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From what I could gather after a quick search on the internet, it would seem that any material can reflect or absorb RF waves but thickness matters. It's obvious that most parabolic dishes are made out of a metal so metals must be better at reflecting RF waves compared to other materials. My questions are:

  • What physical effects are taking place here to produce a reflection? What type of compound would reflect RF waves the best?
  • How much does smoothness or uniform thickness of the material affect its ability to reflect?
  • What theories/equations help us predict the effects of these factors?

Edit: Originally I mentioned thinking about building a parabolic dish, but I removed that part since it's not really relevant to the question.

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    $\begingroup$ What's wrong with aluminum? Look up the skin depth at your frequency, make the metal several times as thick and you are done. $\endgroup$ – CuriousOne Apr 9 '16 at 0:40
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    $\begingroup$ Aluminium would probably be the best solution for a hobbyist like me, but I am curious as to if there is a hierarchy of materials in terms of relative reflectivity for radio waves, and I am curious as to what the theory and equations behind this are. $\endgroup$ – hololeap Apr 9 '16 at 0:45
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    $\begingroup$ Look up "skin effect", that's pretty much it for metals and RF work. It's unlikely that you would ever want to use anything else than aluminum, unless you have very special requirements? Silver and gold plated copper might do nicely, as well, at hundred times the cost and probably without any appreciable difference other than maybe a Trump factor, or two, you know... for those people with "yuge" hands... :-) On a more serious note, the other end of the problem, materials that absorb and scatter radiowaves, that's much harder. $\endgroup$ – CuriousOne Apr 9 '16 at 0:54
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    $\begingroup$ The derivation of skin effect contains the entire math that you need. There is nothing more "substantial" than that. You solve Maxwell's equations for the transition from free space to a conductive material. Inside the material there is an exponentially dampened wave and outside, because of energy conservation, there has to be a reflected wave. $\endgroup$ – CuriousOne Apr 9 '16 at 1:19
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    $\begingroup$ Note that skin effect depends on conductivity and permeability. So you want a good conductor with low permeability. At 1 GHz only the first few microns matter and gold coating can be quite effective. Non corrosive properties help - even a thin layer of oxide will affect performance. Which is where gold beats silver / aluminum etc over time... $\endgroup$ – Floris Apr 9 '16 at 2:33
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A layer of two materials. The layer should block both EM waves. Electro and magnetic. Iron responds to magnetic well, while copper responds to electrons well. Layer such that the skin depth is sufficient such that eddy currents are attenuated and do not penetrate the material. The thickness and order of the layers should balance weight, cost and performance.

I would suggest rapid prototype layer of iron and copper sheets.

Skin depth: https://ecee.colorado.edu/~ecen4634/Chapter%2020%20-%20The%20Skin%20Effect.pdf

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