《現(xiàn)代微波電路和器件設計》課件6、高效波導濾波器設計

1、現(xiàn)代微波電路和器件設計 6 、 高效波導濾波器設計蘇 濤2010年春高效波導濾波器設計波導濾波器設計 Step-by-Step高效波導濾波器設計波導濾波器設計實例高效濾波器設計實例波導濾波器其它設計工具簡介、波導濾波器設計 Step-by-stepport 2port 1a/2bwidth1width2width3width2width1length1length2length2length1symmetryboundary- optimization of one dimension in each step耦合膜片設計傳輸線段設計設計步驟1、由濾波器指標得到原型電路：得到K變換器的值；2、

2、膜片尺寸設計（耦合設計）：使用HFSS優(yōu)化膜片尺寸，得到要求的K變換器的值對應膜片的尺寸；3、傳輸線尺寸設計（諧振器設計）：得到各傳輸線段的長度優(yōu)點： 每一步僅僅有簡單結構仿真，速度快； 每一步僅僅有一個優(yōu)化變量，收斂快速；（1a）由指標得到低通原型電路1、濾波器原型電路設計（1b）電路變換，得到K變換器的值2、耦合設計（子問題1）3、傳輸線段（諧振腔）設計（子問題2）為什么可以把濾波器設計分解為兩類典型的問題？1、根據(jù)濾波器的等效電路：膜片提供耦合，波導段等效諧振腔；2、耦合和諧振腔兩類問題，特別是膜片耦合，組合在一起時，各自的參數(shù)（TE10模式的網(wǎng)絡參數(shù)）沒有發(fā)生明顯的變化；模式、模式間作

3、用上述方法其實就是“網(wǎng)絡方法”；把耦合和波導段都等效為兩端口網(wǎng)絡；網(wǎng)絡的特性與尺寸相關；濾波器的特性就是網(wǎng)絡級聯(lián)的結果。注意到波導段是簡單的傳輸線網(wǎng)絡，其特性完全可以由網(wǎng)絡理論直接得到，不必再對其進行全波仿真；附：關于模型（網(wǎng)絡）的討論1、不同的模型，研究的問題不同；要注意性質和適用范圍；模 型理論和算法集總電路器件：集總元件；線：拓撲連接基爾霍夫定律分布電路（器件級別）器件：分布或集總線：傳輸線微波網(wǎng)絡結構電路器件：結構、材料線：結構電磁場數(shù)值分析MoM、FEM、FDTD參考文獻：Microwave Office V8，Example:18GHz_LPF低通濾波器設計集總電路模型分布電路模型

4、 1分布電路模型 2？ 與前者有何異同結構模型2、建模、分析和綜合都是建立在理論分析之上的，網(wǎng)絡理論的應用要理解物理本質，并注意網(wǎng)絡處理手段的特點；例如：膜片形式器件的網(wǎng)絡綜合策略在波導濾波器和圓極化器中的不同；2、高效波導濾波器設計AnsoftDesigner結合設計微波波導系統(tǒng)結合電路和全波分析很多問題都可以分解為若干關鍵部分波導濾波器和腔體濾波器超大規(guī)模電路：封裝制版元件傳輸線或波導連接的各個部件廣義的傳輸線連接問題傳輸線等簡單問題可以由電路理論得到結果；復雜問題可以由全波仿真得到其參數(shù)；總問題是各個分問題的聯(lián)合；“分而治之”的策略可以得到高效而準確的結果首要確定的是：分解大問題的策略是

5、否適用？是否能得到準確解？求解子問題，并把子問題的特性與其結構的關系參數(shù)化；建立大問題的模型，其由各個小部分組成；由于小問題已經(jīng)實現(xiàn)的特性參數(shù)化，很容易的對大問題進行分析和優(yōu)化。HFSS中的說明：有限元用于求解任意三維結構中的Maxwell方程Finite Element Method無限元用于求解端口處的兩維場分布Transfinite Element Methodzand characteristic impedance (specifies a relationship between E and H)propagation constantattenuationA single por

6、t solution (mode) yields a propagation constantHFSS中的說明：廣義S參數(shù)全面的描述了三維結構的“黑箱”特性；“black-box”端口相同，但是內(nèi)部結構不同的部分，可以分別計算，并在端口處相連；HFSS中由無限元法確定的廣義S參數(shù)保證了在端口邊界處“場匹配”相同模式的場相同。模式由什么確定？內(nèi)部結構？端口邊界條件？The basic approachSelect the building blocks (parametric models) for the desired structure.Verify the technique on a

7、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 of the entire structure.摘自Ansoft資料分解

8、 依據(jù)分析參數(shù)化 范圍優(yōu)化全波校正3、波導濾波器設計實例中心頻率：3599MHz帶寬：35853615，可做40MHz抑制度：25dB3535/3665MHz60dB3425/3765MHz70dB3385/3815MHz國家標準BJ40 波導 Ansoft公司的相關資料說明 上面波導濾波器實例工程The waveguide filter is comprised of e-plane irises that have been characterized parametrically in HFSS.12345Parametric model based on full-wave analy

9、sis.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 individual components.The model is fully

10、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 “interpolating existing solutions.”T

11、he 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 interpolation of coarsely spaced HFSS s

12、olutionsOptimization goalComparison between HFSS and Ansoft DesignerHFSSDesigner|S21|S11|4. Improve the solution accuracy by generating exact full-wave solutions for the optimized parameter values.波導濾波器實例HFSS工程1：關于膜片，單側電感膜片HFSS工程2：關于波導段注意：波導端口特性阻抗的計算，在此處要采用Zpv，才能與Designer結合。Designer工程：插入HFSS工程作為“子電路

13、” Designer中加入HFSS工程，要選擇第幾次疊代結果，一般應選擇Setup？:Sweep HFSS工程必須是掃頻的，而且選定為Fast Sweep，這樣Designer才可以使用插值算法；3、高效濾波器設計實例Example 2: dielectric/coaxial resonator cavity filterWaveguide components are generally simple because the behavior is accurately described by single mode interaction between components.How d

14、o 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-fieldPerfect E-symmetry planeAnalys

15、is 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 the Eigenmode solver in HFSS.2.Solve

16、 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 solver, driven solution, and transfinite

17、 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 simulations.Open circuit = perfect magne

18、tic 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 HFSSOptimization 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