Antenna Type; Antenna Placement; The Antenna Cable - Wavecom GR64 GSM/GPRS Integrator's Manual

7.5.2

Antenna Type

Users should ensure that they choose the right type of antenna for the Wireless CPU.
The antenna must be designed for the frequency bands deployed in the regions that
the Wireless CPU is being used.
example E-GSM900/GSM1800 in Europe; GSM850/GSM1900 in North America). For
applications which are mobile, users should consider whether three or all four GSM
bands could be encountered.
Other factors in choosing antenna are equally important:
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7.5.3

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 50 cm.
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 Wireless
CPU.
The Wireless CPU's peak output power can reach 2 W. RF field strength varies with
antenna type and distance. At 10 cm from the antenna the field strength may be up
to 70 V/m and at 1m it will have reduced to 7 V/m.
In general, CE-marked products for residential and commercial areas, and light
industry can withstand a minimum of 3 V/m.
7.5.4

The Antenna Cable

Use 50 ohm impedance low-loss cable and high-quality 50 ohm impedance
connectors (frequency range up to at least 2 GHz) to avoid RF losses. Ensure that the
antenna cable is as short as possible.
The effectiveness of the antenna, cable and connectors is determined by their quality.
All connectors, adaptors and cables should be of the highest quality, lowest loss,
lowest VSWR rating that is affordable to the user.
GR64 Integrators Manual
Page: 88/104
Impedance of the antenna and antenna cable must be 50 ohms at all
frequencies being used.
Antenna output-power handling capability must be a minimum of 2 W.
Antenna VSWR value should be less than 3:1 to avoid damage to the radio
device.
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For fixed locations this may be dual bands (for