0
\$\begingroup\$

I'm looking for help with my NFC (13.56MHz) antenna design. I am using a NXP-NT3H2111 NFC IC and so far I have read through the application note and other research papers available online to try design an NFC antenna. I'm not sure about how to verify the functionality of my antenna before fabrication (i.e. in HFSS ) generally, for an antenna we measure parameters such as S11; Rad-pattern but I have no clue regarding the parameter constraints for a NFC antenna. These are my design parameters, the main reason for choosing the following parameters is because this dimension falls under class 6 antenna category in NFC.

This image is my NFC antenna design, I have made use of the tool provided by NXP to calculate the dimensions and other values but I am not sure about verifying the functionality in HFSS. I tried measuring the S11 but there was no dip in at the desired frequency & even at the self-resonance frequency of the antenna there was no changes in the S11 plot.

I am really confused about how to proceed further, I dont think there are any geometrical errors in my design but I do have a strong feeling that I may have made some mistake when it comes to simulating the antenna ( giving wrong excitation and such things ) I would be grateful if anyone of you can point me in the right direction.

\$\endgroup\$

1 Answer 1

Reset to default
0
\$\begingroup\$

No need to have such a wide track and track separation/gap. Rather have 0.2 mm for both. Route the track at the outer edges, leaving an empty area in the middle - the geometry will allow better read distance. I know a similar design with 8 turns worked well, 6 will probably be ok too.

The coil itself should show a dip at self-resonance. Below self-resonance it should look like an inductor.

\$\endgroup\$
7
  • \$\begingroup\$ okay thank you @Ralph, can you tell me if I can leave them as perfect H ? or should I change that as well \$\endgroup\$
    – Ethan25
    Commented Dec 16, 2023 at 3:46
  • \$\begingroup\$ I made all the changes, as suggested by @Ralph but still not able to get anything. I have been sitting on this one for weeks now, would really appreciate any assistance you can give me. \$\endgroup\$
    – Ethan25
    Commented Dec 16, 2023 at 8:05
  • \$\begingroup\$ @Ethan25 Are you not seeing the self-resonance? It should be somewhere well beyond 13.56 MHz. Or are you not getting any energy harvested while near to a reader? Please post all the details of the setup. The IC will complete the receiver circuit, so the receiving coil should just be an inductor. You should build the circuit and see if you get any voltage in Vout of the IC while near to an active reader. \$\endgroup\$
    – Ralph
    Commented Dec 16, 2023 at 10:01
  • \$\begingroup\$ the S11 curve becomes a straight line beyond a point. Yes I understand the part about the receiving coil just being an inductor. I did build the circuit with the RLC components in HFSS and the S11 plot was no different from the previous one. @Ralph. \$\endgroup\$
    – Ethan25
    Commented Dec 16, 2023 at 10:47
  • \$\begingroup\$ I did try different excitation points ; placed the matching capacitor at different points but nothing seem to have any effect. I also plotted the H-field and there was a strong H field presence. \$\endgroup\$
    – Ethan25
    Commented Dec 16, 2023 at 10:50

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.