Weidmuller WI-I/O-9-U2: Wireless Mesh I/O & Gateway User Manual V1.2.2 - Manual (Page 24)

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testing to determine if they are reliable - refer section 5.6
“Network Statistics” Where it
is not possible to achieve reliable communications between two modules, then a third
module may be used to receive the message and re-transmit it. This module is referred
to as a repeater. This module may also have input/output (I/O) signals connected to it
and form part of the I/O network - refer to Chapter 4 Configuration of this manual.
An antenna should be connected to the module via 50 ohm coaxial cable (e.g. RG58,
RG213, Cellfoil, etc) terminated with a male SMA coaxial connector. The higher the
antenna is mounted, the greater the transmission range will be, however as the length
of coaxial cable increases so do cable losses. For use on unlicensed frequency
channels, there are several types of antennas suitable for use. It is important antennas
are chosen carefully to avoid contravening the maximum power limit on the unlicensed
channel - if in doubt refer to your distributor.
The net gain of an antenna/cable configuration is the gain of the antenna (in dBi) less
the loss in the coaxial cable (in dB).
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 metres) of
Cellfoil cable 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 vulcanising
tape suc
h as “3M 23 tape”, and finally with another
layer of PVC UV Stabilised insulating tape. The first
layer of tape allows the joint to be easily inspected
when trouble shooting as the vulcanising 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.
Dipole and Collinear antennas.
A collinear antenna transmits the same amount of radio power in all directions - and
they are easy to install and use because they do not need to be aligned to the
destination. 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 1 wavelength
away from a wall or mast to obtain maximum range.
Figure 6 - Wrapping Coax Connections