Radio Range

The ranges quoted by the radio manufacturers are for guidance only. Actual performance will vary either side of this range.

For example PMR446 radios are often quoted as having a range of 3km

The range over which a radio link will work reliably can often be hard to predict. To quote a range without knowing the terrain is usually just a guess.

Range is dependent on many factors. The best range is achieved in open space well above ground level. Mountain-top to mountain-top is a good example. This is often referred to as 'line-of-sight'. (Don't take this literally as radios work just as well in the dark, cloud or fog!)

'Line-of-sight' range should be considered the absolute maximum range. As the two radios come nearer to ground level obstacles on the ground start to absorb some of the radio signal. Buildings, trees and ground undulations all reduce range.

In flat country, range may well be less than half line-of-sight. Absorption is worst with soil, rock and metallic structures. Avoiding these between the two radios will help improve the range.

Sometimes materials that absorb signals will also reflect them. This can be used to your advantage particularly in hill country where there maybe a ridge of high ground between the radios. Reflection from a nearby hill will sometimes bounce the signal bypassing the obstacle.

Only your own experience will help you predict where radios won't work, the following briefly sums up the situation.

• At sea or from mountaintop to mountaintop will give the best range (an exception being in a small boat in a high swell).
• In very flat country the range will be predictably average
• In hilly country the range will vary from the impressive to the disappointing.
• Underground and in metal structures range can be poor.

Relocate if range is poor. A few metres higher will often make a huge difference to range.