GSM/GPRS Module Series
M66 Hardware Design
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4
Antenna Interface
M66 has two antenna interfaces, GSM antenna and BT antenna. The Pin 26 is the Bluetooth antenna pad.
The Pin 35 is the GSM antenna pad. The RF interface of the two antenna pad has an impedance of 50Ω.
4.1. GSM Antenna Interface
There is a GSM antenna pad named RF_ANT for M66.
Table 22: Pin Definition of the RF_ANT
4.1.1. Reference Design
The external antenna must be matched properly to achieve best performance, so the matching circuit is
necessary, the reference design for RF is shown as below.
Module
RF_ANT
0R
NM
NM
Figure 40: Reference Design for GSM Antenna
Pin Name
Pin No.
Description
GND
34
Ground
RF_ANT
35
GSM antenna pad
GND
36
Ground
GND
37
Ground
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