Distributed Coherent OFDM-Based Digital Radar for Multistatic UAV-Borne SAR

Recent advances in high-speed analog-to-digital converters enable direct sampling of L-band radar signals, supporting flexible digital architectures and orthogonal frequency-division multiplexing (OFDM)-based processing. This paper presents a distributed digital radar system mounted on uncrewed aerial vehicles (UAVs) for coherent multistatic synthetic aperture radar (SAR) imaging. A primary UAV transmits an OFDM waveform, while secondary nodes simultaneously record both radar echoes and a sidelink reference for offline processing. The mean data rate is significantly reduced by employing an embedded trigger mechanism, and coherency across fast- and slow-time is established digitally without hardware synchronization. A systematic OFDM waveform design for UAV-borne multistatic SAR, together with its implications for onboard data storage, is introduced. Experimental multistatic SAR measurements with two UAVs demonstrate high-resolution imaging and confirm the effectiveness of the proposed concept.