A feasibility study of a universal calibration method for nondestructive real-time sensing of moisture content in granular materials is described. The principle is based on measurement of the dielectric properties of granular materials at microwave frequencies and the use of a calibration Junction that is expressed in terms of these properties to predict moisture content from a single moisture calibration equation. Effectiveness of this method is shown for three granular materials exhibiting significant structural and compositional differences: wheat, oats, and soybeans. The resulting single moisture calibration equation, based on measurements of the dielectric properties at 9.46 GHz and 24 ℃, provides moisture content in all three materials with a standard error of calibration of 0.46 moisture content, wet basis.
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