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If one would enclose 5.8GHz transmitting omnidirectional antenna inside dry wooden block (wood would be cut to semi-precisely fit the antenna), how much it would attenuate the signal? (roughly)

And would coating the wood with lacquer worsen the situation considerably?

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  • \$\begingroup\$ the wood and lacquer are unknowns ... your best bet is to determine the attenuation experimentally. \$\endgroup\$
    – jsotola
    Jun 12, 2018 at 19:32
  • \$\begingroup\$ How thick is the wood? \$\endgroup\$ Jun 13, 2018 at 3:29
  • \$\begingroup\$ @analogsystemsrf Let's say 1cm. This is the average, in reality the enclosure would be about like this imgur.com/a/YFrI6Ec \$\endgroup\$ Jun 13, 2018 at 7:59

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Wood has a relative electric permittivity of 3 or 4 hence as soon as it closely surrounds the antenna, the whole electric field shape/magnitude would change and largely render the antenna useless at 5.8 GHz but make it more suitable for a lower operating frequency. There will also be significant losses in the wood but these are livable with but the change in permittivity won't be good.

would coating the wood with lacquer worsen the situation considerably?

Google the permittivity of the lacquer and consider also that the thickness will be quite small so, compared to the effect of the wood, the added lacquer might make a small worsening of the situation.

Just in case follow up questions are raised based on what-if this or what-if that, the precise solution that you may want is probably only accessible to an antenna simulation software package so don't expect follow-up questions like

"what if the wood was placed further from the antenna" 

to be answered.

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  • \$\begingroup\$ Thanks for the answer, I was suspecting that the surrounding wood would have more effects than just the attenuation. However that last bit was unnecessarily impolite, you could have just said that creating and iterating such a design is tedious work and really has to be done with some antenna simulation package. \$\endgroup\$ Jun 13, 2018 at 20:13
  • \$\begingroup\$ I can be a little direct sometimes! \$\endgroup\$
    – Andy aka
    Jun 13, 2018 at 22:46

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