EUROLAB laboratory provides testing and compliance services within the scope of ASTM D4935 standard. The ASTM D4935 standard provides a method for measuring the electromagnetic shielding efficiency of a planar material for a plane, far-field electromagnetic wave. From the measured data, near field shielding efficiency values for magnetic sources for electrically thin samples are calculated.
Electric field shielding efficiency values were also calculated from the same far field data, but its validity and applicability were not determined. The full name of this standard is as follows: ASTM D4935 Standard test method for measuring the electromagnetic shielding effectiveness of planar materials.
Measurements made within the scope of this standard are valid in the frequency range of 30 MHz to 1,5 GHz. However, these limits are not exact. This test method is based on reduced displacement current as a result of reduced capacitive coupling at lower frequencies and excessive modification at higher frequencies, i.e. excitation of modes other than the transverse electromagnetic mode, for the sample holder size described.
Any number of individual frequencies in this range should be selected during the tests. For electrically thin, isotropic materials, far-field shielding efficiency values for frequency-independent electrical conductivity and permittivity properties are frequency-independent. Therefore, measurements are only required at a few frequencies. If the material is not electrically thin or if any of the parameters change with frequency, measurements should be made at several frequencies within the baseband.
The test method presented in this standard does not apply to cables or connectors. Briefly, this test method is applicable to measure the shielding efficiency of planar materials under normal field, far field and plane wave conditions.
The uncertainty of the measured shielding efficiency values is a function of the mismatches in the material's transmission line path, the dynamic range of the measuring system, and the accuracy of the auxiliary equipment. An uncertainty analysis is included in the standard appendix to illustrate the probability of uncertainty obtained by an experienced user using good equipment. Deviations from processes in this test method increase this uncertainty.
This test method measures the net shielding efficiency value caused by reflection and absorption. Measurement of reflected and absorbed power is accomplished by adding a calibrated bidirectional coupler to the inlet of the gripper.
ASTM D4935 shielding effectiveness testing focuses on planar materials. However, this standard does not claim to address all safety concerns for use. It is the responsibility of the implementer of this standard to establish appropriate safety and health practices and to determine the applicability of regulatory restrictions prior to use.
Dynamic range refers to the difference between the highest and lowest signals measured by the system according to the ASTM D4935 standard. The term electrically thin means that the thickness of the sample is much smaller than the electrical wavelength in the sample. The far field is the region where the vectors are perpendicular to each other and both are perpendicular to the direction of propagation of energy. The near field is the region where vectors are not associated with simple rules. Ultimately, shielding efficiency is the ratio of the power received with and without a material for the same incident force.
In many applications, the shielding efficiency values of the materials expand to frequencies well above 1 GHz with the effect of higher frequencies. In addition, energy efficiency requirements require the use of lightweight shielding materials such as composites, especially in aerospace applications. A typical concern with composite materials is their internal homogeneity.
Our organization, EUROLAB, provides standard test method services to measure the electromagnetic shielding efficiency of planar materials, within the framework of national and international standards, with its trained and expert staff and advanced technological equipment, among numerous test, measurement, analysis and evaluation studies. Provides testing services within the scope of ASTM D4935 standard.
To get an appointment, to get more detailed information or to request an evaluation, you can ask us to fill in our form and reach you.
EUROLABreporting and certification activities, United Accreditation Foundation (UAF), Turkish Accreditation Agency (TÜRKAK) ve Enterprise Accreditation Foundation (EAF) based on the accreditation provided by the accreditation body. The Enterprise Accreditation Foundation (EAF) accreditation body is also a signatory of the United Nations (UN GLOBAL COMPACT) organization.
