User's Manual

LE910 Hardware User Guide

1vv0301089 Rev.7 – 25-10-2015

7.3 GPS/GLONASS Antenna Requirements

GPS/GLONASS ANTENNA REQUIREMENTS for LE910

Frequency range

1575.42 MHz ±2MHz (GPS)

1598.0625 – 1607.0625 MHz (GLONASS)

Average Gain over

direction

>-5dBi

Polarization

RHCP (recommended)

Linear (acceptable)

Avoid the use of LHCP antennas

Impedance

50 ohm

VSWR recommended

≤ 2:1 (recommended for best sensitivity performance)

7.3.1 GNSS 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 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,

LCD and so on, take care of the shielding of the antenna line by routing it in an inner layer 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 for the antenna line a

microstrip or G-CPW line on an outer layer of the PCB, since in this case the line attenuation is

lower in comparison to a buried one.