Re: NEC-LIST: Modeling a living White Pine tree at HF

Prof Duncan Baker <dbaker_at_postino.up.ac.za> wrote:
>...I must confess, I think this is a curiosity. I sincerely
>hope we won't find a plethora of papers dealing with the differences
>between pine, poak, beech, pecan, etc etc species. I am of course
>open to arguments to the contrary.

My reason for asking how to model a living White Pine tree at HF was
that I, like very many ham radio operators, have a wire antenna
stretched between two trees -- White Pines in my case. Because the
distance between the trees is somewhat less than the length of wire I
desired, I contemplated "bending" the ends of the wires downward;
i.e., letting the ends of the wires hang vertically, between
insulators, near and parallel to the trunks of the supporting trees.
My concern was that if the tree trunks conducted too well, the
parallel antenna wires would induce too much current in the trees, and
thus dissipate excessive power.

Using George Hagn's estimate of sigma = 0.001 S/m for the tree trunks,
however, I have now calculated via NEC-4 that the tree loss for f = 7
MHz is just 1% -- trivial.

Thanks to all who contributed to this thread.

73 de Chuck W1HIS
Received on Thu Nov 23 2000 - 01:06:36 EST