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As I know, lead can block a half of X-ray. But I don't know that can lead, silver and gold block the low radio frequency. I am trying to use lead, silver and gold to block the NFC radio frequency https://en.wikipedia.org/wiki/Near_field_communication

Can silver, gold and lead block NFC radio frequency?

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Yes, basically any conductor will affect radio frequency EM waves. A key parameter to look at is the skin-depth $\delta$:

$$ \delta = \sqrt{\frac{2}{\omega \mu \sigma} } $$

($\omega$ is the angular frequency, $\mu$ is the magnetic permiability of the material, and $\sigma$ is the conductivity of the material). As long as the material is thick relative to this length scale, it will seem opaque. Using the skin depth calculator here I get a skin depth of $0.7\mu m$ for $13.56MHz$ radiation.

What you're looking to do is create a Faraday Cage -- and there's a few design trade-offs between the thickness of the conductors and the size of "holes" in the cage with respect the frequencies you are trying to target. For this application you do not need high atomic number materials, like you would for high energy (X-ray etc.) applications. The main consideration is the bulk conductivity (and magnetic permeability) so I'd expect that you'd find aluminum or copper as more convenient and less expensive.

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    $\begingroup$ but you do need it totally surrounding your receiver, or the source, as it'll diffract around edges pretty good. Hole sizes or gaps just need to be less than say a tenth of the wavelength, shouldn't be a problem at low freqs. And for Al the skin depth is closer to 20 micro meters, because of a higher resisttivity than say gold. Still small enough. $\endgroup$ – Bob Bee Mar 15 '17 at 0:13

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