Pencil (optics)

As a Pencil Beam (English literally for " pencil - beam " ) are very strong in radio technology called bundled electromagnetic waves. There a transmit beam is so vividly described, the " thin as a pencil" is.

Antennas with a focused radio beam does have a very narrow opening angle and thus a very large gain. Pencil-beam antennas are used for example as a fire control radar. True 3D radar devices of the air defense also emit radio waves bundled.