A Sparse Signal Representation-based Approach to Image Formation and Anisotropy Determination in Wide-Angle Radar

We consider the problem of jointly forming images and determining anisotropy from wide-angle synthetic aperture radar (SAR) measurements. Conventional SAR image formation techniques assume isotropic scattering, which is not valid with wide-angle apertures. We present a method based on a sparse representation of aspect-dependent scattering with an overcomplete dictionary composed of elements with varying levels of angular persistence. Solved as an inverse problem, the result is a complex-valued, aspect-dependent response for each spatial location in a scene. Our formulation leads to an optimization problem for which we develop a tractable, graph-structured approximate algorithm. We present experimental results on realistic electromagnetic simulations demonstrating the effectiveness of the proposed approach.