A Multi-Wavelength Microwave Photonic Transponder for Future Synthetic Aperture Radar Satellite Formations

In this paper a new microwave photonic concept for enabling bi- or multi-static spaceborne synthetic aperture radar (SAR) systems is presented. In the concept, there is one master satellite and one or more transponder satellites. The master transmits a radar signal and the function of the multi-wavelength microwave photonic transponder is to relay multiple antenna array channels, which are fed by the radar echos, back to the master. This is achieved leveraging a phase-preserving modulation, wavelength division multiplexing (WDM) and freespace optics (FSO). The modulation format used allows the system to avoid synchronizing the clocks of the platforms with each other. Preliminary results for gain, noise performance, and dynamic range are calculated and the delay knowledge achievable for the system is discussed. Finally, there is a discussion on future research and some concluding remarks.