Numerous factors affect the range of FRS & GMRS radios.  

 

  • FRS and GMRS radios operate in the UHF band (Ultra High Frequency) between 400-520MHz.  FRS and GMRS radio signals travel in straight lines (called “line-of-sight” signals) and generally cannot travel beyond the horizon without one or both of the radios being at a higher elevation and/or without additional equipment including repeaters to boost the signal.  This is different than CB radios that transmit at a lower frequency in the 26-27MHz HF band (High Frequency).  CB signals ‘bend’ over hills and objects more effectively than higher frequency signals and can reflect off of the ionosphere.  This reflection is called “skipping” and can cause a signal to propagate hundreds or even over a thousand miles.

 

FRS and GMRS range can be maximized by:

  • Using a radio with a high power output.
    • FRS radios are limited to 2W maximum
    • GMRS handheld radios can operate up to 5W on Channels 1-7
    • GMRS Mobile radios, repeaters, and base stations can operate up to 50W on channels 15-22
  • Operating with batteries on a full charge
  • Orienting the radio antenna so it points vertically
  • Transmitting outdoors
  • Transmitting in open terrain
  • Transmitting or receiving from a high elevation point
  • Using an antenna with positive gain to strengthen the radio signal (GMRS only)
  • Using a GMRS mobile radio that is installed in a vehicle or as a base station.  GMRS Mobile radios can be up to 50W and the antennas are more efficient than those on handheld radios

 

Range will be reduced by:

  • Operating with batteries that are low on charge
  • Transmitting in terrain (woods, forests, hills, city buildings).  Denser obstructions like high-rise buildings in a city will greatly restrict the range
  • Operating inside of a building.  Range will be further reduced if the building has a metal frame or if the building has aluminum siding
  • Transmitting or receiving from within a vehicle

 

Guidelines on Range

  • In an ideal situation with one radio operated by a person on a mountainside and another radio operated by a person in a valley below or on an adjacent mountain it is possible to get make contact at 40 miles or more even with a 0.5W or 1W radio.  If there is “line-of-sight” between the radios with one of both of the radios at elevation very long ranges can be achieved
  • With GMRS radios range can be greatly expanded through the use of repeaters.  Like a radio on the top of a mountain, repeaters are typically installed on towers that are higher than the surrounding terrain.  Using “line of sight” a radio can connect into the repeater from a wide radius around the repeater.  The repeater then retransmits the signal out at a higher power than a handheld radio.  Repeaters can be up to 50W

 

Here are some APPROXIMATE numbers on what kind of range to expect under various conditions.  Remember, these are average values.  True range will depend on actual conditions (for instance a neighborhood with tall apartment buildings will have shorter range than a neighborhood of single-story homes).

 

 

Operating Conditions                                   Approx. Range – handheld to handheld radio

 

Outside, clear flat terrain                                 1.5 – 3+ miles

 

Outside, favorable conditions                         5-10+ miles

(one or both radios at altitude)

 

Outside, ideal conditions                                30+ miles

(peak to peak or peak to valley)

 

Woodlands, moderate vegetation                  1 – 1.5+ miles

 

Woodlands, thick vegetation                          1/2 – 1+ mile


Between buildings or houses                         1/8 – 1/2 mile

 

Suburban Neighborhoods                              1 – 2+ miles

(low population density)

 

Urban Areas                                                    1/2 – 1 mile

(more/taller buildings)