A Novel Unambiguous Spectrum Reconstruction Algorithm for Space-borne High Resolution and Wide Swath SAR Imaging Based on Iterative Adaptive Algorithm

Due to the constraint of the minimum antenna restriction, there is an irreconcilable contradiction between high resolution and wide swath (HRWS) in a single-channel spaceborne synthetic aperture radar (SAR) system. To address this contradiction, the use of azimuth multichannel system can effectively realize the HRWS SAR imaging by taking the beam forming techniques. In this paper, a novel unambiguous spectrum reconstruction algorithm for space-borne multichannel HRWS SAR imaging is proposed. The proposed method firstly compensates the linear phase structure related to the along-track baseline in the Doppler domain. Then, the covariance matrix is reconstructed along azimuth direction based on adaptive iterative algorithm (IAA). Hence, based on the estimated covariance matrix, an unambiguous signal spectrum can be accurately restored according to the linearly constrained minimum variance (LCMV) criterion. Finally, a well-focused HRWS SAR image can be obtained by applying the typical SAR image algorithm. The major advantage of the proposed method is that it can realize the azimuth ambiguity elimination in a non-homogeneous scene. Both simulated and real data processing results are used to validate the effectiveness of the proposed method.