Influence of the magnetron operating frequency on the results of microwave heating

In typical simulations of heating processes in household microwave ovens it is assumed that the frequency of the magnetron stays constant at its nominal value. In reality, due to manufacturing variations, load parameters, and the magnetron temperature, frequency differences or jumps of 50 MHz may occur. This publication shows coupled electromagnetic and thermal simulations of microwave heating phenomena in household microwave ovens. Several analyses are performed for a static load at various frequencies in order to assess possible effects of frequency changes on the heating patterns. A novel FDTD regime with moving loads and frequency tuning is then applied to demonstrate that the load rotation typically implemented in domestic microwave ovens largely equalizes the patterns at different frequencies. Both, the total absorbed power and the power distribution in the load are studied.