Magnetic Loss in Microwave Heating

A simplified equation for quantifying magnetic loss in materials under microwave irradiation was derived to demonstrate the importance of magnetic loss in microwave heating. The magnetic losses for five ferrites, namely, BaFe12O19, SrFe12O19, CuFe2O4, CuZnFe4O4, and NiZnFe4O4 were calculated at 2.45 GHz using the derived equation. It is found that magnetic loss is up to approximately four times greater than dielectric loss in the microwave heating of ferrites. These results, through the calculations, theoretically demonstrate that magnetic dielectric materials are heated much faster in a magnetic field than in an electric field of the microwave applicator. (C) 2012 The Japan Society of Applied Physics