Frequency and Temperature Dependence Measurements of Complex Permittivity of Dielectric Rods Using Some TM0m0 Modes in a Circular Cavity

This paper, at first, discuss the availability of a cavity resonance method using the resonance frequencies of some TM_0m0 modes in a circular cavity to measure the frequency dependence of a dielectric rod sample. The influence of sample insertion holes to the measurement are estimated accurately on the basis of the rigorous analysis by the Ritz-Galerkin method. Some dielectric rod samples were measured by using two modes TM₀₁₀ and TM₀₂₀ hi each of two cavities with different heights. The measurement precision for the relative permittivity was improved within 0.3 %, compared with 3 to 7 % in the perturbation method. Then one of the cavities was set in an environmental test equipment and the temperature dependences of dielectric rod samples were measured. As a result, the present method is useful to measure the frequency and temperature dependences of dielectric rod samples.