On Thu, 27 Jan 2005 22:20:15 +0100, "M. van Wijk" pa5mwremove
all(incl) between @home.nl wrote:

Hello,

I just moved to a new location. My backyard has some 20 trees spread around
at a distance of 5 to max 10mtrs between each of them.
I would like to opt for a full size 40mtr(7Mhz) vertical and have (only)the
2 following options her:

1) full size 1/4 wire vertical inside fishing pole, mounted in a tree at a
foot height between 7 and 10mtrs from ground level. Some 4 elevated radials
will be added.

2) full size 1/4 wire vertical at ground level, parallel to a tree at a
distance of 0.5 till max 1 mtr. Ground screen will be some 16 pcs of wire
buried in the surrounding ground.



I have no clue about any effects of trees here. They are not pine trees.
There are lots of other parameters in the whole picture, but the trees is a
totally unkown factor for me.

Please share me your experiences.


Dear Mark,

I thought no one had many trees over there. There's a rumour that you
make shoes from trees. Can't be so - would be damned uncomfortable.

Anyway, trees are bad news for verticals. They absorb too much of the
energy - the closer you are to the tree, the more energy is induced in
the tree and dissipated as wasted heat. There is no data on this that
I am aware of, but I would say the effect is similar to that of
surrounding your antenna with the wood rafters and sheathing of an
attic.

My recommendation would be to get your energy running perpendicular to
the trees to minimize that coupling and hope for the best. In other
words, in your environment a poor dipole would be better than an
excellent vertical. In fact, that's usually my position even without
the tree problem - Hi!

Bob, W9DMK, Dahlgren, VA
Replace "nobody" with my callsign for e-mail
http://www.qsl.net/w9dmk
http://zaffora/f2o.org/W9DMK/W9dmk.html