How must i desing CR95HF antenna

[cdoga]

Hello,

I designed a PCB with CR95HF mifare chip, you can see at photo2.JPG

and you can see my antenna phisycal dimensions and equivalent inductance at photo3.JPG

at eDesing suite it dont seems a right antenna desing. gives warnings.

and you can see my antenna circuit schematic at photo4.JPG

with below informations can you say me components values at my antenna circuit schematic at photo4.JPG .

if this antenna desing wrong, do you prefer me antenna desing at photo1.JPG?

if prefer ptoho1.JPG desing, do you say that; how must i choose component values and which components must be ? could say component values?

Thank you, bye.

[Brian TIDAL]

Hi,

I would suggest to have a look on Application Note AN5248 ST25R95 transceiver antenna tuning circuit with EMI filter (for ST25R95 or CR95HF products)

Rgds

BT

[cdoga]

Hello Brian,

I have AN5248 application notes but i didnt achieve to calculate right component values with app formulas.

I have only L0 value(equivalent inductance).

So i calculated some values and i tried it but i didnt get right results for antenna. i didnt catch 13 MHz signal.

If you have any help chance we will use this chip 10.000 per year.

I didnt get any technical support. Could you have any chance to say about how can i get technical support?

[Brian TIDAL]

​Hi,

you can contact your local ST sales and marketing representative to have support from ST Field Application Engineers.

Regarding AN5248, make sure to use the STSW-ST25R003 ST25R95 EMI filter calculation tool to easily compute the different values of the components. As your PCB has an important ground plate, the real electrical characteristics may differ from the theorical ones, so it is recommended to measure the actual inductance and impedence of the antenna and then use those value in the calculation tool.

The antenna size is quite important. This may have some impact when reading tags having small antenna (in particular at the center of the antenna). Can you share more details about you aplication and about the tag characteristics?

Other feedback from our RF expert: There is not so much room between the antenna and the blue part. Having more room would improve the performances. Make sure to have via between the ground planes.

Rgds

BT