Study On Nonhomogenous Clutter Suppression For Airborne Array Radar

Space-time adaptive processing (STAP) can efficiently suppress ground clutter and strong interference, improve the ground moving target detection (GMTD) performance, and much attention has been paid on it. The STAP performance is mainly dependent on the estimation accuracy of the clutter plus interference covariance matrix. However, the range-dependence (RD) problem exists in non-side looking airborne radar (non-SLAR) system and bistatic airborne radar system, and it leads to the estimation error of the clutter plus interference covariance matrix, and then declines the STAP performance. The main content of this paper is how to depress the RD problem of the ground clutter distribution in non-SLAR system and bistatic airborne radar system and improve the STAP performance on the ground clutter and interference rejection. The detail reseach content is arranged as following:1. The clutter model of non-SLAR system and bistatic airborne radar system is built; the clutter space-time distribution of airborne radar system is also analyzed, and the RD problem of the clutter space-time distribution makes an impact on the STAP performance is studied in non-SLAR system and long baseline bistatic airborne radar system.2. Aiming at the space-time interpolation method requiring large computation quantity, the space-time separated interpretation method is proposed when range-ambiguty does not exist and little performance loss is permitted. The proposed method separately implements the interpolation transform in spatial domain and Doppler domain and it sharply reduces the computation quantity.The moving target space-time constraint RBC method is proposed. The proposed method adds the space-time constraint of the moving target in the RBC method, and it makes the proposed method compensate the RD problem in the cell under test (CUT) while keeping the moving target information which exists in the CUT.3. To solve the RD problem in airborne radar system when the range ambiguity exists, the RBC based range ambiguity clutter compensation method is proposed. The proposed method implements the long slant range clutter constraint, and it makes the proposed method compensates the RD problem of the short slant range clutter while keeping the space-time distribution of the long slant range clutter unchanged. The proposed method can acquire good performance when the antenna element error exists in the received clutter data in airborne radar system. 4. Aiming at the antenna element error causes that the space-time interpolation method can not efficiently compensate the RD problem. Two antenna element error robust space-time interpolation methods are proposed to solve this problem. The first proposed method adds the correcting steering around the clutter steering vector, and it makes the new constructed clutter space-time steering vector matrix, is robust for the antenna element error; Secondly, referring to the robust beamforming method, which adds the derivation constraint of the beam direction to make the beamforming robust for the direction error, we acquire the derivation of the azimuth angle and elevation angle, and then use the acquired derivation constraint space-time steering vectors to constraint the space-time steering vector of the clutter. To do this, the space-time interpolation is robust for the antenna element error.