User's Manual

CL865-DUAL Hardware User Guide
1vv0301104 Rev.1 – 2014-03-07
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights
Reserved. Page 32 of 70
Mod. 0805 2011-07 Rev.2
instructions to remove or install the CL865 module. Antennas used for this OEM module
must not exceed 5dBi gain for mobile and fixed operating configurations.
7.1.1. CL865 Antenna – PCB line Guidelines
When using the Telit CL865 module, since there's no antenna connector on the module, the
antenna must be connected to the CL865 through the PCB with the antenna pad (pin 34).
In the case that the antenna is not directly developed on the same PCB, hence directly
connected at the antenna pad of the CL865, then a PCB line is needed in order to connect with
it or with its connector.
This transmission line shall fulfill the following requirements:
ANTENNA LINE ON PCB REQUIREMENTS
Impedance
50 ohm
Max Attenuation
0,3 dB
No coupling with other signals allowed
Cold End (Ground Plane) of antenna shall be equipotential to the
CL865 ground pins
This transmission line should be designed according to the following guidelines:
Ensure that the antenna line impedance is 50 ohm;
Keep the antenna line on the PCB as short as possible, since the antenna line loss shall be
less than 0,3 dB;
Antenna line must have uniform characteristics, constant cross section; avoid meanders and
abrupt curves;
Keep, if possible, one layer of the PCB used only for the Ground plane;
Surround (on the sides, over and under) the antenna line on PCB with Ground, avoid having
other signal tracks facing directly the antenna line track;
The ground around the antenna line on PCB has to be strictly connected to the Ground Plane
by placing vias every 2mm at least;
Place EM noisy devices as far as possible from CL865 antenna line;
Keep the antenna line far away from the CL865 power supply lines;
If you have EM noisy devices around the PCB hosting the CL865, such as fast switching ICs,
take care of the shielding of the antenna line by burying it inside the layers of PCB and
surround it with Ground planes, or shield it with a metal frame cover.
If you don't have EM noisy devices around the PCB of CL865, by using a micro strip on the
superficial copper layer for the antenna line, the line attenuation will be lower than a buried
one;