If you would like a quantitative idea of the effect of increasing the radius
of a conductive ground screen take a look at figure 6, page 40, QST July
2000.
This is a graph of the percent of loss within a given radius normalized to
the total loss within a 1 wavelength radius for different vertical heights.
It is normalized for each height individually. In effect it tells you how
much of the total loss can be eliminated by a highly conductive ground
screen of a given radius. For example, for a 1/4 wave vertical, the graph
is quite steep until you get to a radius of least 1/8 wave or more. That's
why W8JI suggested earlier that you need at least an 1/8 wave screen to do
any good. Smaller screens don't save much. Dense radial systems are simply
a practical way to achieve a large radius ground screen.
73, Rudy N6LF
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