Designation:D4935−18StandardTestMethodforMeasuringtheElectromagneticShieldingEffectivenessofPlanarMaterials1ThisstandardisissuedunderthefixeddesignationD4935;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thistestmethodprovidesaprocedureformeasuringtheelectromagnetic(EM)shieldingeffectiveness(SE)ofaplanarmaterialforaplane,far-fieldEMwave.Fromthemeasureddata,near-fieldSEvaluescanbecalculatedformagnetic(H)sourcesforelectricallythinspecimens.2,3Electric(E)fieldSEvaluesarealsoabletobecalculatedfromthissamefar-fielddata,buttheirvalidityandapplicabilityhavenotbeenestab-lished.1.2Themeasurementmethodisvalidoverafrequencyrangeof30MHzto1.5GHz.Theselimitsarenotexact,butarebasedondecreasingdisplacementcurrentasaresultofdecreasedcapacitivecouplingatlowerfrequenciesandonovermoding(excitationofmodesotherthanthetransverseelectromagneticmode(TEM))athigherfrequenciesforthesizeofspecimenholderdescribedinthistestmethod.Selectanynumberofdiscretefrequencieswithinthisrange.Forelectricallythin,isotropicmaterialswithfrequencyindepen-dentelectricalpropertiesofconductivity,permittivity,andpermeability,measurementswillpossiblybeneededatonlyafewfrequenciesasthefar-fieldSEvalueswillbeindependentoffrequency.Ifthematerialisnotelectricallythinorifanyoftheparametersvarywithfrequency,makemeasurementsatseveralfrequencieswithinthebandofinterest.1.3Thistestmethodisnotapplicabletocablesorconnec-tors.1.4Units—ThevaluesstatedinSIunitsaretoberegardedasstandard.Nootherunitsofmeasurementareincludedinthisstandard.1.5Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafety,health,andenvironmentalpracticesanddeter-minetheapplicabilityofregulatorylimitationspriortouse.1.6Thisinternationalsta...
