Sum and difference beamforming for angle-doppler estimation with STAP-based radars

The angle and Doppler estimation performance of the traditional space-time adaptive processing (STAP) method usually degrades in terms of estimation accuracy, especially for slowly moving targets. In this paper, a novel sum and difference beamforming approach with STAP-based radar is proposed, where multiple constraints, including the magnitude and phase constraints, derivative constraints, and zero-point constraints, are incorporated. Since the derivative constraints are independent of the array geometry, the proposed sum and difference beamforming method is applicable for both symmetric and asymmetric arrays. Also, the coupling relationship between angle and Doppler estimates is resolved by properly modifying the zero-point constraints. Moreover, the proposed method is robust against the coherent jamming contamination. Numerical examples indicate that the proposed method offers a significant performance improvement in angle and Doppler parameters estimation.