384IEEETRANSACTIONSONANTENNASANDPROPAGATION,VOL.54,NO.2,FEBRUARY2006IntegratedPlanarMultibandAntennasforPersonalCommunicationHandsetsMartaMartínez-Vázquez,OliverLitschke,MatthiasGeissler,DirkHeberling,AntonioM.Martínez-González,andDavidSánchez-Hernández,Member,IEEEAbstract—Theadventofnew,multistandardmobilephonede-vicesisanimportantchallengeforantennadesigners,astheyhavetoimplementintegratedantennaswithmultibandoperationwithinavolumethatisrapidlyshrinking.Inthepaper,researchresultsconcerningtheinputreturnloss,radiationcharacteristicsandef-ficiencyofnovelinternal,planar,multibandpatchantennasarepresented.IndexTerms—Handsetantennas,multibandantennas,smallantennas.I.INTRODUCTIONTHEconstantevolutionofthemobilephonemarketde-terminesmorestringentconstraintsforterminalantennadesign,asthesizeoftheterminalsshrinksrapidly,whilethefunctionalitiesofthehandsetsareeverincreased.Multibandop-eration,whichisnowadaysalmostacommonstandard,requirestheuseofenhancedradiatingelements.Moreover,otheraspectssuchassmallsize,weight,andintegrationhaveagreatrelevanceforthefinaldesign,whilematerialandassemblingcostsmustbekeptaslowaspossible[1].Thepreferredantennasolutiontodealwithmultistandardis-suesistheuseofradiatingpatcheswithmultipleresonancescoveringdifferentbands,whichareeasilyadaptedtotheshapeofthehandset,andcanthereforebeintegratedwithinthebackcover.Thesolutionhasanumberofadvantages:terminalde-signerscanforgetabouttheantennawhendesigningtheexternalcover,thephonebecomesmorerobustastherearenoexternalradiatingelementsthatcouldbreakoff,andtheantennascanbeproducedinamorecost-effectiveway.Ontheotherhand,theantennasmustoperateintwoormorefrequencybands,butstillbeconfinedwithinavolumethatbecomeseversmaller,andthechassisacquiresimportanceinthedesignprocess.Therefore,theup-to-datemainchallengeforthemobileantennadesigneristoachievetheminiaturizationoftheradiatingstructurewithoutlossofefficiencywhilekeepinganadequateinputreturnloss(dB)withineachbandofoperation.CoverageofGSM900,GSM1800,PCS1900andISM2450bandswerereportedin[2],[3].multibandwasachievedstartingManuscriptreceivedMarch4,2005;revisedJuly14,2005.ThisworkwassupportedinpartbytheSpanishIndustryMinistryunderprojectreferencesFIT-330200-2004-190andFIT-330210-2005-2.M.Martínez-Vázquez,O.Litschke,M.Geissler,andD.HeberlingarewithIMSTGmbH,Carl-Friedrich-Gauss-Str.2,D-47475Kamp-Lintfort,Germany.A.M.Martínez-GonzálezandD.Sánchez-HernándezarewithUniversidadPolitécnicadeCartagena,DepartamentodeTecnologíasdelaInformaciónyComunicaciones,AntiguoCuarteldeAntigones,E-30202Cartagena,Spain(e-mail:david.sanchez@upct.es,web:http://www.gimre.upct.es).DigitalObjectIdentifier10.1109/TAP.2005.863402fromadual-banddesignconsistingofaPIFAantennawithaninsertedslitatitsshortingstripedge,followingtheC-patchbasicdesign[4].Fourbandswerecoveredwithatotalvolumeof36169mmandbytwoadditionalfoldedstrips,whichmainlycontrolledthehigherresonancefortheISM2450system.Theadditionalstrips,however,werelocatedatdifferentheightlevelsandrequiredorthogonalplateorientationbetweenthem.Avolumereductiontoequalthatreportedin[5]wasachievedin[6]forbothquad-andafive-banddesigns.ThereductionwaspossiblebyusingastubextendingfromthefoldedpatchtoenlargeGSM900andGSM1800bandwidthsandalsobyinsertinganadditionalfoldeddirect-feedmetalstrip,bothaddedtothebasicantennareportedin[5],whichwasusedasastartin...
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