WI-I/O 9-K
v1.9
Page 24
connect to an earthed surface. If this is not possible, use an earth lug in the mounting screw
connection and secure the other end of the wire to a good earth.
3.2
Antenna Installation
The WI-I/O K module will operate reliably over large distances. The distance which may be
reliably achieved will vary with each application - depending on the type and location of
antennas, the degree of radio interference, and obstructions (such as hills or trees) to the radio
path. Typical reliable distances are :
USA/Canada 15 miles
6dB net gain antenna configuration permitted (4W ERP)
Australia/NZ 12 km
unity gain antenna configuration (1W ERP)
Longer distances can be achieved if one antenna is mounted on top of a hill.
To achieve the maximum transmission distance, the antennas should be raised above
intermediate obstructions so the radio path is true “line of sight”. Because of the curvature of the
earth, the antennas will need to be elevated at least 15 feet (5 metres) above ground for paths
greater than 3 miles (5 km). The modules will operate reliably with some obstruction of the
radio path, although the reliable distance will be reduced. Obstructions which are close to either
antenna will have more of a blocking affect than obstructions in the middle of the radio path. For
example, a group of trees around the antenna is a larger obstruction than a group of trees further
away from the antenna. A WI-I/O 9-x module can be used with the WI-I/O K to display the radio
signal strength.
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.
Where it is not possible to achieve reliable communications between two WI-I/O 9-x modules,
then a third WI-I/O 9-x 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.
An antenna must be connected to each WI-I/O K module using the SMA connector at the top of
the enclosure.
It is important to weatherproof this connection by wrapping with
waterproofing tape
(for example 3M 23 tape).
The available antennas to be used with the WI-I/O 9-K units are:
WH900
Whip antenna for mounting directly onto the module - operation up to ½
mile (1 km)
CFD890EL
0 dBi Dipole antenna with 15’ of Cellfoil cable and SMA connector
SG900EL
5dBi Colinear omni-directional antenna with N-type connector
SG900-6
8dBi Colinear omni-directional antenna with N-type connector
