Absorber Impedance Matching in Microwave Heating

A mathematical function for evaluating the impedance matching degree of microwave absorbers was proposed to increase microwave absorption in microwave heating. For nonmagnetic dielectrics, the value of the function depends on the ratio of the sample thickness to the microwave penetration depth and the dielectric loss tangent phase angle. The maximum sample thickness corresponding to perfect impedance matching will decrease with increasing dielectric loss tangent phase angle, and thus, the highest microwave absorption can be achieved. The calculations of impedance matching for hematite indicate that hematite of less than 0.10 m thickness can obtain the maximum absorption throughout the microwave heating process. (C) 2012 The Japan Society of Applied Physics