Telic LT910-WW - Antenna Type; Antenna Placement; The Antenna Cable; Possible Communications Disturbances

LT910-WW User Manual - Telic AG
Pg 29
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 the selected antenna meets the requirements specified in Section 4.2 (“Antenna
Connector”).
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. 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.
6.3.4 THE ANTENNA CABLE
Use 50Ω impedance low loss cable and high quality 50Ω impedance connectors (frequency range
up to 3GHz) 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.
6.3.5 POSSIBLE COMMUNICATIONS DISTURBANCES
Possible communication disturbances include the following:
 Noise can be caused by electronic devices and radio transmitters.
 Pathloss 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.