905U-L Wireless I/O Installation Manual
905U-L Wireless I/O
Page 16 of 40
Version 1.9
Installing and earthing antennas
You must connect an antenna to each 905 module using the SMA connector at the top of
the enclosure.
ELPRO recommends carefully taping the connections between the antenna and coaxial
cable to prevent moisture ingress. Moisture ingress in the coaxial cable is a common
cause of radio system problem as it greatly increases the radio losses.
ELPRO recommends taping the connection with three layers of tape:
Layer
Tape
1
PVC tape.
2
Vulcanising tape (e.g. 3M 23 tape).
3
Additional layer of PVC UV-stabilized insulating tape.
The first tape layer lets you easily inspect the joint if required as you can easily remove
the vulcanising seal.
Note
You must effectively earth all masts for mast-mounted antennas to avoid lightning surges.
We also recommend using a coaxial surge diverter for antennas mounted outside industrial
plant environments.
If the antenna is not already shielded from lightning strike by an adjacent earthed
structure, you can provide shielding by installing a lightning rod above the antenna.
You should connect the antenna to the module using 50 ohm coaxial cable (e.g. RG58 or
RG213) terminated with a male coaxial connector, The higher the antenna is mounted, the
greater the transmission range; however as the length of coaxial cable increases so do
cable losses. For use on unlicensed frequency channels, there are several types of
antenna suitable for use.
If you mount antennas on elevated masts, you should effectively earth the masts to avoid
lightening surges. The 905U-L radios are fitted with surge protection.
Note
For high lightening risk areas, ELPRO recommends additional surge suppression devices.
If the antenna is not already shielded from lightening strike by an adjacent earthed
structure, you can install a lightening rod to provide shielding.
