Submitted to: Journal of Microwave Power and Electromagnetic Energy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/21/1996
Publication Date: N/A
Interpretive Summary: Knowledge of the moisture content of cereal grains is important at harvest, when it is going into storage, being traded, or loaded for export, and at various stages in the processing of grain products. The moisture content of grains can be determined rapidly by microwave measurements, and studies are under way for improving the use of such measurements for real-time, on- -sensing of grain moisture content to provide the desired knowledge wherever it is needed. In this research, it is important to have reliable data on the microwave permittivity, or dielectric properties (electrical characteristics) of the grain under various conditions. A technique has been researched and developed that provides reliable information on these dielectric properties of grain. The technique is described and data are presented that show the relationships between these dielectric properties of wheat and important factors such as bulk density and temperature of the grain as well as its moisture content. These new data will be useful in developing improved technology for the rapid nondestructive microwave sensing of moisture content in grain, which, in turn, will provide means for maintaining high quality in grain and grain products for American consumers and export customers as well.
Technical Abstract: Requirements for a free-space mircowave transmission measurement system for determining the permittitivty of grain are analyzed. Experimental verification of these requirements is provided for two cultivars of hard red winter wheat of various densities, moisture contents and temperatures in the frequency range from 10 to 18 Ghz. Uncertainties in the dielectric constant determinaiton are less than +/-1%, and those for the loss factor are less than +/-3%.