Enhanced Polarimetric Phase Calibration for Automotive Radar Using Near-Field Dihedral Scattering With Misalignment Angle Correction

Abstract

Calibration of mm-Wave fully-polarimetric MIMO radar is considered. An enhanced polarimetric phase calibration method is proposed, which operates in the far-field region of the radar but utilizes calibration targets within their nearfield scattering region. The method exploits near-field dihedral scattering with yaw angle correction to improve calibration repeatability across different measurement sessions. Simulations and measurements show that using a larger dihedral compared to the smaller one employed for far-field calibration in the near-field region increases received power by up to 15.7 dB, thereby enhancing the signal-to-noise ratio. Although near-field sensitivity to alignment introduces phase variations, the proposed yaw angle correction effectively compensates them, achieving phase consistency comparable to far-field calibration under high-SNR conditions, and outperforming it under low-SNR conditions. The method provides a robust approach for stable polarimetric calibration in compact automotive radar setups.