VHF radio frequencies have such a precise area of broadcast because the ionosphere does not usually reflect the signal far beyond its immediate surroundings. VHF communication is thus optimal for reaching a target in close vicinity without interfering with broadcasts with a wider scope. A disadvantage of VHF is that it is susceptible to being blocked by land features. Unlike their UHF frequency counterparts, however, VHF users don`t have to be concerned with signals being obscured by buildings or tarnished by naturalistic sounds in the atmosphere or by conflicting signals from nearby equipment.
At the lower end of the megahertz range, VHF radio frequency assignments are two-way land mobile communication; military communication that can be intercepted in vehicles or on planes; walkie-talkies, cordless phones and radio-controlled toys. The 50 to 54 megahertz range serves amateur ham radio`s 6-meter band, used largely to test frequencies. The next grouping contains what is known throughout the world as television's "band one." Although initially establishing channels two to six, with the advent of digital television, some of its channels will fall in this range depending on the area. Then, at around 108 megahertz, are the air traffic stations, meteorological satellites and FM radio`s band two, which covers both commercial and public programming.
Starting at 144 to148 megahertz is amateur ham radio`s band two; fixed mobile phones and television and radio satellite; marine radio; railway frequencies; and weather stations. Also in play is the Multi-Use Radio Service range in the VHF spectrum, originally designated for temporary licensing for businesses as long as the user kept their power at two watts. This was overturned by the Federal Communications Commission (FCC) in 2002, ruling this consideration be based on the power output of the user`s transmitter. There is a band three of television channels, a section designed for wireless microphones at precise frequencies, another layer of armature ham radio space, military aircraft radio and radio AM stations. Another use is the study of radio astronomy, the practice of tracking and observing celestial bodies from the radio frequencies they emit, but the frequencies reserved for this are confidential.
Cases of unlicensed use of the VHF frequencies (pirate radio) have a long history and are in some countries legal, with users "micro-broadcasting" without fear of consequence for transmitting without documentation and permission.
The FCC declared that all television programming would be switched to digital technology in 2009, announcing that this will allow system operators to consolidate the information that was being broadcast for television and free up frequency. The FCC has mentioned selling this newly freed VHF space to corporations, most notably wireless phone companies.