Spectrum-Oriented FFBP Algorithm in Quasi-Polar Grid for SAR Imaging on Maneuvering Platform

In this letter, a new spectrum-oriented fast factorized backprojection (FFBP) algorithm is proposed for synthetic aperture radar (SAR) imaging on a maneuvering platform. Specifically, an analytical SAR image spectrum is derived in a novel quasi-polar coordinate system based on the FFBP, which makes it easy to incorporate with an autocalibration process for both systematic and nonsystematic errors. Different from the conventional FFBP algorithms developed in polar grid, the proposed algorithm devised in quasi-polar gird conducts the motion-induced phase error as a space-invariant component, which will definitely facilitate the phase autofocusing process during the FFBP recursions. Subsequently, a phase autofocusing process is incorporated in the resultant SAR image formation algorithm. Simulations and discussions are presented to show the focusing quality improvement made by the proposed algorithm.