User's Manual

LE940B6 Hardware User Guide

1VV0301331 Rev. 1.8 - 2017-03-15

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7.3. GSM/WCDMA/TD-SCDMA/LTE Antenna – Installation Guidelines

• Install the antenna in a location with access to the network radio signal.

• The antenna must be installed such that it provides 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.

• The antenna must not be installed inside metal cases.

• The antenna must be installed according to the antenna manufacturer’s instructions.

7.4. Secondary Antenna Requirements

This product includes an input for a second Rx antenna to improve radio sensitivity. The function

is called Antenna Diversity.

Since there is no antenna connector on the LE940B6 module, the antenna must be connected to

the LE940B6 antenna pad by means of a transmission line implemented on the PCB.

If the antenna is not directly connected at the antenna pad of the LE940B6 (AU9), a PCB line is

required to connect to it or to its connector.

The second Rx antenna must not be located in close vicinity of the main antenna. To improve

diversity gain and isolation and to reduce mutual interaction, the two antennas should be located

at the maximum reciprocal distance possible, taking into consideration the available space within

the application.

NOTE:

If Rx Diversity is not used/connected, disable the Diversity functionality using the AT+XRXDIV

command (refer to Ref 1: LE940B6 AT Command Reference Guide) and connect the Diversity pad

AU9 to a 50 Ohm termination.

7.5. PCB Guidelines in case of FCC certification

In the case FCC certification is required for an application using LE940B6-NA, according to FCC

KDB 996369 for modular approval requirements, the transmission line has to be similar to that

implemented on module’s interface board and described in the following chapter.

7.5.1. Transmission line design

During the design of the interface board, the placement of components has been chosen

properly, in order to keep the line length as short as possible, thus leading to lowest power losses

possible. A Grounded Coplanar Waveguide (G-CPW) line has been chosen, since this kind of

transmission line ensures good impedance control and can be implemented in an outer PCB layer

as needed in this case. A SMA female connector has been used to feed the line.