TopBand: Radials

[Larry Higgins]

Here are a couple of questions which might stimulate some worthwhile
discussion.  Depending on the answers, they might also suggest some useful
radial system design info.

1.  It is well established that a whole bunch of radials reduces ground
losses.  However, often the available space precludes a radial system which
is less than optimum. If there is a particular direction either to favor or
to disfavor, is there a directional shift in the radiation pattern toward
the radials?  For example, suppose we want to favor northern paths, and the
available space is narrow north to south.  We might put our vertical as
close as possible to the south property line in order to have more radials
to the north.  Would this result in a directional pattern?  Obviously the
lack of radials to the south means higher system losses, but if we can
shift those losses to the least desired direction we can minimize the
effect of the losses.

2.  There has been much discussion about ground power losses with any kind
of radial system: above ground, surface, or buried.  Is there a way to
calculate ground losses for any given radial system, even approximately,
other than by installing the systems and then measuring the feedpoint
impedance?  Obviously it would be nice to have some idea of what to expect
before the installation work is done.  

3.  Kinda related to question 2: What kind of real ground results in the
best, or worst, efficiency?  If your counterpoise is sea water it
certainly has low loss.  But likewise, if the ground under your vertical is
a nonconductor, it will also have no loss because there will be no current
in it.  Somewhere between these extremes (my backyard, for instance) there
is a worst case.  Can we find and avoid this worst case?

73

Larry, N9DX  

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