What product should I choose to use a custom antenna

[Mc3]

Hello everyone,

I am working on a project in which I will use NFC tag. I though to use ST25R shield for nucleo board but I need a product on which I can use my own antenna and my own matching circuit.

Do you have advice on which product to choose ?

Thanks in advance

Mathieu

[Brian TIDAL]

Hi Mathieu

do you plan to redesign a PCB with your own matching and own antenna or do you plan to modify an existing X-NUCLEO-NFC0*A1 board?

X-NUCLEO-NFC06A1 (ST25R3916 High performance NFC universal device and EMVCo reader) and X-NUCLEO-NFC05A1 (High performance HF reader / NFC initiator with 1.4 W supporting VHBR and AAT) both have a cuttable antenna, so you can easily connect your own antenna.

Feel free to share more information about your application.

Rgds

BT

[Mc3]

Hi Brian,

Thank you for your answer.

The objective is to use an antenna that can be used for detection on X,Y,Z axis (I want to use Premo's Antenna).

I was interrested by the X-NUCLEO-NFC06A1 and X-NUCLEO-NFC05A1 board. Maybe there is something that I did not understand about matching circuit for antenna, but I thought that a matching circuit is designed for a specific antenna and if you change the antenna you should also change the matching circuit. Am I wrong ?

Thank you in advance for your help

Mathieu

[Brian TIDAL]

Hi Mathieu,

yes the matching circuit needs to match the antenna.

See application note AN5276 for ST25R3916 family (X-NUCLEO-NFC06A1)

See application note AN4974 for ST25R3911B family (X-NUCLEO-NFC05A1)

Rgds

BT

[Travis Palmer · Accepted solution]

Hello MC,

Be aware, NFC is a subgroup of RFID. RFID covers LF, HF ( =NFC) and UHF RFID applications.

It could be, that the coil you are looking at is for LF RFID. I looked at PREMOS Homepage and for for example the antenna 3DC12S.

It has a self resonance of ~400-500kHz which is way too less for HF RFID and an inductance of >2mH. We are recommending 0.2 - 2µH for NFC.

If you want to do a 3D NFC antenna, you can do your own wire-wound antenna. You can simply wrap a wire (e.g. 3-5 windings depended on the size) around an object (plastic cube) and then connect the antenna to one of our demo boards.

In general for this application we have two type of boards. The discovery board, which comes with a SW, GUI. It allows you to explore all the features of our chip, without doing any programming.

The X-NUCLEO boards are more the development boards. You can stack them on different Nucleo64 MCU boards and program your own applications.

We also provide an example SW for the X-Nucleo boards which you can adapted depending on your needs.

Both types of boards are available for ST25R3911B and ST25R3916 and all boards allow to solder a custom matching circuit.

Both ICs provide a differential output stage. This means, one antenna can be driven in differential configuration. It is also possible to connect two single ended antennas to the IC / demo board and switch between the antennas (e.g. X and Y antenna). To address a third (Z-antenna), either a second NFC IC would be required or the antennas are connected via a multiplexer.

I would like to point to a few useful application notes and tools:

AN5276 Antenna design for ST25R3916, ST25R3917 and ST25R3920 devices 

AN4974 Antenna matching for ST25R3911B/ST25R391x devices

AN4914 Automatic Antenna Tuning (AAT) of ST25R3911B/ST25R391x devices 

AN5322 Automatic antenna tuning (AAT) for ST25R3916 and ST25R3920 devices 

STSW-ST25R004 Antenna Matching Tool for ST25R NFC/HF reader family

br Travis