Extra-cavity perturbation method for the measurement of dielectric resonator materials

An extra-cavity perturbation method is presented to determine the complex permittivity, epsilon(r)'(1 - j tan delta), of a high dielectric constant materials from measurements of frequency (or length) shift and change in the Q factor of the cavity when a sample is inserted into an evanescent guide outside the TE01n cylindrical cavity resonator. Fundamental principles and the optimum sensitivity and accuracy of the measurements are discussed. Experimental results for E-r', tan delta, and tau(epsilon) (temperature coefficient of epsilon(r)') on ceramics (Ba1-xSrx)Ti4O9 and BaO-PbO-Nd2O3-TiO2 are given. The results obtained using the present method and a traditional dielectric resonator method agree within\Delta epsilon(r)'/epsilon(r)'\ less than or equal to 5.5%. (C) 1997 American Institute of Physics.