空气湿度微波谐振腔测量方法

提出一种通过微波谐振腔测量气体介电常数实现空气湿度连续测量的方法，并给出计算不同温度和湿度下空气等效介电常数的模型，设计出作为流动空气湿度传感器的两端采用开放同心圆环结构的特殊结构的谐振腔，对制作的谐振腔进行了气动特性仿真及S参数测量。仿真和测量结果表明：该结构的谐振腔适合于流动气体湿度的在线测量。研制了适用于空气湿度在线测量的微波测量系统。利用此系统对该文设计产生的饱和湿空气环境进行了测量，分析了测量结果和理论结果间的误差。该测量系统在29~38℃范围内能够实现±1.5%空气相对湿度的测量精度。

Method for Air Humidity Measurement Based on Microwave Resonant Cavity

A microwave resonant cavity based method for wet air humidity measurement is presented in this paper. The calculation model of equivalent dielectric constant of wet air at different temperature and humidity is established. A specially structured resonant cavity with annular grid at its both ends was designed for the humidity measurement of flowing wet air. The pneumatic characteristic of the cavity was simulated and the S parameter of it was measured. The simulation and measurement results show that it is especially suitable for the online measurement of flowing wet air humidity. The measurement system has been developed and used to measure the saturated wet air which is especially produced for studying the performance of the system. The experimental data and theoretical value are compared and the reasons for deviation between them are analyzed. The accuracy of the wet air humidity measurement can reach ±1.5% in the temperature range of 29~38 ℃.