nRF52 NFC antenna and its equivalent inductance

[Lauri Jämsä]

Hi,

We decided to add NFC functionality to our nRF52 open source sensor beacon design, RuuviTag: http://ruuvi.com

I would like to ask your opinion about the antenna design, because Nordic hasn't published (correct me if wrong) any white papers or design guidelines about the NFC antennas.

Our NFC design files can be found from here: github.com/.../nfc-antenna

First I used STM's eDesignSuite to match the equivalent inductance to 2uH:

After that bended the antenna to fit our design:

Would it work? It sure needs tuning capacitors in place, but AFAIK, we need to make some measurements to find the correct values...

[Anders Strand]

Yes. There are some app notes out for other nfc devices, which explain the tuning process. For example this one from ST.