Looking for a suitable antenna for ST25R100-CMET

[vibrao]

Updated the title to be inline with ST community rules.

Hi all! So I am looking for a standard antenna which would be suitable for ST25R100-CMET (IC Reader 13.56MHZ 24 UFQFN). This will be used in an alarm module with a lock, so please suggest! Thank you!

[RobK1 · Accepted solution]

1. Go to the Digikey website
2. Type "RFID Antennas" in the search field
3. Select the appropriate frequency
4. Take your pick

[Travis Palmer]

Hello Vibrao,

there are different type of NFC antennas.

• The most common type are PCB antennas. So basically traces on the PCB are used as a coil. Most of our EVAL boards are using PCB antennas (e.g. STEVAL-25R300KA) 
• Another type are wire wound antennas. A piece of wire is being used as a magnetic loop antenna
• Also quite common are Ferrite antennas. If you are following RobK1's proposal (thanks for that) you will most probably find them. The coil itself consist of traces on a flex PCB. to be less impacted by environmental changes, a ferrite layer is applied on one side. 

Typically the NFC antenna is defined by the available space and is chosen to meet the performance criteria. 

The good news is, that our ST25R100/200/300 devices can be used with all of them. 

I would recommend you the following application notes for further details about the antenna matching:

• AN6065 Antenna design for ST25R200 and ST25R100 devices
• AN5592ST25R single ended antenna matching (also applicable for ST25R100)
• AN5984 Layout recommendations for the design of boards with the ST25R200 device

Please let us know, if you have further questions!

br Travis