna (hybrid antenna), feeding concepts and approaches to reduce size are discussed and evaluated in this paper. The influence of the substrate integrated cavity is analyzed and methods to overcome the restrictions are presented, together with simulated and measured results. The optimized antennas achieve a relative bandwidth of more than 17% for 10 dB return loss, a gain of more than 5 dBi as well as symmetric and homogeneous radiation patterns in amplitude and phase with low cross-polarization. © 2013 European Microwave Association.
UnivIS-Import:2015-04-16:Pub.2013.tech.IE.LEH.sizere
Keywords: Antenna arrays; Antenna feeds; Aperture coupled antennas; Cavity resonators; Horn antennas; Millimeter wave radar; Radar imaging; Radar polarimetry

Size-reduction and suppression of cavity-resonances in hybrid mm-wave antennas for polarimetric measurements - Methfessel, Sebastian Dirk; Schmidt, Lorenz-Peter (43rd European Microwave Conference, 2014)
Size and feed structure are some of the important constraints for using antenna-elements in multi-element two-dimensional arrays, where easy planar integration and appropriate matching with transceiver chips are essential. This applies especially when differential signaling and adaptable polarization are required. Based on a balanced-fed patch-excited cavity-backed horn antenna (hybrid antenna), feeding concepts, and approaches to reduce size are discussed and evaluated in this paper. The influence of the substrate-integrated cavity is analyzed and methods to overcome the restrictions are presented, together with simulated and measured results. The antenna elements are evaluated with regard to their use in multistatic and polarimetric sparse arrays, which will be briefly introduced. The optimized antennas achieve 10 dB return loss, a gain of more than 5 dBi as well as symmetric and homogeneous radiation patterns in amplitude and phase with low cross-polarization in the desired frequency-band of operation between 70 and 80 GH
lhft_intern.bib::Methfessel2013n

SLA Printed 3D Waveguide Paths for E-Band using Electroless Silver Plating - Lomakin, Konstantin; Herold, Sophie; Ringel, Lorenz; Ringel, Johannes; Simon, D.; Sippel, Mark; Sion, A.; Vossiek, Martin; Helmreich, Klaus; Gold, Gerald (IEEE Transactions on Components, Packaging and Manufacturing Technology, 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 tech- niques 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 distri- bution and feeding networks in the context of rapid prototyping, automotive and space related applications

SLA Printed Sub-Terahertz Bifilar Helix Antenna for Radar Imaging - Panusch, David; Bachbauer, Felix; Lomakin, Konstantin; Gold, Gerald (Kleinheubacher Tagung 2023, 2023)
The continuous improvement of additive stereo-lithographic manufacturing (SLA) allows to fabricate filigree sub-Terahertz antennas. This paper presents the first 3D-printed bifilar WR6 helix antenna, which depends on recent developments of printed transition from waveguides to bifilar helices. The measurements of the circularly polarized antenna indicate a −15 dB bandwidth of B15 dB = 10GHz. The axial ratio AR is within B15 dB <3.5dB in the main lobe direction. The achieved linear polarization gain is Glp 14dBi with a circular polarization gain of Gcp 11 to 12 dBi. Due to its small form factor and circular polarization the proposed bifilar helical antenna is suitable for applications in the 120 GHz ISM band, i.e. polarimetric imaging and decomposition as well as broadband communication, e.g. 6G applications.<br
Keywords: Antenna measurements; Waveguide transitions; Polarization; Helical antennas; Imaging; Radar imaging; Radar antennas

Slip-Reduced Carrier Phase Estimation for Coherent Transmission in the Presence of Non-Linear Phase Noise - Bisplinghoff, Andreas; Vogel, C.; Kupfer, T.; Langenbach, S.; Schmauß, Bernhard (Proceedings of the Optical Fiber Communication Conference (OFC), 2013)
Pilot-free coherent systems use blind carrier phase estimation (CPE) methods that inevitably generate cycle slips. We propose an enhanced CPE reducing the cycle slip probability low enough to enable turbo differential decoding. © 2013 OS
UnivIS-Import:2015-04-16:Pub.2013.tech.IE.LEH.slipre

SLS-Printed E-Band Waveguides and the Impact of Surface Roughness - Hofmann, Andreas; Lomakin, Konstantin; Kleinlein, Micha; Bader, Tobias; Sippel, Mark; Gold, Gerald (European Microwave Conference (EuMC), 2023)

Small form factor and low profile quad-band System-in-Package (SiP) module - Shevelov, Mykola; Sieroshtan, Volodymyr; Ruban, Oleksandr; Burygin, Andriy; Komakha, Petro; Aleksieiev, Oleg; Chayka, Oleg; Sevskiy, Georgiy; Stoehr, Peter; Heide, Patric; Vossiek, Martin (IEEE International Microwave Symposium 2011, 2011)
A very small form factor and low profile quad-band System-in-Package (SiP) module based on the state-of-the-art brand new 65nm CMOS IC is presented. The SiP module provides full function of 2.4G and 5G WLAN, Bluetooth, GPS, FM radio and FM transmitter. The highly integrated device incorporates single chip, RF front-end module, filters for dual band WLAN and GPS, number of SMD components and metal case which provides mechanical protection and implements EMI shielding. A laminate substrate provides the interconnection and distribution of the signals and ground to various components and acts as the carrier to support the die and allow the die IOs to be distributed to the package IOs. Very compact SiP solution with dimensions of 9.5×11.9×1.2mm3 forms a complete stand-alone multi functional wireless communication syste
lhft_intern.bib::Shevelov2011

SMMW Lasers with Optical Pump Beam Guiding - Raum, M; Brand, Hans (1998)
lhft_intern.bib::thirty_years_LHFT_418

Soft decision metrics for differentially encoded QPSK - Bisplinghoff, A.; Cabirol, C.; Langenbach, S.; Sauer-Greff, W.; Schmauß, Bernhard (Optical Communication (ECOC), 2011 37th European Conference and Exhibition on, 2011)
lhft_intern.bib::Bisplinghoff2011

Soft-decision turbo decoding for coherent transmission with phase slips - Bisplinghoff, Andreas; Langenbach, S.; Schmauß, Bernhard (Photonische Netze - 13. ITG-Fachtagung, 2012)
We investigate the impact of frequent phase slips on turbo decoding of low density parity check codes combined with differentially encoded QPSK. Iterative joint soft differential demodulation and soft-decision decoding improves the signal to noise ratio performance of coherently demodulated QPSK, but compromises its phase slip resilience.
CRIS-Team Scopus Importer:2021-04-19

Soft-Decision Turbo Decoding for Coherent Transmission with PhaseSlips - Bisplinghoff, Andreas; Langenbach, S.; Schmauß, Bernhard (13th ITG-Fachtagung Photonische Netze, 2012)
lhft_intern.bib::Bisplinghoff2012

Software-switching between direct absorption and wavelength modulation spectroscopy for the investigation of ADC resolution requirements - Lins, Bastian; Engelbrecht, Rainer; Schmauß, Bernhard (Applied Physics B-Lasers and Optics, 2012)
We present a tunable diode laser spectrometer that can be software-switched between a wavelength modulation spectroscopy (WMS) operation mode and the direct absorption spectroscopy (DAS) technique on a per-scan basis. The new setup allows a direct comparison between the two techniques under equal hardware and system environment conditions. In this work, we compare the impact of analog-to-digital converter resolution for operation in WMS and DAS mode. Example concentration evaluations show that in the DAS approach, relative absorptions smaller than the least significant bit can be measured with scan averaging and FIR-filtering applied. With full resolution, both techniques show similar performance in our setup, with a slight advantage for the WMS implementation. © Springer-Verlag 2012.
UnivIS-Import:2015-03-09:Pub.2012.tech.IE.LEH.softwa

Soziale Implikationen von Gesundheitstechnologien in der Palliativversorgung – Entwicklung eines konzeptionellen Rahmenwerks - Öhl, Natalie; Steigleder, Tobias; Hille, Eva Maria; Braun, Markus; Weisser, Alina; Muehlensiepen, Felix; Vossiek, Martin; Eskofier, Björn; Kölpin, Alexander; Forbes, C C; Ostgathe, Christoph; Heckel, Maria (Zeitschrift für Palliativmedizin, 2024)
Hintergrund Neue Gesundheitstechnologien wie beispielsweise Apps, radarbasierte Messtechniken oder Robotik bieten Potentiale zur Unterstützung der Palliativversorgung. Ihr Einsatz führt zu sozialen Auswirkungen in der Versorgungspraxis, die vielschichtig, teils verzögert erkennbar und zu berücksichtigen sind. Da soziale Teilhabe und zwischenmenschliche Begegnungen in der Palliativversorgung zentrale therapeutische Konzepte ausmachen ist hier besondere Vorsicht geboten. Gesundheitstechnologien dürfen die Grundsätze der Palliativversorgung nicht stören oder beeinträchtigen. Um dies sicherzustellen sind die sozialen Auswirkungen von Gesundheitstechnologien bei deren Entwicklung und Nutzung fortlaufend zu analysieren und zu berücksichtigen. Bislang fehlt eine Konzeptionalisierung sozialer Implikationen von Gesundheitstechnologien in der Palliativversorgung. Methode Zur Erforschung sozialer Implikationen von Gesundheitstechnologien in der Palliativversorgung wurde zwischen September 2022 und Juli 2023 ein sequentielles Forschungsdesign mit Methoden der qualitativ-empirischen Sozialforschung angewandt: (1) Zunächst wurden iterative interdisziplinäre Diskussionsrunden durchgeführt und mittels konzeptioneller Mapping-Methode ausgewertet. Darauf aufbauend folgten (2) drei Fokusgruppen mit Forschenden, medizinischem Personal und einer Patient-and-Public-Involvement Gruppe, welche mittels qualitativ strukturierter Inhaltsanalyse ausgewertet wurden. Mit den Ergebnissen wurde ein Rahmenwerk – das CARE-HAUS Rahmenwerk – entwickelt, dessen Anwendbarkeit in zwei Fallstudien (3) beispielhaft anhand von radarbasierten Messtechniken und Wearables zur Bewegungsüberwachung überprüft wurde. Das Forschungsdesign wurde von fortlaufenden iterativen narrativen Literaturrecherchen begleitet. Ergebnisse Das CARE-HAUS Rahmenwerk konzeptualisiert soziale Implikationen von Gesundheitstechnologien in der Palliativversorgung. Es zeigt Bereiche auf, in denen Gesundheitstechnologien förderliche und potenziell hinderliche Auswirkungen auf die Versorgungspraxis haben können, wobei die Grundsätze und Zielsetzungen der Palliativversorgung als Maßstab gelten. Die identifizierten Bereiche umfassen die beteiligten Akteur:innen und ihre Charakteristika, Interaktionen, Rollen, Aufgaben und Prozesse im Versorgungskontext und schließlich gesellschaftliche, strukturelle, organisatorische und fachliche Rahmenbedingungen. Schlussfolgerung Das CARE-HAUS Rahmenwerk bietet eine Orientierung für die Analyse sozialer Implikationen vor und während Technologieentwicklungen und -implementierungen. Künftig muss die Anwendbarkeit des CARE-HAUS Rahmenwerks in weiteren Studien evaluiert werde

Space-Resolved Measurement and 2D-Mapping of Material Parameters Using Multi-Angle Reflection Ellipsometry in W-Band - Cenanovic, Amir; Schmidt, Lorenz-Peter (Proceedings of the International Microwave Symposium 2013, 2013)
In this paper a free-space method is presented for space-resolved measurement of the relative permittivity and thickness of a single layer dielectric material in the W-band. The reflection of parallel and perpendicularly polarized waves from the material under test is measured with a polarimetric linear array. Synthetic aperture focusing of the raw data is performed, in order to obtain space-resolved reflection coefficients, from which the material parameters are determined using the spectroscopic multi-angle reflection ellipsometry technique. Results of the proposed method are presented in the frequency range of 75-95 GHz for low loss materials with a few millimeters of thickness. The relative uncertainty in determining the thickness and ε′ of Teflon is 2% and 3% respectively. The capability of the method to accomplish space resolved material characterization is demonstrated by two dimensional mapping of the relative permittivity of Teflon with a high accuracy. © 2013 IEEE.
UnivIS-Import:2015-04-16:Pub.2013.tech.IE.LEH.spacer
Keywords: Ellipsometry; Permittivity; Radar imaging

Spannungsgesteuerter Colpitts-Oszillator mit weitem Abstimmbereich in Silizium-Germanium-Technologie und Ausgangsschalter zur Generierung gepulster frequenzmodulierter Ultrabreitband-Signale - Eßwein, Alexander; Dehm-Andone, Gunther; Aleksieieva, Anna; Carlowitz, Christian; Fischer, Georg; Vossiek, Martin; Weigel, Robert; Ussmueller, Thomas (12. GMM/ITG-Fachtagung Analog 2011, 2011)
lhft_intern.bib::Esswein2011

Sparse Linear Array Design for a Short Range Imaging Radar - Gumbmann, Frank; Tran, Hue Phat; Schmidt, Lorenz-Peter (EuMW, 28.09-2.10., Rom, 2009)
This paper presents the design of an active short range imaging system in the Ka-band (26.6 - 40 GHz). The sensor is a multistatic linear array which is moved perpendicular to the array dimension for the purpose of 3D imaging. By sequentially switching on the transmitters and simultaneous reception of the scattered field by each receiver, a fast sampling of the 2D aperture plane is achieved. To reduce the number of parallel receive channels, a thinned array on the base of sparse periodic arrays (SPA) was developed. Due to non focussing antenna elements, numerical reconstruction algorithms, for near field conditions, have to be applied for a high lateral resolution. First simulation results verify the imaging quality of this concept and the functionality of the proposed reconstruction algorithm. © 2009 EuMA.
UnivIS-Import:2015-04-16:Pub.2009.tech.IE.LEH.sparse

Sparse MIMO Array for Multi-Angle Reflection Ellipsometry - Cenanovic, Amir; Schmidt, Lorenz-Peter (IEEE International Conference on Wireless Information Technology and Systems 2012, 2012)
The combination of the reflection ellipsometry method with a polarimetric imaging system illustrated in Fig. 1(a) offers a promising approach for robust material characterization of dielectric samples from the phase difference of the (p) and (s) -polarized complex images Rp and Rs [1, 2]. Since the phase difference arg(Rp/Rs) depends on the incidence angle α (Fig. 1(b)), a higher sensitivity and robustness in parameter estimation is achieved from measurements at different angles. © 2012 IEEE.
UnivIS-Import:2015-04-16:Pub.2012.tech.IE.LEH.sparse

SPARS — Simultaneous Phase and Amplitude Regenerative Sampling - Carlowitz, Christian; Vossiek, Martin; Girg, Thomas; Dietz, Marco; Schrotz, Albert-Marcel; Maiwald, Tim; Hagelauer, Amelie Marietta; Weigel, Robert; Ghaleb, Hatem; Carta, Corrado; Ellinger, Frank; Du, Xuan-Quang; et al. (Wireless 100 Gbps And Beyond. Architectures, Approaches and Findings of German Research Foundation (DFG) Priority Programme SPP1655, 2020)

Spatial Filtering and Equalization for SSR Signal Detection in a Multipath Environment - Reck, Christoph; Reuther, M.; Berold, Ulrich; Schmidt, Lorenz-Peter (6th German Microwave Conference, 2011)
Detection of Secondary Surveillance Radar (SSR) signals is highly error prone in scenarios where multipath propagation and transponder interference is involved. The proposed method largely improves this situation by iteratively combining smart antenna and classical equalization approaches. A large dataset of SSR replies, recorded at problematic sites of Frankfurt Airport by a multichannel receiver is used for verification.
lhft_intern.bib::Reck11a

Spatially resolved fiber Bragg grating sensing using wavelength scanning incoherent OFDR - Werzinger, Stefan; Köhler, Aaron; Engelbrecht, Rainer; Schmauß, Bernhard (Optical Fiber Communications (OFC) Conference, 2016)
A spatially resolved interrogation of fiber Bragg grating sensors, using incoherent optical frequency domain reflectometry and wavelength scanning is demonstrated. The method potentially allows a spectrally denser sensor packing and provides centimeter range resolution.
lhft_intern.bib::Werzinger2016b

Spatial Resulution of Millimeter Wave Imaging at 75 - 100 GHz and 600 GHz - Tran, Hue Phat; Gumbmann, Frank; Weinzierl, Jochen; Schmidt, Lorenz-Peter (German Microwave Conference, Karlsruhe, March, 2006)
UnivIS-Import:2015-04-16:Pub.2006.tech.IE.LEH.spatia

Spectral Domain Analysis of Dominant and Higher Order Modes in Fin-Lines - Schmidt, Lorenz-Peter; Itoh, T (IEEE Transactions on Microwave Theory and Techniques, 1980)
The spectral domain analysis is applied to deriving dispersion characteristics of the dominant, higher order modes in the fin-line structures. Numerical results are compared with those by a modified spectral domain technique as well as other dat
lhft_intern.bib::Schmidt80b

Spectrum-efficient real-time OFDM MIMO Radar for moving target detection in medium-range applications - Multerer, Thomas; Vossiek, Martin; Prechtel, Ulrich; Ziegler, Volker (IEEE MTT-S International Conference on Microwaves for Intelligent Mobility (ICMIM 2018), 2018)
This paper presents the first measurement results of a new Orthogonal Frequency Division Multiplexing (OFDM) Multiple Input Multiple Output (MIMO) Radar prototype. It is designed to be operated in a dynamic multi-user environment where the individual sensor's RF bandwidth is very limited. Here, the radar uses only 30 MHz. The targeted applications are in the field of Urban (Air) Mobility (UAM) with a medium-range coverage up to 250 m. Another requirement is to observe a wide field of view in azimuth of about 100 degree with a high resolution in azimuth. This was implemented by using a 2 × 8 MIMO processing. A 20 ms frame based evaluation of the OFDM symbols allows to obtain a very high velocity resolution of below 1 m/s. This paper explains details about the radar system, the waveform and the processing but the main part of the paper focuses on the evaluation of a dynamic measuremen
lhft_intern.bib::Multerer2018a

Spektral schmalbandiger Raman-Faserlaser - Hagen, Johannes; Siekiera, Alexander; Engelbrecht, Rainer; Schmauß, Bernhard (WLT Summerschool Hannover, 28.-30. June, 2006)
UnivIS-Import:2015-04-16:Pub.2006.tech.IE.LEH.spektr

Spezialfasern fuer Faserlaser und Sensoren: Grundlagen und Anwendungsbeispiele - Engelbrecht, Rainer; Siekiera, Alexander (Bayerisches Laserzentrum, Workshop Optische Fasern - Faseroptische Komponenten fuer hohe Leistungen, 2012)
lhft_intern.bib::Engelbrecht2012a

Spezifische Faser-Bragg-Gitter fuer Sensor-Applikationen - Engelbrecht, Rainer; Sikiera, A. (Workshop Optische Fasern - Faseroptische Sensorik, 2010)
lhft_intern.bib::engelbrecht10a

Springer Handbook of Lasers and Optics (2nd Ed.) - Engelbrecht, Rainer; Brand, Hans; Rohlfing, F (Springer Handbook of Lasers and Optics (2nd Ed.), 2012)
lhft_intern.bib::Engelbrecht2012

Springer Handbook of Lasers and Optics - Engelbrecht, Rainer; Brand, Hans (Springer Berlin Heidelberg, 2012)
lhft_intern.bib::engelbrecht07a

Springer Handbook of Lasers and Optics - Engelbrecht, Rainer; Brand, Hans (Springer Handbook of Lasers and Optics, 2007)
UnivIS-Import:2015-04-20:Pub.2007.tech.IE.LEH.spring

Stable Coherent MIMO Transport over Few Mode Fiber Enabled by an Adiabatic Mode Splitter - Buelow, H.; Al-Hashimi, H.; Schmauß, Bernhard (Proc. of the 36th European Conference on Optical Communication, Torino, Italy, September, 2010)
lhft_intern.bib::Buelow10

Standardized Characterisation of Device Power Supplies for Automated Test Generation and Simulation - Glaser, Daniel; Müller, Andreas; Lu, Ping; Uygur, Gürkan; Helmreich, Klaus (Tagungsband, 2010)
UnivIS-Import:2015-04-16:Pub.2010.tech.IE.c3scha.standa_5

Standards-Based Construction of a Virtual Test Environment - Lu, Ping; Helmreich, Klaus (Tagungsband, 2008)
UnivIS-Import:2015-04-16:Pub.2008.tech.IE.c3scha.standa

State Observation Using the Phase and the Beat Frequency of a FMCW Radar for Precise Local Positioning and Line-of-Sight Detection - Max, Stephan; Bohn, Christian; Vossiek, Martin (68th IEEE Vehicular Technology Conference (VTC 2008-Fall), 2008)
The accuracy of an FMCW radar working in a multipath environment is mainly limited by the radar signal bandwidth. Furthermore, the separation and identification of line-of-sight (LOS) and non-line-of-sight (NLOS) signals are important and challenging problems in many radar and local positioning applications. In this article, a method is proposed to overcome these restrictions. A state observer is used for an improved fusion of the FMCW radar beat signal frequency and phase. It is shown that the concepts allow for an accuracy improvement of more than one order of magnitude. In addition, the new approach is able to distinguish between NLOS and LOS measurements. The robustness of the system is improved by the implementation of motion type detection algorithms. Practical experiments illustrate that the new technique is superior to standard FMCW radar location methods. ©2008 IEEE.
UnivIS-Import:2015-04-16:Pub.2008.tech.IE.LEH.stateo
Keywords: Local positioning; Radio navigatio; Secondary radar; State observation

Statistical analysis of intrinsic and extrinsic coupling losses for step-index polymer optical fibers - Werzinger, Stefan; Bunge, Christian-Alexander (Optics Express, 2015)
The intrinsic and extrinsic coupling losses of step-index polymer optical fibers are statistically examined by Monte Carlo simulations. In contrast to most existing models that linearly scale individual losses, a comprehensive analytic coupling loss model is used that also considers the interdependencies between mismatches in numerical aperture and core diameter, as well as radial and longitudinal offsets. As a typical example, the coupling losses of A4a.2 step-index multimode fibers are analyzed for an equilibrium mode distribution. The results show considerably less conservative coupling loss estimations than with traditional models, improving link power budgetin
lhft_intern.bib::Werzinger2015b

Statistical assessment of influencing effects on connector losses: A proposal for more balanced tolerances - Bunge, Christian-Alexander; Werzinger, Stefan (24th International Conference on Plastic Optical Fibers, 2015)
lhft_intern.bib::Werzinger2015c

Steady Delivery: Wireless Local Positioning Systems for Tracking and Autonomous Navigation of Transport Vehicles and Mobile Robots - Dobrev, Yassen; Vossiek, Martin; Christmann, Mark; Bilous, Igor; Gulden, Peter (IEEE Microwave Magazine, 2017)
For many players in the service and manufacturing sectors, the cost associated with transportation processes is a key factor in competitiveness and market success. Innovations such as wireless connectivity, RF identification (RFID), and the Internet of Things have already transformed these industries, and this trend-stimulated by modern wireless technologies, wave-based imaging systems, and autonomous driving-is set to continu

Step-size selection for split-step based nonlinear compensation with coherent detection in 112-Gb/s 16-QAM transmission - Lin, Chien-Yu; Asif, Rameez; Hohmannspoetter, Michael; Schmauß, Bernhard (Chinese Optics Letters, 2012)
Non-uniform step-size distribution is implemented for split-step based nonlinear compensation in single-channel 112-Gb/s 16 quadrature amplitude modulation (QAM) transmission. Numerical simulations of the system including a 20 × 80 km uncompensated link are performed using logarithmic step size distribution to compensate signal distortions. 50% of reduction in number of steps with respect to using constant step sizes is observed. The performance is further improved by optimizing nonlinear calculating position (NLCP) in case of using constant step sizes while NLCP optimization becomes unnecessary when using logarithmic step sizes, which reduces the computational effort due to uniformly distributed nonlinear phase for all successive steps. Copyright: © 2003-2012 . This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
lhft_intern.bib::Lin2012

Step-size selection for split-step based nonlinear compensation with coherent detection in 112-Gb/s 16-QAM transmission - Lin, Chien-Yu; Asif, Rameez; Holtmannspötter, Michael; Schmauß, Bernhard (Chinese Optics Letters, 2012)
Non-uniform step-size distribution is implemented for split-step based nonlinear compensation in single-channel 112-Gb/s 16 quadrature amplitude modulation (QAM) transmission. Numerical simulations of the system including a 20 × 80 km uncompensated link are performed using logarithmic step size distribution to compensate signal distortions. 50% of reduction in number of steps with respect to using constant step sizes is observed. The performance is further improved by optimizing nonlinear calculating position (NLCP) in case of using constant step sizes while NLCP optimization becomes unnecessary when using logarithmic step sizes, which reduces the computational effort due to uniformly distributed nonlinear phase for all successive steps.
lhft_intern.bib::Lin2012

STIREEM - A new High Resolution Microwave Imaging Principle - Brand, Hans; Martius, Siegfried; Schmidt, Lorenz-Peter; Schür, Jan; Weinzierl, Jochen; et al. (Proceedings of the German Microwave Conference, 2008)
UnivIS-Import:2015-04-16:Pub.2008.tech.IE.LEH.stiree_8

STIREEM - A Novel Technique for High Resolution Microwave Imaging - Brand, Hans; Dexl, A.; Hagen, Johannes; Kellnberger, S.; Martius, Siegfried; Schmidt, Lorenz-Peter; Schür, Jan; Weinzierl, Jochen (Proceedings of the European Microwave Association, 2008)
UnivIS-Import:2015-04-16:Pub.2008.tech.IE.LEH.stiree

Stocktaking Robots, Automatic Inventory, and 3D Product Maps: The Smart Warehouse Enabled by UHF-RFID Synthetic Aperture Localization Techniques - Gareis, Matthias; Parr, Andreas; Trabert, Johannes; Mehner, Tom; Vossiek, Martin; Carlowitz, Christian (IEEE Microwave Magazine, 2021)
In our age of global networks and the Internet of Things, communication and identification with a transponder tagged on goods and products have become increasingly important [1]. There is not only a need for the identification of the labeled objects but also for finding their exact positions in 3D space. Radio-frequency identification (RFID) offers both and is, in fact, already used in a vast field of applications, such as access control, goods logistics, indoor localization, automation, stocktaking, and many others [2]-[6]. Figure 1 illustrates a mobile robot platform for automatic inventory rounds that is used to acquire 3D product maps with ultrahigh-frequency (UHF)-RFID technolog
CRIS-Team Scopus Importer:2021-03-05

Stoerung der SAR-Verteilung von perkutanen Mikrowellen Waveguide Applikatoren durch Fehlanpassung - Erb, J; Engelbrecht, Rainer; Schaller, G; Seegenschmiedt, H; Mueller, R; Sauer, R; Bolmsjoe, M (1993)
lhft_intern.bib::thirty_years_LHFT_324

Störung der SAR-Verteilung von perkutanen Mikrowellen-Waveguide-Applikatoren durch Fehlanpassung - Erb, J.; Engelbrecht, Rainer; Schaller, Gerhard; Seegenschmiedt, Heinrich; Müller, R. G.; Sauer, R.; Bolmsjö, M. (24. Wissenschaftliche Tagung der Deutschen Gesellschaft für Medizinische Physik (DGMP), 1993)
UnivIS-Import:2015-04-16:Pub.1993.tech.IE.LEH.strung

Struktur, Eigenschaften und Anwendungen dielektrischer Leitungen für Millimeterwellen - Brand, Hans; Weinzierl, Jochen (Frequenz, 2001)
lhft_intern.bib::brand01

Sub-spatial resolution position estimation for optical fibre sensing applications - Zibar, Darko; Werzinger, Stefan; Schmauß, Bernhard (IEEE Sensors Conference, 2017)
Methods from machine learning community are employed for estimating the position of fibre Bragg gratings in an array. Using the conventional methods for position estimation, based on inverse discrete Fourier transform (IDFT), it is required that two-point spatial resolution is less than gratings' spacing. However, we show that by employing statistical inference methods in combination with adaptive gradient algorithm, it is still possible to estimate the grating positions even though this requirement is violated. No prior knowledge of the reflection coefficients is needed as the joint estimation of reflection coefficients and the positions is performed. From the practical point of view, we can demonstrate the reduction of the interrogator's bandwidth by factor of 2. The technique is demonstrated for incoherent optical frequency domain reflectometry (IOFDR). However, the approach is applicable to any other OFDR technique where bandwidth-resolution limitations of IDFT appl

Substituting bond wires by additively manufactured interconnections - Lomakin, Konstantin; Sippel, Mark; Gold, Gerald; Ringel, Johannes; Weiß, David; Helmreich, Klaus; Ankenbrand, Markus; Franke, Jörg (German Microwave Conference, 2018)
This work shows a comparison of microstrip to integrated circuits junction between conventional bond wires and additively manufactured signal interconnect. Therefore, an approach for reducing signal reflection is proposed and implemented on a test board fabricated on typical radio frequency substrate material. Measurements up to 24 GHz reveal improved performance as compared to conventional technology in terms of reflection suppression and transmission losse

Substrattechnologien für planar integrierte Mikro- und Millimeterwellenschaltungen - Schmidt, Lorenz-Peter; Methfessel, Sebastian Dirk; Schneiderbanger, Dirk; Rehner, Robert; Sterns, Michael; Kilian, Andreas; Nisznansky, Martin (Kooperationsforum Leiterplattentechnologie, Nürnberg, 22.01.2008, S. 95-124, 2008)
UnivIS-Import:2015-04-16:Pub.2008.tech.IE.LEH.substr

Subsurface TomoSAR imaging of the Mittelbergferner glacier in the Austrian Alps - Martin del Campo Becerra, Gustavo; Benedikter, Andreas; Amao-Oliva, Joel; Scheiber, Rolf (EUSAR 2021; 13th European Conference on Synthetic Aperture Radar, 2021)

Supercontinuum based absorption spectrometer for cycle-resolved multiparameter measurements in a rapid compression machine - Werblinski, Thomas; Kleindienst, Stefan; Engelbrecht, Rainer; Zigan, Lars; Will, Stefan (Applied Optics, 2016)
A broadband supercontinuum (SC) based absorption spectrometer capable of cycle-resolved multiparameter measurements at internal combustion (IC) engine conditions is presented. Three parameters, temperature, pressure and water mole fraction, were extracted from broadband near-infrared H2O" id="MathJax-Element-1-Frame" role="presentation" style="position: relative;" tabindex="0">H2O absorption spectra, spanning the wavelength-range from 1340 to 1405.5 nm, which exhibits a large number of specific H2O" id="MathJax-Element-2-Frame" role="presentation" style="position: relative;" tabindex="0">H2O transitions. The spectrometer is based on spatial domain detection and features a near-infrared line scan camera as a detector. Measurements were performed during a compression cycle of a rapid compression machine comprising a pressure and temperature range from 2.5 to 65 bar and 300 to 900 K, respectively. With the new spectrometer, we are for the first time, based on the authors’ knowledge, able to perform measurements based on SC radiation over a complete compression and expansion stroke at measurement rates up to 50 kHz. A detailed overview is provided about the best match algorithm between theory and experiments, including parameters from two different spectral databases, namely the Barber-Tennyson database (BT2) and HITRAN2012. The results indicate that spectral broadening effects are not properly described by theory, especially at pressure levels exceeding 20 bar, which culminates in a clear underestimation of the derived pressure data by SC absorption spectroscopy. Nevertheless, temperature can be determined accurately by performing a three-parameter fit based on water mole fraction, temperature, and pressure. In contrast, making use of pressure transducer data as look-up values and varying only temperature and H2O" id="MathJax-Element-3-Frame" role="presentation" style="position: relative;" tabindex="0">H2O mole fraction to find the best match leads to a clear overestimation of temperature at elevated pressure
lhft_intern.bib::Werblinski16

Super-Resolution Radar Imaging With Sparse Arrays Using a Deep Neural Network Trained With Enhanced Virtual Data - Schüßler, Christian; Hoffmann, Marcel; Vossiek, Martin (IEEE Journal of Microwaves, 2023)
This paper introduces a method based on a deep neural network (DNN) that is perfectly capable of processing radar data from extremely thinned radar apertures. The proposed DNN processing can provide both aliasing-free radar imaging and super-resolution. The results are validated by measuring the detection performance on realistic simulation data and by evaluating the Point-Spread-function (PSF) and the target-separation performance on measured point-like targets. Also, a qualitative evaluation of a typical automotive scene is conducted. It is shown that this approach can outperform state-of-the-art subspace algorithms and also other existing machine learning solutions. The presented results suggest that machine learning approaches trained with sufficiently sophisticated virtual input data are a very promising alternative to compressed sensing and subspace approaches in radar signal processing. The key to this performance is that the DNN is trained using realistic simulation data that perfectly mimic a given sparse antenna radar array hardware as the input. As ground truth, ultra-high resolution data from an enhanced virtual radar are simulated. Contrary to other work, the DNN utilizes the complete radar cube and not only the antenna channel information at certain range-Doppler detections. After training, the proposed DNN is capable of sidelobe- and ambiguity-free imaging. It simultaneously delivers nearly the same resolution and image quality as would be achieved with a fully occupied arra
Keywords: Neural networks; super-resolution; sparse antenna arrays; compressed sensing; self- supervised learning; radar simulation

Supporting manual assembly through merging live position data and 3D-CAD data using a worker information system - Meinel, D; Ehler, F; Lipka, Melanie; Franke, J (3. Fachkolloquium der Wissenschaftlichen Gesellschaft Montage, Handhabung, Industrierobotik, 2018)
Most of the existing worker information systems do not base the information on a worker’s real movement. By processing live sensor data through a novel Node.js server solution this link was established. This article describes an innovative worker information system with interactive access to real movements and target positions. Especially for assembling safety-relevant components and products, which are bearing a high risk of injury, live-controlled and recorded assembling holds advantages for quality and safety. Moreover, through shortened trainings the efficiency of the whole production system can be increased. The presented worker information system facilitates the employee at the example of a screwing proces
lhft_intern.bib::Lipka2018a

Suppression of Nonlinear Phase Noise in a DPSK Transmission Using a Nonlinear Amplifying Loop Mirror - Stephan, Christian; Sponsel, Klaus; Onishchukov, Georgy; Schmauß, Bernhard; Leuchs, Gerd (Optical Fiber Communication 2009, 2009)
Experimental and numerical investigations of phase-preserving amplitude regeneration in a DPSK transmission with a NALM have shown that a 3dB improvement of the Q-factor or alternatively a 3dB increase of fiber-launched power could be achieved. © 2009 IEEE.
UnivIS-Import:2017-12-18:Pub.2009.tech.IE.LEH.suppre

Surface functionalization allowing repetitive use of optical sensors for real-time detection of antibody-bacteria interaction. - Kutscher, Marika; Rosenberger, Manuel; Schmauß, Bernhard; Meinel, Lorenz; Lorenz, Udo; Ohlsen, Knut; Hellmann, Ralf; Germershaus, Oliver (Journal of Biophotonics, 2016)
In this study, sensor surface functionalization allowing the repetitive use of a sensing device was evaluated for antibody-based detection of living bacteria using an optical planar Bragg grating sensor. To achieve regenerable immobilization of bacteria specific antibodies, the heterobifunctional cross-linker N-succinimidyl 3-(2-pyridyldithio) propionate (SPDP) was linked to an aminosilanized sensor surface and subsequently reduced to expose sulfhydryl groups enabling the covalent conjugation of SPDP-activated antibodies via disulfide bonds. The immobilization of a capture antibody specific for Staphylococcus aureus on the sensor surface as well as specific binding of S. aureus could be monitored, highlighting the applicability of optical sensors for the specific detection of large biological structures. Reusability of bacteria saturated sensors was successfully demonstrated by cleaving the antibody along with bound bacteria through reduction of disulfide bonds and subsequent re-functionalization with activated antibody, resulting in comparable sensitivity towards S. aureus.

Surface Impedance Concept for Modeling Conductor Roughness - Gold, Gerald; Helmreich, Klaus (Proceedings of the IEEE MTT-S International Microwave Symposium 2015 (IMS 2015), 2015)
UnivIS-Import:2015-10-26:Pub.2015.tech.IE.c3scha.surfac

Switched Injection Locked Oscillator: A Novel Versatile Concept for Wireless Transponder and Localization Systems - Vossiek, Martin; Gulden, Peter (IEEE Transactions on Microwave Theory and Techniques, 2008)
In this paper, the novel principle of the switched injection-locked oscillator is introduced. It is shown that the concept is ideally suited for transponder and secondary radar systems with outstanding performance. A switched injection-locked oscillator transponder can produce an approximately phase coherent high-power response to an interrogating signal and, consequently, allows for long-range transponder systems and precise distance measurement between the reader and transponder. The simple and elegant round-trip time-of-flight measurement concept introduced in this paper enables innovative localization and navigation systems. Furthermore, it can be applied in numerous areas such as sensor networks, RF identification and localization, ubiquitous computing, location sensitive billing, context dependent information services, or tracking and guiding. © 2006 IEEE.
UnivIS-Import:2015-03-09:Pub.2008.tech.IE.LEH.switch
Keywords: Backscatter transponder; Oscillators; Radar; Radio navigation; Radio position measurement; RF identification (RFID); Secondary radar; Transponders

Synchronization of radar sensors in a network based on inter-sensor interference - Steiner, Maximilian; Keller, Manuel; Geiß, Johanna; Vossiek, Martin; Waldschmidt, Christian (EuRAD 2019 - 2019 16th European Radar Conference, 2019)
In networks of distributed radar sensors the measurements need to be synchronized to enable a joint processing and to avoid interference between the nodes. The proposed approach supersedes the distribution of a dedicated trigger cable by utilizing the multistatic target responses for time synchronization of the nodes. Each node is operated with a chirp-sequence modulation scheme, and the initial measurements are free running. The time-shifts between all sensors are recovered from the mutual interference of the nodes. The approach is verified by measurements that are conducted with three sensors, operated in the 77 GHz frequency band.
CRIS-Team Scopus Importer:2019-12-20

Synthesis of Angle Modulated Ultra Wideband Signals Based on Regenerative Sampling - Carlowitz, Christian; Vossiek, Martin (IEEE MTT-S International Microwave Symposium 2012 (IMS 2012), 2012)
For efficient low power UWB communication and ranging systems, fine grained control of the UWB signal spectral properties is desirable to maximize throughput and SNR at a given power budget and spectral mask. Simple impulse radio modulation techniques like pulse amplitude, binary phase or pulse position modulation usually do not provide the same flexibility and spectral efficiency as more complex angle modulation principles. The generation of angle modulated signals, however, is usually much more complex than for impulse radio transmitters. In this paper, a novel concept for the synthesis of pulsed angle modulated ultra wideband signals based on regenerative sampling is introduced that overcomes the above mentioned contradiction. The concept allows for generating arbitrarily phase modulated pulsed UWB signals with a low-complexity hardware. It is based on a switched injection locked oscillator that samples the phase from a high order harmonic of a phase modulated baseband signal. The signal synthesizer does not require any linear amplifiers or PLLs at RF frequency. This principle brings complex angle modulation to ultra wideband signals while at the same time retaining the feasibility of low power implementation. In this paper, this completely novel signal generation principle is introduced for the first time and its capability is theoretically and experimentally verified. © 2012 IEEE.
UnivIS-Import:2015-04-16:Pub.2012.tech.IE.LEH.synthe_1
Keywords: Injection-locked oscillators; Signal sampling; Ultra wideband communication; Ultra wideband technology

Synthesis of Pulsed Frequency Modulated Ultra Wideband Radar Signals Based on Stepped Phase Shifting - Carlowitz, Christian; Eßwein, Alexander; Weigel, Robert; Vossiek, Martin (IEEE International Conference on Ultra-Wideband, ICUWB 2012, 2012)
The current paper introduces a novel concept for low complexity and low power synthesis of pulsed frequency modulated ultra wideband (PFM UWB) signals. Instead of using a VCO-based synthesizer, we employ a simple digitally tuned phase modulator that varies the phase of a high order harmonic of a fixed frequency LO signal. The phase modulated harmonic is then injected into a switched injection locked pulse oscillator. Based on this concept, an arbitrary sequence of phase samples i.e. UWB pulses where each pulse has a predefined carrier phase can be generated. This sampled pulse sequence can be used for the generation of angle modulation schemes for communication signals and also for the generation of pulsed linear frequency modulated radar signals. The capability of the proposed concept is experimentally demonstrated for the synthesis of 6 to 8 GHz UWB pulsed frequency sweeps. Measurement results verify that this novel approach delivers a performance comparable to much more complex pulsed frequency modulation implementations. © 2012 IEEE.
UnivIS-Import:2015-04-16:Pub.2012.tech.IE.LEH.synthe
Keywords: Injection locked oscillators; radar; signal sampling; transponders; ultra wideband technology

Systematic distortions in electro-optical mixers - Gulden, Peter; Becker, Dirk; Vossiek, Martin (IEEE Sensors, 2003)
Electro-optical mixers (EOM) have tremendous potential for application in optical intensity-modulated time-of-flight distance measurement systems. Two different devices, Photonic Mixing Devices (PMD) and Metal-Semiconductor-Metal (MSM) are applied to distance measurement in this paper. The experimental results obtained show the presence of systematic distortions in the output signal of the device, resulting in measurement errors of up to a few centimeters. Careful analysis of the effects leads to the conclusion that illumination dependant non-linear effects take place inside local spots of the semiconductor. Consequently the introduction of a small diffusing plate for beam homogenization in front of the semiconductor drastically reduces the amount of systematic distortions. The distance measurement accuracy is doubled for PMDs, and even tripled for MSMs. Additionally the experimental data provides ties between charge injection mechanisms and the observed spurious signals.
UnivIS-Import:2015-04-16:Pub.2003.tech.IE.LEH.system_9
Keywords: Electro-optical mixer; Metal-semiconductor-metal technology (MSM); Photonic-mixing device (PMD); optical intensity-modulation (IM) time-of-flight distance measurement

Systematic Phase Correction for Direction-of-Arrival Estimation in Spectrally Interleaved OFDM MIMO Radar - Multerer, Thomas; Prechtel, U; Vossiek, Martin; Ziegler, Volker (IEEE Transactions on Microwave Theory and Techniques, 2019)
This paper presents a phase correction methodto improve direction-of-arrival (DOA) estimation in spectrallyinterleaved orthogonal frequency-division multiplexing (OFDM)multiple-input-multiple-output (MIMO) radar systems. It is newin the way that a phase correction step is introduced betweenthe range-Doppler processing and the DOA estimation. Thephase correction results in an improved dynamic range. Bothprocessing steps, range–velocity and DOA, are performed usingdiscrete Fourier transforms (DFTs). This paper starts by intro-ducing the waveform and reviewing range–velocity processing inOFDM radars. After that, the new phase correction method isintroduced. Then, the concept is implemented in a quantitativesimulation. The last part includes the system description andmeasurement in an outdoor scenario. Finally, the simulation andmeasurement results are discusse

Systematic Quality Assessment of Schottky Diodes for THz-Applications - Biber, Stephan; Cojocari, O.; Mottet, B.; Rehm, Guenther; Schmidt, Lorenz-Peter (3rd ESA Workshop on Millimetre Wave Technology and Applications, 2003)
UnivIS-Import:2015-04-16:Pub.2003.tech.IE.LEH.system

System Concept and Signal Processing for a 24 GHz Wireless SensorNetwork with Localization - Vossiek, Martin; Ebelt, R.; Shmakov, D. (International Conference on Communication and Signal Processing (CSP - SSD'12), 2012)
lhft_intern.bib::Vossiek2012

System concept for association and positioning of vehicles using SAW RFID tags - Caldero Bardaji, Pau; Zoeke, Dominik (EuRAD 2019 - 2019 16th European Radar Conference, 2019)
In this work we propose a system concept for simultaneous wireless identication and positioning of vehicles using SAW (surface acoustic wave) RFID (radio frequency identication) tags. Multichannel interrogation allows for additional extraction of vehicle orientation as well as resolution of ambiguities. The system is optimized for low-latency parallel interrogation with a measurement rate of 10 kHz to enable an accurate, real-time and unambiguous positioning with high statistical robustness, even for high-speed vehicles. Feasibility is demonstrated based on real experiments with tags mounted on an electronically controlled moving platform, showing its potential for localization and orientation measurements.
CRIS-Team Scopus Importer:2019-12-20
Keywords: Localization; Mobility; RFID; SAW

Systemkonzepte zur Mikrowellen-Energieuebertragung mittels Satelliten insbesondere zur Nutzung der Sonnenenergie - Brand, Hans (Seminar-Sonderheft "'Das Weltraumlabor Spacelab und seine Nutzung"', Lehrstuhl fuer Raumfahrttechnik, TU Muenchen, April, 1975)
lhft_intern.bib::thirty_years_LHFT_16

Taking a Look Beneath the Surface: Multicopter UAV-Based Ground-Penetrating Imaging Radars - Grathwohl, Alexander; Stelzig, Michael; Kanz, Julian; Fenske, Patrick; Benedikter, Andreas; Knill, Christina; Ullmann, Ingrid; Hajnsek, Irena; Moreira, Alberto; Krieger, Gerhard; Vossiek, Martin; Waldschmidt, Christian (IEEE Microwave Magazine, 2022)
The field of multicopter unmanned aerial vehicles (UAVs) has seen massive technological advances and decreasing costs over the last decade. Due to the higher prevalence and availability of these multicopter UAVs, there have also been rapid improvements in the software interfaceability, enabling the easy integration of custom software for flight planning and controllers. This opened up completely new possibilities, such as low-cost individual aerial photography, the most common civilian application. Furthermore, lightweight multicopters became widely accessible to the public, boosting the development of UAVs even more.<br

Taschenbuchs der HF-Technik (Meinke-Gundlach) - Schmidt, Lorenz-Peter; Adelseck, B (Taschenbuchs der HF-Technik (Meinke-Gundlach), 1986)
lhft_intern.bib::Schmidt14

Technik-Wissenschaft fuer das Jahr 2000 - Brand, Hans (1987)
lhft_intern.bib::thirty_years_LHFT_241

Technological Issues for Micromachining of New Passive THz-Components Based on Deep-Trench Silicon Etching - Biber, Stephan; Schür, Jan; Schmidt, Lorenz-Peter (29th International Conference on Infrared and Millimeter Waves, 2004)
We present a survey of the application of micromachining techniques for the fabrication of THz-components. Micro-machining of new THz- devices based on deep trench etching of silicon will be discussed with respect to its capability to generate complex 3-dimensional geometries with high aspect ratios (ARs) and to meet the high mechanical requirements for THz-components. First results for the application of deep trench etching for the design of a branch-line coupler for 600GHz will be discussed. We will emphasize the potential of silicon based microstructures for the manufacturing of new devices and focus on technological issues. © 2004 IEEE.
UnivIS-Import:2015-04-16:Pub.2004.tech.IE.LEH.techno

Teleophthalmology in Preventive Medicine - Höher, Bernhard; Michelson, Georg; Voigtmann, Peter; Schmauß, Bernhard (Teleophthalmology in Preventive Medicine, 2015)
lhft_intern.bib::Hoeher2015

Temperature and multi-species measurements by supercontinuum absorption spectroscopy for IC engine applications - Engelbrecht, Rainer; Will, Stefan; Werblinski, Thomas; Engel, Sascha; Zigan, Lars (Optics Express, 2013)
The first supercontinuum (SC) absorption spectroscopy measurements showing the feasibility of quantitative temperature evaluation are presented to the best of the authors' knowledge. Temperature and multi-species measurements were carried out at a detection rate of 2MHz in a high-temperature flow cell within a temperature range from 450K to 750K at 0.22MPa, representing conditions during the suction and compression stroke in an internal combustion (IC) engine. The broadband SC pulses were temporally dispersed into fast wavelength sweeps, covering the overtone absorption bands 2v1, 2v3, v 1 + v3 of H2O and 3v3 of CO 2 in the near-infrared region from 1330 nm to 1500 nm. The temperature information is inferred from the peak ratio of a temperature sensitive (1362.42 nm) and insensitive (1418.91 nm) absorption feature in the v1 + v3 overtone bands of water. The experimental results are in very good agreement with theoretical intensity ratios calculated from absorption spectra based on HiTran data. © 2013 Optical Society of America.
UnivIS-Import:2015-04-14:Pub.2013.tech.IE.LEH.temper_3

Temperature Referenced Planar Bragg Grating Strain Sensor in fs-Laser Cut COC Specimen - Rosenberger, Manuel; Roth, G. -L.; Adelmann, Benedikt; Schmauß, Bernhard; Hellmann, R. (IEEE Photonics Technology Letters, 2017)
We demonstrate a novel temperature referenced polymer Bragg grating (BG) sensor structure in planar cyclo-olefin copolymer (COC) substrate for tensile and compressive strain sensing. The sensor is based on two serial BGs UV-written into a specially designed planar COC substrate using a 248-nm-KrF laser. Successively, the temperature sensitivity and the behavior toward the tensile and compressive strain of both BGs are evaluated. Furthermore, we calculate the strain distribution in the COC specimen using a numerical simulation and discuss it with regard to the experimental result

Temperature Referenced Polymer Planar Bragg Grating for Strain Sensing - Rosenberger, M; Schmauß, Bernhard; Hellmann, R (Optical Sensors, 2016)
We report on the application of a temperature referenced polymer planar Bragg grating. The customized sensor consists of two cascaded gratings whereof one is used for measuring tensile strain and one serves as temperature referenc
lhft_intern.bib::rosenberger2016temperature

Temperature Sensitivity of Large Digital-Beamforming Multistatic mm-Wave Imaging Systems - Schießl, Andreas; Ahmed, Sherif Sayed; Genghammer, Andreas; Schmidt, Lorenz-Peter (IEEE International Microwave Symposium 2013, 2013)
Large multistatic mm-wave imaging systems have recently been developed and proved to be efficient for security applications. This work analyzes the effects caused by temperature changes on the imaging performance of a state-of-the-art system. The temperature dependent phase drift of a single measurement channel is characterized. A linearized model for the phase drifts in the RF channels is thus derived This model is applied to simulate for systematic phase drifts in the recorded raw data of the imaging system at different temperature profiles. Afterwards, images are reconstructed using modified raw data. Accordingly, the degradation in the imaging performance due to temperature changes is presented in terms of image quality and the associated point spread functions. © 2013 IEE
UnivIS-Import:2015-04-16:Pub.2013.tech.IE.LEH.temper
Keywords: Chip-on-board; Microwave imaging; Millimeter wave technology; Multichip modules; Temperature dependence

Temperatur- und Multi-Spezies-Messung in der Verbrennungstechnik mittels Supercontinuum-Absorptionsspektroskopie - Werblinski, Thomas; Engel, Sascha; Engelbrecht, Rainer; Zigan, Lars; Will, Stefan (Thermodynamik-Kolloquium 2013, 2013)

Terahertz-Research at the Erlangen University Laboratories for High Frequency Technology - Brand, Hans; Brune, J; Harth, A; Janker, R; März, M; Martius, Siegfried; Steup, D; Stoeckel, B (1994)
lhft_intern.bib::thirty_years_LHFT_329

Terahertz Synthetic Aperture Radar Imaging of Thermal Barrier Coatings on Metal Substrates - Ullmann, Ingrid; Oppelt, Daniel; Adametz, Julian; Schür, Jan; Vossiek, Martin (8th International Workshop on Terahertz Technology and Applications, 2018)
lhft_intern.bib::Ullmann18a

The Asymmetric Fiber Sagnac Interferometer as a Possibility of Noise-Reduction and Puls-Shaping in Modern High Bitrate Telecommunication Systems - Wietfeld, André; Meißner, Markus; Schmauß, Bernhard; Korolkova, Natalia; Leuchs, Gerd (DPG-Frühjahrstagung, 2001)
UnivIS-Import:2015-04-16:Pub.2001.tech.IE.LEH.theasy

The Best of Both Worlds: Merging the Benefits of Rack&Stack and Universal ATE - Lu, Ping; Glaser, Daniel; Uygur, Gürkan; Helmreich, Klaus (Conference Proceedings, 2009)
Test cost is and will continue to be one of the most important issues, especially in testing analog, mixed-signal and RF devices. When considering overall test cost, the key factors are low cost test equipment, low cost of ownership and low test development cost. Universal ATE ('big iron') is associated with high equipment cost but its powerful SW enables cost-efficient test development. Rack&Stack systems, on the other hand, can be assembled from inexpensive components, but load test engineers with much higher effort for test development and debug. This paper describes a concept that promises to combine the respective advantages of Rack&Stack and universal test systems by establishing a versatile test platform in HW based on industry standards enabling modular, least-cost, application-specific configuration with a likewise standard based SW environment for efficient test generation and debug, inherently supporting virtual test and test synthesis from formal specification. © 2009 IEEE.
UnivIS-Import:2015-04-16:Pub.2009.tech.IE.c3scha.thebes

The Degradation of Automotive Radar Sensor Signals Caused by Vehicle Vibrations and other Nonlinear Movements - Hau, Florian; Baumgärtner, Florian; Vossiek, Martin (Sensors, 2020)
As the demands on modern radar systems with respect to accuracy, reliability, and availability increase, a detailed assessment of the influence of nonlinear movements has become necessary. In particular, from the point of view of radar, different types of movements, such as any kind of acceleration, braking situation, or vehicle vibration, are essential parts of any traffic scenario. These unavoidable motions, in which the relative velocity changes within one measurement cycle, are called nonlinear movements. These nonlinearities contribute to intermediate frequencies, which are comparable to the extensively described nonlinearities of a frequency ramp. This additional contribution to the intermediate signal has a direct effect on the signal-to-noise ratio and thus on the accuracy and probability of target detection. This paper presents a study of various types of nonlinear motion and a detailed definition of the resulting parameters based on a variety of vehicle-based measurements. An advanced signal model of frequency-modulated continuous wave (FMCW) radar is introduced and verified in addition to a detailed mathematical description of spectral signal behaviour in sinusoidal motions and linear acceleration. The theoretical and experimental results in idealised point targets are transferred to real complex road users. Furthermore, by applying established automotive signal processing steps in the form of an ordered statistical constant false alarm rate (OS CFAR), the consequences of determining the noise level are also shown. In combination with the already introduced signal behaviour, these results enabled general description of the signal-to-noise ratio of nonlinear movements in complex traffic scenarios.
Keywords: automotive radar; frequency-modulated continuous wave (FMCW) radar; nonlinear movements; phase noise; degradation; signal-to-noise ratio (SNR)

The effect of phase noise on ranging uncertainty in FMCW secondary radar-based local positioning systems - Ebelt, R.; Shmakov, D.; Vossiek, Martin (9th European Radar Conference (EuRAD 2012), 2012)
In this paper, we present a closed-form expression for the lower bound of the ranging uncertainty in secondary FMCW radar based local positioning systems. This novel methodology uses a measured phase noise profile of the frequency ramp synthesizer and other readily available component and system parameters to calculate an analytical expression for a realistic estimate of the secondary radar performance. We show that the VCO phase noise is crucial for the lower performance limit of FM radar based local positioning systems. The analytical expressions and theoretical results are experimentally verified using a 24 GHz secondary radar hardware platform.
lhft_intern.bib::Ebelt2012

The Impact of Antenna Array Calibration Errors on MIMO and Multi-Channel Synthetic Aperture Radar Imaging - Geiß, Johanna; Sippel, Erik; Braunwarth, Michael; Vossiek, Martin (IEEE Journal of Microwaves, 2023)
In radar imaging, any lateral resolution is either attained using antenna arrays or by synthetic aperture radar (SAR) principles. Recently, the combination of both approaches to a multi-channel SAR (MCSAR) has gained increased attention. However, antenna arrays are impaired by unknown calibration errors, particularly phase errors, amplification deviations, mutual coupling, and phase center position deviation of the antenna element. Since, first, established calibration procedures are often non-ideal and, second, the calibration parameters usually vary over time due to aging and changes in temperature, calibration errors distort the measurements during the radar operation. Therefore, current research focuses on finding new practical calibration procedures. However, hardly any research has been conducted to analyze the basic effects which erroneous calibration parameters have on the reconstructed image in MCSAR or MIMO radar. In this work, we analyze the effects of multiple calibration error types on MCSAR and MIMO radar imaging. Both measurement principles lead to periodic error patterns, resulting in deterministic distortions. The derived relations can be used to precisely predict the position and number of ghost targets caused by calibration errors for known measurement setups and targets. For this, no information about the actual calibration errors is required. Furthermore, worst-case distortion levels are provided for different bounded errors allowing rough estimates of the impact of different error types on the image's distortion level. The findings are validated via measurements using a 76 GHz FMCW MIMO radar.<br
Keywords: Antenna arrays; Radar antennas; Radar imaging; Radar; Calibration; Antenna measurements; Synthetic aperture radar

The Limit of Downsizing Dielectric-Filled Slotted Waveguide Antennas - Bachbauer, Felix; Lomakin, Konstantin; Sippel, Mark; Gold, Gerald (2024 IEEE Wireless and Microwave Technology Conference, WAMICON 2024, 2024)
Miniaturization of a slotted waveguide antenna has its limits. Therefore, this paper examines the extent to which simple resonant waveguide slot antennas can be miniaturized using a dielectric filling and when the minimum size of the antenna is reached. To this end, the shrinking of the wavelength change due to the filling is initially considered. Afterwards, it is analytically shown, how this affects the function of the waveguide antenna. Then, suitable relative permittivity values for various applications are determined on the basis of given design values. Finally, an antenna is designed according to the previous considerations and then both manufactured and characterized.
CRIS-Team Scopus Importer:2024-05-31
Keywords: Additive manufacturing; dielectric filled waveguide; slot antenna; waveguide antennas

The New Frontiers of "Wireless Motion Capture and Fine-Scale Localization" - Buffi, Alice; Durgin, Gregory D.; Vossiek, Martin (IEEE Journal of Radio Frequency Identification, 2022)
CRIS-Team WoS Importer:2022-08-05

Theoretische und experimentelle Forschungen zum Kollisionsschutz im Straßenverkehr - Brand, Hans (1974)
lhft_intern.bib::thirty_years_LHFT_10

The Plastic Lightguide in Endoscopic Laser Photocoagulation - Reidenbach, H; Bodem, F; Fruehmorgen, P; Brand, Hans; Demling, L (Endoscopy, 1975)
Various core/cladding plastic lightguides have been investigated with respect to their optical properties and suitability for endoscopic photo-coagulation. Plastic fibres with a diameter of 1.5 mm and a polystyrene or polymethyl-methacrylate core proved to be best suited to meet the requirements of high optical-power performance, low optical attenuation, mechanical robustness, sufficient flexibility and capability of being integrated in existing endoscopes. No impairment of endoscopic manipulation could be observed in more than 200 endoscopic photo-coagulations performed in the canine gastrointestinal tract. The plastic fibre can easily be introduced into and withdrawn from the instrumental channel without restricting the flexibility of the endoscope. The easy sliding of the fibre within the instrumental channel permits a dynamic variation of the distance between fibre and tissue during a photocoagulation, thereby varying the spot size and power density of irradiation continuously. The optical and mechanical performance of the plastic fibre is far beyond the current requirements of laser endoscopy. The plastic fibre is thus a most promising and easy-to-handle optical transmission system for endoscopic photocoagulatio
lhft_intern.bib::thirty_years_LHFT_26

The Switched Injection-Locked Oscillator: A Novel Versatile Concept for Wireless Transponder and Localization Systems - Vossiek, Martin; Gulden, P (IEEE Transactions on Microwave Theory and Techniques, 2008)
In this paper, the novel principle of the switched injection-locked oscillator is introduced. It is shown that the concept is ideally suited for transponder and secondary radar systems with outstanding performance. A switched injection-locked oscillator transponder can produce an approximately phase coherent high-power response to an interrogating signal and, consequently, allows for long-range transponder systems and precise distance measurement between the reader and transponder. The simple and elegant round-trip time-of-flight measurement concept introduced in this paper enables innovative localization and navigation systems. Furthermore, it can be applied in numerous areas such as sensor networks, RF identification and localization, ubiquitous computing, location sensitive billing, context dependent information services, or tracking and guidin
lhft_intern.bib::Vossiek2008b

The TRIPLE Melting Probe - an Electro-Thermal Drill with a Forefield Reconnaissance System to Access Subglacial Lakes and Oceans - Heinen, Dirk; Audehm, Jan; Becker, Fabian; Böck, Georg; Espe, Clemens; Feldmann, Marco; Francke, Gero; Friend, Pia; Haberberger, Niklas; Helbin, Klaus; Nghe, Chi Thanh; Stelzig, Michael; et al. (OCEANS 2021: San Diego – Porto, 2021)
Recent measurements suggest the Jovian satellite Europa as one of the most promising places to host extraterrestrial life. Its global ocean is well hidden by a kilometer-thick layer of ice. Many currently discussed space missions therefore aim to explore Europa.The TRIPLE projects, initiated by the DLR Space Administration, comprise the development of Technologies for Rapid Ice Penetration and subglacial Lake Exploration, and consists of three components: (i) a melting probe, that travels through the ice and carries (ii) a small autonomous underwater vehicle (nanoAUV) that explores the ocean and takes samples to be delivered to (iii) an astrobiological laboratory. The full system should be demonstrated in a terrestrial analog mission in Antarctica in about five years. For a successful demonstration we need a retrievable melting probe capable of penetrating several kilometres of ice while avoiding obstacles and navigating around them. It has to be able to stop and dwell at the icewater boundary, before returning back to the surface. Within the projects TRIPLE-IceCraft and TRIPLE-FRS key technologies of such a melting probe are developed.The TRIPLE-IceCraft melting probe is designed as a modular system transporting standardised payloads through ice sheets of several hundred meters of thickness and penetrating into a subglacial water reservoir. Possible payloads are e.g. the nanoAUV or in-situ analysis devices for water samples such as a fluorescence spectrometer. The melting probe will be demonstrated at the Ekstrom shelf ice in Antarctica at the end of the project early 2023.The forefield reconnaissance system developed within TRIPLE-FRS combines radar and sonar techniques to benefit from both sensor principles inside ice. The radar antennas together with a specialized pulse amplifier as well as a piezoelectric acoustic transducer will be integrated into the melting head. To account for the respective propagation speed of electromagnetic waves, an in-situ permittivit...<br

Threat Object Classification with a Close Range Polarimetric Imaging System by Means of H-alpha Decomposition - Adametz, Julian; Schmidt, Lorenz-Peter (43th European Microwave Week, 2013)
In this paper, an approach to differentiate between various dielectric threat objects in security applications is investigated. The scattering information in form of the Sinclair matrix of relevant scenarios is gained from a fully polarimetric, monostatic synthetic aperture radar (SAR). A possible polarimetric calibration procedure is presented. The radar data are processed with the H-α decomposition algorithm. The H-α scattering characteristics of threat objects are analyzed in terms of a weighted averaging. It is shown that an object classification is possible even for threat objects conceiled under thick layers of clothing. Measurement results are presented to illustrate the topic. © 2013 EMA.
UnivIS-Import:2015-04-16:Pub.2013.tech.IE.LEH.threat

Threat object classification with a close range polarimetric imaging system by means of H-α decomposition - Adametz, Julian; Schmidt, Lorenz-Peter (International Journal of Microwave and Wireless Technologies, 2014)
lhft_intern.bib::Adametz2014c

THz Measurement Technologies and Applications - Schmidt, Lorenz-Peter; Biber, Stephan; Rehm, Guenther; Huber, Klaus (XIV International Conference on Microwaves, Radar and Wireless Communications, 2002)
UnivIS-Import:2015-04-16:Pub.2002.tech.IE.LEH.thzmea

Tight Non-Radiating Bends of 3D-Printed Dielectric Image Lines Based on Electromagnetic Bandgap Mirrors - Hahn, Leonhard; Bader, Tobias; Carlowitz, Christian; Vossiek, Martin; Gold, Gerald (2024 IEEE Wireless and Microwave Technology Conference (WAMICON), 2024)
This paper reports on a novel compact, low-loss bending technique for additively manufactured dielectric image lines between 140 GHz and 220 GHz. Conventional bending approaches require either large curvature radii or technologically challenging permittivity variations to prevent radiation loss at line discontinuities, e.g. caused by narrow bends. In contrast, this work uses extremely compact, easy-to-manufacture electromagnetic bandgap (EBG) cells to solve the afore mentioned challenge for the first time. These offer excellent reflection properties and thus enable broadband and low-loss (IL < 1 dB) guidance of electromagnetic waves by means of total reflection. Without increasing the complexity of the process, both the high-pass behaviour and the enormous space requirement of conventional dielectric bends are completely avoided. In addition, the use of EBGs improves the mutual isolation of dielectric image lines of up to 30 dB. Therefore, a promising solution for the realization of narrow, 3D-printed, low-loss signal distribution networks in the sub-THz domain is offered.<br
Keywords: Wireless communication; Microwave technology; Bending; Reflection; Metamaterials; Dielectrics; Mirrors; Dielectric image lines; electromagnetic bandgap; 3D-printing; low-loss; bending structures; sub-THz

Time and Frequency Synchronization for Real-Time Wireless Digital Communication Systems - Ghasemi, Roghayeh; Kögel, Tobias; Fenske, Patrick; Schober, Robert; Vossiek, Martin (2024 15th German Microwave Conference, GeMiC 2024, 2024)
In this paper, we present a fully field-programmable gate array (FPGA)-based real-time implementation of a wireless time and frequency synchronization scheme for communication and sensor networks. For this purpose, a communication link using frequency division multiplexing is established between three distributed stations. This allows the simultaneous and continuous transmission of quadrature phase-shift keying-modulated data between the stations with no interference. The time difference between the stations is estimated using the precision time protocol. Due to the deterministic processing time of the FPGA implementation, precise time synchronization is achieved, with a standard deviation of 10 ns per communication cycle. Moreover, in the proposed method, successive estimates of the time offset are used to estimate the frequency difference between the stations, which allows the tuning of the digitally controlled crystal oscillators of the distributed stations to the frequency of the central reference station, with a clock rate deviation of approximately two parts per billion. The structure is robust with respect to multi path interference and is extendable to additional frequency bands and stations. The results demonstrate the excellent performance and robustness of the proposed concept.
CRIS-Team Scopus Importer:2024-04-26
Keywords: Costas loop; field-programmable gate array (FPGA); Precision Time Protocol (PTP); time and frequency synchronization; wireless communication network; wireless synchronization

Time and Wavelength Division Multiplexing of Branched Fiber Bragg Grating Arrays - Härteis, Lisa-Sophie; Renner, Esther; Schmauß, Bernhard (2020)

Time and wavelength division multiplexing of fiber Bragg gratings with bidirectional electro-optical frequency conversion - Werzinger, Stefan; Härteis, Lisa; Köppel, Max; Schmauß, Bernhard (International Conference on Optical Fibre Sensors (OFS), 2018)

Time-Domain Based Absorption Spectroscopy: A Comparison of ns-and ps-Pumped Supercontinuum Sources for IC Engine Applications - Werblinski, Thomas; Engelbrecht, Rainer; Engel, Sascha; Will, Stefan; Zigan, Lars (European Combustion Meeting 2013, 2013)
lhft_intern.bib::werblinski13

Time-of-Flight 3-D Endoscopy - Penne, Jochen; Höller, Kurt Emmerich; Stürmer, Michael; Schrauder, Thomas; Schneider, Armin; Engelbrecht, Rainer; Feußner, Hubertus; Schmauß, Bernhard; Hornegger, Joachim (Springer-verlag, 2009)
This paper describes the first accomplishment of the Time-of-Flight (ToF) measurement principle via endoscope optics. The applicability of the approach is verified by in-vitro experiments. Off-the-shelf ToF camera sensors enable the per-pixel, on-chip, real-time, marker-less acquisition of distance information. The transfer of the emerging ToF measurement technique to endoscope optics is the basis for a new generation of ToF rigid or flexible 3-D endoscopes. No modification of the endoscope optic itself is necessary as only an enhancement of illumination unit and image sensors is necessary. The major contribution of this paper is threefold: First, the accomplishment of the ToF measurement principle via endoscope optics; second, the development and validation of a complete calibration and post-processing routine; third, accomplishment of extensive in-vitro experiments. Currently, a depth measurement precision of 0.89 mm at 20 fps with 3072 3-D points is achieved. © 2009 Springer-Verlag.
UnivIS-Import:2015-04-16:Pub.2009.tech.IMMD.IMMD5.timeof_24

Time-Resolved Measurement of Gas Parameters inside Diffusion-Cooled CO_2 Lasers with NIR Diode Laser and UV-VIS Emission Spectroscopy - Engelbrecht, Rainer; Schulz, J. (Proceedings of the SPIE, Vol. 4184 (XIII Int. Symp. on Gas Flow and Chemical Lasers and High Power Laser Conference, Florenz 2000), 2000)
UnivIS-Import:2015-04-16:Pub.2000.tech.IE.LEH.timere

Time-resolved measurement of gas parameters inside diffusion-cooled CO 2 lasers with NIR diode laser and UV-VIS emission spectroscopy - Engelbrecht, Rainer; Schulz, J (SPIE, Vol. 4184 (XIII Int. Symp. on Gas Flow and Chemical Lasers and High Power Laser Conference, Florenz 2000), 2001)
Time-resolved gas dissociation inside diffusion-cooled RF excited CO2 lasers was measured with NIR laser absorption spectroscopy and UV-VIS emission spectroscopy. Roto-vibrational temperatures were derived directly in the discharge region. Effects of gas additives on the plasma processes were studied. © (2001) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
lhft_intern.bib::engelbrecht00a

Time-Synchronized Joint Communication and Precise Wireless Localization of Multiple On-Body Sensor Nodes for Human Gait and Movement Measurement - Schlechtweg, Niklas; Brückner, Stefan; Gambietz, Markus; Koelewijn, Anne; Vossiek, Martin (Asilomar Conference on Signals, Systems, and Computers, 2024)

TiO2 surface functionalization of COC based planar waveguide Bragg gratings for refractive index sensing - Rosenberger, Manuel; Girschikofsky, M.; Förthner, Michael; Belle, S.; Rommel, Mathias; Frey, Lothar; Schmauß, Bernhard; Hellmann, R. (Journal of Optics, 2018)
We demonstrate the applicability of a planar waveguide Bragg grating in cyclo-olefin copolymer (COC) for refractive index sensing. The polymer planar waveguide Bragg grating fabricated using a single writing step technique is coated with a high-index layer of titanium dioxide (TiO2) leading to a distinct birefringence. This in turn results in the splitting of the Bragg reflection into two distinct Bragg wavelengths, which strongly differ regarding their refractive index sensitivities. Where one wavelength is only slightly affected by the ambient refractive index, the second Bragg peak shows a strong sensitivity. Furthermore, we investigate the temperature behaviour of the functionalized sensor and discuss it with respect to applications in refractive index sensin
Keywords: Bragg grating; high index layer; integrated waveguide; polymer optics; refractive index sensing

Tip Clearance Measurement Technique for Stationary Gas Turbines Using an Autofocusing Millimeter-Wave Synthetic Aperture Radar - Schicht, Andreas; Schwarzer, Stefan; Schmidt, Lorenz-Peter (IEEE Transactions on Instrumentation and Measurement, 2012)
In this paper, an autofocusing radar technique is presented for tip clearance measurements in combustion turbines capable of resolving the edges of a typical blade tip. The clearance is determined by measuring the reflection at the blade tip while passing by the antenna, subsequently focusing the data by means of a matched filter operation and interpreting the phase of the blade edge reflection according to the continuous wave radar principle. For this, an autofocus approach was developed, which minimizes defocusing effects and provides an estimate of the clearance as the first result, which is utilized to overcome the phase ambiguity and, thus, to increase the measurement range. The autofocus algorithm applies a weighted phase gradient of the pointlike blade edge reflection as cost function and sensitive indicator for the focal qualit
lhft_intern.bib::Schicht2012

TOPAS based humidity insensitive polymer planar Bragg gratings for temperature and multi-axial strain sensing - Rosenberger, M.; Hessler, S.; Belle, S.; Schmauß, Bernhard; Hellmann, R. (International Seminar on Photonics, Optics, and Its Applications (ISPhOA 2014), 2015)
We demonstrate the application of humidity insensitive polymer planar Bragg gratings written into planar TOPAS substrates for measuring temperature as well as multi-axial tensile and compressive strain. The polymer planar Bragg gratings are realized by a rapid fabrication process using a KrF excimer laser which illuminates a stacked mask configuration consisting of an amplitude mask and a phase mask with a grating period of 1036.79 nm. We determine the UV-induced refractive index modification of the integrated waveguide by phase shifting Mach Zehnder interferometry and investigate its light guiding properties. The integrated polymer planar Bragg grating (PPBG) reflects a wavelength of 1576.5 nm with a reflectivity of about 93% and shows almost no sensitivity against relative humidity. Therefore, the TOPAS-PPBG is well-suited for measuring temperature as well as tensile and compressive strain. Temperature measurements are feasible up to 116°C. An observed temperature hysteresis disappears after three consecutive temperature cycles, after which the TOPAS-PPBG is characterized by a sensitivity of -6.5 pm/°C. Furthermore, tensile and compressive strain is applied at different angles showing an angle-dependent sensitivity of the PPBG making it a suitable candidate for multi-axial strain sensing. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use onl
lhft_intern.bib::Rosenberger2015_2

Towards 3D-Printed Antenna in Package Solutions for THz-Applications - Pfahler, Tim; Gold, Gerald; Hofmann, Andreas; Schür, Jan; Vossiek, Martin (2024 IEEE International Conference on Microwaves, Communications, Antennas, Biomedical Engineering and Electronic Systems, COMCAS 2024, 2024)
This work investigates the feasibility of 3D-printing packages for integrated circuits (IC) with built-in functional structures. The principle is demonstrated with a 300 GHz package integrated horn antenna. The horn in package is used for beamforming and antenna gain enhancement of system-on-chip (SoC) solutions and is fed by an on-chip patch antenna implemented in Backend-of-line (BEOL). The paper highlights the design process of the on-chip driver element, the 3D-printed package, and the assembly of the module. The functionality of the on-chip antenna, waveguide package horn and assembly is verified by measurement characterization. Furthermore, the limitations of current 3D-printing technologies in terms of resolution capabilities and the advantages of 3D-printed IC-packages, encapsulations, and interconnects for future wideband communications and high-resolution radar sensor applications above 300 GHz will be discussed.
CRIS-Team Scopus Importer:2024-10-18
Keywords: 3D-printing; additive manufacturing; antenna in package; chip-to-waveguide transitions; encapsulation; integrated circuit packaging; on-chip antenna; three dimensional printing

Towards Continuous Real-Time Plant and Insect Monitoring by Miniaturized THz Systems - Sheikh, Fawad; Prokscha, Andreas; Batra, Aman; Lessy, Dien; Salah, Baha; Sievert, Benedikt; Degen, Marvin; Rennings, Andreas; Jalali, Mandana; Svejda, Jan Taro; Alibeigloo, Pooya; Preuss, Christian; et al. (IEEE Journal of Microwaves, 2023)
In this paper, new concepts for continuous 24/7 real-time monitoring of plants and insects with miniaturized terahertz (THz) systems are described and experimentally tested. Thus, for the first time, small-scale insights into the instantaneous plant health but also in their long-term growth can be obtained. Using such compact THz systems, e.g. water uptake, insect infestation and the behavior of pollinators (i.e. honey bees) and pests can be measured dynamically and non-invasively at virtually any position in the close biotope surrounding them. In addition to general understanding, this can be used to optimize crop yield and reduce resource consumption as well as for identifying characteristics of insect-plant interactions induced by potential environmental stressors. Given such a holistic approach, the proposed concepts may provide a significant advancement in environmental monitoring technology.<br
Keywords: Insects; Monitoring; Temperature measurement; Biomedical monitoring; Temperature sensors; Detectors; Real-time systems

Towards Detecting Climate Change Effects With UAV-Borne Imaging Radars - Ullmann, Ingrid; Bonfert, Christina; Grathwohl, Alexander; Lahmeri, Mohamed Amine; Mustieles Perez, Victor; Kanz, Julian; Sterk, Elena; Bormuth, Frederik; Ghasemi, Roghayeh; Fenske, Patrick; Villano, Michelangelo; Schober, Robert; et al. (IEEE Journal of Microwaves, 2024)
Climate change is associated with a variety of environmental phenomena, such as the melting of glaciers, the drying out of crops and soils, and an increase in the risk of avalanches. To detect and monitor these changes, satellite-based radar imaging is widely used, as it enables the large-scale mapping of the Earth's surface independent of weather and sunlight. An emerging field of research is to use radar systems mounted on unmanned aerial vehicles (UAVs) for this purpose. UAV-borne radar systems image smaller areas, but can capture them in greater detail, more flexibly in terms of flight trajectory, and at shorter repetition intervals. This article presents the capabilities of UAV-based radar systems and the associated challenges in terms of system design and imaging techniques for detecting and monitoring the effects of climate change. Current research results are shown. In addition, we give an outlook on using a swarm of cooperative UAVs, each carrying a radar. UAV swarms will enable a higher imaging quality with respect to resolution and detectability, but at the same time come with a number of additional challenges, which will be discussed in the paper as well.
CRIS-Team Scopus Importer:2024-09-27
Keywords: Climate change; microwaves in climate change; radar; radar imaging; remote sensing; UAV

Towards Dielectric Chip-to-Chip Interconnects for THz Applications - Bader, Tobias; Gold, Gerald (2024 IEEE Wireless and Microwave Technology Conference, WAMICON 2024, 2024)
In this article a novel concept of a dielectric chip-to-chip interconnect utilizing a dielectric image line is described. It is implemented by connecting two differential transmission lines, e.g. located at two ICs using an automated additive extrusion process to connect the two components. Therefore, transitions, i.e. wave mode transducers from the differential microstrip to the dielectric image line mode are developed. The 60mm long dielectric image line and two of the developed transducers show a deembedded insertion loss of around 4 dB from 100 to 110 GHz. This may point the way to novel interconnects for frequency ranges from a few hundred GHz to the THz range, where conventional stripline technology would be disadvantageous.
CRIS-Team Scopus Importer:2024-05-31
Keywords: additive manufacturing; chip to chip connection; dielectric image line; transition; wavemode transducer

Towards Pressure Sensors Based on Polymer Planar Bragg Gratings - Kefer, Stefan; Pape, Natalie; Gries, Nikola; Roth, Gian Luca; Schmauß, Bernhard; Hellmann, Ralf (Proceedings of SPIE - The International Society for Optical Engineering, 2023)
While Bragg grating-based optical devices have shown promising performances for pressure sensing applications, their sensitivity, especially in the low-pressure regime, is unsatisfying and needs to be optimized by elaborate designs, such as cantilevers or other extrinsic mechanical transducers. This contribution demonstrates and discusses a novel concept for optical pressure sensors based on polymer planar Bragg gratings. Waveguide and Bragg grating are fabricated underneath the surface of a temperature-stable and humidity-insensitive cyclic olefin copolymer substrate by means of a femtosecond laser. Based on the employed direct-writing procedure, in combination with adaptive, in-situ beam shaping with a spatial light modulator, writing depth, i.e., location of the photonic structures within the substrate, as well as Bragg grating periodicity and positioning can be deliberately chosen. Afterwards, the polymer substrate is post-processed with a high-precision micro mill, so a diaphragm comprising the integrated photonic structures is generated. The resulting diaphragm exhibits a thickness of 300 µm and a diameter of 10 mm. Finally, the optical sensor is packaged and sealed to form an air-filled gas pocket underneath the diaphragm. Deformations of the diaphragm by external pressure changes translate to strain variations along the waveguide axis and thus perturb the Bragg grating period. This leads to changes in the grating's wavelength of main reflection, which can be evaluated in order to quantify the relative external pressure. With this straightforward optical sensor concept, pressure sensitivities up to 39 pm kPa-1, within relative pressures ranges from -78 kPa to 372 kPa, are achieved.
CRIS-Team Scopus Importer:2023-06-02
Keywords: Bragg Grating; Cyclic Olefin Copolymers; Direct Writing; Femtosecond Laser; Integrated Photonics; Precision Milling; Pressure Sensor

Towards the Validation of a Volumetric Imaging Concept for the SAR Exploration of Enceladus - Benedikter, Andreas; Rodriguez-Cassola, Marc; Krieger, Gerhard; Scheiber, Rolf; Martin del Campo Becerra, Gustavo; Horn, Ralf; Moreira, Alberto; Stelzig, Michael; Vossiek, Martin (AGU Fall Meeting 2019, 2019)

Transfer learning for temperature predictions in sensors employing fibre Bragg grating arrays - Djurhuus, Martin S.E.; Schmauß, Bernhard; Clausen, Anders T.; Zibar, Darko (Optics InfoBase Conference Papers, 2020)
The feasibility of transfer learning is experimentally demonstrated by accurate predictions of temperatures of FBGs excluded from the training process with SMSE in the 10-3 range even for FBG peak powers around -30 dBm.
CRIS-Team Scopus Importer:2024-12-16

Transmission Line Model for Rectangular Waveguides accurately incorporating Loss Effects - Lomakin, Konstantin; Gold, Gerald; Helmreich, Klaus (21st IEEE Workshop on Signal and Power Integrity (SPI 2017), 2017)

Transmission Loss Analysis of Unidirectional Carbon Fiber-Reinforced Polymers for Millimeter Waves for Linear and Circular Polarization - Dorbath, Benedikt; Schür, Jan; Vossiek, Martin (IEEE Transactions on Microwave Theory and Techniques, 2023)
Carbon fiber-reinforced polymers (CFRPs) shape numerous industrial-and consumer-oriented products that benefit from lightweight construction while maintaining high durability. Electromagnetic waves transmitted through such conductive CFRPs experience strong attenuation that largely depends on the internal structure of the composite material. Therefore, we investigated the absorption loss of different unidirectional CFRP specimens with various numbers of carbon fiber (CF) plies and thicknesses. The results are presented for linear polarization (LP) and circular polarization (CP), and different orientations of the specimens at 45 GHz. Compared with LP, the transmission characteristics of CP hardly depend on the anisotropic character of unidirectional fiber plies. We observe that the absorption loss is mostly dependent on the number of conductive CF plies rather than the fiber volume ratio (FVR) of the sample. We present a multilayer homogeneous model that assigns an effective conductivity to a CF ply. The model assumes an alternation between dielectric epoxy resin and conductive CF plies. Iteratively, the effective conductivity of the conductive layers, in which the modeling results best fit the measurement results, is determined. In practice, this calculated effective layer conductivity can be used to estimate the transmission loss or shielding effectiveness of products made of CFRPs. The solver time of simulations becomes manageable by applying the multilayer simplification. For the first time, to the best of authors’ knowledge, effective conductivity values of CFs and their composites are presented at such high frequencies.<br

Transmission of two mode coded channels in one fibre using optical directional couplers as mode selective elements - Schmauß, Bernhard (Optical and Quantum Electronics, 1992)
Mode multiplexing, a method for transmitting two signals along one fibre without time-or wavelength-multiplexing is presented with theoretical and experimental results. It is shown that two mode coded channels can be separated using optical directional couplers with enhanced mode selectivity combined with a simple signal processing uni
lhft_intern.bib::thirty_years_LHFT_292

Transmissionsmessung nach Betrag und Phase mit einem homodynen Empfänger im Sub-Millimeterwellen-Bereich - Rehm, Guenther; Schmidt, Lorenz-Peter (Frequenz, 2001)
UnivIS-Import:2015-03-09:Pub.2001.tech.IE.LEH.transm

Transponder and Reader Concept for a HF Locating System - Schäfer, Tobias; Vossiek, Martin (6th German Microwave Conference (GeMiC) 2011, 2011)
This paper presents a low-frequency local positioning system operating at 13.56 MHz. With a wavelength of around 22 m the system operates in the near field. The phase shift between a CW signal generated at the base station and the response generated in a transponder is measured. The transponder is using the novel switched injection locked oscillator concept (SILO). Measurement results show that the proposed concept allows for robust indoor ranging with an uncertainty in the decimeter-range. 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.
lhft_intern.bib::Schaefer2011

Transversely Pumped CW Submillimeterwave-Laser with Sandwich Resonator - Harth, A; Brand, Hans (1992)
lhft_intern.bib::thirty_years_LHFT_296

Travel Time Computation in Snow and Ice Volumes for Radar Remote Sensing Applications - Benedikter, Andreas; Huber, Christian; Gambacorta, Letizia; Rodriguez-Cassola, Marc; Krieger, Gerhard (IEEE Geoscience and Remote Sensing Letters, 2025)
When radar signals penetrate snow and ice, they experience additional delays and directional changes due to the higher refractive index compared to that of air. These propagation effects should be taken into account accurately when processing, simulating, or geocoding radar data. Travel time computation is straightforward when the refractive index is constant, but it becomes challenging in heterogeneous media. This letter introduces novel methods based on the Eikonal equation and Fermat's principle for efficiently computing radar signal travel times in heterogeneous snow and ice volumes. These approaches can accommodate nearly arbitrary refractive index distributions, ensuring precise handling of propagation effects in radar remote sensing applications.
CRIS-Team Scopus Importer:2025-04-25
Keywords: ice; propagation effects; Radar; refraction; SAR; snow

Tunable Bulk Polymer Planar Bragg Gratings Electrified via Femtosecond Laser Reductive Sintering of CuO Nanoparticles - Kefer, Stefan; Bischoff, Kay; Roth, Gian Luca; Haubner, Julian; Schmauß, Bernhard; Hellmann, Ralf (Advanced Optical Materials, 2021)
This contribution demonstrates and discusses electrically tunable polymer planar Bragg gratings based on bulk cyclic olefin copolymers. A lithographic single-writing-step method and femtosecond laser reductive sintering of copper(II) oxide nanoparticles are subsequently employed in order to generate buried photonic structures and copper conducting paths on top of the polymer substrate. This way, the necessary number of process steps for fabricating a planar polymer-based electro-optical device is greatly reduced. The response of a fully electrified grating structure follows temperature changes, induced by the copper conducting path, with sensitivities up to −31 pm K−1. Dilatometric measurements show that the specimen's behavior is correlated to the situationally reduced thermal expansion of the bulk polymer substrate. In consequence, the tuning response of the photonic platform follows a second order polynomial, whereas a direct current of 30 mA, which correlates to a power consumption of 18.3 mW, leads to a local temperature increase and a residual Bragg wavelength shift of 19.6 K and −547 pm, respectively. Moreover, the outstanding flexibility of the proposed fabrication concept is underlined by demonstrating alternative conducting path geometries, whereas one of the additional designs is adapted to control the spectral width of the Bragg grating's reflection peak.
CRIS-Team Scopus Importer:2021-04-19
Keywords: Bragg gratings; CuO nanoparticles; cyclic olefin copolymers; electro-optic tuning; integrated photonics; laser reductive sintering

Tunable millimetre-wave ferrite bandpass filter with reduced biasing field - Brand, Hans; Krause, N (Electronics Letters, 1977)
lhft_intern.bib::thirty_years_LHFT_66

Turbo differential decoding failure for a coherent phase slip channel - Bisplinghoff, Andreas; Langenbach, S.; Kupfer, T.; Schmauß, Bernhard (38th European Conference and Exhibition on Optical Communication (ECOC), 2012)
We study the impact of stressors such as phase slips on the performance of LDPC codes with differentially encoded coherent DP-QPSK, comparing classical soft-decision decoding and iterative (turbo) differential decoding. We find that turbo decoding shows improved baseline performance but suffers from severely reduced phase slip resilienc
lhft_intern.bib::Bisplinghoff2012a

Two-Component Scattering Decomposition Technique for Walk-Through Security Scanners Using a Copolarized-MIMO Array - Root, Konstantin; Ullmann, Ingrid; Vossiek, Martin (2024 21st European Radar Conference, EuRAD 2024, 2024)
The widespread deployment of walk-through security scanners necessitates high reliability and a minimal false-alarm rate. This paper proposes a novel approach to improve existing systems by distinguishing between two scattering processes encountered during security checks: reflections from skin versus reflections from concealed objects. As skin shows specular reflection behavior, whereas objects tend to reflect diffuse, reconstruction results of the same scene with different array geometries show different imaging results. Therefore, we separate the imaging array into multiple partial arrays that exploit this scattering behavior beneficially. After obtaining the different reconstruction images, we propose an image processing technique that allows to obtain information about object reflections in the scene. This technique uses existing state-of-the-art walk-through scanners without the need for hardware modifications and hence, can easily be integrated. We validate the efficiency of this approach through realistic measurements involving human subjects and various threat objects. Our results demonstrate the capability to detect these objects, offering promise to improve existing systems.
CRIS-Team Scopus Importer:2024-12-13
Keywords: MIMO radar; personnel screening; radar imaging; scattering decomposition; security scanning

Two Stage Extended Kalman Filtering for Joint Compensation of Frequency Offset, Linear and Nonlinear Phase Noise and Amplitude Noise in Coherent QAM Systems - Pakala, Lalitha; Schmauß, Bernhard (ICTON 2017, 19th International Conference on Transparent Optical Networks, 2017)

Typical Offset of Usable Antenna Bandwidth due to Surface Roughness - Gold, Gerald; Engel, Lukas (22nd IEEE Wireless and Microwave Technology Conference (WAMICON), 2022)

UAV Formation Optimization for Communication-Assisted InSAR Sensing - Lahmeri, Mohamed Amine; Mustieles Perez, Victor; Vossiek, Martin; Krieger, Gerhard; Schober, Robert (IEEE International Conference on Communications, 2024)
Interferometric synthetic aperture radar (InSAR) is an increasingly important remote sensing technique that enables three-dimensional (3D) sensing applications such as the generation of accurate digital elevation models (DEMs). In this paper, we investigate the joint formation and communication resource allocation optimization for a system comprising two unmanned aerial vehicles (UAVs) to perform InSAR sensing and to transfer the acquired data to the ground. To this end, we adopt as sensing performance metrics the interferometric coherence, i.e., the local correlation between the two co-registered UAV radar images, and the height of ambiguity (HoA), which together are a measure for the accuracy with which the InSAR system can estimate the height of ground objects. In addition, an analytical expression for the coverage of the considered InSAR sensing system is derived. Our objective is to maximize the InSAR coverage while satisfying all relevant InSAR-specific sensing and communication performance metrics. To tackle the non-convexity of the formu-lated optimization problem, we employ alternating optimization (AO) techniques combined with successive convex approximation (SCA). Our simulation results reveal that the resulting resource allocation algorithm outperforms two benchmark schemes in terms of InSAR coverage, while satisfying all sensing and real-time communication requirements. Furthermore, we highlight the importance of efficient communication resource allocation in facilitating real-time sensing and unveil the trade-off between InSAR height estimation accuracy and coverage.
CRIS-Team Scopus Importer:2024-09-13

UHF RFID Localization Based on Synthetic Apertures - Miesen, Robert; Kirsch, Fabian; Vossiek, Martin (IEEE Transactions on Automation Science and Engineering, 2013)
Reading ranges are being extended in the wake of recent advances in UHF radio frequency identification (RFID) systems, and with the advent of larger reading ranges, tag localization has moved into the spotlight. Recently, we introduced a new UHF RFID tag localization technique. The proposed method is based on phase measurements taken along a synthetic aperture. A holographic image is calculated based on the scanned phase values. The image represents the spatial probability density function for the actual tag location. This paper presents this innovative method in detail. Simulations that illustrate the effect of the given trajectory are included. Extensive measurements obtained in a reflective lab environment are presented. We discuss the method's effectiveness with respect to measurement errors, antenna phase center distortions, and the available phase information. The results show the potential practical applications for the method in moving reader antennas, such as handheld readers or readers mounted on vehicles like forklifts or mobile robotic systems. © 2012 IEEE.
UnivIS-Import:2015-03-09:Pub.2013.tech.IE.LEH.uhfrfi
Keywords: Holography; Image reconstruction; Position measurement; Radio frequency identification (RFID); Radio navigation; Synthetic aperture radar; Transponders

Ultrahigh-Performance Radio Frequency System-on-Chip Implementation of a Kalman Filter-Based High-Precision Time and Frequency Synchronization for Networked Integrated Sensing and Communication Systems - Ghasemi, Roghayeh; Fenske, Patrick; Kögel, Tobias; Hehn, Markus; Ullmann, Ingrid; Vossiek, Martin (IEEE Open Journal of Instrumentation and Measurement, 2025)
The integration of radar sensing and imaging capabilities into future integrated sensing and communication (ISAC) networks enables advanced use cases, including autonomous vehicle navigation, real-time health monitoring, and smart city management. However, ultraprecise time and frequency synchronization is crucial for unlocking the full potential of such networked ISAC systems. In this article, a novel real-time wireless time and frequency synchronization scheme is developed and fully implemented on a high-end radio frequency system-on-chip field-programmable gate array (FPGA) platform. The excellent performance and robustness of the proposed solution in practical applications are demonstrated. It is evidenced that the recursive nature of the Kalman filter is well suited to the dynamic capabilities of FPGA-based simultaneous synchronization. Observed values obtained through the precision time protocol (PTP) are iteratively refined, thus effectively compensating for uncertainties encountered during a synchronization packet exchange. Due to the deterministic processing time inherent in the FPGA, the proposed synchronization method achieves exceptional precision, with clock offset deviations in the nanosecond range and clock rate deviations limited to only a few parts per billion, even across considerable distances between the network node
CRIS-Team Scopus Importer:2025-01-31
Keywords: Synchronization; Clocks; Time-frequency analysis; Frequency synchronization; Kalman filters; Sensors; Protocols; Frequency estimation; Wireless sensor networks; Real-time systems

Ultra High Speed Wireless Communication: Approaches and Ideas to Achieve Wireless 100 Gb/s Communication (W19) - Low-Power System Architectures for Future 100 Gb/s Wireless Communication Systems - Kissinger, Dietmar; Vossiek, Martin; Berroth, Manfred; Ellinger, Frank (43th European Microwave Week, 2013)
UnivIS-Import:2015-04-16:Pub.2013.tech.IE.LEH.ultrah

Ultra-low-loss interconnection between dielectric and planar transmission line technologies for millimeter-wave applications - Dorbath, Benedikt; Distler, Felix; Schur, Jan; Vossiek, Martin (GeMIC 2020 - Proceedings of the 2020 German Microwave Conference, 2020)
Key future applications, such as multi-gigabit communication, multiple-input multiple-output (MIMO) technologies and networked radars for autonomous driving, require broadband, low loss, lightweight millimeter-wave and THz transmission lines to interconnect circuits, components, modules and systems. Dielectric waveguides (DWG) have proven to be an attractive transmission line option, because they can meet these requirements. Apart from a decent DWG performance, the transition between DWGs and printed circuit boards (PCB) is key to a successful application of DWG technology in particular for monolithic microwave integrated circuit (MMIC) based millimeter-wave systems. In this paper, a waveguide transition between a polarization stable rectangular DWG and a microstrip line (MSL) for W-Band is presented. The design of the waveguide transition aims to minimize the insertion loss considering the constraints of the given manufacturing specifications. A transition with an insertion loss of less than 1.2dB from 82GHz to 94.5GHz is achieved by using an insertion loss simulation model and evaluated by measurements from a fabricated back-to-back transition test setup.
CRIS-Team Scopus Importer:2020-06-02
Keywords: dielectric waveguide; double ridge waveguide; interconnection; microstrip line; waveguide transition

Ultra-Low-Profile Small-Size LTCC Front-End Module (FEM) for WLAN Applications based on a Novel Diplexer Design Approach - Sakhnenko, Sergiy; Orlenko, Denys; Vorotnikov, Borys; Aleksieiev, O.; Komakha, P.; Heide, Patric; Vossiek, Martin (IEEE 2009 International Microwave Symposium (IMS 2009), 2009)
This paper reports on the design of a very compact dual-band highly-integrated front-end module for size-critical wireless applications supporting IEEE 802.11a/b/g standards. The module consists of two novel high-rejection lumped-element diplexers which are connected to one common antenna via single-pole-double-through (SPDT) switch. The novelty of the realized diplexers consists in a new conjugatematching method which allows to design very compact diplexers without additional matching networks. The LTCC integrated diplexers are placed between two ground planes ensuring high electromagnetic compatibility which allows using them as building blocks of the highly-integrated wireless LAN (WLAN) front-end module. The physical dimensions of the complete module are 3.0x3.0x0.95 mm. Up to date this is a smallest LTCC-based switch-diplexer FEM published so far. © 2009 IEEE.
UnivIS-Import:2015-04-16:Pub.2009.tech.IE.LEH.ultral
Keywords: Diplexers; Filters; Front-end module; LTCC; WLAN

Ultraschall-Distanzsensor mit Fuzzy-Auswertung - Kroemer, N.; Vossiek, Martin; Eccardt, P.-C.; Magori, V. (6. Internationale Fachmesse mit Kongress für Sensorik & Systemtechnik, Sensor 93, 1993)
UnivIS-Import:2015-04-16:Pub.1993.tech.IE.LEH.ultras

Ultrasonic defect detection in multi-material, axis-symmetric devices with an improved synthetic aperture focusing technique (SAFT) - Scharrer, Thomas; Koch, Andreas; Fendt, Karl; Rupitsch, Stefan; Sutor, Alexander; Ermert, Helmut; Lerch, Reinhard (2012 IEEE International Ultrasonics Symposium Proceedings, 2012)
This paper describes an improved synthetic-aperture-focusing-technique (SAFT) for ultrasonic defect detection in multi-material devices with a circular cylindrical geometry. In conventional SAFT, defect imaging resolution in such specimen is limited, due to refraction at material interfaces. Hence, the improved technique allows to increase the probability of detection (POD) and the resolution of defects in multi-material, axis-symmetric devices. Especially, if defects are located in layers far away from the device surface and the discrepancies in the speed of sound (SOS) of the specimen materials are thoroughly substantial, it is indispensable to implicate refraction effects in the SAFT processing. Thereby, the examination is divided into three major steps. First, a specimen is scanned by rotating a spherically focused immersion ultrasound transducer around it. In a second step, a corrected time of flight (TOF) distribution is calculated by a fast marching method (FMM) with the à-priori knowledge of the specimen layout and the different SOS in the materials. As third and last step, the improved SAFT is performed utilizing the TOF distribution. To verify improvements in comparison to a conventional SAFT, a specimen is inspected, consisting of a steel and a polyvinyl chloride (PVC) part. © 2012 IEEE.

Ultrasonic imaging of a turbine blade model using a 360° synthetic-aperture-focusing-technique and reverberation suppression - Scharrer, Thomas; Koch, Andreas; Rupitsch, Stefan; Sutor, Alexander; Ermert, Helmut; Lerch, Reinhard (2013 IEEE International Ultrasonics Symposium Proceedings, 2013)
In this contribution, we present a method to complement missing X-ray computed tomography (CT) data of irregular shaped metallic specimen, like turbine blades, by ultrasonic testing in immersion mode. Therefore, an adapted 360° synthetic-aperture-focusing-technique (SAFT) is used to obtain particular information of the inner pattern of the specimen. These structural information cannot be imaged by X-ray CT due to limited penetration in specific directions and consequently absent projections in the dataset. However, arising artifacts caused by refraction and signal reverberation impede the detection of the desired structural information by ultrasonic testing of those irregular metallic specimens. To cope with refraction effects caused by the immense discrepancies in speed of sound (SOS) at the interface of the couplant and the specimen, the approach is based on virtual source elements. Furthermore, the covering of near-surface structures by the first reflection signals is treated by a subspace based filtering approach and signal reverberation artifacts are suppressed by predictive deconvolution. © 2013 IEEE.

Ultrasound-based Eigenfrequency Analysis to Determine Material Parameters of Tissue Mimicking Phantoms - Heim, Christian; Huber, Christian; Ullmann, Ingrid; Lyer, Stefan; Rupitsch, Stefan J. (Current Directions in Biomedical Engineering, 2024)
A modern area of research in cancer treatment is magnetic drug targeting (MDT) with superparamagnetic iron oxide nanoparticles (SPIONs). In order to understand the processes involved in MDT in more detail and to be able to perform this therapy as efficientlyas possible, a monitoring system for thespatialdistribution of SPIONs in biological tissue is required. One approach is to use magnetomotive ultrasound (MMUS) to monitorthe spatial distribution over time. However, the spatial distributionof SPIONs cannot be quantitatively determined applyingbasic MMUS algorithms. Therefore, MMUS has been extended bya simulation part to quantitatively determine the spatial distributionof SPIONs. This extendedMMUS algorithm requires the material parametersand the geometry of the target tumorous tissue. In this contribution,we describe anultrasound-based eigenfrequency analysiscombined with an iterative inverse simulation-based methodto determine the mechanical parameterYoung's modulus oftissue mimicking phantoms.The presentedapproachyields a goodestimate of the Young's modulus compared to the result fromacompression tes
Keywords: Magnetic Drug Targeting; Magnetic Nanoparticles; EigenfrequencyAnalysis; Ultrasonic Sensing; Polyvinyl AlcoholPhantom

Ultrasound-Induced Stable and Inertial Cavitation of Magnetic Nanoparticles for Drug Delivery Applications - Huber, Christian; Hageroth, Lars; Meyer, Constanze; Ermert, Helmut; Ullmann, Ingrid; Vossiek, Martin; Lyer, Stefan (Current Directions in Biomedical Engineering, 2024)
Drug-loaded magnetic nanoparticles (MNPs) ac-cumulated by an external magnetic field already showed theirefficacy in localized tumor treatment in animal studies. Fur-thermore, specific MNPs are sonosensitive, enabling them togenerate inertial cavitation when exposed to a focused ultra-sound field. This can be used for controlling drug release, aswell as for particle detection and mapping. In addition to in-ertial cavitation, stable cavitation is also a part of the cavi-tation process, which has not yet been evaluated on MNPs.While stable cavitation is less harmful to surrounding tissuecompared to inertial cavitation, it also contributes to enhancedtumor perfusion. Hence, an optimal strategy could involve in-ducing inertial cavitation only within the tumor region for drugrelease and mapping, while employing stable cavitation out-side the tumor to enhance perfusion. This study aims to inves-tigate stable cavitation mediated by MNPs for the first time,while examining their overall cavitation behavio

Ultrasound-Mediated Cavitation of Magnetic Nanoparticles for Drug Delivery Applications - Huber, Christian; George, Benedikt; Rupitsch, Stefan Johann; Ermert, Helmut; Ullmann, Ingrid; Vossiek, Martin; Lyer, Stefan (Current Directions in Biomedical Engineering, 2022)
Magnetic nanoparticles guided by an external magnetic field can be used to deliver drugs (e.g., chemotherapeutics) to malignant regions (e.g., tumor tissue). Some nonmagnetic, sonosensitive nanoparticles are known to generate cavitation induced by focused ultrasound. This can can be used to monitor spatial/temporal particle distribution and to stimulate local drug release in target regions. Little to nothing is known about the sonosensitivity of magnetic nanoparticles. Therefore, we investigated this physical phenomenon in the present contribution. We showed that certain magnetic nanoparticles have high cavitation potential and are promising for further research in this regard.
CRIS-Team Scopus Importer:2023-03-08
Keywords: Cavitation; Drug Delivery; Magnetic Nanoparticles; Sonosensitivity; Ultrasound

Ultrasound Phantom of a Carotid Bifurcation Tumor Using Multiple 3D Printed Soluble Filaments - Huber, Christian; Heim, Christian; Ermert, Helmut; Rupitsch, Stefan Johann; Ullmann, Ingrid; Vossiek, Martin; Lyer, Stefan (2024 IEEE International Symposium on Biomedical Imaging (ISBI), 2024)
Accurate models of biological structures are essential for medical training, calibrating equipment, and advancing research without animal experiments. In ultrasound, tissue mimicking phantoms, using materials like agarose or gelatin with added scatterers, are commonly used to simulate biological tissue. While the properties of these phantoms are integral for faithful ultrasound environments, their inner and outer structures are equally crucial. Modifying the outer structure is straightforward with outer molds, but altering the inner structure presents greater challenges. Introducing a tumor structure typically involved using either cylindrical or tethered spherical inclusions, both of which can introduce unwanted reflections. The incorporation of flow systems typically relies on removable rods, limiting complexity. Using 3D printed soluble filament, dissolved in multiple steps, helps to create nearly arbitrary inner structures with different tissue mimicking materials. In this study, the process of generating such complex ultrasound phantoms is described and evaluated with ultrasound measurement

Ultra-Wideband Complex Permittivity Extraction of IC Packaging Materials beyond 100 GHz - Pfahler, Tim; Gold, Gerald; Lomakin, Konstantin; Engel, Lukas; Schür, Jan; Vossiek, Martin (2021 IEEE MTT-S International Microwave Symposium, 2021)
In this work a simple but yet precise permittivity measurement concept is proposed that is especially suited for broadband characterization of IC packaging material beyond 100 GHz. The novel concept is based on the evaluation of the propagation coefficient of the TE 10 -mode of a rectangular waveguide with the use of an advanced analytic transmission line model. To eliminate parasitic conductor effects as the bulk conductivity and surface roughness of the waveguide walls, two measurements are carried out: One measurement with an air-filled waveguide and one measurement where the waveguide is filled with the material under test. With these two measurements and by applying the analytic transmission line model, the parasitic distortions can be eliminated. The approach enables ultra-wideband permittivity determination and is not limited to a specific frequency range. The complex permittivity of an investigated packaging material could almost continuously be extracted from 110 GHz up to 320 GHz. The method is experimentally verified on the basis of material samples with material parameters given in literature.
Keywords: Permittivity measurement; Resonant frequency; Packaging; Conductivity measurement; Transmission line measurements; Data models; Surface roughness; complex permittivity; material characterization; packaging material; surface roughness; transmission line model

Ultra Wideband Power Detector for W-Band Applications Using a Novel Additively Manufactured Wave Mode Transducer - Bader, Tobias; Lomakin, Konstantin; Gold, Gerald (2023 IEEE Wireless and Microwave Technology Conference, WAMICON 2023, 2023)
Keywords: additive manufacturing; transition; power detector; wavemode transducer

Ultra-Wideband Radio Technologies for Communications, Localization and Sensor Applications - Eßwein, Alexander; Carlowitz, Christian; Weigel, Robert; Vossiek, Martin (Ultra-Wideband Radio Technologies for Communications, Localization and Sensor Applications, 2013)
UnivIS-Import:2015-04-20:Pub.2013.tech.IE.LEH.ultraw

Unobtrusive Gait Reconstructions using Radar-based Optimal Control Simulations - Gambietz, Markus; Dröge, Anne; Schüßler, Christian; Stahlke, Maximilian; Wirth, Vanessa; Miehling, Jörg; Koelewijn, Anne (Asilomar Conference on Signals, Systems, and Computers, 2024)

Untersuchungen ueber die Eignung der 2, 45-GHz-Mikrowellenerwärmung fuer eine endoskopische Koagulationstherapie - Bodem, F; Reidenbach, H; Nehls, M; Brand, Hans; Fruehmorgen, P (Biomedizinische Technik, 1975)
lhft_intern.bib::thirty_years_LHFT_27

Untersuchungen zur Eignung heißgeprägter Folien für die Integration von Antennen in Automotive-Exterieurbauteile - Fuchs, Michael; Drummer, Dietmar; Kilian, Andreas; Schmidt, Lorenz-Peter (Zeitschrift Kunststofftechnik, 2009)
UnivIS-Import:2015-03-09:Pub.2009.tech.FT.FT-KT.unters

Untersuchungen zur Energieversorgung Eines Systems zur Drahtlosen Datenübertragung für Anwendungen in der Medizin - Kirsch, Fabian; Wittwer, J. (2008)

Untersuchungen zur Energieversorgung eines Systems zur drahtlosen Datenübertragung für Anwendungen in der Medizin - Wittwer, J.; Kirsch, Fabian; Vossiek, Martin (Sensoren und Messsysteme 2008, 2008)
UnivIS-Import:2015-04-16:Pub.2008.tech.IE.LEH.unters

Untersuchungen zur Strahlungsbelastung eines Beobachters beim BSD-2000-Hyperthermiesystem - Schaller, G; Engelbrecht, Rainer; Erb, J (1994)
lhft_intern.bib::thirty_years_LHFT_337

Untersuchungen zur Strahlungsbelastung eines Beobachters beim BSD-2000-Hyperthermiesystem - Schaller, Gerhard; Engelbrecht, Rainer; Erb, J. (25. Wissenschaftliche Tagung der Deutschen Gesellschaft für Medizinische Physik (DGMP), 1994)
UnivIS-Import:2015-04-16:Pub.1994.tech.IE.LEH.unters

Unzoned and zoned dielectric lenses for a wide angle scanning antennna - Schmidt, Lorenz-Peter (MIOP `88, 1988)
lhft_intern.bib::Schmidt17

Use of Fiber Nonlinearities for Signal Improvement in Optical Transmission Systems - Schmauß, Bernhard; Holtmannspötter, Michael; Stephan, Christian; Sponsel, Klaus; Onishchukov, Georgy; Leuchs, Gerd (Frequenz, 2009)
UnivIS-Import:2015-03-09:Pub.2009.nat.dphy.optik.1optik.useoff

Using coherent optical frequency domain reflectometry to assist the additive manufacturing process of structures for radio frequency applications - Köppel, Max; Deckelmann, M; Sippel, Mark; Lomakin, Konstantin; Werzinger, Stefan; Gold, Gerald; Helmreich, Klaus; Schmauß, Bernhard (SPIE Optics + Photonics: Optical Engineering + Applications, 2018)

Using Group Velocity for Correct Determination of Phase Coefficient Without Initial Phase Assumption - Lomakin, Konstantin; Helmreich, Klaus; Gold, Gerald (2020 IEEE 24th Workshop on Signal and Power Integrity (SPI), 2020)
In this paper, an approach is proposed that allows to measure the absolute quantity of guided wavelength and phase coefficient of arbitrary transmission line types. By using the group velocity as a derivative quantity of the phase coefficient, ambiguities within the logarithm of complex values can be resolved. The typically unknown initial phase coefficient offset of band limited measurements can be acquired by the proposed approach without the need for assumptions concerning the transmission line type and acquisition of its explicit cross section geometr

Using saturation effects in a nonlinear amplifying loop mirror for multilevel phase-preserving amplitude regeneration - Roethlingshoefer, Tobias; Onishchukov, Georgy; Schmauß, Bernhard; Leuchs, Gerd (Transparent Optical Networks (ICTON), 2011 13th International Conference on, 2011)
The influence of amplifier gain saturation in nonlinear amplifying loop mirror on simultaneous phase-preserving regeneration of two power states has been studied. Numeri cal simulations have shown an improvement of up to 4 dB for the first, low-power state and 8 dB for the se cond high-power state. Compar ed to the linear amplifier case an improvement of 3 dB for the se cond power state has been achieved.
lhft_intern.bib::Roethlingshoefer2011a
Keywords: 2R regeneration; quadrature amplitude modulation; NALM; NOLM

Validating sweat ammonia as physiological parameter for wearable devices in sports science - Renner, Esther; Lang, Nadine; Langenstein, Bernd; Struck, Matthias; Bertsch, Thomas (Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS, 2020)
The measurement of physiological parameters in sweat has long been assumed to offer a non-invasive alternative to conventional blood testing. Recently, advances in sensor technology enable the production of printed sweat sensors applicable for the use in wearable devices. However, the remaining challenge is the determination of the physiological correlation between blood and sweat components. In this study, we conducted ammonia measurements in blood and sweat during a stepwise incremental cycle ergometer test in 40 subjects under completely controlled conditions in a clinical environment to determine the correlation between the ammonium concentrations in blood and sweat. Samples were taken for each workload step separately. Sweat was sampled directly from the upper body, blood was taken from an indwelling cannula at the end of each workload step, respectively. For meaningful classification of the measured quantities, blood lactate and heart rate were monitored additionally. The results for blood ammonium concentration show increasing behavior in good accordance with the established indicators for physical exhaustion, whereas sweat ammonium concentration seems to decrease with workload. This is found to be due to dilution, as sweat rate increases. The presented results provide insight in the correlation between blood and sweat parameters and therefore are of high importance for further development of wearable devices.Clinical Relevance - Sweat sensing opens up new possibilities for non-invasive, continuous in-situ monitoring of physiological parameters for healthcare and sports science applications.
CRIS-Team Scopus Importer:2020-09-25