MODELS FOR THE MICROWAVE DIELECTRIC PROPERTIES OF GRAIN AND SEED

Based on microwave dielectric properties of wheat, corn, barley, oats, grain sorghum, soybeans, canola, shelled peanuts, and pod peanuts measured over ranges of frequency and moisture content, models are developed for predicting the dielectric constant and loss factor of these commodities. Nearly linear relationships between dielectric properties and log of frequency or frequency and moisture content permit multiple linear regression models to be developed for predicting dielectric constants and loss factors for each kind of grain and seed at 23 degrees C. The models predict dielectric constants with standard errors of 1% to 2% with some up to about 4% for grain and seed at frequencies in the range from 5 to 15 GHz over given moisture ranges. Loss factors are predicted with standard errors of a few percent, but much larger errors can naturally result when loss factors are very small.