Multi-Static Multi-Band Synthetic Aperture Radar (SAR) Constellation Based on Photonic Processing

Multi-static SARs from low earth orbits (LEO) allow single-pass high-resolution imaging and detection of moving targets. A coherent MIMO approach requires the generation of multi-band orthogonal signals, the fusion of which increases the system resolution. Up to now the synchronization capability of SAR signals of different satellites is critical. Here we propose the use of photonics to generate, receive and distribute the radar signals in a coherent multi-static SAR constellation. Photonics overcomes issues in implementation of MIMO SAR, allowing for flexible multi-band signals generation and centralized generation in a primary satellite with coherent distribution to all the secondary satellites of the SAR signals through FSO links. The numerical analysis shows the proposed system has noise equivalent sigma zero (NESZ) <−31.6 dB, satisfying the SAR system requirements. An experimental proof of concept based on commercial bulk devices, for both radar signal up and down conversion is implemented, demonstrating the system functionality.