Study on measurement method of permittivity for low-loss materials using microstrip ring-resonator

We have developed a new permittivity measurement method for low-loss materials using a microstrip ring-resonator. This method can be used over broad-bandwidth nearly equal to operating bandwidth of transmission lines. We have measured S21 of the developed circuit and convert them to time-domain spectrums. By analyzing equally-spaced peaks, we estimated dielectric properties of a substrate material. Estimations of the proposed method are consistent with those of the transmission/reflection method within uncertainties of two methods.