FMCW Inverse Circular Synthetic Aperture Radar Using a Fast Time-Domain Reconstruction

Abstract

This article proposes a millimeter-wave inverse circular synthetic aperture radar system and a fast time-domain wavefront reconstruction (TDWR) algorithm for near real-time, low-cost imaging of packages and concealed objects. An 80-GHz frequency-modulated continuous-wave (FMCW) radar illuminates targets on a high-speed rotating turntable driven by a precision motor system. Data are collected over a synthetic circular aperture and processed to form high-resolution images of targets. To achieve real-time operation, a fast and accurate time-domain reconstruction and deconvolution imaging algorithm is proposed. The image formation is based on frequency-domain wavefront reconstruction for circular arrays that is adapted to FMCW radars by proposing an analogous time-domain approach. Next, an analytical form for the point spread function (PSF) of circular synthetic aperture radars (CSARs) is derived and used to speed up the recursive deconvolution for improved image quality. The system and reconstruction algorithm are applied to an experimental setting of detecting a concealed handgun in a package. Several practical considerations are discussed to ensure that the reconstruction and deconvolution can be applied successfully in retrieving good quality images. The experimental datasets and codes are available at https://adityamuppala.github.io/research/.