Richard Clark wrote in
:

On Tue, 05 Jan 2010 12:49:38 -0600, Lostgallifreyan
wrote:

Ok, copper's no problem, was just wondering about stuff I had plenty
of at hand.. I wish I had a lawn. I was thinking that it would be
an ideal method. My main difficulty (apart from a large amount of
heavy logs (and most of a tree trunk) is that the best place to mount
the antenna is in a far coner of a plot so I can't lay radials all
round it.

Running a fan of 90 degrees is fine, there's nothing exact about this
except for those who imagine they will suffer the dB of
out-of-symmetry.

I can probably get the permission of one neighbour to run a ground
wire along the far end of his garden along a low wall, but that same
wall is a high wall on the other side, there's a drop of several feet
as well as no chance of permission to lay wires there.

Don't bother. It isn't worth anyone's effort or intrusion.

This is why I'll want a
ground rod, as a tree used to grow there, the rotted roots might be my
best chance of anything like a conductive network that is close to the
surface, in addition to a few ground wires.

A wire mesh or mat (like chicken coop wire) over the surface of that
area would serve far better. That doesn't sound like an option so the
matter of pursuing conductivity of rotted roots is an illusion.

I'm a tenant, I don't own
the land, and can't do much except work round what is there.

You'll be able to do enough without much impact.


Thinking about what I read recently, it seems that if the whip is not
vertical but slightly leaning back over the plot of land toward the
houses, it will have a better chance of using the sky waves, but what I
don't know is whether that demands ground radials to be biased (if
biased at all) to favour coverage on the side the antenna is leaning
over, or the other side. My guess is the side it's leaning over... Is
this true? If so, it will help a lot to make the best of that space.

Your gain/loss advantage will be in the direction from the antenna
base out along of the middle radial in a 90 degree fan. Leaning won't
significantly alter things for a very short antenna (in terms of
wavelength).

Now as to these advantages and disadvantages. Once you get to a
minimun set of radials (call it four), the addition of more wire won't
budge your S-Meter more than a needle width (and that is being
generous). The addition of more radials concerns establishing a firm
reference of ground for Z.

73's
Richard Clark, KB7QHC


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. One
possible complication I didn't mention is that the intended mounting point is
at a T junction of three wire mesh fences of equal height, about 6'. They
don't have very reliable conductivity between each zigzag strand (oriented
vertical) as at least one fence has a green plastic coating on its wires. I
intend mounting the whip on a concrete post at the junction of these fences.
I imagine the fences will raise (and make diffuse) the precise physical level
of the RF ground, but I don't know whether they'll be a serious problem, or
maybe even be helpful. I can try grounding them a bit better, but otherwise
there's not a lot I can do about them.

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.