Reduced rank interference suppression for multichannel SAR

Abstract

Large regions of a Synthetic Aperture Radar (SAR) image can potentially be destroyed by an airborne broadband jammer. Jammer components include both the direct-path and multipath reflections from the ground, known as hot-clutter (HC) or terrain scattered interference. Using multiple antennas on a SAR provides spatial degrees of freedom and allows for beamforming to reject the direct-path signal. Previous studies have shown that derivative constraints when combined with fast-time taps can suppress HC while maintaining a reasonable SAR image. This approach however requires an expensive matrix inverse and may not be implementable in real time. This paper therefore presents a fast-time Space Time Adaptive Processing (STAP) algorithm with a reduced rank constrained Generalised Sidelobe Canceller (GSC).