FM broadcasting
VHF Radio waves do not travel far beyond the visual horizon, so reception distances for FM stations are usually limited to 30–40 miles (50–65 km) They can also be blocked by hills or buildings.
Radio Feltham
In November 2004, Radio Feltham celebrated its 10-year broadcasting milestone by switching its transmitters from 999AM to 87.8FM. The station, run by young prisoners aged 15 to 21, expanded its usual in-house broadcast to offer a community service of music, news and information to Feltham, to a potential audience of one million residents within a 10 mile radius of HMP Feltham.