Continuous measurement of moisture in nonconducting materials

A microwave-based system has been developed for the continuous measurement of the moisture in nonconducting materials. The system was implemented on conveyor belts carrying coarse coal. To obtain a reliable measurement for this application, several other factors that influence the microwave technique were investigated. These factors are the mass per unit area, the ash content, and the temperature. The measurement of these factors makes possible the general characterization of the coal, which is important for optimizing the utilization of the coal in many different applications. An experiment was conducted on a network analyzer to determine the relationship between the moisture content of the coal and the attenuation as well as the phase shift of the microwave signal. A double-balanced mixer and microwave detectors were used to measure these parameters