A Modified Fast Factorized Back-Projection Algorithm for Squint UWB-SAR Imaging

In this paper, we investigate the mechanism of Fast Factorized Back-projection (FFBP) algorithm by revealing the relationship between the echoed signal and the spectrum of synthetic aperture radar (SAR) image projected on different coordinate systems. Based on the spectral analysis, a modified FFBP algorithm for squint ultra-wide bandwidth (UWB) SAR imaging is presented. Comparing with the conventional FFBP algorithm, the sub-aperture images are recursively mapped on pseudo polar coordinate rather than original polar coordinate. With the pseudo polar coordinate, the spectrum of sub-aperture SAR image is compacted in a narrower range. Thus only a low Nyquist sample rate is applied to the BP maps which dramatically reduces the redundant back-projections in operation. Simulation results are presented to validate the effectiveness of the proposed method in squint UWB-SAR case.