Guidance Needed for ST25R3920B NFC Antenna Design

[samueltshibangu]

Hello everyone,

I am currently working on the design of a board that incorporates the ST25R3920B NFC reader IC, aiming to achieve reliable tag detection at a maximum distance of 1 cm. Despite researching and reviewing multiple resources, I am still encountering challenges in the design process.

The specifications for my available antenna area are as follows:

• Antenna Size: 81 mm x 47 mm (rectangular PCB trace)
• Standard: ISO14443

If anyone has experience or insights on optimizing NFC antenna design for such a setup, I would greatly appreciate your guidance.

Thank you in advance for your support.

Best regards,
Samuel

[Travis Palmer]

Hello Samuel,

achieving 1cm read range with 81mm x 47mm should be straight forward.

Based on the available space you could place a ST25R3916B-STEVL like antenna in the free space and modify it to nicely fit.

You can use the antenna tool in the ST e-Design suite to estimate the inductance. It should be around 1uH.

https://eds.st.com/antenna/#/

Afterwards you should measure the antenna parameter of the final PCB (ideally with housing and metal parts, since they can change the antenna parameter. 

Afterwards simply follow the steps in the antenna design guide (AN5276).

Once you have the antenna parameters measured, we can support you calculating the matching.

br Travis