DIYbanter - View Single Post - Contactless cards again! [OT in uk.d-i-y]

F Murtz

wrote:
Andy Wade wrote:
On 20/05/2013 18:00, Martin Brown wrote:

Probably needs to be a sandwich of mu-metal inside copper inside silver
to get maximum screening in minimum thickness.

Looking at BS ISO/IEC 14443-2 reveals that the operating frequency for
these cards is 13.56 MHz - one of the ISM 'free-radiation' freqs.

Hence low-frequency screening techniques such as mu-metal aren't
particularly relevant. Wrapping the card in aluminium foil ought to
work fine. Ideally all the seams should make good contact, but you're
not looking for a particularly high screening factor and more or less
any sort of overall wrap ought to do the trick.

At 13.56 Mhz the wavelength is something around 20 metres so any sort of
mesh with holes much smaller than that (hardly difficult!) would screen
it very effectively.

Aluminium wallets are sposed to do the trick.
http://www.ebay.com.au/sch/i.html?_nkw=aluminium+wallet