A Method for Generating a Standard Magnetic Field in ciircular waveguide 英文文献资料

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1、IEEETRANSACTIONSONINSTRUMENTATIONANDMEASUREMENT,VOL.37.NO,3,JUNE1989785AMethodforGeneratingaStandardMagneticFieldinaCircularWaveguideAbstract-Inordertominimizetheeffectofelectromagneticinter-ferenceandthesurroundingconductivematerialsinthecalibrationofsmallloopantennasusedabove

2、HFfrequencies,anewmethodforgen-eratingastandardmagneticfieldinacircularwaveguideisproposed.Anewtheorytoobtaintheaveragemagneticfieldstrengthincidentonareceivingloopisderivedbyplacingtheradiatingandreceivingcir-cularloopantennaswithinacircularwaveguideoperatedhelowthecutofffrequ

3、encyregion.Experimentswerecarriedoutandthetheoreticalandexperimentalvaluesagreewithin0.1dBbetween10and150MHz.I.INTRODUCTION--_L=0i--2Z=lz=z,NTHEHFfrequencyregion,thenear-zonemagneticIfieldradiatedbyasmallcircularloopantennaiswidelyFig.1.Geometryofloopantennasinacircularwaveguid

4、e.usedfortestingthesensitivityofbothreceiversandfieldintensitymetersequippedwithaloopantenna.Whenanplacedontheaxisofthecircularwaveguide.Itisassumedexternalinterferencefieldexists,thetestshouldbecar-thatuniformin-phaseelectriccurrentI:flowsinthera-riedoutinashieldedroom[l].Inth

5、eVHFrange,anddiatingloop,theradiusofthewiresoftheloopwindingexperimentusingsmallloopantennaswasrecentlycar-isnegligiblysmallcomparedwiththeloopradius,andtheriedout[2].IntheVHFrange,themagneticfieldiswallsofthecircularwaveguideareperfectconductivegreatlyaffectedbyconductiveobjec

6、tsaroundtheloopan-plates.SinceI:isonlyinthecpcomponent,theelectricaltennasincontrasttotheHFrange.Althoughtheanechoicfieldexistsonlyinthecpcomponent.Theelectricalfieldchamberisidealforthiskindoftest,itcoststoomuch.existsonlyinTEommodesbecausetheyaresymmetricalInordertolimittheef

7、fectoftheexternalinterferencefieldwithrespecttotheZaxis.andsurroundingobjectswhichdisturbthefield,atestsys-Inordertocarryouttheseriesexpansionintermsoftemwhichutilizesradiatingandreceivingloopantennasthemodesinthewaveguide,thespaceinthewaveguideplacedinacircularwaveguideandisus

8、edbelowthecut-isseparatedintothefirstregion[0