RFID标签天线的文献语录.docx

RFID标签天线的文献语录.docx

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RFID标签天线的文献语录

RFID标签天线的文献语录

《AnewresonantfrequencytunableRFIDtagantennadesign.pdf》

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《ANovelBroadbandUHFRFIDTagAntennaMountableonMetallicSurface.pdf》

Tosomeextents,thetagantennaisconsideredasthemostimportantpartwhichdirectlyaffectsthecommunicationbetweenthereaderandtaginanRFIDsystem.However,itishardtodesignatagantennaforpassiveUHFRFIDapplicationsbecauseoftwomainobstacles.First,amicrochiphasahighqualityfactorbecauseofitssmallresistanceandlargecapacitancereactanceatitsterminals,whichmakesitnoteasytoattaintheconjugatematchbetweenthetagantennaandthemicrochiportoachieveawidebandcharacteristic.Secondly,theperformanceofatagantennavarieswhenitismountedondifferentobjects.Especially,metallicobjectswhichareusuallytaggedinRFIDapplicationsseriouslydegradetheterminalimpedancematching,bandwidth,radiationefficiencyandreadablerangeofthetagantenna[2].

Theshortingstripsareusedtoachievemorebalancedcurrentdistributionsonthepatches.

Themaindirectionofelectricfieldonthepatchesisalongwiththex-axisandthecurrentsalongwithy-axisaresmaller,whichcontributestoagoodcross-polarizationperformance.

TheconjugatematchbetweentheantennaandthemicrochipcanbetunedbyadjustingtheperimeterandthelinewidthoftheloopoftheT-matchingnetwork.Anelectricalcouplingisgeneratedaroundthegapbetweenthetwopatches,whichincreasesthebandwidthoftheantenna.Thebandwidthoftheproposedantennacanbecontrolledinacertaindegreebyalternatingthewidthofthisgaporthelinewidthofthetwoshortingstrips.Eventually,theproposedantennaisoptimizedtohavetheconjugatematchbetweenitselfandthemicrochip.Also,somespacesamongthepatchesandtheT-matchingnetworkarereservedfortuningtheT-matchingnetworktogetanimpedancematchingwithoutmodificationsofthetwopatchesinthecaseofothermicrochipischosen.

Thehalfpowerbandwidth（returnloss<-3dB）

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《AnovelsmallantennaforpassiveRFIDtransponder.pdf》

Theseearlystudiesshowthatsmallantennasareconstrainedintheirbehaviourbyafundamentallimit:

thesmallerthemaximumdimensionoftheantenna,thehigherisitsQ,orequivalently,thenarrowerisitsbandwidth.……Accordingly,theartofantennaminiaturisationisalwaysanartofcompromiseamongsize,bandwidth,andefficiency（gain）.

ImpedancematchingbetweentransponderASICandantennaiscriticalonoverallRFIDsystemperformance.Namelythemismatchverystronglyaffectareadrange–amaximumoperatingdistancebetweeninterrogatorandtransponder.Becausethepowerradiatedbyinterrogatorisratherlimitedduetocertainsafetyregulationsandotherlegislation.AndpassiveRFIDtransponderextractsitsoperatingpowerbyrectifyinginterrogationsignaldeliveredbytheantenna.

RectifiercircuitisapartofASICandcomprisesdiodes（suchasSchottkydiodes）andcapacitors,resultinginthecomplexinputimpedancewithsubstantialcapacitivereactance.TypicallytheimpedanceofASICcomestoafewortensofactiveOhmsandafewhundredsofreactive（capacitive）Ohms.Thustheratioofthereactancetotheresistanceisveryhigh.

Oneconventionalmatchingtechniqueinsuchasituationisanimplementationofadditionalseparatematchingcircuitbasedoninductors.However,aconventionalwayisnowproblematicbecauseitunacceptablyincreasesproductioncosts.Moreover,aseparatematchingcircuitcausesextralossesthateventuallyalsostronglyreducesystemperformance.Consequently,theantennaimpedanceshouldbematcheddirectlywithASICofthetransponder.

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《AnalysisanddesignofaUHFRFIDtagantennawithaSplitRingResonator.pdf》

ForUHFranges,thedipole-liketagswhicharemostlyusedinmanyapplicationsaretoobigtoattachtoasmallobject.Sotherearelotsofstudiesaboutsmalltagantennaswithmeandertypeline.Howevermostofthetagsaresufferfromanarrowbandwidth,lowgain,lowradiationefficiency,andhardcontrolofthetagantennaimpedance.

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《AntennadesignforUHFRFIDtags:

areviewandapracticalapplication.pdf》至少读5遍

Apassiveback-scatteredRFIDsystemoperatesinthefollowingway.Abasestation（reader）transmitsamodulatedsignalwithperiodsofunmodulatedcarrier,whichisreceivedbythetagantenna.TheRFvoltagedevelopedonantennaterminalsduringunmodulatedperiodisconvertedtodc.Thisvoltagepowersupthechip,whichsendsbacktheinformationby