Design of compact triple‐mode bandpass filter using double center stubs‐loaded resonator

Abstract

A compact microstrip triple-mode bandpass filter using half-wavelength (k/2) open-ended microstrip line with double center loaded stubs is proposed in this article. By introducing a radial-line stub to the traditional dual-mode resonator, a triple-mode resonator is realized and the mode characteristics of the resonator are discussed. Also, an equivalent lumped circuit is proposed and the method of parameters extracting is given. The proposed filter exhibits a quasielliptic function response with a compact circuit dimension. At last, an experimental filter is fabricated and a good agreement between simulations and measurements is reached.

High Selectivity and Wide-Stopband Quintuple-Mode Bandpass Filter with Multiple Transmission Zeros

“…In Deng et al (2011) andZhang et al (2010), tri-mode stub-loaded resonators were proposed and applied to make up a three-pole BPF on a single resonator that had high selectivity and wide upper stopband. A BPF with a combination of two centrally loaded λ/4-type stepped-impedance resonators (SIRs) and input/output sourceload coupling was achieved.…”

“…In recent years, planar microstrip bandpass filters (BPFs) using multi-mode resonators have been a hot research topic because of their compact size, high selectivity, low in-band insertion loss, and high out-of-band rejection, which skirts requirements for wireless communication systems (Hong et al, 2007;Deng et al, 2011;Zhang et al, 2010;Zhou et al, 2012;Lok et al, 2008;Wei et al, 2011;Fan et al, 2012). For example, a two-pole BPF based on a single dual-mode stub-loaded resonator was presented in Hong et al (2007), which saved space for a resonator for compact size and which could create a transmission zero (TZ) at a lower or higher stopband for good selectivity.…”

Microstrip Tri-Mode Bandpass Filters Using Modified Ring Resonators

“…Recently, microstrip tri-mode/multi-mode bandpass filters (BPFs) have been extremely attractive due to their advantages of the compact overall sizes and high performance [10][11][12][13][14][15][16][17]. By etching two pairs of rectangular slots on a circular patch resonator to split a pair of fundamental degenerate modes and perturb a third mode, a tri-mode bandpass filter was proposed in [13].…”

“…In addition, the trimode resonator could be also developed from the loop dual-mode resonator [14,15], where the new created resonant mode was declined to approach the first two inherent degenerate modes by introducing appropriate perturbation. In [16,17], the tri-mode resonators were realized by adding a radial-line stub or stepped-impedance line based on a conventional dual-mode stub-loaded resonator.…”

A novel Ku-band bandpass filter using triple-mode resonator

“…To improve selectivity and suppression out of band harmonic response, a novel unit structure is proposed and studied, where the transmission zero is applied to both lower and upper stopband. In order to increase stopband performance, a broadside-coupled hairpin structure is used to realize an ultra-wideband stopband filter [4][5][6].…”