External antenna for NUCLEO-NFC08A1?

[Jose_eflow]

Hi, 

Could you please confirm whether an external NFC antenna can be connected to the X-NUCLEO-NFC08A1 board? I see P200 and P202 in the schematic, but it is not clear to me whether these are intended for external antenna connection or only for optional/test points. If an external antenna can be used, could you explain how the on-board etched PCB antenna should be disconnected from the ST25R3916B antenna path, where the external antenna should be connected instead, and what antenna inductance or electrical parameters should be targeted before tuning the matching network?

Thanks!

Best regards, 

Jose
 

[Ulysses HERNIOSUS]

Hello Jose,

 

U.FL P200 and P202 are connected to AAT_A/B. They can be used to observe these signals coming from ST25R3916B.

If you want to connect and external antenna I recommend to attach to the pads (pink arrow) or the vias and cut the board around the dotted lines and break the antenna (4) off:

 

This way you have the matching at 3 at your disposal to change for your antenna. Please refer to the Antenna Design guide AN5276 for details on the target values and process.

 

BR, Ulysses