A microwave system for humidity measurements

A microwave humidity measurement system based on microwave resonance has been developed at TÜBİTAK UME (National Metrology Institute of Turkey). This technique is based on microwave resonance frequency detection of a cavity that is sensitive to permittivity of air and water content. We have designed a copper microwave cavity resonator, a microwave electronics and a software to measure relative permittivity of air. Experimental results show good agreement with traditional humidity measurements in the range from 25% RH to 80% RH.