[Lowfer] Frozen trees ??

[Douglas D. Williams]

Which leads me to ask the question at what distance are trees no longer
detrimental to the radiated signal of a short LF vertical antenna?

I'm sure this depends on many factors, not the least being how large the
trees are, but as a rule of thumb, how far away from the nearest tree
should we try to get?

73, Doug KB4OER

On Mon, Jan 7, 2013 at 2:40 AM, JD <listread at lwca.org> wrote:

> >>> Everything I have read tells me I should lose current when temps are
> >>> freezing but I don't think my ground is a factor.
>
> Goes to show you can't believe everything you read! :)
>
> Seriously, not all soils behave the same under differing temperature and
> moisture content.  What happens at one location is not necessarily what
> will
> happen at another, either in terms of loss resistance or capacitance
> between
> antenna and ground.  However, I'm inclined to agree with you that your
> ground system may not be changing all that much in the circumstances you
> describe.
>
> (Just for reference, when you "lose current," is that even after retuning
> of
> your inductor?  And is there a pattern as to whether colder temperatures
> require more or less inductance?  I'm wondering whether the changes you
> experience are strictly a change in resistance, or in antenna capacitance,
> or both.)
>
> Your tree sap hypothesis is quite plausible!  As I think I mentioned in a
> previous LW Message Board thread where we were talking about tree-supported
> LowFER antennas, my experiences in Georgia led me to believe the same
> thing.
> Where deciduous trees could be used to support an antenna, there was a
> distinct difference in efficiency between summer (totally lousy) and winter
> (merely poor).  But with pines or other evergreens, the loss was there all
> the time, except maybe during the very coldest of weather...and I couldn't
> even be too sure about an improvement, because at best the signal was so
> poor it was never copied more than a county or two away.  That would be
> consistent with tree sap as a loss factor.
>
> I'd almost be tempted to suggest a Faraday shield for the trees.  I did
> something like that at a radio station once, though it was more for
> lightning secondary-discharge protection of a satellite dish than for RF
> reasons.  But it did seem to reduce the amount of RF current in the trees.
> There's almost no chance of it being practical where the tree is one of the
> supports for the antenna, though.
>
> John
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