HFSS 电磁仿真 最简单教程

Dr.RyanS.AdamsMarch12,2008

ThistutorialintroducestheinterfaceofAnsoft’sHFSS,andwalksthestudentthroughanexampleproblemofcreating,simulatingandevaluatingtheresponseofastandardstriplinestructure.

1StartingHFSS

AtUNCC,theHFSSapplicationresidesonaLinuxbasedserverbythenameof“hertz”whichispartoftheReconfigurableComputingSystem(rcs).ThebestwaytoaccessthisserveristhroughtheMosaicsystem.

1.1LoggingIntoMosiacLinuxServer

WhenyouareloggedintooneoftheMosaicwindowscomputers,youfirstneedtologintoExceedLinux.Thisisdonebyselectingthestartmenu=>AllPrograms=>MOSAICXP=>UnixConnectivity=>ExceedLinux,asshowninFigure1.1.ThisshouldbringyoutoascreenthatlookssomethinglikeFigure1.1.Inthebox,lxs-sm1andlxs-sm2areidenticallinuxserversthataremaintainedbyMosaic.HighlightwhicheveroneyoupreferandclickOK.YoushouldthenbepresentedwithaloginscreenforRedHatEnterpriseLinux5;useyournormalMosaicloginIDandpasswordtologintothelinuxserver.

1.2LoggingintotheReconfigurableComputingSystemNetwork

Atthisstage,youshouldbelookingatalinuxdesktop(probablywitharedbackground).TologintotheRCSnetwork,startfromacommandprompt.Todothis,rightclickanywhereonthedesktopandclick“OpenTerminal”inthepop–downmenuthatappears.Intheterminalthatappearsperformthefollowingcommands:

1.typessh-C-Yrcsyoushouldnowbepromptedtologintothercssystem–donotuseyourmosaicpassword,useyourrcspasswordinstead.ssh-C-Yhertzyoushouldnowbepromptedtologintohertz–usethe2.type

samepasswordthatyouusedtologintothercsnetwork.3.type

hfss

andwaitafewmomentsfortheguitoappear.

1

Figure1:PathinWindowsMosaictoaccessExceedLinuxservers.

Figure2:SelectingaLinuxserver.

Note:Thefirsttimeyoulogintohfss,itwillpromptyouforcertainfilelocations.Usethedefaultsandfollowthepromptsuntiltheguiappears.Youmayfindyourselfbackatacommandprompt.Ifthishappens,justretypehfssandtheguishouldcomeup.

2TheHFSSInterface

ThemainHFSSinterfaceisshowninFigure2,whichillustratesthemaincomponentsofthegui.Theyaresummarizedasfollows:

•3DModelerWindowThisistheareawhereyoucreatethemodelgeometry.Thiswindowconsistsofthemodelviewarea(orgrid)andthehistorytreeasshowninFigure2.Thehistorytreedocumentstheactionsthathavebeentakeninthemodelviewarea,andprovidesanalternativewaytoselectobjectsinthemodelviewarea.•ProjectManagerwithProjectTreeTheprojectmanagerwindowdisplaysdetailsaboutallopenHFSSprojects.Eachprojectultimatelyincludesageometricmodel,itsboundaryconditionsandmaterialassignments,andfieldsolutionandpostprocessinginformation.AnexpandedviewoftheprojectmanagerisshowninFigure2•PropertiesWindowThepropertieswindowconsistsoftwotabs.Thecommandtabdisplaysinformationaboutanactionselectedinthehistorytreethatwasperformedtoeithercreateanobjectormodifyanobject.Theattributetabdisplaysinformationaboutthematerialanddisplaypropertiesofaselectedobject.

•ProgressWindowThiswindowisusedwhenasimulationisrunningtomonitorthesolution’sprogress.

•MessageManagerThiswindowdisplaysmessagesassociatedwithaproject’sdevel-opment(suchaserrormessagesaboutthedesign’ssetup)

3SettingupHFSS

BeforeyoucanuseHFSSforthefirsttime,thereareacoupleofitemsthatneedtobeconfiguredforefficientandaccurateoperation.

1.OntheToolsmenu,selectOptions=>GeneralOptions...,clicktheDefaultUnitstabandensurethatLengthissettomm.ClickOK.2.OntheToolsmenu,selectOptions=>HFSSOptions...,ensuretheIncludeferritematerialscheckboxischecked.ClicktheSolvertab,setthenumberofProcessorsto4,DesiredRAMLimit(MB)to6000andtheMaximumRAMLimit(MB)to8000.ClickOK.YoushouldnowbereadytouseHFSS.

ProjectManagerwithProjectTree

3D󰀀ModelerWindow

PropertyWindow

MessageManager

ProgressWindow

Figure3:MainscreenofHFSS.

4AnExample:ASimpleStriplineCircuit

Tobegintoappreciatethefunctionalityofthissimulationtool,wewillcreateandsimulateasimplestriplinetransmissionline.Beforewecanbegintoworkthroughthesimulation,weneedtodesignthecircuitonpaper.Wewishtodesigna50Ωstriplinetransmissionlinethatis10cmlongusingteflon(󰀁r=2.08,tanδ=0.0004).Theoverallmaterialthicknesswe’ll

√

choosetobe1cm.Therefore,eprZ◦=72.11<120andthefollowingequationshouldbeusedtocomputethetracewidthofthistransmissionline:

W30π=√−0.441.b󰀁rZ◦

(1)

Withourchoiceofmaterialthickness,W=0.866cm.

Nowthatwehavethegeometrycompletelydefined,wearereadytoopenHFSSandbuildthemodel.We’lldothisinthe3Dmodelerwindow.

4.1CreatingtheDielectric

Thefirstcomponentofthegeometrythatwe’lldrawisthedielectric.Thisisasolidrectangleofteflon,whichcanbedrawnbyselectingDraw=>boxinthefilemenu.Tomaketheboxthecorrectsize,youcaneither

1.inputthex,y,zcoordinatesofeachcomponentoftheboxintotheappropriatefieldsatthebottomofthe3Dmodelwindow,or

HistoryTree

ModelViewArea

Figure4:3DModelerWindow,whichconsistsofthemodelviewareaandthehistorytree.2.clickrandomlyinthe3Dmodelwindowthreetimestocreateaboxandeditthesizeinthepropertiesbox.Todothis,clickthecommandtabinthepropertiesboxandinputthecorrectstartposition,andxsize,ysizeandzsizeforourbox.Forourstriplinecircuit,wewanttoboxtobe200mminthex-direction,40mminthey-directionand10mminthez-direction.Theboxshouldstartatthelocation(-100mm,-20mm,-5mm)withXSize=200mm,YSize=40mmandZSize=10mm.Thematerialparametersaresetbyclickingontheattributetabinthepropertieswindow.ClickontheblockthatsaysVacuumandawindowshouldopentitled“SelectDefinition.”HighlightTefloninthematerialslistandclickOK.Ifyouwishtochangethecolorortransparencyoftheboxyoumayalsodosointheattributetab.

Atthispoint,theboxshouldcovertheentirescreen.Toviewtheentirebox,clickthebuttonwithapictureofamagnifyingglasswithawhitesquareinthemiddle.Thisbutton“fitsallthecontentsintheview.”Allthatremainsistocreatethecentertraceofthestripline.

4.2CreatingtheCenterTrace

Wewillcreatethecentertraceasaninfinitesimallythinstrip.Todothis,weselectDraw=>rectangleinthefilemenu.Wecandefinethesizeandlocationoftherectangleinthesamemannerasforthedielectricabove.Ourstripwidthis8.66mm,and1000mmlong,sothepositionis(-100,-8.66/2,0)andXSize=200mm,YSize=8.66mm.Sincethetracehasnothickness,wedonotapplyanymaterialattributestoit.Wewillmakeitintoaconductorusingtheboundaryconditions.

Figure5:ProjectManagerwindowillustratingthebounderyconditions,excitation,etc.ofthecurrentmodel.

4.3BoundaryConditions

Thefollowingboundaryconditionsmustbeappliedtothisdevice:

•PerfectEboundaryonthetopofthedielectric(simulatesametallayer)•PerfectEboundaryonthebottomofthedielectric(simulatesametallayer)•PerfectEboundaryonthetrace(simulatesametallayer)

•Radiationboundaryonthelongsidesofthedielectric(simulatesthematerialextendingtoinfinityinthatdirection)

Toapplytheseboundaryconditions,rightclickinthe3Dmodelerwindowandclick“SelectFaces”.Now,selectthetopface,bottomfaceandthestripusingthecontrolkey.Note:toselectfacesbeneathwhatyoucansee,clickthefaceyouwantandpressthe“b”keyuntilthedesiredfaceisselected.Withthesethreeitemsselected,rightclickinthe“white–space”ofthe3Dmodelerwindowandhighlight“AssignBoundary,”andclick“PerfectE...”.ClickOK.Next,selectthelongsidesofthedielectricusingthecontrolkey.Rightclickinthewhite–spaceofthe3Dmodelerwindowandhighlight“AssignBoundary,”andclick“Radiation...”ClickOK.

Tocheckthattheboundariesarecreatedcorrectly,expandthe“Boundaries”itemintheProjectTree,andyoushouldsee“PerfE1”and“Rad1”orsimilar.HighlightPerfE1,andyoushouldseehashmarksindicatingwhichregionsofthemodelapplytothisboundary.HighlightRad1toseethesameinformationfortheradiationboundary.

4.4Excitations

Wewillcreatea“Waveport”excitationateachendofthecircuit.Todoso,weperformthefollowingsteps:

1.Selectthefaceofthenearestendofthecircuit

2.rightclickinthe3DmodelerwindowandselectAssignExcitation=>WavePort.3.ClickNext

4.Under“IntegrationLine,”clickthewordNone,andselectNewLine...

5.Inthe3Dmodelerwindow,clickthecenterofthebottomoftheselectedface(atrianglewillappear)6.Clickthecenterofthetrace7.ClckNext8.ClickFinish

Thesamestepsshouldbeperformedtocreateawaveportattheotherendofthecircuit.

4.5Analysis

Performthefollowingstepstosetuptheanalysisoptions:

1.RightclickonAnalysisintheProjectTree,andselect“AddSolutionSetup”2.UndertheGeneraltab:

(a)Setthesolutionfrequencyto20GHz(b)Setthemaximumnumberofpassesto30(c)SetmaximumDeltaSto0.013.UndertheOptionstab:

(a)SettheMaximumRefinementperpassto20%(b)SettheOrderofBasisFunctionstoSecondOrderPerformthefollowingstepstosetupthefrequencysweep:

1.UndertheAnalysisitemintheProjectTree,right-clickonSetup12.SelectAddFrequencySweep...3.Setstartfrequencyto1GHz4.Setstopfrequencyto20GHz5.Setstepsizeto0.25GHz6.ClickOK

4.6FinalChecksandRunningtheSimulation

SelectHFSS=>ValidationCheck...toensuretheprojectispreparedforsimulation(clickclose).

Savetheprojectbyclickingonthesaveiconatthetopofthescreen.

Right-clicksetup1underAnalysisintheprojecttree,selectAnalyzetobeginthesim-ulation.Atthispointtheprogresswindowshouldshowtheprogressofthesimulation,beginningwiththemeshgeneration.

4.7SimulationResults

Toviewtheresultsofthesimulation,performthefollowingsteps:1.RightclickontheresultsitemintheProjectTree

2.ClickCreateModalSolutionDataReport=>RectangularPlot

3.Underthetracetab,selectthefirstS-ParameterthatyouwishtoviewandclickNewReport4.AddadditionalS-ParametersbyhighlightingthemandclickingAddTrace5.ClickClose