Millimeter wave measurements of temperature dependence of complex permittivity of dielectric plates by the cavity resonance method

A circular cavity resonance method is discussed to measure the temperature dependence of complex permittivity of dielectric plates in the millimeter wave region. A cavity structure is cut in the middle of the length. A plate sample is placed between these two halves and is clamped with clips. The fringe effect can be estimated accurately from the rigorous analysis based on the mode matching technique. By this method, the frequency dependence of the complex permittivity for PTFE plates and new organic compound plates were measured in the frequency range between 10 and 50 GHz at room temperature, and the temperature dependence for these plates were measured at 48 GHz. It is verified that this method is useful as precise measurements of the complex permittivity of low loss dielectric plates in the microwave and millimeter wave regions