Clutter Discrimination by Estimation of Direction of Arrival in Spaceborne Distributed Radar Sounders

Spaceborne radar sounders are nadir-looking sensors devoted to subsurface investigations. The data interpretation of these sensors can be severely hindered by clutter originating from surface off-nadir reflections. Recently, the concept of distributed radar sounding has been proposed for synthesizing a narrow radar antenna beam with clutter suppression capability. The antenna beam is effectively synthesized by deploying an array of orbiting sensors in formation flight. In this paper, we assess the capability of distributed radar sounding to further discriminate clutter from subsurface returns by exploiting Direction of Arrival (DOA) estimation techniques. Accordingly, we propose an approach to design and evaluate the distributed radar sounder DOA estimation performance. The theory is complemented by radar simulations of several acquisitions over Greenland. The simulations confirm that clutter discrimination through DOA estimation is an effective approach for further improving the array capability in disam-biguating subsurface echoes from surface ones.