A CZT-based continuous varying PRF polar format algorithm for highly squinted spotlight SAR

The polar format algorithm (PFA) is a classic algorithm for processing spotlight synthetic aperture radar (SAR) data and is extensively used in practical applications nowadays, mainly because its well performance in processing highly squinted data. Based on the chirp Z-Transform (CZT), PFA can be implemented accurately without any interpolation in the broadside case; however, for the squint mode case, since the input data are not uniformly distributed with same sampling intervals, the CZT algorithm requests interpolation in the azimuth dimension to obtain the uniform sample spacing, which leads to phase and amplitude error. To improve the processing accuracy under the squint mode, a CZT-based continuous varying PRF PFA is introduced. It achieves uniformly scaled grid along azimuth direction in wavenumber domain; as a result, interpolation in both range and azimuth dimensions can be avoided.