Distributed Radar Sounder System: a Novel Approach to Across-Track Resolution Enhancement and Clutter Reduction

Abstract

Spaceborne radar sounders are nadir-looking sensors operating in HF/VHF bands. Their relatively low frequency allows the penetration of the transmitted signals into a given subsurface to infer its geoelectrical properties and composition by analyzing the radar echoes. These type of sensors are affected by unwanted artifacts such as off-nadir clutter mainly resulting from the constraint on the type of deployable antenna which is very often a dipole. Very recent technological advancements open up the possibility of synthesizing very large antenna apertures in HF/VHF band by using small satellites array deployed in suitable orbital formation flying. Accordingly, in this study we propose a novel concept of distributed radar sounder system. The proposed concept is complemented with a mathematical model to predict its performance. The results show that the distributed radar sounder operating in small satellites formation flying is particularly appealing as it can (i) drastically reduce the impact of surface clutter, (ii) increase the across-track resolution, and (iii) increase the signal to noise ratio (or, alternatively, decrease the overall required transmitted power with respect to a traditional radar sounder design).