User's Manual

LE910 Hardware User Guide

1vv0301089 Rev.3 – 09-06-2014

 Make sure that the transmission line’s characteristic 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 LE910 antenna line;

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

 If EM noisy devices are present on 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 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;