Simulation Based Uncertainty Analysis for Active Two-Way-Radiation Pattern Measurements of Circularly Polarized Antennas

Traditional antenna measurement systems are often ineffective in the case of integrated systems like modern automotive radar systems due to the lack of accessibility to the antenna's feed point. To address this issue, a frequency-modulated continuous wave (FMCW) radar system's two-way radiation pattern can be measured by utilizing the radar's own transmit and receive modules while measuring against a reflector. However, it is important to note that this method introduces measurement uncertainties distinct from those encountered in conventional antenna measurements. In this study, we delve into the uncertainties caused by mechanical misalignments through simulations to shed light on their impact and characteristics for circularly polarized antennas, taking into account the polarization-dependent even and odd reflections of plate, dihedral and trihedral reflectors. Although discrepancies between the theoretically calculated two-way radiation pattern and the simulations can be found, the method can be validated in general and proves robustness against misalignment errors of the reflectors and antenna under test (AUT).