基于枝节加载多模谐振器的电调微波滤波器设计

针对认知无线电技术对射频微波滤波器的新要求,提出了一种基于枝节加载多模谐振器的电调微波滤波器。该电调微波滤波器由一个枝节加载微带多模谐振器和变容二极管组成,实现了滤波器的小型化。在分析枝节加载微带多模谐振器的基础上,通过在微带谐振器两端和加载枝节上加载变容二极管的方法,设计了枝节加载的电调多模微带谐振器,并提出了复杂微带谐振器谐振特性的分析方法。采用源和负载耦合的方法在通带右边引入一传输零点。通过在源和负载端放置耦合线的方法,提高了滤波器的通带选择性。针对滤波器带外衰减小的问题,引入一种新型的频变馈电结构,改善了滤波器的带外衰减特性。通过优化仿真确定了电调滤波器的尺寸参数。仿真验证了该滤波器的特性,当变容二极管的可调范围为2pf-10pf时,滤波器的频率可调范围为2.10GHz-2.40GHz,频率变化范围为300MHz。     

工艺误差对盘式耦合谐振滤波器的影响

MEMS谐振器采用阵列耦合设计可以降低运动电阻、提高功率处理能力等,但是阵列耦合谐振器的性能对于耦合梁结构特性非常敏感,据此分析工艺误差造成的耦合梁形状变化对圆盘阵列耦合谐振器滤波性能的影响.对耦合梁不同程度倾斜下的谐振滤波器结构和性能参数进行理论分析,并采用有限元仿真软件ANSYS进行模拟仿真.结果表明当耦合梁分别发生0.1°、0.2°、0.5°倾斜时,滤波器中心频率分别下偏10×10-6、24×10-6、51×10-6.当倾斜角达到0.5°时,分数带宽偏差将达到5.6%.提出了一种半高耦合梁的圆盘阵列谐振滤波器,其滤波器性能稳定性要4×优于常规型圆盘耦合谐振滤波器.     

基于非对称耦合阶跃阻抗谐振器的高阶窄带超导平衡式滤波器设计

本文研究了 一款基于非对称耦合阶跃阻抗谐振器SIR(stepped-impedance resonator)设计的6阶窄带超导平衡式带通滤波器,该滤波器具有高的频率选择性以及宽阻带特性.本文首先研究了3种具有不同耦合特性的SIR耦合对,分析了其差模DM(differential mode)相位移、耦合系数,以及共模CM...     

一种新的介质滤波器设计方法

分析并设计了新型介质滤波器结构,提高了滤波器的性能,减小了体积.同时使用HFSS电磁仿真软件对所设计的谐振器进行仿真.同时设计了新型的滤波器耦合矩阵综合和优化方法,大大提高了耦合矩阵综合与优化的性能和计算速度.     

基片集成波导滤波器的设计

从设计指标出发,采用基片集成波导结构,研究并设计了一种小型化的滤波器。通过采用四分之一基片集成波导谐振器,实现了整体电路的小型化。通过引入微带谐振器,在频带高端引入一个传输零点,提高了滤波器的选择性。滤波器的中心频率设置在3.6GHz,通带的带宽为400MHz。     

Ka波段硅基MEMS滤波器

滤波器是微波毫米波电路中的一个重要部件,本文介绍了采用基片集成波导技术和ICP深刻蚀微机械通孔阵列的硅基MEMS滤波器.设计制作了MEMS滤波器的核心部件谐振器,测试结果显示该谐振器无载Q值大于180,频率误差控制在2%以内.以此为基础采用理论计算与实验设计相结合的方法设计了一个Ka波段硅基MEMS滤波器.滤波器中心频率为30.3 GHz,插入损耗1.5 dB,相对带宽5%.芯片尺寸为10.0 mm×2.8 mm×0.4 mm.     

基于CRLH—TL及CSRR的带通滤波器

首次提出一种复合左右手传输线零阶谐振器及互补谐振环的新型带通滤波器.设计方法利用左右手复合传输线的独有特性,即零阶谐振器中心频率与谐振器长度无关,能在特定非零频率上得到无限波长的特点,来构造环形滤波器,并且地板蚀刻了长方形互补谐振环结构.设计过程中使用了AnsoftHFSS软件进行全波仿真,经过多次仿真,通过调节参数大小优化设计,最终结果得到中心频率为1.85GHz、带宽为0.1GHz的新型带通滤波器.在达到同样效果的前提下,减小尺寸,单个谐振器与传统相比体积减少了近80%,长方形CSBR还提高了传输特性.上述结构的实现对于左手材料在微波器件中的发展有一定的促进作用,进一步扩大了左手材料的应用范围.     

基于复合左右手传输线的带通滤波器小型化设计

提出了一种工作于X波段的基于复合左右手传输线理论的零阶谐振器单元.利用两个这样的零阶谐振器单元设计出一种工作于9.2 GHz～9.5 GHz的新型带通滤波器,对设计进行全波的仿真,并且将全波仿真结果和实验测量结果进行了对比.运用基于S参数的提取方法对该滤波器性能进行了理论分析.结果表明,该滤波器与基于耦合微带线形式的传...     

基于两种谐振器的微型化毫米波LTCC滤波器设计

利用两种新型谐振器设计多层毫米波低温共烧陶瓷(LTCC)滤波器,其一是双环谐振器,另一是分形缺陷梯形谐振器.使用这两种谐振器设计的LTCC滤波器都采用带线结构,整个体积为5.5 inm×2.5mm x0.6mm,利用全波分析软件优化设计并加工出两种结构的滤波器,双环谐振结构滤波器的中心频率为31.5GHz,相对带宽为10.0%,带内插入损耗和回波损耗分别为1.2,11.4dB.分形梯形谐振腔滤波器具有较宽的频带,带宽为30.1-39.20GHz,相对带宽为26.3%.带内插入损耗小于1.9dB,回波损耗小于11.2dB.测试结果与仿真分析数据基本一致,说明方案可行有效,所设计滤波器可以满足毫米波通讯系统的要求.     

基于T型谐振器的窄带带通滤波器设计

基于T型谐振器结构设计了一款中心频率为2.81GHz的窄带带通滤波器。该T型谐振器横向为开路传输线,纵向为短路传输线,应用奇偶模分析法对其进行理论分析,判断出T型谐振器的谐振模式。通过对T型谐振器进行弯折处理,不仅有效缩减了滤波器的整体尺寸,而且改变了其谐振模式,利于滤波器的窄带特性。为有效增强滤波器的耦合度,输入/输出馈线与谐振器之间采用零度馈电方式,成功引入了通带两侧的两个传输零点,有效提升了滤波器的选频特性及阻带抑制能力。     

Electromagnetic design of folded‐waveguide resonator filter with single finite‐frequency transmission zero

This article presents electromagnetic (EM) design of a new folded‐waveguide resonator filter that uses an advanced coupling scheme to achieve the desired asymmetric frequency response with an attenuation pole of finite frequency on the high side of the passband. A filter of this type with a fraction bandwidth about 5% at a center frequency of 4.45 GHz has been successfully designed using a commercially available electromagnetic simulator. The designed filter has been fabricated and tested. Simulations and experimental results are presented to validate the design and to show the advantages of this type of filter. This filter also provides a compact size compared with conventional cavity resonator filters. © 2007 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008.     

A novel dual‐band bandpass filter using co‐directional split ring resonators with closely spaced passbands and wide upper stopband

In this article, interdigital capacitor loaded co‐directional split ring resonators (CDSRRs) and their dual‐band bandpass filter applications are proposed. The proposed resonator is formed by nested open loop resonators having open ends at the same place unlike conventional split ring resonators (SRRs). In addition, the inner open loop resonator has interdigital capacitor located between the open ends. The proposed resonator exhibits dual resonance behavior with a small center frequency ratio. Both of resonance frequencies can be controlled due to the changes in the interdigital capacitor and the electrical length of the outer resonator. A dual‐band microstrip bandpass filter is designed by using the proposed CDSRR. Two CDSRRs are used to obtain two poles in each passband. Overall electrical length of the designed filter is 0.23 λ_g × 0.14 λ_g (0.0329 λ_g²), where λ_g is the guided wavelength for the used substrate at the lowest passband center frequency of 1.8 GHz. A small center frequency is obtained by adjusting the second passband at 2.27 GHz. A very wide upper stopband, closely spaced passbands, low insertion losses and high selectivity at both passbands can be obtained by means of the proposed structure. The designed filter was also fabricated and tested. The measured results show a very good agreement with the predicted results.     

A widely tunable bandpass filter adopting novel fully tunable resonators

A widely tunable bandpass filter adopting a novel fully tunable resonator is proposed in this letter. The fully tunable resonator is mainly consisted of an open ring, a frequency tuning structure, and a coupling tuning structure. Adopting the fully resonators, the center frequency, the input/output external Q value, and the coupling coefficients can be tuned at the same time. And the tuning range of a tunable filter adopting the novel fully tunable resonators can be expanded. The fully tunable resonators can be combined to achieve more excellent suppression performance. A widely tunable bandpass filter consisted of five fully tunable resonators with 86.5% frequency tuning range is designed, fabricated, and measured. The simulated results are in good agreement with the measured ones.     

A flexible liquid‐metal alloy bandpass filter

This article presents a liquid‐metal Galinstan alloy bandpass filter (BPF) with good flexibility, which is fabricated by an improved soft lithography process. The Galinstan alloy is enclosed in the microfluidic channels of elastomeric polydimethylsiloxane (PDMS) substrates. Together with the PDMS substrates, the Galinstan alloy based filter features bending, twisting and stretching capabilities along any direction. A second‐order open‐loop resonator filter with 2.4 GHz center frequency and 15% fractional bandwidth was designed and fabricated to verify this concept. Experiments show that frequency response of the filter is almost unaffected in the case of bending of the different radii or twisting, while its center frequency slightly shifts down in the stretching condition. The proposed filter can be used for the flexible and conformal electronics.     

A bandpass filter using asymmetric stepped‐impedance resonators and symmetric T‐shape interdigital capacitor structures with wide out‐of‐band rejection

In this study, a novel stepped impedance resonator (SIR) is proposed. This SIR is composed of two stepped impedance transmission‐lines and an interdigital capacitor structure. The proposed resonator has a high ratio of the first spurious frequency f_s to the fundamental frequency f₀ and is suitable to design wide stopband filters. An equivalent model is used to analyze the resonant properties of the resonator. The design guidelines of the proposed resonator are summarized. Moreover, the coupling properties of the resonator are simulated and analyzed. Finally, a small high‐temperature superconducting bandpass filter is designed and fabricated using the proposed SIRs. The stopband of the filter is extended up to 4.0 f₀ and 3.5 f₀ with 30 and 60 dB out‐of‐band rejection levels, respectively.     

Capacitive Coupled Wide-Notch Stepped Impedance Narrow-Band Bandpass Filter for WiMax Application

The development of wireless communication standards necessitates optimal filter design for the selection of appropriate bands of frequencies. In this work, a compact in size pair of parallel coupled symmetric stepped impedance-based resonator is designed with supporting to the WiMAX communication standards. The coupled resonator is tuned to allow the frequency band between 3.4 GHz and 3.8 GHz, which is centered at 3.6 GHz. A parasitic effect of capacitively coupled feed structure is used for exciting the two symmetrical stepped impedance resonators. The bandwidth and selectivity of the filter are enhanced with the change of characteristic impedances and controlling the coupling gap between resonators. This design offers single narrow sharp passband selectivity as well as multiple stopband harmonic suppression arising as a result of multiple transmission zeros. The designed filter operates with a fractional bandwidth (FBW) of 11.47%. The proposed single narrowband bandpass filter provides better suppression in either side of the tuned frequency (3.6 GHz) without degrading the passband performance. Also, this novel filter offers an insertion loss of about −0.08 dB and a return loss of greater than −30 dB in passband. This approach is useful for eliminating unwanted spurious harmonics responses that enter the desired response. The suggested bandpass filter has been simulated using Advanced Design System (ADS) tool, and the measurement has been made using a network analyzer, and the results are reported.     

Analysis and optimization of the unpredictable transmission zero in X‐band filter design

This article focuses on the common problem of uncontrollable transmission zero (TZ) in X‐band filter design. Using uniform impedance rectangular resonator (UIRR) to design an X‐band filter always results in an unpredictable TZ on the low‐frequency side of the passband, which greatly deteriorates the frequency selectivity of the filter performance. Electromagnetic coupling polarity analysis of the UIRR shows that the magnetic crosscoupling between nonadjacent resonators which is opposite to the main coupling plays a major role in the unpredictable TZ. By optimizing the UIRR from the loop structure with a small opening to the folded one, weak couplings between resonators are obtained. A high‐temperature superconducting filter at X‐band using folded UIRR resonator was designed and fabricated with a center frequency of 10.01 GHz and a bandwidth of 58 MHz, and the uncontrollable TZ has been removed successfully from the low‐frequency side of passband. The measured insertion loss is less than 0.4 dB and the return loss is greater than 15 dB.     

一种微带双模带通滤波器的设计

提出一种新型的双模微带贴片带通滤波器,利用方形微带谐振器的简并主模来实现双模结构。通过一定的微扰和馈电方式来激励起这对简并模并使之相互耦合以实现通带。研究表明利用这种结构设计滤波器,与传统的设计相比其尺寸会减小。这种滤波器结构紧凑简单且有很好的性能,被广泛应用于微波射频电路。     

Design of wideband bandpass filter using short‐circuited circular patch resonator loaded with slots

This paper presents a wideband bandpass filter design based on a short‐circuited circular patch resonator with inductively loaded slots. The cavity model method is used to analyze the excited resonances of the resonator. According to the illustration of the cavity model, the TM₀₁₀ mode is excited as the fundamental mode, the resonant frequency of which is much lower than that of the TM₁₁₀ mode and can be further lowered by the loaded arc‐oriented slots. Therefore, the proposed resonator can be used to design a filter with compact size. In addition, one of the two orthogonal degenerate TM₁₁₀ modes can be independently tuned by the slot along the symmetric plane without affecting the TM₀₁₀ mode. Since the resonant frequency of each mode can be tuned independently by the parameters of the slots, and the coupling between resonant modes of the resonator and source/load can be adjusted by the feeding angle and the capacitive loaded stubs on the feeding lines, the center frequencies and bandwidths of the designed bandpass filters can be tuned easily. The analysis is theoretically and experimentally verified by two examples with good agreement between the simulated and measured results.