User manual

Chapter 3 Installation
Page 29 ©February 2009
Where antennas are mounted on elevated masts, the masts should be effectively earthed to avoid
lightning surges. The 220MHz and 400 – 500MHz radios are fitted with surge protection,
however the 868MHz radio does not.
For high lightning risk areas, additional 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 should be installed above the antenna to provide
shielding.
3.2.1 Dipole and Collinear antennas.
A collinear antenna transmits the same amount of radio power in all directions - it is easy to
install and use. The dipole antenna with integral 5m cable does not require any additional
coaxial cable, however the other collinear antennas do not have integral cable and an external
cable length must be connected - such as the CC10 or CC20 cable kits.
Collinear and dipole antennas should be mounted vertically, preferably no less than 0.6 metre
away from a wall or mast to obtain maximum range.
3.2.2 Yagi antennas.
A Yagi antenna provides high gain in the forward direction, but lower gain in other directions.
This may be used to compensate for coaxial cable loss for installations with marginal radio path.
1m minimum
COLINEAR
ANTENNA
MAST
EARTH STAKE
IF GROUND CONDITIONS ARE
POOR, INSTALL MORE THAN
INSTALL AERIAL ABOVE
LOCAL OBSTRUCTIONS
ANT
Module
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
for best performance