external antenna branching issue

[idrawone]

I want to keep both chip antenna and external antenna options on our board, what is best way to handle this for nRF24LE1 4×4mm QFN24 chip-set? Can I branch the Radio by having a 0ohm resistor soldering in different way? Any reference design and layout available?

[Andreas]

Hi,

 

The simplicity of the answer depends if you want to transmit and receive with both antennas at the same time or not, The easiest is not, to only use one antenna at a time. In that case it is fine to use a 0 Ohm resistor or >10pF cap soldered towards the branch and antenna of you choice(only 1 at a time!). Just have them share the solder pad on the nRF24-side, placed on the transmission line itself. Alternatively, you can use a switch connector, similar to the one on the nRF5x-DKs.

From what I know we do not have any reference designs with this, but if you replicate the nRF24LE1 reference design (without coaxial connector) and place one as you describe, you should be well on your way. Feel free to submit the design to us early in the layout process for a review and feedback on your implementation.

 

If you want the antennas to operate at the same time I would recommend to use a SMD power splitter or similar. This is a device that splits the signal from the nRF into two signals of equal strength towards each antenna, and the other way directing (most of)the signal from each antenna towards the nRF. This is only valid when both the antennas are in place.

 

Best regards,

Andreas