Telit Wireless Solutions HE910 - GSM;WCDMA PCB Transmission Line Guidelines

HE910 Hardware User Guide
1VV0300925 Rev. 32 Page 53 of 111 2019-11-25
This transmission line shall fulfil the following requirements:
ANTENNA LINE ON PCB REQUIREMENTS
Characteristic Impedance
50 ohm
Max Attenuation
0,3 dB
Coupling with other signals shall be avoided
Cold End (Ground Plane) of antenna shall be equipotential to the HE910 ground
pins
Furthermore if the device is developed for the US market and/or Canada market, it shall
comply with the FCC and/or IC approval requirements:
This device is to be used only for mobile and fixed application. In order to re-use the Telit
FCC/IC approvals the antenna(s) used for this transmitter must be installed to provide a
separation distance of at least 20 cm from all persons and must not be co-located or
operating in conjunction with any other antenna or transmitter. If antenna is installed with
a separation distance of less than 20 cm from all persons or is co-located or operating in
conjunction with any other antenna or transmitter then additional FCC/IC testing may be
required. End-Users must be provided with transmitter operation conditions for satisfying
RF exposure compliance.
Antennas used for this OEM module must not exceed the gains for mobile and fixed
operating configurations as described in “FCC/IC Regulatory notices” chapter.
GSM/WCDMA - PCB line Guidelines
• 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;