Tomographic Processing of Synthetic Aperture Radar Signals for Enhanced Resolution

Abstract

Spotlight-mode synthetic aperture radar imaging is studied from the viewpoint of tomographic signal processing which allows the relaxation of the nearly-universal assumption that plane waves pass over the ground patch. This allows high-quality image reconstruction in the face of arbitrary amounts of wavefront curvature such as would be present when the angle subtended by the ground patch, as seen by the radar, is not small. One such application is wide-area surveillance. A meth- odology is used which has the benefits of a wideband transmitted signal (impulse) and a sensible simulation. Image reconstruction algorithms are developed for monostatic and bistatic systems. Simulation results using these algorithms compare favorably with baseline simulations which use a more conventional algorithm operating on data which do not embody the effects of wavefront curvature. Comments on system design and computational implementation are made as necessary. A new set of problems which appear to benefit from the tomographic viewpoint is posed. This work may also find applications in some forms of reflection tomography.