MirrorSAR: A fractionated space transponder concept for the implementation of low-cost multistatic SAR missions

This paper introduces a new fractionated radar concept that offers the potential to significantly reduce the costs of future multistatic SAR missions. The key idea is based on a radical simplification of the receiver satellites by limiting their main functionality to a kind of microwave mirror (or space transponder) which redirects the incoming radar echoes to one or more transmitters. There, the routed signals are coherently demodulated using the same local oscillator that was used before to generate the radar pulses. This MirrorSAR concept not only saves the hardware for coherent demodulation, data storage, downlink and digital control within the receiver satellite, but also avoids the need for a bidirectional phase synchronization link between the transmitter and receiver, as it is currently employed in TanDEM-X. As the requirements for the receiver satellites are significantly reduced in this approach, it becomes possible to use low-cost platforms such as those currently being developed in the NewSpace context and to scale their number without any cost explosion. This will ultimately pave the way for novel remote sensing applications like multi-baseline SAR interferometry and single-pass tomography.