A fast circular convolution algorithm based on NUFFT for near-field SAR imaging

A fast cyclical convolution algorithm based on the two dimensional (2-D) nonuniform fast Fourier transformation (NUFFT) is presented in this paper. This method combines the azimuth convolution with min-max Nonuniform Fast Fourier Transform (min-max NUFFT) approach which has been shown to provide considerably improved image quality relative to the traditional interpolation algorithm. Through numerical simulations and experimental results, we show that the proposed algorithm can provide images with lower sidelobes but requires more computational time than that of the cyclical convolution method based on the linear interpolation and FFT. The algorithm presented in this paper is also suitable for the bistatic antenna array.