Miniaturized cavity filters based on concentric dual-coaxial SIR

Two concentric dual-coaxial SIR filters with different structures are proposed. The first is that the upper resonant cap wraps the lower resonant cap; the second is that the cap of the upper resonator no longer wraps the lower resonator. The dual-coaxial quarter-wavelength SIR structure improves the anti-vibration capability of the resonator, and the structure makes full use of the resonator space and improves the unloaded Q value. The insertion loss of the first filter is less than 0.3 dB, and the insertion loss of the second filter is less than 1.5 dB.