User manual

WI-MOD-9-E Wireless Ethernet User Manual
WI-MOD-9-E Manual V1.9 Page 12
Line-of-sight paths are only necessary to obtain the maximum range. Obstructions will reduce
the range, however may not prevent a reliable path. A larger amount of obstruction can be
tolerated for shorter distances. For very short distances, it is possible to mount the antennas
inside buildings. An obstructed path requires testing to determine if the path will be reliable -
refer the section 6 of this manual.
In certain circumstances, much longer distances can be achieved by reducing the transmitter
power and using higher gain antennas. Although the effective radiated power at the transmitter
end is the same, the additional antenna gain at the receiver gives increased distance. This is only
true for locations of low background noise as the antenna gain will also increase the noise level.
For example, in America where 4W ERP power is permitted, a combination of 0.1W transmitter
power and 16dB antenna gain (giving 4W ERP) can give distances of more than 60 miles
(100km). However antennas will need to be elevated to give line-of-sight. This is a special
installation and advice from Weidmuller should be sought.
Where it is not possible to achieve reliable communications between two WI-I/O-9 modules,
then a third WI-I/O-9 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 a host device connected to it.
An antenna should be connected to the module via 50 ohm coaxial cable (eg RG58, RG213 or
Cellfoil) 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 to choose antennas carefully to avoid contravening the maximum
power limit on the unlicensed channel - if in doubt refer to an authorized service provider.
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 maximum net gain of the antenna/cable configuration permitted is
Country Max. gain (dB)
USA / Canada 6
Australia / New Zealand 0 for 1W transmit power
10 for 0.1W transmit power
The gains and losses of typical antennas are
Antenna Gain (dB) Antenna Gain (dB)
Dipole with integral 15’ cable 0 6 element Yagi 10
5dBi Collinear (3dBd) 5 9 element Yagi 12
8dBi Collinear (6dBd) 8 16 element Yagi 15
Cable type Length (m) Loss (dB)
CC10/900 10 3
CC20/900 20 6