Eliminating Range Migration Error in mm-Wave Radars for Angle of Arrival Estimation

Abstract

Millimeter-wave (mm-Wave) radars are used to determine an object’s position relative to the radar, based on parameters such as range (R), azimuth angle ( $\theta $ ), and elevation angle ( $\phi $ ). Radars typically operate by transmitting a chirp signal, receiving the reflected signal from objects in the environment, and combining these signals at the receiver (RX). In systems with multiple antennas, the range is calculated for each transmitter (TX)–RX pair, producing multiple measurements that are averaged to improve accuracy. Angle estimation, however, relies on analyzing phase differences between antenna paths, and since it involves a single calculation across all antenna components, it does not benefit from averaging. In addition to random errors, systematic errors also affect the angle estimation. Specifically, the object’s distance varies slightly across the virtual antennas (formed by TX-RX combinations), causing shifts in the peak position of range estimation. This phenomenon, known as range migration, introduces errors. This article examines the root causes of range migration and its impact on angle of arrival (AoA) estimation, proposing effective solutions to mitigate these effects and enhance the overall accuracy of angle estimation.