DIN EN 61000-4-21:2011-12

This standard contains the German version of the second edition (2011) of the European Standard EN 61000-4-21 and is identical to the second edition (2011) of the International Standard IEC 61000-4-21 which is referred to as the basic standard. It describes the emissions measurements, immunity testing of electric and electronic equipment in reverberation chambers with regard to radio-frequency electromagnetic fields and tests of screening effectiveness of screening materials, cables and gaskets. Reverberation chambers are equipped with mechanical stirrers or tuners, which are gradually (mode-tuned operation) or continuously (mode-stirred operation) rotated and change the modes of the chambers and, as a result, the modes of the fields by their rotary motions. An overview over such chambers is given in Annex A of this standard, which also refers to the theory of cavity resonators and contains statements on tuner effectiveness and statistics of the values measured in reverberation chambers. Tests in reverberation chambers are applicable for both very low and very high field strength levels. Due to the high attenuation of the chamber with respect to the external environment, both emissions measurement and immunity testing can be carried out without limitations for most business applications. The frequency range of the tests which can be carried out in reverberation chambers is determined by the dimensions and design of the chamber as well as effectiveness of the mechanical tuner(s)/stirrer(s). Chambers having sizes of a room (screened in the usual manner) (for example, capacities between 70 m³ and 100 m³) can be typically operated without limitations within a range of 200 MHz and 18 GHz. Reverberation chambers having larger dimensions than a room (screened in a usual manner) are necessary for lower frequencies below 200 MHz. IEC currently specifies a maximum difference of 80 MHz between radiated immunity and conducted disturbance tests. This standard gives the required test equipment, specifications for chamber validation for the two operational modes - mode-tuned operation or continuous operation of the stirrer/tuner - have been made and the methods to be applied for the individual measurements are described in corresponding annexes. With respect to the previous edition, the term "calibration" has been changed into "validation", amongst others. Moreover, specifications for the use and performance of E-field probes in reverberation rooms have been added to clause 8. In Annex A, additional guidance and clarifications on the use of reverberation chambers at relatively low frequencies of operation (that is, close to the lowest usable frequency of a given chamber) were given, and the implications on the estimation of field uncertainty are outlined. Guidelines on cable-layout have been added. In Annex B, symmetric location of the field probes when the chamber exhibits cylindrical symmetry has been disallowed as such placement could otherwise yield a false indication of field uniformity and chamber performance at different locations. The difference between start frequency for chamber validation and lowest test frequency has been clarified. The tuner sequencing for chamber validation and testing is now specified to be equal in both cases. In Annex D, a requirement for the EUT and equipment not to occupy more than 8 % of the total chamber volume in immunity testing has been added. The maximum number of frequency points and the formula to calculate these points have been generalized. A mandatory specification for including the measurement equipment, test plan and cable layout in the test report has been added to resolve any dispute in case of discrepancies, particularly for low-frequency immunity testing. An informative Annex K for treatment of the measurement uncertainty during chamber validation and EMC measurements has also been incorporated and various other individual modifications have been made at various places in the standard. The responsible committee is GAK 767.3/4.4 "TEM-Wellenleiter und Reverb-Chamber" under the umbrella of Subcommittee UK 767.3 "Hochfrequente Störgrößen" ("High frequency disturbances") of the DKE (German Commission for Electrical, Electronic and Information Technologies) at DIN and VDE.