Design and Experiment of a Hollow Structure Microwave Humidity Sensor

Humidity is a critical parameter for microwave remote sensing. The method of the microwave resonator to measure humidity is fast, accurate, and real-time. In this paper, a microwave humidity sensor based on the substrate integrated waveguide resonator is designed. The sensor uses a hollow FR-4 substrate structure, which reduces the loss of FR-4 substrate at high frequency and improves the sensitivity of the sensor. The design has a simple structure, low cost, and simplifies the process of the humidity sensor based on thermodynamics and optics. Simulation and experiment results show that the sensor can measure the humidity well.