G-Band FMCW Doppler Radar for Close-Range Environmental Sensing

Radar systems operating within the 220 GHz atmospheric transmission window are comparatively rare despite the benefits they offer in high angular, range, and Doppler resolutions. Given the growing availability of solid-state signal generation components designed for this frequency range, interest in the sensing potential of this region is increasing. This paper presents the development and characterization of ‘Theseus’, a 207 GHz FMCW Doppler radar designed for sea clutter and marine target characterization but also capable of a large variety of other close-range environmental sensing uses. The radar carrier frequency is tunable between 200-208 GHz with a maximum chirp bandwidth of 2 GHz resulting in a range resolution of 7.5 cm, and a chirp repetition interval (CRI) of $67.59~\mu \text{s}$ giving a maximum unambiguous velocity of $\mathbf {\pm {}5.36}$ ms $^{-1}$ . Several measurement application examples are presented, showcasing a wealth of micro-Doppler and micro-range information gathered from a variety of targets and clutter including sea clutter, humans swimming and running, UAV flight, a plan position indicator (PPI) scan of a terrestrial environment, and rain clutter. Data in this frequency band are very rare in the open literature, and thus the high range and Doppler resolution measurement capabilities of this radar present an opportunity to expand the knowledge in this area.