(北斗)A-Compact-Frequency-Reconfigurable-Patch-Anten

IEEEANTENNASANDWIRELESSPROPAGATIONLETTERS,VOL.13,2014967ACompactFrequency-ReconfigurablePatchAntennaforBeidou(COMPASS)NavigationSystemChaoSun,HuiliZheng,LingfeiZhang,andYingLiu,Member,IEEEAbstract—Acompactfrequency-reconfigurableshortingloadedpatchantennawiththecapabilitytoswitchbetweenthreeoper-atingbandsofBeidou(COMPASS)navigationsystem(BDNS)(E2,E6,andE5b)isproposedinthisletter.Thereconfigurableabilityoftheproposedantennaisachievedviaacircularrotationalmanualmotion.Thefeatureoftheshortingloadisutilizedintheproposedantenna.Byrotatingthetoplayeroftheantenna,theshortingprobeinthetoplayercanbeshortedtothegroundbydifferentsetsofshortingpinswithdifferentlengthinthebottomlayeroftheantenna,whichmeansthatthefrequencyagilityisachieved.Simu-latedandmeasuredresultsshowthattheproposedantenna,whichhasanoverallvolumeofmmmm,hasgoodperformanceinallthethreeoperatingbands.Thus,thedesignmethodproposedinthisletterprovidesasolutionformultibandpatchantennathatishardtodesignusingtraditionalapproaches.IndexTerms—Circularpolarization,frequency-reconfigurableantenna,rotatablereconfigurationantenna,shortingloadedpatchantenna,tribandantenna.I.INTRODUCTIONWITHthedevelopmentofChineseBeidouorCOMPASSNavigationSystem(BDNS),antennasusedforBDNShavereceivedmuchattention.AccordingtoInternationalTelecommunicationUnion(ITU)filings[1],BDNSbroadcastsinthreefrequencybandsknownasE2(1559–1591MHz),E6(1260–1279MHz),andE5b(1192–1215MHz).Acompactcircularlypolarized(CP)antennathatcancoverallthreeofthesebandsisneededfortheapplicationsofBDNS.GNSSantenna[2]withbandwidththatcoversallthespectraofthefouroperatingsystems(1164–1610MHz)canbeanalter-nativechoice.However,thewidebandfeaturemakesthemtoolargeinsize.Somedual-bandantennashavebeenproposedforthetribandapplicationsofGPS[3]duetothetwolowerbands[L5(1164–1192MHz)andL2(1215–1237MHz)]beingquiteclosetoeachotherandcanberegardedasonewideband.ThismethodisnotfeasibleforBDNSsincethetwolowerbandsofBDNSaretoofaraparttoberegardedasoneband.Someef-fortshavealreadybeencarriedouttowardthedesignoftribandantennas.However,mostofthesereportedtribandantennas,in-cludingstackedpatchantenna[4],monopole[5],andslotan-tenna[6],aredesignedforWLAN/WIMAXapplications,andManuscriptreceivedMarch20,2014;revisedApril29,2014;acceptedMay06,2014.DateofpublicationMay21,2014;dateofcurrentversionMay26,2014.TheauthorsarewiththeScienceandTechnologyonAntennaandMicrowaveLaboratory,XidianUniversity,Xi’an710071,China(e-mail:[e-mail];[e-mail];[e-mail];[e-mail]).ColorversionsofoneormoreofthefiguresinthisletterareavailableonlineatficulttodesignatribandBDNSwiththetraditionaldesignmethod,andthereisnoreportedtribandBDNSantennauntilnow.TofillintheblankofBDNStribandantennaandovercomethepresentproblem,thefrequencyreconfigurationtechniqueisadoptedasthesolution.Basedonthewaytoachieveperfor-manceagility,thereconfigurableantennascanbeclassifiedintotwocategories:theonethatuseselectricalswitch[7],[8]andtheonethatusesmechanicalswitch[9].Theformerone,whichemploysp-i-ndiodes[7]orlumpedelements[8]astheswitchcircuit,isthemostcommonlyusedswitchingmethod.How-ever,extrabiascircuitisneeded,whichincreasesthevolumeandthedesigncomplexityoftheantenna.Thelatterone,me-chanicalswitchreconfigurableantenna,asanewkindofrecon-figurableantenna,isproposedbyTawketal.[9].Inthatpaper,onefeedportisassignedtoswitchbetweenfourmonopoleswithdifferentstructurebyrotatingtheantenna.However,foursepa-ratedmonopolesmaketheantennaverylargeandthestructurereuseisactuallynotrealized.Besidesthat,unlikethepatchan-tennathatiswidelyusedinthesatellitenavigationsystem[2],theradiationpatternofmonopoleisnotidealfortheBDNS.Inthisletter,acompactreconfigurablepatchantennathatiscapableofswitchingbetweenthreebandsisproposed.Theshortingstructureisadoptedtorealizethefrequencyagility.Asitiswellknown,shortingloadedtechniqueisacommonminia-turizationmethod,andthelengthoftheshortingstructurehasanobviousimpactontheresonantfrequencyofthepatchantenna.Byrotatingthetoplayeroftheproposedantennamanually,thepatchcanbeshortedtothegroundbydifferentsetsofshortingpinsinthebottomlayeroftheantenna,whichmeansthatitiscapableofswitchingbetweenseveraldifferentoperatingbands.Allthestatesoftheantennashareasamepatchandthevolumeoftheantennaisrationallyutilized.Simulationandmeasure-mentshowgoodresults,andtheyareingoodagreement,whichmeansthattheproposedantennacanbeaneffectivesolutionformultibandpatchantennas.II.DESIGNOFTHEPROPOSEDANTENNAA.FeedNetworkConfigurationIntheproposedpatchantenna,thedual-feedconfigurationisadoptedtogenerateCPradiation,andacompactbroad-band90phaseshifterfeednetworkhasbeendesigned.TheschematicandphotographofthedesignedfeednetworkareshowninFig.1.ThefeednetworkconsistsofoneWilkinsonpowerdividerandonebroadbandphaseshifterintheformofastriplinewithtwoparalle