The current licensing condition from Ofcom for fireground radios is a maximum of five watts of radiated power for handheld devices. Radio coverage can generally be improved by increasing radiated power, but this affects battery life.
Radio waves spread from an antenna horizontally and in a straight line, reducing in intensity by a factor of four each time the distance doubles; this is known as ‘free space path loss’. Obstructions such as hills, trees and buildings will affect the radio waves, weakening the signal.
The relationship between power output and radio propagation is complex and services should seek specialist technical advice on the subject.
When considering the power output of handheld radios fire and rescue services should be aware of the potential for health effects related to radio wave (RF) electromagnetic radiation. Risk can be reduced by factors such as the amount of time a device is transmitting and the use of remote speaker microphones. For further information see: HSE non-ionising radiation FAQs