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Antenna Gain
Gain is a relative measure of an antennas ability to direct or concentrate radio frequency energy in a particular direction
or pattern. Gain is typically measured in dB over Isotropic point source, dBi. The analogy of an Isotropic point source
would be a sun in the center of a universe. The choice of gain is dependent on system design, coverage, range, and
transmit power. A higher gain number is not always the best choice. Gain and antenna type must be chosen to meet all
objectives.
Antenna Installation Best Practices
Line of Sight
Whether you are installing a wireless network indoors or outdoors you must always consider line of site. The path
between two antennas is referred to as the Line of Sight. There are three main categories of Line of Sight, the first being
full Line of Sight (LOS) where no obstacles reside between the two antennas, the next is called Near Line of Sight (nLOS)
which includes partial obstructions such as tree tops or buildings between the two antennas, and lastly Non Line of Sight
(NLOS) where full obstructions exist between the two antennas. By determining the specific line of sight conditions in
the WiFi network area you can then determine the correct type of wireless system to install.
Fresnel Zone- The area around the visual line-of-sight that radio waves spread out into after they leave the antenna.
This area must be clear or else signal strength will weaken due to reflections (when wireless signals "bounce" off
objects) that cause fading (loss of the wireless signal). Trees, buildings, towers etc. in the Fresnel Zone will produce
reflections that can result in signal fading.
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