10. INSTALLATION OF THE CONTROL TERMINAL
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LZ T 123 7 605 P1C
10.3 Antenna
10.3.1 General
The antenna is the component in your system that maintains the radio link
between the network and the Control Terminal. 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 in which the antenna
operates.
In the sections below, issues concerning antenna type, antenna placement,
antenna cable, and possible communication disturbances are addressed.
In any event, you should contact your local 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 local antenna
manufacturer might be able to design a special antenna suitable for your
the application.
10.3.2 Antenna Type
Make sure that you choose the right type of antenna for the Control
Terminal. Consider the following requirements:
• the antenna must be designed for the dual frequency bands in use:
EGSM 900/GSM 1800 for GT47, GSM 850/ GSM 1900 for GT48
• the impedance of the antenna and antenna cable must be 50
Ω
• the antenna output-power handling must be a minimum of 2W;
• the VSWR value should be less than 3:1 to avoid damage to the Control
Terminal.
10.3.3 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.
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 Control Terminal.
The Control Terminal’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.