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Broadcast TV Problem
Conceptually, satellite television is a lot like broadcast
television. It's a wireless system for delivering television programming
directly to a viewer's house. Both broadcast television and satellite
stations transmit programming via a radio signal (see How Radio
Works for information about radio broadcasting).
Broadcast stations use a powerful antenna to transmit radio waves
to the surrounding area. Viewers can pick up the signal with a much
smaller antenna. The main limitation of broadcast television is
range. The radio signals used to broadcast television shoot out
from the broadcast antenna in a straight line. In order to receive
these signals, you have to be in the direct "line of sight"
of the antenna. Small obstacles like trees or small buildings aren't
a problem; but a big obstacle, such as the Earth, will reflect these
radio waves.
If the Earth were perfectly flat, you could pick up broadcast television
thousands of miles from the source. But because the planet is curved,
it eventually breaks the signal's line of site. The other problem
with broadcast television is that the signal is often distorted
even in the viewing area. To get a perfectly clear signal like you
find on cable, you have to be pretty close to the broadcast antenna
without too many obstacles in the way.
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