Pine trees taller than 100 feet could be an issue, since they could be
near resonance and lossy - a sad combination when within a wavelength or
so of vertically polarized antennas. If your trees are 50 footers, they
would probably not be of concern on 160m, but could be on 80m. For
horizontally polarized antennas, the trees aren't a problem.
Years ago, when some fellow proposed that trees would radiate because they
were fractals, I measured the RF resistivity of freshly-cut pine trees. I
firmly attached copper or aluminum plates to a thick one foot long trunk
section, and measured resistance. These were wet, freshly-cut, sappy, pines.
Pines are acidic and very wet inside, so they should reasonably be at the
top of tree conductivity.
I can't recall the exact RF resistivity, but I'm pretty sure it was either
high hundreds or low thousands of ohms per foot for a one foot diameter log.
I do know the number was significant. Resonance, significant absorption, or
radiation would be impossible with that much resistivity per foot.
Given a choice, I probably wouldn't have a high voltage area in close
proximity or contact with a tree. I doubt a few trees would produce
noticeable loss, and they certainly could not be by any stretch of the
imagination "resonant" with such high resistivity per linear foot.
73 Tom
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Stew Perry Topband Distance Challenge coming on December 29th.
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