GT864-3G Terminal Product Description
80269ST10071a Rev.0 - 14/09/0
9
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page 18 of 41
2.9 Antenna
2.9.1 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 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 application.
2.9.2 Antenna type
Make sure that you choose the right type of antenna for the modem. Consider the following
requirements:
Frequency range
UMTS/HSDPA 2100 MHz
GSM 850/900 MHz
GSM 1800/1900 MHz
Depending by frequency band(s) provided by
the network operator, the customer shall use
the most suitable antenna for that/those band(s)
Bandwidth
80 MHz in EGSM 900, 70 MHz in GSM 850,
170 MHz in DCS, 140 MHz PCS band, 250MHz in
WCDMA2100 band
Gain
< 3dBi
Impedance
50 ohm
Input power
> 33dBm (2W) peak power in GSM
> 24dBm Average power in WCDMA2100
VSWR absolute max.
<= 10:1
VSWR recommended
<= 2:1
2.9.3 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
