Integrated-Adaptive-Beamforming-Antennas-for-Wirel

UNIVERSITYOFCALIFORNIA,LOSANGELESIntegratedAdaptiveBeamformingAntennasforWirelessCommunicationsYuanxunEthanWangDepartmentofElectricalEngineeringUniversityofCalifornia,LosAngelesUNIVERSITYOFCALIFORNIA,LOSANGELESOUTLINEObjective–”SmartAntennas”TechnicalApproachesIntegratedantennaarrayforDigitalBeamformingSmartAntennaReceiverwithSingle-RFChannelandDigitalBeamformingSmartAntennawithHybridDigital-AnalogBeamformingMillimeterWaveBroadbandAdaptiveBeamformingAntennaConclusionsUNIVERSITYOFCALIFORNIA,LOSANGELESHighdatarateMultipathStronginterferenceChallengesObjective-“SMARTANTENNAS”Objective:DevelophighperformanceadaptivebeamformingarraysystemwithadvancedsignalprocessingcapabilitySDMA(SpaceDivisionmultipleAddressing)TerminalmobilitySolution-AdaptiveBeamformingArrayContinuousbeamscanAdaptivebeamshapingUNIVERSITYOFCALIFORNIA,LOSANGELESLPFA/DDigitalSignalProcessing(Amplitude&Phase)~DesiredsignaldirectionLPFA/DLPFA/DLPFA/DInterferenceormultipathsignaldirectionDirectConversionMixerDigitalBeamformingUNIVERSITYOFCALIFORNIA,LOSANGELESTopViewFront-EndCircuitDirectConversionTypeSubstrate:50milRT/Duroid(εεεεr=10.2)ArraySpace:λλλλ/2(@5.8GHz)LNA:16dBGain(HP86576)Mixer:Double-balancedtype(SKY-60MH;Minicircuits)LNAsMixersIF(Baseband)OutputsLOInputQuasi-YagiAntennas13cm10cmIntegratedDBFArrayUNIVERSITYOFCALIFORNIA,LOSANGELES-40ºdirection+30ºdirection-60-40-200204060Angle[degree]-40-35-30-25-20-15-10-505RelativeGain[dB]ResultfromMeasuredElementPatternsResultfromIsotropicElementPatterns-60-40-200204060Angle[degree]-40-35-30-25-20-15-10-505RelativeGain[dB]ResultfromMeasuredElementPatternsResultfromIsotropicElementPatternsBeamSteeringUNIVERSITYOFCALIFORNIA,LOSANGELESNo.ofRFchannelsrequiredinconventionalsmartantennasystemsisN.(Nistheno.ofantennaelements)SystemcostandpowerconsumptionisNtimesofthatinasingleantennasystem.Antennawithmultiplefeedsisdifficulttodesign.Mutualcouplingbetweendifferentelementsisaseriousissue.AdaptiveArraywithSingleRFchannelObjective:ReducetherequiredNo.ofRFchannelstooneApproach:Spatialsamplingantennaarray&DigitalbeamformingUNIVERSITYOFCALIFORNIA,LOSANGELES500051005200530054005500560000.51500051005200530054005500560000.51500051005200530054005500560000.51500051005200530054005500560000.51SYSTEMBLOCKDIAGRAMAntennaelementsareturnedonandoffsequentiallySignalsfromdifferentelementsarecombinedtoformasinglefeedlineoutputSignalphaseandamplitudecanberestoredinDSPifthespatialsamplingspeedisfastenoughOnlyasingleRFchannelisrequiredUNIVERSITYOFCALIFORNIA,LOSANGELESSPATIALSAMPLERINTEGRATEDINAPLANARARRAYSpatialsampler(MUX)isrealizedusingPINdiodeswitchesIntegrationofswitchesintheantennaformsasimplelayoutforeasyimplementationOnlyoneelementisthroughateachinstance,whichcouldresultinlowermutualcouplingbetweendifferentantennaelementsBiasingPINDiodeOutputtoRFQuasi-yagiantenna5.8GHzspatialsamplingantennaarrayUNIVERSITYOFCALIFORNIA,LOSANGELESTIMEDOMAINSIGNAL–CHAMBERMEASUREMENTBasebandfrequency:250KHzSolidline:SpatiallysampledtimedomainwaveformforeachelementafterdemultiplexingDashedline:reconstructedtimedomainsignalwaveformafterlowpassfilterLinearprogressivephaseintheorderofantennaelementsisobserved.UNIVERSITYOFCALIFORNIA,LOSANGELESMEASUREDANTENNABEAMPATTERN+/-20degreescanisdemonstratedSidelobelevelislowerthan-13dBAsymmetricalpatternduetothemeasurementerrorcausedbythefinitebandwidthofsamplingscopeUNIVERSITYOFCALIFORNIA,LOSANGELESSwitchingofantennaelementseffectsfeednetwork.Howdoesthechangeinloadeffecttheradiatingantenna?Itispossibletoimproveintrinsicradiationpatternsbyswitchingtheantennaelementdynamically.FeedNetworktoArrayEffectsUNIVERSITYOFCALIFORNIA,LOSANGELESSwitchingbetweenamatchedandopencircuitedfeedchangestheloadthecurrentsontheantennamustdrive.Switchingofelementsaffectsmutualcoupling.Mutualcouplingbetweenelementsaffectsradiation,DOA,andbeamforming.FDTDutilizedtostudysurfacecurrentsofpatcharray.ArraySLLmaybereduced,beamsteeringaccuracyimproved.lSwitchPatchAntennaLocationOfSwitchUNIVERSITYOFCALIFORNIA,LOSANGELESThemostdesirableresultisfortheelementpatterninthearrayenvironmenttomatchtheelementpatternofanisolatedelement.Currentscomputedwithin-houseFDTDcodeSurfaceCurrentsonPatchAntennasUNIVERSITYOFCALIFORNIA,LOSANGELESDramaticreductioninsurfacecurrentsisachievedbycarefullyselectingthePINdiodeswitchlocation.Currentscomputedwithin-houseFDTDcodeSurfaceCurrentsonPatchAntennasUNIVERSITYOFCALIFORNIA,LOSANGELESWithpropertruncation,activeelementpatternmatchescloselytoisolatedelementpattern.Narrowingofthepatterniscausedbythereactiveterminationofthefeedlineshiftingthephaseofthesurfacecurrentsontheparasiticpatches.Impropertruncationandmatchedcasesshowdistortedpatternsduetomutualcoupling.H-planeco-polarizedpatternsActiveElementRadiationPatternsUNIVERSITYOFCALIFORNIA,LOSANGELESScanto0degrees.ArrayRadiationPatternsUNIVERSITYOFCALIFORNIA,LOSANGELESScanto-20degreesArrayRadiationPatternsUNIVERSITYOFCALIFORNIA,LOSANGELESSUMMARYAspatialsamplingantennaarraywithasingleRFchanneldevelopedandexperimented.Digitalsign