Fast time domain approach for bistatic forward-looking sar imaging based on subaperture processing and local beamforming

A fast time-domain approach called fast factorized backprojection (FFBP) algorithm based on the subaperture processing and local beamforming is presented for the bistatic forward-looking SAR (BFSAR) imaging. It not only precisely handles spatial-variance, serious range-azimuth coupling and complicated motion errors, but also greatly improves imaging efficiency compared with the backprojection (BP) algorithm. Besides, it requires the local beamforming from radar echoes as an intermediate stage in the slant-range plane instead of ground plane, which is accurately referenced to transmitter and receiver tracks. Finally, it analyzes the bistatic range error considering the motion errors to derive the requirements of selecting the size of subapertures and subimages. Experimental results show the validity of the proposed FFBP algorithm.