Practical Microwave Meter for Sensing Moisture and Density of Granular Materials

Abstract

A low-cost microwave sensor for rapid and nondestructive sensing of bulk density and moisture content in granular and particulate materials has been built and tested. The sensor was made with inexpensive, off-the-shelf components and operates at 5.8 GHz. Three permittivity-based algorithms were used to determine simultaneously bulk density and moisture content from dielectric properties measurement. Results obtained for wheat indicate the bulk density can be determined with less than 2% relative error and that moisture content can be determined with a standard error of calibration of 0.5%.