> Dave, K1FK wrote:
> In vertical ground systems, it is most important to return the currents to
> the feedpoint of the vertical element by the most direct path possible,
> whereas screens comprised of many closed loops of mesh or chicken wire,
> etc., actually would return less current to the feedpoint. I believe
> extending a mesh field out to 1/8 wavelength or more would actually
produce
> poorer results than 30 or so radials of equal radius.
Mesh should probably be used only as a ground reflection enhancer under a
small elevated radial system, with the mesh connected to NOTHING.
Since the inverse square formula is at work here, regarding radial currents,
the current is the most concentrated at the base of the vertical. This
means that the radial return current concentration at the 2 foot radius is
only 1/4 the concentration at the one foot radius, 1/9 th at 3 feet, 1/16 th
at 4 feet, etc.
It would therefore be prudent to place sheet aluminum from the base out to a
3-4 foot radius, to spread out this current, shield radiation from the lossy
ground below the sheet, and avoid several dB of ground losses, for a small
radial system. The radials would connect to the outer edges of the aluminum
plate.
73, Doug / Nx4d
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