A new method for microwave dielectric measurement of low loss ceramics

In this paper a novel resonant method was proposed for the determination of dielectric constant and loss tangent of low loss ceramic materials used for dielectric resonators at microwave frequencies. The details of the design and fabrication of the cavity, the input and output coupling transmission lines and the substrate were discussed. The radial mode matching (RMM) technique was used to determine the exact frequencies of this resonant configuration as a function of the permittivity of the sample. And the relation between the loss tangent of the sample and the unloaded quality factor (Ql) of this structure was obtained on the basis of the electromagnetic field distribution. Some numerical results for the direct and inverse problems were presented to validate these relationships. The absolute uncertainties of the measurement were presented. Lastly the procedure of measurement was discussed.