document updated 14 years ago, on Jan 25, 2010

There are three main types of antennas:

omnidirectional antennas (AKA an "omni") — 360° coverage [in the horizontal plane]
directional antenna — an antenna designed to radiate mainly in one direction. They're especially good for fixed point-to-point communication.
sector antennas — something in between directional and omnis; designed to be somewhat directional, but not point-to-point