Why is the NFC antenna measured at 1MHz and not 13.56MHz?

[JWbus.1]

The "AN5276" application note says we should measure the antenna at 1MHz.

I don't understand why we couldn't measure it directly at 13.56MHz.

[Ulysses HERNIOSUS]

Hi,

please see https://community.st.com/s/question/0D53W00001ixWvySAE/why-do-we-measure-the-nfc-anetnna-at-1mhz-not-1356mhz.

BR, Ulysses