外文翻译新的双频双极化开槽微带天线的设计方法.docx
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外文翻译新的双频双极化开槽微带天线的设计方法.docx
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外文翻译新的双频双极化开槽微带天线的设计方法
ANovelMethodforDesigningDual-FrequencySlotPatchAntennaswithTwoPolarizations
WUDi1,OHISHIBASHIHidekazu2,SEOKazuyuki2,INAGAKINaoki3
(1.DepartmentofCommunicationEngineering,ShanghaiUniversity,Shanghai200072,China;
2.KojimaR&DCenter,KojimaPressIndustrialCoLtd,Aichi470—0207,Japan;
3.NagoyaInstituteofTechnology,Nagoya466—8555,Japan)
Abstract:
Thispaperpresentsanewmethodfordesigningadual-frequencypatchantennawithcircularandlinearpolarizations.Dual-frequencyoperationsarebehavedbyetchingtwonarrowslotsclosetotheradiatingedgesofarectangularpatch.Thecircularpolarizationatthelowerresonantfrequencyofthedual-frequencyantennacanbeachievedbysettingaperturbationsegmentatanappropriatelocationinthepatchelement,andplacingthefeedpointonthediagonalaxis.Severalexperimentalresultsofadesignedantennashowthegoodcharacteristicsforcircularandlinearpolarizationsatbothresonantfrequencies.
CLCnumber:
TN821.1Documentcode:
A
Keywords:
dual-frequency;slotpatchantennas;linearpolarization;circularpolarization
Inradarandcommunicationsystems,dual-frequencyoperationsareoftenrequired.Specially,inmodernmobileglobalpositionsystem(GPS),itwillbedesirablethatoneoftwofrequenciesisthecircularpolarization.Planarantennahasbeeninvestigatedformulti-frequencyverywellsinceitisadvantageousinlowcost,lowweightandconformability.Earlydual-frequencyplanarantennaismultilayeredstacked-patchstructure,andtheradiatingelementisusedtobecircular[1],annular[2],rectangular[3]andtriangularpatches[4].Recently,adual-frequencyantennaisintroducedinwhichthestructureisdinglelayerpatchwithtwoslotsclosetotheradiatingedges,andgoodperformancesofsimultaneousimpedancematchingandgainaredemonstratedforbothresonantfrequencies.However,alltheconventionalinvestigationsareonlyforthecaseinwhichtheantennapolarizationislinear,whilethedual-frequencyantennawithcircularpolarizationhasnotbeentouchedyet.
Inthispaper,wepresentadesignmethodofadual-frequencyantennawithcircularandlinearpolarizationsbasedontheconventionalinvestigationforthedual-frequencylinearpolarizationantenna[5~7],Tworesonantfrequenciesaredeterminedbyadjustingthesizeofthepatchelementandtheslot,aswellasthelocationoftheslotintheelement.Thekeytoobtainacircularpolarizationforanantennaistosatisfytheconditionforexcitingcircularpolarization,ie,thecircularpolarizationcanbeexcitedbysettingtheperturbationsegment⊿,atanappropriatelocationinthepatchelement,andbyplacingthefeedpointonthediagonalaxis.Wehaveexperimentallyobtainedthecircularandthelinearpolarizationsatbothlowerandupperfrequencies,andsomeexperimentalresultswillbedemonstratedonthereflectionlossatinputportandtheradiationpatternoftheantenna.
1Configurationofconventionaldual-frequencypatchantenna
Figure1showsaconfigurationofaconventionaldual-frequencyantennawithlinearpolarization.Tworesonantfrequenciesarebehavedbyetchingtwoslotscloseandparalleltotheradiatingedges,andthelowerresonantfrequencyisdeterminedbytheoutlinesizeofthepatchelement,whiletheupperresonantfrequencyisdeterminedbythesizeandthepositionofthetwoslotsinthepatchelement.Becausetheslotsarecloselylocatedtotheradiatingedges,aminorperturbationoftheTM10modecanbeexpected.AsforunperturbedTM30mode,sincetheslotsarelocatedwherethecurrentshallbesignificant,thecurrentwillbestronglymodified,andaperturbedTM30radiationpatternsimilartotheTM10modecanbeobtained.
Ourobjectinthisinvestigationistoobtainadual-frequencyantennawithbothpolarizationinwhichthelowerfrequencyiswithacircularpolarizationandtheupperfrequencyiswithalinearpolarization.ForasquarepatchantennawithareaofSfedbyoneport,awaytoexciteacircularpolarizationistoextendthelengthoftwoparallelsubtendsofthepatchelementinordertosetaperturbationsegment⊿s,andplacethefeedingpointonthediagonalaxis.Whenanappropriateperturbationisselected,acircularpolarizationwithagoodaxialratiocanbeobtained.
Fig1Configurationofconventionaldual-frequencyantenna
2 Designingfordual-frequencyslotpatchantennaswithtwopolarizations
Inaconventionalinvestigationfordual-frequencywithlinearpolarization[5~7],toensurea
goodradiationefficiencyatbothfrequencies,theaspectratiobetweenthetwosidesofthepatchis
takenintherange
(1)
andthelowerfrequencyisdeterminedby
(2)
wherecisthevelocityoflightinfreespace,
istheeffectivepermittivitygivenby
(3)
and
(4)
(5)
here
(6)
andtheupperfrequencyisdeterminedby
(7)
Inaboveexpression,theparametersofW,L,t,w,d,larereferredtoFig2,andthe
isthedielectricconstantofthesubstrate.However,inthisstudy,inordertoobtainacircularpolarizationatthelowerresonantfrequency,theaspectratiooftheoutlinesizeofthepatchwillbechangedsothatthementionedformulasabovewillnotbecompletelysatisfied.
Fig2Configurationofdual-frequency
Wepresentadesignmethodfordual-frequencyslotpatchantennawithtwopolarizationasfollows.
Step1Designasquarepatchantennawiththedesirablelowerfrequencyf10byusingaconventionalmethod.
Step2Etchtwoslotscloseandparalleltotheradiatingtobehavethedual-frequenciesoperationbyusingEq(7).Howeverthelowerresonantfrequencyf10willchange,sincetheslotsmodifythecurrentdistributionoftheTM10.
Step3Adjustthesizeoftheantennaelementtoobtainthedesiredlowerresonantfrequency.
Step4Adjustthelengthandthewidthoftheslotstoobtaintheupperresonantfrequencyf30.
Step5Setperturbationsegmentandplacethefeedpointonthediagonalaxisoftheantennatoobtainthecircularpolarizationatthelowerresonantfrequencyf10.
3Experimentalresultsanddiscussion
Weexperimentallydesignedadual-frequencypatchantennawithtwopolarizations.Figure2showstheconfigurationoftheantenna,andthespecificationsarelistedinTable1.Inthisconfigurationoftheantenna,weextendedtheLedgeofthepatchantennatosettheperturbationsegment,andplacedthefeedpointonthediagonalaxistoachievethecircularpolarization.
Table1Specificationsofadual-frequencypatchantennawithtwopolarization
GPS
VICS
Frequency/GHz
1.575
2.5
Polarization
Circular
Linear
Returnloss
-15
-15
Gain
3dBic
5dBi
Figure3showsameasuredreflectionlossofadesigneddual-frequencyantennafedby50Ώcoaxialprobe.Fromthisfigure,itcanbeobservedthattworesonantfrequenciesareachievesatdesiredfrequencies1.575GHzand2.50GHz,whichwillbeemployedtomobileglobalpositionsystem(GPS)andvehicleinformation&communicationsystem(VICS),andagoodsimultaneousimpedancematchingwasobtainedforreflectionlossvalues-17dBat1.575GHzand-27dBat2.5GHz.
Fig3Frequencycharacteristicsofreflectionloss
Figure4showstheaxialratiovariationwiththefrequencyforthisdesignedantenna.Itisseenthatthebestvalueoftheaxialratioisabout1dBat1.575GHz.
Fig4Frequencycharacteristicsofaxialratio
Figure5showsthemeasuredimpedancecharacteristicsoftheantennaincorrespondencewithFig3.Itdemonstratedthataperturbationissetforcircularpolarizationatlowerfrequency1.575GHz.
Fig5Frequencycharacteristicsofinputimpedance
Figure6showstheradiationpatternofthecircularpolarizationofthedesignedantennaatthelowerresonantfrequency1.575GHz.Inthisfigure,weusedtheunit[dBic]forgain,whichcanbecalculatedasfollows
where,Gmax[dBi]denotesthemeasuredmaximumgainin[dBi],ARisthemeasuredaxialratio.Againof3.7[dBic]wasfoundforpatchantennawithcircularpolarizationat1.575GHz.
Fig6Radiationpatternofcircularpolarization
Finally,theradiationpatternofthelinearpolarizationattheupperfrequency2.5GHzisshowninFig7.ThisistheperturbedTM30mode,however,becausethetwoslotsexistinthepatch,theshapeoftheradiationpatternoftheperturbedTM30modebecomessimilartothatofTM10mode.Againof5[dBi]wasobtainedforpatchantennawithlinearpolarizationat2.5GHz.
Fig7Radiationpatternoflinearpolarization
4Concludingremarks
Anoveldesignmethodforadual-frequencypatchantennawithbothcircularandlinearpolarizationispresentedinthispaper.Tworesonantfrequenciesarebehavedbyetchingtwoslotsclosetotheradiatingedgesintherectangularpatch,andthecircularpolarizationatthelowerresonantfrequencyisachievedbysettingaperturbationsegmentinthepatchelement,andbyplacingthefeedpointonthediagonalaxis.Adual-frequencyantennawithbothpolarizations,whichwillbeusedtoGPSandVICSformobilecommunication,isdesignedbyusingpresentedmethod.Asformeasuredresult,itdemonstratedthatthedesignedantennahastworesonantfrequency,inwhichoneisacircularpolarizationwithanaxialratio1[dB]andgain3.7[dBic]atlowerfrequency,andtheotherisalinearpolarizationwith5[dBi]attheupperfrequency.
References:
[1] LongSA,WaltonMD.Adual-frequencystackedcircular-discantenna[J].IEEETransAntennasPropagat,1979,AP27:
270273.
[2] DaheleJS,LeeKF,WongDP.Dualfrequencytackedannular-ringmicrostripantenna[J].IEEETrans,1987,AP35(11):
12811285.
[3] WangJ,FralichR,WuC,etal.Multifunctionalapertureco
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