Some Recent Developments of Microwave and Millimeter-wave Sensors

We report on some recent developments on microwave and millimeter-wave sensors, including an ultra-wide band (UWB) impusle sensor, microwave and millimeter-wave stepped-frequency sensors, and a millimeter-wave interefrometric sensor. These sensors are completely realized usign microwave integrated circuits (MICs) and microwave monolithic integrated circuits (MMICs). The UWB impulse sensor operates over multiple pulse durations from 450 to 1170 ps with 5.5-GHz radio-frequency bandwidth. It performs well through tests of various samples, demonstrating its usefulness for subsurface sensing. The microwave stepped-frequency sensor operates from 0.6 to 5.6 GHz and has been used to assess accurately pavement samples for subsurface sensing applications. The millimeter-wave stepped-frequency sensor operates from 29.72 to 37.7 GHz and has demonstrated abilities in surface and near-surface sensing, including profile mapping, liquid-level monitoring, and anti-personnel mine locating. The millimeter-wave interferometric sensor operates at 35.6 GHz and has demonstrated its multi-functional capability for measurement of displacement and low velocity. These developed microwave and millimeter-wave sensors are attractive and useful for various surface and subsurface sensing applications.