Multiwideband Bandpass Filter Based on Folded Quad Cross-Stub Stepped Impedance Resonator

Abstract

A multiwideband bandpass filter (MW-BPF) using a quad cross-stub stepped impedance resonator (QC-SSIR) was simulated, fabricated, and measured. The proposed QC-SSIR is designed on a four-series arrangement of crossed open stub (COS) structures where each open stub is developed with a step impedance resonator (SIR) structure to generate a wide bandwidth. Compared to the COS resonator, the QC-SSIR has a wider fractional bandwidth and good transmission coefficients and is compact. ABCD matrix analysis is used to investigate the filter structure. Furthermore, the MW-BPF is designed on an FR4 microstrip substrate with εr = 4.4, thickness h = 1.6 mm, and tan δ = 0.0265. The results show that the proposed MW-BPF using a QC-SSIR achieves transmission coefficients/fractional bandwidths of −0.60 dB/49.3%, −1.49 dB/18.7%, and −1.93 dB/13.9% at 0.81 GHz, 1.71 GHz, and 2.58 GHz, respectively. Furthermore, to reduce the filter size, a folded QC-SSIR (FQC-SSIR) structure was also proposed. The results show that the proposed MW-BPF using an FQC-SSIR achieves transmission coefficients/fractional bandwidths of −0.57 dB/49.6%, −1.21 dB/17.7%, and −1.76 dB/12.5% at 0.82 GHz, 1.80 GHz, and 2.62 GHz, respectively. The size of the proposed MW-BPF using an FQC-SSIR is reduced by up to 46% compared with the MW-BPF using a QC-SSIR. Finally, the performance of the simulated MW-BPF based on the QC-SSIR and FQC-SSIR was in good agreement with the measurement results.

Design and Synthesis of Multi-Mode Bandpass Filter for Wireless Applications

“…In satellite communications, four-pole or six-pole double (dual) mode filters are commonly used in output multiplexers, and eight-pole double mode filters are commonly used in input multiplexers. Output multiplexers have at least two or three cascaded waveguide cavities, while input multiplexers have at least four cascaded waveguide cavities [23][24][25][26][27].…”

Four Subbands from Dual Mismatched Wideband Bandpass Filter for 5G/WAS/Wi-Fi/WiMAX/WLAN Applications

“…The stub-loaded resonators (SLRs) and the stepped-impedance resonators (SIRs) [22] are most commonly used in multiband filter designs [7]. The literature is rich enough in some techniques, such as SIR [23,24], stepped-impedance ring-loaded resonator (SIRLR) [21], stub loaded with uniform impedance resonators (UIR) [6], and substrate-integrated waveguide (SIW) [25,26]. Sometimes, the mix of techniques improves physical dimensions or electric performance [27].…”

Bandpass/bandstop switching with tunable pass band operation based on split ring and open loop resonators

“…Various studies are conducted to achieve the desired response of the filter with mandatory constraints in the design process such as compactness in size, sharpness in the roll-off rate, simplicity in design, and minimization in passband insertion losses [4][5][6][7][8]. There are many techniques to achieve either a band pass or band reject behaviour including the defected ground structure (DGS), stepped impedance resonator (SIR), open loop resonator (OLR), split ring resonator (SRR), and substrate integrated waveguide (SIW) [9][10][11][12][13][14][15][16][17].…”

“…Another model in [10] utilizes DGS for obtaining dual/triple band operations in addition to the stepped impedance open stub technique is used to minimize cross-coupling between microstrip line resonators and the DGS and to improve the selectivity of the passband, also DGS structure can be integrated with composite right/left-handed (CRLH) structure to achieve wide-band bandpass behaviour [11]. Stepped impedance resonators are considered one of the commonly used techniques to produce multiple passbands and it is succeeded to achieve dual pass bands in [12], also a multi-wideband bandpass filter is introduced in [13] utilizing quad cross-stub SIR technique to obtain wideband behaviour.However, the size of the filter model is too large and it is difficult to be embedded in modern wireless systems.The open-loop resonator (OLR) technique was utilized in [14] for dual-band operation (WLAN and WiMAX) with deep transmission zeros. To obtain THz wideband pass filter behavior, a complementary split ring resonator (CSRR) metamaterial was utilized [15], and the obtained results were sufficient enough to propose the BPF for the detection of peptides in the human body.…”