简介:Theeffectofthespatialcharacteristicsofantennaarrayonsmartantennasystemscannotbeneglected.Inthepaper,therelationbetweenspatialcorrelationandinter-antennadistance,impingingangle,anglespreadisfirstinvestigated.Withthesamebeamformingalgorithm,wesimulatetheperformanceofsmartantennasystemwithdifferentAngleSpread(AS)valuesontheconditionsofidealandrealAngleofArrival(AOA)estimation.TheresultsshowthatwiththeidealAOAestimation,theAOAisenoughaccuratetoguaranteethatthesystemonlyhaslittleperformancedegradationeveninthecaseof20degreeeASvaluewhiletherealAOAestimationinfluencedbychannelenvironmentdegradestheperformanceveryobviously,uptoabout7dB.
简介:TheElectromagneticCompatibilityandDistributionofAntennaSystem¥B.FWang;S.Z.adns&Y.L.Yao(Dept.ofElect.Eng.,BeijingUniversityofA...
简介:一个表面波浪激动的血浆列能充当一条血浆天线。实验被执行学习电流和传导性如此的一条血浆天线的分布,领域,功率模式,择向性和效率。另外,一条相等的金属性的铜天线被建立,它的天线参数与血浆天线的相比。我们的调查结果显示在血浆天线的泛音的力量内容是与铜天线相比同样突出的更多(它仅仅产生基本频率)。然而,为两条天线的力量模式是相当类似的。在血浆天线的领域里关于泛音的产生提供更质的理解,双性人光谱的分析被执行在当前的变化学习非线性的相互作用。血浆天线的一些特定的特征在我们的学习被调查,它可以关于常规金属性的天线提高血浆天线的申请前景。
简介:Anovelellipsoidalhelicalantennaisproposedandstudiedinthisletter.Asaspecialin-stance,thehemisphericalhelicalantennasareanalyzedfirstly,whichindicatesthatthecharacteristicsofatwo-armunitarebetterthanthatofasingle-armunit.Basedonthis,theellipsoidalhelicalantenna,formedbychangingtheaxialdirection’sdimensionofthetwo-armhemisphericalhelicalantenna,isanalyzedbythemomentmethodwithcurvedbasicandtestingfunction.TheeffectstoVSWR(VoltageStandingWaveRatio),gain,polarizationandpatternsbytheaxialdirection’sdimensionsareinves-tigated.Thestudyresultsprovidedependablegisttothechoiceofantennaformataccordingtothepracticalrequirements.
简介:Averticalantennaembeddedinearthwithconductivecoatinghasbeeninvesti-gatedbyemployingthemethodofintegralequation.ThistopicisavailabletoEM-MWD(Elec-tromagneticMeasurement-While-Drilling)system,whichisanewrealtimesystemfordrillingmeasurement.Undertheconditionthatthewavenumberoftheearthismuchlargerthanthatoftheair,acurrentintegralequationhasbeenderived.Afterthecurrentdistributionhavingbeendetermined,theelectricfieldstrengthontheearthsurfacehasbeenpredictedanditsdependencesontheoperatingfrequencyandthedepthofthewellhavebeendiscussedaswell.
简介:Amethodhasbeendevisedtoanalyzemultilayerelectricallythickcircularmi-crostripantennaexcitedbyaprobe.Thecurrentontheprobeistakentobeuniform.Thismethodwasverifiedbyanalysisandexperimentofanelectricallythickcircularmicrostripan-tennawithanairgap.BasedonthefreespaceelectricdyadicGreen’sfunction,thefieldexpressionofanhorizontalelectricdipole(HED),whichislocatedatanypointofthemultilayermediaandpointsinanydirection,hasbeenderived.ByusingthisfieldexpressionandtheRichmondre-actionequation,anintegralequationintermsofelectriccurrentonthepatchisformulated.Byproperlychoosingcurrentexpansionmodes,thismethodcanbeusedforanelectricallythickmi-crostripantenna.Thetheoreticalresultsagreeverywellwithexperimentaldataforanelectricallythickcircularmicrostripantennawithanairgap.
简介:Anechoicchambersareusedforindoorantennameasurements.Thecommonmethodofconstructingananechoicchamberistocoverallinsidewallsbytheelectromagneticabsorbers.Inthispaper,afullymetallicsphericalchamberstructureispresentedinwhichthepropagationoftheelectromagneticwavesinsidethechamberiscontrolledandtheyareguidedtoanabsorber.Intheproposedmethod,anappropriatequietzoneisobtained,andunlikeordinaryanechoicchambers,theabsorberusageamountisreducedgreatly.Theperformanceofthechamberisevaluatedbysimulation.Theresultsshowthattheproposedmethodcouldprovideausefultechniquefortheindoorantennameasurements.
简介:Anewultra-wide-band(UWB)hornantennabasedonthenonradiativedielectricwaveguide(NRD-guide)wasproposedtosolvetheproblemofUWBantennas,TEMhornsforexample,generallysufferfromlargesideleakage.Theruleofthetheoreticalselectionofitsparameters,ifNRD-guideisusedastheUWBantennas,isstudiedfirstly,thentheradiationcharacteristicsforanopen-endedNRD-guidearecalculatedbyFDTD(finite-differencetime-domain)method.
简介:Inthisarticleabridgebetweentheexpectedcomplexityandperformanceofspheredecoding(SD)isbuilt.TheexpectedcomplexityofSDforinfinitelatticesistheninvestigated,whichnaturallyistheupper-boundofthoseforallthefinitelatticesifgivenbythesamechannelmatrixandsignalnoiseratio(SNR).SuchexpectedcomplexityisanimportantcharacterizationofSDinmulti-antennasystems,becausenomatterwhatmodulationschemeisusedinpractice(generallyithasfiniteconstellationsize)thisupper-boundholds.AbovebridgealsoleadstoanewmethodofdeterminingtheradiusforSD.Thenumericalresultsshowboththerealvalueandupper-boundofaveragesearchednumberofcandidatesinSDfor16-QAMmodulatedsystemusingtheproposedsphereradiusdeterminingmethod.MostimportantofallnewunderstandingsofexpectedcomplexityofSDaregivenbasedonabovementionedtheoreticanalysisandnumericalresults.
简介:OptimizationofantennaarraypatternusedinaspaceborneSyntheticApertureRadar(SAR)systemisconsideredinthisstudy.Arobustevolutionaryalgorithm,Non-dominatedSortingGeneticAlgorithms(theimprovedNSGA-Ⅱ),isappliedonaspaceborneSARantennapatterndesign.Thesystemconsistsoftwoobjectivefunctionswithtwoconstraints.Paretofrontsaregeneratedasaresultofmulti-objectiveoptimization.AfterbeingvalidatedbyatestproblemZDT4,thealgorithmsareusedtosynthesizespaceborneSARantennaradiationpattern.ThegoodresultswithlowAmbi-guity-to-SignalRatio(ASR)andhighdirectivityareobtainedinthepaper.
简介:Anovelmethodfordesigningabeam-switchingantennawiththeplanedipoleispresented.Theantennaiscomposedofdoubledipolesplacedatthecenterofanactivesquarestructurethatisdividedinfourequalsectorsbymetallicsheets.Metallicpatchesattheoutsideofthestructureareusedtoenhancetheradiationperformanceoftheantenna.Ineachstep,thediodesinonesectorareon,whereasotherdiodesareoff.Thesectorwithoff-statediodesdefinesthedirectionoftheradiationpattern.AnantennamodelisdesignedonthesubstrateofFR4.Theproposedantennaoperatesfrom4.8GHzto5.5GHzwithgainof6.3dBiandF/B(fronttobackratio)of13.2dBiwhentheoperatingfrequencyis5.2GHz.Theantennaradiationpatterncanbesweptintheentireazimuthplaneinfourstepswitha3dBbeamwidthof90.Theresultsrevealthattheantennacouldbeusedinthebasestationofthewirelesscommunicationsystems.
简介:Consideringtheshortcomingsoftheexistingvehicle-to-vehicle(V2V)communicationantennas,thispaperproposesaregularhexagonbroadbandmicrostripantenna.ByloadingshortingpinsandetchingV-shapeslotswithdifferentsizeateachangleoftheregularhexagonpatch,itrealizesimpedancematchingandobtainsbetterimpedancebandwidth.Thesimulatedresultsshowthattherelativebandwidthofthisantennareaches35.55%,coversthefrequencybandof4.74GHzto6.79GHz.Theantennaacquiresanomni-directionalradiationpatterninthehorizontalplanewhoseoutofroundnessislessthan0.5dB.Inaddition,theantennaismanufacturedandtested,whosetestedresultsarebasicallyconsistentwithsimulatedresults.Becausetheheightofantennais3mm,itiseasytobehiddenonroofofavehicleforV2Vcommunication.