Temperature compensated cavity resonator as integral part of a LTCC baseplate

A new concept for compensating the influence of thermal expansion on the resonance frequency of cavity resonators is presented. A cylindrical resonator made of a material with a given coefficient of thermal expansion is covered with a dome-shaped structure made of a material with a higher coefficient of thermal expansion. Although both parts of the resonator structure contribute to the increase of the resonator volume with temperature, the effect on the TM₀₁₀ resonance mode can be designed such that the resonance frequency is stable. This concept is applied to a resonator suitable for integration into a LTCC baseplate.