separate Antenna PCB for St25R3916B reader

[Dilip]

Hi ST team, 

We are going to use the ST25R3916B chip in our project to design NFC reader. Due to mechanical design constraints, I have to place the antenna in separate PCBA near NFC tag. I would like to know how should i connect my RF output from reader board to antenna. Distance from reader PCBA to antenna required around 30-40 cm. Can you pls suggest will this solution work and what type of cable is required. Also what specific design considerations i have to take care?

[Ulysses HERNIOSUS]

Hi Dilip,

please see AN5592 with its chapter 2.3 "Single ended antenna with cable"

BR, Ulysses

[Dilip]

Thanks Ulysses,

In our project, we already have tag (NXP NTAG213) in the products, Now we would like to read these tags from ST25R3916B reader, so I have few questions:

1.  Is ST25R3916B correct selection? do you suggest anything else?

2.  Antenna size in tag is 10mmX17mm, what antenna size i should design for ST25R3916B reader to have more than 10 cm read range with this tag?

3. What tags should I use from ST make to get the read range of about 30cm with ST25R3916B reader?

Thanks in advance

Dilip M

[Ulysses HERNIOSUS]

Hi Dilip,

ad 1) Any of our reader chips can read T2T, so 16B is good.

ad 2) I am more on the software side but not sure it is feasible to reach the desired range with such a small tag antenna. I suggest you do some experiments with STEVAL-25R316B which has already a not so small antenna.

ad3)  Typically NFCV tags can achieve quite a range but there you need to also anticipate big antennas on reader side. (Similar to what is done with Ski passes in Ski resorts).

Regards, Ulysses 

[Dilip]

Hi Ulysses, 

Thanks for your suggestions and solutions.

I have already ordered the STEVAL-25R3916B board for testing with my existing tag , also ordered ordered a bag of few different tags-  ST25-TAG-BAG-UT1 to test with eval board.

Can you Pls provide me parts numbers of NFCV tags and approximate what size of antenna is required at reader side to get the read range of around 30cm?

Thanks & Regards

Dilip M

[Ulysses HERNIOSUS · Accepted solution]

Hi Dilip,

I cannot offer here detailed advice. I am checking if some other colleagues could.

General recommendation is: ID1 sized NFC-V tags plus a reader antenna sized such that its diameter corresponds to the required range - in your case 30cm. With such a setup it should be possible to reach the 30cm range.

I think you will need to perform some experiments, to optimize, but that could be a starting point.

BR, Ulysses