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

Gunawan Wibisono,Toto Supriyanto,Febrizal Ujang,Teguh Firmansyah,Herudin Herudin,Mudrik Alaydrus,Muh Wildan

doi:10.1155/2020/4124721

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.

Highlights

In recent years, a multiband transceiver has been required to improve efficiency and support the development of various types of wireless communication standards [1,2,3]
Some attractive methods frequently used for the multiband bandpass filter (MB-BPF) design include quarter-wavelength step impedance resonators (SIRs) [8], trisection SIRs [9,10,11,12], cascaded multiband resonators [13], loaded crossed resonators [14], stub-loaded resonators (SLRs) [15], trimode SLRs [16], stub-loaded quarter-wavelength resonators [17], stub-loaded and defected ground resonators (DGSs) [18, 19], and crossed open stubs (COSs) [20,21,22]. e most challenging part of an MB-BPF design is to allow several passbands simultaneously without sacrificing any design freedom or additional drawbacks such as complex geometry and International Journal of Antennas and Propagation increasing size
The MWBPF using an FQC-SSIR has a size of 97 mm × 129 mm

Summary

Introduction

A multiband transceiver has been required to improve efficiency and support the development of various types of wireless communication standards [1,2,3]. E results show a good electrical performance; the additional passbands would make the size of the BPF greater and the bandwidth narrower. E performance of an MB-BPF using a COS is proposed and evaluated in [21, 22], but these studies only resulted in a BPF with a narrow bandwidth. E proposed filter utilizes two coupled stub-loaded dual-mode resonators (SLDMRs) instead of three sets of resonators to achieve a compact triband BPF with good transmission coefficient and high selectivity [27]. Compact multiband BPFs with a wide bandwidth and good transmission coefficient, a quad crossstub stepped impedance resonator (QC-SSIR) was proposed. The proposed multiband BPF exhibits a wide bandwidth, as shown, and a compact size.

50 Ω Port 2

B D cos θ0 j sin θ0

Implementation of an MW-BPF Using a QCSSIR and FQC-SSIR

Findings

Method