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39
Hardware Development Guide
ME3616
3.
A
NTENNA
I
NTERFACE
ME3616 has one main antenna interface; the impedance of the antenna interface is required to reach 50
ohms.
3.1.
PIN
D
EFINITION
The main antenna pin definition is shown below.
Table 3-1 Pin Definition of Antenna
Pin Name
Pin NO.
I/O
Description
Comment
MAIN_ANT
27
IO
main antenna
50±5
Ω
impedance
3.2.
R
EFERENCE
D
ESIGN
The antenna is a sensitive device and its performance is greatly affected by external environments. The
radiation performance of the antenna is affected by the module dimensions, antenna position, occupied space
size of the antenna, and the grounding of surrounding components of the antenna. Besides, the fixed assembly of
the antenna, the wiring of RF cables on the antenna, and the fixed position of the antenna all affect the radiation
performance of the antenna too.
The reference design of main antenna is shown as below. It should reserve a double-L-type matching circuit
for better RF performance, and place these components as close as possible to the module. The capacitors are not
mounted by default.
Figure 3-1 Reference Circuit of Antenna Interface
3.3.
R
EFERENCE
PCB
L
AYOUT OF
A
NTENNA
Please refer to the following criterion in the process of antenna line PCB layout design:
Make sure that the transmission line’s characteristic impedance is 50ohm;
Keep line on the PCB as short as possible, since the antenna line loss shall be less than 0.3 dB;
Line geometry should have uniform characteristics, constant cross section, avoid meanders and abrupt curves;
It is wise to surround the PCB transmission line with ground, avoid having other signal tracks facing directly the antenna line
track.
Keep at least one layer of the PCB used only for the ground plane; and use this layer as reference ground plane for the