# Electromagnetic compatibility

## ELECTROMAGNETIC COMPATIBILITY DIRECTIVE 89/336/EEC

The United Kingdom integrated the above directive into UK law in 1992 as the Electromagnetic Compatibility Regulations 1992 (Statutory Instrument (SI) 1992/2372). From the 1st January 1996 the EMC Regulations require that most electrical and electronic products made or sold in the United Kingdom, including imports must: -

- Be so constructed that they do not cause excessively electromagnetic interference and are not unduly affected by electromagnetic interference:
- In the case of certain radio-transmitting equipment, be subject to EC Type examination by a notified body; and,
- Carry CE marking

Products are defined as items with an intrinsic function intended for the end user, and supplied or intended to be supplied, or taken into service or intended to be taken into service as a single commercial unit. Products can range from simple power supplies to computers, radio transmitters, amplifiers, rotators, household white goods like microwave ovens, toasters, kettles fridge's and freezers, lawn mowers etc.

Electromagnetic disturbance (Interference) means any electromagnetic phenomenon, which may degrade the performance of apparatus (Products). This may be an unwanted signal or noise etc. Therefore, all electromagnetic frequencies are involved and are set out in the regulations.

A signal or emission which is a necessary function or a consequence of operation of applicable apparatus (products) shall not be taken as an electromagnetic disturbance if the signal or emission is permitted and does not exceed the limits specified by: -

- The applicable EMC Standard
- A condition of a technical report or certificate issued by a competent body for the purposes of a technical file (on the product).
- A condition of an EC type examination certificate issued by a notified body (in the case of radio communications transmitting equipment; or,
- A term, provision or limitation of a licence granted under section one of the Wireless Telegraphy Act 1949, or regulations made under that section of the act, or
- Where the apparatus is a transmitter or other apparatus that operates by emitting electromagnetic radiation in the radio frequency spectrum and the emission does not exceed the limits specified under section 10 of the Wireless Telegraphy Act 1949 concerning spectrum planning or European community obligations.
- Performance is degraded if permanent, temporary or intermittent function or significant impairment of function is experienced or,
- Where the apparatus is information storage or retrieval equipment, the destruction or corruption of the information stored is experienced.

For the radio amateur this means that if the equipment you use is available commercially then it must carry a "CE" mark. If you build it yourself then it does not need to be CE marked because Amateur Radio equipment (home built) is specifically excluded so long as it does not constitute any kind of commercial transaction. Citizen's band equipment is considered as consumer electronics, therefore the equipment must carry a "CE" mark.

The definition used is that "Radio amateurs are persons carrying out experimental activities within the field of Radio Communications, according to the Definition No. 53 of the International Telecommunications Union Radio communications Regulation.

To sum up the implications for the amateur, using CE marked equipment should ensure that the transmissions of unwanted electromagnetic emissions is limited to the levels set out in the applicable standards provided that the equipment is installed and maintained as the manufacturer intended it to be. The equipment also has a minimum level of immunity from other CE marked equipment so that it will operate as intended without intermittent, temporary, or permanent degradation.

It is important to note that the manufacturer of household and similar goods will not intend their equipment to be operated near high powered radio stations where the field strength may be in excess of the immunity limits of the standards applied to his equipment. In these cases the amateur may need to employ band pass and other filters on both their own and the affected equipment or even limit the field strength of their transmissions to ensure that their own or neighbours equipment performance is not unduly effected by radio spectrum transmissions.

Back | Index | Next