Wavefront Curvature Correction for Missile Borne Spotlight SAR Polar Format Image

The polar format algorithm (PFA) for spotlight synthetic aperture radar (SAR) is influenced by wavefront curvature error. The previous wavefront curvature compensation methods are all assumed that the height of the radar is constant, these compensation methods cannot be directly applied to the case of missile borne SAR where the platform always has large dive angle. In this paper, the precise expression of wavefront curvature phase error in the frequency domain of missile borne SAR is derived. Image domain post-processing steps, including space-variant filtering and geometric distortion correction, are employed to compensate the quadratic and linear phase error terms. This method further improves the precision of wavefront curvature compensation. Simulation results validate the theoretical analysis.