Pete Smith wrote:
> My local farm supply store has rolls of welded steel wire mesh
> (galvanized) with 2 x 4 inch openings, for what seems like a pretty
> reasonable price per square foot. I am tempted to use crossed strips of
> this stuff at the base of my shunt-fed tower in an effort to reduce
> ohmic losses on 160 and 80 meters, tying them together with split bolts
> and by wire to the plate that terminates my longer radials.
>
> First, I'm wondering if those openings are small enough that the mesh
> would appear at those frequencies to be equivalent to solid sheets of
> steel? And if so, would such an addition to my radial system make
> sense? I was thinking of either 4 x 25-foot strips or 2 x 50 footers.
>
Hmm.. my first thought is "try it and see" because it's hard to predict
what this will work like.. Here's some thoughts though:
steel is not a particularly good conductor, but on the other hand it's a
heck of a lot better than soil, so it's probably a net gain
I don't think the openings are significant as openings (they're such a
tiny fraction of a wavelength, but you could probably model it as a
continuous sheet, with conductivity scaled as (fraction covered by
steel)*conductivity of steel. Ditto for permeability.
On the other hand, it might actually be better than that. Sort of like
chicken wire is a pretty good reflector at 4 GHz, even though the
solidity is tiny. However, this is for a propagated wave.
Looking at the base of a tower, I think you're more in a near field
situation, which is why I think the "fraction of area covered" might be
more appropriate.
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