EMF Measurement at Height

Nigel Turner has spent most of his career as a broadcast antenna engineer and now works as an EMF safety specialist with Link Microtek. He is a Chartered Engineer, Member of the Institution of Engineering & Technology, and is secretary of SRP ' s EMFOR Committee.

What ' s up? I I have spent much of my career measuring electromagnetic fields( EMF) in high-up places, mainly TV, radio and telecoms sites. The antennas tend to be sited on towers, tall buildings, chimneys, etc. so that the signals can propagate more effectively; it also keeps them well away from the public. Like any type of radiation, too much of it can be harmful, although the effects of radio frequency radiation are very different to those of ionising radiations.

Measurement equipment typically comprises an electric and / or magnetic field probe and a display meter. Because effects on the human body vary with frequency, some probes have frequency weighting built in. Equipment is also available that can identify the frequencies in use, which can be helpful when multiple services are present.

Close to antennas, the field strength will vary considerably and sometimes unexpectedly due to interactions with anything conductive such as ladders, cables or even the human body. This can make it difficult to obtain an accurate reading.

When multiple operators( such as broadcasters and telecoms providers) share the same site, each wants the best position, so the top of these sites becomes quite congested. This inevitably means that in order to work on one system, you have to get quite close to the others. Whereas operators are keen to get the highest location, they are less keen to switch off their systems to allow others to work close to them, so there is often a need to assess the hazards.

Sometimes it is possible to assess the hazard by calculation or computer modelling, but this often cannot give the full picture or would take too long. In such cases, taking measurements can be the most practicable method.

Signage – what ' s wrong with this picture?

What could possibly go wrong? Working at height brings its own challenges before you even think about the EMF. The risk of falling is obvious; training and fallprevention / arrest devices are usually the solution. Dropped objects can also do serious harm to people below, so exclusion / drop zones and tool-tethering are widely used.

Weather is never better at height than at ground level, except maybe on a hot day when sunburn is a danger. Wind, high or low temperature, rain, snow and ice can harm people and measurement equipment.

Radiation Protection Today Spring 2025 13