The closed cavity method is proposed to measure the frequency temperature coefficient (τf) of a dielectric resonator. The τf 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 τf polynomial are discussed in detail. The intrinsic temperature coefficient of resonant frequency (τf0) is introduced to improve the measurement precision. Resonators made of BaO-TiO2-Sm2O3 and (Zr0.8Ti0.2)TiO4 ceramics with Teflon and alumina as supports were measured. The results show that the τf 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 τf0, the variation is less than 2 ppm/˚C.
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