Measurement of Temperature Dependent Permittivity for Thin Material during Microwave Heating

In measuring complex permittivity for a thin material in microwave frequency, to apply a cylindrical cavity resonator is one of the best ways. To apply microwave heating using the cavity resonator, it becomes possible to measure temperature dependency of the complex permittivity of material. In this paper, TE₀₁₁ cylindrical cavity is designed at 2.45 GHz and the system to measure temperature dependence for thin material is fabricated. The cavity allows high microwave power excitation and it can heat the sample simultaneously with the measurement. The characteristics of material as the temperature are measured by measuring transmission coefficient of the cavity with high power transmission. The result of the complex permittivity show the relative loss of thin organic material is very sensitive to the temperature.