5.2 With Line-of-Sight
When installing the Receiver 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 the Connector/Transmitter and the
Receiver.
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
the Connector/Transmitter and Receiver.
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 Receiver and Connector/Transmitter should be perpendicular to the
plane where Receiver and Connector/Transmitter is located.
or
FRESNEL ZONE
RECEIVER
ANTENNA
END DEVICE
CONNECTOR/
TRANSMITTER
ANTENNA
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