Antenna failure in ST25DV64KC

[Cheeeku]

Hi,

 

I have designed a board with a total antenna width of 10 mm and 7 turns, and a rectangular antenna.

But it doesn’t read by smartphone (NFC-enabled) or Readers.

 

Can you please help me with the problems?

 

[JL. Lebon]

Hello, 

Can you please give more information about the antenna characteristics? The important factor is the inductance of the antenna. For a ST25DV, it should be about 4.8uH.

You can also measure the tuning of the antenna+ST25DV tag. The tuning measurement is explained in this application note (chapter 4): How to design an antenna for dynamic NFC tags - Application note

It is also important that there is no ground plan under the antenna (it is not possible to check that on the layout shown here).

Best regards.