User manual

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 the application.

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 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. 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.