[Fwd: LF: Losses]

André Kesteloot akestelo@bellatlantic.net
Mon, 18 May 1998 22:55:31 -0400

WarmSpgs wrote:

> On 98-05-18 Mike Dennison wrote:
> >At my site, the antenna vertical section runs just 2m from the house
> >and the horizontal section is supported at the far end (20m) by a
> >tree.
> >
> >Am I likely to get better results with a T antenna where the vertical
> >is away from the house? Bear in mind that the visual impact is much
> >greater so I would need a good reason to do this.
> >
> >I had assumed that trees / housing were not a problem at LF, compared
> >to HF or above. Am I wrong? I was certainly wrong about valleys being
> >transparent at LF.
>      These are certainly very good questions, and I don't know that there is
> an absolute answer.  Some trees seem worse than others in this
> regard...especially evergreens, which are the principal vegetation around my
> site.  Other operators, with different varieties of trees, have had
> surprisingly good results with 15m slanted wires suspended at the high end
> from a tree branch.  Talk about confusing the issue.
>      I had a choice of two antenna sites, one near the house and one near the
> trees.  The tree location afforded the opportunity for much better grounding
> and significantly higher antenna current.  However, the radiated signal ended
> up being the same in a few directions, and worse in most.  The antenna in both
> cases was a T, consisting of a 10m vertical section with a three-wire top
> section extending 5m both ways from center.  There are certainly plenty of
> opportunities for research into the electrical properties of vegetation at
> these frequencies!
> John