Microwave Moisture Sensor for Grain and Seed

摘要

A low-cost microwave sensor for nondestructive, rapid sensing of moisture content in granular and particulate materials has been built and tested. The sensor operates at a single frequency of 5.8 GHz and uses the principle of free-space transmission for moisture determination from measurement of the dielectric properties of the material. A unified calibration algorithm was used for moisture determination independent of bulk density and independent of the material type. Results for wheat and soybeans show that moisture content can be determined in either material from a single moisture calibration equation with a standard error of calibration of 0.5%. The low price, simplicity of use, and level of accuracy of the proposed sensor can provide an opportunity for widespread integration of microwave sensing technology in numerous industries dealing with granular and particulate materials, including food and agriculture, pharmaceuticals, mining, and construction.