Measurements in electromagnetic compatibility

Electromagnetic compatibility (EMC) has taken on considerable importance in recent years, with the obligations arising from the application since 1 ^er January 1996 of the European EMC Directive (89336/EEC) transposed into French law by Decrees 92-587 and 95-283 of the Journal Officiel.

This directive was repealed on July 20, 2007 and replaced by a new one, entitled 2004/108/CE, published on December 15, 2004. It was transcribed by Decree 2006-1278 of October 18, 2006.

What is EMC? What implications does the European directive have? The directive stipulates that equipment placed on the European market must be designed and manufactured, in accordance with the state of the art, in such a way as to guarantee :

• the electromagnetic disturbance produced does not exceed the level beyond which radio and telecommunications equipment or other equipment cannot operate as intended;

• they possess a level of immunity to electromagnetic disturbance to be expected in the context of their intended use, enabling them to operate without unacceptable degradation of that use.

With regard to the first condition, the aim is to limit the risks of interference between radio systems (radio transmitters/receivers), to characterize radio emissions from transmitters and the effects of their radiation, to identify and limit the disruptive power of non-radio equipment that may interfere with the reception of radio systems or disturb the operation of other nearby equipment, ensure the cleanliness of 50 Hz network supply signals by limiting the amplitude of 50 Hz harmonics fed back into supply networks and all associated signals, avoid the coupling by telecommunications or supply networks of signals from powerful radiocommunications or broadcasting transmitters, etc.

The second condition entails the need to identify, characterize and therefore measure the disturbances emitted by the devices, as well as the disturbances that may affect them.

The aim of this article is therefore to characterize measurement methods in electromagnetic compatibility, both in one direction (disturbances produced by equipment) and in the opposite direction (disturbances acting on equipment). This article will only refer to harmonized civil standards (CENELEC, IEC and CISPR) and will not cover measurement methods developed within the framework of French (GAM) or American (MIL) military specifications. However, a large number of methods used by military authorities and based on signals of the same nature to be measured, are similar in principle, although not identical in test methodology and measurement interpretations....