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