Miniaturized dual‐band filter using triple‐folded substrate‐integrated waveguide resonators

A miniaturized dual‐band filter using novel triple‐folded substrate‐integrated waveguide (TFSIW) resonators is proposed in this paper. The proposed TFSIW is enabled by specially designed folding structures, which leads to significant size reduction. The 2 lowest resonant modes, namely folded TE102 mode and folded TE101 mode in the TFSIW cavity, are utilized to achieve a dual resonance response with a small frequency ratio. To validate the design concept, a dual‐band filter operating at 1.91 and 2.32 GHz is designed, fabricated and characterized. Good agreement has been achieved between the simulation and measurement results. Moreover, the size of the proposed TFSIW resonator has been reduced for 86% compared with the conventional SIW resonator (assuming the same frequency ratio).