Analysis of electromagnetic fields using the finite‐difference time‐domain method in a microwave oven loaded with high‐loss dielectric

There are few examples for three-dimensional electromagnetic analysis for a high-loss dielectric water load which has one of the highest relative permittivities of 80.4 among food items placed in a microwave oven. In this paper, the three-dimensional finite-difference time-domain (FD-TD) method is used for the analysis of the electromagnetic field inside the water load. In the fundamental investigation using the high-loss dielectric loaded rectangular waveguide, it is confirmed that the FD-TD numerical results with Yee's cell pitch which is set at about one-tenth the wavelength reduced within the dielectric, agree almost with the exact solution based on the transmission theory. After the confirmation of the validity, the electromagnetic field within a water load placed on a metal turntable is analyzed. The water load has a cylindrical shape with a diameter of 64 mm and a height of 80 mm. As a result, the reduction of heating unevenness by the turntable can be predicted visually and quantitatively. In this analysis, the steady-state solution can be obtained after 300 iterations while the heating pattern is stabilized after 100 to 200 iterations.