Numerical analysis of microwave heating of a dielectric

Microwave heating of a dielectric in a cavity was analyzed numerically with the FDTD method with the aim of devising new methods for reducing uneven heating typical of microwaving. The dielectric was assumed to be water and the frequency of a microwave was taken to be 1 GHz. It was found that the electric field is highly dependent on the position of the dielectric in a cavity. The temperature distribution reflects the profile of the RMS value of the electric field in the dielectric, although there appears to be no effect of the short wavelength typical of the electric field. The heating rate depends on the position of the dielectric. In the case of a higher effective loss factor a microwave decays immediately after entering the dielectric, and the temperature of the interior remains low. These results indicate that the uneven heating is due to at least two causes: standing wave and rapid decay of a microwave. © 2003 Wiley Periodicals, Inc.