Hi Friends,

The distance two way radios broadcast is determined by radio power (measured in watts), antenna height and environmental factors.

Generally speaking more wattage means more distance. Hand held two-way radios have between 1 – 5 watts. Mobile radios, the kind you might find in a fleet of delivery trucks, broadcast between 25 -100 watts.

A general rule is to expect a 1 watt radio on flat land to provide about 1 mile of coverage. Doubling the power increases the range by about a third. A 2 watt radio on flat land provides about 1.3 miles of coverage. A four watt radio broadcasts about 2 miles.

The need for power is negated by the height of the broadcasting antenna. It does not take much power if there is little between the sending and receiving radios. For example the radios that the astronauts used on the moon to successfully talk to earth had less than 1 watt. This is because there is nothing between the moon and earth to block the signal. In effect the height of the Moon acted as an antenna.

The third factor in determining distance is the broadcast environment. If a radio signal is blocked by buildings, electrical interference, trees or mountains the signal will not reach the receiving radio.

A combination of power and antenna height solve most of these problems.

You may have seen radios at a discount store or the local sporting goods store advertising radios with talk distances of 10 miles or 12 miles or 18 miles. This is purely bogus. If bogus sounds too harsh to you, just ask the seller to demonstrate the advertised coverage. He will not be able to do it.