On the efficiency and gain of antennas天线地效率与增益.pdf

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1、OntheefficiencyandgainofantennasKarlsson,AndersPublished:2006-01-01LinktopublicationCitationforpublishedversion(APA):Karlsson,A.(2006).Ontheefficiencyandgainofantennas.(TechnicalReportLUTEDX/(TEAT-7144)/1-11/(2006);Vol.TEAT-7144).[Publisherinformationmissing].GeneralrightsCopyrightandmoralrig

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accesstotheworkimmediatelyandinvestigateyourclaim.Downloaddate:04.Sep.2018CODEN:LUTEDX/(TEAT-7144)/1-11/(2006)OntheefficiencyandgainofantennasAndersKarlssonElectromagneticTheoryDepartmentofElectricalandInformationTechnologyLundUniversitySwedenA

5、ndersKarlssonanders.karlsson@es.lth.seDepartmentofElectricalandInformationTechnologyElectromagneticTheoryLundUniversityP.O.Box118SE-22100LundSwedenEditor:GerhardKristenssoncAndersKarlsson,Lund,February23,20061AbstractThefundamentallimitsofthegainandeciencyofanantennaareexplored.Theantennaisc

6、onnedinasphereandallofthecurrentsareassumedtoruninamaterialwithaconductivitythatisafunctionoftheradialcoordinate.Theanalysisisbasedontheexpansionoftheelectromagneticeldsintermsofvectorsphericalharmonics.Explicitexpressionsforthelimitsofgainandeciencyarederivedfordierenttypesofantennas.1In

7、troductionSmallantennassuerfromphysicallimitationsthatreducetheirbandwidthandincreasereturnlossesandohmiclosses.Thelimitationsarecausedbythelargereactiveelectromagneticeldsinthevicinityoftheantenna.Thereactiveeldsarerelatedtothereactivecur