Product Manual

Installation of Radio and Modem
47
6.4. Clear Line of Sight
Caution
There can be no obstructions in the Fresnel zone. If there are
obstructions within this broad beam or Fresnel Zone, some
of the signal is diffracted off the obstruction, with an
accompanying phase shift.
The AirPair must have a clear line of sight. Use caution and make sure there is proper Fresnel
Zone clearance. The size of the beam grows as it propagates towards the destination. The
beam must have no obstructions in its path. Obstructions within the path of the beam can
decrease the signal quality by diffracting the signal.
When you consider Fresnel Zone clearance, you must consider both the height above and the
lateral distance from obstructions Figure 13 show trees within the Fresnel zone that obstruct the
signal. Do not allow any obstruction of the Fresnel Zone.
Figure 13
WRONG! Obstruction of the Fresnel Zone
Figure 14
WRONG! Trees within the Fresnel Zone Obstruct the Signal
Fresnel Zone
Version 2.0