what is inductance(uH) of the X-NUCLEO-NFC04A1

[sliu.5]

There is a Spiral antenna in the X-NUCLEO-NFC04A1. The link is https://www.st.com/content/st_com/en/products/ecosystems/stm32-open-development-environment/stm32-nucleo-expansion-boards/stm32-ode-connect-hw/x-nucleo-nfc04a1.html

By the document AN2972(How to design an antenna for dynamic NFC tags),In section 3.2 Inductance of a spiral antenna

,there is a calculation formula about a spiral antenna.As follow,

those parameters are:

d = 40mm

N = 8

c = 35um

The result of inductance is   1.7870e-05H.

It is not 4.5uH,Why? because capacitance of st25dv04 is 28.5 pf.

For the ST25dv series,what is the best inductance of antenna? 4.5uH or not?

BR,

Liu

[John_zhang]

Hi HC,

My friend Liu has no time to reply. Select this package is that it has very small package and 64kb. SO8N and TSSOP package is big . UFDFPN8 is only 4kb version.Would you tell me your email? We have some questions.

Thank you very much!

BR,

John