User's Manual

LE910 Hardware User Guide

1vv0301089 Rev.3 – 09-06-2014

 Ensure that the antenna line impedance is 50ohm.

 Keep the antenna line on the PCB as short as possible to reduce the loss.

 Antenna line must have uniform characteristics, constant cross section, avoid meanders and

abrupt curves.

 Keep one layer of the PCB used only for the Ground plane, if possible.

 Surround (on the sides, over and under) the antenna line on PCB with Ground, avoid having

other signal tracks facing directly the antenna line of track.

 The ground around the antenna line on PCB has to be strictly connected to the Ground Plane

by placing vias once per 2mm at least.

 Place EM noisy devices as far as possible from LE910 antenna line.

 Keep the antenna line far away from the LE910 power supply lines.

 Keep the antenna line far away from the LE910 GSM RF lines.

 If you have EM noisy devices around the PCB hosting the LE910, 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 do not have EM noisy devices around the PCB of LE910, use a strip-line on the

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

one.

RF Trace losses are difficult to estimate on a PCB without having the appropriate tables or RF

simulation software to estimate what the losses would be. A good rule of thumb would be to keep the

RF traces as short as possible, make sure they are 50 ohms impedance and don’t contain any sharp

bends.