User's Guide

LE920A4 HW User Guide Antenna(s)
Doc#: 1VV0301261 GPS/GNSS Antenna Requirements
Rev. 4.7.1 Page 65 of 124 2019-11-21
GPS/GNSS Antenna Requirements
The module supports an active antenna.
It is recommended to use antennas as follows:
 An external active antenna (17dB typ. Gain, GPS only)
 An external active antenna plus GNSS pre-filter (17dB typ. Gain)
NOTE:
The external GNSS pre-Filter is required for the GLONASS application.
The GNSS pre-filter must meet the following requirements:
 Source and load impedance = 50 Ohm
 Insertion loss (1575.42 – 1576.42 MHz) = 1.4 dB (Max)
 Insertion loss (1565.42 – 1585.42 MHz) = 2.0 dB (Max)

Insertion loss (1597.5515
–
1605.886
MHZ) = 2.0
dB (Max)
NOTE:
It is recommended to add a DC block to the customer’s GPS application to
prevent damage to the module due to undesired DC voltage.
NOTE:
It is recommended to add PI matching network near the GPS connector on
the application board in case that RF matching is needed.
7.5.1. Combined GPS/GNSS Antenna
The use of combined RF/GPS/GNSS antenna is NOT recommended. This solution can
generate an extremely poor GPS/GNSS reception. In addition, the combination of
antennas requires an additional diplexer, which adds significant power loss in the RF path.
7.5.2. Linear and Patch GPS/GNSS Antenna
Using this type of antenna introduces at least 3 dB of loss compared to a circularly
polarized (CP) antenna. Having a spherical gain response instead of a hemispherical gain
response can aggravate the multipath behaviour and create poor position accuracy.
7.5.3. Front End Design Considerations
Since there is no antenna connector on the module, the antenna must be connected to
the module through the PCB to the antenna pad.
If the antenna is not directly connected at the antenna pad of the module, a PCB line is
required. This line of transmission must meet the following requirements: