Directional antennas come in many different styles and shapes. This type of
antenna does not offer any added power to the signal, and instead simply
redirects the energy it received from the transmitter. By redirecting this
energy, it has the effect of providing more energy in one direction, and less
energy in all other directions
. As the gain of
a directional antenna increases, the angle of radiation usually decreases,
providing a greater coverage distance, but with a reduced coverage angle.
Directional antennas include Yagis, patch antennas, and parabolic dishes.
Parabolic dishes have a very narrow RF energy path and the installer must be
accurate in aiming these at each other.
The Cisco directional antennas
are shown in Figure
.