Radio Waves

Recently I heard about another group of people who were opposing the building of a mobile phone tower near to a school. I accept that most people who raise objections like this do it for the best reasons, usually concerns over the health of their children, but unfortunately these concerns are often due to a lack of understanding.

Before I continue, let me say that although I am a qualified radio engineer, I don't work in the mobile phone industry. Don't dismiss what I say as being propaganda, it's not. It can all be substantiated by reading a good radio textbook.

The towers that cause so much concern are called base stations, also known as cell sites. They communicate with your mobile phone using radio signals, providing a link between your phone and the telephone exchanges.

One of the problems is the emotive language used by the media. Instead of referring to radio signals, they often speak about radiation. Whilst this is technically correct, its scares the hell out of people who only associate radiation with atom bombs and nuclear power stations. Radio signals are a form of electromagnetic waves. Although radio waves usually have to be generated artificially, other forms of electromagnetic waves occur naturally.....you know them as HEAT and LIGHT.

Suddenly, radio waves become less scary!

It is a fact that, like light, the further a radio wave travels the weaker it gets. It's called the inverse square law, which means if the distance doubles, the intensity reduces to a quarter.

Sticking with the light analogy, consider a lighthouse. We put a lamp high up a tower, then focus the light into a narrow beam. Why? To make the light travel the greatest distance of course!

We do exactly the same with radio transmitters, but instead of lenses we use aerials.

If you stand at the base of a lighthouse, are you bathed in light? No, of course not! There' s no point in wasting energy illuminating the ground beneath.

The same is true for radio transmitters.

Just for a minute, let's suppose that there might be a risk, however small, from exposure to RF energy from cellphones......

For the reasons I've explained above, a mobile phone user will receive a much higher concentration of radio waves (what engineers call field strength) from the phone held against his head, than he would from being near a base station tower.

Many of these protesters are quite happy to let their little ones have mobile phones. If that's OK, why do they consider the masts to be dangerous?

The fact is, having a base station on a school building is actually a good idea!

All mobile phones reduce their transmitter power as they get nearer to the base station. They do this to reduce the drain on the battery, so you can talk for longer. Having a base station on the roof of a school won't harm anybody nearby, but it would ensure that all the children's phones are operating at the lowest possible transmitter power.

And even though there is still no scientific evidence of risk, there's certainly no harm in reducing our children's exposure.