THz Imaging Radar for Standoff Personnel Screening

TLDR

Future multi‑beam THz transceivers promise even faster imaging speeds. The paper summarizes the NASA JPL 675 GHz imaging radar, highlighting design features that enable fast, reliable through‑clothes detection of concealed objects. The radar uses FMCW with a 30 GHz bandwidth, software calibration, heterodyne RF architecture, and an optical design that together deliver sub‑centimeter resolution, low‑noise detection, and a 1 Hz real‑time imaging frame rate.

Abstract

A summary of the NASA Jet Propulsion Laboratory's 675 GHz imaging radar is presented, with an emphasis on several key design aspects that enable fast, reliable through-clothes imaging of person-borne concealed objects. Using the frequency-modulated continuous-wave (FMCW) radar technique with a nearly 30 GHz bandwidth, sub-centimeter range resolution is achieved. To optimize the radar's range resolution, a reliable software calibration procedure compensates for signal distortion from radar waveform nonlinearities. Low-noise, high dynamic range detection comes from the radar's heterodyne RF architecture, low-noise chirp source, and high-performance 675 GHz transceiver. The radar's optical design permits low-distortion fast beam scanning for single-pixel imaging, and a real-time radar image frame rate of 1 Hz is now possible. Still faster speeds are on the horizon as multi-beam THz transceivers are developed.