This article is from the Satellite TV FAQ, by Gary Bourgois flash@lopez.marquette.mi.us with numerous contributions by others.
The most common type of dish mount is called a POLAR MOUNT, so named
because it is oriented to coincide with the earth's axis, enabling
it to "track" the satellites, which are spread out in geostationary
orbit in a band of the sky called the "Clarke Belt", named after
Arthur C. Clarke, who dreamed up the concept of geostationary
communications satellites back in 1945.
The mount is installed on a 3 inch pipe, which is sunk in concrete.
Most (but not all) mounts require a 3.5" OD pole. In most (but not all)
cases this is a 3" ID pipe. Schedule 40 works well, so does used "drill
stem". In many areas, this is available from salvage dealers at very
reasonable prices. (* OD refers to OUTER DIAMETER, ID refers to
INNER DIAMETER)
 
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