增大UBW微带天线的带宽

天线

HindawiPublishingCorporation

InternationalJournalofMicrowaveScienceandTechnologyVolume2009,ArticleID821515,7pagesdoi:10.1155/2009/821515

ResearchArticle

BandwidthEnhancementofUWBMicrostripAntennawithaModi edGroundPlane

N.Prombutr,1P.Kirawanich,1andP.Akkaraekthalin2

1Electrical2Electrical

EngineeringDepartment,MahidolUniversity,NakornPathom73170,Thailand

EngineeringDepartment,KingMongkut’sInstituteofTechnologyNorthBangkok,Bangkok10800,Thailand

CorrespondenceshouldbeaddressedtoN.Prombutr,egnpb@mahidol.ac.thReceived19January2009;Accepted22July2009RecommendedbyAfshinDaryoush

Thisarticlepresentsabandwidthenhancingtechniqueusingamodi edgroundplanewithdiagonaledges,rectangularslot,andT-shapecutforthedesignofcompactantennas.Theproposedlow-cost,compact-sizecircularpatchantennaon3cm×5.1cmprintedcircuitboard(FR-4)isdesignedandvalidatedthroughsimulationsandexperiments.ResultsshowthattheT-shapedgroundplanewiththepresenceofthediagonalcutsatthetopcornersandtherectangularslotscanincreasethebandwidth.Returnlossesof 19and 26dBforthe rstandsecondresonantfrequencies,respectively,canbeachievedwhenthedepthofthediagonalcutis5mm,thedimensionofeachrectangularslotis5×3mm,andtheT-shapedsizeis8×4mm,providinga28.67%widerbandwidththanFCCstandard.

Copyright©2009N.Prombutretal.ThisisanopenaccessarticledistributedundertheCreativeCommonsAttributionLicense,whichpermitsunrestricteduse,distribution,andreproductioninanymedium,providedtheoriginalworkisproperlycited.

1.Introduction

Ultra-wideband(UWB)technologyhasbeenregardedasoneofthemostpromisingwirelesstechnologiesthathaveacapabilityofrevolutionizinghighdataratetransmission.SincetheFCCreleaseofUWBwirelesscommunicationbandwidthof7.5GHz(3.1–10.6GHz),anumberofnewdevelopedtechniquestosupporthighdataratewirelesscommunicationforthenextgenerationtechnologieshavebeenrapidlyincreasing.Basically,themaximumachievabledatarateorcapacityfortheidealband-limitedadditivewhiteGaussiannoise(AWGN)channelisrelatedtothebandwidthandthesignal-to-noiseratiothroughShannon-Nyquistcriterion[1,2]:

C=Blog2(1+SNR),

(1)

whereCdenotesthemaximumtransmitdatarate,Bstandsforthechannelbandwidth,andSNRisthesignal-to-noiseratio.Fromthisprinciple,thetransmitdataratecanbeenhancedbyincreasingeitherthebandwidthoccupationorthetransmissionpower.However,thetransmissionpowercannotbereadilyincreasedsincemanyportabledevicesarebatterypoweredandthepotentialinterferenceshouldalsobe

avoided.Thus,alargefrequencybandwidthseemstobethepropersolutiontoachieveahighdatarate.

Inthisarticle,wereportatechniquetoenhancetheband-widthusingamicrostrip-fedplanarcirculardiscmonopole[3].Thecirculardiscmonopolewitha50-ΩmicrostripfeedlineisfabricatedontheFR4substrate.Toimprovethebandwidth,wemodi edtheoriginalgroundplanetobeT-shapedwithdiagonalcutsatthetopcornersandrectangularslotsonthebody.Applicationsofcornercuttechniquehavebeenpreviouslyemployedtoimprovetheimpedancebandwidthformicrostrippatchantennas[4–6].Thepreliminarysimulationresultsofourproposedantennaarecomparedwiththemeasuredones.Followingthisintroduction,therestofthepaperisorganizedasfollows.ThedetailoftheantennadesignandpreliminaryresultsfromsimulationsaredescribedinSection2,andSection3discussestheexperimentalresults.ThisworkconcludesinSection4.

2.AntennaDesign

ThegeometriesoftheantennasinourstudyareshowninFigure1.Weusethemicrostripstructurebecauseito ersmanyadvantages,suchasbeingcompact,inexpensive,and