X-NUCLEO-NFC06A1 - External antenna

[pagano.paganino]

Hi all,

is it possible to connect an external antenna to the X-NUCLEO-NFC06A1, if possible, where?

Thanks,

D.

[Rene Lenerve]

Hi @pagano.paganino​ ,

The NFC06 has a breakable antenna, and there are three pads available to connect an external antenna. But at this point you must know what you are doing because the matching circuitry will not be adapted to your new antenna so you will also have to match it.

Here are some links to useful documentation and tool:

• ST25R3916 automatic antenna tuning : https://www.st.com/content/ccc/resource/technical/document/application_note/group1/b6/80/cf/69/2e/3a/4e/7a/DM00613968/files/DM00613968.pdf/jcr:content/translations/en.DM00613968.pdf
• Antenna design for ST25R3916 : https://www.st.com/content/ccc/resource/technical/document/application_note/group1/8c/7f/3c/81/1c/19/4c/e3/DM00591454/files/DM00591454.pdf/jcr:content/translations/en.DM00591454.pdf
• Matching antenna tool : https://www.st.com/content/st_com/en/products/embedded-software/st25-nfc-rfid-software/stsw-st25r004.html

Best Regards.

[JGreve]

When you break off the antenna, the three pads stay on the antenna rendering the NFC06A1 board useless. Unless there is another way to attach an antenna?

 

@Rene Lenerve​ can you tell me where in the documentation that you have linked, you find the information you need to match and connect an external antenna? Unfortunately, I can't seem to find it anywhere.

Br. Jørgen

[JGreve]

@Rene Lenerve​ ?

[Rene Lenerve]

Hi @Jørgen Greve​,

If you look at the schematics https://www.st.com/resource/en/user_manual/um2615-getting-started-with-the-nfc-card-reader-expansion-board-based-on-st25r3916-for-stm32-and-stm8-nucleos-stmicroelectronics.pdf, you can have access to the two lines of the antenna with R300 (ANT2) and R302 (ANT1). The third one is connected to the ground with R304.

Kind Regards.

[JGreve]

Thank you, but I can still not find information about how to match the external antenna. I need information about the matching network to be able to design an antenna that matches. I know this is kind of backwards since you normally design the antenna and then the matching circuit to match the antenna to the ST25R3916. But since the matching circuit is already in place, I can't do that.

Br. Jørgen

[Rene Lenerve]

Hi @Jørgen Greve​,

NFC06 nucleo expansion board is build around an ST25R3916 and you can find resources on the web page here https://www.st.com/en/nfc/st25r3916.html#documentation or here https://www.st.com/en/nfc/st25r3916.html#tools-software.

• Antenna Matching Tool for ST25R NFC/HF reader family
• AN5276 Antenna design for ST25R3916/16B, ST25R3917/17B, ST25R3918, and ST25R3920/20B devices
• AN5592 ST25R single ended antenna matching

Hope this can help you.

Kind Regards.

[JGreve]

I know, that is why I mentioned that I am working on the NFC06A1 expansion board containing the ST25R3916 NFC IC.

One would think that ST had included such information in the documentation you have linked to both in the top of this thread and now here. But it still remains to be found. I have tried for at least a week now.

Could you please point to where in the documentation I can find the values I need to design an antenna for the NFC06A1 expansion boards matching circuit?

Br. Jørgen

[Arimsa Has]

Hi @Jørgen Greve​ ,

On this picture you can see one example : the NFC06A1 board connected with 66x66mm antenna.

First step is to measure antenna parameters. In this app note (Antenna matching for ST25R3911B/ST25R391x devices - Application note) on the page 16 you will find all information how to measure antenna parameters of antenna. So values that you need for matching circuit depend on your designed antenna.

After you have antenna parameter, you can use the "STMicroelectronics ST25R Antenna Matching Tool" to determine the matching components. (See page 27, 28,29 Antenna matching for ST25R3911B/ST25R391x devices - Application note ).

I hope this can help you.

Best regards

[JGreve]

Hi @Arimsa Has​ 

I am aware that you design an antenna and afterwards match it to the RF IC with a matching network, but that is clearly not the intended way to do it on the NFC06A1 board since there is no solder pads on the ST25R3916 side of the matching network.

Both your picture and @Rene Lenerve​ suggest that the new antenna is soldered directly to the output terminals of the matching network. And since ST has not provided the necessary information in the documentation for me to do da that, I am a bit in a pickle.

What is the intended way to attach a new antenna to the NFC06A1 board and why is it not properly described in the NFC06A1 documentation?

Br. Jørgen

[Arimsa Has]

Hi @Jørgen Greve​ ,

There is no possibility to add additional components for the new antenna, as there is no spare/free pad.

You will need to replace the existing matching components with the ones to make it suitable for the new antenna.

Best regards