User's Manual

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L816-AM Hardware User Manual Page
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4.4 RF PCB Design
4.4.1 Trace Routing Principle
The L816-AM module supports dual antennas, which meets the requirements for LTE of 3GPP. The
MAIN_ANT is used to transmit and receive RF signals, while the DIV_ANT is used to receive RF signals.
Using diversity antenna to improve the receiving sensitivity of RF antenna and double the download rate.
Since L816-AM is an LTE module, dual antennas should be applied to meet the performance
requirements.
The L816-AM module does not provide RF connector itself, so routing RF traces are required for the
connection with RF connectors or antenna feed points on the application mainboard. It is recommended
to use the microstrip line for RF trace, with the insertion loss controlled within 0.2dB and impedance
controlled at 50Ω.
It is recommended to reserve a π circuit (the parallel inductors should connect to the RF trace) between
the L816-AM module and the antenna connectors (or the feed points). The parallel devices are directly
across the RF lines and no branch is allowed.
Figure 4-1 L816-AM Antenna π Circuit
4.4.2 RF Impedance Design
The RF traces impedance of the antenna interface shall be controlled at 50Ω.