----- Original Message -----
From: "Dave Bowker" <dbowker@mail.sjv.net>
> Gary, K9AY is quite correct in his response that [copper] mesh used as an
> artificial ground at HF and VHF has proven quite effective and that radar
> and satellite antennas use perforated reflectors to save weight [I presume
> Gary is refering to aluminum mesh reflectors in this case due to weight
> concerns].
Skin depth for zinc is ~.0035 inch at 1.8 MHz, so there will be some
benefit due to the galvanized coating depending on its thickness (but
probably not too much). Also, eddy currents would generally be the
result of magnetic field lines that are perpendicular to the plane of the
mesh as closed eddy current loops in the mesh structure would produce
magnetic fields lines perpendicular to the current loops whereas the
magnetic field lines in a ground mounted vertical are generally in the
plane of the ground system (at least that's my understanding - I =
n X H).
The real killer may be the increased path length for the return current as
it has a sideways component due to the non-radial arrangement of
the wire in the mesh. Thus return currents will have to wiggle back and
forth towards the feed rather than flowing in a straight line as they would
in a true radial wire.
73 de Mike,
W4EF...............................................................
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