Humidity sensor based on substrate integrated waveguide reentrant resonant cavity

A humidity sensor based on a substrate integrated waveguide reentrant resonant cavity comprises a substrate integrated waveguide reentrant resonant cavity and a coplanar waveguide feeder line. The reentrant resonant cavity is formed by vertically stacking four dielectric substrates, and an intermediate dielectric layer of each dielectric substrate is etched with a plurality of metallized through holes that are uniformly distributed outside the resonant cavity and on both sides of the feeder line. The intermediate dielectric layers of the second dielectric substrate and the third dielectric substrate are both etched with fan-shaped grooves, and the bottom metal layer of the second dielectric substrate and the top metal layer of the third dielectric substrate are etched with L-shaped strip grooves. In the invention, a stacking technique is applied in the substrate integrated waveguide reentrant resonant cavity, so as to ensure high quality factor of the resonant cavity and greatly reducerelative size of the res