A bandpass filter with cross-coupled L-shape folded resonators for compact size and spurious suppression

Author(s):  
Prayoot Akkaraekthalin ◽  
Suthat Hongdamnuen ◽  
Vech Vivek
Circuit World ◽  
2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Sandhya Ramalingam ◽  
Umma Habiba Hyder Ali ◽  
Sharmeela Chenniappan

Purpose This paper aims to design a dual mode X-band substrate integrated waveguide (SIW) bandpass filter in the conventional SIW structure. A pair of back-to-back square and split ring resonator is introduced in the single-layer SIW bandpass filter. The various coupling configurations of SIW bandpass filter using split square ring slot resonator is designed to obtain dual resonant mode in the passband. It is shown that the measured results agree with the simulated results to meet compact size, lower the transmission coefficient, better reflection coefficient, sharp sideband rejection and minimal group delay. Design/methodology/approach A spurious suppression of wideband response is suppressed using an open stub in the transmission line. The width and length of the stub are tuned to suppress the wideband spurs in the stopband. The measured 3 dB bandwidth is from 8.76 to 14.24 GHz with a fractional bandwidth of 48.04% at a center frequency of 11.63 GHz, 12.59 GHz. The structure is analyzed using the equivalent circuit model, and the simulated analysis is based on an advanced design system software. Findings This paper discusses the characteristics of resonator below the waveguide cut-off frequency with their working principles and applications. Considering the difficulties in combining the resonators with a metallic waveguide, a new guided wave structure – the SIW is designed, which is synthesized on a planar substrate with linear periodic arrays of metallized via based on the printed circuit board. Originality/value This study has investigated the wave propagation problem of the SIW loaded by square ring slot-loaded resonator. The electric dipole nature of the resonator has been used to achieve a forward passband in a waveguide environment. The proposed filters have numerous advantages such as high-quality factor, low insertion loss, easy to integrate with the other planar circuits and, most importantly, compact size.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Karthie S. ◽  
Zuvairiya Parveen J. ◽  
Yogeshwari D. ◽  
Venkadeshwari E.

Purpose The purpose of this paper is to present the design of a compact microstrip bandpass filter (BPF) in dual-mode configuration loaded with cross-loop and square ring slots on a square patch resonator for C-band applications. Design/methodology/approach In the proposed design, the dual-mode response for the filter is realized with two transmission zeros (TZs) by the insertion of a perturbation element at the diagonal corner of the square patch resonator with orthogonal feed lines. Such TZs at the edges of the passband result in better selectivity for the proposed BPF. Moreover, the cross-loop and square ring slots are etched on a square patch resonator to obtain a miniaturized BPF. Findings The proposed dual-mode microstrip filter fabricated in RT/duroid 6010 substrate using PCB technology has a measured minimum insertion loss of 1.8 dB and return loss better than 24.5 dB with a fractional bandwidth (FBW) of 6.9%. A compact size of 7.35 × 7.35 mm2 is achieved for the slotted patch resonator-based dual-mode BPF at the center frequency of 4.76 GHz. As compared with the conventional square patch resonator, a size reduction of 61% is achieved with the proposed slotted design. The feasibility of the filter design is confirmed by the good agreement between the measured and simulated responses. The performance of the proposed filter structure is compared with other dual-mode filter works. Originality/value In the proposed work, a compact dual-mode BPF is reported with slotted structures. The conventional square patch resonator is deployed with cross-loop and square ring slots to design a dual-mode filter with a square perturbation element at its diagonal corner. The proposed filter exhibits compact size and favorable performance compared to other dual-mode filter works reported in literature. The aforementioned design of the dual-mode BPF at 4.76 GHz is suitable for applications in the lower part of the C-band.


Frequenz ◽  
2018 ◽  
Vol 72 (11-12) ◽  
pp. 533-537 ◽  
Author(s):  
Jin Xu ◽  
Qi-Hang Cai ◽  
Zhi-Yu Chen

Abstract This paper proposes a wideband bandpass filter (BPF) integrated single-pole double-throw (SPDT) switch by using the capacitively coupled LC resonators with loaded p-i-n diodes. The BPF-integrated on-state channel can be synthesized by using the coupled resonator filter theory, and the off-state channel with high suppression is built due to the misaligned resonant frequencies of LC resonators. As an example, a BPF-integrated SPDT switch is designed and fabricated with the central frequency of 1 GHz and the 3 dB fractional bandwidth of 29.7 %. The on-state channel has a measured insertion loss of 1.23 dB, and a 20 dB rejection wide stopband from 1.47 GHz to 8.6 GHz. The off state channel has a 43 dB suppression around 1 GHz. The isolation between two ports is better than 52.4 dB. The fabricated BPF-integrated SPDT switch size including bias circuits but excluding feeding lines has a compact size of 0.086 λg×0.096 λg.


Frequenz ◽  
2018 ◽  
Vol 72 (9-10) ◽  
pp. 455-458 ◽  
Author(s):  
Vivek Singh ◽  
Vinay Kumar Killamsetty ◽  
Biswajeet Mukherjee

Abstract In this letter, a miniaturized Band Pass Filter (BPF) with wide stopband centered at 0.350 GHz for TETRA band applications is proposed using a Spiral Short Circuit quarter wavelength Stepped Impedance Resonator (SSC-SIR) and a stub loaded on feed line for enhancement of rejection level in the stopband. Spiral configuration of the resonator is used for the miniaturization of BPF. The proposed BPF provides a 3dB fractional bandwidth of 13.7 % with two transmission zeros in the lower and upper stopband to provide good selectivity and four transmission zeros which provide wide stopband upto 6.86f0. Proposed BPF has a very compact size of 0.064λg×0.062λg.


2021 ◽  
Vol 36 (7) ◽  
pp. 865-871
Author(s):  
Jin Shi ◽  
Jiancheng Dong ◽  
Kai Xu ◽  
Lingyan Zhang

A novel miniaturized wideband bandpass filter (BPF) using capacitor-loaded microstrip coupled line is proposed. The capacitors are loaded in parallel and series to the coupled line, which makes the filter just require one one-eighth wavelength coupled line and achieve filtering response with multiple transmission poles (TPs) and transmission zeros (TZs). Compared with the state-of-the-art microstrip wideband BPFs, the proposed filter has the advantages of compact size and simple structure. A prototype centered at 1.47 GHz with the 3-dB fractional bandwidth of 86.5% is demonstrated, which exhibits the compact size of 0.003λ2 g (λg is the guided wavelength at the center frequency) and the minimum insertion loss of 0.37 dB.


Electronics ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 440 ◽  
Author(s):  
Huang ◽  
Yuan

A novel method to design a wideband substrate integrated waveguide (SIW) bandpass filter (BPF) with compact size, wide stopband and high selectivity is presented. In this method some unique electromagnetic band-gap (EBG) cells are periodically etched on the top layer of SIW to realize a wide passband propagating below the equivalent waveguide cutoff frequency. By changing the configuration of EBG cells, undesired harmonics in upper stopband can be suppressed and a wideband BPF with wide stopband can be obtained. By symmetrically loading two complementary split ring resonators (CSRRs) on the tapered gradient lines of the input/output ports, a transmission zero near the passband can be introduced, and it makes the frequency selectivity of upper sideband improve significantly. As a verification, a wideband SIW BPF with a 3.02 GHz absolute bandwidth (ABW) and a 64.7% fractional bandwidth (FBW) centered at 4.67 GHz is designed, simulated, manufactured, and measured. The results of the experiment and simulation are in good agreement.


Frequenz ◽  
2014 ◽  
Vol 69 (1-2) ◽  
pp. 65-70
Author(s):  
Jianzhong Chen ◽  
Xuefeng Li ◽  
Hongyu Shi ◽  
Anxue Zhang

Abstract A new design approach for a stepped impedance resonator (SIR) dual-band bandpass filter (BPF) with high multi-spurious suppression is proposed in this paper. The external coupling property of an SIR at multi-order resonant frequencies is fully studied. Different input impedances at desired frequencies are achieved by optimizing the unequal impedance transformer. The new solution shows the freedom in the choice of tapping point. The external quality values of multi-order harmonics vary with the shift of the tapping position. Wide upper stop-band rejection is realized by mismatching Qe at the unwanted harmonic frequencies, while keeping the Qe suitable for operating dual band to obtain good in-band performance. A traditional dual-band BPF and a novel practical BPF operated at 2.45/5.25 GHz are designed and fabricated to demonstrate the above idea. Good simulated and measured results are presented.


Sign in / Sign up

Export Citation Format

Share Document