User Manual

Confidential
USERS MANUAL
41(42)
Document number Revision
4/198 17-LXE 108 566 Uen PA7
5.4 Antenna
5.4.1 Antenna Type
When choosing an antenna for your application you must consider the following
requirements:
•
The antenna must be designed for the AMPS/CDMA 800 and CDMA 1900 MHz
frequency band (dual band) for the CM-52.
•
The impedance of the antenna and antenna cable must be 50

.
•
The VSWR value should be less than 2:1.
5.4.2 Antenna Placement
Always follow the instructions supplied by the antenna manufacturer.
You should place the antenna 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 centimeters.
If the module is used in the Class I AMPS mode, a separation distance of at least 23
centimeters must be maintained between the radiating antenna and the user or nearby
persons. In this mode of operation, the combined connection cable path loss and
antenna gain must also be no greater than 1 dBi.
5.5 Possible Communication Disturbances
Noise can be caused by electronic devices and radio transmitters.
Free Space Path-loss occurs as the strength of the received signal steadily decreases
with the distance from the transmitter.
Shadowing is a form of environmental attenuation of radio signals that is caused by hills,
buildings, trees or even vehicles. Inside buildings this can cause problems, 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 mobile phone
simultaneously. Flat surfaces such as buildings, streets, vehicles, etc, can reflect
signals.