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AGRI-ALERT WIRELESS MODULE
AGRI-ALERT WIRELESS MODULE rev.04
4.2.2.2 Antenna Height
The height of an antenna basically depends of the following factors:
Distance Between Buildings:
The longer the link, the higher the antenna needs to be.
Line of Sight (LOS) & RF Path:
All antennas must be mounted in order to have a
direct line of sight with the antenna of the master module. This direct line of sight is
only possible when all antennas have about the same height above mean-sea-level. In
addition, the area around the visual line of sight – the RF path – must be clear from
obstacle or else signal strength will be degraded.
Antenna Height & RF Path Clearance:
The height of the antennas must ensure a complete clearance of the RF Path. This
path has an elleptical shape and is defined based on the greater distance that separates
any two buildings on site. Take the greater distance between two buildings and then
refer to the table in Appendix A at the end of this manual to see what RF clearance
must be respected. This clearance must be present at the midway point between the
buildings, above and below the line of sight (see picture above). Determine the antenna
height accordingly.
PRECAUTIONS:
Do not install the antenna higher than recommended unless
immovable objects are in the RF path. Support cables may
also be required to fix the antenna pole in place.
The antenna height must not exceed 4 feet above the
roof peak; otherwise, it may become a target for lightning.
If you are unable to meet the recommended antenna height
requirement, please get professional help.
Figure 14 RF Path
