Omega Vehicle Security Wireless Sensor System zSeries User Manual
Page 66
5.2 With Line-of-Sight
When installing your Coordinator it is important to position your device in such a way to
optimize the antenna location within what’s known as the "Fresnel Zone". The Fresnel
Zone can be thought of as a football-shaped invisible tunnel between two locations that
provides a path for RF signals between your End Device and your Coordinator.
Figure 5.2 Fresnel Zone
In order to achieve maximum range, the football-shaped path in which radio waves travel
must be free of obstructions. Obstacles in the path (especially metal) will decrease the
communication range between your End Device and Coordinator. Also, if the antennas
are mounted just barely off the ground or below the ceiling, over half of the Fresnel zone
ends up being obstructed resulting in significant reduction in range. Below is the
calculated radius of the football-shaped tunnel for different distance range:
Distance (feet)
Radius (feet)
100
3.2
200
4.5
300
5.5
It is recommended that within the tunnel of the above radius, at least 60% of space is
free of obstruction.
Since signal reaches destination directly in a line-of-sight situation, it is important to
adjust antenna properly to achieve maximum performance. Antenna for the Coordinator
and End Device should be perpendicular to the plane where Coordinator and End
Device is located.
60