@inproceedings{EberspaecherEibertRusser, author = {Ebersp{\"a}cher, Mark A. and Eibert, Thomas F. and Russer, Peter}, title = {An Analysis Procedure for 3D Metamaterial Unit Cells Based on the Rotated Transmission-Line Matrix Scheme}, series = {Loughborough Antennas and Propagation Conference, Loughborough, Großbritannien}, booktitle = {Loughborough Antennas and Propagation Conference, Loughborough, Großbritannien}, publisher = {IEEE}, doi = {10.1109/LAPC.2010.5666239}, pages = {161 -- 164}, abstract = {A procedure is presented which enables, based on electromagnetic simulation, simple network parameter determination of three dimensional Composite Right/Left-Handed (CRLH) unit cells. The procedure is successfully applied to a three dimensional structure derived from the rotated transmission-line matrix (TLM) scheme. Based on the calculated element values a CRLH unit cell is optimized in order to realize a well balanced metamaterial structure.}, language = {en} } @inproceedings{TolaniEberspaecherEibert, author = {Tolani, Harshita and Ebersp{\"a}cher, Mark A. and Eibert, Thomas F.}, title = {Composite Right/Left-Handed Leaky Wave Antenna with Structurally Non-Periodic Unit Cell Arrangement}, series = {Loughborough Antennas and Propagation Conference, Loughborough, Großbritannien}, booktitle = {Loughborough Antennas and Propagation Conference, Loughborough, Großbritannien}, publisher = {IEEE}, doi = {10.1109/LAPC.2010.5666240}, pages = {165 -- 168}, abstract = {A unique dominant mode structurally non-periodic Composite Right/Left-Handed (CRLH) Transmission-Line (TL) based Leaky Wave Antenna (LWA) is proposed, with a novel kind of unit cell arrangement, which utilizes the additional degree of freedom obtained from non uniform spacing between the unit cells to control the radiation behavior of the antenna. We investigated the influence of non uniformly spaced unit cell arrangements on the radiation performance of the CRLH LWA and determined an optimum unit cell arrangement which leads to an improvement of 3 dB in side lobe level (SLL) suppression when compared to its structurally periodic counterpart for broadside direction. Furthermore, various aspects which are critical and should be taken into consideration while designing a structurally non-periodic LWA comprising of non uniformly spaced unit cell arrangement are also addressed.}, language = {en} } @inproceedings{EberspaecherEcclestonEibert, author = {Ebersp{\"a}cher, Mark A. and Eccleston, Kim and Eibert, Thomas F.}, title = {Realization of Via-free Microstrip Composite Right/Left-Handed Transmission Lines}, series = {Proceedings of the German Microwave Conference, M{\"u}nchen, Deutschland}, booktitle = {Proceedings of the German Microwave Conference, M{\"u}nchen, Deutschland}, publisher = {IEEE}, doi = {10.1109/GEMIC.2009.4815867}, pages = {1 -- 4}, abstract = {Three via-free microstrip composite right/left handed (CRLH) unit cells are presented, which enable easy and low-cost fabrication of transmission lines exhibiting the infinite wave length phenomenon. All guiding structures are designed in an entirely printed circuit technology based on the transmission line theory and its equivalent circuit. Supported by EM simulation software the unit cells are optimized to operate at a frequency of 10 GHz. Appropriate experiment boards were fabricated and the measurements obtained from a microwave vector network analyzer are compared to the simulated results. Furthermore, an approach is worked out to determine the dispersion characteristics of the unit cells without the need of an equivalent circuit. The introduced and applied method allows to calculate dispersion relations directly based on simulated and measured ABCD parameters. Left and right-handed regions are pointed out by the dispersion diagram and the so-called infinite wavelength phenomenon is exhibited.}, language = {en} } @inproceedings{LiebgottJandtEberspaecheretal., author = {Liebgott, Florian and Jandt, Marvin and Ebersp{\"a}cher, Mark A. and Liebgott, Annika and Yang, Bin}, title = {Spectrum-based online estimation of IQ imbalance for near field radar distance sensors}, series = {29th European Signal Processing Conference (EUSIPCO), Dublin, Irland}, booktitle = {29th European Signal Processing Conference (EUSIPCO), Dublin, Irland}, doi = {10.23919/EUSIPCO54536.2021.9616359}, abstract = {A mismatch of the in-phase (I) and quadrature (Q) signal path of a direct-conversion receiver results in IQ imbalance, which distorts the demodulated signal. However, if the imbalance parameters can be estimated, the influence of the IQ imbalance can be compensated. We propose a novel method to estimate the parameters during normal operation of a stepped frequency continuous wave (SFCW) radar distance sensor without the need for a pilot signal. To estimate the imbalance parameters, we exploit the structure of the spectrum of the demodulated signal. Evaluating our method on real sensor data shows superior results especially for very short distances.}, language = {en} } @inproceedings{JandtEberspaecherKallfass, author = {Jandt, Marvin and Ebersp{\"a}cher, Mark A. and Kallfass, Ingmar}, title = {Radar imaging based on multiple non-coherent antennas}, series = {Proceedings of the SPIE, Florida, USA}, booktitle = {Proceedings of the SPIE, Florida, USA}, doi = {10.1117/12.2585568}, abstract = {A concept for radar imaging based on multiple incoherent millimeter wave antennas is presented. The goal is to use 3D-Imaging, where the object moves along a line and passes a linear array of antennas. To reduce the hardware complexity, a novel radar principle is introduced, which does not require a coupling between TX and RX, but a reference reflector. The RX performs just a RF-power measurement for each frequency step in a SFCW setup. After preprocessing the raw data, any focusing algorithm can be used to obtain the 2D image. Multiple 2D images can be combined to 3D with backprojection.}, language = {en} } @inproceedings{EberspaecherDorneich, author = {Ebersp{\"a}cher, Mark A. and Dorneich, Albert D.}, title = {Level probing in highly overmoded waveguides}, series = {Proceedings of the German Microwave Conference, Cottbus, Deutschland}, booktitle = {Proceedings of the German Microwave Conference, Cottbus, Deutschland}, publisher = {IEEE}, abstract = {This paper deals with a tank level probing scenario using electromagnetic waves where the vessel supports a significant number of higher order modes which deteriorate the accuracy of the measurement. A signal model is presented which allows to estimate the accuracy of interferometric measurements taking higher order modes into account. Based on the predicted estimation an appropriate waveguide taper with a high suppression of parasitic modes is designed, fabricated and measured. The presented design approach is validated by measurements.}, language = {en} } @inproceedings{OladapoAdrianEberspaecher, author = {Oladapo, Jeleel Alao and Adrian, Simon B. and Ebersp{\"a}cher, Mark A.}, title = {Frequency-Dependent RCS Characterization of a CRLH-Based Leaky Wave Antenna}, series = {2024 Kleinheubach Conference}, booktitle = {2024 Kleinheubach Conference}, publisher = {IEEE}, doi = {10.23919/IEEECONF64570.2024.10739083}, pages = {1 -- 4}, language = {en} } @article{OladapoAdrianEberspaecher, author = {Oladapo, Jeleel Alao and Adrian, Simon B. and Ebersp{\"a}cher, Mark A.}, title = {Backscattering-Based Radiation Mode Analysis for Angle Estimation of a CRLH Leaky Wave Antenna}, series = {Advances in Radio Science}, volume = {25}, journal = {Advances in Radio Science}, publisher = {Copernicus GmbH}, issn = {1684-9973}, doi = {https://doi.org/10.5194/ars-23-59-2025}, pages = {59 -- 69}, abstract = {Abstract. This study explores the extraction of the radiation mode field from backscattering field components of a composite right/left-handed (CRLH) leaky wave antenna (LWA) to estimate the relative angle to the radiation mode field within its frequency band of operation. Two methods, transmission line delay (TLD) and impedance loading (IL), for extracting the radiation mode from backscattering field components, are employed to isolate the radiation mode field of a CRLH LWA. In the IL method, backscattered fields are measured by terminating the CRLH LWA with short and open load impedances to express the radiation mode and structure mode field components. The TLD method uses a coaxial transmission line to connect the CRLH LWA to a high-gain X-band horn antenna, enabling isolation of the radiation mode field component from the backscattered field components, using time gating. This analysis employs two measurement setups for TLD, one in which both the CRLH LWA and the horn antenna rotate along the azimuth and the other in which only the CRLH LWA rotates. The analysis shows the frequency-angle relationship of the CRLH LWA radiation mode field, which reveals the frequency-dependent features of the CRLH LWA. Additionally, an evaluation of frequency ambiguity is done to provide more insights into the effectiveness of each approach for angle estimation of CRLH LWA relative to the incident wave.}, language = {en} } @inproceedings{OladapoAdrianDaunetal., author = {Oladapo, Jeleel Alao and Adrian, Simon B. and Daun, Marian and Ebersp{\"a}cher, Mark A.}, title = {Simulation-Based Frequency-Dependent RCS Estimation of a CRLH Leaky-Wave Antenna Using Gain and Impedance-Loading Methods}, series = {2025 9th International Conference on Computational System and Information Technology for Sustainable Solutions (CSITSS)}, booktitle = {2025 9th International Conference on Computational System and Information Technology for Sustainable Solutions (CSITSS)}, publisher = {IEEE}, doi = {10.1109/CSITSS67709.2025.11295030}, pages = {1 -- 6}, language = {en} } @inproceedings{OladapoAdrianEberspaecher, author = {Oladapo, Jeleel Alao and Adrian, Simon B. and Ebersp{\"a}cher, Mark A.}, title = {Frequency-Dependent RCS Characterization of a CRLH Leaky-Wave Antenna Using Characteristic Mode Analysis}, series = {2025 Kleinheubach Conference}, booktitle = {2025 Kleinheubach Conference}, publisher = {IEEE}, doi = {10.23919/IEEECONF67516.2025.11225296}, pages = {1 -- 4}, language = {en} } @inproceedings{HolderEberspaecher, author = {Holder, Marvin and Ebersp{\"a}cher, Mark A.}, title = {A versatile method to design an equidistant MIMO array}, series = {2022 Kleinheubacher Conference, Miltenberg, Deutschland}, booktitle = {2022 Kleinheubacher Conference, Miltenberg, Deutschland}, abstract = {A design method to synthesize a uniformly weighted and equidistant multiple input multiple output (MIMO) array is proposed and explained. The method can be used to design 1D or 2D arrays without software tools or programming effort. The method is based on sequentially copying and displacing antenna groups with the help of a number scheme. A nomenclature is proposed to classify the degrees of freedom in the design procedure}, language = {en} }