《巴伦建筑理论》PPT课件

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1、Balun/UnunConstructionMike,N1IWOutline1:1&4:1BalundescriptionDesignConsiderationsConstructionMaterialsConstructionStepsPartsSourcesQuestions?BalunDescriptionBalunsforAntennasPurposeIsolatetransmissionlinefromantenna(suppresses“inverted-Lmode”)Providebalancedoutputcurrent

2、sintounequaldipolelegimpedancesMisconceptionsWillaffectantennabandwidthInefficient&pronetocoresaturationProvideslighteningprotectionWhyaBalun?TheBasicCurrentBalunThe4:1GaunellaCurrentBalunDesignConsiderationsHighchokingreactance,250Ωminimum(limitslowfrequencyresponse)Low

3、straycapacitance(limitshighfrequencyresponse)Shorttransmissionline,<<¼wave(Theshorter,thebetter)HighpowerhandlingMinimizeresistivelossesCorrectcoreselectionRobustmechanicaldesignDesignConsiderationsLineImpedance,Z0For1:1makeequaltoloadandlineimpedanceFor4:1,makegeometric

4、meanoflineandloadimpedance(e.g.,50Ωto200Ωrequires100Ωline)TransmissionlineexamplesParallelline(wrapwithScotchNo.27glasstape)50Ω:bifilarwound#14,wraponewirewith1layerofScotchNo.92tapetocontrolwirespacing100Ω:bifilarwound#14+Teflontubing50ΩCoaxRG303,RG142,RG400EnclosureLi

5、ghtweightMechanicalintegrityWeatherproofMaterialChoices…Choosemagneticssizeforpower≤0.5”ODcoresforQRPandreceiveapplications1.4”-1.5”ODcoresformatchedloadsupto1kW2.4”ODcoresforreliablelegallimit+CorescanalsobestackedChoosemagneticsmaterialforfrequencyµ=250for160M(Kmix)µ=1

6、25for80Mandup(Q1,61)µ=40for20Mandup(Q2,67)RodsandDonutsFerriteCoreExamples(Amidon)Part#O.DI.DlgtMaterialUFT-23-610.230inch0.120inch0.060inch61125FT-37-610.375inch0.187inch0.125inch61125FT-50-610.500inch0.281inch0.188inch61125FT-50A-610.500inch0.312inch0.250inch61125FT-50

7、B-610.500inch0.312inch0.500inch61125FT-82-610.825inch0.516inch0.250inch61125FT-87-610.870inch0.540inch0.250inch61125FT-114-611.141inch0.750inch0.295inch61125FT-114A-611.141inch0.750inch0.545inch61125FT-140-611.400inch0.900inch0.500inch61125FT-240-612.40inch1.400inch0.500

8、inch61125FerriteCoreExamples(Amidon)Part#O.DI.DlgtMaterialUPriceUS$FT-140-611.400inch0.900inch0.500inch