A Modified Formula for Calculating Dielectric Properties of Granular Agricultural Products in the Microwave Band

Abstract

Dielectric properties are important characteristic parameters in the microwave-assisted application of hygroscopic agricultural media. To break through the limitation of traditional general effective medium (GEM) formula and develop the new calculation formula suitable for agricultural products, a modified formula, that is, modified general agricultural products effective medium (abbreviated as MGAPEM) formula, was presented in this study for the dielectric property calculation of granular agricultural products in the microwave band. The correctness, validity, and accuracy of MGAPEM formula were verified by using literature and experimental measurement data. Results show that the maximum errors of the dielectric constant and dielectric loss factor are 0.42% and 0.98%, respectively, in the conditions of microwave frequency (2.0–12.2 Ghz) and moisture content (2.0%-19.7%, wet basis). The accuracy of MGAPEM is higher than some traditional theoretical formulas. The MGAPEM formula provides a theoretical formula for the dielectric property analysis of granular agricultural products in the microwave band at room temperature (24℃).