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RF absorber(shield) for 13,56Mhz and 125kHz

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mystery

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Hi all,
I have some RFID readers both at 125kHz and 13,56Mhz. I want to shield the backside of the reader. So no RF signal should be emit from backside of the reader, just front. I checked the site : http://www.ferrishield.com, but there seems no suitable products for the desired frequency.

Any idea or product, to shield it. Thanks for your help and interest.
 

elmolla

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Why don't you just use a copper sheet? 1cm thick copper sheet will be good
at 125 khz, the skin depth will be about 0.02cm.
 

    mystery

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biff44

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Since many RFID antennas are magneticly coupled coils, you might try a magnetic shield. Copper will not stop a magnetic field. You want something called Mu Metal.
 

    mystery

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sergio mariotti

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biff44 said:
Since many RFID antennas are magneticly coupled coils, you might try a magnetic shield. Copper will not stop a magnetic field. You want something called Mu Metal.
Yes, Copper has µr=1 while µMetal has µr very high, but don't means that Cu cannot shield magnetic field. It depend how the shield is made, i speak about geometry of the magnetic circuit.
A properly designed, copper made, short circuit closed ring, may efficientely shield the your device.

I agree about the copper thickness... 2 to 5 times the skin depth.

µMetal, is a non-practical alloy. It should be cutted, folded, drilled BEFORE the magnetic grain oriantation. For this reason, only a factory may produce a formed µMetal sheet.
 

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