CAD applying the finite-element method for dielectric-resonatorfilters

The progress of numerical techniques now permit us to analyze rigorously complex devices such as dual-mode cavity multipole filters or planar passive elements for coplanar monolithic microwave integrated circuits (MMICs). In this paper, we describe a rigorous design of dielectric resonator (DR) filters applying the finite-element method (FEM). We first present a dual mode coupling technique which replaces classical DRs, coupling, and tuning screws, which are commonly used in dual-mode filters, by slotted DRs. Next, a new theoretical analysis based on the contribution to the dual-mode filter response of the first DR hybrid mode and of higher order modes is described. This analysis can be applied to any type of microwave dual-mode filter. It allows us to define a procedure which explains the presence and controls the position of the two transmission zeros in the filter responses. In this paper, this procedure has been applied to improve filtering performances of a dual-mode DR filter. Finally, a synthesis method is developed to rigorously design for the first time, a four- and an eight-pole slotted DR elliptic filters. The experimental results were obtained with no tuning and the theoretical ones show good agreement     

脊双模波导滤波器的分析及设计

介绍了一种能实现脊双模波导滤波器的新型结构,分析了其腔内模式的耦合极性,利用不同的耦合极性对频率响应的影响可实现具有一对传输零点的双模滤波器,也可实现无传输零点的双模滤波器.以相同脊谐振单元不同的放置方向组成的两种带通滤波器为例,利用AnsoftHFSS仿真得到了两种不同的频率响应,结果与理论分析一致.最后设计出了一个六阶三传输零点的双通带滤波器,带内插损均小于0.6 dB,回波损耗小于-15 dB.     

Computer-Aided Filter Alignment and Diagnosis

The cavity resonant frequencies and coupling values of a wide range of bandpass filters, band-reject filters, and equalizers have been determined in situ by computer-adjusting analytic models to fit the scattering parameters measured on an automatic network analyzer. A higher order mode elliptic filter, a dual-mode quasi-elliptic filter, and a dual-mode band-reject filter are presented as examples. The general relationships between mechanical dimensions and circuit parameters are discussed. The circuit adjustment procedure is outlined, and equations for the sensitivity coefficients of several element types are tabulated.     

双/三模基片集成波导和共面波导混合结构滤波器设计

针对微波带通滤波器小型化、高性能的应用需求,提出使用双/三模方形基片集成波导和共面波导混合结构设计带通滤波器.通过改变双模基片集成波导中TE₁₀₂和TE₂₀₁的谐振频率和外部耦合的强弱,可实现具有近似椭圆、非对称和无传输零点响应的双模滤波器;两个相同尺寸的共面波导作为谐振器蚀刻在基片集成波导表面,与TE₁₀₂和TE₂₀₁共同形成一个通带,设计具有多样性响应的四阶滤波器.在具有非对称响应四阶滤波器的基础上,使主模TE₁₀₁频率移动到该通带附近,设计更宽带宽的五阶滤波器.并对设计的滤波器进行加工和测试.测试结果与仿真结果吻合,表明了该混合结构设计高性能滤波器方法的可行性.     

Fractal Dual-Mode Open-Loop Quasi-Elliptic Bandpass Filter with Source-Load Coupling

To realize the feature of small size and high selectivity, a microstrip miniature fractal quasi-elliptic bandpass filter (BPF) with two transmission zeros (TZs) near each skirt is investigated in this paper. The TZs are created by source-load coupling between the input and output E-shaped feeding structures. By using a dual-mode Minkowski fractal shorted stub loaded open-loop resonator, the proposed BPF achieved a size reduction of 97.5% compared with the conventional square dual-mode loop BPF. Even mode analysis is adopted to characterize the Minkowski structure. The frequency responses of the current BPF were simulated and measured with good agreement.     

The design of microstrip six-pole quasi-elliptic filter with linearphase response using extracted-pole technique

The development of microstrip filters has been in great demand due to the rapid growth of wireless communication systems in this decade. Quasi-elliptic response filters are very popular in communication systems because of their high selectivity, which is introduced by a pair of transmission zeros. A number of ways of implementing the quasi-elliptic response filter on microstrip have been studied over the last two decades, i.e., the cascaded quadruplet filter, canonical filter, and extracted-pole filter. However, there is very little information in the literature giving the design details for microstrip extracted-pole filters. In this paper, design equations of the extracted-pole filter for microstrip are reviewed. A new class of microstrip filter is also presented here. This class of filter will have a quasi-elliptic function response and at the same time linear phase in the passband. The linear phase of the filter is introduced by an in-phase cross coupling, while the transmission zero is realized using an extracted-pole technique. Experimental results, together with a theoretical comparison between the group delay of this design, and the conventional quasi-elliptic six-pole filter are also presented     

双模方形带通滤波器的分析、建模及设计

本文报道一种利用谐振器中缺口位置设计双模带通滤波器的新方法.用这种方法既可以实现具有一对传输零点的双模带通滤波器,也可以实现无传输零点的双模带通滤波器.通过分析缺口位置对谐振器内电场模式分布的影响,建立了双模滤波器的拓扑结构图.利用全波仿真软件,基于不同的缺口位置设计了中心频率为2.05GHz,带宽为100MHz的两种...     

Synthesis and design of in-line N-order filters with N real transmission zeros by means of extracted poles implemented in low-cost rectangular H-plane waveguide

In this paper, an extension to the extracted pole technique for synthesizing N-order filters with N-transmission zeros at real frequencies is presented. In addition, a new bandpass rectangular waveguide H-plane low-cost configuration filter for high-power low-loss application (patent pending) that implements a filtering function with finite real frequency transmission zeros is proposed. This structure operates as a resonant cavity in transmission at central frequency of the bandpass and simultaneously introduces a controlled transmission zero out of the bandpass. Since every double-controlled electrical behavior cavity introduces a transmission zero, it is possible to introduce as many transmission zeros as the order of the filtering function. In order to validate the synthesis procedure and the new structure, different filters have been designed: a second-order filter with two transmission zeros, a third-order filter with one transmission zero, a fourth-order filter with two transmission zeros, and finally, an eighth-order filter with two transmission zeros. The last two have been manufactured, showing an excellent agreement between the measurement and theoretical simulation.     

Compact Planar Quasi-Elliptic Function Filter With Inline Stepped-Impedance Resonators

Compact microstrip bandpass filters of orders N = 4,6, and 8 with quasi-elliptic function responses are synthesized with inline stepped-impedance resonators. The filters have enhanced transition responses since two transmission zeros are generated on both sides of the passband. Existence of these two zeros is investigated by formulating the Y-matrix of the equivalent circuit for the filter and taking adjacent and nonadjacent coupling into account. Some matrix elements Y_j,j+2 representing coupling between two nonadjacent resonators are shown to have the opposite signs in both the lower and upper sides of the center frequency. This property leads to creation of the two transmission zeros on both sides of the passband. It is demonstrated that one more zero can be created in the rejection band by the tapped-line input/output scheme. Experimental circuits on substrates with epsiv_r = 2.2 and 10.2 are measured to validate the theory and design.     

A Two-Stage SIR Bandpass Filter With an Ultra-Wide Upper Rejection Band

Two-stage stepped-impedance resonator (SIR) filters are designed to have a wide upper stopband. Two transmission zeros are also created near the passband to form a quasi-elliptic response. For a 20-dB rejection level, with properly designed SIR geometry and tapped-line structure, the leading three spurious resonances of the SIR are suppressed by transmission zeros and respective unmatched singly loaded Q (Q_si) values. Measured results illustrate that stopbands up to 8.4 and 5.3 times the design frequency can be achieved for rejection levels of 20 and 30dB, respectively     

Substrate integrated waveguide (SIW) asymmetric dual-mode filter and diplexer

Substrate integrated waveguide (SIW) can be used to implement high Q waveguide components with the same easy and low-cost fabrication process as planar circuits. In this paper two inline three-pole dual-mode filters with asymmetric transmission response based on SIW are presented. These two filters, consisting of a TE₁₀₂-TE₃₀₁ dual-mode SIW cavity and a TE₁₀₁ mode SIW cavity, are centred at around 10?GHz with a transmission zero on the left of the passband and the right of the passband, respectively. Based on the two kinds of three-pole deal-mode filters, a diplexer with isolation better than 35?dB is developed. A linear microstrip taper is used to implement the transition between microstrip and SIW. The measured results agree with simulated results.     

基于双模谐振器的W波段波导带通滤波器

带通滤波器为现代毫米波系统中进行频率选择的重要器件,而波导滤波器因其低损耗、大功率容量、易加工等优点成为首选。为满足系统的小型化要求,设计了一种基于双模谐振器且具有准椭圆函数响应的W波段波导带通滤波器。该波导带通滤波器结构简单紧凑,由两个双模方形脊谐振腔组成,可获得2 个传输零点及四阶准椭圆函数响应。滤波器样品选取紫铜材质,采用CNC 技术加工制作。经矢量网络分析仪测试,该滤波器通带内插损低,达0.5 dB,3 dB 波束带宽为4.35 %(92.2 ~96.3 GHz),回波损耗优于20 dB,通带外存在两个非对称零点。在全W波段的测试结果与仿真数据高度吻合。     

Design of an LTCC tri-band transceiver module for GPRS mobile applications

This paper presents the design and results of a low-temperature co-fired ceramic (LTCC) module for tri-band general packet radio service (GPRS) mobile applications. The proposed transceiver module integrates the tri-band (EGSM900/DCS1800/PCS1900) antenna switch, the surface-acoustic-wave filters for band selection, and a fully integrated tri-band transceiver integrated circuit into one LTCC package. By taking advantages of the three-dimensional layout capability of the LTCC substrate, the embedded circuit elements can be arranged vertically for size reduction. In addition, the utilization of mutual coupling leads to a novel design of miniature lumped-element realization of the transmission line. By combining these miniature passive component designs, the proposed module features a compact size of 13.8 mm /spl times/ 8.1 mm, with a packaged height of 1.8 mm. The module is compliant with the European Telecommunications Standards Institute regulations for GPRS mobile applications and is currently in use in commercially available mobile phones.     

Investigation of quasi-elliptic hairpin dual-mode filters under different perturbations

This article presents a dual-mode resonator developed from a hairpin resonator with a reactive perturbation tapped at the mid-point. The dual-mode resonance characteristics are investigated intensive under both inductive and capacitive perturbations. Using this resonator, a method of synthesising the filter is also developed to determine the circuit layout directly according to the specified filter characteristics. Moreover, to improve the filter's performance, cross-coupling technique to realise quasi-elliptic responses is also discussed for both types of perturbations. Finally, two quasi-elliptic dual-mode filters were designed, fabricated and measured to verify the proposed theory.     

Quadruple-Mode Coupled-Ring Resonator Bandpass Filter With Quasi-Elliptic Function Passband

Quadruple-mode coupled-ring resonator is used to design quasi-elliptic function bandpass filters (BPFs) with a relatively wide bandwidth. The resonator consists of a pair of coupled rings with two open stubs symmetrically tapped to the inner ring. The stubs are used to move a transmission zero near the center frequency to lower transition band. It is believed that it is the first ring resonator BPF based on the coupled-ring to create four transmission poles and four transmission zeros. Two filters with relative bandwidths of 10% and 15% are fabricated and measured. Good agreement between simulation and measurement is obtained.     

具有多传输零点的微波陶瓷滤波器设计

低温共烧陶瓷(LTCC)滤波器具有体积小、插损小和衰减大的特性,为了抑制其阻带信号,研究并设计了具有带外多个传输零点的多层LTCC带通滤波器,分析了传输零点对滤波器性能的影响.最后利用HFSS仿真软件设计了一个具有三级耦合谐振器、尺寸为2.5 mm×2.0 mm×0.9mm、中心频率为2.45 GHz的带通滤波器.仿真...     

Dual-Mode Dual-Band Filter With Band Notch Structures

A novel approach for designing dual-mode dual-band bandpass filters is proposed and experimentally studied. By embedding a pair of slits in the square patch, the dual-band response is realized and one transmission zero is introduced between the two passbands. Two degenerate modes are achieved by loading with a small square perturbation, which can be placed at the diagonal line. There are three transmission zeros. The slits control the first and third transmission zeros. On the other hand, the right crossed slots control the first and the second transmission zeros.      

Miniaturized Bandpass Filters With Double-Folded Substrate Integrated Waveguide Resonators in LTCC

This paper proposes miniaturized bandpass filters with double-folded substrate integrated waveguide (SIW) resonators using multilayer low-temperature co-fired ceramic (LTCC) technology. Formed by inserting a metal plate with two orthogonal slots into the cavity, the double-folded SIW resonator is used for the circuit size reduction with its footprint about a quarter of the conventional ${rm TE}_{101}$ mode. With LTCC technology, there is more flexibility to organize the cavities of filters because of the 3-D arrangement. The vertically stacked cavities are coupled by “L”- or “U”-shaped slots, and if arranged horizontally, by an inductive window on the common sidewall or a suspended stripline between the cavities. Through experimental measurements and simulations at both the $Ka$- $V$ -bands, it has been demonstrated that the proposed filter has compact sizes and good frequency responses. The area of the fully stacked Chebyshev filter has 88% size reduction in comparison with a three-pole planar waveguide filter, while the vertically stacked quasi-elliptic filter has 74% size reduction in comparison with a four-pole planar waveguide filter.      

Novel design possibilities for dual-mode filters without intracavity couplings

This letter presents coupling schemes and design guidelines for dual-mode filters without intracavity couplings. Examples of filters of orders two and four are presented to document the flexibility of these solutions. These coupling schemes allow the change of transmission zeros from either side of the passband to the other by only detuning the resonators and without changing the coupling coefficients.