Mirror-Based ArcSAR: Compact System Design and Azimuth Sidelobe Reduction for 360° Imaging of Complex Scenarios

Arc synthetic aperture radar (ArcSAR) employs a rotating arm to drive the antenna along a circular trajectory, and thus, achieves full-azimuth imaging. However, ArcSAR implementation faces critical limitations in size- and efficiency-sensitive uncrewed platforms, as the long rotating arm leads to a large horizontal size and introduces centrifugal issues during rapid rotation. In this article, we propose a compact mirror-based ArcSAR system that utilizes specular reflection to convert the physical rotation radius into a virtual one, thereby bringing benefits to reducing the system's horizontal size and alleviating instability during rapid rotation. In addition, in order to suppress the high azimuth sidelobes, a back projection algorithm tailored for mirror-based BPA based on FPCF (ArcBPA-FPCF) is introduced for full-azimuth 2-D imaging. By employing the azimuth coefficient and norm constraint of normalized range profile projection, the ArcBPA-FPCF enables high-dynamic-range, 360° 2-D imaging of surrounding areas with low additional computational burden. Examples from numerical simulation and indoor and outdoor measurements are presented to demonstrate the effectiveness of the proposed mirror-based ArcSAR system and the performance of the ArcBPA-FPCF in azimuth sidelobes suppression.