User manual

105G Wireless Gateway User Manual
Elpro_man_105g_1.18.doc Page 28
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.
Where it is not possible to achieve reliable communications between two modules, then another
105U or 105G modules may be used to receive the message and re-transmit it. This module is
referred to as a repeater.
An antenna should be connected to the module via 50 ohm coaxial cable (e.g. RG58, RG213 or
Cellfoil) terminated with a male 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 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 gains and losses of typical antennas are
Antenna Gain (dB)
Dipole with integral 3m cable 0
Dipole without cable 2
5dBi Collinear (3dBd) 5
8dBi Collinear (6dBd) 8
3 element Yagi 5
6 element Yagi 10
Cable type Loss (dB per 10 m)
400-500MHz 869MHz
RG58 -3 -5
RG213 -1.5 -2.5
Cellfoil -1.5 -3
The net gain of the antenna/cable configuration is determined by adding the antenna gain and the
cable loss. For example, a 3 element Yagi with 15 meters of RG58 has a net gain of 0.5dB (5dB
– 4.5dB) @450MHz.
For information on antennas and cables for the 105U licensed products, please contact to ELPRO
Technologies or an authorized distributor.
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 vulcanizing tape such as “3M 23 tape”, and finally
with another layer of PVC UV Stabilized insulating tape. The first layer of tape allows the joint
to be easily inspected when trouble shooting as the vulcanizing seal can be easily removed.