NFC Antenna Inductance

[circuitsense]

When measuring the inductance and resistance of a rectangular antenna for PN53x using a VNA like miniVNA

at what frequency should the parameters be measured ? 

A) 1 MHz

B) 13.56 MHz.

AN11535 the document says measure it at 1 MHz.

AN1445 says measure it at 1 MHz.

Slide 21 of this presentation says - 

The antenna loop has to be connected to an impedance or network analyser at 13.56 MHz to measure the series equivalent components

(http://miniradiosolutions.com/wp-content/uploads/2015/09/NFC-Reader-Design-II-Antenna-design-conside...)

If I look at the NFC Antenna tuning video on NXP site the parameters measured are at 13.56 MHz.

(https://www.nxp.com/video/nfc-antenna-design-2-antenna-matching:ANTENNA-MATCHING-VIDEO)

I would like to know why the discrepancy ?? and what is the correct method.

[Kan_Li]

For the tuning we need L, R and C at 13.56MHz, so please follow the steps in the video of https://www.nxp.com/video/nfc-antenna-design-2-antenna-matching:ANTENNA-MATCHING-VIDEO, which is the simplest and correct way.

Hope that makes sense,

Have a great day,
Kan

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