Heating Concentrations of Microwaves in Spherical and Cylindrical Foods

A comprehensive and systematic study of microwave heating concentration, as in spherical and cylindrical materials, is presented based on theoretical analysis and numerical investigations for both plane waves (Part One) and cavity standing waves (Part Two). In part one, along with penetration depth, the wavelength is introduced for characterization of microwave heating of foods. Based on theoretical analysis, the distributions of power density in radial direction are studied for various groups of foods with a radii range from 0.5 to 13.5 cm. At 2.45 GHz, the focusing areas are pronounced in terms of dielectric properties and the radii are then presented as heating diagrams. For example, the smallest radius that can lead to heating concentration of microwaves is 0.5 cm for any food material, and the upper limit of the radius that incurs center heating for unfrozen foods is more than 13.5 cm.