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