High Frame-Rate Imaging Using Swarm of UAV-Borne Radars

High frame-rate imaging of synthetic aperture radar (SAR), known as video SAR, has received much research interest these years. It usually operates at extremely high frequency and even THz band as a technical tradeoff between high frame rate and high resolution. As a result, video SAR system always suffers from limited functional range due to strong atmospheric attenuation of signals. This article attempts to present a new high frame-rate collaborative imaging regime in the microwave frequency band based on a swarm of unmanned aerial vehicles (UAVs). The spatial degrees of freedom are employed to shorten the synthetic time and thus improve the frame rate. More specifically, the long synthetic aperture is split into multiple short subapertures, and each UAV-borne radar implements short subaperture imaging in a short time. Then, the accelerated fast back-projection (AFBP) algorithm is employed to fuse multiple subimages to produce an image with high azimuth resolution. To implement the collaborative working of swarm of UAV-borne radars, a suitable orthogonal waveform is selected and a useful spatial configuration of the swarm is designed to compensate for the effect of the orthogonal waveform on imaging. Simulation results have been presented to highlight the advantages of collaborative imaging using a swarm of UAV-borne radars.