Rick, your observations generally agree with mine on NVIS antennas of any sort;
whether dipole, inverted V, or loop, over very reflective ground. The
experiment I observed used roughly 100,000 square feet of aluminum sheets laid
with overlapping edges on very conductive earth. At some heights and
frequencies signal strength was substantially enhanced, at others it was just
as substantially reduced. Just as both published theory and a little thought on
reflections generally says it should.
But my distaste for low horizontal loops is pretty simple. Besides the extra
complexity that makes a large horizontal loop a problem with a postage stamp
size city lot - and the further complexity that our water table and therefore
the actual reflecting ground layer varies by nearly 40 feet, call that 10
Meters, depending on how long it's been since the last rain and how much water
has leaked out of this hill.......
North America is a huge place. And from here, I have a pretty good reach of
uninhabited water to my south. So it is a long way to the areas with a really
high ham density.
A low dipole or an inverted V has enough low angle radiation to make a fairly
effective antenna over most of NA - and the world when conditions are average
or better. But a low horizontal loop is a little TOO directional.
Taking 80 Meters for an example, 100 miles from here a loop at 25 feet, 8
meters more or less, is usually much the better antenna. 500 miles from here,
St. Louis or Charlotte or Tulsa, 19 nights out of 20, the dipole or inverted V
is the better antenna. And a vertical is a better antenna still.
For one instance of many, one night a few years ago I worked EI8S with 5 watts
on the GAP Voyager vertical, switched antennas and got the same signal report
with 50 Watts to the dipole. But he was inaudible on the 260 foot loop fed with
450 ohm ladder line I had up before they cut the trees I was using for
supports. So I'm back to a shortened dipole and a vertical. And frankly, I
don't miss the loop at all.
So it appears that one size does not fit all, any more than one suit fits all
occasions.
73 Pete Allen AC5E
They are a little too directive.
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