PN532 antenna range difference with JCOP3 and JCOP4 cards

[aman_cypherock]

Hi,

We are using a custom NFC module and flex PCB antenna with JCOP3 cards, it works with JCOP3 but not with the JCOP4 cards.

With JCOP3 the cards can be detected in <10mm range.
With JCOP4 the distance is <1mm (with a particular orientation).

Using a NanoVNA, I have managed to get minimum S11 and SWR parameters. But it doesn't seem to improve the range for either card.

Matching network values
L0=560nH,
C0=220pF,
C1=492pF,
C2=482pF

 
Below is the plot of the antenna setup without any cards in proximity.

Start freq:- 10MHz, Stop freq:- 20MHz

JCOP3 within 10mm of antenna

 

 

 

 

 JCOP4 within 10mm of antenna

 

A noticeable difference between JCOP3 and JCOP4 is the number of turns, JCOP3=5 turns, JCOP4=3 turns

My question:-
Is there any issue with current plots? and
What can be done to improve the range of the antenna with both cards?

Thanks in Advance

[Kan_Li]

Hi @aman_cypherock ，

Have you tried these two cards with NXP PN532 Demo board? Do they behave the same? Please kindly clarify.

Have a great day,
Kan

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[aman_cypherock]

Hi @Kan_Li,

I have tested with other readers(ACR122U and elechouse pn532 module) using PN532 and it works ok with both within range of 1cm.

[Kan_Li]

Hi @aman_cypherock ,

Thanks for the information! I think the root cause should be in antenna design, especially the tuning. Maybe you have to redo the tuning according to the following app notes.

https://www.nxp.com/docs/en/application-note/AN1445_An1444.zip

https://www.nxp.com/docs/en/application-note/AN11535.pdf

Please refer to https://www.nxp.com/products/rfid-nfc/nfc-hf/nfc-readers/nfc-integrated-solution:PN5321A3HN?fpsp=1&t... for more details.

Hope that helps,

Have a great day,
Kan

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