Temperature Coefficient Measurement of Microwave Dielectric Materials Using Closed Cavity Method

Abstract

The closed cavity method is proposed to measure the frequency temperature coefficient (τ f) of a dielectric resonator. The τ f polynomial, which is linear combination of the temperature coefficient of relative dielectric constant and the linear expansion coefficient of the dielectric and cavity, is given. The coefficients of τ f polynomial are discussed in detail. The intrinsic temperature coefficient of resonant frequency (τ f 0) is introduced to improve the measurement precision. Resonators made of BaO-TiO 2-Sm 2 O 3 and (Zr 0.8 Ti 0.2)TiO 4 ceramics with Teflon and alumina as supports were measured. The results show that the τ f values of the same resonator with above supports are different, and the measured variation between them is more than 3 ppm/ • C. Using the concept of τ f 0 , the variation is less than 2 ppm/ • C.