外文翻译参考.docx

外文翻译参考.docx

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外文翻译参考

外文翻译

毕业设计题目：

GPS抗干扰天线技术—多频带高增益微带天线单元的仿真与设计

原文1：

H-MRTDsimulationofdual-frequencyminiaturepatchantenna

译文1：

双频微型贴片天线的H-MRTD模拟

原文2：

ANovelMethodforDesigningDual-FrequencySlotPatchAntennaswithTwoPolarizations

译文2：

新的双频双极化开槽微带天线的设计方法

H-MRTDsimulationofdual-frequencyminiaturepatchantenna

YUWen-ge1,2,ZHONGXian-xin1,LIXiao-yi1,CHENShuai1

（1.TheKeyLabforOptoelectronicTechnology&SystemsofMinistryofEducation,

ChongqingUniversity,Chongqing400044,China;

2.BasicLogisticalEngineeringUniversity,Chongqing400016,China）

Abstract:

AnovelMEMSdual-bandpatchantennaisdesignedusingslot-loadedandshort-circuitedsize-reductiontechniques.Bycontrollingtheshort-planewidth,f10andf30,tworesonantfrequencies,canbesignificantlyreducedandthefrequencyradio（f30/f10）istunableintherange1.7～2.3.TheHaar-Wavelet-Basedmultiresolutiontimedomain（H-MRTD）isusedformodelingandanalyzingtheantennaforthefirsttime.Inaddition,themathematicalformulaeareextendedtoaninhomogenousmedia.Numericalsimulationresultsarecomparedtothoseachievedusingtheconventional3-Dfinite-differencetime-domain（FDTD）methodandmeasured.Ithasbeendemonstratedthat,withthistechnique,spacediscretizationwithonlyafewcellsperwavelengthgivesaccurateresults,leadingtoareductionofbothmemoryrequirementsandcomputationtime.

Keywords:

dual-frequencyantenna;H-MRTDmethod;FDTDmethod;MEMS;UPMLabsorbingboundaryconditions

1　Introduction1

　　Recently,patchantennaresearchhasfocusedonreducingthesizeofthepatch,whichisimportantinmanycommercialandmilitaryapplications.IthasbeenshownthattheresonantfrequencyofamicrostripantennacanbesignificantlyreducedbyintroducingaShort-circuitedplaneorapartlyshort-circuitedplanewheretheelectricfieldoftheresonantmodeiszero[1-3],orashort-pinnearthefeedprobe[4].Usingtwostackedshort-circuitedpatches,dual-frequencyoperationhasbeenobtained[5].However,theuseofastackedgeometryleadstoincreasesinthethicknessandcomplexityofthepatch.Inthispaper,wedemonstratethatbyshort-circuitingthezeropotentialplaneofaslottedpatchexcitedwithadominantmode（TM10）,theresonantfrequencies,f10andf30,ofthetwooperatingmodescanbeapproximatelyhalvedandcanevenbesignificantlyreducedbydecreasingtheshorted-planewidth.Thisindicatesthatalargereductioninantennasizecanbeobtainedbyusingtheproposeddesign,ascomparedtothatofaregularslot-loadedpatch.

Thefinite-differencetime-domain（FDTD）method[6]iswidelyusedforsolvingproblemsrelatedtoelectromagnetism.However,therestillexistmanyrestrictivefactors,suchasmemoryshortageandCPUtime,etc.wefirstadoptedthemethodoftheHaar-Wavelet-BasedMultiresolutionTimeDomain（H-MRTD）[7-9]withcompactlysupportedscalingfunctionforafullthree-dimensional（3-D）wavetoYee’sstaggeredcelltoanalyzeandsimulatethedualfrequencymicrostripantenna.ThemajoradvantageoftheMRTDalgorithmsistheircapabilitytodevelopreal-timetimeandspaceadaptivegridsthroughtheefficientthresholdingofthewaveletcoefficients.Usingthistechnique,spacediscretizationwithonlyafewcellsperwavelengthgivesaccurateresults,leadingtoareductionofbothmemoryrequirementandcomputationtime.Associatedwithpracticalmodel,auniaxialperfectlymatchedlayer（UPML）absorbingboundaryconditions[10]wasdeveloped,athree-dimensionalformulationofthediscretedifferenceequationsarisingfromtheMaxwell’ssystemisfirstextendedtoaninhomogenousmedium,itisappliedtotheanalysisofdual-frequencyminiaturepatchantenna.

2　Dual-frequencyslot-loadedpatchantenna

2.1　Designofslot-loadedpatchantenna

Thelayoutoftheslot-loadedpatchantennadesignedinthispaperisshowninFig.1.AsingleslotwithdimensionsL×Wiscutinarectangularpatchwithdimensionsa×bwithashort-circuitedplaneofwidthplacedatitsotherside.Theparametersoftheantennaarea=38mm,b=25mm,L=36mm,W=1mm,d=2mm,h=3mm,r=1mm,respectively.OwingtobeingcompatiblewithstandardICtechnology,andpronetointegrationwithothercomponents,siliconwafer（εr=11.7）wasselectedasalayerofmicrostripsubstrate.Betweenthegroundplateandthewaferthereisalayeroffoam（εr=1.07）,whichcouldsuppresssurfacewaveinducedinthewafersubstrate,asaresult,theefficiencyandthebandwidthoftheantennawereincreased,andtheradiationpatternimproved.

Fig.1Geometryofdual-bandslot-loadedmicrostripantenna

2.2　Measuredresults

Theparametersoftheslotantennaareselectedasabovementioned.ThemeasurementscarriedoutonanAgilent8720Cvectornetworkanalyzer.Itisthenfoundthat,bycontrollingtheshorted-planewidth,boththeTM10andTM30modesarestronglyperturbed.Fig.2showstypicalresultsofthemeasuredreturnlossforthecaseswiths/a=1,0.25,and0.1.RegardingtheresultsshowninFig.2,itcanbeseenthattheperturbedTM10andTM30modesareexcitedwithgoodimpedancematching.However,whens/a<0.1,therenofeedpointcanbefoundforexcitingthetwofrequencieswithgoodimpedancematching.Thisindicatesthattherearelimitationstothepresentdual-banddesign.Itcanbeseenthattheobtainedfrequencyratio（f30/f10）ofthetwofrequenciesforpresentdesignvariesintherange1.7～2.3.Ontheotherhand,forthecases/a=0.1,showninFig.2,thefrequencyf10occurringat1.562GHzis～0.31timesthat（5.038GHz）foraregularhalf-wavelengthpatchwiththesamepatchsize.Inotherwords,thesizeofthedesignedantennainthispaperismuchsmallerthanregularhalf-wavelengthpatchantenna.

Fig.2Measuredreturnlossfordifferentshorted-planewidths

3　3-DH-MRTDalgorithm

3.1　Numericalformulationsofthe3-DH-MRTDmethod

Maxwell’scurlequationsinanisotropicmedium:

（1）

whereεispermittivity,μispermeability,σiselectricconductivity.Eachfieldcomponentisexpandedintoscalingfunctions:

（2）

Andwavelets:

（3）

Where,

and

.

Expansionandtestingisperformedforeachspatialcoordinates={x,y,z}withcorrespondingdiscretizationindicesu={k,l,m},aswellasfortimewithrectangularpulsehn（t）.Incompactnotations,thex-directedelectricfieldcomponentinthestaggeredYee’sgridofsizeΔx,Δy,Δzisrepresentedas

（4）

wherex=kΔx,y=lΔy,z=mΔz,t=nΔt.

Thesummationoverξηζincludeseighttermsstemmingfromallthepermutationsofscalingfunctionsandwavelets:

.TherepresentationoftheotherfieldcomponentsiseasilyderivedthroughpermutationoftheindicesandfollowsthesameruleasforstandardFDTDscheme.InsertingtheaboveexpressionsintothedifferenceequationandperformingaGalerkintestprocedure[12]leadstothefollowingexpressionsfortheelectricfieldwithineachcell{k,l,m}:

（5）

where{0,1,2,3}denotes,respectively,{u,u+1/2,u-1/2,u+1}foreachu={k,l,m,n}.Informula（5）,therearethreedifferentΕxvalueswithinonetimestep,thisbringsaboutinconvenienceforprogramdesign.Inordertoavoidtheshortcoming,wecanadoptapproximationasfollows:

（6）

Similarexpressionsareobtainedfortheotherfieldcomponents.

3.2　Absorbingboundarycondition

Thefieldcomputationdomainmustbelimitedinsizebecausethecomputercannotstoreanunlimitedamountofdata.Thecomputationdomainmustbelargeenoughtoenclosethestructureofinterest.Inthispaper,weadopteduniaxialperfectlymatchedlayer（UPML）absorbingboundaryconditions.Consideronedimensionwaveequationpropagatedalong+zdirection:

，（7）

whereσ′=σ/ε,visthephasevelocityintheconcernedvolume.Becausetheconductivityσisprojectedincomputationdomain,itwillresultinnumericdispersionifweusedirectlydiscreteapproximationforformula（7）,Let

，then

itsfinitedifferenceformis

（9）

Thedifferenceformofformula（7）is

where

aretheMRTDcoefficients.

TheUPMLmaterialparametersarechosentobe

fortheinnercomputationregion.ThemaximumvalueofσattheendoftheUPMLregionischosentobe

where⊿isthecelldimensionperpendiculartotheUMPLinterfacetotheregularregion.TheUMPLregionisbackedbyaperfectelectricconductorwallimplementedusingthemirrorprinciple.

4　Computedresults

　　Inmicrowavecircuitanalysis,Gaussimpulseisgenerallyselectedasanexcitationforsmoothnessintimedomainandeasyspectrumwidthsetting.ThewidthofGausspulseisT=18ps,assumethatthetimedelayt0=3T=54ps,TheresponsevalueofthefrequencydomaincanbecalculatedbyFouriertransformingthetimedomainvalue.

ThecirclewavelossesoftheantennacomputedareshowninFig.3andFig.4fors/a=1ands/a=0.25,respectively.Thecomputedcurvesbasedcomputationdomain100×120×60andΔx=Δy=0.15mm,Δz=0.015mm.FromFig.3andFig.4,wecanfindthecomputedresultsbyusingFDTDmethod,andH-MRTDmethodareingoodagreementwithmeasuredresults.ThedriftsbetweenthemensuredvalueandthecomputedvaluebyusingFDTDandH-MRTDareabout2%and2.5%infine-grid,respectively.Thelengthofthenovelpatchantennaislessthan1/7wavelength,theefficiencythisnovelantennaarriveat70%.Thecharacteristicparameterssuchaseffectivedielectricconstant,thecharacteristicimpedanceinspectrumdomaincouldbeworkedoutbyFouriertransform.

Fig.3Computedreturnlossfors/a=1

Fig.4Computedreturnlossfors/a=0.25

ThesesimulationswereperformedbyXFDTD,theinformationaboutdual-frequencyantennasimulati