IEC 61000-4-21 pdf download

IEC 61000-4-21 pdf download.Electromagnetic compatibility (EMC) – Part 4-21: Testing and measurement techniques – Reverberation chamber test methods
1 Scope
This part of IEC 61 000 considers tests of immunity and intentional or unintentional emissions for electric and/or electronic equipment and tests of screening effectiveness in reverberation chambers. It establishes the required test procedures for performing such tests. Only radiated phenomena are considered. The objective of this part is to establish a common reference for using reverberation chambers to evaluate the performance of electric and electronic equipment when subjected to radio-frequency electromagnetic fields and for determining the levels of radio-frequency radiation emitted from electric and electronic equipment. NOTE Test methods are defined in this part for measuring the effect of electromagnetic radiation on equipment and the electromagnetic emissions from equipment concerned. The simulation and measurement of electromagnetic radiation is not adequate for quantitative determination of effects. The defined test methods are organized with the aim to establish adequate reproducibility and repeatability of test results and qualitative analysis of effects. This part of IEC 61 000 does not intend to specify the tests to be applied to a particular apparatus or system. Its main aim is to give a general basic reference to all concerned product committees of the IEC. The product committees should select emission limits and test methods in consultation with CISPR. The product committees remain responsible for the appropriate choice of the immunity tests and the immunity test limits to be applied to their equipment. Other methods, such as those covered in IEC 61 000-4-3, CISPR 1 6-2-3 and CISPR 1 6-2-4 may be used.
3 Terms, definitions and abbreviations
3.1 Terms and definitions For the purposes of this document, the following terms and definitions together with those in IEC 60050(1 61 ) apply. 3.1 .1 antenna that part of a radio transmitting or receiving system which is designed to provide the required coupling between a transmitter or a receiver and the medium in which the radio wave propagates [IEC 60050-71 2:1 992, 71 2-01 -01 ] NOTE For the purpose of this procedure, antennas are assumed to have an efficiency of 75 % or greater. 3.1 .2 electromagnetic wave EM wave wave characterized by the propagation of a time-varying electromagnetic field and caused by acceleration of electric charges [IEC 60050-705:1 995, 705-01 -09, modified] 3.1 .3 far field region that region of the electromagnetic field of an antenna or unintentional radiator wherein the predominant components of the field are those which represent a propagation of energy and wherein the angular field distribution is essentially independent of the distance from the antenna NOTE 1 In the far field region, all the components of the electromagnetic field decrease in inverse proportion to the distance from the antenna. NOTE 2 For a broadside antenna having a maximum overall dimension, D, which is large compared to the wave- length, λ , the far field region is commonly taken to exist at distances greater than λ 2 2D from the antenna in the direction of maximum radiation. [IEC 60050-71 2:1 992, 71 2-02-02] the region far from a source or aperture where the radiation pattern does not vary with distance from the source [IEC 60050-731 :1 991 , 731 -03-92]3.1 .4 field strength magnitude of the electromagnetic field created at a given point by a radio transmitting system operating at a specified characteristic frequency with specified installation and modulation conditions [IEC 60050-705:1 995, 705-08-31 ] 3.1 .5 polarization property of a sinusoidal electromagnetic wave or field vector defined at a fixed point in space by the direction of the electric field strength vector or of any specified field vector; when this direction varies with time, the property may be characterized by the locus described by the extremity of the considered field vector [IEC 60050-726:1 982, 726-04-01 ] 3.1 .6 reverberation chamber room specially designed to have a very long reverberation time [IEC 60050-723:1 997, 723-03-30] (reverberation room) room having a long reverberation time, especially designed to make the field therein as diffuse as possible NOTE 1 The room consists of a shielded enclosure that is generally equipped with mechanical tuners/stirrers that change (stir) the boundary conditions within the enclosure and, thus, alter the structure of the electromagnetic fields within the enclosure. [IEC 60050-801 :1 994, 801 -31 -1 3, modified] NOTE 2 Reverberation rooms are used in particular for the measurement of absorption coefficients of materials and measurement of the power emitted by intentional or unintentional radiating sources. NOTE 3 Testing in a reverberation chamber can be described as a stochastic process in which the mechanical tuners/stirrers “stir” the “modes” inside the enclosure. Therefore, such chambers is also called stirred-mode, mode- stirred or mode-tuned chamber.