For many Bluetooth applications that require high performance and long distance or small size, developers would like to utilize Bluetooth modules that supports external antennas in their PCBA. Because usually the most efficient way to make the transmission range of a Bluetooth module longer and make the PCBA's size smaller, would be removing the onboard antenna part and use external antenna instead.
But what would be the best way to set up the external antenna?
Taking a two-layer PCBA as an example:
1. Ensure that the components on the board are well organized.
2. Ensure that there is a large area of ground copper and a sufficient number of through holes.
3. The RF microstrip line needs to do 50-ohm impedance, the reference layer is the second layer.
4. Reserve the π-type matching circuit, and make it close to the RF seat. Through the debugging of the matching circuit, ensure that the antenna is in the best state.
5. Ensure that the RF microstrip line is surrounded by the ground wire (shield).
6. Do not put data line, clock line, etc. on the bottom of the module, and keep the bottom as a large and complete ground plane.
7. Combined with the layout diagram of the second layer, it can be seen that the RF microstrip line is three-dimensionally surrounded by the ground (shield).
In conclusion, make sure the external antenna is placed in the right position, and make sure that the antenna is unaffected from the other lines on the board.
Should you have any questions during external antenna setting, don’t hesitate to contact Feasycom now!