Single? and triple?band bandpass filters using novel perturbed isosceles right?angled triangular SIW cavities

Herein, a rigorous derivation of an isosceles right-angled triangular (IRT) metallic cavity is analysed. Then, the transverse field components in IRT substrate-integrated waveguide (SIW) are derived, and expression resonant frequencies can also be obtained. novel perturbed SIW proposed, which based on characteristics modes capacitive-loading technique. Three prototypes were designed to verify validity analysis this study. First, dual-mode single passband filter was implemented using TE102 TE202. Next, two tri-mode triple-band bandpass filters (BPFs) TE101, TE202 synthesised, verified measured for demonstration, including second-order direct-coupled one operates at 8.02, 11.44 12.52 GHz, fourth-order 7.7, 11.0 12.1 GHZ. The curves agree well with simulated ones. Very compact circuit sizes excellent filtering performances have been achieved three prototypes.