Two differential open resonator techniques for measuring dielectric constants of thin films on substrates

In this work we describe two methods developed for measuring dielectric constants of thin films deposited on a substrate. The samples are placed into the classical open Fabry-Perot resonator, and differential approach is used based on measurement of resonant frequency shifts caused by the presence of the film. One method utilizes a spherical resonator, while the other method utilizes a hemispherical resonator. Experimental realization of the methods has been carried out at frequencies of 100-143 GHz.