A resonant cavity for high-accuracy measurement of microwave dielectric properties

Abstract

This paper demonstrates that, along with the change in resonant frequency, the coupling coefficient between a resonant cavity and a transmission line will be altered once a dielectric sample is inserted into the cavity. These changes affect the measurements of the Q factors, and thus cause uncertainties in the permittivity measurements of dielectric samples. An X-band TE112 mode cavity is designed to overcome the uncertainties in the permittivity measurements, with which the Q values can be measured at the same resonant frequency and the same coupling conditions before and after the introduction of a dielectric sample.