ST25R3911B- DISCO NFC Antenna Selection Advice

[Stephen2]

Hello

I’m currently designing an NFC product using the ST25R3911B reader IC and evaluating two standard NFC antennas from Leankon for read distance performance:

• LK1860701 (larger size)

• LK1860601 (smaller size)

Test Setup & Observations:

1. Matching Circuit Optimization:

   • Used datasheet parameters to optimize the matching network for both antennas.

   • Followed the recommended test methodology from the datasheet.

2. Test Tag:

   • Evaluated performance using ST’s Tag 5 as the reference target.

3. Results:

   • Both antennas achieved a similar read distance of ~80mm.

   • However, according to Leankon’s datasheet, the LK1860701 should achieve ~100mm.

Questions:

• Is this discrepancy normal? Could there be variations due to environmental factors or matching circuit tuning?

• Are there any key considerations I might have missed to further improve the read distance?

For reference, two antenna datasheets are attached,

LK1860101 NFC antenna  

LK1860701 NFC Antenna  

I’d appreciate any insights or suggestions. Thank you!

 

[Travis Palmer · Accepted solution]

Hello Stephen2,

Did you do your own reader board or do you use the ST25R3911B-DISCO as used in the datasheet of the tag.

There are two possible limitations for a NFC reader system:

1.) Tag communication is limited by the power transfer

--> optimize antenna size and output power to increase coupling and power transfer

2.) Tag communication is sensitivity limited

--> the backscatter is too small to be understood by the reader, there might be noise sources on the PCB/in the system which disturbs the receiver 

In addition the following post provide further details additional details:

https://community.st.com/t5/st25-nfc-rfid-tags-and-readers/design-questions-around-st25r3911b/m-p/370091#M7633

There are also two other posts linked, which might be of interest.

I propose that you try to reproduce the same setup as stated in the DS of the antenna. Maybe contacting the antenna manufacturer is a good idea to get further information how the ST25R3911B has been tuned.

please let us know, if you have additional questions.

BR Travis

[Stephen2]

Hello Travis

Thank you so much for your kind reply. 

I contacted Leankon and they provided their recommended matching values, then I can get the similar distance compared to their DS.

Thank you again.