Installation of the modem
INSYS GPRS mini
8.6
Antenna
8.6.1
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 re-
ceives 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 place-
ment, and the surrounding area. You should also determine whether the an-
tenna needs to be grounded or not. Your local antenna manufacturer might
be able to design a special antenna suitable for the application.
8.6.2
Antenna type
Make sure that you choose the right type of antenna for the modem. Con-
sider 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 50
Ω
;
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.
8.6.3
Antenna placement
The antenna should be placed away from electronic devices or other anten-
nas. The recommended minimum distance between adjacent antennas, op-
erating in a similar radio frequency band, is at least 50cm. Therefore we rec-
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