Telit Wireless Solutions NL865H2 Series, Руководство по конструкции аппаратуры

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NL865H2 Hardware Design Guide
1VV0301616 Rev. 7 Page 45 of 67 2020-04-20
6.1.2. PCB Design guidelines
When using the NL865H2-W1,
since there’s no antenna connector on the module, the
antenna must be connected to the NL865H2-W1 antenna pad by means of a transmission
line implemented on the PCB.
In the case the antenna is not directly connected at the antenna pad of the NL865H2-W1,
then a PCB line is needed in order to connect with it or with its connector.
This transmission line shall fulfil the following requirements:
Item Value
Characteristic Impedance 50 ohm
Max Attenuation 0,3 dB
Coupling Coupling with other signals shall be avoided
Ground Plane
Cold End (Ground Plane) of antenna shall be equipotential
to the NL865H2-W1 ground pins
The 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 NL865H2-W1 antenna line;
•
Keep the antenna line far away from the NL865H2-W1 power supply lines;
•
If you have EM noisy devices around the PCB hosting the NL865H2-W1, 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.