Wide-field circular SAR imaging: An empirical assessment of layover effects

Abstract

In circular synthetic aperture radar (CSAR), targets are usually scanned over the complete azimuthal aperture of 360°. A major challenge inhibiting successful CSAR image production is encountered in two-dimensional imaging of relatively large scenes (i.e. wide-field scenarios). For such cases, the spatially variant radar signature gives rises to image degradations known as layover effects. In this paper, the imaging results for hypothetical and real complex targets using their CSAR data at C band are demonstrated to characterize these effects. In real experiments, a ground-based, outdoor CSAR system is exploited thanks to the circular balcony of a building that provides 270° view of targets. A spherical back-projection algorithm is used to focus near-field data and the reconstructed images are also cleaned out from clutter to more easily visualize the layover artifacts.