Complementary time domain and frequency domain echo suppression for accurate antenna field transformation in arbitrary measurement environments
Final Report Abstract
Antennas are an essential part of our everyday life. They are, e.g., required for mobile communications, aviation security, or satellite communication and navigation. The research results obtained in the performed project enable accurate measurements of the radiated fields of an antenna - even in arbitrary echoic measurement environments, which could not be handled satisfactorily before. To this end, we have identified the major echo influences of different measurement setups (moving antenna under test or moving probe antenna) on the measurement results. Existing echo suppression techniques were consequently improved and new methodologies for echo suppression were created, e.g., adaptive time-domain filtering of different equivalent current contributions. The enhancements of the algorithms allow to determine the radiation behavior of an antenna under test with high accuracy even in complicated and highly-echoic environments. Successful echo suppression depends on the ability to acquire sufficient measurement data. The measurement data must be processed with targeted methods to separate the echo influences from the measurement data and remove the separated echo contamination from the desired antenna patterns. Frequency domain methods have been combined with time domain methods to beneficially exploit complementary properties of both worlds. Furthermore, the combination of frequency- and time-domain data ensures that the resulting data of practically feasible measurement setups deliver sufficiently diverse measurement samples. As far as possible, the new echo suppression techniques have been implemented into the Fast Irregular Antenna Field Transformation Algorithm (FIAFTA) [Eib15, Kor19]. With the echo suppression incorporated into FIAFTA, data from irregularly sampled measurements in environments with arbitrarily located echo sources can be processed in a very flexible manner. As long as sufficiently many measurement data are acquired with known probe antenna positions, there are almost no limitations on the measurement setup (in particular, in contrast to conventional methods, it is not necessary to position the probe antenna accurately at predefined locations). The research results from this project open up possibilities for relevant new antenna measurement applications. In-situ measurements of fixed installed antennas outside of ideal laboratory environments are now as possible as radiation measurements in industrial production sites. The publications which are associated with this project have won several national and international awards such as the “Best Measurement Paper Award” at the European Conference on Antennas and Propagation (EuCAP) 2020, the VDE Bayern Award 2022, and the VDE ITG Dissertation Award 2022.
Publications
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Equivalent source and pattern reconstruction from oversampled measurements in highly‐reflective environments. IET Microwaves, Antennas & Propagation, 13(13), 2232–2241.
Knapp, Josef; Kornprobst, Jonas & Eibert, Thomas F.
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Near-Field Antenna Pattern Measurements in Highly Reflective Environments. IEEE Transactions on Antennas and Propagation, 67(9), 6159-6169.
Knapp, Josef & Eibert, Thomas F.
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Time-Gating the Sources in Inverse Equivalent Source Reconstruction Problems to Eliminate Mutual Coupling Effects. 2019 International Conference on Electromagnetics in Advanced Applications (ICEAA), 0312-0312. IEEE.
Knapp, Josef; Kornprobst, Jonas; Paulus, Alexander & Eibert, Thomas F.
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Propagating Plane-Wave Expansions for Microwave Near-Field Imaging and Radar Cross Section Determination, Dissertation, Technical University of Munich, May
Neitz, Ole
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Suppressing Undesired Echoes by Sparsity Based Time Gating of Reconstructed Sources. 2020 14th European Conference on Antennas and Propagation (EuCAP), 1-4. IEEE.
Knapp, Josef; Kornprobst, Jonas & Eibert, Thomas F.
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Accuracy and Conditioning of Surface-Source Based Near-Field to Far-Field Transformations. IEEE Transactions on Antennas and Propagation, 69(8), 4894-4908.
Kornprobst, Jonas; Knapp, Josef; Mauermayer, Raimund A. M.; Neitz, Ole; Paulus, Alexander & Eibert, Thomas F.
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Antenna Field Measurements and Transformations in Arbitrary Echoic Environments, Dissertation, Technical University of Munich, December
Knapp, Josef
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Spatial Distribution of Equivalent Echo Sources in Antenna Measurements with a Moving Antenna Under Test. 2022 16th European Conference on Antennas and Propagation (EuCAP), 1-5. IEEE.
Knapp, Josef & Eibert, Thomas F.
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Separating Field Contributions by their Source Volumes: Uniqueness and Limitations. 2023 17th European Conference on Antennas and Propagation (EuCAP), 1-5. IEEE.
Knapp, Josef & Eibert, Thomas F.
