Resonances of microwave power absorption in alumina and silicon carbide

Abstract

Power absorption resonances in microwave irradiated low-loss Al2O3 and high-loss SiC have been investigated by determining the normalized average power distribution in the sample slabs. For Al2O3, multiple resonance peaks initially occur at the position following a “half-wavelength (0.5λm) rule”. As temperature increases, this rule becomes invalid due to the attenuation of microwaves with increased dielectric loss. For SiC, however, only one strong resonance peak is observed at the sample thickness of 0.33λm. This indicates that only the sample having the size corresponding to resonance can obtain the maximum power absorption, considerably increasing the microwave heating efficiency.