Effect of frequency alteration regimes on the heating patterns in a solid-state-fed microwave cavity

High-power solid-state sources are expected to be the core elements in efficient controlling characteristics of microwave thermal processing. In this paper, we analyze the effect made by frequency alteration within the 2.4–2.5 GHz ISM band on the patterns of dissipated power density in the processed material. A dual-source rectangular cavity loaded by a rectangular block characterized by different dielectric properties is considered. Two regimes of alteration involving equidistant and resonant frequencies are examined using an finite-difference time-domain model validated against theoretical data on eigen frequencies and corresponding eigen fields. The resulting heating patterns generated after a full cycle of alteration are qualitatively analyzed as superpositions of contributions by the distributions at different frequencies. It is shown that both regimes are capable of effectively mixing up the diverse heating patterns and thus produce more uniform distributions of dissipated power. Alteration over resonant frequencies appears to have the potential for leading to more energy-efficient processes.