Multiplatform Image Synthesis for Distributed Synthetic Aperture Radar in Long Baseline Bistatic Configurations

The capability to synthesize an image of improved performance combining both in amplitude and in phase a stack of low-performance bistatic synthetic aperture radar (SAR) images is qualifying to enable future missions based on the clusters of nanosatellites or CubeSats. This is called multiplatform image synthesis and it is investigated in this article with reference to the challenging scenario in which a cluster of formation-flying receiving-only units realizes a distributed SAR (DSAR), collecting bistatic echoes of signals transmitted by a monostatic SAR that is used as an opportunity illuminator. The article presents a solution for DSAR processing that combines the generality of time domain focusing with the flexibility of beamforming in the spatial domain. The proposed processing scheme is used as a training ground to develop indices for performance characterization under different system parameters, such as pulse repetition frequency and separations among different platforms.