网络分析仪原理

NetworkAnalyzerBasicsCopyright2000NetworkAnalyzerBasicsNetworkAnalyzerBasicsCopyright2000NetworkAnalysisisNOT.…RouterBridgeRepeaterHubYourIEEE802.3X.25ISDNswitched-packetdatastreamisrunningat147MBPSwithaBERof1.523X10...-9NetworkAnalyzerBasicsCopyright2000WhatTypesofDevicesareTested?DevicetypeActivePassiveIntegrationHighLowAntennasSwitchesMultiplexersMixersSamplersMultipliersDiodesDuplexersDiplexersFiltersCouplersBridgesSplitters,dividersCombinersIsolatorsCirculatorsAttenuatorsAdaptersOpens,shorts,loadsDelaylinesCablesTransmissionlinesWaveguideResonatorsDielectricsR,L,C'sRFICsMMICsT/RmodulesTransceiversReceiversTunersConvertersVCAsAmplifiersVCOsVTFsOscillatorsModulatorsVCAtten’sTransistorsNetworkAnalyzerBasicsCopyright2000DeviceTestMeasurementModelNFStimulustypeComplexSimpleComplexResponsetoolSimpleDCCWSweptSweptNoise2-toneMulti-ComplexPulsed-ProtocolfreqpowertonemodulationRFDet/ScopeParam.An.NFMtr.Imped.An.PowerMtr.SNAVNASAVSA84000TG/SADed.TestersI-VAbsol.PowerGain/FlatnessLCR/ZHarm.Dist.LOstabilityImageRej.Gain/Flat.Phase/GDIsolationRtnLs/VSWRImpedanceS-parametersCompr'nAM-PMRFICtestFullcallsequencePulsedS-parm.PulseprofilingBEREVMACPRegrowthConstell.EyeIntermodulationDistortionNFMeasurementplaneNetworkAnalyzerBasicsCopyright2000LightwaveAnalogytoRFEnergyRFIncidentReflectedTransmittedLightwaveDUTNetworkAnalyzerBasicsCopyright2000•Verifyspecificationsof“buildingblocks”formorecomplexRFsystems•Ensuredistortionlesstransmissionofcommunicationssignals–linear:constantamplitude,linearphase/constantgroupdelay–nonlinear:harmonics,intermodulation,compression,AM-to-PMconversion•Ensuregoodmatchwhenabsorbingpower(e.g.,anantenna)WhyDoWeNeedtoTestComponents?KPWRFM97NetworkAnalyzerBasicsCopyright2000TheNeedforBothMagnitudeandPhase4.Time-domaincharacterizationMagTime5.Vector-errorcorrectionErrorMeasuredActual2.Compleximpedanceneededtodesignmatchingcircuits3.Complexvaluesneededfordevicemodeling1.CompletecharacterizationoflinearnetworksHigh-frequencytransistormodelCollectorBaseEmitterS21S12S11S22NetworkAnalyzerBasicsCopyright2000AgendaWhatmeasurementsdowemake?Transmission-linebasicsReflectionandtransmissionparametersS-parameterdefinitionNetworkanalyzerhardwareSignalseparationdevicesDetectiontypesDynamicrangeT/RversusS-parametertestsetsErrormodelsandcalibrationTypesofmeasurementerrorOne-andtwo-portmodelsError-correctionchoicesBasicuncertaintycalculationsExamplemeasurementsAppendixNetworkAnalyzerBasicsCopyright2000TransmissionLineBasicsLowfrequencieswavelengthswirelengthcurrent(I)travelsdownwireseasilyforefficientpowertransmissionmeasuredvoltageandcurrentnotdependentonpositionalongwireHighfrequencieswavelengthorlengthoftransmissionmediumneedtransmissionlinesforefficientpowertransmissionmatchingtocharacteristicimpedance(Zo)isveryimportantforlowreflectionandmaximumpowertransfermeasuredenvelopevoltagedependentonpositionalonglineI+-NetworkAnalyzerBasicsCopyright2000TransmissionlineZo•Zodeterminesrelationshipbetweenvoltageandcurrentwaves•Zoisafunctionofphysicaldimensionsandr•Zoisusuallyarealimpedance(e.g.50or75ohms)characteristicimpedanceforcoaxialairlines(ohms)1020304050607080901001.00.80.70.60.50.91.51.41.31.21.1normalizedvalues50ohmstandardattenuationislowestat77ohmspowerhandlingcapacitypeaksat30ohmsNetworkAnalyzerBasicsCopyright2000PowerTransferEfficiencyRSRLForcompleximpedances,maximumpowertransferoccurswhenZL=ZS*(conjugatematch)MaximumpoweristransferredwhenRL=RSRL/RS00.20.40.60.811.2012345678910LoadPower(normalized)RsRL+jX-jXNetworkAnalyzerBasicsCopyright2000TransmissionLineTerminatedwithZoForreflection,atransmissionlineterminatedinZobehaveslikeaninfinitelylongtransmissionlineZs=ZoZoVrefl=0!(alltheincidentpowerisabsorbedintheload)VincZo=characteristicimpedanceoftransmissionlineNetworkAnalyzerBasicsCopyright2000TransmissionLineTerminatedwithShort,OpenZs=ZoVreflVincForreflection,atransmissionlineterminatedinashortoropenreflectsallpowerbacktosourceIn-phase(0o)foropen,out-of-phase(180o)forshortNetworkAnalyzerBasicsCopyright2000TransmissionLineTerminatedwith25WVreflStandingwavepatterndoesnotgotozeroaswithshortoropenZs=ZoZL=25WVincNetworkAnalyzerBasicsCopyright2000High-FrequencyDeviceCharacterizationTransmittedIncidentTRANSMISSIONGain/LossS-ParametersS21,S12GroupDelayTransmissionCoefficientInsertionPhaseReflectedIncidentREFLECTIONSWRS-ParametersS11,S22ReflectionCoefficientImpedance,AdmittanceR+jX,G+jBReturnLossG,rT,tIncidentReflectedTransmittedRBAAR=BR=NetworkAnalyzerBasicsCopyright2000ReflectionParametersdBNoreflection(ZL=Zo)rRLVSWR01Fullreflection(ZL=open,short)0dB1=ZL-ZOZL+OZReflectionCoefficient=VreflectedVincident=rFG=rGReturnloss=-20log(r),VoltageStandingWaveRatioVSWR=EmaxEmin=1+r1-rEmaxEminNetworkAnalyzerBasicsCopyright2000SmithChartReviewSmithChartmapsrectilinearimpedanceplaneontopolarplane0+R+jX-jXRectilinearimpedanceplane.-90o0o180o+-.2.4.6.81.090o0PolarplaneZ=ZoL=0GConstantXConstantRSmithchartGLZ=0=±180O1(short)Z=L=0O1G(open)NetworkAnalyzerBasicsCopyright2000TransmissionParametersVTransmi