4G手机天线

DesignofanInternalMulti-bandLoopAntennaforMultipleMobileHandsetOperationsChuandiDai1,DuolongWu1,andYanjieWu11GuangdongUniversityofTechnology,Guangzhou,Guangdong,510006,P.RChinaEmail:[e-mail],[e-mail],[e-mail]—Acompactinternalmulti-bandfoldedloopantennaforGSM850/900/DCS/PCS/UMTS/LTE2300/2500/WLAN2.4GHz/WiMAX2.5GHzmultiplemobileoperationsisproposed.ThewholeantennastructureproposedinthispaperconsistsofasinglefoldedmeanderlooptrackandaT-shapeback-couplingelement.Thesizeofthetotalstructureis120×60×6.5mm3,meanwhilethearealeftforthelooptrackisonly60×15×6.5mm3.Thecompactstructuremakesitverysuitableforsmallmobilephoneapplications.ThedesignandoptimizingoftheperformanceoftheproposedantennaareperformedbyusingthesimulatorsoftwareHFSS.Anactualmodelhasbeenprototypedfortesting.Measurementresultsandelectromagneticsimulationonesareingoodagreement,thusindicatingthattheproposedantennacanmeettheactualdemands.IndexTerms—Handsetantenna,foldedloopantenna,mobilephoneantenna,multi-bandantenna,LTE,WLAN,WiMAX.I.INTRODUCTIONWiththerapiddevelopmentofwirelesscommunicationtechnologies,especiallysmartphones’ever-changingwitheachpassingday,mobileterminalshavebeenincreasinglygrowingtowardsminiaturized,ultra-thin,highlyintegrat-ed,multi-functionandhigh-performance.Thereforethedemandsofdesigningnovelcompactmulti-bandantennastomeetthegrowingrequirementsofintegratingmorewirelessservicesinthenarrowspaceofthemobileterminalsareincreasedcontinuously.Inordertomeettheactualneeds,inrecentyears,avarietyofnovelmobilephoneantennashavebeendevelopedandappliedconstantly.Loopantennawhichisakindofself-balanceantennacanoperateanunbalanced0.5λmodeand1.5λmodeaswellasabalanced1λmode[1].Thereforeuptothreeresonancemodescanbegeneratedinasinglecontinuouslooptrackduetotheseuniquemultimodefeatures[1],[11].Inaddition,withtheaidofappropriatetuningtechnology,loopantennacanevenexciteanextra2λwavelengthworkmode[1].Theseadvantagesofmulti-modeandmulti-resonancemakeloopantennaveryfacilitatedtocoverthemulti-bandmobilecommunicationoperations.Meanwhile,thesurfacecurrentpathsexcitedbythelooppatternareinaclosedform,whichmakesthecouplingbetweentheantennatrackandthesystemgroundmuchsmallerthantheconventionaltypesofantennas,suchasPIFAandfoldedmonopole[8].Henceloopantennaisverysuitableforthecomplexinterferenceanddissipationenvironment,justasthemobilephones’workingenvironment[12].Theseallmakeloopantennaveryattractivefortheresearchandapplicationofnewmobileterminalantennadesigns.Toovercometheshortcomingsoftheloopantennawithahighresonantimpedancesoastomakeitsuitableformobilephones’50Ωfeedingscheme,recently,varietiesofdifferenttuningtechniqueshavebeencontinuouslystudiedanddeveloped.Areconfigurableloopantennaisintroducedin[2],[3].ByusingthematchingbridgeorP-I-Ndiodetocontroltheantenna’scurrentflowing,therebytheresonancecharacteristicoftheloopantennaiscontrolled.Thattheloopantennaiscouplingmotivatedbythefeedingmonopoleandanextraparasiticelementisaddedtoformtwobroadbandresonancesismentionedin[4],[5].Theuseofback-couplingelementconnectedtothemicrostriplinetofeedthelooppathabovethePCBisproposedin[6],[7],[8].Mostoften,addingacentraltuningpadorapassivematchingnetworktoimprovetheresonanceperformanceofthelooppatterncanyetberegardedasaneffectiveapproach,justas[1],[2],[3],[9],and[10]proposed.Inthispaper,thedesignofacompactinternalfoldedloopantennaformultiplemobilecommunicationsystemshasbeenpresented.ThewholestructureconsistsofacontinuousmeanderlineshapefoldedloopradiatingpathandaT-shapecouplingelementonthebackplaneofthePCB.Thecouplingunitisconnectedtothe50Ωfeedingmicrostripline,excitingthelooptrackabovethepositiveplaneofthePCBbyelectromagneticcoupling.Theproposedantennastructuregeneratesthreebroadbandwidth(797-1243,1650-2165,and2230-2847MHz)foraVSWR=3:1,thusbeingabletocoverGSM850/900(LowBand:824-960MHz),DCS/PCS/UMTS(MiddleBand:1710-2170MHz)andLTE2300/2500/WLAN2.4-GHz/WiMAX2.5GHz(HighBand:2305-2690MHz)ope-rations,respectively.Theoccupiedspaceofthewholeantennastructuremeasures120×60×6.5mm3,whereasthespaceforloopradiatingstructureisonlyabout60×15×6.5mm3.Compactstructureandlowheightmakethedesignveryeasytomeetthenarrowspaceconstraintsofthemobile978-1-4673-2141-9/13/$31.00©2013IEEEterminals.Theproposedantennahasbeensimulated,prototypedandtested.Obtainedgoodagreementofthesimulatedandmeasuredresultsindicatesthattheproposedloopantennacanworkwellaspredicated.II.ANTENNADESIGNFig.1showsthegeometryoftheproposedantennaforthemultipleoperationsinthemobilehandset.Theentiresystemhasaverysymmetricalform,whereastheantennastructurecomprisesaloopradiatingpatternandaT-shapecouplingelement.Theloopradiatingpathwhichisaclosedmetalpatchismountedona6.5mmhighfoamdielectricsubstratewitharelativepermittivityof1.07andconnectedtothesystemmonolayergroundplanebytwoshortingpoints.ThePCBwithathicknessof0.8mmandanareaof120×60mm2ismadeupofFR-4,ofwhichtherelativepermittivityis4.4andlosstangentis0.02.Thelooppatternhasameanderlinestructureandisfoldedintoseveralplanarregionssoastoincreaseitselectricallength