Design of Millimeter-Wave Dual-Band Filter Based on Half-Mode Groove Gap Waveguide

In this paper, a millimeter-wave dual-band bandpass filter based on half-mode groove gap waveguide is presented. The proposed filter consists of a half-mode gap waveguide resonant cavity (HMGWRC), two waveguide coupled irises, and a pin-loaded cover plate. The HMGWRC initially operates at two half-TE 103 and half-TE <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${}_{201}$</tex> modes. The two higher-order modes are perturbed by adjusting the heights of the two pins beneath the HMGWRC, generating two additional degenerate modes <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{TE}_{103}$</tex> ' and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{TE}_{201}$</tex> ' near the resonant frequencies of the two original higher-order modes. A dual-band filter with two dual-mode passbands is realized by simultaneously exciting these four resonant modes through two waveguide coupled irises. The first passband operates at 26.425 GHz with a 3 dB relative bandwidth of 3.9 %, while the second passband operates at 29.77 GHz with a 3 dB relative bandwidth of 11.7 %. The proposed filter can be applied to 5 G millimeter-wave communications.