User's Manual

SIM800L Document
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from DC voltage. This is necessary because the antenna connector is DC coupled to ground via an inductor for
ESD protection.
The external antenna must be matched properly to achieve best performance, so the matching circuit is
necessary, the connection is recommended as following:
Figure1: GSM antenna matching circuit
R101，C101，C102 are the matching circuit, the value should be defined by the antenna design. normally R101
is 0Ω, C101 和 C102 are not SMD. The RF connector is used for conducted.
There are some suggestions to components placing and lying for GSM RF traces:
 The RF connector is used for conducted test, so keep it as close as pin RF_ANT;
 Antenna matching circuit should be closed to the antenna;
 Keep the RF traces as 50Ω；
 The RF traces should be kept far away from the high frequency signals and strong disturbing source.