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Does a thicker piece of material(lets say metal) reflect wifi signals the same as a thinner piece of material?

I realise that thicker materials would block out more at the back, but my question is about the reflection.

I always thought it wouldn't but i have been challenged recently to think about this.

Thank you

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  • $\begingroup$ The phrase to search for is 'skin depth', the 1/e penetration of the wave at that frequency (it is frequency dependent). $\endgroup$
    – Jon Custer
    Commented Apr 24, 2016 at 16:14
  • $\begingroup$ I've made gold films that are thin enough to see through; they give a bluish coloring because some of the yellow is removed (absorbed). The gold is a normal reflector of light well before 200 nm of thickness, but is transparent at 100 nm. Though the thickness required depends upon the metal and the wavelength, if the metal is too thin one gets leakage. See skin depth for an RF skin depth calculator. $\endgroup$
    – Peter Diehr
    Commented Apr 24, 2016 at 18:19

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For a metal, a measure of how far the wave penetrates is determined by its skin depth, $\delta$. Typically $\delta \approx 10 mm$ for metals at around 50 Hz, but becomes much smaller at higher frequencies, at microwave frequencies $\delta \approx 1-10 \mu m$. This means that there's no point in having very thick metals.

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  • $\begingroup$ will these effects extend to other materials such as plastic or cardboard? also you seem to be mentioning penetration depth a lot, how does it correlate to reflection( sorry, i don't know all that much about physics) thank you :) $\endgroup$
    – John Hon
    Commented Apr 27, 2016 at 11:49
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Radio waves don't penetrate very deeply into metals. The depth to which they penetrate is characterized by a parameter called skin depth. The penetration is practically zero beyond about five times the skin depth, so adding additional thickness beyond five skin depths will make no difference.

The skin depth for most metals at 5 GHz is about 1 $\mu$m. So excepting very thin foils, thickness will have no effect.

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  • $\begingroup$ will these effects extend to other materials such as plastic or cardboard? and thank you and the others so much :) $\endgroup$
    – John Hon
    Commented Apr 27, 2016 at 11:44
  • $\begingroup$ Not for WiFi frequencies. Paper and plastics will attenuate the signal a bit, but they won't reflect to any significant degree. $\endgroup$
    – garyp
    Commented Apr 27, 2016 at 11:59

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