MeiG Smart product technical information
SLM758
Hardware Design Guide
Page 59
4.18 Antenna Interface
The module provides four antenna interfaces: MAIN antenna, DRX antenna, GPS antenna
and WiFi/BT antenna. In order to ensure that the user's products have good wireless
performance, the antenna selected by the user should meet the requirement that the input
impedance is 50 ohms in the working frequency band and the VSWR is less than 2.
4.18.1 Main Antenna
The module provides the MAIN antenna interface pin Pin1 RF_MAIN. The antenna on the
user's main board should be connected to the antenna pin of the module using a 50-ohm
characteristic microstrip line or strip line.
In order to facilitate antenna debugging and certification testing, an RF connector and
antenna matching network should be added. The recommended circuit diagram is as follows:
Figure 4.34: MAIN Antenna Interface Connection Circuit
In the figure, R101, C101, and C102 are antenna matching devices, and the specific
component values can be determined after the antenna factory debugs the antenna. Among
them, R101 defaults to 0R, C101 and C102 do not paste by default.
If there are fewer components between the antenna and the module output, or if the RF test
head is not needed in the design, the antenna matching circuit can be simplified as shown
below:
Figure 4.35: MAIN Antenna Interface Simplified Connection Circuit
In the above figure, R101 defaults to 0R, and C101 and C102 do not paste by default.
