ie3d教程chap10.docx

ie3d教程chap10.docx

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ie3d教程chap10

Chapter10SimulationofRFandMicrowaveFilters

PlanarfiltersareimportantcomponentsinRF,wireless,andmicrowavecircuitsandsystems.IE3Disageneral-purposeelectromagneticsimulator.Itcertainlycanbeappliedefficientlytotheanalysisanddesignofdifferentkindsofplanarand3Dfilters.

Afilternormallyconsistsofmultiplecloselycoupledresonators.Ifweadjusttheresonantfrequenciesoftheresonatorsandthecouplingbetweentheresonatorsproperly,wecanachievehighperformancefilters.Todesignafilter,wecancertainlystartfromtheIE3Ddirectly.However,nomatterhowfastitis,IE3Disstillafull-waveEMsimulator.Itwouldbenicethatwecanstartfromsomeinitialgeometry.Forthisreason,wehavedevelopedtheFilterSynmodulefortheIe3dLibrary.

Section1.Ie3dLibrary,theParameterizedandObject-Oriented2ndInterfaceforIE3D.

Ie3dLibraryisthe2ndinterfacedevelopedforIE3D.WehavebeenusingtheMGRID,thedefaultinterfacefortheIE3Dinthepreviouschapters.Asyoucansee,MGRIDisaverypowerfulgraphicinterface.Itallowsyoutoconstructandeditcomplicatedstructureswithalldetails.ThefundamentalelementsofMGRIDarepolygonsandvertices.MGRIDallowsyoutocontroltheshape,size,andorientationofpolygonsandthelocationsofvertices.Wecanconstructalmostanykindofshapeseasily.However,polygonsandverticesarelowlevelobjects.Considerafilter,itmayconsistofmanydifferentpolygons.Therearerelationsbetweendifferentpolygonsofafilter.OntheMGRID,wecanchangetheshapeandsizeofapolygoneasily.However,ifsomedimensionsofanobjectaredeterminedbymanyverticesorpolygons,itmaybetedioustochangethembychangingeachpolygononebyone.Forthisreason,weintroducedtheIe3dLibrary.ThebasicelementsofIe3dLibraryaretheobjectsofpre-definedshapes.Thedimensionsoftheobjectscanbechangedanytimeafteritiscreatedasabuildingblockforalargecircuit.Forexample,wecandivideacircuitasobjectsofT-junctions,cross-junctions,Y-junctionsandstraightlines,etc.ontheIe3dLibrary.Wecanconnectdifferentobjectsusingsomedefaultsnappingscheme.Afterthecircuitisbuilt,wecanstillchangeeachelement’sdimensions.Whenwechangethedimensionsofanobject,Ie3dLibrarywillpreservetheconnectivitybetweentheobjects.Wecanalsodefinetuningvariableswithadimensionofanobjectdescribedasaformulareferencingthetuningvariables.Whenwechangethetuningvariables,thedimensiondefinedbytheformulaisupdatedautomatically.Buildingalargestructurewithpre-definedobjectshapesbecomesmuchsimplifiedontheIe3dLibrary.

InIE3D12,IE3DLIBRAYismuchimproved.Booleanobjectsandoperations,voidobjecsareintroducedandtheyextendthegeometrymodelingcapabilityofIE3DLIBRARYtoanextlevel.WehavealsoimplementtheFastEMDesignKitdiscussedinChapter5intoIE3DLIBRARY.Thecombinationsofequation-basedgeometrymodeling,BooleanobjectsandoperationsandFastEMTuningandOptimizationmakeIE3DandIE3DLIBRARYmuchmorecapablethanbefore.AseparatedocumentonusingIE3DIBRARYisprovided.Interesteduserspleasereadthedocumentformoreinformationinusingthisgreatlayoutandparameterizationtool.

Section2.UsingFilterSynModuleforIe3dLibraryforInitialDesign.

TheFilterSynmoduleisbasicallyamenuitemontheIe3dLibrary.TheFilterSynisnotconsideredaspartoftheIE3D.WewilldemonstratehowtousetheFilterSyntogetinitialdesignintheexamplesinthischapter.ThoseuserswhodidnotpurchasetheFilterSynwillnotbeabletousetheFilterSynmoduletocreatetheinitialdesign.YoucangetthecreatedgeometryfilesfromFilterSynfromthe.\ie3d\samplesdirectory.IfyouareinterestedinthelicenseofFilterSynmodule,pleasecontactusat:

info@.

TheFilterSyndealswithlow-pass,bandpass,andbandstopfilters.Itcoverscoaxial,microstrip,stripline/LTCC,andstripline-likestructures.Itcontainsanalyticalmodelsofthefollowingfilters:

steppedimpedancelow-passfilters,open-circuitedstublow-passandbandstopfilters,parallel-coupledbandpassfilters,gap-coupledbandpassfilters,andcomblineandinterdigitalbandpassfilters.Thereare4typesoflow-passfilters,20typesofband-passfilters,andonetypeofband-stopfilters.EachfiltertypecanbeusedasanobjectoftheIe3dLibrary.Wewilldemonstratehowtouseitinthefollowing.

Step1RunIe3dLibrary.AnemptyIe3dLibrarymainwindowpopsup.SelectFile->Newcommand.Ie3dLibrarywillpromptyoufortheNewProjectWizard.SelectStartaNewFilterSynProject,andselectOK.Thedialog“FilterSimulationandSynthesisModuleforIe3dLibrary”comesup.

Figure10.1TheFilterSyndialogforIe3dLibrary.

Step4CheckLow-PassinFiltersgroupandcheckMicrostripinTransmissionLinesgroup.WewillgetthepictureshowninFigure10.1.Thereare2typesofLow-PassMicrostripFiltersavailable.

Figure10.2TheSimulationandSynthesisSetupdialogforthelow-passfilter.

Step5PleaseselectMicrostripStepped-ImpedanceLow-PassFilteronthelist.

IfyoudonothavetheFilterSynlicense,Ie3dLIbrarywillgiveyouawarning.PleaseskipthissectionandgotoSection3.

IfyouhavetheFilterSynlicense,thesetupdialogforthefiltertypecomesup.Theparametersfortheobjectaredividedinto3groups:

（1）CommonParameters,

（2）SimulationParameters,and（3）SynthesisParameters.Ifwearesimulatingamicrostripstepped-impedancelow-passfilterwithpre-definedparameters,wecanenterthecorrespondingparametersintheCommonParametersandSimulationParametersgroups.Ifwearesynthesizingafilterwithspecifiedperformancerequirements,weshouldentertheparametersintheCommonParametersandSynthesisParametersgroup.Inourexample,wearegoingtosimulatethefilterwiththedefaultparameters.

Step4ClicktheSimulatebuttoninthedialog（seeFigure10.2）.FilterSynwillfinishthesimulationinnotimesinceitisbaseduponanalyticalformulas.Then,itwillpromptyouforthes-parameterfile.

Step5Pleasetype:

.\ie3d\practice\output\lpfa.spandselectSavebutton.Theresultings-parametersaresavedintothefileandMODUAisinvokedtodisplaythes-parameters（seeFigure10.5）.

Youmaywonderhowaccuratetheresultsare.YoumaywanttochecktheresultsusingIE3D.WearegoingtocreatetheIE3Dmodelforit.Wedonotneedtoenterthepolygonsbaseduponthedimensions.WecancreatethemautomaticallyontheIe3dLibrary.

Step6SelectOKtoclosetheMicrostripStepped-ImpedanceLow-PassFilterdialog.ItwillgetbacktotheFilterSimulationandSynthesisModuleforIe3dLibrarydialog.

Step7WhiletheMicrostripStepped-ImpedanceLow-PassFilterisstillbeingselected（seeFigure10.1）,pleaseselecttheCreateLibFilebutton.Thecompletelow-passfilterbecomesanobjectoftheIe3dLibrary.Itisfollowingthemousecursorforrelocation.

Step8ClickthemousebuttonsomewhereintheIe3dLibrarywindow.Theobjectisdroppedontothewindow.However,itisstillbeingselectedwiththecornershighlighted（seeFigure10.3）.Clickatanemptyspottode-selecttheobject.Saveitas:

.\ie3d\practice\lpf1.ie3.Theextension“.ie3”isforIe3dLibrary.Youwillseetwored-dotsonthetwoendsofthefilter.Theyarethepossibleconnectionpointsfortheobject.Youcanconnectotherobjectstotheedgeswithred-dotsonly.

Figure10.3LPF1droppedontoIe3dLibrary.

Section3.UsingLineGaugeforTransmissionLineParameters.

IfyoudonothavetheFilterSynlicenseandyouhaveskippedthelastsection,pleaseopenthefile:

.\ie3d\samples\lpf1.ie3onIe3dLibrary.Saveitas:

.\ie3d\practice\lpf1.ie3.Wearegoingtodiscusstheotherfeatureshere.

Wearegoingtoadda50-ohmlinesectiontoeachendofthefilter.Whatisthewidthofa50-ohmmicrostriplinewitha10-mil-thicksubstrateofdielectricconstant9.9?

Itdoesnotmatterwhetheryouknowit,becauseyoucanusetheLineGaugeTransmissionLineSynthesisTooltodothesynthesis.ThebasiceditionoftheLineGaugeisfreeofcharge.Youcananalyzeandsynthesizesimpletransmissionlinessuchasmicrostrip,stripline,andcoplanarwaveguideusingthebasiceditionoftheLineGauge.FortheprofessionalversionoftheLineGauge,pleasecontactZelandSoftware,Inc.

Step9RunLineGauge.SelectMicrostripinthelistbox.SelectLengthUnit=mil.EntertheFrequency=3GHz,RelativePermittivity=9.9,SubstrateHeighth=10mils,StripThickness=0.1.Then,enterKeyElectricalParametersas:

Zc=50andElectricalLength=30degrees.SelectthebuttonElectrical->PhysicalParameters.LineGaugewillcalculatethephysicalparametersbaseduponthecommonparametersandtheelectricalparametersandyieldstheStripWidth=9.49milsandtheLength=128mils（seeFigure10.4）.The30-degrees（or128mils）isanarbitrarilychosenanditisnotcritical.Wewilladda50-mil-longsectionoftransmissionlinetoeachend.

Figure10.4TheLineGaugewindow.

Section4.ConnectingObjectsonIe3dLibrary.

Step1PleaseselectEdit->BasicParametersdialog.Pleasemakesurethelengthunitis“mil”.ItispossibletheIe3dLibrarylayoutmaynotusethesamelengthdimensionastheFilterSynmodule.

Step2OnIe3dLibrary,selectInsert->StripObjects.Youwillseeasub-menuwithmorethan10menuitemscomesup.Eachmenuitemcorrespondstoaparameterizedobjectofpre-definedshape.

PleaseselectInsert->StripObjects->StraightStripcommand.ThedialogforStraightStripobjectcomesup（seeFigure10.5）.EnterLength=50milsandtheWidth=9.49mils.SelecttheZ=10mils.ThereisaparameterforStripType.Itdefin