NFC ST25DV with Vicinity card

[Jignesh]

Hi,

We are using ST25DV04K dynamic tag with internal taoglas antenna FXR.07.A with ISO15693 protocol in our product. We are hardly getting 4cm distance with CR95HF reader. We would like to increase distance upto ~9cm. With same reader we can get 7-8cm on TI 15693 passive tag.

Can any one guide me how can i increase distance from ST25DV side?

As I have also read about vicinity card can give upto 1meter. How can i implement vicinity card in ST25DV.

Thanks & Regards,

Jignesh Patel

[JL. Lebon · Accepted solution]

​Hello,

The reading distance is very dependent on antenna size and tunning, and RF field power delivered by the reader.

With a ST25DV04K soldered on a class 1 antenna (credit card size) correctly  tunned, you can expect ~8cm with a CR95HF.

If you want to reach higher distances, you need a more powerfull reader. With a St25R3911B, you can expect ~14cm in same conditions.

To reach distances like a meter, a very powerfull reader with a big antenna is requiered. Such readers are industiral readers (i.e. Feig LR1002), and can deliver several watts of power in very large antennas.

So if ou want more reading range with CR95HF + ST25DV, I recommand you to increase antenna size and to check it's tunning.

You can find all informations about how to design and tune an antenna for vincinity card in the application note AN2972 https://www.st.com/resource/en/application_note/cd00232630-how-to-design-an-antenna-for-dynamic-nfc-tags-stmicroelectronics.pdf

Best regards.

[Jignesh]

Thanks JL. Lebon For reply,

I will check with larger antenna size and application note.

Does ST25TV series tag will help with CR95HF to increase detection distance ?

Best regards,

Jignesh Patel

[JP Miller]

​Dear Jignesh,

With respect to your question on whether the ST25TV series tag will help with CR95HF to increase detection distance (up to 1m I guess), the results would be similar between the ST25TV series and the ST25DV series.

Choosing between ST25TV or ST25DV is rather to be determined based on the use case you are interested in. Even though both are NFC Forum Tag 5 Types tags, the features set is very different from one another, starting from the fact ST25DV is a dynamic tag, while ST25TV is not.

Datasheet are available on https://www.st.com/en/nfc/st25-nfc-rfid-tags-readers.html for more information

Regards