Distortion Correction and Scene Size Limits for SAR Bistatic Polar Format Algorithm

The polar format algorithm (PFA) efficiently implements the computationally complex synthetic aperture radar (SAR) matched filter (MF) using a first-order Taylor series approximation of the differential range in the MF kernel. Using the approximation causes spatially varying distortion and defocus effects in the SAR image. These limitations have motivated research into developing distortion and defocus correction algorithms. Alternatively, the distortion and defocus effects may be mitigated by limiting the size of the image. While several solutions to these problems have been published for monostatic PFA, significantly less work has been published in the area of bistatic PFA, which offers operational advantages and geometric flexibility over the monostatic case. In this paper, a temporal Taylor series expansion based analysis of the MF phase and PFA phase is used to derive both a distortion correction algorithm, and scene size limitation for a SAR image produced using bistatic PFA.