通訊Cable連接器介紹

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ConnectorOverviewTrainingMay5,2003ConnectorAnatomyWhatisaConnector?AconnectorisadeviceusedtoconnecttocablesorotherdevicesthroughwhichelectromagneticenergyistransferredfromoneplacetoanotherBody-Contact-InsulatorBodyContactInsulatorConnectorAnatomyDiscontinuityCompensationStepsDielectricSupportBeadContactBarbSlottedContactCableAnatomyWhatisCable?CableisatransmissionlinethroughwhichelectromagneticenergyispropagatedandtransferredfromoneplacetoanotherJacket-Braid-Shield-Dielectric-CenterConductorConductorDielectricJacketShieldBraidAssistanceontheWeb

AmphenolRFNewsletterTechnicalQuestions:http:///rf_made_simple/techquestions.aspVSWRConversionCharts:http:///rf_made_simple/vswr.aspGlossary:http:///rf_made_simple/glossary.asp#1.TransmissionLineWhatisatransmissionline?AtransmissionlineisaconduitbywhichelectromagneticenergyistransferredfromoneplacetoanotherCoaxialCable-UnbalancedLine:Centerconductorsurroundedbyaconcentricdielectricandouterconductor-Mostpopulartypeoftransmissionline#1.TransmissionLineWhatisatransmissionline?AtransmissionlineisaconduitbywhichelectromagneticenergyistransferredfromoneplacetoanotherWaveguide:Rectangular,Circular#1.TransmissionLineWhatisatransmissionline?AtransmissionlineisaconduitbywhichelectromagneticenergyistransferredfromoneplacetoanotherPlanarTransmissionLine:Microstrip,Stripline,Coplanarwaveguidearemostcommon#1.TransmissionLineWhatisatransmissionline?AtransmissionlineisaconduitbywhichelectromagneticenergyistransferredfromoneplacetoanotherTwinLine-balancedline:twoparallelconductorsseparatedbyadielectric..#1.TransmissionLineThetypeoftransmissionlinewilldeterminetheconnectorstyleCableConnector-CoaxialCable,TwinLineSurfaceMountConnector-MicrostripTabLaunchConnector-Microstrip,Stripline,CoplanarEndLaunchConnector-Microstrip,CoplanarPinLaunchConnector-Microstrip,Stripline,Coplanar#2.ImpedanceOhm’sLaw#2.ImpedanceImpedance:TheimpedanceoftheconnectorgenerallymustmatchthatofthetransmissionlineNon-Constant 50,75ohm 50ohm 75ohmBNCTwinaxial BNC 7/16 1.6/5.6UHF SMB C,SC,HN TypeFTwinaxial MCX Mini-UHF TypeG 1.0/2.3 MMCX TNC SMA N OuterDiameter InnerDiameter DielectricConstant Impedance.063 .020 2.0 50Ohms.063 .012 2.0 75Ohms.276 .120 1.0 50Ohms

#3.FrequencyRangeFrequencyisthenumberofelectromagneticwavesthatpassagivenpointin1secondHertzistheunitoffrequencymeasurementGenerally,theRFperformanceofaconnectordegradesasthefrequencyisincreased(c=f)Wavelengthdecreases,thereforesmallerdisruptionscausemoreproblemsSpecifyingthefrequencywillmakeiteasierforthedesignengineertooptimizetheperformanceWheneverpossible,don’tspecifyahighfrequencyconnectorwhenalowfrequencyconnectorwillworkdothejob#3.FrequencyRangeGiga = 1,000,000,000 BillionMega = 1,000,000 Million Kilo = 1,000 ThousandMilli = 1/1000 OnethousandthMicro = 1/1,000,000 OnemillionthNano = 1/1,000,000,000 OnebillionthPico = 1/1,000,000,000,000 OnetrillionthFrequencyChart(GHz)#4.ReturnLossorVSWRAmeasureofhowmuchpowerisreflectedReturnLoss:Theportionofasignalthatislostduetoareflectionofpoweratalinediscontinuity.ReturnLossissimilartoVSWRandisgenerallypreferredintheCATVindustrytoaVSWRspecificationVSWR:AcronymforVoltageStandingWaveRatio.VSWRistheratioofvoltageappliedtovoltagereflected.Itisthemajorfactorcontributingtothetotalsignalefficiencyoftheconnector.Bestperformanceisachievedwhentheimpedanceofthecableandtheconnectorarethesame(matched)ComponentCablePowertransmittedintocomponentIncidentPowerReflectedPowerReturnLoss=Ratioofreflectedtoincidentpower

indBVSWR=Ratioofmaximumtominimumelectricfield(Voltage)#5.InsertionLossInsertionLossisexpressedindB,andisameasureofthetotallossofpowergoingthroughadeviceIL=-20*log(Pout/Pin)Includeslossesduetoreflection(usuallythedominantfactorunlesstheReturnLossisverylow<-26dB),pluslossesduetothediel