User manual

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5.3.2 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.
5.3.3 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 to use a cable antenna and place 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.
5.3.4 The antenna cable
Use 50Ω impedance low-loss cable and high-quality 50Ω impedance connectors (frequency
range up to 2GHz) to avoid RF losses. Ensure that the antenna cable is as short as possible.
The Voltage Standing-Wave Ratio (VSWR) may depend on the effectiveness of the antenna,
cable and connectors. In addition, if you use an adapter between the antenna cable and the
antenna connector, it is crucial that the antenna cable is a high-quality, low-loss cable.
Minimize the use of extension cables, connectors and adapters. Each additional cable,
connector or adapter causes a loss of signal power.
5.3.5 Possible communications disturbances
Possible communication disturbances include the following:
 Noise can be caused by electronic devices and radio transmitters.
 Path-loss occurs as the strength of the received signal steadily decreases in proportion to the
distance from the transmitter.
 Shadowing is a form of environmental attenuation of radio signals caused by hills, buildings, trees
or even vehicles. This can be a particular problem inside buildings, especially if the walls are thick
and reinforced.
 Multi-path fading is a sudden decrease or increase in the signal strength. This is the result of
interference caused when direct and reflected signals reach the antenna simultaneously. Surfaces
such as buildings, streets, vehicles, etc., can reflect signals.