ASTM D4935-18
(Test Method)Standard Test Method for Measuring the Electromagnetic Shielding Effectiveness of Planar Materials
Standard Test Method for Measuring the Electromagnetic Shielding Effectiveness of Planar Materials
SIGNIFICANCE AND USE
4.1 This test method applies to the measurement of SE of planar materials under normal incidence, far-field, plane-wave conditions (E and H tangential to the surface of the material).
4.2 The uncertainty of the measured SE values is a function of material, mismatches throughout the transmission line path, dynamic range of the measurement system, and the accuracy of the ancillary equipment. An uncertainty analysis is given in Appendix X1 to illustrate the probability of uncertainty achieved by an experienced operator using good equipment. Deviations from the procedure in this test method will increase this uncertainty.
4.3 Approximate near-field values of SE can be calculated for both E or H sources by using measured values of far-field SE. A program can be generated from the source code in Appendix X2 that is suitable for use on a personal computer.
4.4 This test method measures the net SE caused by reflection and absorption. The reflected and absorbed power measurement is accomplished by the addition of a calibrated bidirectional coupler to the input of the holder.
SCOPE
1.1 This test method provides a procedure for measuring the electromagnetic (EM) shielding effectiveness (SE) of a planar material for a plane, far-field EM wave. From the measured data, near-field SE values can be calculated for magnetic (H) sources for electrically thin specimens.2,3 Electric (E) field SE values are also able to be calculated from this same far-field data, but their validity and applicability have not been established.
1.2 The measurement method is valid over a frequency range of 30 MHz to 1.5 GHz. These limits are not exact, but are based on decreasing displacement current as a result of decreased capacitive coupling at lower frequencies and on overmoding (excitation of modes other than the transverse electromagnetic mode (TEM)) at higher frequencies for the size of specimen holder described in this test method. Select any number of discrete frequencies within this range. For electrically thin, isotropic materials with frequency independent electrical properties of conductivity, permittivity, and permeability, measurements will possibly be needed at only a few frequencies as the far-field SE values will be independent of frequency. If the material is not electrically thin or if any of the parameters vary with frequency, make measurements at several frequencies within the band of interest.
1.3 This test method is not applicable to cables or connectors.
1.4 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D4935 − 18
Standard Test Method for
Measuring the Electromagnetic Shielding Effectiveness of
1
Planar Materials
This standard is issued under the fixed designation D4935; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
1.1 Thistestmethodprovidesaprocedureformeasuringthe
mine the applicability of regulatory limitations prior to use.
electromagnetic (EM) shielding effectiveness (SE) of a planar
1.6 This international standard was developed in accor-
material for a plane, far-field EM wave. From the measured
dance with internationally recognized principles on standard-
data, near-field SE values can be calculated for magnetic (H)
2,3 ization established in the Decision on Principles for the
sources for electrically thin specimens. Electric (E) field SE
Development of International Standards, Guides and Recom-
values are also able to be calculated from this same far-field
mendations issued by the World Trade Organization Technical
data, but their validity and applicability have not been estab-
Barriers to Trade (TBT) Committee.
lished.
1.2 The measurement method is valid over a frequency 2. Referenced Documents
4
rangeof30MHzto1.5GHz.Theselimitsarenotexact,butare
2.1 ASTM Standards:
based on decreasing displacement current as a result of
D1711Terminology Relating to Electrical Insulation
decreased capacitive coupling at lower frequencies and on
overmoding (excitation of modes other than the transverse
3. Terminology
electromagnetic mode (TEM)) at higher frequencies for the
3.1 Definitions—For definitions of terms used in this test
size of specimen holder described in this test method. Select
method, refer to Terminology D1711.
any number of discrete frequencies within this range. For
3.2 Definitions of Terms Specific to This Standard:
electrically thin, isotropic materials with frequency indepen-
3.2.1 dynamic range (DR), n—differencebetweenthemaxi-
dent electrical properties of conductivity, permittivity, and
mum and minimum signals measurable by the system.
permeability, measurements will possibly be needed at only a
3.2.1.1 Discussion—Measurement of materials with good
few frequencies as the far-field SE values will be independent
SE require extra care to avoid contamination of extremely low
of frequency. If the material is not electrically thin or if any of
power or voltage values by unwanted signals from leakage
the parameters vary with frequency, make measurements at
paths.
several frequencies within the band of interest.
3.2.2 electrically thin, adj—thickness of the specimen is
1.3 This test method is not applicable to cables or connec-
1
much smaller (< ⁄100) than the electrical wavelength within the
tors.
specimen.
1.4 Units—The values stated in SI units are to be regarded
3.2.3 far field, n—that region where vectors E and H are
asstandard.Nootherunitsofmeasurementareincludedinthis
orthogonaltoeachotherandbotharenormaltothedirectionof
standard.
propagation of energy.
1.5 This standard does not purport to address all of the
3.2.4 near field, n—that region where E and H are not
safety concerns, if any, associated with its use. It is the
related by simple rules.
3.2.4.1 Discussion—The transition region between near
1
This test method is under the jurisdiction of ASTM Committee D09 on
field and far field is not abrupt but is located at the distance
Electrical and Electronic Insulating Materials and is the direct responsibility of
close to λ/2π from a dipole source, where λ is the free-space
Subcommittee D09.12 on Electrical Tests.
wave length of the frequency of the source. It is possible this
Current edition approved May 1, 2018. Published May 2018. Originally
approved in 1989. Last previous edition approved in 2010 as D4935–10. DOI: concept of regions is further blurred by reradiating as a result
10.1520/D4935-18.
2
Wilson, P. F., and Ma, M. T., “A Study of Techniques for Measuring the
4
Electromagnetic Shielding Effectiveness of Materials,” NBS Technical Note 1095, For referenced ASTM standards, visit the ASTM website, www.astm.org, or
May 1986. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
3
Adams, J. W., and Vanzura, E. J., “Shielding Effectiveness Measurements of Standards volume information, refer to the standard’s Document Summary page on
Plastics,” NBSIR 85-3035, January 1986.
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D4935 − 10 D4935 − 18
Standard Test Method for
Measuring the Electromagnetic Shielding Effectiveness of
1
Planar Materials
This standard is issued under the fixed designation D4935; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method provides a procedure for measuring the electromagnetic (EM) shielding effectiveness (SE) of a planar
material for a plane, far-field EM wave. From the measured data, near-field SE values maycan be calculated for magnetic (H)
2,3
sources for electrically thin specimens. Electric (E) field SE values mayare also able to be calculated from this same far-field
data, but their validity and applicability have not been established.
1.2 The measurement method is valid over a frequency range of 30 MHz to 1.5 GHz. These limits are not exact, but are based
on decreasing displacement current as a result of decreased capacitive coupling at lower frequencies and on overmoding (excitation
of modes other than the transverse electromagnetic mode (TEM)) at higher frequencies for the size of specimen holder described
in this test method. Any Select any number of discrete frequencies may be selected within this range. For electrically thin, isotropic
materials with frequency independent electrical properties of conductivity, permittivity, and permeability, measurements may will
possibly be needed at only a few frequencies as the far-field SE values will be independent of frequency. If the material is not
electrically thin or if any of the parameters vary with frequency, measurements should be made at manymake measurements at
several frequencies within the band of interest.
1.3 This test method is not applicable to cables or connectors.
1.4 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this
standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
4
2.1 ASTM Standards:
D1711 Terminology Relating to Electrical Insulation
3. Terminology
3.1 Definitions—For definitions of terms used in this test method, refer to Terminology D1711.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 dynamic range (DR), n—difference between the maximum and minimum signals measurable by the system.
3.2.1.1 Discussion—
1
This test method is under the jurisdiction of ASTM Committee D09 on Electrical and Electronic Insulating Materials and is the direct responsibility of Subcommittee
D09.12 on Electrical Tests.
Current edition approved May 1, 2010May 1, 2018. Published June 2010May 2018. Originally approved in 1989. Last previous edition approved in 19992010 as
D 4935–99.D4935 – 10. DOI: 10.1520/D4935–10.10.1520/D4935-18.
2
Wilson, P. F., and Ma, M. T., “A Study of Techniques for Measuring the Electromagnetic Shielding Effectiveness of Materials,” NBS Technical Note 1095, May 1986.
3
Adams, J. W., and Vanzura, E. J., “Shielding Effectiveness Measurements of Plastics,” NBSIR 85-3035, January 1986.
4
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
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D4935 − 18
Measurement of materials with good SE require extra care to avoid contamination of extremely low power or voltage values by
unwanted signals from leakage paths.
1
3.2.2 electrically thin, adj—thickness of the specimen is much smaller (< ⁄100) than the electrical wavelength within the
specimen.
3.2.3 far field, n—that regio
...
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