Editing General Mobile Radio Service (section)

==Range==
As with other UHF radio services, reliable range is considered to be [[Line-of-sight propagation|line-of-sight]] and the distance to the [[Line-of-sight propagation#Radio horizon|radio horizon]] can be estimated based on antenna height. Theoretically, the range between two hand-held units on flat ground would be about one or two miles (about 1.5–3 km). Mobile units might have a slightly farther range when mounted on a car roof. A GMRS repeater with an antenna mounted high above the surrounding terrain can extend the usable range to 20 miles or more (30+ km) depending on height. <ref>{{cite book |first=H. Ward |last=Silver |title=Two-way radios & scanners for dummies |publisher=For Dummies |year=2005 |isbn=0-7645-9582-2 |page=56}}</ref> Obstructions such as hills, trees, and buildings will reduce range. Higher power does not give much increase in range although it may improve the reliability of communication at the limits of line-of-sight distance.