On 12 Jun 2007 at 10:43, James Moritz wrote:
> It has often been said that trees surrounding an LF vertical antenna
> can be responsible for a substantial proportion of the antenna loss,
> and at my QTH there are several trees that have gradually been
> getting bigger over the years, so I decided to try to measure how much
> RF current was actually flowing in some trees.
Rather interesting Jim. There are a couple of leylandii which the
previous neighbour planted in his garden a few years ago, and which
are growing at an enormous rate of knots. See
http://www.davesergeant.com/qrp/160vert.htm (photos taken in 2005).
The left hand tree, behind where the vertical is, is just a couple
of metres or so from my vertical and suspect is absorbing quite a lot
of my rf. It might also be related to the enormous 300 ohm earth loss
resistance I seem to have...
I have a theory that it is actually working like some sort of
reflector. I have excellent chats with Chris G3XIZ in Biggleswade (to
the north) whereas the Kent boys (east and similar distance) just
about detect me in the noise. I have not heard anybody to the south,
through the trees, yet.
Maybe there is more about leylandii than we know!!
73 Dave G3YMC
http://www.davesergeant.com
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