User's Manual

HE910 Hardware User Guide

1vv0300925 Rev.9 – 07-02-2012

6.2 GSM/WCDMA - PCB line Guidelines

Make sure that the impedance is 50ohm ;

Keep line on the PCB as short as possible, since the antenna line loss shall be less

than around 0,3 dB;

Line geometry should have uniform characteristics, constant cross section, avoid

meanders and abrupt curves;

Any kind of suitable geometry / structure (Microstrip, Stripline, Coplanar, Grounded

Coplanar Waveguide...) can be used for implementing the printed transmission line

afferent the antenna;

If a Ground plane is required in line geometry, that plane has to be continuous and

sufficiently extended, so the geometry can be as similar as possible to the related

canonical model;

Keep, if possible, at least one layer of the PCB used only for the Ground plane; If

possible, use this layer as reference Ground plane for the transmission line;

It is wise to surround (on both sides) the PCB transmission line with Ground, avoid

having other signal tracks facing directly the antenna line track.

Avoid crossing any un-shielded transmission line footprint with other signal tracks on

different layers;

The ground surrounding the antenna line on PCB has to be strictly connected to the

main Ground Plane by means of via holes (once per 2mm at least), placed close to the

ground edges facing line track;

Place EM noisy devices as far as possible from HE910 antenna line;

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

If EM noisy devices are present on 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.

If EM noisy devices are not present around the line, the use of geometries like

Microstrip or Grounded Coplanar Waveguide has to be preferred, since they typically

ensure less attenuation if compared to a Stripline having same length;