Polar format algorithm based on fast Gaussian grid non‐uniform fast Fourier transform for spotlight synthetic aperture radar imaging

Abstract

Conventional polar format algorithm (PFA) and its variations normally assume an ideal imaging geometry of a linear flight path, which cannot counteract the non-uniformity of samples existing in the circumstance of a highly non-linear aperture. This scenario may occur because of various factors such as rugged topography, atmospheric turbulence and intended manoeuvres. To address this challenge, this study develops a novel PFA with aperture accommodation for spotlight synthetic aperture radar (SAR) imaging. The proposed algorithm provides a new adaption of the fast Gaussian grid (FGG) non-uniform fast Fourier transform (NUFFT) scheme to two-dimensional (2D) SAR imaging of 3D scene, whose main idea is to convolve the non-uniform samples onto a uniform grid with a Gaussian kernel and then exploit the efficient 2D FFT for image reconstruction. In virtue of the 2D FGG NUFFT, a favourable tradeoff between reconstruction precision and computational efficiency is gained. Simulations illustrate the superiority of the proposed algorithm over the conventional non-uniform Sinc interpolation method. Also, the public real Gotcha dataset validates the effectiveness of the authors method.