User manual

Chapter Two Installation
Page 13 March 2010
The net gain of the antenna/cable configuration is determined by adding the antenna gain and the
cable loss. For example, a 6 element Yagi with 70 feet (20 meters) of Cellfoil has a net gain of
4dB (10dB – 6dB).
Connections between the antenna and coaxial cable should be carefully taped to prevent ingress
of moisture. Moisture ingress in the coaxial cable is a common cause for problems with radio
systems, as it greatly increases the radio losses. We recommend that the connection be taped,
firstly with a layer of PVC Tape, then with a vulcanizing tape such as “3M 23 tape”, and finally
with another layer of PVC UV Stabilized insulating tape. The first layer of tape allows the joint
to be easily inspected when trouble shooting as the vulcanizing seal can be easily removed.
Where antennas are mounted on elevated masts, the masts should be effectively earthed to avoid
lightning surges. For high lightning risk areas, surge suppression devices between the module
and the antenna are recommended. If the antenna is not already shielded from lightning strike by
an adjacent earthed structure, a lightning rod may be installed above the antenna to provide
shielding.
2.2.1 Dipole and Collinear antennas.
A collinear antenna transmits the same amount of radio power in all directions - as such that are
easy to install and use. The dipole antenna with integral 15 ‘cable does not require any additional
coaxial cable, however a cable must be used with the collinear antennas.
Collinear and dipole antennas should be mounted vertically, preferably 3 feet (1 meter) away
from a wall or mast to obtain maximum range.
1m minimum
COLINEAR
ANTENNA
MAST
EARTH STAKE
IF GROUND CONDITIONS ARE
POOR, INSTALL MORE THAN
ONE STAKE
INSTALL AERIAL ABOVE
LOCAL OBSTRUCTIONS
ANT
WI
-
MOD
SURGE
ARRESTOR
(OPTIONAL)
COAXIAL CABLE
WEATHERPROOF
CONNECTORS WITH
“3M 23” TAPE
STRESS RELIEF LOOP
PROVIDE GOOD
GROUND
CONNECTION TO
MAST, MODULE
AND SURGE
ARRESTOR
GND