Design of wideband bandpass filter using quadruple-mode rectangular cavity resonator

A class of quadruple-mode wideband bandpass filter (BPF) using TM
₁₁
mode, TM
₂₁
mode and two TE
₁₀
degenerated modes is presented in this letter. Two off-centered rods fixed in bottom of intra-cavity and two extended feeding probes in single rectangular waveguide cavity excite those four resonant modes, respectively. The proposed wideband filter achieves the fractional frequency bandwidth of about 29% at the central frequency of 3.1 GHz. Finally, the proposed filter is fabricated using the silver-plated aluminium. The measured results are well matched with the simulated one.