Precise Measurement for Temperature Dependence of Dielectric Rod Materials Using an Image-Type Resonator Method (Special Issue on Measurement Techniques for Microwave/Millimeter Wave)

copyright(c)1994 IEICE 許諾番号：07RB0174An image type resonator method is proposed as a method to evaluate precisely the temperature dependence of dielectric material. At first, the temperature coefficients of the resonant frequencies, TC_f are measured separately using the shielded dielectric resonators of three types; that is a parallel plate type, and an image type, and a MIC type resonator. Secondly, an intrinsic temperature coefficient of the resonant frequency TC_<f0>, which is defined as the temperature coefficient of a resonant frequency when all the stored energy is confined inside a dielectric, is estimated from these measured TC_f. Actually, the TC_<f0> values of a sapphire and (Zr・Sn)TiO_4 rod are estimated from the TC_f values measured for the resonators of three types. As a result, for the parallel plate type, the precision of TC_<f0> is about ±0.1ppm/℃. For the image and MIC types, the errors of about ±0.5ppm/℃ in the TC_<f0> values arise from the errors in the linear expansion coefficients of the resonators, rather than from the experimental errors in TC_f. Then, another image type resonator is designed to estimate TC_<f0> within error of ±0.1ppm/℃. In this design, dimensions of the shielding cavity is determined to reduce the influence of the errors in the linear expansion coefficients on precision of the TC_<f0> estimation. Finally, for a (Zr・Sn)TiO_4 ceramic rod, a TC_<f0> value estimated from TC_f measured for the image type resonator is obtained with accuracy of about ±0.1ppm/℃