Reduced Rank Fast-time STAP using the Multistage Wiener Filter in Multichannel SAR

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 partially reject the interference components. Previous studies have shown that derivative constraints when combined with fast-time taps can provide improved HC suppression 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 using a constrained multistage Wiener filter (MWF).