Compact dual-band balanced SIW bandpass filter with two adjustable closed-passbands

摘要

A new compact multilayer dual-band-balanced bandpass filter (BPF) with two flexibly adjustable closed-passbands based on substrate-integrated waveguide (SIW) resonator is proposed in this letter. Both TE₁₀₂-mode and TE₂₀₁-mode of the resonator are utilised to achieve desired differential mode (DM) transmission and high common mode suppression. Two SIW cavities are properly coupled in the back-to-back form to realise a closed dual-passband-balanced response by virtue of singly one cruciform coupling aperture etched on the ground. Additionally, two pairs of perturbed slotlines are elaborately introduced on the top and bottom layers to perturb the resonant frequencies of TE₁₀₂-mode and TE₂₀₁-mode, realising both adjustable upper- and lower-DM passbands. For demonstration, a prototype dual-band-balanced SIW BPF operating at 12.7 and 15.5 GHz is designed, fabricated and tested. Measured and simulated results are in good agreement, verifying the feasibility of the design concept.