Compact microstrip dual-band bandpass filter using short-stub loaded half-wavelength resonator

Novel compact microstrip dual‐mode multistub‐loaded stepped‐impedance resonator and application to communication systems

“…As a key circuit block in dual-band wireless communication systems, several design methods have been reported for the dualband bandpass filter (DBPF) [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. By cascade connection of bandpass and bandstop filters [1] (they occupy larger size relatively), by utilizing two step-impedance resonators (SIRs) [2] (the resonance frequencies of SIRs are dependent), by interleaving heterogeneous SIRs [3] (two types of SIRs were designed to have different fundamental resonance frequencies), with two-path coupling using isosceles right-angled triangular (IRT) resonator [4], with the assistance of fractal perturbation on IRT resonator for compact size achievement [4,5] (dual-band implementation is due to the application of the resonant modes), using defected stepped impedance resonator (DSIR) for miniaturization aims (DSIR has opposite impedance characteristic as the SIR) [6], using quarter wavelength SIRs [7,8], with intercoupled resonator having embedded stubs [9] (consists of a U-shaped nearly half wavelength resonator with an open-ended line), with both meanderloop resonator and CSRR defected ground slot (DGS) [10], DBPFs were proposed.…”

Tri-band bandpass filter using dual-mode resonators

“…The tri-band BPFs can be constructed using tri-section stepped-impedance resonators (SIRs), such as the ones in [1][2][3], although these structures are relatively complicated due to resonant frequencies of SIR are dependent, the three passbands at any desired frequencies can be obtained. Another widely used method to design tri-band filters is the stub loaded resonator (SLR) [4][5][6][7]. The three desired frequencies can be conveniently controlled by tuning the lengths of half-wavelength resonator, open/short-stub [4] and [5], open-Ioaded/half-wavelength resonator [6], open-Ioaded/quarter-wavelength resonator [7].…”

“…Another widely used method to design tri-band filters is the stub loaded resonator (SLR) [4][5][6][7]. The three desired frequencies can be conveniently controlled by tuning the lengths of half-wavelength resonator, open/short-stub [4] and [5], open-Ioaded/half-wavelength resonator [6], open-Ioaded/quarter-wavelength resonator [7]. Recently, a novel class of compact dual-mode triple-band BPFs based on a single microstrip ring resonator has been presented [8], the square ring loaded resonator (SRLR) [9].…”

An Approach for Multi-Band Bandpass Filter Design Based on Asymmetric Half-Wavelength Resonators

“…There are many methods to design multi-band filters, such as combining two single-band filters at different passband frequencies [1][2][3][4][5], adding defected stepped impedance resonator (DSIR) and microstrip stepped impedance resonator (MSIR) [6][7][8][9] or adding a couple of resonators [10][11][12][13]. The method of adding shunt open stub to the center of the resonator is used to design dual-band filter and there are three transmission zeros for the two passbands [14,15]. The combination of adding shunt open stub to the center of the resonator and adding resonators is used to design tri-band filter, where five transmission zeros for the three passbands [16][17][18].…”