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1Progressinultra-widebandnotchantennaAbstract:Withthedevelopmentofwirelesscommunicationtechnology,withashort-rangehigh-speedwirelesscommunicationsadvantagesofultra-wideband(UWB)technologyhasbecomeahotresearchinthefieldofModern’sultra-widebandwirelesscommunications.Ultrawidebandantennahaslosofadvantages,suchasasimplestructure,lowpowerconsumptionandeasytointegrate[1],becausetheultra-widebandsystemwouldoverlapothersystemsandbemutuallyinterferentedbyeachoher,ithasagreatsignificancetodesignanotchcharacteristicofultra-widebandantenna.Thedevelopmentofultrawidebandantennaisfacingmanychallengecurrently[2].However,wehavereasontobelievethatinthenextfewyearstherewillbeabiggerbreakthrough.Thedevelopmentinthecivilianultrabroadbandandmobilecommunicationdevicesofultra-widebandantennaswilltowardadirectionofminiaturization,highefficiency,stablegain,widebandandultrashortandfastpulseresponse[3].Keywords:Band-Notched,Ultra-Wideband,Antenna,interferences,wirelesscommunication1.TheultrawidebandantennaUltra-widebandantenna,bydefinition,isakindofantennawhichhaswidebandwidthparticularly,datingbackmorethan50yearsofdevelopmenthistory.Itisacommunicationstechnologybyusingaparticularlywidespectrumofultrashortpulsespulsetocommunicating.Itisalsoknownasbasebandcommunications.Whoseoperatingfrequencytomeetoneofthefollowingconditionscanbecalledultra-widebandantennasystem[4].I.Bf=2fH−fLfH+fLWherein，fH，fLarethehighestandlowestfrequenciesin-10dB2bandwidthsystem，whenBf＞0.20,calledthesystemultra-widebandsystems.II.WhentheabsolutebandwidthfH−fL≥500MHz，wherefH和fLarethehighestandlowestfrequencies-10dBbandwidthsystem,thissystemcanalsobereferredtoasultra-widebandsystems.Becausethelargeamountofinformation,thesimplestructure,lowcost,easytoimplement,lowpower,goodreliabilityandhighsecurityfeatures,ultra-widebandsystemshasbeenwidelyusedinthefieldofwirelesscommunications.Ultra-widebandsystemshasbeenwidelyusedinthefieldofwirelesscommunication.Itismainlyusedinthefieldofradartechnologyduringtheearlytime.1972UWBpulsedetectorapplicationforaUSpatent;In1978appearedintheoriginalUWBcommunicationsystem;1984,UWBsystemsuccessfullycarriedout10kmtest;In1990theUSDefenseAdvancedProjectsAgency(DARPA)beganUWBtechnologyforverification.InFebruary2002,FCCapprovedUWBtechnologyforcivilianmainreasonsfortheslowdevelopmentofUWBtechnology:in1994itwasmainlyconfinedtomilitaryuse,limitingthethird-partydevelopmentsupportUWBhardwareandsoftware;SinceUWBusesmanyspecialband,FCCapprovedUWBtechnologyforslowprogress;UWBinterferencecausedbyUWBalsohinderedthepaceofdevelopment;[5]2.ThenotchtechnologySincetheelectromagneticsignalwouldinterferewithothercommunicationdevicesduringthecommunicationprocess.Sointheindoorshort-rangeultra-widebandantennawouldpreventinterferencewithotherdevicesorinterferencebyotherequipment[6].Inordertoreducemutualinterferencebetweensystemsandimprovespectralefficiency,wecantakemanydifferentwaysinwhichthesimplestandmostdirectwayismakingtheultrawidebandantennahavingalargereflectioncoefficientinthecorrespondingfrequencyband,notchresistanceandexhibitsslowtoacceptthestatusofthetransmissionappears[7].33.NotchoftheultrawidebandantennaTheconceptofnotchoftheultrawidebandantennawasfirstproposedbyAmericanengineersSchana•H•G.Afterthat,therehasbeenalotofresearchaboutultra-widebandantennanotchcharacteristicofthesestudiescanprobablywerefivecategories[8]:①theintroductionoftheantennaradiatingelementscharacteristicnarrowresonancestructure;②theintroductionofthenarrow-bandresonancecharacteristicsoftheresonantstructurenode;③theintroductionofnarrow-bandresonancecharacteristicstructureinthefeedbackbranch;④theuseofseparatestructure;⑤usingelectronictuningoscillationtechnology.4.Progressonultra-widebandnotchantennaToday,withtherapiddevelopmentofultra-wideband,UWBisbecomingmorepowerfulandmorewidely.Suchas:UWBantennawithC-shapedslot[9],Asmallnovelultrawidebandantennawithdualband-notchedcharacteristicsisproposedandinvestigatedindetailtoworkmorestably;AcompactprintedUWBantennawithtripleband-notchedcharacteristics[10],acompactprintedultra-widebandantennawithtripleband-notchedcharacteristicsispresentedwhichcanmakeantennaworkmorestablyinsomefrequencyrange;AnovelminiaturizedUWBantennawithfourband-notchedcharacteristics[11]Inordertoeliminateunwantedinterferences,UWBantennaswithsingleordualbandrejectionfunctionhavebeenreported;AcompactdiscUltrawideBand(UWB)antennawithquintuplebandrejections[12]TorealizeacompactUWBantennawithmultipleband-notchedfunctions,therearemainlytwolimitations.Onelimitationisduetothemutualcouplingofmultiband-rejectionelements,whichwouldresultintheincreaseofdesigncomplexity.TheotherlimitationisduetospacerestrictioninthesubstrateofthecompactUWBantenna[13].4Althoughthedevelopmentofultra-widebandantennaisfacingmanychallenges,wehavereasontobelievethatinthenextfewyearstherewillbeabiggerbreakthrough,Developmentinthecivilianultrabroadbandandmobilecommunicationdevicesofultrashort-bandantennaswilltowardadirectionofminiaturization,highefficiency,stablegain,widebandandfastpulseresponseultrashort.Refer