Microwave heating based on solid-state generators: New insights into heating pattern, uniformity, and energy absorption in foods

Microwave (MW) ovens, powered by traditional magnetrons, often produce unpredictable heating patterns in foods due to their wide and random frequency spectrum. This study investigated the potential of solid-state (SS) MW generators to overcome this limitation. The frequency spectra of the SS generator were measured, and computer simulation and experimental methods were used to analyze the standing wave and heating patterns within foods. The influence of SS frequency on MW power reflection and heating uniformity was also examined. The results show that the SS generator's operating frequency bandwidth was less than 0.1 MHz, approximately 1/500th that of magnetrons. This narrow and stable bandwidth enabled the SS-powered cavity to support a single standing wave pattern (mode), resulting in stable and predictable heating patterns in foods. Moreover, adjusting SS frequencies could minimize MW power reflection, and the use of complementary SS frequencies could improve MW heating uniformity. This study provides fundamental insights into SS MW heating and offers guidance on controlling SS frequency to improve heating performance.