CST仿真色散图流程

[e-mail][Dispersiondiagram:CSTMicrowaveStudio]1Oneofthemostimportantreportsinmetamaterialtopicsis“Dispersioncurve”,whichdeterminestheband-gapbehavioroftheband-gapstructures.InthisarticletwoexamplesthatcouldclearlyshowtherightwayofgettingthisreportincludingtwoextraMatlabcodescripts,arepresented.IhopethisarticlecouldbehelpfulforthestudentswhoareloveElectromagnetic!“ThankstoDrMiguelNavarro-CíaImperialCollegeLondonforhisvaluablecomment”.DispersionDiagramExample1:SlowWaveHelixGeneralDescriptionThisexampledemonstratesaneigenmodecalculationusingperiodicboundariesinz-directionandaverymeaningfulexampleforshowinghowwecangetthedispersiondiagraminCSTMWSforperiodicstructures.ThisexamplealreadyisavailableinexamplefolderofCSTMWSinpathof:“C:\ProgramFiles(x86)\CSTSTUDIOSUITE2013\Examples\MWS\Eigenmode\TET\SlowWave\helix.cst”Structuredescription:Innerconductor(Fig.1(a))isahelicalmetalribbonwhichhasbeenholdbythreedielectricbricks(d)insideaPECcylindricalhole(b)asouterconductor.Fig.1(a)innerconductor(b)outerconductor(c)vacuum(d)dielectricholderFrequencyRangeThefrequencyrangestartsatDCandendsat20GHz.BackgroundMaterial:[e-mail][Dispersiondiagram:CSTMicrowaveStudio]2Meshsetting:ClickontheobjectsinnavigationtreeandR.Clickontheobject;thenchoosethe“Localmeshproperties”andsetitasthefollowingsuggestions:Vacuum:Meshgroup1Theautomeshoptionisdisabledforthetwoinletswhicharenotparalleltothecoordinateaxes.Otherelements:Meshgroup2Theautomeshoptionisenabled.(Inner&outerconductor,holders)Fig.3meshsettingofthemodelcomponents.BoundaryConditionsTheboundaryconditionsforxandyplanesaresetto“electric”orEt=0,whichisequivalenttoPEC,whileforthetwoboundaryconditionsinz-directionhavebeendefinedas“periodic”inordertomodelaninfiniteextentoftheproposedhelicalinnerconductorcoaxunitell.Aparameter“phase”isassignedtotheperiodicboundary,sothatthephaseshiftcanbeusedinaparametersweep,formeasuringthefrequencydispersivebehaviorofthepresentstructure.Fig.4Boundaryconditionsandphaseshiftsettingoftheonedimensionalperiodicstructure.*Auserdefinedwatchisalreadyavailableandmayserveasatemplateforbuildingcustomwatches.Theuserdefinedparametersweepwatchaddsthegroupvelocity,phasevelocityanddispersionplotsofthefirstmodetothenavigationtreeinthefolder'1DResults'.Also,[e-mail][Dispersiondiagram:CSTMicrowaveStudio]3flowandPierceImpedancecanbeseeninthefolder'1DResults'.Inparametersweepwindow,selectEdittoviewormodifythesourcecode.Fig.5theuser-definedVBAcodesoftheimportantreportsofthesimulationasdispersioncurve,phase&groupvelocityandPierceimpedance.ButIpreferredthatthefollowingmethodforsettingthedispersiondiagram.PostProcessing:Thedispersiondiagram,whichisagraphbasedon“frequency”vs.spatialphasevariationsofthepredefinedparameterof“phase”,couldobtainedbythefollowingstepbystepprocess:1)RecalltheTBPandchoosethe“2Dand3DFieldResults3DEigenmodeResult”Fig.6theoutlineofdefiningthepostprocessingsetupofdispersionplotinCSTMWS.2)Forobtainingthedispersiondataofthemodesstartonebyonefromthefirstmode,thenafterfinishingsimulationoperationexportthedatain“txt”format(availablein“Table”folderinNavigationtree)forourfuturepostprocessinginMatlabenvironment.3)EvaluateSolverSetupWheneverthe“EigenmodeSolver”isstarted,aspecificnumberofthelowestresonancefrequenciesofthestructurearecalculated.Sinceonlythefundamentalmodeisofinterest,thenumberofmodesisreducedto“1”,andtheJDMeigenmodesolverischosen,[e-mail][Dispersiondiagram:CSTMicrowaveStudio]4Fig.7EigenmodeSolversettingforcalculatingthedispersioncharacteristicsoftheproposedperiodicstructure.AftertheparametersweephasbeenselectedfromtheEigenmodeSolver'sdialog,anewsequenceisadded,andtheparameterphaseischosentobesweptfrom0to180degreesin19stepsforanequalsteps.Fig.8Parametricsweepsetupforphaseshiftparameterof“phase”inthespaceperiodicitydirection.Start:Ifyousetlowersweeplimitatzero,themachinetemporarywouldinterrupttheprocessandalertwetheparameteriszero,don’tc[e-mail][Dispersiondiagram:CSTMicrowaveStudio]5ResultsDuringtherunprocesstherealtimedispersionresultsisaccessiblefromtheTablefolder,asaplotbasedonfrequencyvs.phaseparameter,asfollowing:(a)(b)Fig.11Thedispersiondiagrambasedon(a)TBPresulttemplate,and(b)VBAuserdefined.AsshowninFig.11,allthedataarethesamebutinFig.11(a)thehorizontalaxisisthephase.ExportthedataoftheMode“1”[e-mail][Dispersiondiagram:CSTMicrowaveStudio]6Fig.12extractionoftabledispersiondataOpenviaexcelOpenanewExcelfileandopenfromityourtxtfileof“Mode1.txt”:[e-mail][Dispersiondiagram:CSTMicrowaveStudio]7Fig.13Thepreparationofthedispersiontextdatafileforproducingthecompatible*.csvfileWeshouldkeepjustthephaseandvaluecolumnandeliminateothers,theneditthetitleofthevaluecolumnas“Frequency(Mode1)”,finallysaveasaCSVfileformat,asshowninFig.13.WeshouldrepeatthesimulationforremainedmodesfrequenciesaspresentedinFig.14,andextractthefavorited