On Sun, Feb 9, 2025 at 01:04 PM, Doug W wrote:
I am probably oversimplifying something I may not fully understand but is there a general rule of thumb for knowing if a material may be suitable? ? Such as if it measures x ohms per square cm or something like that.
The resistance of a flat surface is called sheet resistance, measured in ohms per square. Not square inches or square cm, just per square. After that, it looks like things get complicated. The amount of shielding depends on the conductivity of the shield material, its thickness, and the frequency in question. The reason is skin depth of RF currents, which varies inversely with frequency. They pay engineers good salaries to figure out the details.
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One alternative to painting on a conductive coating would be to add a metal coating to a plastic case using a chemical process called electroless plating or electroless deposition. There are YouTube videos of hobbyists doing it. Using copper or nickel metal, this ought to provide good RF shielding.
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It seems to me there is no easy solution for a hobbyist wanting to shield a plastic enclosure. That may be why the 4SQRP T41-EP kit used copper clad printed circuit board material for a case.
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73,
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Wes Plouff AC8JF
