Can we design Antenna for ST25TV which can be tuned for range ?

[vaibh_p]

Hi , suppose I am considering the reading distance of 10cm with my ST25TV tag .

So can we design Antenna for ST25TV NFC Tag IC such that the reading range can be configured in real time [For above case from 0cm -10cm] by means of some passive components ? i.e. we want to make the antenna for variable range which can be set using some componets.

[Berenice BENVEGUDA]

​Hello,

First of all thanks for your interest in ST25TV product family.

Then, could you explain a little bit more your use case so we can help you more accurately please ?

I understand you would like to make the reading range configurable, but how do you plan to configure it ? manually ?

Best Regards,

BB

[vaibh_p]

Yes we want to configure the "maximum range achieved" manually.

Moreover ST eDesignSuite provides the NFC Tag Antenna design reference for Square/Rectangular shaped antennas only , is there any other source which provides reference for Circular antenna ?

[Henry Crane]

​hi,

a good approximation of a spiral coil inductance can be found using Edesign suite calculator to simulate the inductance of a square coil whih side is equal to coil external diameter, and divide the result by 1.13 (approximate ratio between the surface of the disk and the sqaure containing it= sqrt(4/pi)).

You can also find various online calculators typing "spiral coil inductance calculator" in your favorite web browser. Among results, you'll find some tool allowing to calculate various shapes.

could you please explain what you mean by "maximum read range" configuration?

best regards,

Henry Crane NFC/RFID support team.

[vaibh_p]

Hi Henry ,

Any design reference or guide for Inductance calculation of CIRCULAR [All turns are of same diameter] Coil Antenna ?

I have tried on several websites , but most of them offer for Solenoid , which have one parameter of length , I tried with some negligible length value , but we didn't get the expected range .

[Henry Crane]

Hi,

sorry to answer to you with a question but I am not your to understand your need. do you plan to design a multilayer circular antenna similar to a solenoid, or a planar (spiral) coil?

Best Regards,

HC

[vaibh_p]

Hello Henry ,

We want to design antenna as shown in figure.

So we need reference for calculating the inductance of such antennas.

I guess this is one called as "Multilayer Circular Antenna" ?