Dual and tri-band bandpass filters based on novel Π-shaped resonator

A novel Π-shaped resonator is proposed, and compact dual-band and tri-band bandpass filters that meet IEEE 802.11 application requirements by using the new resonator are designed. The dual-band bandpass filter centres at 2.45 and 5.6 GHz with a simulated passband insertion loss of no more than 0.8 dB, and the tri-band bandpass filter which is got by two-path coupling achieves simulated passband insertion loss of no more than 1.1 dB. The new designs are demonstrated by experiment. The new filters have advantages of simple and compact structures, low passband insertion losses, good frequency selectivity and miniature circuit sizes. All these have prospect to be applied in future wireless communication systems.     

A Novel Crossed Resonator and Its Applications to Bandpass Filters

A novel open and short stubs loaded crossed resonator and its applications to cross-coupling filter and tri-band bandpass filters are presented in this paper. Based on the lossless transmission line model analysis, it is found that the first three resonance frequencies of the crossed resonator can be conveniently controlled. Benefiting from this feature, the resonator can be utilized to design not only a cascaded triplet (CT) filter, but also a tri-band bandpass filter. The tri-band filter offers two tunable passbands and one fixed passband. The first and third passband frequencies can be tuned effectively by changing the lengths of the stubs. To demonstrate these applications, a CT filter and two tri-band bandpass filters using a crossed resonator are implemented. The experiments verify the theoretical predictions and simulations.      

Design of Compact Tri-Band Bandpass Filters Using Assembled Resonators

A novel approach for designing tri-band bandpass filters with independently controllable center frequencies and improved stopband rejection characteristic is presented in this paper. The assembled resonator constructed by a stepped impedance resonator and a common half-wavelength resonator is employed to obtain tri-band response. The stepped impedance resonator is designed to operate at the first and third passbands and the other resonator is designed to operate at the second passband. Two kinds of filter configurations with cascaded and pseudointerdigital formats are proposed. Based on lossless lumped-element equivalent circuit, it is found that both filter structures can introduce transmission zeros between passbands. To verify the proposed approach, two filters are designed and fabricated, the measured results exhibit tri-band bandpass responses with high selectivity.     

基于枝节加载谐振器的新型三频带通滤波器设计

提出了一种新型平面三频带通滤波器,该滤波器由一个加载短路枝节的阶梯阻抗谐振器,一对加载开路枝节的背靠背E型谐振器,以及包含源负载直接耦合的馈电结构组成.所采用的枝节加载谐振器的多模工作特性使滤波器的体积大大减小,同时每个通带的位置及其耦合特性都能够独立调谐.另外,通过源负载直接耦合引入通带两侧的传输零点,实现了滤波器良好的频率选择性.最后设计并加工了一款高选择性小型化三频带通滤波器,其三个通带的中心频率分别为2.0GHz,3.95GHz和6.35GHz,插入损耗均小于2.5dB,带内回波损耗均优于14dB,实验结果与仿真结果吻合良好.     

60-GHz Band Dual-Mode Microstrip Ring Resonator Bandpass Filter Using Micromachining Technology

A new compact millimeter-wave dual-mode ring resonator bandpass filter is proposed. This filter has a 15% bandwidth at 58 GHz with 3.4 dB insertion loss. Input/output lines and ring resonator are directly connected to obtain tight coupling, and an open-end stub is inserted for dual-mode operation. This filter is fabricated on a GaAs wafer by using MEMS technology and can be applied for the millimeter- wave SoC.     

Tri-band microstrip bandpass filter using input/output cross coupling

A compact tri-band bandpass filter using input/output cross coupling is proposed. Three passbands can be adjusted by changing the characteristic impedance of the T-shaped structure with a shorted stub. The three passbands are designed to operate at 1.85, 3.5 and 5.2 GHz based on the T-shaped structure. Four transmission zeros are used to realise high selectivity for the passbands. Good agreement can be observed between the measured and simulated results.     

A wideband stepped-impedance rectangular-ring resonator bandpass filter with multiple notched bands

A configuration of wideband bandpass filter (BPF) with multiple notched bands is presented. Proposed BPF is based on stepped-impedance resonator. By utilising dual stepped-impedance resonators in folded topology a rectangular-ring resonator is formed. Two notched bands in the passband are achieved without using asymmetrical coupled lines. In other words, the filter configuration is capable of producing notched bands. It should be noted that additional information on filter performance and design is presented. Measurement results are presented to approve propounded filter characteristics. The measured passband of the second proposed filter is from 3.68 to 10.2 GHz with insertion loss of –1.76 dB in the first passband at the centre frequency of 4.45 GHz. The measured notched band frequencies are about 5.45 and 7.95 GHz with rejection of –21.77 and –20.82 dB, respectively. The return loss in the passband is better than –11.4 dB.     

Novel design of tri-band bandpass filter based on fractal-shaped geometry of a complementary single split ring resonator

A novel electrically small composite right/left-handed transmission line (CRLH TL) cell based on the Minkowski-shaped geometry of a complementary single split ring resonator is proposed and analysed by the S parameters extraction method. EM simulation results have confirmed the roughly tri-band response of the proposed CRLH TL cell attributed to the fractal multiband nature. A tri-band bandpass filter (BPF) centred at 1.1, 2 and 2.74?GHz with minimum insertion loss 0.4, 1.1 and 1.45?dB was synthesised and fabricated by employing an additional two Hilbert-shaped quarter-wave open-circuit stubs which provided transmission zeros located between passbands to obtain high selectivity. This simple design concept was verified by measurement as well as simulation results.     

Dual-band bandpass filter based on mixed electric and magnetic coupling of the hybrid quasi-lumped resonator

A novel compact dual-band bandpass filter based on mixed coupling of the hybrid quasi-lumped resonator is proposed. The filter is composed of two independent signal paths, each can generate one passband with two identical hybrid quasi-lumped resonators. The proposal combines the mixed electric and magnetic coupling technology with this novel resonator in the filter design. Analysis of the filter has been done with the equivalent circuit method. To validate the approach, a dual-band bandpass filter operating at 2.4/5.2 GHz has been fabricated. Both passbands were realised with mixed coupling. An additional transmission zero is generated at either passband. Final fabricated filter has good band skirt, low insertion loss and good out-of-band performance. Reasonable agreement is found between the calculated, simulated and measured results. The implementation area is 0.21λ_g × 0.12λ_g.     

Double-Layer Frequency Selective Surface for Terahertz Bandpass Filter

A thin, low-cost, double-layer frequency-selective surface (FSS) bandpass filter has been designed, fabricated, and measured for operation in the terahertz band. The present FSS structure is composed of double-layer tin foil with a hexagonal lattice array of circular holes. A flat passband is observed with a 3-dB bandwidth of 0.20 THz from 0.81 to 1.01 THz, which is about 22% relative to the center frequency. This bandpass filter based on double-layer FSS structures achieved average insertion loss of 0.7-dB and 106.31-dB/THz band-edge steepness. We have found good agreement between theoretical calculations and experimental results.     

Design of a New Tri-Band Microstrip BPF Using Combined Quarter-Wavelength SIRs

A new tri-band microstrip bandpass filter (BPF) is designed to produce three passbands at the commercially practical frequencies through a single piece of filter circuitry. The basic component used to build the proposed filter consists of two quarter-wavelength (lambda/4) stepped-impedance resonators (SIRs). One of the lambda/4 SIRs is designed to operate at 1.57 GHz and 5.25 GHz, and the other at 2.45 GHz. The feed positions for the two lambda/4 SIRs are carefully located to have the same distance from the via-hole ground and meanwhile to give the required external quality factors (Q_e's). In such a way, the microstripline sections between the via-hole and each of the feed positions can be combined into one to simplify the filter structure, and to reduce the BPF circuit size. Performance of the newly designed tri-band BPF is verified by measured results     

一种紧凑型微带三频滤波器的设计

提出了一种新型微带三频滤波器,滤波器由两个弯折并相互嵌套的分支线谐振器和一个T形谐振器组成。谐振器之间相互耦合,得到三通带频率响应特性。该滤波器可通过调节微带线几何参数改变通带位置以及带宽,以满足不同应用需求。这种结构的滤波器结构紧凑,电路面积小,三个通带两边各引入一个传输零点,增强了通带间的隔离度以及阻带抑制特性。设计并制作了一款1.57/3.55/5.2GHz三通带滤波器,测试结果与仿真结果基本相符,验证了该滤波器结构的有效性。     

Millimeter-wave Micromachined Filter Design by Artificial Neural Network Modeling Technique

This paper presents a design approach for a 34 GHz λ/2 resonator micormachined bandpass filter by using the artificial neural network (ANN) modeling technique. Three important dimensions of the filter layout are used to capture critical input-output relationships in the ANN model. Once fully developed, the ANN model has been shown to be as accurate as an EM simulator and much more efficient computationally in the design optimization of the filter.     

基于奇偶模分析法的四模谐振器结构的双通带带通滤波器设计

提出了一款基于四模谐振器的新型双通带带通滤波器.设计的四模谐振器基于微带线结构,由四个开路枝节和一个短路枝节组成.两次采用奇偶模分析法对该四模谐振器结构进行分析.该四模谐振器的每个模式能够实现独立调节,同时每两个模式形成一个通带.采用源与负载耦合的馈电方式,提高滤波器的带外抑制性.该滤波器具有四个传输零点和四个传输极点.测试结果表明,该双模双通带滤波器工作于2.08GHz和6.07GHz,3dB带宽分别为11.06%和7.74%.设计的滤波器具有紧凑的结构,只有0.28λ_g×0.11λ_g大小.     

一种具有陡峭边带的宽带带通滤波器设计

基于一种新型的多模谐振器设计了一款宽带带通滤波器,该多模谐振器由鱼骨形谐振器及中心加载倒T形谐振器构成。滤波器的中心频率位于2.47 GHz,相对带宽为100%。滤波器具有极高的频率选择性,其边带滚降速度分别为232 dB/GHz和168 dB/GHz。此外,滤波器还具有较低插入损耗0.4 dB,紧凑的电路尺寸以及宽阻带抑制能力。     

一种小型化带通滤波微带巴伦设计

提出一种小型化带通滤波微带巴伦的设计。在Marchand巴伦的基础上,使用一个半波长和两个1/4波长传输线作为谐振器,在带通滤波微带巴伦的两个输出端口可以获得相同幅度和相反相位的平衡信号。利用谐振器平行线耦合可以观察到通带两侧存在两个传输零点。对提出的中心工作频率在2.65 GHz的带通滤波微带巴伦进行了实物加工与测试。两个输出端口信号幅度差与相位差分别为±0.4 dB和180°±5°。仿真与测量结果有较好的一致性,验证了本文所提方案的可行性。     

一种新型超宽带带通滤波器的设计

介绍一种新型的超宽带带通滤波器,研究了微带阶梯阻抗谐振器的阻抗特性,利用该并联结构实现了超宽带带通滤波器的带外传输零点。设计了一款性能较好的宽带带通滤波器,实际测试结果与仿真结果十分吻合,证明了设计方法的正确性。     

一种新型开路环谐振带通滤波器

利用开路环终端的内部电容耦合效应,提出一种结构紧凑,具有小型化和良好的二阶和三阶谐波抑制能力的开路环谐振器窄带带通滤波器.分析了开路环终端电容内部耦合结构变化对带通滤波器谐波抑制特性的影响,并利用上述结构仿真和设计了一个中心频率为1.5 GHz的带通滤波器,模拟结果与实验结果吻合良好,验证了滤波器的设计思想.     

Design and analysis of a super compact wide-band bandpass filter based on metamaterial resonators

In this paper, a novel compact wide-band bandpass filter (BPF) with a wide frequency range is presented. This filter consisting of a multi-mode resonator (MMR) and four metamaterial unit-cells benefits from a very compact size. Unit-cells based on a complementary spiral resonator (CSR) including a metallic via, improve both upper and lower stopband rejection and compensate the insertion loss (I.L) within the passband altogether. This wide-band filter presents a 3-dB bandwidth of 7.7 GHz, ranging from 3 GHz to 10.7 GHz and the Insertion loss is less than 0.7 dB over the passband. The measured results are in good agreement with both the full-wave electromagnetic simulation and the proposed circuit model results. The dimension of the fabricated filter is 0.128 λ × 0.1 λ (i.e., 5.6 × 4.4 mm²). This filter is considerably compact compared to the other wide-band bandpass filters with the same substrate.     

Compact wideband bandpass filter using quad mode resonator

This paper presents a compact wideband bandpass filter for TETRA band applications. The proposed filter design is based on a quad mode resonator designed using small rectangular loop loaded with four Stepped Impedance Stubs (SISs) and a short circuit stub. The four modes of the resonator help in generating a wide passband. The use of SISs makes the filter compact. In addition to four transmission poles, the resonator inherently generates a transmission zero above the higher end of passband. Two transmission zeros are generated by the input/output coupling which helps in increasing the selectivity and also for achieving wide stopband. This filter provides a 3 dB fractional bandwidth of 30.33% and maximum insertion loss of 1.3 dB at the center frequency 0.36 GHz with a compact size of 0.125 λ_g × 0.085 λg (4.1 × 2.78 cm²).