RFID技术发展现状外文文献翻译文档格式.docx

RFID技术发展现状外文文献翻译文档格式.docx

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英文原文及中文译文）

文献出处：

CataT.CurrentRFIDTechnology[J].InternationalJournalofTechnologyMarketing,2012,3（3），12-21.

英文原文

CurrentRFIDTechnology

CataTed

ThissectiondescribesoutofwhichpartsRFIDtagsconsistof,howtheyworkinprinciple,andwhattypesoftagsdoexist.Itfocusesonhowtagsarepoweredandwhatfrequencyrangesisused.Thesectionconcludesbycoveringafewimportantstandards.

RFIDtransponders（tags）consistingeneralof:

Microchip,Antenna,Case,Battery（foractivetagsonly）ThesizeofthechipdependsmostlyontheAntenna.Itssizeandformisdependentonthefrequencythetagisusing.

Thesizeofatagalsodependsonitsareaofuse.Itcanrangefromlessthanamillimeterforimplantstothesizeofabookincontainerlogistic.Inadditiontothemicrochip,sometagsalsohaverewritablememoryattachedwherethetagcanstoreupdatesbetweenreadingcyclesornewdatalikeserialnumbers.

ARFIDtagisshowninfigure1.Theantennaisclearlyvisible.Assaidbeforetheantennahasthelargestimpactofthesizeofthetag.Themicrochipisvisibleinthecenterofthetag,andsincethisisapassivetagitdoesnothaveaninternalpowersource.

InprincipleanRFIDtagworksasfollows:

thereadingunitgeneratesanelectro-magneticfieldwhichinducesacurrentintothetag'

santenna.Thecurrentisusedtopowerthechip.Inpassivetagsthecurrentalsochargesacondenserwhichassuresuninterruptedpowerforthechip.Inactivetagsabatteryreplacesthecondenser.Thedifferencebetweenactiveandpassivetagsisexplainedshortly.Onceactivatedthetagreceivescommandsfromthereadingunitandrepliesbysendingitsserialnumberortherequestedinformation.Ingeneralthetagdoesnothaveenoughenergytocreateitsownelectro-magneticfield,insteaditusesbackscatteringtomodulate（reflect/absorb）thefieldsentbythereadingunit.Becausemostfluidsabsorbelectro-magneticfieldsandmostmetalreflectthosefieldsthereadingoftagsinpresenceofthosematerialsiscomplicated.

Duringareadingcycle,thereaderhastocontinuouslypowerthetag.Thecreatedfieldiscalledcontinuouswave,andbecausethestrengthofthefielddecreaseswiththesquareofthedistancethereadershavetousearatherlargepower.Thatfieldoverpowersanyresponseatagcouldgive,sothereforetagsreplyonside-channelswhicharelocateddirectlybelowandabovethefrequencyofthecontinuouswave.

1EnergySources

Wedistinguish3typesofRFIDtagsinrelationtopowerorenergy:

Passive,Semi-passive,ActivePassivetagsdonothaveaninternalpowersource,andtheythereforerelyonthepowerinducedbythereader.Thismeansthatthereaderhastokeepupitsfielduntilthetransactioniscompleted.Becauseofthelackofabattery,thesetagsarethesmallestandcheapesttagsavailable;

howeveritalsorestrictsitsreadingrangetoarangebetween2mmandafewmeters.Asanaddedbenefitthosetagsarealsosuitabletobeproducedbyprinting.Furthermoretheirlifespanisunlimitedsincetheydonotdependonaninternalpowersource.

Thesecondtypeoftagsissemi-passivetags.Thosetagshaveaninternalpowersourcethatkeepsthemicrochippoweredatalltimes.Therearemanyadvantages:

Becausethechipisalwayspowereditcanrespondfastertorequests,thereforeincreasingthenumberoftagsthatcanbequeriedpersecondwhichisimportanttosomeapplications.Furthermore,sincetheantennaisnotrequiredforcollectingpoweritcanbeoptimizedforbackscatteringandthereforeincreasingthereadingrange.Andlastbutnotleast,sincethetagdoesnotuseanyenergyfromthefieldthebackscatteredsignalisstronger,increasingtherangeevenfurther.Becauseofthelasttworeasons,asemi-activetaghasusuallyarangelargerthanapassivetag.

Thethirdtypeoftagsisactivetags.Likesemi-activetagstheycontainaninternalpowersourcebuttheyusetheenergysuppliedforboth,topowerthemicrochipandtogenerateasignalontheantenna.Activetagsthatsendsignalswithoutbeingqueriedarecalledbeacons.Anactivetag'

srangecanbetensofmeters,makingitidealforlocatingobjectsorservingaslandmarkpoints.Thelifetimeisupto5years.

2.FrequencyBands

RFIDtagsfallintothreeregionsinrespecttofrequency:

Lowfrequency（LF,30-500kHz）,Highfrequency（HF.10-15MHz）,Ultrahighfrequency（UHF,850-950MHz,2.4-2.5GHz,5.8GHz）Lowfrequencytagsarecheaperthananyofthehigherfrequencytags.Theyarefastenoughformostapplications,howeverforlargeramountsofdatathetimeataghastostayinareadersrangewillincrease.Anotheradvantageisthatlowfrequencytagsareleastaffectedbythepresenceoffluidsormetal.Thedisadvantageofsuchtagsistheirshortreadingrange.Themostcommonfrequen