1、Designation: D 4935 10An American National StandardStandard Test Method forMeasuring the Electromagnetic Shielding Effectiveness ofPlanar Materials1This standard is issued under the fixed designation D 4935; the number immediately following the designation indicates the year oforiginal adoption or,
2、in the case of revision, the year 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) shiel
3、ding effectiveness (SE) of a planarmaterial 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
4、 applicability have not been established.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 o
5、ther than the transverseelectromagnetic 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 con
6、ductivity, permittivity,and permeability, 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
7、 band of interest.1.3 This test 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, associat
8、ed with its use. It is theresponsibility 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. Termino
9、logy3.1 DefinitionsFor definitions 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 g
10、oodSE require extra care to avoid 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
11、shown in Fig. X2.1.TABLE X1.1 Summary of Estimated IncertaintiesSource Systematic RandomMismatch 60.5 dB 60.5 dBPower instability in signal generator 60.4 dB 60.4 dBReceiver calibration 60.3 dB 60.1 dBTotal 61.2 dB 61.0 dBD4935109ASTM International takes no position respecting the validity of any pa
12、tent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revisio
13、n at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your com
14、ments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyright
15、ed by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-
16、mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).FIG. X2.1 ASCII Source Code for Fortran Compiler to GenerateProgram for Calculating Near-field SE Values From MeasuredFar-field SE ValuesD49351010
