A Hybrid Multichannel Processing Method for Spaceborne Hybrid Phased-MIMO SAR with Application to Multi-Direction Swath Imaging

This paper proposes a hybrid multichannel processing method for spaceborne Hybrid Phased-MIMO SAR (HPMSAR) that can achieve different applications of multi-direction swath imaging on the same platform. The method is optimal because it is a combination of two-dimension (2D) advanced digital beamforming (DBF) technology and multichannel pre-filter technology for highresolution wide-swath SAR signal processing. Multichannel signal processing technology for future spaceborne SAR will no longer be single and this combination may be the best choice. The proposed method could avoid spectrum aliasing caused by low pulse repetition frequency (PRF), separate the overlapped echoes caused by different subpulses corresponding to multi-direction swathes and remove the range ambiguity and azimuth ambiguity deeply. At first, we build the signal model of HPMSAR system. Furthermore, the pre-filter design is presented by using matrix inversion method. Then, we address different methods applied to 2-D DBF and propose the advanced linearly constrained minimum variance (LCMV) method. Image results on simulated distributed targets validate the proposed hybrid multichannel processing method.