User's Manual

UE866 HARDWARE USER GUIDE 1vv0301157 Rev.7 • 2015-04-17 48 of 68

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 UE866 antenna line;

 Keep the antenna line far away from the UE866 power supply lines;

 If you have EM noisy devices around the PCB hosting the UE866, 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 UE866, by using a micro strip on the

superficial copper layer for the antenna line, the line attenuation will be lower than a buried

one;

The following image is showing the suggested layout for the Antenna pad connection: