Tri-band Microstrip Bandpass Filter Using Dual-Mode Stepped-Impedance Resonator

Abstract

This letter presents a compact dual-mode tri-band bandpass filter by using a short-circuited stub-loaded stepped-impedance resonator (SIR) and a short-circuited stub-loaded uniform impedance resonator. Also, a hairpin SIR geometry is introduced to miniature the size of this filter while maintaining excellent performance. The use of a short-circuited stub at the central point of the hairpin SIR can generate two resonant modes in two passbands. Its equivalent circuit structure is analyzed by using the even-odd mode theory. For demonstration purposes, a tri-band filter for the applications of the Global Positioning System at 1.57 GHz, Worldwide Interoperability for Microwave Access at 3.5 GHz, and wireless local area networks at 5.2 GHz is designed, fabricated, and measured.

A novel compact triband bandpass filter using SIR embedded quarter-wavelength resonators

“…In recent years, modern multiband multiservice wireless communication systems have been developed rapidly. As one of the essential components, multiband bandpass filters (BPFs) have drawn much attention, and various design methods have been proposed . In , a compact second‐order triband BPF is designed based on Hilbert–Fork resonators.…”

“…In , a compact second‐order triband BPF is designed based on Hilbert–Fork resonators. In , stub loaded resonators are used to design triband filters which resonant frequencies can be tuned by the centrally loaded stubs. Second‐ and fourth‐order triband BPFs with tunable resonant frequencies achieved by square ring loaded resonators are presented in .…”

Design of a Compact and High Selectivity Tri-Band Bandpass Filter Using Asymmetric Stepped-Impedance Resonators (Sirs)

“…The fundamental resonant frequency of the proposed asymmetric SIR can be obtained by Equation (6) [6]:…”

“…Thus, as one of the key components in wireless communication systems, multi-band planar bandpass filters (BPFs) have gained much attention. Great efforts have been made to design multi-band BPFs, and various designs have been reported [1][2][3][4][5][6][7][8][9]. Half-wavelength [1] and quarter-wavelength [2] SIRs have been utilized to design quad-band or tri-band BPFs, whereas tri-section SIRs are used to design tri-band filters [3,4].…”

“…However, the design procedure is comparatively complicated. In [5] and [6], the combination of stub-loaded resonators (SLRs) and half-wavelength SIR is introduced. Recently, the design method to achieve high performance multi-band BPFs using multimode resonators (MMRs) has attracted much attention [7][8][9].…”