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S-parametersAnintroductionAuthor:JeanBurnikellPresented:MartynGaudion“blackbox”3S-parameters“blackbox”Theexternalbehaviourofthisblackboxcanbepredictedwithoutanyregardforthecontentsoftheblackbox.4S-parameters“blackbox”5S-parameters“blackbox”ornetworkmayhaveanynumberofports.Thisdiagramshowsasimplenetworkwithjust2ports.6S-parameters“blackbox”ornetworkmayhaveanynumberofports.Thisdiagramshowsasimplenetworkwithjust2ports.Note:Aportisaterminalpairoflines.7S-parameters“blackbox”anddetectingwhatwavesexitfromeachport.Power,voltageandcurrentcanbeconsideredtobeintheformofwavestravellinginbothdirections.8S-parameters“blackbox”anddetectingwhatwavesexitfromeachport.9S-parameters!S-parameterconventionalwaysreferstotherespondingportfirst!IhaveseenS-parametersdescribedasS11,S21,etc.Canyouexplain?14S-parameters=b1/a1S12=b1/a2S21=b2/a1S22=b2/a2Noteagainhowthesubscriptfollowstheparametersintheratio(S11=b1/a1,etc...)IhaveseenS-parametersdescribedasS11,S21,etc.Canyouexplain?16S-parameters(i.e.theyhavemagnitudeandangle)becauseboththemagnitudeandphaseoftheinputsignalarechangedbythenetwork.(Thisiswhytheyaresometimesreferredtoascomplexscatteringparameters).18S-parameters(orthemodulusandthephaseangle)ofeachofthefourcomplexscatteringparameters.19S-parameters(orloss)yougetisusuallymoreimportantthanhowmuchthesignalhasbeenphaseshifted.20S-parameters