Influence of the coupling between a cavity and a transmission line on the measurement of complex permittivity by the resonant cavity perturbation method

The real part of permittivity can be evaluated at 2.247 GHz by the resonant cavity perturbation method in strong coupling state up to -3.7 dB of coupling that has not been investigated. The imaginary part of the permittivity can be evaluated reliably up to -14 dB of coupling. In the resonant cavity perturbation method, the influence of the coupling on blank and sample loaded cavity are compensated up to -14 dB of |S21|. The possibility of measuring high loss materials was shown by the measurement of Au coated ceramic rod.