Realisation of new single‐layer triple‐mode substrate‐integrated waveguide and dual‐mode half‐mode substrate‐integrated waveguide filters using a circular shape perturbation

Abstract

A method of ‘mode shifting’ is presented for realisation of triple‐mode and dual‐mode filters, in which the resonant frequency of one mode is shifted near to the resonant frequency of another mode using a perturbation. To realise a triple‐mode filter, a single‐layer substrate‐integrated waveguide (SIW) square cavity is perturbed by introducing vias at the middle of the structure. This perturbation causes mode shifting of the dominant mode (TE101) near to the next modes (TE102 and TE201). Operation of this triple‐mode resonator is analysed and resonant frequencies of the perturbed cavity are obtained theoretically. A triple‐mode filter is realised using this resonator and the filter is modelled by a coupling matrix based on the global eigenmodes. Moreover, by using the mode shifting technique, a novel dual‐mode bandpass filter with half‐mode SIW (HMSIW) structure is presented. Both the triple‐mode SIW and dual‐mode HMSIW filters are fabricated on a single‐layer substrate using a printed circuit board process.

Dual‐mode bandpass substrate integrated waveguide filter with a complementary split ring resonator

“…Interested readers can refer to Ref. for the definition of both and . Based on the formulas presented in Ref.…”

“…However, the filter suffers from an unexpected parasitic passband near the desired one. To circumvent the problem, we propose a perturbation scheme to drill a metallic via‐hole near the center of the hypotenuse of the cavity, which can cause the parasitic passband keep away from desired frequency . Additionally, the bandpass width can be adjusted by the diameter and the position of the perturbation via‐hole.…”

A compact wideband filter designed on single one‐third equilateral triangular cavity

“…By using the technique in Ref. , the coupling matrix of the quadruple‐mode filter is presented below.…”

“…Generally speaking, a bandpass filters based on substrate integrated technology can be fulfilled by using single‐, dual‐ or triple‐mode resonators. Recently, several papers have studied the dual‐mode triple‐mode SIW filters . All of published structures in them are based on rectangular or circular substrate integrated waveguide (SIW) resonator.…”

Fourth‐order dual mode substrate integrated waveguide filter

“…Modeling and design of dual mode filters can be performed using equivalent lumped element circuit (coupling matrix) , equivalent distributed model , and equivalent circuit based on propagation . Realizing the dual mode operation is also performed using mode shifting technique and mode splitting technique . In the latter technique, a perturbation is introduced inside a cavity supporting two degenerate modes.…”