Radar scheme with raised reflector for NLOS vehicle detection. - In: IEEE transactions on intelligent transportation systems, Bd. 23 (2022), 7, S. 9037-9045
The employment of passive reflectors enables the millimeter-wave automotive radars to detect an approaching vehicle in non-line-of-sight conditions. In this paper, the installation of such reflectors above the sidewalk at an intersection is proposed and studied, avoiding pedestrians' blockage and road dust effect at ground level. Through the analysis of the backscattering power, it is shown that the suggested scheme may detect an approaching vehicle in the blind zone at distances of 30,łdots,50 m to the intersection point. Additionally, the analysis shows that efficient operation is highly dependent on the spatial orientation and size of the reflector. Even a few degrees rotation may change the detecting range by several meters. In turn, the larger area of the reflector may cover longer detecting distances, improving the radar scheme's overall performance. It is also shown that further performance enhancement can be achieved by employing a C-type radar, contributing an extra 5 dB to the backscattering power relative to an A-type radar. However, despite these improvements, the strongest scattering centre of the detectable vehicle is systematically identified to the bumper zone.
https://doi.org/10.1109/TITS.2021.3090313
Evaluation of integral quantities of over the air automotive antenna measurements. - In: 2021 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting, (2021), S. 1954-1955
This document outlines the Over the Air (OTA) testing methodology which is currently employed for full automotive antennas and provides a pertinent Figure of Merit.
https://doi.org/10.1109/APS/URSI47566.2021.9704228
Plastic-embedded patch antenna array for automotive satellite communication in the Ka-band. - In: 2021 1st International Conference on Microwave, Antennas & Circuits (ICMAC), (2021), S. 1-4
https://doi.org/10.1109/ICMAC54080.2021.9678254
Systemvalidierung von Fahrzeugradaren mittels drahtloser Techniken - SafeMove : Schlussbericht der TU Ilmenau zum F&E-Verbundvorhaben : Laufzeit des Vorhabens: 01.01.2017-30.09.2020. - [Ilmenau] : [Technische Universität Ilmenau, Thüringer Innovationszentrum Mobilität]. - 1 Online-Ressource (36 Seiten, 5,73 MB)Förderkennzeichen BMBF 16ES0547K
https://doi.org/10.2314/KXP:178728459X
Bi-static reflectivity measurements of microwave absorbers between 2 and 18 GHz. - In: 2021 Antenna Measurement Techniques Association Symposium (AMTA), (2021), insges. 6 S.
In anechoic chambers, the level of spurious reflections is determined by the reflectivity of the installed absorbers and is usually estimated using ray-tracing methods. But since the basic assumption of a purely specular reflection in most of these ray-tracing methods can lead to insufficient results, the reflectivity of the absorbers must be analyzed for oblique incidence and over a broad range of observation angles. In this paper, a bi-static measurement setup is proposed, which overcomes angular limits of the NRL-arch method and allows to analyze the scattering behavior of absorbers in an extended angular range. Using this setup, and applying the radar cross-section method, the reflectivity of two types of pyramidal absorbers was analyzed with respect to different illumination and observation angles for parallel and perpendicular polarization between 2 and 18 GHz. While the measurement results for normal incidence agree well with the specifications, additional non-specular reflections of similar strength were detected in the time-domain at different observation angles. Especially for the case of oblique wave incidence, it becomes apparent that the highest reflectivity does not necessarily occur for specular reflection. These findings help to improve the understanding of the scattering behavior of absorbers in general, as more comprehensive analyses become possible with this method.
https://doi.org/10.23919/AMTA52830.2021.9620601
Simulation and measurement of locomotive antennas in the installed state based on a scaled mockup. - In: 2021 Antenna Measurement Techniques Association Symposium (AMTA), (2021), insges. 6 S.
Accurate characterization of locomotive antennas is key to safe and robust railway signaling and control communication. With the introduction of new technologies and the foreseeable migration from the GSM-R standard towards FRM CS, new wireless applications and specifications arise, and suitable antenna solutions need to be developed and tested. Moreover, the rooftops of modern locomotives present a dense and harsh environment; therefore, potential antenna mounting spaces should be carefully evaluated to avoid undesirable degradations of the antenna radiation patterns. Due to the electrically large and complex structure of locomotives, full-scale testing is challenging to perform, especially under laboratory conditions. Antenna measurements with geometrically scaled models present a powerful alternative to address this issue. In this paper, we present and discuss antenna measurement results of a scaled locomotive mockup. The mockup incorporates two different cabin geometries, one with a step-like rooftop contour, and one with a smooth slightly tilted geometry. First, the optimum scaling factor was identified and validated through numerical simulations. Afterwards, antenna measurements with a scaled locomotive mockup were carried out in our automotive antenna measurement facility VISTA. The measured results were compared with the numerical simulations, where a good correlation above 80 % was found. Secondly, the impact of the rooftop geometries, and superstructures on the roof has been investigated for a range of operational frequencies between 700 and 2600 MHz. The results reveal that the parasitic impact of the antenna environment becomes more pronounced at higher frequencies.
https://doi.org/10.23919/AMTA52830.2021.9620626
Precise phase center localization of automotive LTE antennas in the installed state through phaseless LTE uplink measurements. - In: 2021 Antenna Measurement Techniques Association Symposium (AMTA), (2021), insges. 5 S.
With the event of integrated and multi-standard wireless links, phaseless antenna measurements are attracting more and more interest in research. Especially in the context of connected and automated driving, antennas, frontends, and digital signal processing units merge into telematic units and require new methods for performance evaluation in the installed state. The measurement of the phase diagram and the exact absolute positioning of electrically large antennas, i.e., antennas interacting with the car body, present challenges for safety-relevant applications and reliable test methods. This paper describes a way to determine the position of automotive antennas in the installed state with sub-wavelength precision from phaseless measurements. Realistic L TE uplink signals were used as test signals as they would be transmitted by an active device in a real-world scenario. The localization algorithm is based on orthogonal power measurements of the transmitted signal on a cylinder surface and a non-linear optimization. By comparison with a conventional localization based on spherical far-field data, an accuracy of the approach of less than 1 cm was achieved, which is less than N16 at the considered frequency of 1870 MHz.
https://doi.org/10.23919/AMTA52830.2021.9620655
Bi-static RCS variations of pedal and wheel movements on bicycles between 1 and 10 GHz. - In: 2021 Antenna Measurement Techniques Association Symposium (AMTA), (2021), insges. 6 S.
One benefit of cooperative automated and connected driving lies in the fusion of multiple mobile wireless sensor and data transmission nodes, covering complementary technologies like radar, cellular and ad-hoc communications, and alike. Current developments indicate enormous potential to increase the environmental awareness through joint communication and radar sensing. In this respect, future channel models require knowledge of bi-static reflectivities of road users over a range of illumination and observation angles, both in the nearfield and in the far-field. To establish reference data and model such angle-dependent RCS variations, this paper deals with realistic pedal and wheel rotations of a bicycle based on electromagnetic simulations. In the simulation setup, idealized far-field conditions with plane-wave illumination and observation were assumed, while the angles covered the entire azimuth with 201 variations of the pedal and wheel positions. The fluctuation of the RCS is analyzed and discussed in terms of its probability density and cumulative distribution functions. Depending on the angular constellation, the range of the fluctuation varied between 1 dB and 14 dB, while the specular reflection and forward-scattering showed almost no fluctuation.
https://doi.org/10.23919/AMTA52830.2021.9620542
Evaluation of automotive antenna over the air performance. - In: 2021 International Symposium on Antennas and Propagation (ISAP), (2021), insges. 2 S.
This document outlines the measurement methodology currently employed to evaluate wireless technology on vehicles. Near Field Over the Air measurement results are provided and the Figure of Merit developed to assess the performance is reviewed. Simulation results of a more complex measurement scenario are also presented.
https://doi.org/10.23919/ISAP47258.2021.9614413
Agile multi-beam front-end for 5G mm-wave measurements. - In: International journal of microwave and wireless technologies, ISSN 1759-0795, Bd. 13 (2021), 7, S. 740-750
The 5th generation new radio (5G NR) standards create both enormous challenges and potential to address the spatio-spectral-temporal agility of wireless transmission. In the framework of a research unit at TU Ilmenau, various concepts were studied, including both approaches toward integrated circuits and distributed receiver front-ends (FEs). We report here on the latter approach, aiming at the proof-of-principle of the constituting FEs suitable for later modular extension. A millimeter-wave agile multi-beam FE with an integrated 4 by 1 antenna array for 5G wireless communications was designed, manufactured, and verified by measurements. The polarization is continuously electronically adjustable and the directions of signal reception are steerable by setting digital phase shifters. On purpose, these functions were realized by analog circuits, and digital signal processing was not applied. The agile polarization is created inside the analog, real-time capable FE in a novel manner and any external circuitry is omitted. The microstrip patch antenna array integrated into this module necessitated elaborate measurements within the scope of FE characterization, as the analog circuit and antenna form a single entity and cannot be assessed separately. Link measurements with broadband signals were successfully performed and analyzed in detail to determine the error vector magnitude contributions of the FE.
https://doi.org/10.1017/S1759078721000842