Impact of Subarray Position Errors in mm-Wave MIMO Automotive Radar Polarimetric Phase Calibration

The impact of subarray position errors on polarimetric phase calibration in mm-wave MIMO automotive radar systems is studied for the first time.A 45 linearly polarized 77 GHz radar with an asymmetric MIMO topology is employed for demonstration purpose.The study reveals that minor subarray position deviations, about 0.03 on average among the virtual array elements, can significantly influence the calibrated polarimetric phase response when the target is located off-broadside.Experimental results show that accounting for realized subarray positions reduces the cross-polarized phase difference's standard deviation by about 54%.For co-polarized targets at 30 azimuth and 60 azimuth, the mean phase difference decreases by 90% on average.These findings highlight the critical importance of using accurate subarray position information for processing and achieving reliable polarimetric calibration.