Temperature Stable Dielectric Microwave Resonators for High Power Applications

Temperature stabilisation was obtained by combining two dielectrics with opposite temperature coefficients of dielectric permittivity to a composite resonator. Single crystals of LiNb03 were used as the part with positive coefficient, while the other part consisted of especially developed ceramics. S-band resonators of both "sandwich"- and "coaxial" type were made with Qo-values of 5000 - 6000 and an effective ¿ = 54-59, which is higher than any ¿-value previously obtained for temperature compensated dielectrics. Resonators with a resulting temperature coefficient of frequency 1/f (df/dT) = 6 - 8 ppm/°C in the range of 10 - 50°C were tested with CW-power up to 80 W with very satisfying results.