On 12/29/11 10:33 AM, David Jordan wrote:
> Bravo Jim... finally the answer... it don't make enough difference to type
> two sentences about it. Move that wire away from the tree trunk and hang it
> from a limb and BINGO... you got an antenna that works good enough for most
> folks; sure beats no antenna doesn't it;(?)!
>
> 73,
> Dave
> wa3gin
Well.. it *is* nice to know that at least the trunk isn't going to cause
huge problems. And it's nice that the back of the envelope intuitive
analysis seems to match the simple finite element model.
(and it's also nice to know that the 6BTV that I put up a few weeks ago
in amongst the trees will probably work fine, when I put it back up..
blown down in the wind)
There's still an issue of "antennas in a forest", which is intriguing,
because it seems to say that a lowish horizontal dipole among the trees
might be better than hanging a vertical. Again, useful to think about
when talking about stealth antennas.
and the question of leaves. I'll have to hunt down some info on leaves
(particularly wet leaves)..
But I'd think, if you're clear of most of the foliage (and the antenna
isn't touching the leaves at the high voltage end... yep, been there,
lit the tree on fire with 100W)
An interesting modeling question is "what effect does modern house
construction have"... I've got my dipole laying on top of my concrete
tile roof. Works fine most of the time, but when it's wet, it's
noticeably worse. But if I were to go to the trouble of suspending the
wire, say, 6" above the roof, would that help? Or do I need to go to 1
foot. (That's not an antenna, that's a wire to keep the pigeons from
roosting up there...)
Or the perpetual question you see: I have a vertical (x-BTV, R7000,
GAP, 43 foot untuned, whathaveyou) and I want to put it 3 feet from the
house in the side yard. Good, bad, indifferent? Just how bad?
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