Design of a tunable S-band narrow-band coaxial cavity filter

An electromagnetic model for coaxial cavity filter is theoretically analyzed in this paper. Based on this model, the calculation expressions of cavity coupling factors are derived, and the eigenmode value of each resonator unit is obtained, which are significant parameters to filter design. The 3D electromagnetic simulation software is used to analysis and optimization for the narrow-band cavity filter. Finally, the filter is fabricated and tested. The experiment and simulation results are in coincidence. In comparison with the traditional C-band cavity or waveguide narrow-band band-pass filters, the designed coaxial cavity filter is minimized in size.