IEC PAS 62431:2005 pdf download Measurement methods for reflectivity of electromagnetic wave absorbers in millimetre wave frequency
Scope
This PAS specifies the measurement methods for the reflectivity of electromagnetic waveabsorbers (EMA) for the normal incident, oblique incident and each polarized wave in thefrequency range from 30 GHz to 300 GHz In addition, these methods are also equallyeffective for the reflectivity measurement of other materials.
This PAS is applicable not only to those EMA which are widely used as the counter-measuresagainst communication faults, radio interference etc.. but also to those used in an anechoicchamber in some cases. EMAs may be any kind of material and may have any arbitrary shapeconfiguration,or layered structure as indicated below.
Material:Conductive material, dielectric material, magnetic materialShape:Planar,pyramidal-type,wedge-type,etc.Layer structure:Single layer, multi layers, and graded-index material
This PAS may give the measurement method of reflectivity applicable to various EMAs ormaterials. However, it may not be applicable to all EMAs.
This PAS may be supplemented with additional methods if necessary so that a future demandmay be fulfilled.
The PAS specifies the measurement methods for the reflectivity of EMA in the millimetrewave range:
measurement frequency range: 30 GHz to 300 GHz
reflectivity: 0 to -50 dB
incident angle:0to 80
2Normative references
The following referenced documents are indispensable for the application of this documentFor dated references, only the edition cited applies. For undated references, the latest editionof the referenced document (including any amendments) applies.
SO/IEC 17025，General requirements for the competence of testing and calibration/aboratories
EEE 1128,IEEE Recommended Practice for EMA evaluation in the range from 30 MHz to5 GHz
3 Terms,definitions and acronyms
3.1 Terms and definitions
For the purposes of this document, the terms and definitions of IEEE 1128, as well as thefollowing apply.
3.1.1
ambient level
value of radiation power or noise which exists when no measurement is being carried out atthe experiment site
3.1.2
dynamic rangedifference in decibels between the receiving level from a reference metal plate and thereceiving level measured when the metal plate is removed
3.1.3directional gainratio of the radiated power density in a particular direction to the average power density thatwould be radiated in all directions
3.1.4
dielectric lenselectromagnetic wave lens that is composed of dielectric material, usually mounted in front ofa pyramidal or conical horn
3.1.5
electromagnetic wave absorber
material ingredient which absorbs the electromagnetic wave energy and dissipates it thermally
3.1.6
focused beamfocused electromagnetic wave converged by the dielectric lens mounted in front of the hornantenna. The focused beam diameter is a few times the wavelength or more at the beamwaist, which depends on the focal distance of the lens
3.1.7
Fraunhofer regionThe region where the angular radiation pattern of an aperture antenna is nearly independentof the distance.
3.1.8
Fresnel region
region where the angular radiation pattern of an aperture antenna depends on the distanceexcept for the extremely near region from the aperture
3.1.9
free-space method
measurement method that employs a single or a pair of horn antennas where the specimenand the antennas are put in free space
3,1.10
horn antenna
aperture antenna where impedance matching is taken gradually from the waveguide aperture
to free space

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