Hi Ian,
I am wondering why even bother with mesh wire. Radials provide a return
current path back to the feed point so current should mainly flow along the
length of the radial wires. Having shorts between the radial wires as a mesh
provides, would seem of little benefit. Any current flowing between radials
via the shorts would seem to result in loss current.
As to using any kind of steel material for radials the loss due to eddy
currents is going to be rather high, the same problem that steel antenna
wire presents.
Yes, steel radials are better than none, same as a steel wire antenna is
better than no antenna but for all the effort to put the steel wire in or on
the ground it would seem a much better case for copper.
> 1. Mesh grounds have multiple current paths in parallel, so the
> individual wires don't need to have especially high conductivity. What
> does matter in a mesh screen is that the individual crossover joints are
> reasonably good, to create those broad distributed current paths. For
> all those reasons, good-quality galvanized steel mesh can be quite OK.
>
> 2. Local soil chemistry is critical. Previous inhabitants at this QTH
> left behind some 'test samples' of old chicken wire that had
> disintegrated into sharp rusted pieces, ruining the ground for any
> further cultivation... which made me look for something else instead.
>
>
> What does work here is strong galvanized pig fencing, about 2.5ft wide
> and available in 150ft rolls. This material is made from heavy
> galvanized wire and has quite a large mesh varying from about 4 to 6
> inches. The mesh crossovers are rolled but the connections remain very
> tight, and after about 5 years under acid leaf mold the galvanizing is
> still good.
>
> Thinking about mesh size, 4-6in is not as bad as it looks. The usual
> mesh sizes of 1in or less are far smaller than is needed for HF. With a
> traditional fan of ground radials, we generally aim for a spacing on the
> order of 0.01-0.05 wavelengths at the outer edges, which on 80m would be
> well over 2 feet. From that perspective, a 4-6in mesh size isn't bad at
> all. Nearer to the base of the vertical radiator, the overlap between
> the rolls of mesh will also provide closer conductor spacings where they
> are needed the most.
>
> Where all the rolls of mesh meet at the center, they can be bonded
> together using these little gadgets:
> http://www.rappa.co.uk/products/151-four-way-line-clamp-25-pack These
> clamps are strongly made and heavily galvanized, so they can be cranked
> up tight to form solid cold-welded bonds, zinc to zinc. Again the same
> principle applies: apply cross-bonding in many separate places to create
> broad distributed current paths.
>
> Obviously a few rolls of mesh won't make an ideal ground, but at least
> they have made an *achievable* ground, in a location where traditional
> radials would have been impossible.
>
>
> 73 from Ian GM3SEK
>
>
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