《现代微波电路和器件设计》课件5、高效波导滤波器设计

1、现代微波电路和器件设计5、高效波导滤波器设计苏 涛2008年春高效波导滤波器设计波导滤波器设计 Step-by-Step高效波导滤波器设计波导滤波器设计实例高效滤波器设计实例波导滤波器其它设计工具简介、波导滤波器设计 Step-by-stepport 2port 1a/2bwidth1width2width3width2width1length1length2length2length1symmetryboundary- optimization of one dimension in each step耦合膜片设计传输线段设计设计步骤1、由滤波器指标得到原型电路：得到K变换器的值；2、膜片尺

2、寸设计（耦合设计）：使用HFSS优化膜片尺寸，得到要求的K变换器的值对应膜片的尺寸；3、传输线尺寸设计（谐振器设计）：得到各传输线段的长度优点： 每一步仅仅有简单结构仿真，速度快； 每一步仅仅有一个优化变量，收敛快速；（1a）由指标得到低通原型电路1、滤波器原型电路设计（1b）电路变换，得到K变换器的值2、耦合设计（子问题1）3、传输线段（谐振腔）设计（子问题2）为什么可以把滤波器设计分解为两类典型的问题？1、根据滤波器的等效电路：膜片提供耦合，波导段等效谐振腔；2、耦合和谐振腔两类问题，特别是膜片耦合，组合在一起时，各自的参数没有发生明显的变化；模式、模式间作用上述方法其实就是“网络方法”；

3、把耦合和波导段都等效为两端口网络；网络的特性与尺寸相关；滤波器的特性就是网络级联的结果。注意到波导段是简单的传输线网络，其特性完全可以由网络理论直接得到，不必再对其进行全波仿真；全波仿真准确，但是费时费力；网络理论简单快捷，但只针对典型问题有效；结合两者，可以得到“高效”的设计方法2、高效波导滤波器设计AnsoftDesigner结合设计微波波导系统结合电路和全波分析很多问题都可以分解为若干关键部分波导滤波器和腔体滤波器超大规模电路：封装制版元件传输线或波导连接的各个部件广义的传输线连接问题传输线等简单问题可以由电路理论得到结果；复杂问题可以由全波仿真得到其参数；总问题是各个分问题的联合；“分

4、而治之”的策略可以得到高效而准确的结果首要确定的是：分解大问题的策略是否适用？是否能得到准确解？求解子问题，并把子问题的特性与其结构的关系参数化；建立大问题的模型，其由各个小部分组成；由于小问题已经实现的特性参数化，很容易的对大问题进行分析和优化。HFSS中的说明：有限元用于求解任意三维结构中的Maxwell方程Finite Element Method无限元用于求解端口处的两维场分布Transfinite Element Methodzand characteristic impedance (specifies a relationship between E and H)propagat

5、ion constantattenuationA single port solution (mode) yields a propagation constantHFSS中的说明：广义S参数全面的描述了三维结构的“黑箱”特性；“black-box”端口相同，但是内部结构不同的部分，可以分别计算，并在端口处相连；HFSS中由无限元法确定的广义S参数保证了在端口边界处“场匹配”相同模式的场相同。模式由什么确定？内部结构？端口边界条件？The basic approachSelect the building blocks (parametric models) for the desired s

6、tructure.Verify the technique on a simple, easily verifiable model.Define the parameter space: what range of values should the parameters cover?Synthesize and optimize the desired three-dimensional structure using parametric models generated from HFSS.Verify the design using the full-wave solution o

7、f the entire structure.摘自Ansoft资料分解 依据验证参数化 范围优化全波校正3、波导滤波器设计实例中心频率：3599MHz带宽：35853615，可做40MHz抑制度：25dB3535/3665MHz60dB3425/3765MHz70dB3385/3815MHz国家标准BJ40 波导 Ansoft公司的相关资料说明 上面波导滤波器实例工程The waveguide filter is comprised of e-plane irises that have been characterized parametrically in HFSS.12345Parame

8、tric model based on full-wave analysis.S-parameters depend on frequency and aperture width.dRealization of a Waveguide Filter1. Define parameterized model by generating a grid of coarsely spaced solutions in the parameter space.Realization of a Waveguide Filter2. Create the entire filter from indivi

9、dual components.The model is fully parameterized!Parameterized Port ImpedanceAn important aspect of the circuit model is the frequency dependent port impedance:if(kkc10,z10,0)Z10 is the frequency dependent characteristic impedance.Realization of a waveguide filter3. Optimize the filter response by “

10、interpolating existing solutions.”The accuracy of the full-wave analysis is accessible by interpolating existing solutions!Realization of a Waveguide Filter3. Optimization continued: the goal response for the optimization can be generated using the filter synthesis tool.Optimized response using inte

11、rpolation of coarsely spaced HFSS solutionsOptimization goalComparison between HFSS and Ansoft DesignerHFSSDesigner|S21|S11|4. Improve the solution accuracy by generating exact full-wave solutions for the optimized parameter values.波导滤波器实例HFSS工程1：关于膜片，单侧电感膜片HFSS工程2：关于波导段注意：波导端口特性阻抗的计算，在此处要采用Zpv，才能与D

12、esigner结合。Designer工程：插入HFSS工程作为“子电路” Designer中加入HFSS工程，要选择第几次叠代结果，一般应选择Setup？:Sweep HFSS工程必须是扫频的，而且选定为Fast Sweep，这样Designer才可以使用插值算法；3、高效滤波器设计实例Example 2: dielectric/coaxial resonator cavity filterWaveguide components are generally simple because the behavior is accurately described by single mode i

13、nteraction between components.How do we approach structures that are not easily described by single mode behavior?Use the example of a mixed resonator filter to investigate the approach.Single Dielectric ResonatorAs usual, take advantage of the symmetry when possible for full-wave analysis.E-fieldH-

14、fieldPerfect E-symmetry planeAnalysis of a Single Dielectric Resonator A single resonator cavity is perfect for investigating the proposed approach because solutions can be obtained very fast, and various methods can be used to obtain the same information.1.Resonant frequency and Q determined from t

15、he Eigenmode solver in HFSS.2.Solve the driven problem with port excitations (also gives resonant frequency and Q)3. Create a parametric model in HFSS and analyze this model by matching port modes in Ansoft Designer (the transfinite element method).Subdivision of Dielectric ResonatorsEigenmode solve

16、r, driven solution, and transfinite element analysis were used to verify the equivalence of the three analysis methods.+=3-dimensional Eigenmode solutionPort solutionDefining Parameter SpaceThe equivalent circuit can be equated to physical dimensions by equating resonant frequencies of the two simul

17、ations.Open circuit = perfect magnetic conductorShort circuit = perfect electric conductorDesign and Analysis of a 5 pole filter3 parametric models are required to create this filter.5 Pole Cavity FilterOnly 3 Modes are needed to represent the TE01d Dielectric resonator mode.Generated in HFSSOptimiz

18、ation goal is inserted in the same schematic as the HFSS subcircuitsEach connection represents a mode (port solution)5 Pole FilterFilter synthesis is carried out in Designer, using parameterized models that were generated in HFSS.“Simulate missing solutions”Solution in Designer when HFSS models are interp