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6.2.2
Securing the modem
Before securing the modem take into account the amount of additional space required for the mating
connectors and cables that will be used in the application.
Where access is restricted, it may be easier to connect all the cables to the modem prior to securing it in
the application.
Securely attach the CT63 NG Terminal modem to the host application using two 3mm diameter pan-head
screws.
6.3
Antenna
6.3.1
General
The antenna is the component in your system that maintains the radio link between the network and
the modem. Since the antenna transmits and receives electromagnetic energy, its efficient function will
depend on:
the type of antenna (for example, circular or directional);
the placement of the antenna;
Communication disturbances in the vicinity of the antenna.
The following sections address issues concerning antenna type, antenna placement, antenna cable, and
possible communication disturbances. In any event, you should contact your antenna manufacturer for
additional information concerning antenna type, cables, connectors, antenna placement, and the
surrounding area. You should also determine whether the antenna needs to be grounded or not. Your
antenna manufacturer might be able to design a special antenna suitable for the application.
6.3.2
Antenna type
Make sure that you choose the right type of antenna for the modem. Consider the following
requirements:
The antenna must be designed for the one of the frequency bands in use; please ask your network
provider for more information:
o
GSM 850/900 MHz
o
GSM 1800/1900 MHz;
The impedance of the antenna and antenna cable must be 50Ω;
The antenna output-power handling must be a minimum of 2W;
The VSWR value should be less than 3:1 to avoid any damage to the modem.
6.3.3
Antenna placement
The antenna should be placed away from electronic devices or other antennas. The recommended
minimum distance between adjacent antennas, operating in a similar radio frequency band, is at least
50cm. Therefore we recommend using a cable antenna and placing it away from the terminal. If signal
strength is weak, it is useful to face a directional antenna at the closest radio base station. This can
increase the strength of the signal received by the modem. The modem’s peak output power can reach
2W. RF field strength varies with antenna type and distance. At 10cm from the antenna the field
strength may be up to 70V/m and at 1m it will have reduced to 7V/m. In general, CE-marked products
for residential and commercial areas, and light industry can withstand a minimum of 3V/m.
