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The Epic Interactive Encyclopedia 1997
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The_Epic_Interactive_Encyclopedia_97.iso
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aerial
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1992-09-02
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643b
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17 lines
Aerial, or antenna
In radio and television broadcasting, a
conducting device that radiates or receives
electromagnetic waves. The design of an
aerial depends principally on the wavelength
of the signal. Long waves (hundreds of metres
in wavelength) may employ long wire aerials;
short waves (several centimetres in
wavelength) may employ rods and dipoles;
microwaves may also use dipoles - often with
reflectors arranged like a toast rack - or
highly directional parabolic dish aerials.
Because microwaves travel in straight lines,
giving line-of-sight communication, microwave
aerials are usually located at the tops of
tall masts or towers.