Comparison of Modulation Schemes for 10.7 Gb/s Transmission Over Large-Core 1 mm PMMA Polymer Optical Fiber - Loquai, Sven; Kruglov, Roman; Schmauß, Bernhard; Bunge, C. -A.; Winkler, Florian; Ziemann, Olaf; Hartl, Engelbert; Kupfer, Theodor (Journal of Lightwave Technology, 2013)
The authors give an overview of experimental results on 10.7 Gb/s over large-core 1 mm polymethyl-methacrylate (PMMA) polymer optical fiber (POF). The comparison starts with simple non-return-to-zero (NRZ) transmission without equalization. Next, measurement results with feed-forward-, decision-feedback equalization (FFE, DFE) and maximum likelihood sequence estimation (MLSE) are presented. Finally, experimental results with more advanced modulation schemes like pulse amplitude modulation (PAM) and discrete multitone (DMT) modulation are investigated. The experiments were carried out with a Vertical-Cavity Surface-Emitting Laser (VCSEL) at 0 dBm to comply with consumer eye-safety regulation or with a 10 mW laser diode (LD) that could be used in active optical cables. © 1983-2012 IEE
UnivIS-Import:2015-03-09:Pub.2013.tech.IE.LEH.compar
Keywords: Discrete multitone modulation; feed-forward and decision-feedback equalization; maximum likelihood sequence estimation; non-return-to-zero modulation; optical communication; polymer optical fiber; pulse amplitude modulation

Comparison of noise effects in derivate and direct absorption TDLAS - A simulation based approach - Lins, Bastian; Engelbrecht, Rainer; Schmauß, Bernhard; et al. (TDLS - 7th International Conference on Tuneable Diode Laser Spectroscopy, 13.-17.07.09, Zermatt, Schweiz, 2009)
UnivIS-Import:2015-04-16:Pub.2009.tech.IE.LEH.compar

Comparison of Phase-Based 3D Near-Field Source Localization Techniques for UHF RFID - Parr, Andreas; Miesen, Robert; Vossiek, Martin (Sensors, 2016)
lhft_intern.bib::Parr2016a

Compensation of linear and nonlinear signal distortion by optimized digital backward propagation - Lin, Chien-Yu; Asif, Rameez; Holtmannspötter, Michael; Schmauß, Bernhard (Photonische Netze - 13. ITG-Fachtagung, 2020)
We present results of nonlinear compensation achieved by digital backward-propagation (DBP) for next-generation optical coherent transmission systems. In our numerical investigations, phase-encoded signals (DQPSK) as well as signals of higher-order modulation formats (16-QAM) have been analyzed with respect to degradation by fiber nonlinearity such as self-phase modulation (SPM). The influence of inline compensation schemes used is studied and we also showed that DBP performance depends strongly on its parameters. A careful adjustment of e.g. the nonlinear calculating position improves the eye opening up to 3.5dB for DQPSK signals. Our work also includes investigations on optimized step-size selection. The implementation of a logarithmic step-size distribution reduces the numerical effort by about 50% with respect to using constant step-size distributions in 112Gbps 16-QAM transmission. Furthermore, by using an additional low-pass-filter (LPF) in each DBP stage, the required number of DBP stages is significantly reduced, where the computational efficiency can be enhanced without significant loss of performance, which will be helpful in future deployment of DBP in real-time signal processing modules for non-linear compensation. In order to explore the capability of this filtered DBP in terms of complexity, the results of diverse baud rates for multiple channel DP-QPSK systems with a total transmission capacity of 1.12 Tbit/s are compared.
CRIS-Team Scopus Importer:2021-04-19

Compensation of Nonlinear Phase Noise Using the Effective Negative Nonlinearity of a Nonlinear Amplifying Loop Mirror - Sponsel, Klaus; Stephan, Christian; Onishchukov, Georgy; Schmauß, Bernhard; Leuchs, Gerd (IEEE Journal of Selected Topics in Quantum Electronics, 2012)
The nonlinear amplifying loop mirror (NALM) has been explored for use as a nonlinear phase-shift compensator (NPSC). Operation conditions for a tunable effective negative nonlinearity are considered and the NALM parameter optimization is discussed for direct bit-error-ratio (BER) improvement by postcompensation after a nonlinear transmission line. In this configuration, the fundamental limits for NPSC are estimated for differential quadrature phase-shift keying (DQPSK) using a simplified model. Numerical simulations of a 20 Gb/s RZ-DQPSK transmission system confirmed the applicability of this model and showed a significant BER improvement in a realistic transmission line. Alternatively, the fiber launch power per span could be increased by 2 dB for the same BE
lhft_intern.bib::Sponsel2012

Compensation of Signal Distortion by Optimized Digital Backward Propagation in DQPSK transmission - Lin, Chien-Yu; Holtmannspötter, Michael; Asif, Rameez; Schmauß, Bernhard (IEEE Photonics Technology Letters, 2011)
We optimize digital backward-propagation (DBP) to compensate signal distortions for various launch powers and bit rates. By optimizing transmission parameters and nonlinear phase calculating point, multi-span DBP gives significant improvement.
UnivIS-Import:2015-03-09:Pub.2010.tech.IE.LEH.compen_6

Compensation of Transmission Impairments by Digital Backward Propagation for Different Link Designs - Lin, C.; Holtmannspoetter, M.; Asif, M. R.; Schmauß, Bernhard (36th European Conference and Exhibition on Optical Communication (ECOC), 2010)
lhft_intern.bib::Lin10b

Complete Characterization of Coaxial Microwave Antennas Used for Interstitial Hyperthermia - Theory and Experiment - Erb, J; Engelbrecht, Rainer; Schaller, G; Seegenschmiedt, H; Sauer, R (1994)
lhft_intern.bib::thirty_years_LHFT_347

Complete Characterization of Coaxial Microwave Antennas Used for Interstitial Hyperthermia - Theory and Experiment - Erb, J.; Engelbrecht, Rainer; Schaller, Gerhard; Seegenschmiedt, Heinrich; Sauer, R. (Joint Meeting of Europ. Soc. for Radiation Biology (ESRB) and Hyperthermia Oncology (ESHO), 1994)
UnivIS-Import:2015-04-16:Pub.1994.tech.IE.LEH.comple

Complex Permittivity Extraction of IC-Package Materials beyond 110 GHz by Band-Limited Waveguide-Cavity Measurements - Pfahler, Tim; Gold, Gerald; Bachbauer, Felix; Schür, Jan; Vossiek, Martin (2023 53rd European Microwave Conference, EuMC 2023, 2023)
In this work, an accurate method for extracting the frequency-dependent complex permittivity in frequency bands above 110 GHz using a resonant waveguide (WG) cavity is presented. Although the measurement information is band-limited and the first TE-mode cannot be measured, the method can dispense with this information in a two-stage measurement procedure. The information from a prior non-resonant, but still band-limited, measurement is used to assign resonance peaks occurring in the resonant measurement to the corresponding resonance modes. This enables the correct mapping of the respective TE-modes from the air-filled to MUT-filled WG cavity across different frequency bands, and subsequently extracting the complex permittivity from their comparison. To ensure distortion-free determination of the complex permittivity at multiple frequency points throughout the frequency band, the influence of WG cavity coupling on the determination of the resonant frequency and quality factor (Q) is compensated.
CRIS-Team Scopus Importer:2023-12-01
Keywords: cavity resonator; complex permittivity; coupling compensation; IC-packaging; material characterization; Q-factor; resonant-perturbation method

Complex Permittivity Measurements of Curing Epoxy Resin in Glass Fibre Reinforced Composite - Groh, Jannis; Lipka, Melanie; Schür, Jan; Vossiek, Martin (46th European Microwave Conference, 2017)

Compression of Preprocessed Automotive Radar Data by Using Context-Adaptive Binary Arithmetic Coding - Rückert, Rainer; Li, Yanyan; Herglotz, Christian; Sura, Oliver; Kaup, André; Vossiek, Martin (2024 21st European Radar Conference (EuRAD), 2024)

Compressive and tensile strain sensing using a polymer planar Bragg grating - Rosenberger, M.; Hessler, S.; Belle, S.; Schmauß, Bernhard; Hellmann, R. (Optics Express, 2014)
A polymer planar Bragg grating sensor is used for measuring both mechanical compressive and tensile strain. The planar waveguide with integrated Bragg grating is fabricated in bulk Polymethylmethacrylate in a single writing step using combined amplitude and phase mask technique. After butt coupling of a single-mode optical fiber the planar structure can be applied for measuring both mechanical tensile and compressive strain alongside the integrated waveguide without the need of further modifications. In this respect, we particularly report for the first time compressive strain measurements using a polymer Bragg grating. Furthermore, the sensitivity of the sensor against tensile and compressive strain, its reproducibility and hysteresis are investigated and discusse
lhft_intern.bib::Rosenberger2014b

Concept and Implementation of a PLL-Controlled Interlaced Chirp Sequence Radar for Optimized Range-Doppler Measurements - Thurn, Karsten; Shmakov, Denys; Li, Gang; Max, Stephan; Meinecke, Marc-Michael; Vossiek, Martin (IEEE Transactions on Microwave Theory and Techniques, 2016)
In this paper, we introduce a novel concept for frequency-modulated continuous-wave radar. The approach is based on an interlaced chirp sequence waveform, which is controlled by phase-locked loops (PLLs). The use of PLLs improves frequency chirp linearity and reduces phase noise compared with open-loop voltage-controlled oscillators commonly used to generate the fast chirps. In contrast to basic range-Doppler processing, it enables higher target velocities to be detected unambiguously at the same resolution, which makes it suitable for automotive applications. Separate frequency synthesizers generate the interlaced ramps in the system. An RF switch combines these two signals to suppress transients caused by oscillator overshoot and to avoid incoherencies due to programming times of the PLL ICs. We built a prototype radar system in K-band. The test results are promising and bode well for other applications.
Keywords: Frequency modulation; phase-locked loops (PLLs); radar; radar signal processing; remote sensing; Signal synthesis.

Concept for an Automatic Annotation of Automotive Radar Data Using AI-segmented Aerial Camera Images - Hoffmann, Marcel; Braun, Sandro; Sura, Oliver; Stelzig, Michael; Schüßler, Christian; Graichen, Knut; Vossiek, Martin (Proceedings of the IEEE Radar Conference, 2023)
This paper presents an approach to automatically annotate automotive radar data with AI-segmented aerial camera images. For this, the images of an unmanned aerial vehicle (UAV) above a radar vehicle are panoptically segmented and mapped in the ground plane onto the radar images. The detected instances and segments in the camera image can then be applied directly as labels for the radar data. Owing to the advantageous bird's eye position, the UAV camera does not suffer from optical occlusion and is capable of creating annotations within the complete field of view of the radar. The effectiveness and scalability are demonstrated in measurements, where 589 pedestrians in the radar data were automatically labeled within 2 minutes.
Created from Fastlane, Scopus look-up
Keywords: Automotive radar; data annotation; image segmentation; machine learning; sensor fusion

Concept for a Novel Low-Complexity QAM Transceiver Architecture Suitablefor Close to Transition Frequency Operation - Carlowitz, Christian; Vossiek, Martin (IEEE MTT-S International Microwave Symposium, IMS 2015, 2015)
The implementation of ultra-high speed mm-wave and THz transceivers based on homodyne concepts suffers from severe scaling issues with respect to system complexity, circuit size and power consumption as such transceivers nowadays typically need to operate close to the transition frequency of the underlying semiconductor process. In order to mitigate these severe issues, we propose a novel regenerative sampling concept based on a simple positive feedback low-gain amplifier stage. We show for the first time a concept that allows to regenerate quadrature modulated signals with minimal effort based on a simultaneous phase and amplitude regenerative sampling (SPARS) process. This concept enables attractive alternatives to the homodyne approach, e.g., a synthesizer-free self-mixing receiver, which significantly reduces the complexity of the receiver circuit. This paper provides the proof-of-concept of the novel approach by simulations and by measurements with a lumped element 22 GHz 16-QAM feasibility demonstrator.
lhft_intern.bib::Carlowitz2015
Keywords: frequency synthesis; front-end circuits and systems; microwave and mm-wave oscillators; transceiver architectures

Concept for Automatic Annotation of Automotive Radar Data Using AI-Segmented Camera and Lidar Reference Data - Heidbrink, Max; Sura, Oliver; Rangaraj, Vinoth Kumar; Reinecke, Marc; Hoffmann, Marcel; Vossiek, Martin (2024 21st European Radar Conference (EuRAD), 2024)
This work presents a concept for automatic annotation of automotive radar data by combining AI-segmented camera images and 3D lidar point clouds. The AI-interpreted images are used to detect objects or features, which are then localized within the lidar point cloud. This enables a precise labeling of various radar data representations. The concept’s effectiveness is validated on a test vehicle equipped with an automotive radar and off-the-shelf camera and lidar sensors. As this concept relies on standard processing techniques, it integrates seamlessly into other setups and is beneficial along the complete radar development chai

Concept for Raman Distributed Temperature Sensing in Optical Fibers based on Standard C-Band Spectrometer - Renner, Esther; Härteis, Lisa-Sophie; Scheffter, Kilian; Schmauß, Bernhard (Optics InfoBase Conference Papers, 2022)
We propose a concept for Raman distributed temperature sensing based on L-band excitation and C-band Anti-Stokes detection. The concept is demonstrated by interrogation of 1500 m fiber with incoherent optical frequency domain reflectometry.
Created from Fastlane, Scopus look-up

Concepts and Components for Pulsed Angle Modulated Ultra Wideband Communication and Radar Systems - Eßwein, Alexander; Weigel, Robert; Carlowitz, Christian; Vossiek, Martin (Intech, 2013)
Ultra-Wideband Radio (UWB) earmarks a new radio access philosophy and exploits several GHz of bandwidth. It promises high data rate communication over short distances as well as innovative radar sensing and localization applications with unprecedented resolution. Fields of application may be found, among others, in industry, civil engineering, surveillance and exploration, for security and safety measures, and even for medicine. The book considers the basics and algorithms as well as hardware and application issues in the field of UWB radio technology for communications, localization and sensing based on the outcome of DFG's priority-funding program "Ultra-Wideband Radio Technologies for Communications, Localization and Sensor Applications (UKoLoS)".
elib2cris::1512001600,esswein2013
Keywords: Ultra Wideband

Concepts for Generation of Angle Modulated mm-Wave UWB Signals for Communication and Ranging - Carlowitz, Christian; Eßwein, Alexander; Weigel, Robert; Vossiek, Martin (IMS 2013 Workshop on RFICs/MMICs and Their Professional Wireless Sensing Applications, 2013)
UnivIS-Import:2015-04-16:Pub.2013.tech.IE.LEH.concep

Conformal Superstrate Loaded Automotive Radar Antenna for Integration in Polymer Car Body Panels - Kilian, Andreas; Schmidt, Lorenz-Peter (Antennas and Propagation (EuCAP), 2010 Proceedings of the Fourth European Conference on, 2010)
In this contribution the design process for hot embossed millimeter-wave antennas integrated in plastic multilayer car body panels is presented. Starting from material characteristics and fixed parameters obtained by the investigation of the fabrication process steps, the design of a microstrip patch antenna working at 24GHz will be demonstrated. The antenna is embedded within a plastic multi-layer structure by laminating the substrate layer with a paint foil and reinforcing the part by back injection molding. The comparison between simulation and measurement results will give information about the producibility of conformal integrated antennas for automotive radar applications like pre-crash detection or parking aid.
lhft_intern.bib::Kilian10a

Considerations for Future Automotive Radar in the Frequency Range Above 100 GHz - Köhler, Aaron; Gumbmann, Frank; Schür, Jan; Schmidt, Lorenz-Peter; Bloecher, H.-J. (RoCC-Session , GeMiC 2010, Berlin, 2010)
Within the last years automotive radar sensors became more and more important. Started with comfort systems like adaptive cruise control (ACC) and parking aid, the safety aspect increasingly came to the fore. In the near future not only upper class cars will be equipped with various radar applications like pre crash, collision warning and collision avoidance to increase traffic safety. Therefore many high performance radar sensors have to be integrated in the car. This paper describes the demands on future radar sensors. It is discussed how the step to higher operating frequencies could be beneficial particularly for urban situations with high traffic density. Furthermore the paper will provide and discuss design considerations for future mmW-Radar sensors in automotive safety applications.
lhft_intern.bib::Koehler10

Considerations for V- and W-Band Inter-Satellite Links - Maune, Holger; Hübner, Karl-Heinz; Gold, Gerald (22nd IEEE Wireless and Microwave Technology Conference (WAMICON), 2022)

Constellation Estimation, Coherent Signal Processing, and Multiperspective Imaging in an Uncoupled Bistatic Cooperative Radar Network - Fenske, Patrick; Kögel, Tobias; Ghasemi, Roghayeh; Vossiek, Martin (IEEE Journal of Microwaves, 2024)
Cooperative radar networks are a promising technology in various areas, such as vehicle-to-infrastructure networks for automotive radar and radar remote sensing with UAVs. The use of widely distributed radar networks enables the detection of targets with complex scattering characteristics, as their coherent bistatic images are superior for forward scattering, and each monostatic image illuminates a scene from a different perspective. This work introduces a signal processing scheme that addresses two main challenges in this area: the coherent signal processing of uncoupled radar nodes and the self-localization of the nodes for radar image combination. A comprehensive signal model that incorporates time, frequency and phase incoherency is introduced. Based on this, an algorithm for constellation estimation, synchronization up to the carrier phase level, and multiperspective imaging is developed. The proposed approach is experimentally verified using commercially available 77GHz single-input/multiple-output radar nodes. The measurements for different radar constellations and various target scenes show a self-localization accuracy below 6cm in range and below 2.5∘ for the incident angles. The resulting images of various scenes clearly indicate an information gain compared to single monostatic images due to the combination of bistatic and multiperspective monostatic images.<br
Keywords: Radar; Radar imaging; Phase noise; Radar antennas; Chirp; Time-frequency analysis; Synchronization; Bistatic radar; chirp sequence modulation; cooperative radar networks; FMCW; localization; millimeter-wave radar; multiperspective imaging; radar networks; synchronization

Contactless Inspection of Handwritten Documents with Terahertz Imaging - Ullmann, Ingrid; Root, Konstantin; Schür, Jan; Scheuble, Lorenz; Vossiek, Martin (18th European Radar Conference (EuRAD 2021), 2022)
This paper presents results of studies on the use of Terahertz (THz) imaging for contactless inspection of handwritten and possibly sealed documents as a preliminary study for the THz-based inspection of historical documents. We investigated the use of focused B-scans in transmission mode. As a basis, some general aspects associated with the investigated scenario are presented. These include investigations of paper and ink as well as the system’s image resolution. For possible application in scanning historical letters, one and stacks of two papers with handwriting inside an envelope were investigated. <

Continuous People Crowd Monitoring defined as a Regression Problem using Radar Networks - Guendel, Ronny G.; Ullmann, Ingrid; Fioranelli, Francesco; Yarovoy, Alexander (European Radar Conference, 2023)
Radar-based human activity recognition in crowded environments using regression approaches is addressed. Whereas previous research has focused on single activities and subjects, the problem of continuous activity recognition involving up to five individuals moving in arbitrary directions in an indoor area is introduced. To treat the problem, a regression-based approach is used, which offers innovative insights into creating robust and accurate systems for monitoring human activities. Novel approaches utilizing LSTM or CNN regression techniques with Linear Regression and Support Vector Machine regressor are compared on extracted features from radar data through the Histogram of Oriented Gradients and Principal Component Analysis. These approaches are rigorously evaluated by a Leave-One-Group-Out method, with performance assessed using common regression metrics such as the RMSE. The most promising outcomes were observed for crowds of three and five individuals, with respective RMSE of approximately 0.4 and 0.6. These results were primarily achieved by utilizing the micro-Doppler (µD) Spectrogram or range-Doppler data domai

Contributions of Time-of-Flight cameras for biomedical applications - Höller, Kurt Emmerich; Schaller, Christian; Tacke, Dominik; Höpfl, Florian; Hornegger, Joachim (Innovationen bei der Erfassung und Analyse bioelektrischer und biomagnetischer Signale, 2008)

Convolutional Neural Network Assisted Detection and Localization of UAVs with a Narrowband Multi-site Radar - Martinez, Javier; Kopyto, David; Schütz, Martin; Vossiek, Martin (IEEE MTT-S International Conference on Microwaves for Intelligent Mobility (ICMIM 2018), 2018)
We present an approach to detect and locate non-cooperative UAVs from their micro-Doppler signature using a narrowband radar in a multi-site configuration. We describe a method for the localization of rotating objects with the geometric information obtained exclusively from their micro-Doppler signatures. This approach only requires very simple transceivers with CW waveforms, in a cost-effective multi-site architecture. A convolutional neural network is used to detect and identify the UAVs by extracting the characteristic features of their micro-Doppler signature. We present simulated and preliminary experimental data that show the technical viability of this concep
lhft_intern.bib::Martinez18a

Convolutional Neural Network Classification of Vulnerable Road Users based on Micro-Doppler Signatures using an Automotive Radar - Wachtel, Diogo; Edler, Johannes; Schroder, Sabine; Queiroz, Samuel; Huber, Werner (IEEE Conference on Intelligent Transportation Systems, Proceedings, ITSC, 2022)
Advanced driver assistance systems (ADAS) are growing in quantity and complexity, requiring even more sensor effectiveness and computational resources. Even though cameras and LiDAR sensors can provide a steady solution in ideal conditions, they are unreliable for adverse weather conditions, such as rain and dense fog. Therefore, radar technology is used for those circumstances is an option to be used for those circumstances. However, its classification accuracy must be enhanced to compete with the other sensor types. This work presents a solution to enhance radar classification quality, adapting a Convolutional Neural Network (CNN) structure to the input of micro-Doppler images of vulnerable road users (VRUs), such as pedestrians, cyclists, and e-scooter drivers. Moreover, two CNNs were trained, each for a particular region of interest (ROIs), one in the near field of the radar until 15m, and the second one up to 25m. The proposed solution presents a promising overall accuracy for its first trial. Nevertheless, it must be further extended to more complex scenes, including more participants, obstacles, and weather conditions.
CRIS-Team Scopus Importer:2022-11-25
Keywords: convolutional neural networks; object classification; radar applications

Convolutional neural networks for parking space detection in downfire urban radar - Martinez Garcia, Javier; Zoeke, Dominik; Vossiek, Martin (International Journal of Microwave and Wireless Technologies, 2018)
We present a method for detecting parking spaces in radar images based on convolutional neural networks (CNN). A multiple-input multiple-output radar is used to render a slant-range image of the parking scenario and a background estimation technique is applied to reduce the impact of dynamic interference from the surroundings by separating the static background from moving objects in the scene. A CNN architecture, that also incorporates mechanisms to generalize the model to new scenarios, is proposed to determine the occupancy of the parking spaces in the static radar images. The experimental results show very high accuracy even in scenarios where little or no training data is available, proving the viability of the proposed approach for its implementation at large scale with reduced deployment effort
lhft_intern.bib::Martinez18c

Cooperative Indoor Localization Using 24-GHz CMOS Radar Transceivers - Ebelt, Randolf; Hamidian, Amin; Shmakov, Denys; Zhang, Tao; Subramanian, Viswanathan; Boeck, Georg; Vossiek, Martin (IEEE Transactions on Microwave Theory and Techniques, 2014)
This paper presents the first truly wireless 24-GHz round-trip time-of-flight local positioning frontend with an integrated CMOS transceiver. The transceiver in 130-nm CMOS technology features a novel receiver/transceiver switching concept, which reduces RF losses between the receiver/transmitter and antenna and drastically improves the transmit/receive isolation. The low-power RF transceiver chip was integrated with a digital signal-processing unit and mounted on a circuit board to form a system-level demonstrator of a secondary radar node incorporating synchronization and a distributed localization algorithm. The performance of the self-organizing localization network is evaluated in an indoor setup using comparisons with reference trajectories. Experimental results show a distance precision between the active nodes close to the theoretical optimum that can be achieved with the used signal parameters, as well as an absolute localization error in the centimeter rang
lhft_intern.bib::Ebelt2014a

Corrections to "Design and Fabrication of Broadband Hybrid GaAs Schottky Diode Frequency Multipliers" - Hrobak, Michael; Sterns, Michael; Schramm, Markus; Stein, Wadim; Schmidt, Lorenz-Peter (IEEE Transactions on Microwave Theory and Techniques, 2015)
The block diagram shown in Fig 33 of the above-named paper [ibid., vol. 61, no. 12, pp. 4442–4460, Dec. 2013] is incorrect. Instead of series resonators, it should contain parallel resonators. A corrected version is provided here as Fig. 1. In the continuous text of the above paper [p. 4451, col. 2, line 38] it reads "MSL half-wave series resonator," which is incorrect. It should read "half-wave MSL parallel resonator
lhft_intern.bib::Hrobak2015

Cost-effective multi-camera array for high quality video with very high dynamic range - Keinert, Joachim; Wetzel, Marcus; Schöberl, Michael; Schäfer, Peter; Zilly, Frederik; Bätz, Michel; Foessel, Siegfried; Kaup, André (Digital Photography X, 2014)
Temporal bracketing can create images with higher dynamic range than the underlying sensor. Unfortunately, moving objects cause disturbing artifacts. Moreover, the combination with high frame rates is almost unachievâ-able since a single video frame requires multiple sensor readouts. The combination of multiple synchronized side-by-side cameras equipped with different attenuation filters promises a remedy, since all exposures can be performed at the same time with the same duration using the playout video frame rate. However, a disparity correction is needed to compensate the spatial displacement of the cameras. Unfortunately, the requirements for a high quality disparity correction contradict the goal to increase dynamic range. When using two cameras, disparity correction needs objects to be properly exposed in both cameras. In contrast, a dynamic range inâ-crease needs the cameras to capture different luminance ranges. As this contradiction has not been addressed in literature so far, this paper proposes a novel solution based on a three camera setup. It enables accurate deâ-termination of the disparities and an increase of the dynamic range by nearly a factor of two while still limiting costs. Compared to a two camera solution, the mean opinion score (MOS) is improved by 13.47 units in average for the Middleburry images. © 2014 SPIE-IS and
Keywords: camera array; correlation; disparity correction; ghosting artifacts; High dynamic range; occlusions

Cost-minimized 24 GHz pulse oscillator for short-range automotive radar applications - Kryshtopin, Andriy; Sevskiy, Georgiy; Markov, Konstyantyn; Heide, Patric; Nalezinski, Martin; Roskosch, R.; Vossiek, Martin (33rd European Microwave Conference, EuMC, 2003)
This paper reports on the design of ultra-wideband 24 GHz pulse oscillators developed for automotive radar applications. Due to system considerations (range resolution, dynamic range), such oscillator modules need to generate ultra-short coherent pulses. Measurement results of prototype oscillators demonstrate +5 dBm peak output power, less than 1 ns pulse width and excellent coherency. The oscillators were applied in a radar sensor and good performance was achieved. © 2003 EUMA.
UnivIS-Import:2015-04-16:Pub.2003.tech.IE.LEH.costmi

Creation of an Electro-magnetic Heat Simulation for Planning Hyperthermia Treatments for Mice - Kahlert, B.; Bert, Christoph; Rückert, Michael; Hensel, Bernhard; Root, Konstantin; Vossiek, Martin; Fietkau, Rainer; Gaipl, Udo; Frey, Benjamin (STRAHLENTHERAPIE UND ONKOLOGIE, 2022)
CRIS-Team WoS Importer:2022-06-03

Critical review of the gain factor of 16 for calculation of the Raman threshold in fibers - Engelbrecht, Rainer (Conference on Lasers and Electrooptics (CLEO:2015), 2015)
Analytic approximations yielding the well-known gain factor of 16 in formulas for SRS threshold in fibers are compared to rigorous simulations. This factor is shown to be larger for short and modern fibers, as used for high-power lasers.
lhft_intern.bib::engelbrecht15b

Cross-Modal Supervision-Based Multitask Learning with Automotive Radar Raw Data - Jin, Yi; Deligiannis, Anastasios; Fuentes-Michel, Juan Carlos; Vossiek, Martin (IEEE Transactions on Intelligent Vehicles, 2023)
With the rapid development of autonomous driving technology, radar sensors play a vital role in the perception system due to their robustness under harsh environmental conditions, exact range and velocity perception capability. However, the state-of-the-art performance of algorithms solely based on radar to achieve various perception tasks, such as classifying road users and infrastructures, still lags far behind expectation. Their failure can mainly be accounted for the extreme sparseness of radar point cloud for objects, low angular resolution, and the issue of ghost targets. In this work, we propose a novel network that employs the complex range-Doppler matrix as input to achieve radar-tailored panoptic segmentation (i.e., free-space segmentation and object detection ). Our network surpasses previous works in free-space segmentation and object detection tasks, and the improvement in the former task is especially notable. During training, the segmented camera image with radar customized adaption is utilized as the ground truth. Through such a cross-modal supervision method, the labeling expense is alleviated considerably. Based on it, we further design an innovative camera-radar system concept that is able to automatically train deep neural networks with radar measurement.<br

Cross-Modal Supervision Based Road Segmentation and Trajectory Prediction with Automotive Radar - Wang, Zhaoze; Jin, Yi; Deligiannis, Anastasios; Fuentes-Michel, Juan-Carlos; Vossiek, Martin (IEEE Robotics and Automation Letters, 2024)
Automotive radar plays a crucial role in providing reliable environmental perception for autonomous driving, particularly in challenging conditions such as high speeds and bad weather. In this domain the deep learning-based method is one of the most promising approaches, but the presence of noisy signals and the complexity of data annotation limit its development. In this paper, we propose a novel approach to address road area segmentation and driving trajectory prediction tasks by introducing Differential Global Positioning System (DGPS) data to generate labels in a cross-modal supervised manner. Then our method employs a multi-task learning-based CNN trained by radar point clouds or occupancy grid maps without any manual modification. This multi-task network not only boosts processing efficiency but also enhances the performances in both tasks, compared with single-task counterparts. Experimental results on a real-world dataset demonstrate the effect of our implementation qualitatively, achieving decimeter-level predictions within a 100 m forward range. Our approach attains an impressive 91.4 % mean Intersection over Union (mIoU) in road area segmentation and exhibits an overall average curve deviation of less than 0.35 m within a range of 100 m forward in trajectory prediction. The source code is available at https://wangzhaoze.github.io/RADxGPS/ .<br
Keywords: Radar; Trajectory; Task analysis; Roads; Point cloud compression; Spaceborne radar; Global Positioning System; Intelligent transportation systems; semantic scene understanding; automotive radar; cross-modal learning

Cross-Polarized Imaging of Glass-Fibre Reinforced Plastics at mm-Waves - Nezadal, Martin; Schür, Jan; Schmidt, Lorenz-Peter (8th German Microwave Conference (GeMiC2014), 2014)
The non-destructive testing of compound materials, especially glass-fibre reinforced plastics (GFRP) with millimetrewaves looks very promising. This paper investigates an imaging system which evaluates the cross-polarized signal in the W-Band from 75 to 110 GHz with a synthetic aperture radar. As anomalies reflect the incoming signal in the parallel and orthogonal polarization, it has some advantages for defect detection. It was possible to locate all defects in the measured samples even in depths of up to 14.5mm in GFRP with diameters of down to 5 mm.
lhft_intern.bib::Nezadal2014

Crosstalk Simulation of Multiple Insulated Twisted Pairs based on Transmission Line Theory - Distler, Felix; Gold, Gerald; Thurn, Karsten; Schür, Jan; Vossiek, Martin (21st IEEE Workshop on Signal and Power Integrity (SPI 2017), 2017)

Current limited superconducting RF coils - Stumpf, Christopher; Frank, Tobias; Vester, Markus; Martius, Siegfried; Rehner, Robert; Engelbrecht, Rainer; Schmidt, Lorenz-Peter (Intl. Soc. Mag. Reson. Med. 22th, 2014)
lhft_intern.bib::Stumpf2014

Data Compression for Close-Range Radar Imaging - Rückert, Rainer; Ullmann, Ingrid; Vossiek, Martin; Kaup, André; Herglotz, Christian (IEEE Transactions on Radar Systems, 2024)

Data Statistics and Image Properties of a Large Multistatic mm-Wave Imaging System - Schießl, Andreas; Ahmed, S. S.; Schmidt, Lorenz-Peter (14th International Radar Symposium IRS2013, 2013)
Near field radar systems offer potential solutions for security and non-destructive testing appplications. This work presents the system architecture of a fully electronic multistatic mm-wave imager at E-band. The measurement and processing chain of the imaging system is reviewed along with the corresponding data statistics. Reconstructed data of a complex test pattern with specific 3D elements is used to demonstrate the high imaging performance of the system. © 2013 German Inst of Navigation.
UnivIS-Import:2015-04-16:Pub.2013.tech.IE.LEH.datast

DC- and IF-noise performance optimization of GaAs Schottky diodes for THz applications - Cojocari, O.; Biber, Stephan; Mottet, B.; Rodriguez-Girones, M.; Hartnagel, H.; Schmidt, Lorenz-Peter (Semiconductor Science and Technology, 2005)
This paper presents results which originated from a long-term systematic optimization of surface processing prior to anode formation of THz Schottky-based components. Particularly, four most promising surface-processing approaches are carefully investigated separately and in combination in order to understand the chemical and physical processes occurring on a GaAs surface. A reliable technological approach for anode formation is identified, which exhibits optimal diode characteristics and production repeatability. A model is proposed for the influence of each process on the subsequent one in the fabrication process sequence. DC- and IF-noise measurements are performed using an automated measurement system providing statistically significant data. Very good de-parameters such as a series resistance of Rs = 15 ω, an ideality factor N = 1.168, a reverse current Is = 0.024 fA and an IF-noise temperature of 257 K at 1 mA current bias with a good uniformity are achieved for non-cooled Schottky diodes with an anode diameter of 1 μm. The best noise figure is measured to be as low as 220 K at 3.8 GHz and 1 mA current bias.
UnivIS-Import:2015-03-09:Pub.2005.tech.IE.LEH.dcandi

Deep Learning Based Image Enhancement for Automotive Radar Trained with an Advanced Virtual Sensor - Schüßler, Christian; Hoffmann, Marcel; Ullmann, Ingrid; Ebelt, Randolf; Vossiek, Martin (IEEE Access, 2022)
This paper introduces a novel deep learning based concept for image enhancement and distortion suppression in automotive radar signal processing. The deep neural network (DNN) is trained solely on virtual data that is generated by an automotive MIMO radar ray tracing simulator. The simulator mimics the raw data that would be provided by a specific automotive MIMO radar for which the signal processing is envisaged. This virtual radar sensor, which has the same properties as the real radar, creates the DNN training input data. The unique feature of our approach is that an advanced virtual radar sensor is used to create the target values for the DNN training. The advanced virtual sensor is a simulated radar that works on the same basic principle as the real radar and its resembling virtual sensor, but is significantly upgraded in terms of performance. In our experiments the advanced virtual sensor, e.g., has a notably larger array, i.e., a much better lateral resolution, than the real radar. In addition, our advanced virtual sensor is not affected by multi-path effects, clutter, noise, beamforming sidelobes and other typical automotive radar distortions. The paper shows that a DNN trained on this advanced virtual sensor training data can deliver outstanding automotive radar signal processing results not only on simulated data but also on field data. The presented real-world automotive radar measurements show that multi-path, clutter and noise are efficiently suppressed by this DNN and that it has a remarkable ability to sharpen images and suppress sidelobes. The results presented in the paper suggest that the novel advanced DNN training concept based on virtual sensors offers opportunities that also go far beyond the radar signal processing capabilities illustrated. Hence, the concept put forward here is an attractive option for placing DNN-based radar signal processing on a novel and easy-to-implement foundation.<br
Keywords: Radar Imaging; Automotive Radar; Deep Neural Networks; Image Enhancement; Radar Simulation

Deep Learning-Based Segmentation for the Extraction of Micro-Doppler Signatures - Martinez Garcia, Javier; Vossiek, Martin (Proceedings of the European Microwave Week (EuRAD), 2018)
We present a method for extracting micro-Doppler signatures using a deep convolutional neural network that learns to identify and separate relevant micro-Doppler components from the background. A modified convolutional neural network (fully convolutional network) is trained end-to-end to perform dense predictions from the micro-Doppler signature at the input, generating a map with labels on a pixel level at the output. The network learns intermediate representations with the characteristic patterns of the micro-Doppler paths generated by individual scatterers and is capable of identifying and locating them in the time-frequency representation. The model trained on a simulated environment shows very good performance metrics even in noisy environments, and the experimental results with a continuous wave (CW) radar at 24 GHz indicates that the model can be applied to real scenarios. Moreover, the method scales properly to more complex signatures when several components are superimposed in the time-frequency representation, which indicates that this concept might represent a promising approach for interpreting complex micro-Doppler signature
lhft_intern.bib::Martinez18b

Deep learning for terahertz image denoising in nondestructive historical document analysis - Dutta, Balaka; Root, Konstantin; Ullmann, Ingrid; Wagner, Fabian; Mayr, Martin; Seuret, Mathias; Thies, Mareike; Stromer, Daniel; Christlein, Vincent; Schür, Jan; Maier, Andreas; Huang, Yixing (Scientific Reports, 2022)
Historical documents contain essential information about the past, including places, people, or events. Many of these valuable cultural artifacts cannot be further examined due to aging or external influences, as they are too fragile to be opened or turned over, so their rich contents remain hidden. Terahertz (THz) imaging is a nondestructive 3D imaging technique that can be used to reveal the hidden contents without damaging the documents. As noise or imaging artifacts are predominantly present in reconstructed images processed by standard THz reconstruction algorithms, this work intends to improve THz image quality with deep learning. To overcome the data scarcity problem in training a supervised deep learning model, an unsupervised deep learning network (CycleGAN) is first applied to generate paired noisy THz images from clean images (clean images are generated by a handwriting generator). With such synthetic noisy-to-clean paired images, a supervised deep learning model using Pix2pixGAN is trained, which is effective to enhance real noisy THz images. After Pix2pixGAN denoising, 99% characters written on one-side of the Xuan paper can be clearly recognized, while 61% characters written on one-side of the standard paper are sufficiently recognized. The average perceptual indices of Pix2pixGAN processed images are 16,83, which is very close to the average perceptual index 16.19 of clean handwriting images. Our work has important value for THz-imaging-based nondestructive historical document analysis.<br
Keywords: Deep learning; Terahertz imaging; Historical document analysis; Nondestructive testing

Deep UV Formation of Long-Term Stable Optical Bragg Gratings in Epoxy Waveguides and Their Biomedical Sensing Potentials - Hessler, Steffen; Rüth, Marieke; Lemke, Horst Dieter; Schmauß, Bernhard; Hellmann, Ralf (Sensors, 2021)
In this article, we summarize our investigations on optimized 248 nm deep ultraviolet (UV) fabrication of highly stable epoxy polymer Bragg grating sensors and their application for biomedical purposes. Employing m-line spectroscopy, deep UV photosensitivity of cross-linked EpoCore thin films in terms of responding refractive index change is determined to a maximum of ∆n = + (1.8 ± 0.2) × 10−3 . All-polymer waveguide Bragg gratings are fabricated by direct laser irradiation of lithographic EpoCore strip waveguides on compatible Topas 6017 substrates through standard +1/-1-order phase masks. According near-field simulations of realistic non-ideal phase masks provide insight into UV dose-dependent characteristics of the Bragg grating formation. By means of online monitoring, arising Bragg reflections during grating inscription via beforehand fiber-coupled waveguide samples, an optimum laser parameter set for well-detectable sensor reflection peaks in respect of peak strength, full width at half maximum and grating attenuation are derived. Promising blood analysis applications of optimized epoxy-based Bragg grating sensors are demonstrated in terms of bulk refractive index sensing of whole blood and selective surface refractive index sensing of human serum albumin.
CRIS-Team Scopus Importer:2021-06-11
Keywords: Blood analysis; Bragg grating; EpoCore; Excimer laser; Human serum albumin; Optical sensor; Rapid test; Refractive index sensing

Demonstration of an Efficient High Speed Communication Link Based on Regenerative Sampling - Carlowitz, Christian; Vossiek, Martin (International Microwave Symposium (IMS2017), 2017)

Depth Camera Motion Tracking for Motion Compensation and ISAR Imaging in Walk-Through Security Scanners - Ullmann, Ingrid; Root, Konstantin; Vossiek, Martin (IEEE Journal of Microwaves, 2025)
This paper investigates the fusion of radar and depth camera for maintaining high-quality radar images in walk-through security scanners with significantly reduced array geometries. Therefore, after sensor calibration, the reconstruction volume is initially divided into sub-volumes and linked to the closest body part of a walking person being scanned. The depth camera's motion tracking provides the location and orientation of each body joint during the gait, allowing us to determine their trajectory and velocity. This information is then used to compensate for movement in the image reconstruction of each recorded radar frame. Afterwards, the motion compensated images are then superimposed to one ISAR image, considering the complete trajectory of the person. We conducted measurements with a 3.6GHz-to-10.6GHz walk-through security scanner and a real person carrying various objects. Motion tracking with a depth camera shows promising results for both imaging approaches. In the motion-compensated images, small details became visible and focused compared to reconstruction results without applied motion compensation. The ISAR approach demonstrated effective alignment of individual frames into one superimposed image, producing a full-body image even with a reduced array dimension. While these results prove the benefit of the fusion of radar and depth camera, further investigations into array design are necessary, as object visibility is strongly affected by the selected array geometry for ISAR imaging. This fact could complicate the reliable detection of potential threat objects with a downsized imaging arra
Keywords: Geometry; Tracking; Imaging; Radar; Radar imaging; Cameras; Radar tracking; Motion compensation; Security; Image reconstruction; ISAR; motion compensation; MIMO radar; personnel screening; radar imaging; security scanning

Der ideale Leistungsaddierer - moegliche Realisierung mit Paradox-Richtungsleitungen im Mikrowellenbereich - Brand, Hans (1986)
lhft_intern.bib::thirty_years_LHFT_221

Der Mensch und sein Handy - wie gefährlich ist das elektromagnetische Strahlungsfeld eines Mobilfunkgerätes - Brand, Hans; Dlouhy, R; Schaller, G (1997)
lhft_intern.bib::thirty_years_LHFT_407

Design and Additive Manufacturing of an E-Plane 1-to-9 Power Divider for Satellite Communication - Bachbauer, Felix; Pietschmann, Simon; Shi, Jing; Gold, Gerald (2025 IEEE Radio and Wireless Symposium (RWS), 2025)
A very compact power divider concept in rectangular waveguide technology is presented, whereby the divider can basically be adapted to the required number of outputs. A 1-to-9 divider is shown as an example in this article. This novel divider concept is particularly suitable for applications with special requirements in terms of weight and space, such as miniature satellites, i.e. CubeSats. It is intended to be placed between the power amplifier and the phase shifter. The phase shifters are also designed as waveguides, thus avoiding conventional multi-stage dividers. The use of a quasi sector horn-shaped structure results in a very light weight and compact component. Additive manufacturing of the plastic base body with subsequent metalization and the slotted waveguide technology also ensure considerable weight saving
CRIS-Team Scopus Importer:2025-04-01
Keywords: power dividers; additive manufacturing; space communication; CubeSat

Design and Analysis of 3D Printed Hybrid Couplers for D-Band Applications - Lomakin, Konstantin; Klein, Laura; Gold, Gerald (International Journal of Microwave and Wireless Technologies, 2021)
This work focuses on the impact of the build orientation on additively manufactured waveguide based hybrid couplers for D-band frequency range and relates it to other sources of uncertainty within the overall manufacturing process and measurement instrumentation for the D-band frequency range. The designed specimens are first printed from UV curable photopolymer resin and subsequently metal coated by an electroless silver plating process, which in turn is improved by making use of the slotted waveguide approach. Although the requirements towards geometrical precision to achieve phase errors below 10 ◦ are in an order of 0.1 mm, a desktop grade DLP printer is utilized in this work in order to point out the prospects and limitations of additive manufacturing. Furthermore, waveguide paths with bends are part of the model and their impact on the measured attenuation is estimated explicitly. Despite this narrow field of tolerances, one specimen could have been realized), which achieves a measured output magnitude imbalance of 0.7 dB over the frequency range from 120 to 155 GHz while at the same time exhibiting a phase deviation of only <10 ◦ from the desired 90 ◦ . With these demonstrated results, the proposed approach provides suitability for future applications in the D-band frequency range. <br
Keywords: additive manufacturing; 3D printing; slotted waveguides; electroless plating; manufacturing tolerances; D-Band hybrid coupler

Design and Analysis of 3D Printed Slotted Waveguides for D-Band using Stereolithography and Electroless Silver Plating - Lomakin, Konstantin; Sippel, Mark; Helmreich, Klaus; Gold, Gerald (2020 IEEE/MTT-S International Microwave Symposium (IMS), 2020)
This work demonstrates the feasibility of entirely additively manufactured slotted waveguides in combination with an electroless silver plating process for applications in the D-Band frequency range. Design rules are adjusted towards the requirements for 110-170 GHz and analyzed with respect to the limitations of conventional desktop SLA- and DLP printers. Measurements obtained in this work reach attenuation levels in the order of 20-35 dB/m, hence comparable to conventionally manufactured waveguides. Furthermore, it is shown, that the electrical behavior of slotted waveguides is similar to a conventional waveguide by comparison with simulation model

Design and characterization of a compact and robust shielded dielectric waveguide for mmW applications - Distler, Felix; Oppelt, Daniel; Schür, Jan; Vossiek, Martin (Proceedings of the GeMiC 2018 - The 11th German Microwave Conference (GeMiC 2018), 2018)

Design and construction of an ultrawideband backward wave directional coupler - Hrobak, Michael; Sterns, M.; Seler, Ernst; Schramm, Marcus; Schmidt, Lorenz-Peter (IET Microwaves Antennas & Propagation, 2012)
In this study the design and construction of an ultrawideband backward wave directional coupler is presented. The symmetric, non-uniform coupler covers the frequency range from 2 to 50 GHz with an average coupling of 16.6 2.4 dB while establishing directivity values greater than 10 dB from 10 MHz to 33.8 GHz and 8 dB up to 48.4 GHz. The design is based on coupled microstrip lines suitable for integration into planar front end modules of modern measurement systems. To account for the dispersive behaviour of such waveguides, wiggly-line technique is utilised. Accurate extraction of the waveguide frequency-dependent distributed equivalent circuit parameters is done by 2D finite element electromagnetic field (EM) simulation. To balance out the remaining mistuning appropriate scaling parameters are introduced. The influence of common manufacturing and assembly tolerances on the device performance is analysed. Measurement results of the synthesised coupler with planar matched isolated port are presente
lhft_intern.bib::hrobakIetCoup

Design and Experimental Verification of Correction Algorithms for Improving the Measurement Accuracy of a Broadband Vector IF Receiver at 160 MHz - Hofmann, A.; Kalb, A.; Manglberger, M.; Weinzierl, Jochen; Schmidt, Lorenz-Peter (Frequenz, Mai / Juni, 2005)
An Intermediate Frequency (IF) receiver unit with a center frequency of 160 MHz and a bandwidth of 80 MHz was recently developed as a core component of a novel heterodyne vector field measurement system at 150 GHz, 300 GHz and 450 GHz. The influence of different errors types on the measurement accuracy is systematically analyzed. Based on this, a strategy of enhancing the overall accuracy of the IF receiver by software algorithms was developed. Its effectiveness is verified by experimental characterization.
UnivIS-Import:2015-04-16:Pub.2005.tech.IE.LEH.design_4
Keywords: Accuracy enhancement; Correction algorithms; Iq demodulation; Thz measurements; Vector receiver

Design and Fabrication of Broadband Hybrid GaAs Schottky Diode Frequency Multipliers - Hrobak, Michael; Sterns, Michael; Schramm, Marcus; Stein, Wadim; Schmidt, Lorenz-Peter (IEEE Transactions on Microwave Theory and Techniques, 2013)
Frequency extender modules of vector network analyzers and signal generators, as well as front-end modules of semiconductor automatic test systems, make use of broadband resistive diode frequency multipliers. This paper presents the design and fabrication of innovative planar varistor frequency multipliers. Three frequency triplers (#1, #2, #3) and two frequency doublers (#4, #5), operating in the 60-110 GHz and 50-110 GHz frequency ranges, respectively, are designed. The hybrid architecture utilizes commercial gallium arsenide Schottky diodes from United Monolithic Semiconductors on thin-film processed high-permittivity alumina substrate. Synthesis is based on a co-simulation procedure between 3-D electromagnetic field and nonlinear harmonic balance circuit simulations. Scalar and spectral measurement data over the focused output frequency ranges are presented. Conversion loss values around 18 dB from 60 to 95 GHz and below 22 dB from 60 to 110 GHz are achieved with frequency tripler #1. Frequency doubler #5 achieves conversion loss values below 15 dB from 50 to 89 GHz and below 22 dB from 50 to 110 GHz. A comprehensive comparison of the presented work with reported frequency multipliers is included. © 2013 IEE
UnivIS-Import:2015-03-09:Pub.2013.tech.IE.LEH.design
Keywords: 1.00-mm coaxial connector; Hybrid multiplier; Longitudinal E-field probe; Planar W -band multiplier; Schottky diode frequency multiplier; Varistor doubler; Varistor tripler

Design and Measurement Characterization of Two 300 GHz Fan-In Antennas in Package for Upcoming Sub-THz Applications - Pfahler, Tim; Vossiek, Martin (2024 54th European Microwave Conference, EuMC 2024, 2024)
This paper presents the design and measurement characterization of two antennas in package (AiP) feeding concepts in the chip's fan-in wafer level ball grid array (WLB) at 300 GHz. The key advantage of the two designs is the vertical integration of the AiPs, directly above the integrated circuit (IC), instead of lateral antenna placement as in fan-out WLB. This minimizes the separation of package and IC components, resulting in minimal insertion loss (IL) at the IC to package transition. A probe-feed AiP, using a through-mold-via (TMV), and an electro-magnetic (EM) coupled AiP are presented and described in detail. Both AiPs are verified by measuring the return loss, the frequency-dependent antenna gain, and the radiation pattern. The measured -10 dB matching bandwidth of the probe-feed AiP and EM-coupled AiP is 36 GHz and 12 GHz, respectively. Furthermore, a laser scanning microscope was used to determine manufacturing tolerances and to account for deviations in the frequency response between measurement and simulation. A simulated antenna peak gain beyond 5.5 dBi emphasizes the underlying packaging approach to compensate for the free-space loss at 300 GHz for future sensing and communication systems in package applications.
CRIS-Team Scopus Importer:2024-12-13
Keywords: Antennas-in-package (AiP); fan-in WLB (wafer level ball grid array); system-in-package (SiP); wafer level packaging

Design and Measurement of a Bandpass Filter at 300 GHz Based on a Highly Efficient Binary Grating - Biber, Stephan; Hofmann, Arnd; Schulz, R; Collischon, M; Weinzierl, Jochen; Schmidt, Lorenz-Peter (IEEE Transactions on Microwave Theory and Techniques, 2004)
A bandpass filter for 300 GHz with a stopband at 450 GHz based on a highly efficient binary grating as a frequency-selective element was developed and optimized. The geometry of the grating was carefully designed for a maximum difference angle between reflected beams at 300 and 450 GHz and for maximum efficiency at 300 GHz. The grating efficiency was optimized using a rigorous theory of diffraction, yielding a maximum efficiency of over 99.5% neglecting conductor losses. Antennas and elliptical mirrors are used for optimum quasi-optical illumination of the grating and Gaussian beam shaping. After an optimization and a comprehensive examination of the grating in an experimental heterodyne measurement setup at 300 GHz, the filter was implemented fixed tuned into a small housing with waveguide flanges. The fixed tuned setup with corrugated feed horns results in an overall flange-to-flange insertion loss of only 2.8 d
lhft_intern.bib::biber04b

Design and Measurement of a Wideband Aperture-Coupled and Polarization-Agile Stacked-Patch Antenna-Array for Monopulse Radar Applications - Methfessel, Sebastian Dirk; Schmidt, Lorenz-Peter (European Conference on Antennas and Propagation EuCAP, Berlin, March, 2009)
A wideband, circularly-polarized antenna array covering the frequency range 1.7 GHz to 2.5 GHz for telemetric monitoring and monopulse application is presented. Using a subarray design, monopulse functionality can be achieved with an external comparator network. The high bandwidth of 38 % is realized by using the principle of the aperture-coupled stacked-patch microstrip antenna. By integrating a quadrature coupler, the polarization sense can be selected. Sequential rotation technique is used for enhancing polarization purity. The theoretical analysis is based on the finite-difference time-domain (FDTD) method. A stacked-patch antenna element, a 2×2 antenna quadrant and a 4x4 antenna array have been designed, fabricated and measured. The measured return loss of one quadrant is better than 11 dB in the desired bandwidth for both circular polarization senses. Maximum antenna gain ranges between 7 dB and 18 dB for the sum pattern while the null depth of the difference pattern is always better than 30 dB. Theoretical and measured results of S parameters and radiation patterns are presented and discussed.
UnivIS-Import:2015-04-16:Pub.2009.tech.IE.LEH.design_7

Design and Measurements of Frequency Selective Surfaces on Silicon Substrates for Sub-mm Wave Applications - Biber, Stephan; Bozzi, M.; Perregrini, L.; Schmidt, Lorenz-Peter (ACES Conference of the Applied Computational Electromagnetic Society, 2005)
UnivIS-Import:2015-04-16:Pub.2005.tech.IE.LEH.design_7

Design and Optimization of Amplitude-Modulated Microwave Backscatter Transponders - Aleksieieva, Anna; Vossiek, Martin (5th German Microwave Conference (GeMiC2010), 2010)
In the current paper design rules and exemplary optimized designs for microwave backscatter transponders are presented. The overall goal of the proposed transponder design is to achieve a maximum signal to noise ratio in the radar signal of a given base-station that interrogates the transponder. To accomplish this task, it is important not only to consider the transponder modulation factor, i.e. the values of modulated / switched antenna loads, but also the resulting radar cross-section of the loaded transponder antenna. Unfortunately, both aspects are partly opposing and optimization is not straightforward. The design method presented and applied in this paper allows selecting the optimal relation between the antenna parameters and the load parameters. To prove the proposed method, exemplary designs and measurement results of 5.8 GHz backscatter transponders are shown.
lhft_intern.bib::Aleksieieva2010

Design and Optimization of Sparse Planar Antenna Arrays for Wireless 3-D Local Positioning Systems - Pavlenko, Tatiana; Reustle, Christoph; Dobrev, Yassen; Gottinger, Michael; Jassoume, Laila; Vossiek, Martin (IEEE Transactions on Antennas and Propagation, 2017)
In this paper the design and measurement verification of optimized planar sparse arrays for use in wireless localization applications are presented. Existing literature on array optimization has mainly been concerned with arrays intended for imaging applications. As the array requirements for 3-D localization in multipath environments are essentially different, we made an analysis of the array parameters important for this specific application. The set of challenging practically relevant requirements for the optimization of the planar array layout was defined, including a restriction to a small number of antennas and minimal interelement distance bigger than λ/2 . An adapted multi-objective particle swarm optimization stochastic algorithm was employed to optimize array for the robust and precise direction of arrival of a single source inside a wide angular scan range up to ±60° in azimuth and elevation planes. Two optimized receive arrays consisting of eight patches were manufactured and measured to present the trade-off achieved under the desired requirements. The effects of optimized array parameters on the performance of 3-D positioning are validated by angle measurements in an anechoic chamber and different indoor scenario

Design and Testing of Frequency-Selective Surfaces on Silicon Substrates for Submillimeter-Wave Applications - Biber, Stephan; Bozzi, M.; Günther, O.; Perregrini, L.; Schmidt, Lorenz-Peter (IEEE Transactions on Antennas and Propagation, 2006)
A new class of frequency-selective surfaces (FSSs), to be used as quasi-optical filters for harmonic suppression in submillimeter-wave frequency multipliers, is proposed and experimentally verified. The FSSs consist of two-dimensional aperture arrays and are made from microstructured aluminum on electrically thick, high-resistivity silicon substrates. This leads to a very good mechanical stability, reasonably low insertion loss, and permits manufacture of the structure by using standard processes available from the semiconductor industries. This paper presents the design, fabrication, and testing of two sets of prototypes, the former with a passband at 300 GHz and a stopband at 450 GHz and the latter with a passband at 600 GHz and a stopband at 750 GHz. For both frequency ranges, FSSs with rectangular slots and with dogbone-shaped holes have been designed by using the method of moments/boundary integral-resonant mode expansion method. The effect of ohmic and dielectric losses has been determined by using the commercial code HFSS. Several prototypes have been fabricated, and measured by terahertz time-domain spectroscopy and continuous wave measurements, showing high reproducibility of the machining process, insertion loss between 1.0 and 1.6 dB, and stopband attenuation larger than 30 dB. Finally, we demonstrate that the incidence angle can be used as a degree of freedom for fine tuning the stopband, without practically changing the frequency response in the passband. © 2006 IEEE.
UnivIS-Import:2015-03-09:Pub.2006.tech.IE.LEH.design
Keywords: Frequency multipliers; Frequency-selective surfaces; Quasi-optics; Silicon; Submillimeter-wave technology

Design and Testing of Frequency Selective Surfaces on Thick Silicon Substrate Operating at 600 GHz - Biber, Stephan; Bozzi, M.; Günther, O.; Perregrini, L.; Schmidt, Lorenz-Peter (European Microwave Week, Paris, France, September, 2005)
This paper describes the design and experimental verification of frequency selective surfaces, to be used as quasi-optical niters in the sub-millimeter wave range. They consist of a thin metal layer perforated periodically with rectangular or dogbone-shaped holes, and supported by a thick silicon substrate. A set of filters with pass-band at 600 GHz and stop-band at 750 GHz have been designed and tested. The design procedure based on the MoM/BI-RME method, the manufacturing of prototypes by standard processes available from the semiconductor industries, and their measurement by CW and THz time-domain spectroscopy are reported in this work. This class of filters is mechanically robust, presents low losses (1.4 dB), exhibits good reproducibility, and permits a fine tuning of the stop-band frequency by slightly changing the incidence angle.
UnivIS-Import:2015-04-16:Pub.2005.tech.IE.LEH.design

Design, Calibration and Validation of 24 GHz Resonators for Epoxy Resin Cure Monitoring Systems in the Fibre-Reinforced Plastics Fabrication - Groh, Jannis; Schür, Jan; Javdanithehran, Mehdi; Ziegmann, Gerhard; Vossiek, Martin (Proc. 19th World Conference on Non-Destructive Testing, 2016)
lhft_intern.bib::Groh2016a

Design considerations for a fixed tuned 300 GHz Heterostructure Barrier Charge Swing tripler - Ruf, Marcel; Schür, Jan; Bogdan, N.; Schmidt, Lorenz-Peter; Hartnagel, H. (Proceedings of the 3rd German Microwave Conference, 2008)
A simulative investigation of a microstrip-based environment for a planar Heterostructure Barrier Charge Swing multiplier optimized for tripler operation from 100 GHz to 300 GHz is presented. Design considerations for both the planar circuitry and the geometrical dimensions of the split-block mount are given. Results obtained by full 3D electromagnetic software simulations are presented and experimentally validated by transmission measurements of scaled models of antipodal finline tapers in W-band frequency range.
UnivIS-Import:2015-04-16:Pub.2008.tech.IE.LEH.design

Design considerations for the hot embossing of microstrip antennas on plastic foils - Kilian, Andreas; Fuchs, Manuel; Schmidt, Lorenz-Peter (International Journal of Microwave and Wireless Technologies, 2009)
In this contribution, fundamental design considerations for a novel metallization technique to realize millimeter-wave microstrip structures are presented. This hot embossing technology is a fast and economic process originating from the production of three-dimensional molded interconnect devices. Conductive structures are coated onto plastic parts or plastic foils using a heated stamp. This approach shows high potential and therefore will be investigated for the fabrication of low-cost printed antennas at millimeter-wave frequencies. The focus of this contribution is on design guidelines considering process parameters and interactions with substrate and copper foil characteristics derived from the fabrication and measurement of single microstrip patch antenna prototypes for radar applications in the industrial, scientific and medical (ISM) band at 24GHz. Far-reaching potential lies in the utilization of the three-dimensional manufacturing technology for the construction of conformal integrated antenna systems based on the thermoforming capabilities of polymer substrates. © 2009 Cambridge University Press and the European Microwave Association.
UnivIS-Import:2015-03-09:Pub.2009.tech.IE.LEH.design
Keywords: Hot embossing; Low-cost fabrication; Metallization technique; Microstrip patch antenna; Molded interconnect devices

Design, Fabrication, and application of precise delay lines at 2.45 GHz - Ruppel, C. C. W.; Reindl, Leonhard; Berek, S.; Knauer, Uwe; Heide, Patric; Vossiek, Martin (IEEE International Ultrasonics Symposium, 1996)
For years linear optimization algorithms have been used successfully in bandpass filter design. This method has been adopted for the design of dispersive interdigital transducers (IDTs) for pulse compression filters with low time-bandwidth products, and for the design of delay lines with linear phase. Now this method has been extended to the design of dispersive IDTs operating at higher harmonics. As examples, delay lines at 2.45 GHz operating at the fundamental and third harmonic with relative bandwidths up to 30% will be presented. The delay lines operating at the fundamental harmonics were fabricated on the rotated cut of LiNbO3 and had normal fingers only. The relative height of the metallization was chosen for minimum reflections. Minimum linewidth of 0.3 μm were necessary. The delay lines operating at the third harmonic had split fingers for canceling reflections. Therefore minimum linewidths of approximately 0.45 μm had to be realized. Measured and calculated frequency responses of these delay lines will be compared with each other. Taking advantage of the reported delay lines, a novel FMCW radar system incorporating a 2.45 GHz SAW reference path is established. The proposed SAW based system achieves a higher dynamic range than the conventional FMCW radar sensors.
UnivIS-Import:2015-04-16:Pub.1996.tech.IE.LEH.design

Design, fabrication, and application of precise SAW delay lines used in an FMCW radar system - Reindl, Leonhard; Ruppel, C. C. W.; Berek, S.; Knauer, Uwe; Vossiek, Martin; Heide, Patric; Oreans, L. (IEEE Transactions on Microwave Theory and Techniques, 2001)
An inexpensive frequency-modulated continuous-wave (FMCW) radar system is presented in this paper, which, nevertheless, meets all industrial requirements. The FMCW radar uses a low-cost nonlinear voltage-controlled oscillator (VCO), operating at an IF of 2.45 GHz to generate the frequency modulation of the radar system. This VCO signal is applied twice, first to generate the radar transmitter signal at 24 GHz, and then it is fed to a surface acoustic wave (SAW) delay line. The SAW delay line generates a fixed delay time, which corresponds with a fixed radar distance. Thus, all systematic nonlinearities and stochastic phase errors of the FMCW system can be monitored and, afterwards, can be compensated for in real time. This linearization technique leads to a significant enhancement in dynamic range for a FMCW radar system. For this FMCW system, SAW delay lines with a linear phase characteristic have been designed using a linear optimization program. The delay line consists of two chirped and weighted interdigital transducers. For high volume, low-cost, and high-yield production of the required SAW structures, with linewidths down to 0.3 μm, technological improvements had to be achieved, especially in photolithography. Based on these design and fabrication techniques, delay lines at 2.45 GHz operating at the fundamental and third harmonic with bandwidths up to 800 MHz have been realized.
UnivIS-Import:2015-03-09:Pub.2001.tech.IE.LEH.design
Keywords: 0.3-μm linewidth; Chirp; FMCW radar; Linearization; Photolithography; SAW delay line; Tank level gauge; Weighted IDTs

Design of a 4th Harmonic Schottky Diode Mixer for THz Frequencies - Schür, Jan; Ruf, Marcel; Schmidt, Lorenz-Peter (32th International Conference on Infrared and Millimeter Waves, 2007)
This paper focuses on the benefits of subharmonic mixers in the sub-mm wavelength range. To demonstrate the possibility to extend the advantages of 2nd harmonic mixers with respect to local oscillator requirements the paper discusses higher order subharmonic mixers. Simulation results are presented to show the achievable performance and limitations of higher order subharmonical mixing. For an exemplary 4th harmonic mixer operating at 600 GHz the circuit simulations predict a conversion loss of around 15 dB. Results of 3D-EM field simulations are presented to demonstrate a very compact split-block realization of the mixer circuitry.
UnivIS-Import:2015-04-16:Pub.2007.tech.IE.LEH.design
Keywords: 4th harmonic; 600 GHz; GaAs Schottky diode; Mixer; THz

Design of a Balanced-Fed Patch-Excited Horn Antenna at Millimeter-Wave Frequencies - Methfessel, S.; Schmidt, Lorenz-Peter (European Conference on Antennas and Propagation, EuCAP 2010, Barcelona, Spain, April, 2010)
In this paper, a patch-excited horn antenna with a center frequency of 79 GHz is introduced. Its plane of polarization can be rotated by 45° relative to the balanced feed, which is useful for multi-element array radar applications with digital beam forming (DBF) capabilities, where easy planar integration with transceiver chips is essential. The stacked conical horn is responsible for the high gain radiation pattern while maintaining the planar nature of the patch element. The non rotated but matched antenna has a measured gain of more than 8 dBi in boresight direction, while the sideway radiation is always 20 dB lower than the main beam, reducing mutual coupling and crosstalk. Radiation characteristics are enhanced with a substrate integrated cavity. This design achieves a relative bandwidth of 18 % by using an aperture coupled patch element. Simulation and measurement are in good agreement. After an introduction, the design of three antenna variants is presented, including some simulation results. The paper will be concluded by the measurement setup and measurements of the radiation pattern and return loss.
lhft_intern.bib::Methfessel10

Design of a Controllable Attenuator with High Dynamic Range for THz-Frequencies based on Optically Stimulated Free Carriers in High-Resistivity Silicon - Biber, Stephan; Schneiderbanger, Dirk; Schmidt, Lorenz-Peter (Frequenz, June, 2005)
As the variety of passive circuit components for the 0.3-5 THz domain is rarely developed, we examine the possibilities to use electro-optically stimulated high resistivity float-zone silicon for the design of a tunable attenuator for quasi-optical systems operating at 580 GHz. Possible applications also include switches and modulators for millimeter and submillimeter-waves. A fiber-coupled 1W CW near infrared (MIR) diode-laser is used to illuminate a silicon slab and creates electron-hole pairs in the bulk silicon. At the operating frequency, the silicon slab acts as a Fabry-Perot resonator to minimize insertion loss due to unwanted reflections from the air-silicon interface. A second silicon slab with micromachined anti-reflection coating is used to shield the NIR to ensure safe operation. We achieve more than 35 dB dynamic range with an insertion loss of less than 0.5 dB.
UnivIS-Import:2015-04-16:Pub.2005.tech.IE.LEH.design_3
Keywords: Electro-optical effects in silicon; Quasioptics; THz-technology; Variable attenuator

Design of an Optimized Linear Sparse Antenna Array for a 24 GHz Radar Tachymeter - Pavlenko, Tatiana; Reustle, Christoph; Thurn, Karsten; Shmakov, Denys; Ebelt, Randolf; Vossiek, Martin (2015)
This paper presents the design of a linear antenna array for use in a 24 GHz radar tachymeter. The task of the proposed radar tachymeter is the precise measurement of the distance and angle to a cooperative transponder. To obtain the desired high accuracy, we designed an optimized sparse antenna array. The antenna pattern was selected using a brute-force optimization method. A fixed number of array elements was placed on a limited number of allowed grid positions and the array pattern with the best figure of merit for the given radar tachymeter application was selected. This approach can be successfully employed for sparse antenna array designs where multiple constraints such as aperture size limitations or number and spacing of antenna array elements are given. Distance and angle measurements taken with the implemented optimized array show excellent results. The standard deviations in range and azimuth were 8.6 mm and 0.1°, respectively for a range of several hundred meters.

Design of Artificial Dielectrics for Anti-Reflection-Coatings - Biber, Stephan; Martius, Siegfried; Schmidt, Lorenz-Peter; et al. (Proceedings of the 33rd European Microwave Conference, 2003)
With the increasing interest in new artificial materials ranging from meta-materials to photonic bandgap materials there is a growing need for accurate models of artificial materials. We examine the design of a three-layer structure with an artificial dielectric as an anti-reflection-coating on both sides of a dielectric slab. We present a field-equivalent circuit theory to calculate the effective dielectric constant of the structured dielectric. The materials discussed in this paper have a lateral periodicity smaller than λ/10 and can easily be manufactured from high density polyethylene (HDPE) for frequencies up to 20 GHz. The field-analog circuit theory can also be used to calculate the polarization dependence of the artificial dielectric. Theoretical results of three geometrically different structures were compared with waveguide measurements at X-band and showed excellent agreement. Applications such as the design of new components at millimeter and submillimeter wave frequencies are discussed, considering the X-Band measurements as a scaled model. © 2003 EUMA.
UnivIS-Import:2015-04-16:Pub.2003.tech.IE.LEH.design

Design of New Passive THz Devices based on Micromachining Techniques - Biber, Stephan; Schür, Jan; Hofmann, Arnd; Schmidt, Lorenz-Peter (Proc. of Kharkov Symposium on Physics and Engineering of Microwaves, Millimeter and Submillimeter Waves, Kharkov, Ukraine, June, 2004)
We present an overview on the latest results using micromachining techniques far the fabrication of THz-components. Different machining techniques will be discussed with respect to their capability to generate complex 3-dimensional geometries with high aspect ratios and to meet the high mechanical requirements for THz-components. Exemplary results for the application of micromachining techniques for the design of new components will be reviewed. We will emphasize the potential of silicon based microstructures for the manufacturing of new devices.
UnivIS-Import:2015-04-16:Pub.2004.tech.IE.LEH.design_4

Design of Sparse Dome Antenna Array for Angle of Arrival Localization Systems - Pavlenko, Tatiana; Schütz, Martin; Dobrev, Yassen; Vossiek, Martin (13th European Conference on Antennas and Propagation, EuCAP 2019, 2019)
A design of a conformal 16-element patch array with antennas non-uniformly distributed over a hemispherical surface is presented. The considered array type allows 3D-positioning by angle of arrival (AOA) in hemispherical angular coverage that is desired for localization of UAV and other mobile robots in GNSS-denied environments. At the same time, the optimization of antenna positions helps to highly reduce the number of antennas needed to achieve suitable localization accuracy in desired angular range. The realized array was integrated as a receive array of a 24 GHz ISM band local positioning radar unit. Calibration and measurement results with transponder mounted on a 6D positioning system show the applicability of such type of highly sparse conformal array for use in 3D local positioning systems. Thus, the presented array introduces a cost-effective design solution for wireless localization within hemispherical coverage utilizing only two positioning units.
CRIS-Team Scopus Importer:2019-07-16
Keywords: conformal arrays; local positioning system; particle swarm optimization; sparse antenna arrays

Design of Sparse MIMO Arrays for Short Range Imaging Applications - Gumbmann, F.; Schmidt, Lorenz-Peter (Asia-Pacific Microwave Conference (APMC) 2010, 2010)
This paper presents the development of a sparse periodic array for short range imaging applications in the frequency range 75–90 GHz. The basis for the array design is the effective aperture approach, which is a farfield design procedure. For short target distances and a wide field of view the result of this concept is not satisfying. An extension of the sparse periodic array concept for short range applications on the basis of an optimized array design and an optimized beamforming algorithm is presented in this wor
lhft_intern.bib::Gumbmann10

Design Optimization of Pyramidal Horn Antennas for 3D Printing in the mm-Wave Range - Lomakin, Konstantin; Schür, Jan; Gold, Gerald (16th European Conference on Antennas and Propagation (EuCAP), 2022)

Detailed Analysis and Modeling of Phase Noise and Systematic Phase Distortions in FMCW Radar Systems - Tschapek, Peter; Körner, Georg; Carlowitz, Christian; Vossiek, Martin (IEEE Journal of Microwaves, 2022)
In coherent continuous-wave (CW) radar systems, such as frequency-modulated CW (FMCW) radar systems, measurement precision is distorted by phase noise and systematic phase errors during radar signal generation. Unfortunately, to date, these phase distortions have typically been modeled based on many simplifications, often leading to overoptimistic predictions of radar performance. For example, phase noise is regularly considered based on additive white Gaussian noise (AWGN) models, ignoring its colored spectral property. Systematic errors are also frequently not properly separated from stochastic distortions, or not precisely measured and modeled. To overcome these issues, an advanced CW radar and frequency synthesizer model is proposed, analyzed, and experimentally verified in this paper. It is shown how systematic phase errors can be measured and how the influence of phase distortions on radar measurement can be accurately predicted. The proposed modeling approach was investigated for range correlation and range precision. The key metrics are the phase noise power spectral density (PSD) for range correlation and the variance of the frequency estimate for range precision. A 24-GHz FMCW radar system was used for the experimental verification. Long-range radar targets with distances of 38 to 880 m were created with an analog fiber optical link. Therefore, a precise and systematic evaluation of all effects was possible. The proposed phase distortion modeling approach realistically represented the range-dependent radar measurement effects. This enables the most precise simulation of and prediction for FMCW radar performance to dat
Keywords: Noise analysis; noise modeling; range correlation; range precision; FMCW radar

Detection of CO_2 dissociation inside RF excited CO_2 laser plasmas with NIR DFB diode lasers and balanced receivers - Engelbrecht, Rainer; Fenske, T; Brand, Hans (1999)
lhft_intern.bib::thirty_years_LHFT_431

Detection of CO_2 dissociation inside RF excited CO_2 laser plasmas with NIR DFB diode lasers and balanced receivers - Engelbrecht, Rainer; Fenske, T.; Brand, Hans (ICOLS99 (14th Int. Conf. On Laser Spectroscopy, Innsbruck 1999), 1999)
UnivIS-Import:2015-04-16:Pub.1999.tech.IE.LEH.detect

Detection of Moving Targets using Coherent Optical Frequency Domain Reflectometry - Renner, Esther; Köppel, Max; Schmauß, Bernhard (paper W4.82, 2021)
We present Doppler-corrected position and velocity measurement with a fiber-coupled COFDR system based on the FMCW radar principle for high precision localization applications. A high measurement accuracy and the ability to track targets are demonstrated.<br

Detection of SSR Signals in Multipath Airport Environments by a Multichannel Receiver - Reck, C.; Berold, U.; Schmidt, Lorenz-Peter (Asia Pacific Microwave Conference, Yokohama, Japan, December, 2010)
Multipath propagation is a serious problem with Secondary Surveillance Radar (SSR) systems at airport apron and taxiway areas. In this approach, effective suppression of interference (garbling) by multipath components, using a multichannel receiver is presented. Thereby the SSR header format is exploited to detect multipath components, which are then eliminated by subspace based signal suppression. Extensive tests at Frankfurt international airport show the potential of the proposed approach to significantly improve reception at problematic sites.
lhft_intern.bib::Reck10b

Detection of Weak Moving Targets Based on 2-D Range-Doppler FMCW Radar Fourier Processing - Ali, Faiza; Vossiek, Martin (5th German Microwave Conference (GeMiC2010), 2010)
This paper deals with a FMCW radar measurement scheme and a 2-D range-Doppler FMCW radar Fourier processing that is especially suited to detect very weak moving targets. A 2-D Fourier transform is applied to a larger set of consecutively measured FMCW radar beat signals. By this a phase coherent evaluation of a very long measuring time and a highly sensitive target separation in range and Doppler dimension is feasible. Applications of the proposed method are for example live sign detection of trapped or buried people, intruder detection or level measurements to organic fluids. The practical application of the described method is illustrated with a 24 GHz FMCW radar sensor system. The signal evaluation was implemented on a field programmable gate array (FPGA) to facilitate real time processing. Exemplary measurement results are presented to illustrate the capability of the applied method.
lhft_intern.bib::Ali2010

Die Kunststoffkarroserie als Träger mehrlagiger, konformer Folienantennen fuer Automobilradarsysteme - Kilian, Andreas; Schmidt, Lorenz-Peter (WSAA, 2010)
lhft_intern.bib::Kilian10b

Dielectric Data of Ceramic Substrates at High Frequencies - Stiegelschmitt, Alfons; Roosen, Andreas; Ziegler, Christof; Martius, Siegfried; Schmidt, Lorenz-Peter (Journal of the European Ceramic Society, 2004)
UnivIS-Import:2015-03-09:Pub.2004.tech.IE.LEH.dielec

Dielectric Rod Antennas as Optimized Feed Elements for Focal Plane Arrays, Washington - Richter, Jürgen; Schmidt, Lorenz-Peter (Proceedings of the IEEE International Antennas and Propagation Symposium 2005, Washington, D.C.,July, 2005)
Dielectric rod antennas of rectangular cross section have a number of significant advantages over conventional waveguide or horn antennas when used as feed elements in focal plane arrays. They provide a broadband input matching, a much lower mutual coupling and an appreciable reduction of spillover losses even in densely packed feed arrays. The design, simulation, optimization and experimental investigation of feed arrays with waveguide- and slotline-fed dielectric rod antennas at millimeter-wave frequencies is presented.
UnivIS-Import:2015-04-16:Pub.2005.tech.IE.LEH.dielec

Dielectric Rod Waveguide Couplers as Harmonic Filters for Millimeter and Sub-Millimeter Wave Frequencies - Hofmann, A.; Manglberger, M.; Biber, Stephan; Weinzierl, Jochen; Schmidt, Lorenz-Peter; Brand, Hans (GeMiC 2006, Karlsruhe, April, 2006)
UnivIS-Import:2015-04-16:Pub.2006.tech.IE.LEH.dielec

Dielectric waveguides at submillimeter wavelengths - Weinzierl, Jochen; Fluhrer, C; Brand, Hans (IEEE Sixth International Conference on Terahertz Electronics, 1998)
A flexible waveguide system has been simulated using the field calculation program MAFIA, for the first time realised for frequencies up to 150 GHz and operated in two applications. The flexible waveguide system consists of a rectangular, dielectric fibre made of polyethylene combined with optimised tapers and waveguide adapters, which makes the flexible waveguide easy to use in combination with conventional waveguides. A minimum attenuation of 4 dB/m at 140 GHz; has been obtained with the dielectric waveguides, which is about 6 dB less than the measured attenuation of D-band waveguides operated at the same frequency. Additionally the phase shift of the flexible waveguides for different bending radii as well as the influence of different tapered fibre terminations was measured and is reporte
lhft_intern.bib::weinzierl98

Dielectric Wide Angle Lenses for Millimeter-Wave Focal Plane Imaging - Richter, Jürgen; Hofmann, Arnd; Schmidt, Lorenz-Peter (Proceedings of the 31st European Microwave Conference, 2001)
Various design procedures for millimeter-wave dielectric lenses have been studied and compared with regard to the wide angle characteristics of the resulting lens contours. The paper describes the simulation and optimisation of the focusing properties of the lenses for large scanning angles using a hybrid method involving ray-tracing techniques and aperture field integration, the realisation of unzoned and zoned lenses and the farfield pattern measurements at 75 and 150 GHz. The theoretical and experimental results show that a scanning range of 40° (±20°) with very low beam degradation can be achieved. © 2001 IEEE.
UnivIS-Import:2015-04-16:Pub.2001.tech.IE.LEH.dielec

Differential Excitation of a Hybrid Antenna for a 75 GHz Antenna Array Implemented on a Multilayer PC Board - Juenemann, R.; Zielska, A.; Schießl, Andreas; Methfessel, Sebastian Dirk; Schmidt, Lorenz-Peter (43th European Microwave Week, 2013)
If, for practical reasons, there is a need to bend a differential waveguide, the bend has to be compensated to avoid mode conversion into the common mode which can lead to unwanted resonance effects. This paper deals with two possible compensating structures for a 45° bend in a differential waveguide exciting a hybrid antenna. The hybrid antenna in turn is part of a large array used in a security scanner for people screening. Simulations show antenna behavior with and without compensation with respect to matching, mode conversion, gain, and suppression of the cross polarization. © 2013 European Microwave Association.
UnivIS-Import:2015-04-16:Pub.2013.tech.IE.LEH.differ
Keywords: antenna feed; differential amplifier; horn antenna; microwave imaging; mode conversion

Diffraction grating with rectangular grooves exceeding 80% diffraction efficiency - Haidner, H.; März, Martin; Kipfer, Peter; Sheridan, J. T.; Schwider, J.; Streibl, N.; Collischon, Martin; Hutfless, Joachim (Infrared Physics, 1993)
A novel design for a surface relief grating with rectangular grooves is presented. The first reflected diffraction order shows experimentally 84% diffraction efficiency for a metallic grating. The required binary surface relief can be manufactured by using one single microlithographic fabrication step similar to standard processes in microelectronics. Each period of the grating consists of a subwavelength "minilattice" with a variable duty cycle. A theoretical model of the structure is presented and compared to measurements at 10.6 μm wavelength. Applications ranging from deflectors, polarizing beam splitters, variable attenuators to general diffractive components such as kinoforms for laser beam shaping are proposed. © 1993.
Created from Fastlane, Scopus look-up

Diffuser-Based LIDAR Signal Acquisition for Fast and Compact All-Optical Target Simulators - Rittler, Andreas; Carlowitz, Christian (2024 IEEE Photonics Conference (IPC), 2024)
We present a novel approach for all-optical LIDAR signal acquisition over a large field of view, which enables fast and compact LIDAR target simulators. Our diffuser and fast-steering mirror-based setup supports a field of view of at least ±35° with roughly 2° resolutio

Digital Beamforming for Spaceborne Reflector-Based Synthetic Aperture Radar, Part 1: Basic imaging modes - Younis, Marwan; De Almeida, Felipe Queiroz; Villano, Michelangelo; Huber, Sigurd; Krieger, Gerhard; Moreira, Alberto (IEEE Geoscience and Remote Sensing Magazine, 2021)
Deployable reflector antennas illuminated by a digital feed array enable spaceborne synthetic aperture radar (SAR) systems to image an ultrawide, continuous swath at a fine azimuth resolution. This is facilitated by the use of dedicated imaging modes and by multidimensional digital beamforming (DBF) techniques. This article is part 1 of a tutorial trilogy, where a focus is put on the required onboard functionality, operational techniques, and DBF aspects, for which a rigorous mathematical description is included. To maintain general validity, the functional implementation for the various modes is detailed, thus avoiding restricting the description to a specific realization. The reader is assumed to be familiar with the general concept of SAR and, otherwise, referred to the literature on the topic. The approach followed in the trilogy is to start with a basic imaging concept and then move to more advanced modes, thus successively increasing the complexity; the mathematical description follows the same approach.
CRIS-Team WoS Importer:2021-10-08

Digitalized Optical Sensor Network for Intelligent Facility Monitoring - Renner, Esther; Härteis, Lisa-Sophie; Kaiser, Joachim; Villnow, Michael; Richter, Markus; Thiel, Torsten; Pohlkötter, Andreas; Schmauß, Bernhard (Photonics, 2024)
Due to their inherent advantages, optical fiber sensors (OFSs) can substantially contribute to the monitoring and performance enhancement of energy infrastructure. However, optical fiber sensor systems often are standalone solutions and do not connect to the main energy infrastructure control systems. In this paper, we propose a solution for the digitalization of an optical fiber sensor system realized by the Open Platform Communications Unified Architecture (OPC UA) protocol and the Internet of Things (IoT) platform Insights Hub. The optical fiber sensor system is based on bidirectional incoherent optical frequency domain reflectometry (biOFDR) and is used for the interrogation of fiber Bragg grating (FBG) arrays. To allow for an automated sensor identification and thus measurement procedure, an optical sensor identification marker based on a unique combination of fiber Bragg gratings (FBGs) is established. To demonstrate the abilities of the digitalized sensor network, a field test was performed in a power plant test facility of Siemens Energy. Temperature measurements of a packaged FBG sensor fiber were performed with a portable demonstrator, illustrating the system’s robustness and the comprehensive data processing stream from sensor value formation to the cloud. The realized network services promote sensor data quality, fusion, and modeling, expanding opportunities using digital twin technolog
Keywords: optical fiber sensing; fiber Bragg grating; sensor identification; digitalization; OPC UA; Internet of Things

Dimensionierung von 160 Gbit/s WDM Übertragungssystemen auf der Basis simulativer Untersuchungen - Wietfeld, André; Kaupert, T.; Striegler, Arne; Schmauß, Bernhard (Conf. Proc., 4. ITG Fachtagung Photonische Netze, ITG Fachbericht 175, 2003)
UnivIS-Import:2015-04-16:Pub.2003.tech.IE.LEH.dimens

Direction of Arrival Estimation from Secondary Surveillance RadarSignals in Presence of Hardware Imperfections - Reck, C; Berold, Ulrich; Weinzierl, Jochen; Schmidt, Lorenz-Peter (European Microwave Week / EuRAD, Amsterdam, October, 2008)
lhft_intern.bib::Reck08

Direction of Arrival Sensor Calibration based on ADS-B Airborne Position Telegrams - Reck, Christoph; Berold, Ulrich; Schür, Jan; Schmidt, Lorenz-Peter (EuMW / EuRAD, Rom, September, 2009)
This paper investigates the suitability of ADS-B airborne position messages for calibrating a direction of arrival (DOA) sensor for Secondary Surveillance Radar (SSR) signals at runtime. An ad hoc system is thereby utilized to receive, automatically select and process a statistically relevant number of ADS-B replies. It is experimentally shown that ADS-B transponders can provide a suitable calibration signal within some limitations.
UnivIS-Import:2015-04-16:Pub.2009.tech.IE.LEH.direct

Direction-sensitive ultrasonic distance sensor using multimode stimulation of a single transducer - Magori, V.; Eccardt, P.-C.; Ruser, H.; Vossiek, Martin (IEEE International Ultrasonics Symposium, 1995)
A novel ultrasonic sensor is presented which has the ability to determine the angle of incidence of sound waves by evaluating simultaneously different vibration modes of a single transducer. Since signals from the main lobe and sidelobes are discernible, side reflections can be identified and suppressed. The combining of angle and distance measurement allows a detailed characterization of object scenes. The signal evaluation is performed by an adaptive algorithm incorporating wiener filtering to improve the angular and axial resolution. In the paper, the principle of the sensor is described and results for different object scenes are presented. Investigations on level measurements in silos proved the practical applicability of the method.
UnivIS-Import:2015-04-16:Pub.1995.tech.IE.LEH.direct

Direktumwandlung solarer Energie (Stand, Ziele und Aussichten der Forschung) - Brand, Hans (1974)
lhft_intern.bib::thirty_years_LHFT_9

Distortion Analysis and Calibration of Radar Imaging Systems with Non-Ideal Antenna Arrays - Geiß, Johanna (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2023)
In the last decades, radar imaging systems have received great interest in many applications. This development is driven by their robust performance in harsh environments, where other concepts such as optical sensors fail, as well as their capability to measure both distances and velocities. Especially in the automotive field, they have become a key technology to achieve the required high safety standards for highly automated driving. The major drawback of radar sensors is their limited imaging resolution. While the radial resolution depends on the system’s bandwidth, the angular resolution depends on the total size of the available radar aperture. Therefore, most sensors are already equipped with antenna arrays on both the transmit and receiving side, yielding multiple-input multipleoutput (MIMO) systems. Nevertheless, driven by the further increasing demands on the angular resolution, the research interest now focuses among others on exploiting the car’s movement to apply synthetic aperture radar (SAR) concepts to create larger apertures. The combination of both ideas then leads to single-input multiple-output (SIMO)-SAR and MIMO-SAR systems. Antenna arrays are generally impaired by imbalances between the channels caused by phase errors, amplitude errors, as well as mutual coupling between the antennas. These errors can severely impair the radar image quality. Therefore, the arrays are calibrated prior to their operation. However, this is often done as an end-of-line calibration and may differ from the ideal calibration data after installing the sensor at its operating position. Furthermore, aging, environmental influences like temperature shifts, and physical impacts can change the channel errors over time, such that an initial calibration is usually not sufficient to maintain the peak imaging performance required in safety-critical applications. Thereby, calibration errors can become the limiting factor of the image quality, which is practically achievable, especially because advanced high-resolution reconstruction techniques generally assume ideal sensors and, thus, are often sensitive to modeling errors. Hence, frequent re-calibration is necessary for maintaining high image quality. Unfortunately, most high-quality calibration approaches require measurements to far-field targets at known angles and suppressed multipath propagation. This requires highly controlled measurement environments, such as anechoic chambers, which are not widely available. Besides this, online calibration approaches exist, which have hardly any requirements on the environment but yield only poor calibration results. Consequently, there exists a lack of high-quality calibration concepts which can be performed in arbitrary environments and do not have high requirements on a reference system. Although the limitations of currently established calibration concepts are well known, the impact of non-ideal calibration parameters on the radar image is mostly unknown. Therefore, in this thesis, first, the impact of calibration errors on radar imaging systems is analyzed thoroughly. In radar imaging concepts, which shift antenna arrays to collect spatial information, calibration errors cause periodic error patterns, leading to a deterministic formation of ghost targets in the radar image. While this effect was already observed in literature, it was never analyzed in detail. This work, for the first time, fully describes the deterministic relation and verifies the findings with measurements. It is shown, that in MIMO, SIMO-SAR, and MIMO-SAR systems, under specific conditions, the calibration error power accumulates at few, predictable positions within the radar image. The number and position of these ghost targets can be predicted without requiring knowledge about the calibration error itself. Furthermore, a set of worst-case estimates are provided, to assess the impact of different error types on the image quality. The derived theoretical principles will enable future research in the fields of calibration quality monitoring, ghost target classification, as well as both online and offline calibration. The acquired knowledge about the separation of signal and calibration error power within SAR-systems using antenna arrays allows to derive a novel calibration concept in this work. The approach is based on a SAR measurement to a sparse target scene located in the near-field of the aperture. While the number of targets is assumed known, information about their position is not required and, hence, no elaborated reference system is needed. Furthermore, no anechoic environment is required, such that the calibration can be performed in almost arbitrary environments. The approach is derived for the calibration of both SIMO and MIMO systems and its capabilities are demonstrated by measurements yielding high-quality calibration results. It, thereby, presents a possible solution to the lack of low-effort calibration concepts for frequent high-quality calibratio

Distributed air flow measurement of a 300 MVA water turbine hydro generator using a fiber-optic hot wire anemometer based on Fiber-Bragg-Grating (FBG) array - Villnow, M.; Willsch, M.; Bosselmann, T.; Schmauß, Bernhard; Hildinger, T.; Hess, T. (Conf. Proc., Sensor and Test 2010, May, 2010)
lhft_intern.bib::Villnow10

Distributed Kalman Filter for Precise and Robust Clock Synchronization in Wireless Networks - Kirsch, Fabian; Vossiek, Martin (IEEE Radio & Wireless Symposium, 2009)
A novel concept for robust and precise clock synchronization in wireless networks is introduced. The concept is based on a Kalman filter that is parallelly distributed on all network nodes. Each node uses the state estimates of other nodes to determine a local estimate of the global clock. A voting algorithm that evaluates the state estimates of several nodes is used to adjust the virtual global clock master. By avoiding any physical central clock master the distributed global clock is extremely tolerant of single nodes malfunction and no single points of failure exist in the network and protocol. In experiments with an IEEE 802.15.4 (ZigBee-PHY) network it was shown that even with a packet loss of 75% the achieved clock synchronization was always better than 4 μs. Another advantage of the realized protocol is that it requires only very low basic data traffic. Thus, the concept is ideally suited for time-synchronized sensor networks, ad hoc networks, or wireless time-triggered realtime systems. ©2009 IEEE.
UnivIS-Import:2015-04-16:Pub.2009.tech.IE.LEH.distri
Keywords: Kalman filtering; Networks; Radio communication; Synchronization

Distributed Sensing of Single Mode Fibers with Correlation Techniques - Azendorf, Florian; Sandmann, André; Eiselt, Michael; Schmauß, Bernhard (Photonische Netze - 23. ITG-Fachtagung, 2022)
In this paper, we report on the development progress of correlation-based optical time domain reflectometry (OTDR). Substituting the direct detection receiver with a coherent receiver enables to extract the phase and polarization information of the reflected signal. Furthermore, due to the mixing of a weak probe signal with a strong local oscillator the sensitivity of the receiver improved. This improvement was demonstrated by analyzing the reflection from an angled physical contact (APC) connector. To further quantify the improvements, we compare the direct detection correlation OTDR (C-OTDR) with the coherent detection correlation OTDR (CC-OTDR) with respect to the spatial and amplitude resolution.
CRIS-Team Scopus Importer:2022-09-30
Keywords: correlation techniques; distributed sensing; OTDR; phase noise

Dither-free bias control algorithm for electro-optic modulators operating at low frequencies - Castro Ayala, Pablo Roberto; Sandmann, André; Eiselt, Michael; Schmauß, Bernhard (Applied Optics, 2025)
A dither-free bias control technique for correcting bias drifts in electro-optic in-phase and quadrature modulators is presented and experimentally verified. The technique eliminates the need to apply a dither signal to the bias electrodes, and instead relies on the effects of the electrical modulation signals on the optical power. It is suited for applications where the modulation signals are of low frequency and would spectrally overlap with a conventional dither signal.
CRIS-Team Scopus Importer:2025-05-30

Doppler optical frequency domain reflectometry for remote fiber sensing - Köppel, Max; Sharma, Abhinav; Podschus, Jasper; Sundaramahalingam, Sanju; Joly, Nicolas Y.; Xie, Shangran; Russell, P. St J.; Schmauß, Bernhard (Optics Express, 2021)

DPSK Signal Regeneration Using a Nonlinear Amplifying Loop Mirror - Sponsel, Klaus; Stephan, Christian; Cvecek, Kristian; Onishchukov, Georgy; Schmauß, Bernhard; Leuchs, Gerd (Conf. Proc. OFC, Paper OThB2, March, 2007)
Power characteristics and phase functions of a NALM are investigated in simulations and experimentally, showing a phase-preserving nonlinear characteristics suitable for amplitude regeneration of phase-encoded signals. A negative power penalty of -1.5 dB was obtained. ©2006 Optical Society of America.
UnivIS-Import:2017-12-18:Pub.2007.tech.IE.LEH.dpsksi

Drahtlose Hochgeschwindigkeitskommunikation mit Regenerativer Abtastung - Carlowitz, Christian (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2018)
lhft_intern.bib::Carlowitz2018a

Dual Polarized 1-Bit Reconfigurable Reflective Unit Cell Design for Intelligent Reflective Surfaces Operating in the 5.8 GHz ISM Band - Scheder, André; Fleischmann, Johannes; Gröschel, Patrick; Vossiek, Martin (2024 54th European Microwave Conference, EuMC 2024, 2024)
In this paper the design, simulation and validation of a novel dual-polarized 1-bit reconfigurable reflective unit cell in the 5.8 GHz ISM Band used for intelligent reflective surfaces is presented. A unique feature of this design is the ability to change the phase shifts of a horizontally and a vertically polarized wave for each unit cell element separately. Therefore, it can also be used to change the direction of rotation of a circularly polarized wave. The unit cell is based on aperture-coupled patch antennas. In this design, the same patch is used for both receiving and retransmitting the signal with the corresponding phase shift. Moreover a measurement method for evaluating the performance of a reflective unit cell is presented. The simulation results show a 1-bit phase shift of 180 degrees and a low reflection losses of 0.5 dB and 1 dB of the two reflection states. The results also show a modulation efficiency of up to 90%.
CRIS-Team Scopus Importer:2024-12-13
Keywords: intelligent reflective surface (IRS); ISM band; PIN diode; polarization; reconfigurable intelligent surface (RIS); reflectarray; unit cell

Dual slope interlaced chirp sequence radar with improved target separation capability - Thurn, Karsten; Vossiek, Martin (IEEE MTT-S International Conference on Microwaves for Intelligent Mobility (ICMIM 2017), 2017)
In this paper, we introduce an approach for an improved target separation capability for the signal processing of the interlaced chirp sequence (ICS) waveform. Target velocity and range combinations can be unfavorable in some scenarios, and cannot be resolved with a single measurement. By running a second measurement with a different slope, similar to up- and downsweep for a linearly frequency-modulated continuous wave (FMCW) radar, these difficult scenarios can be resolved. Simulations and measurements with a 24 GHz radar prove the feasibility of the concept.

Dynamic Model of Spectral Hole Burning for EDFAs with 980-nm-Pumping - Holtmannspoetter, M.; Schmauß, Bernhard (Optical Fiber Communication 2011, 2011)
lhft_intern.bib::Holtmannspoetter11

Effective Conductivity Concept for Modelling Conductor Surface Roughness - Gold, Gerald; Helmreich, Klaus (Proceedings, 2014)
In the two-digit GHz-range, where the conventional skin depth decreases to the range of surface roughness, loss predicted assuming ideally smooth surfaces falls far behind measurement. A new method to treat surface roughness in field solvers is introduced which employs the concept of a frequency-dependent effective conductivity as impedance boundary condition. It is deduced by solving Maxwell's equations for the newly introduced conductivity gradient model: Comparing signal wavelength, conductor width and roughness feature size, one can conclude that a propagating wave does not "see" individual peaks and pits, but rather a "mean" plane surface, which, however, shows no abrupt border between dielectric and conductor, but a steady transition in conductivity perpendicular to the surface. Thus, roughness with the gradient model can be characterized by one single parameter: The root mean square Rq of microscopic surface height, already provided in many PCB material data sheets. This method accurately predicts measured insertion loss responses.
UnivIS-Import:2015-04-16:Pub.2014.tech.IE.c3scha.effect

Effective light coupling in reflective fiber optic distance sensors using a double-clad fiber - Werzinger, Stefan; Härteis, Lisa-Sophie; Köhler, Aaron; Engelbrecht, Rainer; Schmauß, Bernhard (International Conference on Optical Fiber Sensors (OFS), 2017)
Many fiber optic distance sensors use a reflective configuration, where a light beam is launched from an optical fiber, reflected from a target and coupled back into the fiber. While singlemode fibers (SMF) provide low-loss, high-performance components and a well-defined output beam, the coupling of the reflected light into the SMF is very sensitive to mechanical misalignments and scattering at the reflecting target. In this paper we use a double-clad fiber (DCF) and a DCF coupler to obtain an enhanced multimodal coupling of reflected light into the fiber. Increased power levels and robustness are achieved compared to a pure SMF configuration. © (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use onl
lhft_intern.bib::Werzinger2017a

Effective Mitigation of Non-linearities Using Extended Kalman Filtering for Dispersion Managed Links - Pakala, Lalitha; Schmauß, Bernhard (ITG Fachtagung Photonische Netze, 2016)
We investigate our proposed carrier phase and amplitude noise estimation (CPANE) algorithm using extended Kalman filter (EKF) for mitigation of non-linearities as well as ASE induced phase and amplitude distortions, in fully compensated periodic dispersion managed (DM) links employing standard single mode fiber (SSMF) and dispersion compensating fiber (DCF). Numerical simulations were carried out on a 224 Gb/s polarization multiplexed (PM) 16-quadrature amplitude modulation (QAM) coherent transmission system for DM links with varying launch power and transmission distance, in this study. The non-linear mitigation performance of EKF-CPANE is compared to that of conventional single step non-linear (SSNL) compensation. Numerical results show that EKF-CPANE exhibits slightly improved performance compared to SSNL compensation method. We further investigate the combined performance of these two methods by employing EKF-CPANE after SSNL compensation for the mitigation of residual non-linear distortions. As a result, an enhanced tolerance towards non-linearities of up to 2 dB can be obtained. Moreover, the combination of SSNL compensation and EKF-CPANE is quite feasible for real-time implementations since each method requires only few complex multiplications to recover one symbol.
lhft_intern.bib::Pakala2016a

Effective Negative Nonlinearity of a Nonlinear Amplifying Loop Mirror for Compensating Nonlinearity-Incuced Signal Distortions - Sponsel, Klaus; Cvecek, Kristian; Stephan, Christian; Onishchukov, Georgy; Schmauß, Bernhard; Leuchs, Gerd (Optical Communication, 2008. ECOC 2008. 34th European Conference on 21-25, 2008)
UnivIS-Import:2017-12-18:Pub.2008.tech.IE.LEH.effect

Effect of Amplitude Noise on Multi-Level Phase Regeneration - Lenz, M.; Onishchukov, G.; Schmauß, Bernhard; Leuchs, Gerd (Lasers and Electro-Optics Europe (CLEO EUROPE/EQEC), 2011 Conference on and 12th European Quantum Electronics Conference, 2011)
lhft_intern.bib::Lenz2011

Effect of embedded printed circuit board (PCB) sensors on the mechanical behavior of glass fiber-reinforced polymer (GFRP) structures - Javdanitehran, Mehdi; Hoffmann, R.; Groh, Jannis; Vossiek, Martin; Ziegmann, G. (Smart Materials and Structures, 2016)
The embedding of dielectric chipless sensors for cure monitoring into fiber-reinforced thermosets allows for monitoring and controlling the curing process and consequently higher quality in production. The embedded sensors remain after the processing in the structure. This affects the integrity of the composite structure locally. In order to investigate these effects on the mechanical behavior of the glass fiber-reinforced polymer (GFRP), sensors made on special low loss substrates are integrated into laminates with different lay-ups and thicknesses using vacuum assisted resin transfer molding (VARTM) method. In a parametric study the size of the sensor is varied to observe its influence on the strength and the stiffness of the laminates according to its lay-up and thickness. The size and orientation of the resin rich areas near sensors as well as the distortion in load bearing area as the consequences of the introduction of the sensors are investigated in conjunction with the strength of the structure. An empirical model is proposed by the authors which involves the previously mentioned factors and is used as a rapid tool for the prediction of the changes in bending and tensile strength of simple structures with embedded sensors. The methodology for model's calibration as well as the validation of the model against the experimental data of different laminates with distinct lay-ups and thicknesses are presented in this work. Mechanical tests under tensile and bending loading indicate that the reduction of the structure's strength due to sensor integration can be attributed to the size and the orientation of rich resin zones and depends over and above on the size of distorted load bearing area. Depending on the sensor's elastic modulus the stiffness of the structure may vary through the introduction of a sensor.
Keywords: analytical modelling; embedded sensor; glass fibres; mechanical properties

Effects of Different Types of Burn Wounds and its Dressings on Millimeter-Wave Images - Oppelt, Daniel; Korf, Patrick; Adametz, Julian; Groh, Jannis; Vossiek, Martin; Zhuravleva, Kristina; Goertz, Ole (Frequenz, 2018)

Efficient Bandwidth Enhanced Multirate Radar Target Simulation - Körner, Georg; Birkenhauer, Christoph; Stief, Patrick; Carlowitz, Christian; Vossiek, Martin (IEEE MTT-S International Microwave Symposium Digest, 2022)
Digital radio frequency memory (DRFM) multirate systems are digital radar target simulators that receive, digitize, delay (using memory), and retransmit a radar signal. The DRFM approach has many advantages over other radar target simulator concepts, and it has been shown that the target emulation accuracy of DRFM systems can be improved significantly by adjusting the receiver ADC and transmitter DAC to different sampling rates (multirate radar target simulator). In this paper, it is shown that the frequency and bandwidth coverage of multirate DRFM systems can be elegantly improved by applying a frequency division in the receiving path and a frequency multiplication in the transmission path and by using an adapted digital signal manipulation within the DRFM. Experimental results show that this novel technique enables lower sampling rates to be used and eases the constraints on cost and hardware complexity, thus allowing cost-efficient broadband DRFM systems.
CRIS-Team Scopus Importer:2022-09-30
Keywords: DRFM; FMCW Radar; radar target simulation; SFCW Radar

Efficient compensation of chromatic dispersion and non-linearities using logarithmic digital backward propagation in N-Channel DWDM 1.12Tbit/s DP-QPSK transmission - Asif, Rameez; Lin, Chien-Yu; Schmauß, Bernhard (Journal of Modern Optics, 2012)
We propose and numerically investigate the logarithmic step-size distribution for implementing an efficient digital backward propagation (DBP) algorithm using the split-step Fourier method (SSFM). DBP is implemented in N-channel dual-polarization quadrature-phase-shift-keying (DP-QPSK) transmission over 2000 km standard single-mode fiber (SMF) with no in-line optical dispersion compensation. This algorithm is compared with the constant step-size modified DBP (M-SSFM) algorithm in terms of efficiency, complexity and computational time. Furthermore, we investigate the same-capacity and same-bandwidth transmission systems with 14 Gbaud (GBd), 28 GBd and 56 GBd per-channel rates. The logarithmic step-size based DBP algorithm depicts efficient mitigation of chromatic dispersion (CD) and nonlinear (NL) impairment. The benefit of the logarithmic step-size is the reduced complexity and computational time for higher baud rates.
UnivIS-Import:2015-03-09:Pub.2012.tech.IE.LEH.effici
Keywords: digital backward propagation; dispersion; nonlinearities; optical communication; phase modulation; coherent receiver

Efficient Frequency Domain Chromatic Dispersion Compensation in a Coherent Polmux QPSK-Receiver - Geyer, J. C.; Fludger, C. R. S.; Duthel, T.; Schulien, C.; Schmauß, Bernhard (OSA Optics and Photonics Congress, Advanced Photonics, BGPP Topical Meeting, Karlsruhe, 21.-24. Juni, 2010)
lhft_intern.bib::Geyer10a

Efficient Synthesis of Broadband Linear Frequency-Modulated Quadrature Signals for Coherent Electro-Optical Sensor Systems - Schmidt, Marius; Carlowitz, Christian (IEEE MTT-S International Microwave Symposium Digest, 2024)
This paper presents a novel approach to efficiently generate broadband, complex baseband, linear, frequency-modulated quadrature signals for driving quadrature mach-zehnder-modulators. In contrast to conventional approaches based on high sampling rate arbitrary waveform generators, cost and complexity is significantly reduced, while coherent distance and motion sensing is retained through single-sideband optical modulation. By using two FMCW synthesizers with contrary sweep rates and frequency crossing at half sweep duration, a zero-IF frequency ramp with unlimited relative bandwidth can be generated through I/Q-downconversion. Furthermore, sweep rate and bandwidth of the frequency ramp are doubled with this method compared to a single synthesizer. for experimental verification, an FMCW signal with 10 GHz bandwidth and a ramp duration of 32 μs has been generated using two 13-18 GHz PLL-based synthesizers. Coherent optical frequency domain ranging measurements at 1550 nm with different fiber lengths exhibit similar performance in terms of resolution and sensitivity compared to a two-channel 12 GS/s laboratory-grade AWG.
CRIS-Team Scopus Importer:2024-08-16
Keywords: electro-optical modulation; FMCW radar; frequency synthesis; microwave photonics

Efficient Ultra-High Speed Communication with Simultaneous Phase and Amplitude Regenerative Sampling (SPARS) - Carlowitz, Christian; Girg, Thomas; Ghaleb, Hatem; Du, Xuan-Quang (Frequenz, 2017)
For ultra-high speed communication systems at high center frequencies above 100 GHz, we propose a disruptive change in system architecture to address major issues regarding amplifier chains with a large number of amplifier stages. They cause a high noise figure and high power consumption when operating close to the frequency limits of the underlying semiconductor technologies. Instead of scaling a classic homodyne transceiver system, we employ repeated amplification in single-stage amplifiers through positive feedback as well as synthesizer-free self-mixing demodulation at the receiver to simplify the system architecture notably. Since the amplitude and phase information for the emerging oscillation is defined by the input signal and the oscillator is only turned on for a very short time, it can be left unstabilized and thus come without a PLL. As soon as gain is no longer the most prominent issue, relaxed requirements for all the other major components allow reconsidering their implementation concepts to achieve further improvements compared to classic systems. This paper provides the first comprehensive overview of all major design aspects that need to be addressed upon realizing a SPARS-based transceiver. At system level, we show how to achieve high data rates and a noise performance comparable to classic systems, backed by scaled demonstrator experiments. Regarding the transmitter, design considerations for efficient quadrature modulation are discussed. For the frontend components that replace PA and LNA amplifier chains, implementation techniques for regenerative sampling circuits based on super-regenerative oscillators are presented. Finally, an analog-to-digital converter with outstanding performance and complete interfaces both to the analog baseband as well as to the digital side completes the set of building blocks for efficient ultra-high speed communicatio
Keywords: front-end circuits and systems; wireless RF components and systems; high-data-rate communications; superregenerative receivers

Effiziente modellbasierte Auswertung von FBG-Ketten fuer ortsaufgelöste faseroptische Temperaturmessungen - Werzinger, Stefan; Gussner, S; Schmauß, Bernhard (Workshop der ITG-Fachgruppe 5.3.1 (Modellierung photonischer Komponenten und Systeme), 2017)

E-Field Patterns of Coaxial MW Antennas for Combined Thermo-Brachytherapy - Erb, J; Engelbrecht, Rainer; Schaller, G; Roos, D; Seegenschmiedt, H; Fietkau, R; Sauer, R (1993)
lhft_intern.bib::thirty_years_LHFT_323

E-Field Patterns of Coaxial MW Antennas for Combined Thermo-Brachytherapy - Erb, J.; Engelbrecht, Rainer; Schaller, Gerhard; Ross, D.; Seegenschmiedt, Heinrich; Fietkau, Rainer; Sauer, R. (Deutsche Brachytherapie-Konferenz, 1993)
UnivIS-Import:2015-04-16:Pub.1993.tech.IE.LEH.efield

EH Modelling and Achievable Rate for FSO SWIPT Systems with Non-linear Photovoltaic Receivers - Shanin, Nikita; Ajam, Hedieh; Papanikolaou, Vasileios; Schmauß, Bernhard; Cottatellucci, Laura; Schober, Robert (Proceedings - IEEE Global Communications Conference, GLOBECOM, 2023)
In this paper, we study optical simultaneous wireless information and power transfer (SWIPT) systems, where a photovoltaic optical receiver (RX) is illuminated by ambient light and an intensity-modulated free space optical (FSO) signal. To facilitate simultaneous information reception and energy harvesting (EH) at the RX, the received optical signal is first converted to an electrical signal, and then, its alternating current (AC) and direct current (DC) components are separated and utilized for information decoding and EH, respectively. By accurately analysing the equivalent electrical circuit of the photovoltaic RX, we model the current flow through the photovoltaic p-n junction in both the low and high input power regimes using a two-diode model of the p-n junction and we derive a closed-form non-linear EH model that characterizes the harvested power at the RX. Furthermore, taking into account the non-linear behaviour of the photovoltaic RX on information reception, we derive the optimal distribution of the transmit information signal that maximizes the achievable information rate. The proposed EH model is validated by circuit simulation results. Furthermore, we compare with two baseline models based on maximum power point (MPP) tracking at the RX and a single-diode p-n junction model, respectively, and demonstrate that in contrast to the proposed EH model, they are not able to fully capture the non-linearity of photovoltaic optical RXs. Finally, our numerical results highlight that the proposed optimal distribution of the transmit signal yields significantly higher achievable information rates compared to uniformly distributed transmit signals, which are optimal for linear optical information RX
CRIS-Team Scopus Importer:2024-12-16

EH Modelling and Achievable Rate for FSO SWIPT Systems with Non-Linear Photovoltaic Receivers - Shanin, Nikita; Ajam, Hedieh; Papanikolaou, Vasilis K.; Schmauß, Bernhard; Cottatellucci, Laura; Schober, Robert (Proceedings - IEEE Global Communications Conference, GLOBECOM, 2023)
In this paper, we study optical simultaneous wireless information and power transfer (SWIPT) systems, where a photo-voltaic optical receiver (RX) is illuminated by ambient light and an intensity-modulated free space optical (FSO) signal. To facilitate simultaneous information reception and energy harvesting (EH) at the RX, the received optical signal is first converted to an electrical signal, and then, its alternating current (AC) and direct current (DC) components are separated and utilized for information decoding and EH, respectively. By accurately analysing the equivalent electrical circuit of the photovoltaic RX, we model the current flow through the photovoltaic p-n junction in both the low and high input power regimes using a two-diode model of the p-n junction and we derive a closed-form non-linear EH model that characterizes the harvested power at the RX. Furthermore, taking into account the non-linear behaviour of the photovoltaic RX on information reception, we derive the optimal distribution of the transmit information signal that maximizes the achievable information rate. The proposed EH model is validated by circuit simulation results. Furthermore, we compare with two baseline models based on maximum power point (MPP) tracking at the RX and a single-diode p-n junction model, respectively, and demonstrate that in contrast to the proposed EH model, they are not able to fully capture the non-linearity of photovoltaic optical RXs. Finally, our numerical results highlight that the proposed optimal distribution of the transmit signal yields significantly higher achievable information rates compared to uniformly distributed transmit signals, which are optimal for linear optical information RXs.
CRIS-Team Scopus Importer:2024-12-16

Eigenschaften des Lasers und seine Anwendung in der Endoskopie - Brand, Hans; Bodem, F; Reidenbach, H; Fruehmorgen, P (Sonderdruck aus "'Forschritt der Endoskopie"', Bd. 6, 1975)
lhft_intern.bib::thirty_years_LHFT_14

Eigenschaften und Einsatzmoeglichkeiten eines flexiblen Kunststoff-Lichtleiters im Bereich hoeherer Lichtleistungen zur Photokoagulation - Reidenbach, H; Bodem, F; Fruehmorgen, P; Brand, Hans (Biomedizinische Technik. Biomedical engineering, 1975)
lhft_intern.bib::thirty_years_LHFT_20

Eigenschaften und Grenzen optischer Fasern durch lineare und nichtlineare Effekte - Engelbrecht, Rainer (Bayerisches Laserzentrum, Workshop Optische Fasern - Leistungsübertrag von UV bis IR, 2008)
UnivIS-Import:2015-04-16:Pub.2008.tech.IE.LEH.eigens

Eine lichtgesteuerte Wellenleiter-Antenne aus Halbleitermaterial - Brand, Hans; Ermert, H; Karg, R (Mikrowellen-Magazin, 5, 1977)
lhft_intern.bib::thirty_years_LHFT_70

Ein Mikrowellensensornetzwerk zur räumlichen Fahrzeug-zu-Fahrzeug- und Fahrzeug-zu-Infrastruktur-Ortung (A Wireless Sensor Network for Spacial Vehicle-to-vehicle and Vehicle-to-infrastructure Localization) - Ebelt, Randolf; Millner, Hendrik; Vossiek, Martin (Technisches Messen, 2010)
lhft_intern.bib::Ebelt2010

Ein selbstorganisierendes Sensornetz mit Lokalisierungsfunktion - Ebelt, Randolf; Vossiek, Martin (Fraunhofer IIS - Vortragsreihe Faszination Technik, 2012)
lhft_intern.bib::Ebelt2012a

Ein Ultraschall-Mehrwandlersystem zur lageunabhängigen Objekterkennung für die industrielle Automation - Vossiek, Martin (VDI-Verlag, 1996)
UnivIS-Import:2015-04-02:Pub.1996.tech.IE.LEH.einult

Ein Verfahren zur Ermittlung komplexer Dielektrizitätskonstantenduenner Folien im Millimeterwellenbereich - Schmidt, Lorenz-Peter; Hofmann, H (AEÜ - International Journal of Electronics and Communications, 1979)
lhft_intern.bib::Schmidt79

Electronic mitigation of fiber transmission impairments in 100Gbit/s WDM phase encoded transmission with optical add-drop multiplexers - Asif, Rameez; Lin, Chien-Yu; Usman, Muhammad; Holtmannspötter, Michael; Schmauß, Bernhard (Photonics North Conference (SPIE Proceedings), 2011)
Digital Backward Propagation (DBP) algorithm for mitigating fiber dispersion and non-linearities based on modified non-iterative symmetric split-step Fourier method (M-SSFM) is implemented and numerically evaluated. The algorithm is modified by shifting the calculation point of non-linear operator (r) together with the optimization of dispersion (D) and non-linear coefficient (γ) to get the optimum system performance. DBP is evaluated for 10x10Gbit/s wavelength division multiplexed (WDM) system (a total transmission capacity of 100Gbit/s) with RZ-DQPSK encoded signals over a transmission length of 1600km standard single mode fiber (SMF) with no in-line optical dispersion compensation. Furthermore, we quantify the impact of optical add-drop multiplexers (OADMs) in the transmission link. Modification of DBP parameters and bandwidth of optical filters associated with OADMs give significant improvement in the system performance. © (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
lhft_intern.bib::Asif11a

Enabling Technologies for Efficient 100-Gb/s Wireless Communication Systems [From the Guest Editor's Desk] - Carlowitz, Christian; Kaneda, Noriaki (IEEE Microwave Magazine, 2023)
CRIS-Team Scopus Importer:2024-12-16

End face coupling as detachable connection of dielectric waveguides at 75 GHz and 300 GHz - Weinzierl, Jochen; Schmidt, Lorenz-Peter; Hörster, Eva; et al. (Conference Digest of the 2004 Joint 29th International Conference on Infrared and Millimeter Waves and 12th International Conference on Terahertz Electronics, 2004)
End face coupling of rectangular dielectric waveguides at 75 GHz and 300 GHz is presented as a new, low-loss and powerful method for novel switching and multiplexing applications of MMW and SMMW signals. The coupling of the waveguides has been investigated, designed and optimized by extensive numerical field simulations and experimental verification at both frequencies. © 2004 IEEE.

End-to-End Learning for Human Pose Estimation from Raw Millimeter Wave Radar Data - Müller, Jonas; Krauß, Daniel; Engel, Lukas; Vossiek, Martin; Eskofier, Björn; Dorschky, Eva (Asilomar Conference on Signals, Systems, and Computers, 2024)

Energie und Klima - Ein Blick in die Zukunft - Brand, Hans; Hosemann, Gerhard; Riedle, Klaus (FAU University Press, Erlangen, 2013)
lhft_intern.bib::Brand2013b

Enhanced Mode Selectivity of Directional Couplers with Multimode Optical Fibres Using Different Index Matching Oils - Schmauß, Bernhard (AEÜ - International Journal of Electronics and Communications, 1992)
lhft_intern.bib::thirty_years_LHFT_293

Enhanced seismic sensing based on epoxy waveguide Bragg gratings - Hessler, Steffen; Bott, Patrick; Kefer, Stefan; Girschikofsky, Maiko; Schmauß, Bernhard; Hellmann, Ralf (Proceedings of SPIE - The International Society for Optical Engineering, 2019)
We report on the fabrication process and the application potential of epoxy-based waveguide Bragg grating sensors on low-modulus polymer substrates for low-cost environmental seismic sensing purposes. EpoCore photoresist channel waveguides are fabricated on a highly flexible TPX polymethylpentene polyolefin substrate by means of standard i-line photolithography. Bragg gratings are permanently inscribed into the strip waveguides by KrF excimer laser irradiation using commercially available phase masks. From these raw sensor chips, a linear accelerometer sensitivity of 107 pm/g in a broadband detection range of at least 0.025 - 15 g could be observed. The enhanced seismic sensing capabilities of the Bragg grating sensor scheme are demonstrated by the use of a simple spring mass system.
CRIS-Team Scopus Importer:2020-02-21
Keywords: Accelerometer; Bragg grating; EpoCore; Polymers; Seismometer

Enhanced Transmission Performance Using Digital Back Propagation and Extended Kalman Filtering for Dispersion Unmanaged Links - Pakala, Lalitha; Schmauß, Bernhard (Signal Processing in Photonics and Communications, 2016)
The transmission performance of extended Kalman filtering (EKF) significantly outperforms one-step-per-span optimized digital back propagation (DBP). At the expense of few DBP steps deployed prior to EKF yields further enhanced non-linear tolerance.
lhft_intern.bib::Pakala2016d

Entwicklung von miniaturisierten E-Feldsonden zur Vermessung von Hyperthermie-Applikatoren - Engelbrecht, Rainer; Erb, J; Schaller, G (1993)
lhft_intern.bib::thirty_years_LHFT_326

Entwicklung von miniaturisierten E-Feldsonden zur Vermessung von Hyperthermie-Applikatoren - Engelbrecht, Rainer; Erb, J.; Schaller, Gerhard (24. Wissenschaftliche Tagung der Deutschen Gesellschaft für Medizinische Physik (DGMP), 1993)
UnivIS-Import:2015-04-16:Pub.1993.tech.IE.LEH.entwic

Erratum: Doppler optical frequency domain reflectometry for remote fiber sensing (Opt. Express (2021) 29: 10 (14615-14629) DOI: 10.1364/OE.421842) - Köppel, Max; Sharma, Abhinav; Podschus, Jasper; Sundaramahalingam, Sanju; Joly, Nicolas Y.; Xie, Shangran; Russell, Philip St. J.; Schmauß, Bernhard (Optics Express, 2021)
In this erratum we correct a typographical error in Eq. (10) of our recently published paper [1], in which the negative sign of the second product enclosed in squared brackets in the denominator is wrong. The correct equation should be: (FormulaPresented).
CRIS-Team Scopus Importer:2021-07-30

Erratum: Hypersensitive H2 sensor based on polymer planar Bragg gratings coated with Pt-loaded WO3–SiO2 (Optics Letters (2020) 45 (3601) DOI: 10.1364/OL.395341) - Kefer, Stefan; Dai, Jixiang; Yang, Minghong; Schmauß, Bernhard; Hellmann, Ralf (Optics Letters, 2020)
We present an erratum to our Letter [Opt. Lett. 45, 3601 (2020)]. Labeling errors in two figures and an incorrect sentence are revised. The corrections have no influence on the conclusions of the original Letter. In Figs. 2(b) and 4 of [1], the respective labeling of TE andTM reflection peak is corrected, as it is interchanged in the original publication. According to Fig. 4, the TM peak’s wavelength shift is approximately 5% greater than that of the TE reflection signal. This circumstance is also interchanged in the original Letter [1].
CRIS-Team Scopus Importer:2021-04-19

Erste erfolgreiche endoskopische Laser-Photokoagulationstherapie im Magen-Darm-Trakt des Menschen - Bodem, F; Reidenbach, H; Brand, Hans; Fruehmorgen, P; Demling, L; Kaduk, B (Laser & Photonics Reviews, 1975)
lhft_intern.bib::thirty_years_LHFT_23

Erste erfolgreiche endoskopische Laser-Photokoagulationstherapie im Magen-Darm-Trakt des Menschen - Fruehmorgen, P; Demling, L; Bodem, F; Reidenbach, H; Brand, Hans; Kaduk, (Deutsche Medizinische Wochenschrift, 1975)
lhft_intern.bib::thirty_years_LHFT_22

Erzeugung von 3D-Funktionsstrukturen fuer Hochfrequenzanwendungen durch Druckverfahren - Ankenbrand, Markus; Franke, Jörg; Lomakin, Konstantin; Pavlenko, Tatiana; Sippel, Mark; Gold, Gerald; Weidner, T; Weiß, D; Helmreich, Klaus (PLUS - Produktion von Leiterplatten und Systemen, 2018)

Erzeugung von 3D-Funktionsstrukturen für Hochfrequenzanwendungen durch Druckverfahren - Helmreich, Klaus; Gold, Gerald (PLUS - Produktion von Leiterplatten und Systemen, 2016)
UnivIS-Import:2017-07-10:Pub.2016.tech.IE.c3scha.erzeug

Establishment and evaluation of a sensor-based method to assess hand function in patients with rheumatoid arthritis - Coppers, Birte; Phutane, Uday; Berisha, Dardan; Tascilar, Koray; Kleyer, Arnd; Simon, David; Bräunig, Johanna; Penner, Johann; Vossiek, Martin; Schönau, Verena; Heinrich, Simon; Bayat, Sara; et al. (conference, World Biomechanics Congress 2022, 2022)

Estimation of frequency conversion efficiency of THz devices using a ballistic electron wave swing circuit model - Schildbach, Christian; Ong, Duu Sheng; Hartnagel, Hans; Schmidt, Lorenz-Peter (Semiconductor Science and Technology, 2016)
The ballistic electron wave swing device has previously been presented as a possible candidate for a simple power conversion technique to the THz -domain. This paper gives a simulative estimation of the power conversion efficiency. The harmonic balance simulations use an equivalent circuit model, which is also derived in this work from a mechanical model. To verify the validity of the circuit model, current waveforms are compared to Monte Carlo simulations of identical setups. Model parameters are given for a wide range of device configurations. The device configuration exhibiting the most conforming waveform is used further for determining the best conversion efficiency. The corresponding simulation setup is described. Simulation results implying a conversion efficiency of about 22% are presente
lhft_intern.bib::Schildbach2016

Evaluation and Characterization of 3D Printed Pyramid Horn Antennas utilizing different Deposition Techniques for Conductive Material - Lomakin, Konstantin; Pavlenko, Tatiana; Ankenbrand, Markus; Sippel, Mark; Ringel, Johannes; Scheetz, Matthias; Klemm, Tobias; Gräf, Daniel; Helmreich, Klaus; Franke, Jörg; Gold, Gerald (IEEE Transactions on Components, Packaging and Manufacturing Technology, 2018)
This paper evaluates different metal deposition approaches for a two-staged additive manufacturing (AM) process for 3-D horn antennas, divided into the deposition of plastic and conductive material. The demonstrated fabrication workflow allows for antennas of low cost and low weight and, therefore, demonstrates the vast benefit of AM. The comparison of a commercially available cast aluminum horn to the fabricated prototypes reveals a deviation of up to 3 dB in terms of transmission losses in copolarization over a distance of 1.85 m. Cross-polarization measurements are presented revealing a larger variation among the different metallization approaches. The results shown in this paper demonstrate a successful application of AM in radio frequency engineering. Moreover, one of the presented approaches makes use of only 3-D printing systems and is, therefore, potentially suitable for totally automated manufacturin
lhft_intern.bib::Lomakin2018g

Evaluation of Automotive Radar Simulation Tools for Adverse Weather Conditions: A Comparative Analysis of Real Measurement, HFSS and Monte-Carlo GO Methods - Wachtel, Diogo; Schüßler, Christian; Von Dem Bussche, Tetmar; Rothmeier, Thomas; Vossiek, Martin; Huber, Werner (Proceedings of the IEEE Radar Conference, 2024)
Weather-related crashes continue to be a significant cause of fatalities and injuries each year in the automotive field, with adverse weather conditions affecting such properties as the radar detection range, vehicle speed, and detection accuracy. Advanced driver assistance systems (ADAS) rely on clear and accurate environmental perception; automotive radar sensors play a crucial role in these systems, especially in challenging weather. Simulation has emerged as a valuable tool to validate driving functions and sensors in a virtual environment, providing the ability to simulate critical scenarios and adjust weather conditions reproducibly. However, the simulation tool requires validation against real-world scenarios to ensure reliability. Creating a near-to-reality radar model is complex because of the various factors influencing electromagnetic wave propagation, such as surface roughness, temperature, material composition, and thickness. These factors contribute to the complexity of multi-path propagation in radar simulations. This study conducted real measurements and simulations with a high-frequency structure simulator (HFSS) and a Monte-Carlo geometrical optics (Monte-Carlo GO) implementation on various dry and wet samples. The results were calibrated and compared, and they revealed that HFSS moderately outperformed the Monte-Carlo GO method's overall accuracy; nevertheless, the latter requires less computing capability and fewer triangles compared with HFSS; therefore, it may still be a vital choice for specific applications that require a lot of simulation data. Furthermore, the results showed that some materials change reflectivity because of humidity, and they must be adjusted in the simulations.
CRIS-Team Scopus Importer:2024-07-05
Keywords: FMCW Radar; Material Properties

Evaluation of correlated digital back propagation and extended Kalman filtering for non-linear mitigation in PM-16-QAM WDM systems - Pakala, Lalitha; Schmauß, Bernhard (SPIE Photonics West OPTO, 2017)
We investigate the individual and combined performance of correlated digital back propagation (CDBP) and extended Kalman filtering (EKF) in mitigating inter and intra-channel non-linearities in wavelength division multiplexed (WDM) systems. The afore-mentioned algorithms are verified through numerical simulations on 28 Gbaud polarization multiplexed (PM) 16-quadrature amplitude modulation (16-QAM) 9-channel WDM system with 50 GHz spacing. A single channel CDBP with one-step-per-span based on asymmetric split step Fourier method (A-SSFM) with optimized non-linear coefficient has been employed. We also study an amplitude dependent optimization (AO) of the non-linear coefficient for CDBP which shows an improvement of ≈ 0.8 dB compared to the conventional optimized CDBP, in the non-linear regime. Moreover, our proposed carrier phase and amplitude noise estimation (CPANE) algorithm based on EKF outperforms AO-CDBP in both linear and non-linear regimes with an enhanced performance besides significantly reduced complexity. We further investigate the combined performance of AO-CDBP and EKF which results in an enhanced non-linear tolerance at the expense of increased computational cost trading off to the number of required CDBP steps per span. Furthermore, we also analyze the impact of cross phase modulation (XPM) on the combined performance of AO-CDBP and EKF by varying the number of WDM channels. Numerical results show that the obtained gain from employing AO-CDBP prior to EKF reduces with increasing effects of XPM. Additionally, we also discuss the computational complexity of the aforementioned algorithms. © (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
lhft_intern.bib::Pakala2017d

Evaluation of Correlative Coding and DP-16QAM N-channel 112 Gbit/s Coherent Transmission: Digital Non-linear Compensation Perspective - Asif, Rameez; Lin, Chien-Yu; Holtmannspötter, Michael; Schmauß, Bernhard (Proceedings of the 38th European Conference and Exhibition on Optical Communication (ECOC), 2012)
UnivIS-Import:2017-12-18:Pub.2012.tech.IE.LEH.evalua

Evaluation of correlative coding and DP-16QAM n-channel 112Gbit/s coherent transmission: digital non-linear compensation perspective. - Asif, Rameez; Lin, Chien-Yu; Holtmannspötter, Michael; Schmauß, Bernhard (Optics Express, 2013)
We numerically report on the complexity reduction of digital backward propagation (DBP) by utilizing correlative encoded transmission (dual-polarization quadrature duobinary) at a bit-rate of 112Gbit/s over 1640km fiber link. The single channel (N=1) and multi-channel (N=10) transmission performances are compared in this paper. In case of multi-channel system, 10 transmitters are multiplexed with 25GHz channel spacing. The fiber link consists of Large A(eff) Pure-Silica core fiber with 20 spans of 82km each. No in-line optical dispersion compensator is employed in the link. The system performances are evaluated by monitoring the bit-error-ratio and the forward error correction limit corresponds to bit-error-ratio of 3.8×10(-3). The DBP algorithm is implemented after the coherent detection and is based on the logarithmic step-size based split-step Fourier method. The results depict that dual-polarization quadrature duobinary can be used to transmit 112Gbit/s signals with an spectral efficiency of 4-b/s/Hz, but at the same time has a higher tolerance to nonlinear transmission impairments. By utilizing dual-polarization quadrature duobinary modulation, comparative system performance with respect to dual-polarization 16-quadrature amplitude modulation transmission can be achieved with 60% less computations and with a step-size of 205km.

Evaluation of Crosstalk between Additively Manufactured Slotted Waveguides in mmWave Applications - Lomakin, Konstantin; Alhasson, Saif; Gold, Gerald (European Microwave Conference (EuMC), 2022)

Evaluation of marker-based motion capturing to charactherize basic hand movements in rheumatic patients - Coppers, Birte; Heinrich, Simon; Phutane, Uday; Berisha, Dardan; Tascilar, Koray; Kleyer, Arnd; Simon, David; Bräunig, Johanna; Penner, Johann; Vossiek, Martin; Schönau, Verena; Bayat, Sara; et al. (27th Congress of the European Society of Biomechanics, 2022)

Evaluation of Non-linear Phase Noise in DPSK Transmission for Different Link Designs - Lin, Chien-Yu; Holtmannspötter, Michael; Asif, Rameez; Schmauß, Bernhard (Physics Procedia, 2010)
lhft_intern.bib::Lin10a

Evaluation of Optical and Radar Based Motion Capturing Technologies for Characterizing Hand Movement in Rheumatoid Arthritis — A Pilot Study - Phutane, Uday; Liphardt, Anna-Maria; Bräunig, Johanna; Penner, Johann; Klebl, Michael; Vossiek, Martin; Kleyer, Arnd; Schett, Georg; Leyendecker, Sigrid (Sensors, 2021)
In light of the state-of-the-art treatment options for patients with rheumatoid arthritis (RA), a detailed and early quantification and detection of impaired hand function is desirable to allow personalized treatment regiments and amend currently used subjective patient reported outcome measures. This is the motivation to apply and adapt modern measurement technologies to quantify, assess and analyze human hand movement using a marker-based optoelectronic measurement system (OMS), which has been widely used to measure human motion. We complement these recordings with data from markerless (Doppler radar) sensors and data from both sensor technologies are integrated with clinical outcomes of hand function. The technologies are leveraged to identify hand movement characteristics in RA affected patients in comparison to healthy control subjects, while performing functional tests, such as the Moberg-Picking-Up Test. The results presented discuss the experimental framework and present the limiting factors imposed by the use of marker-based measurements on hand function. The comparison of simple finger motion data, collected by the OMS, to data recorded by a simple continuous wave radar suggests that radar is a promising option for the objective assessment of hand function. Overall, the broad scope of integrating two measurement technologies with traditional clinical tests shows promising potential for developing new pathways in understanding of the role of functional outcomes for the RA pathology.<br

Evaluation of Ultrasonic Sensor Signals Using Fuzzy Logic - Vossiek, Martin; Eccardt, P.-C.; Magori, V. (Symposium on Acoustical Imaging, 1995)
UnivIS-Import:2015-04-16:Pub.1995.tech.IE.LEH.evalua

Evaluation of Ultrasonic Sensor Signals Using Fuzzy Logic - Vossiek, Martin; Eccardt, P; Magori, V (Accoustical Imaging, 1996)
Novel ultrasonic sensor systems are introduced which demonstrate the use and strength of fuzzy logic for evaluating ultrasonic signals. As one application the recognition of objects and situations by ultrasonic means will be discussed. To inspect printed circuit boards the correlation function of the actual signal from a board under test and the reference signal is evaluated using fuzzy logic. The sensor system does not only recognize assembly defects with high resolution and high reliability, but also classifies the kind of defects. Another application of fuzzy logic for ultrasonic sensor systems is the level measurement of liquids or bulk materials. Employing fuzzy logic, rather than Boolean, for discriminating the echo of the material surface, a high performance of the sensor in critical environment conditions has been achieved. Besides the basic principles of processing ultrasonic signals with fuzzy methods the paper presents implementations of the fuzzy algorithms on a fuzzy coprocessor (SAB 81C99A) or a digital signal processo
lhft_intern.bib::Vossiek1996b

Evaluation of Ultrasonic Sensor Signals Using Fuzzy Logic - Vossiek, Martin; Eccardt, P; Magori, V (Symposium on Acoustical Imaging, 1996)
Novel ultrasonic sensor systems are introduced which demonstrate the use and strength of fuzzy logic for evaluating ultrasonic signals. As one application the recognition of objects and situations by ultrasonic means will be discussed. To inspect printed circuit boards the correlation function of the actual signal from a board under test and the reference signal is evaluated using fuzzy logic. The sensor system does not only recognize assembly defects with high resolution and high reliability, but also classifies the kind of defects. Another application of fuzzy logic for ultrasonic sensor systems is the level measurement of liquids or bulk materials. Employing fuzzy logic, rather than Boolean, for discriminating the echo of the material surface, a high performance of the sensor in critical environment conditions has been achieved. Besides the basic principles of processing ultrasonic signals with fuzzy methods the paper presents implementations of the fuzzy algorithms on a fuzzy coprocessor (SAB 81C99A) or a digital signal processo
lhft_intern.bib::Vossiek1995a

Exceeding Hardware Confined Bandwidth in Incoherent Optical Frequency Domain Reflectometry - Härteis, Lisa-Sophie; Renner, Esther; Schmauß, Bernhard (2022 IEEE Photonics Conference, IPC 2022 - Proceedings, 2022)
Bidirectional incoherent optical frequency domain reflectometry exhibits confined spatial resolution through the Mach-Zehnder Modulator's restricted bandwidth in backward direction. We propose hardware confined bandwidth exceedance by utilizing digital signal processing and therewith improve the spatial resolution by a factor of four.
CRIS-Team Scopus Importer:2024-12-16
Keywords: electrical bandwidth; fiber Bragg gratings; OFDR; signal processing; spatial resolution

Exchanging Bandwidth with Aperture Size in Wireless Indoor Localization - or why 5G/6G Systems with Antenna Arrays can Outperform UWB Solutions - Sippel, Erik; Geiß, Johanna; Brückner, Stefan; Gröschel, Patrick; Hehn, Markus; Vossiek, Martin (IEEE Open Journal of Vehicular Technology, 2021)
The localization of wireless devices in indoor scenarios presents a major challenge because of multipath propagation. Hence, the majority of the research community has focused on increasing the available bandwidth of localization systems, leading to the emergence of the ultra wide band (UWB) radar. However, the hardware implementation of UWB transceivers is challenging itself and, hence, their utilization in commercial low-cost wireless devices is not to be expected in the near future. Hence, instead of evaluating frequency dependent phases via UWB, the measurement of spatially distributed phases represents a valuable alternative. Therefore, this article presents a comparison of phase-difference-of-arrival (PDOA) and time-of-arrival (TOA) systems. For this purpose, we compare the measurement sensitivity, the effects of multipath propagation, and the hardware complexity. Based on the results, the applicability of typical position estimators is discussed. Thereby, we argue that PDOA-based localization with large receiver arrays appears to be the better choice to localize wireless devices, because it enables highly accurate positioning using narrow band signals without elaborated transmitter-receiver synchronization. To validate this, indoor localization measurements are presented and compared with UWB results in extant literatur

Excitation of gap plasmonic wavguides by nano antennas - Schmauß, Bernhard; Weng, J.; Banzer, P.; Ploss, D.; Kriesch, A.; Peschel, Ulf (Conference on Lasers and Electro-Optics CLEO, Paper QMF1, San Jose, May, 2010)
We experimentally demonstrate the excitation of plasmonic gap waveguides by nano antennas. The excitation is shown to be both spatially and spectrally dependent which can potentially be used for the selective excitation of plasmonic nanostructure
lhft_intern.bib::Schmauss10

Experimental Characterization of a Wide Angle Lens for Millimeter-Wave Imaging - Richter, Jürgen; Simon, Alexander; Schmidt, Lorenz-Peter (Proc. of the IEEE International Antennas and Propagation Symposium, Washington D.C., July, 2005)
The field of view of wide angle dielectric lens antennas for focal plane arrays is mainly limited due to astigmatic aberrations which are often not taken into consideration even in more complex coma-corrected lens designs with two aspheric surfaces. This paper describes an efficient compact range setup for the measurement of high-gain lens antennas in small antenna chambers and presents a thorough experimental study of the effects of astigmatism and feed displacement/misalignment on the pattern degradation for large scanning angles. An experimentally derived method to minimize these aberrations is explained, resulting in a fairly constant beam quality with a maximized gain over a large field of view of 40°. © 2005 IEEE.
UnivIS-Import:2015-04-16:Pub.2005.tech.IE.LEH.experi_7

Experimental Characterization of a Wide Angle Lens for Millimeter-WaveImaging, Washington, DC, USA, July - Richter, J; Simon, A; Schmidt, Lorenz-Peter (APS-Symposium, Washington, DC, USA, July, 2005)
lhft_intern.bib::richter05

Experimental Comparison of All-Optical Phase-Preserving Amplitude Regeneration Techniques - Endres, D.; Stephan, C.; Sponsel, K.; Onishchukov, G.; Schmauß, Bernhard; Leuchs, Gerd (12th International Conf. on Digital Object Identifier (ICTON), Munich, June, 2010)
lhft_intern.bib::Endres10

Experimental Comparison of the Frequency Shift of Brillouin Scattering and the Raman Gain measured in short Fibers with different Germanium content - Engelbrecht, Rainer; Hagen, J.; Polster, M.; Albrecht, C. (Conference on Lasers and Electrooptics Europe, CLEO Europe 2005, Munich, June, 2005)
In this paper, we measured the germanium concentration of shorter fiber samples by the frequency shift DeltafSBSof stimulated Brillouin scattering (SBS) and Raman gain measurement. It is concluded that the measurement of the SBS frequency shift DeltafSBS is an appropriate means to identify fibers with a high Raman gain even with only a few meters of a fiber sample
UnivIS-Import:2015-04-16:Pub.2005.tech.IE.LEH.experi

Experimental cross-polarization detection of coupling far-field light to highly confined plasmonic gap modes via nanoantennas - Wen, J.; Banzer, Peter; Kriesch, Arian; Ploss, Daniel; Schmauß, Bernhard; Peschel, Ulf (Applied Physics Letters, 2011)
We experimentally demonstrate the coupling of far-field light to highly confined plasmonic gap modes via connected nanoantennas. The excitation of plasmonic gap modes is shown to depend on the polarization, position, and wavelength of the incident beam. Far-field measurements performed in crossed polarization allow for the detection of extremely weak signals re-emitted from gap waveguides and can increase the signal-to-noise ratio dramatically.
lhft_intern.bib::Wen11

Experimental Investigation of a Modified NOLM for Phase-Encoded Signal Regeneration - Cvecek, Kristian; Onishchukov, Georgy; Sponsel, Klaus; Striegler, Arne; Schmauß, Bernhard (IEEE Photonics Technology Letters, 2006)
We experimentally investigate the amplitude and phase transfer characteristics of a modified nonlinear optical loop mirror (NOLM) with a directional attenuator (DA-NOLM) optimized for differential phase-shift keying signal regeneration. The results show that the phase relation is preserved in the setup and thus the DA-NOLM is suitable for amplitude regeneration of phase-shift-keyed signals. © 2006 IEEE.
UnivIS-Import:2015-04-14:Pub.2006.tech.IE.LEH.experi
Keywords: 2R regeneration; All-optical regeneration; Differential phase-shift keying (DPSK); Nonlinear optical loop mirror (NOLM)

Experimental Investigation of the Spectral Behaviour of a Short Raman Fiber Laser and a Raman MOPA - Hagen, Johannes; Siekiera, Alexander; Engelbrecht, Rainer; Schmauß, Bernhard (Europhoton 2006, Pisa, 10.-15. Sept., 2006)
UnivIS-Import:2015-04-16:Pub.2006.tech.IE.LEH.experi_6

Experimental Phase Center Determination of Millimeterwave Antennas using Scaled Models at X-Band Frequencies - Richter, Jürgen; Biber, Stephan; Schmidt, Lorenz-Peter; Simon, J. (AMTA Europe Symposium Munich, May, 2006)
UnivIS-Import:2015-04-16:Pub.2006.tech.IE.LEH.experi_8

Experimental Results on 10 Bbit/s Data Transmission Using DifferentModulation Schemes - Loquai, Sven; Kruglov, R.; Schmauß, Bernhard; Winkler, F.; Vinogradov, J.; Ziemann, O.; Hartl, E. (Polymer Optical Fiber Conference, 2013)
lhft_intern.bib::Loquai2013d

Experimental Simulation of Artifacts in SAR-Patterns in Case of Maladjusted Superfical Microwave Waveguide Applicators - Erb, J; Engelbrecht, Rainer; Schaller, G; Seegenschmiedt, H; Fietkau, R; Bolmsjoe, M; Sauer, R (1993)
lhft_intern.bib::thirty_years_LHFT_304

Experimental Simulations of Artifacts in Case of Maladjusted Superficial Microwave Waveguide Applicators - Erb, J; Engelbrecht, Rainer; Schaller, G; Klautke, G; Mueller, R; Seegenschmiedt, H; Sauer, R; Bolmsjoe, M (1993)
lhft_intern.bib::thirty_years_LHFT_339

Experimental Simulations of Artifacts in Case of Maladjusted Superficial Microwave-Waveguide-Applicators - Erb, J.; Engelbrecht, Rainer; Schaller, Gerhard; Klautke, G.; Müller, R. G.; Seegenschmiedt, Heinrich; Sauer, R.; Bolmsjö, M. (41st Ann. Meeting of the Radiation Research Society and the 13th Annual Meeting of the North American Hyperthermia Society, 1993)
UnivIS-Import:2015-04-16:Pub.1993.tech.IE.LEH.experi

Experimental Verification of a Digital Delay Transponder Used as an In-Ice Synthetic Aperture Radar Reference Target - Stelzig, Michael; Benedikter, Andreas; Horn, Ralf; Jaeger, Marc; Keller, Martin; Scheiber, Rolf; Haberberger, Niklas; Krabbe, Lena; Krieger, Gerhard; Vossiek, Martin (2023 53rd European Microwave Conference (EuMC), 2023)
Low-frequency radar systems offer great potential to support navigation systems of exploratory ice-penetrating probes for cryospheric applications. Due to the comparably small radar cross-section (RCS) of such probes, transponder-like functionalities are mandatory to realise an increased RCS for a reliable in-ice detection and localisation of these probes. To support such applications, a miniaturised monostatic digital delay transponder was developed and tested in a measurement scenario with an airborne synthetic aperture radar (SAR) sensor on an alpine glacier.<br
Keywords: Radar cross-sections; Prototypes; Tomography; Signal processing; Delays; Radar applications; Transponders; Pulse compression radar; radar cross-section (RCS); synthetic aperture radar (SAR); transponder

Experimental Verification of Particle-in-cell Simulation Results concerning Capacitive Pickup Devices - Ruf, Marcel; Schmidt, Lorenz-Peter; Setzer, St. (Proceedings of DIPAC09, 2009)
For beam position monitoring purposes, three different approaches have been applied to investigate and compare pickup button and electron beam spectrum characteristics. Results on this simulative approach are presented. Induced pickup currents have been calculated both with an analytical and a numerical method. An experimental validation of these simulation results has been conducted with the 6-MeV electron beam from a linear accelerator for medical purposes. The measurements were conducted under non-vacuum conditions. Good agreement between particle-in-cell simulation and experimental data was achieved concerning pickup power spectral distribution and dependence from beam current and beam displacements although non-negligible electron spread during air passage of the electron beam cannot be avoided.
UnivIS-Import:2015-04-16:Pub.2009.tech.IE.LEH.experi

Experiments Characterizing Interstitial Microwave Hyperthermia Applicators - Erb, J.; Engelbrecht, Rainer; Schaller, Gerhard; Müller, R. G.; Sauer, R. (26. Wissenschaftliche Tagung der Deutschen Gesellschaft für Medizinische Physik (DGMP) - Röntgen Centenary Congress, 1995)
UnivIS-Import:2015-04-16:Pub.1995.tech.IE.LEH.experi

Experiments Characterizing Interstitial Microwave Hyperthermia Applicators - Erb, J; Engelbrecht, Rainer; Schaller, G; Seegenschmiedt, H (1995)
lhft_intern.bib::thirty_years_LHFT_375

Experiments Charakterizing Invasive Microwave Hyperthermia Applicators - Development of a Quality Assurence and Applicator Test Program - Erb, J.; Engelbrecht, Rainer; Schaller, Gerhard; Sauer, R. (Proceedings of the 7th International Congress on Hyperthermic Oncology, 1996)
UnivIS-Import:2015-04-16:Pub.1996.tech.IE.LEH.experi

Extended Kalman filtering for joint mitigation of phase and amplitude noise in coherent QAM systems - Pakala, Lalitha; Schmauß, Bernhard (Optics Express, 2016)
We numerically investigate our proposed carrier phase and amplitude noise estimation (CPANE) algorithm using extend Kalman filter (EKF) for joint mitigation of linear and non-linear phase noise as well as amplitude noise on 4, 16 and 64 polarization multiplexed (PM) quadrature amplitude modulation (QAM) 224 Gb/s systems. The results are compared to decision directed (DD) carrier phase estimation (CPE), DD phase locked loop (PLL) and universal CPE (U-CPE) algorithms. Besides eliminating the necessity of phase unwrapping function, EKF-CPANE shows improved performance for both back-to-back (BTB) and transmission scenarios compared to the aforementioned algorithms. We further propose a weighted innovation approach (WIA) of the EKF-CPANE which gives an improvement of 0.3 dB in the Q-factor, compared to the original algorithm. © 2016 Optical Society of America
lhft_intern.bib::Pakala2016c

Extended Kalman filtering for simultaneous phase and amplitude noise mitigation in WDM systems - Pakala, Lalitha; Schmauß, Bernhard (International Conference on Transparent Optical Networks (ICTON), 2015)
The proposed carrier phase and amplitude noise estimation (CPANE) algorithm using extended Kalman filter (EKF) has been employed for joint mitigation of linear and non-linear phase noise and amplified spontaneous emission (ASE) noise in wavelength division multiplexing (WDM) systems. Numerical investigations on polarization multiplexed (PM) 16-quadrature amplitude modulation (16-QAM) 28 Gbaud/s WDM systems show that the proposed EKF technique outperforms the other considered carrier phase estimation (CPE) methods in mitigating inter and intra-channel non-linearities, laser phase noise and ASE noise.
lhft_intern.bib::Pakala2015b

Extinction ratio improvement by an advanced NOLM setup - Striegler, A; Schmauß, Bernhard (IEEE Photonics Technology Letters, 2006)
We present a nonlinear optical loop mirror (NOLM)-based setup which is optimized for regeneration of signals with a poor extinction ratio caused by, e.g., high powered ghost pulses. In a conventional NOLM, the improvement of the extinction ratio is limited by the input extinction ratio or insufficient amplitude jitter reduction. These limitations can be overcome by an additional directional phase shifter. According to numerical simulation, the extinction ratio can be improved from 6 dB up to several 10 d
lhft_intern.bib::striegler06a

Extremely temperature-resistant, polarimetric radar barcode - Pöpperl, Maximilian; Adametz, Julian; Vossiek, Martin (European Microwave Week 2017: "A Prime Year for a Prime Event", EuMW 2017 - Conference Proceedings; 47th European Microwave Conference, EuMC 2017, 2017)
Chipless radio frequency identification provides a huge potential for applications with extreme environmental conditions. The low data capacities and the printability on film or paper, prevent the use of state-of-the-art realizations in scenarios with extreme temperature. Hence, we introduce a novel chipless RFID tag that overcomes these problems. Due to a polarimetric and image base data encoding, we achieve high data capacities of more than 20 bits. Furthermore we reach an outstanding temperature robustness by avoiding conductive elements and metals. The tag is composed of clay that provides an outstanding temperature resistance and enables low production costs. The tag is suited for applications with temperatures of above 1000°C and consequently opens up new fields of applications for RFID. To show the huge potential of our tag, we describe its operating principle first. Afterwards we perform tests with different tag temperatures in a laboratory.
CRIS-Team Scopus Importer:2023-03-08
Keywords: RFID

Eye-Safe High-Capacity 1-mm GI-POF Interconnects Exploiting Discrete Multitone Modulation - Kruglov, R.; Loquai, Sven; Winkler, F.; Bunge, C. A.; Schmauß, Bernhard; Ziemann, O.; Habel, K. (Proceedings of the Optical Fiber Communication Conference (OFC), 2013)
We report high capacity 1-mm graded-index polymer optical fiber (GI-POF) shortrange interconnects employing discrete multitone (DMT) modulation technique. The bit rates of 13.09 Gb/s over 15 m and 28.19 Gb/s over 1 m were achieved at 0 dBm fiber-coupled power and BER of 10-3. The record capacity of 31.74 Gb/s over 1-m link was achieved at +2 dBm fiber-coupled power. © 2013 OS
UnivIS-Import:2015-04-16:Pub.2013.tech.IE.LEH.eyesaf

Fabrication and Applications of Polymer Planar Bragg Grating Sensors Based on Cyclic Olefin Copolymers - Kefer, Stefan; Rosenberger, Manuel; Hessler, Steffen; Girschikofsky, Maiko; Belle, Stefan; Roth, Gian-Luca; Schmauß, Bernhard; Hellmann, Ralf (2019 PHOTONICS & ELECTROMAGNETICS RESEARCH SYMPOSIUM - FALL (PIERS - FALL), 2019)
CRIS-Team WoS Importer:2020-10-09

Fabrication and characterization of planar Bragg gratings in TOPAS polymer substrates - Rosenberger, M.; Hessler, S.; Belle, S.; Schmauß, Bernhard; Hellmann, R. (Sensors and Actuators A-Physical, 2015)
We report on the fabrication of polymer planar waveguides with inscribed Bragg gratings in TOPAS employing an efficient UV based single writing step technique using excimer laser. Phase shifting Mach–Zehnder interferometry indicates an UV induced increase of the refractive index in TOPAS of 6 × 10−4 and a modification depth of about 30 μm, respectively. The planar Bragg grating structures in the cyclo-olefin copolymer are characterized by a high reflectivity of about 93% and are studied with respect to their potential in optical waveguide sensing, namely temperature and strain sensing. While the Bragg reflection shows almost no cross sensitivity against humidity, it exhibits a spectral blue shift with increasing temperature of −6.5 pm/°C after multiple thermal annealing cycles. Compressive and tensile strain measurements reveal a sensitivity of 0.70 pm/μ
lhft_intern.bib::Rosenberger2015_3

Fabrication of Bragg gratings in planar PMMA: impact of UV dosage and thermal annealing - Rosenberger, M.; Girschikofsky, M.; Schmauß, Bernhard; Hellmann, R. (Optics Express, 2016)
We report on the fabrication of planar Bragg gratings in polymer substrates and study the impact of the UV dosage and a subsequent thermal annealing on the reflectivity of the gratings and the full width at half maximum bandwidth of the reflected spectra. In addition, the influence of the grating length is investigated, showing that gratings as short as 4 mm continuously exhibit good reflection properties, facilitating miniaturized sensor designs. Moreover, we highlight that the polymer Bragg gratings exhibit a remarkable stable reflected spectrum for over two years. Finally, the experimentally determined spectral characteristics of the Bragg gratings are compared to simulated results revealing excellent agreemen
lhft_intern.bib::rosenberger2016fabrication

Fabrication of Lattice-Like Waveguides in Planar Cyclic Olefin Copolymers - Kefer, Stefan; Pape, Natalie; Schmauß, Bernhard; Hellmann, Ralf (Proceedings - 28th International Conference on Optical Fiber Sensors, OFS 2023, 2023)
This work demonstrates the femtosecond laser-based fabrication of lattice-like waveguides in planar cyclic olefin copolymers. An overview of the fabrication process is provided and waveguiding in the C-band is proven via optical near-field analysis.
CRIS-Team Scopus Importer:2024-12-16

Faser-Bragg-Gitter (FBG) in Spezialfasern mit hohen Leistungsdichten - Engelbrecht, Rainer (Bayerisches Laserzentrum, Workshop Optische Fasern - Faseroptische Kopmonenten für hohe Leistungen, 2009)
UnivIS-Import:2015-04-16:Pub.2009.tech.IE.LEH.faserb

Faser-Bragg-Gitter in Spezialfasern für Raman-Faserlaser - Siekiera, Alexander; Engelbrecht, Rainer; Welzel, Oliver; Hagen, Johannes; Schmauß, Bernhard (Frühjahrstagung der Deutschen Physikalischen Gesellschaft (DPG) (4.3 Laseranwendungen, Lasermaterialbearbeitung) ISSN 0420-0195 March,14, 2008)
UnivIS-Import:2015-04-16:Pub.2008.tech.IE.LEH.faserb