Single‐ and triple‐band bandpass filters using novel perturbed isosceles right‐angled triangular SIW cavities
Junjie Zhang, Qing Liu, Dongfang Zhou, Dewei Zhang
Abstract
Abstract Herein, a rigorous derivation of an isosceles right‐angled triangular (IRT) metallic cavity is analysed. Then, the transverse field components in the IRT substrate‐integrated waveguide (SIW) cavity are derived, and the expression of the resonant frequencies can also be obtained. Then, a novel perturbed IRT SIW cavity is proposed, which is based on the characteristics of resonant modes in IRT SIW cavity and the capacitive‐loading technique. Three prototypes were designed to verify the validity of the derivation and analysis in this study. First, a dual‐mode single passband filter was implemented using the perturbed modes TE 102 and TE 202 . Next, two tri‐mode triple‐band bandpass filters (BPFs) using the perturbed modes TE 101 , TE 102 and TE 202 are proposed, synthesised, verified and measured for demonstration, including a second‐order direct‐coupled one which operates at 8.02, 11.44 and 12.52 GHz, and a fourth‐order direct‐coupled one which operates at 7.7, 11.0 and 12.1 GHZ. The measured curves agree well with the simulated ones. Very compact circuit sizes and excellent filtering performances have been achieved for the three prototypes.