1、Designation: D4935 10Standard Test Method forMeasuring the Electromagnetic Shielding Effectiveness ofPlanar Materials1This standard is issued under the fixed designation D4935; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the ye
2、ar of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method provides a procedure for measuring theelectromagnetic (EM) shielding effectiveness (SE) of a pl
3、anarmaterial for a plane, far-field EM wave. From the measureddata, near-field SE values may be calculated for magnetic (H)sources for electrically thin specimens.2,3Electric (E) field SEvalues may also be calculated from this same far-field data, buttheir validity and applicability have not been es
4、tablished.1.2 The measurement method is valid over a frequencyrange of 30 MHz to 1.5 GHz. These limits are not exact, but arebased on decreasing displacement current as a result ofdecreased capacitive coupling at lower frequencies and onovermoding (excitation of modes other than the transverseelectr
5、omagnetic mode (TEM) at higher frequencies for thesize of specimen holder described in this test method. Anynumber of discrete frequencies may be selected within thisrange. For electrically thin, isotropic materials with frequencyindependent electrical properties of conductivity, permittivity,and pe
6、rmeability, measurements may be needed at only a fewfrequencies as the far-field SE values will be independent offrequency. If the material is not electrically thin or if any of theparameters vary with frequency, measurements should be madeat many frequencies within the band of interest.1.3 This tes
7、t method is not applicable to cables or connec-tors.1.4 UnitsThe values stated in SI units are to be regardedas standard. No other units of measurement are included in thisstandard.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresp
8、onsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:4D1711 Terminology Relating to Electrical Insulation3. Terminology3.1 DefinitionsFor definit
9、ions of terms used in this testmethod, refer to Terminology D1711.3.2 Definitions of Terms Specific to This Standard:3.2.1 dynamic range (DR), ndifference between the maxi-mum and minimum signals measurable by the system.3.2.1.1 DiscussionMeasurement of materials with goodSE require extra care to av
10、oid contamination of extremely lowpower or voltage values by unwanted signals from leakagepaths.3.2.2 electrically thin, adjthickness of the specimen ismuch smaller (filename for conversion toinput data for spreadsheet and graphing programs.X2.6 The computer program is shown in Fig. X2.1.FIG. X2.1 A
11、SCII Source Code for Fortran Compiler to GenerateProgram for Calculating Near-field SE Values From MeasuredFar-field SE ValuesD4935 1010ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this stan
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