Is that normal practice to put card on top of reader during EMC testing?

[ALEX4108]

Hi,

I got some troubles when I put a Mifare card on top of contactless reader during EMC measurement. The 5th harmonics at 67.8MHz would be seen and  over the upper limit.

Without the card, the harmonics would be much lower. Even I put a metal plate or wire-ring on top of reader, I didn't see the 5th harmonics.

I just wonder if the harmonics was generated from the card and coupled to the reader to form common-mode noise.

Is it necessary to put the card on top of reader during EMC testing? If yes, any suggestion to suppress the harmonics? 

Thanks and regards,

Alex Poon

[Kan_Li · Accepted solution]

Hi @ALEX4108 ,

Actually it depends on the certificate you want to have, and normally a card/PICC reference is needed at some position to the reader. We provide a training video regarding EMC design for antenna design, please kindly refer to https://www.nxp.com/video/nfc-antenna-design-6-emc-related-design:ANTENNA-EMC-DESIGN-VIDEO for details.

Hope that helps,

Have a great day,
Kan

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