Post-Processing for Installed-Performance Testing of Automotive Antennas for Satellite Communications

Advanced post-processing of automotive antenna measurement data is essential, particularly when antennas are installed in locations such as rear spoilers, offset from the phase center of the measurement facility. Conventional nearfield-to-far-field transformations, such as the spherical-wave expansion, assume the antenna phase center is located within the minimum measurement sphere. However, as operational frequencies in-crease, the minimum sphere shrinks for test facilities with fixed angular resolution. If the antenna is located outside this region, transformation errors occur, leading to inaccurate radiation patterns and total radiated power estimates. To mitigate these effects, we applied the translated spherical-wave expansion (TSWE) method, which compensates for phase-center offsets relative to the origin of the measurement sphere, improving the accuracy of installed-performance testing. A dedicated practical case study comparing measurements in different antenna test facilities, including our latest Gantry arm-based extension of the virtual road – simulation and test area (VISTA) at TU Ilmenau, highlights the effectiveness of this approach, particularly for embedded automotive antennas that were designed for non-ter-restrial links at 5.9 GHz. The results show a significant reduction of errors, closely aligning with reference measurements.