Multiphysics Design Methodology for U-Band Temperature-Compensated Bandstop Filters

This article proposes a novel multiphysics design methodology for a U-band bandstop waveguide filter with temperature compensation (TC). A bimetal TC structure is first implemented to a bandstop filter in such high frequencies for working in a wide temperature range (−20 °C ∼ 70 °C) with little frequency drift. The synthesis and design of the bandstop filter are detailed. The proposed methodology mainly guides the design of the bimetal actuator from geometry, multiphysics, post-production and theoretical promotion. The geometric derivation for the bimetal reactions is elaborated and leads to a simplified equivalent model. Multiphysics analysis, including temperature, thermal stress, and electromagnetic field, is co-elaborated in the design process. Considering the fabrication errors, a post-production adjustment method for the TC structure is designed for practical use. Dimensionless formulae are introduced to provide general design guidelines and rules for filters with different dimensions and TC demands. Finally, a sixth-order temperature-compensated bandstop filter is manufactured and tested in temperature cycles. The measurements have validated the theoretical and simulation results.