Multiphysics Design of a Resonator Tuning System and Dimensionless Formulae

This paper proposes a novel multiphysics design of a resonator tuning system without using conventional tuning screws. The proposed system and method could tune the resonant frequency of coaxial resonators by creating deformation on the cavity lids with imposed pressure. It can significantly optimize extra loss, passive intermodulation (PIM), and power-related issues caused by conventional tuning screws. A comprehensive multiphysics analysis is elaborated to establish the relationship between force, springback, and tuning frequencies. Novel dimensional analysis and dimensionless formulae are first-ever introduced into the tuning process of a microwave resonator. The simulated and measured results have verified the effectiveness of this system and method. Instead of relying on individual experience in the traditional filter tuning process, the optimized solutions and guidelines for practical tuning can be easily achieved under various circumstances using the novel formulae. This system for verification successfully tuned a four-order filter. This method greatly satisfied the industrial demands for cost control and filled the niche in academics upon this non-screw tuning topic. This work also lays a solid foundation for the next-generation automatic filter-tuning system.