Kipp & Zonen LAS, Instruction Manual

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APPENDIX 3 – MOUNTING ANTENNAS
Warning : Do not install antennas near power lines. Serious electrocution hazard exists. You
can be killed!
The supplied antenna for the radio modem at the
LAS receiver side is a 16 dBi Vagi-type (2.4 GHz
system) directional antenna, specifically designed to transmit in one particular direction allowing long
range applications. The antennas can be mounted horizontally (horizontal polarization) or vertically
(vertical polarization) (see Figure 34). To have radio communication both antennas must have the
same polarization (in general vertically)!
Figure 34: Vagi in horizontal polarization (left) and in vertical polarization (right).
The antennas come with a standard N-female connector and can be connected to one end of the
supplied 5 m antenna cable (N-male at both sides). The other end has to be connected to the gas
discharge surge protector (N-female to N-female). The surge protector is an integral part of the
antenna installation to protect the radio modem from surges caused by lightning. The surge protector
has the ability to withstand multiple lightning strikes. Finally, using the N-male to RSPMA-male adapter
the RF modem can be connected. Note that due to power loss the antenna cable cannot be extended
to any desired length (use special coaxial 50 Ohm antenna cable with excellent electrical and
mechanical properties).
To mount the antenna at the
LAS receiver side a universal antenna mounting system is supplied.
This mounting system allows the user a large variety of installation options for many different sites.
Important : During assembly and mounting avoid impact to antenna elements. Element
breakage could occur!
In order to have a reliable RF communication link it is highly recommended to consider the following
issues:
•
The line-of-sight RF communication path must be clear of obstructions. For example buildings
and trees will decrease the communication range. If the antenna’s are mounted too close to
the ground too much of the Freznel zone will be obstructed by the earth (see Figure 35 and
Table 5). To avoid this problem the antennas should be mounted high enough of the ground.
As the RF link is longer (> 1km) these aforementioned issues become more important. We
recommend to use a LAS – weather station set-up according to Figure 3, where the LAS is
installed at a higher level than the weather station, creating an ideal RF communication link
with low interference of ground on the Freznel zone.
•
The supplied antennas are 16 dBi directional antennas specially designed for long-range
applications. Directional antennas in line-of-sight set-ups must be precisely aimed (aligned)
and properly fixed to avoid communication problems during strong winds and the presence of
birds.