Jim Lux wrote in
:

Lostgallifreyan wrote:

Thankyou. This is good, it sounds like the basic plan will work then,
and I might be able to get some chicken wire to cover at least part of
it.

Chicken wire rusts out pretty fast.. You'd probably be better off just
scrounging some AWG20 copper wire and improvising a little grid or
randomly laying it out.


True. Was just thinking that it's not that hard to find something meshlike so
even if it did it could be replaced for free. Given the price of scrap
copper, that rarely comes free these days.

One other thought... In that USMC antenna manual there is a mention of
something similar, a 15' whip tilted and also tied back so the upper
part is almost horizonatal, it's intended as a way to use short(ish)
distances for skywave propagation. It looks useful given the context of
trees and buildings within 100m of my best mounting point. What I'm not
sure of is whether the curvature of their tied antenna is relevant, or
a straight tilted whip would have no significant differences.

Curvature isn't "significant", and for a lot of cases, the tilt isn't
either. But, tying the whip back does keep it from whacking too hard on
low hanging branches.


In the case of a 15' whip, tilt might be. At least, if it isn't I have to
wonder why that USMC antenna manual was suggesting one for short-range
skywave use.
Document is "MCRP 3-40.3c" (PDF) 'Figure 4-34. AN/MRC-138 with NVIS Antenna'.
(About 4/7 of the way through that file, as gauged by scrollbar).

Where I am it seems the best chance due to surrounding buildings, trees,
fences, etc, is to use a slightly less exaggeratedly steep 'view' of the sky
than is implied by that description and drawing. If you look at that drawing
you can see that it isn't done to tie the antenna out of the way. There
seems to be specific reason for doing what they do there.

The curvature made me wonder, based on a relector, in an indirect way... I
read that a longer straight isolated rod placed directly behind a whip,
separated by a quarter wavelength, could be a reflector. While I guess any
curvature in either that rod or the whip might be insignificant at low HF, I
inferred that it had to be straight to work efficiently if the whip was
straight. There seemed to be implications that straightness, or lack of it,
mattered. That made me wonder if curvature in a whip (forget the reflector, I
have...) leaning toward a building might very slightly favour pickup on the
convex side and attenuation on the concave side, or have any other mildly
directional benefits. If so it might be a useful part of a strategy to reduce
noise from nearby buildings. Of course it might be useless trying, but it
looks like a nice idea...