DOA Estimation Using Multipath Echo Power for MIMO Radar in Low-Grazing Angle

In this paper, we propose a novel direction of arrival estimation algorithm for multi-input multi-output radar in a low-grazing angle (LGA) condition. Considering the effect of earth curvature and atmosphere, we derive the received signal model based on the assumption that the waveforms are transmitted by widely spaced sensors and received by some separated uniform linear arrays (ULAs). In order to use the multipath echo power, the proposed algorithm can select the best transmitter multipath reflected coefficients by optimizing the virtual transmitter signal, remove the coherency by improved spatial smoothing method and select the best receiver multipath reflected coefficients by peaks searching method. As a result, the algorithm can avoid the attenuation caused by different multipath reflected coefficients and targets glint, resulting from the spatial diversity for transmitter sensors and receiver subarrays. Simulation results show that, in LGA, the proposed algorithm can achieve performance improvements for the realistic LGA model, and also with the increase of the transmit sensors and ULAs or compared with other recently developed methods.