User's Manual

HE910 Hardware User Guide

1vv0300925 Rev.9 – 07-02-2012

When using the Telit HE910, since there is no antenna connector on the module, the

antenna must be connected to the HE910 through the PCB with the antenna pad.

In the case that the antenna is not directly developed on the same PCB, hence directly

connected at the antenna pad of the HE910, then a PCB line is needed in order to

connect with it or with its connector.

This line of transmission must fulfill the following requirements:

Antenna Line on PCB Requirements

Impedance

50 ohm

No coupling with other signals allowed

Cold End (Ground Plane) of antenna must be equipotential to

the HE910 ground pins

Furthermore if the device is developed for the US and/or Canada market, it must comply with

the FCC and/or IC approval requirements:

This device is to be used only for mobile and fixed application.

6.5.4 GPS Antenna - PCB Line Guidelines

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 HE910 antenna line.

Keep the antenna line far away from the HE910 power supply lines.

Keep the antenna line far away from the HE910 GSM RF lines.

If you have EM noisy devices around the PCB hosting the HE910, 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.