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 nonuniform 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. © The Institution of Engineering and Technology 2014.