Nonuniform sampling PFA for squint spotlight SAR imaging

This paper improved polar format algorithm (PFA) based on nonuniform azimuth sampling for squint spotlight synthetic aperture radar (SAR) imaging. The range resampling for chirped signal is carried out by chirp z transform (CZT). The novel nonuniform azimuth sampling during the echo data collection enables the utilizing of CZT in azimuth resampling. According to the data collection geometry, the precise expression of phase error induced by wavefront curvature is deduced, and then the overlapped subaperture approach (OSA) is adopted to correct the geometric distortion and defocus arising from the effect of wavefront curvature. Simulation results confirm the validity of the presented approach.