Dual-Band, Dual Independently-Tunable Near-Field Focus Metasurface for Advanced Radar Bio-Sensor

The demand for advanced, non-invasive blood glucose monitoring technologies has driven extensive research into radar sensing applications. This paper introduces a dual-band, dual independently-tunable near-field focus metasurface designed to enhance the performance of millimeter (mm)-wave radar-based bio-sensor. This metasurface enables dual focusing of absorbed power within human skin, achieved through a phase-synthesized analysis of the metasurface array, where each focal point is controlled by a distinct frequency band within the radar spectrum. The integration of the proposed metallic slot metasurface with commercially available Infineon radar TX/RX antennas results in a 14.7 dB and 12.4 dB increase in Poynting power density at two distinct points within a human skin phantom model, along with an increase in radar-received power by 11 dB and 12.7 dB at 58.5 GHz and 61.7 GHz, respectively, significantly enhancing the radar's bio-sensing capabilities.