Target Elevation Estimation for Passive Radar Based on Double-Layer Uniform Circular Array

This article investigates the target elevation estimation problem for passive radar based on a double-layer uniform circular array (DUCA). First, we propose a calibration method for the DUCA. The array errors considered in the calibration include amplitude errors, phase errors, and coupling errors. Then, we study the problem of elevation estimation when the target echo contains the ground multipath. The ground multipath will degrade the performance of the elevation estimation algorithm. We analyze the influence of the ground multipath on elevation estimation by establishing a multipath geometric model. The radar receiving antenna height, ground reflection coefficient, ground tilt angle, and other parameters are considered in this model. An iterative improved generalized multiple signal classification (IIG-MUSIC) algorithm for passive radar is proposed. We analyze the estimation performance of the proposed algorithm by calculating the elevation Cramér–Rao bound (CRB) of a DUCA under a multipath model. Simulation and real radar data show that the proposed algorithm can effectively improve the elevation estimation performance and positioning accuracy of passive radar.