Near-Field 2-D SAR Imaging by Millimeter-Wave Radar for Concealed Item Detection

Recent progress in complementary metaloxide semiconductor (CMOS) based frequency-modulated continuous-wave (FMCW) radars has made it possible to design low-cost and low-power millimeter-wave (mmWave) sensors. As a result, there is a strong desire to exploit the progress in mmWave sensors in wide range of imaging applications including medical, automotive, and security. In this paper, we present a low-cost high-resolution mmWave imager prototype that combines commercially available 77 GHz system-on-chip FMCW radar sensors and synthetic aperture radar (SAR) signal processing techniques for concealed item detection. To create a synthetic aperture over a target scene, the imager is constructed with a two-axis motorized rail system which can synthesize a large aperture in both horizontal and vertical directions. Our prototype system is described in detail along with signal processing techniques for two-dimensional (2-D) image reconstruction. The imaging examples of concealed items in various scenarios confirm that our low-cost prototype has a great potential for high-resolution imaging tasks in security applications.