[Lowfer] Henf / GAP antenna

[John Davis]

BTW, lest anyone thinks my expression of interest means I've fallen under
the spell of some "miracle" antenna at last, let me assure you that's not
the case.  Unless there's more on the missing page than I expect to find,
this one is nothing more than another heavily loaded electrically short
vertical.  Its only claim to fame is that its structure allows for enough
capacitive loading that very little inductance is required.

The inventor claims that this is the result of optimization of the ratio of
E to H fields (a conclusion arrived at through glaring errors of fact in
column 2).  On the other pages that are in the .zip file there are neither
math nor measurements to support this arbitrary supposition.  In fact, what
"math" is there tends toward the ludicrous.  Have YOU ever been able to
"decrease the resistance" of anything by "500%"?  I don't personally know
anyone who has ever decreased anything (except maybe their checking account
balance) by more than 100%.  If you can manage that trick, I expect you are
receiving unlimited amounts of energy from the quantum fluctuations of empty
space...which would certainly be a novel and patentable principle.

This antenna, though, is another rehash of well-known principles already
within the state of the art: increasing the diameter of the conductor that
makes up the antenna, attaching a large conductive surface on the end of it
to improve bandwidth and decrease the amount of inductance needed to
resonate it, and having another plate, ball, length of conductor, etc., at
the other end to complete the capacitor.  The only thing novel about this
antenna is the names that are stuck on the different parts of it to try to
make it patentable.  Blatant example:  "Moreover, the collector is
absolutely not a ground plane, although it might appear to be. It is the
lower portion or terminus of a physically shortened vertical dipole."  DUH!
If it looks like a duck, quacks like a duck, etc. ...

There's some real quackery in column 8, in the explanation of the
positioning of the inductor.  In this antenna, the inductor is at the top of
the mast, between it and the "collector" (the tophat-like
structure)--another well-known principle for improving the effective height
of the radiator by modifying the current distribution along the length of
the conductor.  But the inventor claims that by positioning the coil at the
bottom of the antenna, "the current on the mast underwent a 90 degreee phase
shift created by the inductor," thus causing the E and H fields to not be
properly aligned and resulting in a 3db reduction in radiated signal.  Yeah,
right.

It's too bad that patent examiners apparently don't have to be educated to
recognize the state of the art when they see it.  The same
principles...increased radiator diameter (although Henf appears to believe
he's creating separate E and H fields and crossing them, rather than
radiating from the mast), heavy end loading, uniform current distribution on
the radiator, and isolation of the displacement current from the physical
earth as much as possible...are found in scores of other physically short
antenna designs, patented and not, over the past hundred years.  The most
successful of these designs use all of those techniques in one form or
another.

It's rather like changing the gripping surface of the faucet connection on a
garden hose from a ridged circular shape to an octagon, then trying to
re-patent the idea of the garden hose itself by claiming it now works on a
whole new principle!

Anyway...having probably oversold my point a bit, I would say the patent
makes an interesting reminder of points one should consider in building
electrically short verticals, if one can overlook the bogus explanations.
Duplicating the antenna for LF per the specs in the patent is not likely to
be practical, though.

In what the patent calls the "preferred embodiment," the height would scale
to 262 feet for operation at 1750m.  Even at the smallest claimed length,
1/40 of a wavelength, the structure would be nearly 150 feet tall at LF, and
the top load (E field "generator") and ground plane ("collector") would be
cumbersome and expensive to build as well.  Furthermore, while it is
relatively easy to isolate the displacement current and the magnetic fields
in the "collector" from interaction with the physical earth in the 20m or
40m ham bands, the losses will be exactly the same at 1750m as any other
short aerial and counterpoise and the efficiency will plummet to levels we
are already accustomed to seeing.

Just today's reality check...

73,
John