Tropospheric scatter (or troposcatter) is the scattering of distant TV and FM radio stations by the troposphere so that they travel farther than the line of sight. This effect sometimes allows reception of stations up to a hundred miles away.

The phenomenon has been used to build communication links in a number of parts of the world. Large billboard antennas focus a high power radio beam at the troposphere mid-way between the transmitter and receiver. A certain proportion of the signal is refracted and received at a similar antenna at the receiving station.

One such link operated between the North of Scotland, at Mormond Hill and the Shetland Isles.

The U.S. Army uses tactical tropospheric scatter systems developed by Raytheon for long haul communications. The systems come in two configurations, the original "heavy tropo", and a newer "light tropo" configuration exist. The systems provide four multiplexed group channels and trunk encryption, and 16 or 32 local analog phone extensions.

The U.S. Marine Corps also uses the same device, albeit an older version.

See also

• Radio propagation
• Microwave
• ACE High - Cold war era NATO European troposcatter network
• White Alice Communications System - Cold war era Alaskan tropospheric communications link
• List of White Alice Communications System sites
• TV-FM DX

External links

• DART-T
• Russian tropospheric relay communication network
• FS-1037C definition of tropospheric scatter
• Troposcatter communication network maps