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**Understanding Radio Range Claims

The 16 Mile Motorola 2-way radio The 20 Mile Motorola 2-way radio The 27 Mile Motorola 2-way radio

Two-way radios that use the Family Radio Service (FRS) and General Mobile Radio Service (GMRS) frequencies maintain specific range claims, which can prove confusing for consumers.  The Motorola Talkabout® Radio range claims are based on, and verified by, independent field surveys.  To comprehend these independent claims it helps to understand the theory of radio wave propagation and the engineering constraints and subsequent compromises taken when designing radios. 

Radio waves emanate in concentric circles and lose power inversely exponentially the further they travel from the source.  For example, when the distance from the radio is doubled the power of its signal is only one eighth of its original strength.  Additionally, radio waves are negatively influenced by conductive materials, which reflect the waves while absorbing some of its energy.  Conductive materials include metal, buildings or other man-made structures.  Natural structures are non-conductive and force the radio waves to go around them, thereby altering the path of concentric rings and preventing the signal from reaching the receiver.

Even the curved surface of the Earth is a limiting factor for radio signal range.  On exactly flat terrain the horizon as seen by a six foot tall person is approximately 3.5 miles away.  Similar to the line of sight to the horizon, the radio signals travel in a straight path from the transmitter and do not conform to the Earth’s curvature.  If two transmitters are 6 feet off the ground, as they get further than 7 miles apart, the curvature of the earth blocks the path halfway between them.

Enhancing Range

Things to do to improve your two-way radio range:

  • Elevate your radio – the higher your radio the more likely you will transmit over terrain and obstructions, therefore move up hill or use your headset and hold the radio above your body.
  • Use a hill as a reflector – stand on the side of the hill facing the direction you wish to talk to.  Standing slightly below the top of the hill in the correct direction will enhance the signal away from the hill.
  • Move outside metal structures – get out of your car or building they block and therefore contain your radio signal.  Note that many glass tinting materials contain metal and therefore block radio waves. 
  • Reflect your signal – stand in front of metal objects such as your car, it can act as a kind of collector for radio signals.
  • Choose an unused channel – The interference eliminator (CTCSS and CDCSS) settings will “hide” the other signals from your receiver, but the monitor function will temporarily override the interference eliminator function, revealing all channel users.  If you attempt to use a channel when someone else is, regardless of any interference eliminator settings, neither you nor your group will have the best range, as you will be talking over each other.
  • Keep your batteries fresh.