Yuri Blanarovich wrote:

Oooops, carefull here.
As far as I know, nobody has claimed that inserted loading coil replaces the
"missing" degrees of the radiator in terms of providing magical properties
that would look like that "replaced" portion of the antenna, or make the
antenna act like 90 degree full size physical radiator.

Agreed, it's not quite stated as such. Here are some statements which
were made:

From your web page http://www.k3bu.us/loadingcoils.htm, in bold type:

"In summary:
The current in a typical loading coil in the shortened antennas drops
across the coil roughly corresponding to the segment of the radiator it
replaces."

By Cecil, on March 5, on this newsgroup:

"A loading coil thread is climaxing over on qrz.com. I have
used EZNEC to generate a graphic which shows a 3/4WL vertical
and a similar 1/2WL vertical with a ~1/4WL loading coil. The
loading coil is a wire helical coil containing (surprise)
roughly 1/4WL of wire. The coil does a good (not perfect)
job of replacing 1/4WL of wire. Many things can be gathered
from observation of the current reported by EZNEC for the
two antennas. The coil occupies roughly the same number
of degrees of the antenna as the wire it replaces. The
current at the top and bottom of the coil is roughly the
same as the current at the two ends of the wire it replaces.
Is the coil an exact replacement? Of course not."

What we are saying that the loading coil appears to replace "missing"
electrical degrees of the radiator in order to make it resonant, that is
back to 90 electrical degrees (has to be in order to resonant), which rest
of the existing "straight" radiator forces it to do (+/-).

It's getting muddier and muddier just what you mean by "replace". Nobody
has questioned that a loading coil makes the antenna resonant; that's
its purpose. But that's simply an impedance transformation property
which can be accomplished well away from the antenna by many different
methods.

Radiation
properties and efficiency of the loaded antenna is proportional to the area
under the current curve. It is obvious to anyone comparing the area under
the current curve of full size quarter wave radiator vs. loaded radiator
that there is huge difference in area under the curve and performance,
efficiency, which is known and been verified by numerous measurements.
HOW the current curve is modified by different loadings and position along
the radiator is important in knowing how the current distribution curve
along the radiator is modified.

I agree with all this. I'm glad you've clarified this for the benefit of
posters like the one to whom my recent posting was directed.

The whole controversy is that "gurus" claim current doesn't drop across the
coil, while we say that it does, therefore making the area under current
curve above the coil smaller and effciency of loaded antenna worse than they
believe and insist on.

I don't think you'll have any trouble winning your arguments against
your imaginary "gurus", whomever and whatever they might be. Over two
years ago I made careful measurements which showed a current difference
between the top and bottom of a loading coil. Cecil posted an EZNEC
model on his web site showing a substantial difference. I've commented
on it several times, explaining the reason for the difference, and
modifying the model to illustrate the explanation.

The controversy is in the explanation of the difference. It simply
doesn't require Cecil's theories. I've never been able to tell exactly
what your theory is, if you indeed have one.

Again, when applied in modeling programs, wrong assumption will produce
erroneous results, which will be magnified in multielement antenna designs.
So the "gurus" basically ignore behavior of coil in the standing wave
environment along the loaded radiator, where the current drops from max at
base to zero at the tip, but coil would magicaly resist that, because, bla,
bla, bla.... (see their "reasons")

Would you name these "gurus" so we can read their postings and see what
you're talking about?

So while everyone knows (?) that standing wave current drops acros (along)
the wire (all the antenna books show that), but it is "impossible" to drop
along the coiled wire (real inductance - coil, loading stub). Reality and
measurments prove that, but according to them "it can't be so".

I am already gathering necessary hardware to do more experiments,
measurements to show what is really happening, and will prepare articles how
to model and apply it to antenna design.
I would challenge the "unbelievers" to join me and repeat the tests, to see
wasaaaap.

You'll be surprised when everyone agrees that there's a current
difference between the top and bottom of the coil. Unless your "gurus"
show up, whomever they are.

I've already made a test and posted the results, over a year ago. When
it failed to show a current difference anywhere near the number of
degrees it "replaced", your complaint was that I was using an inductor
which was too small physically. So obviously your theory works only on
certain size inductors. Once you or Cecil has the theory fully worked
out, it should be able to not only tell us what the current difference
between top and bottom should be, but also how physically large an
inductor must be before the theory works. And why it doesn't work for
physically small inductors.

Those of us stuck with old fashioned conventional theory can explain the
drop for small as well as large coils, so you folks have a bit of
catching up to do.

I think a lot of the experimental work can be done by modeling. I'd be
interested in hearing of any cases where measured results differ
significantly from EZNEC results. Incidentally, your web page is a bit
outdated in that respect, apparently being written before EZNEC v. 4.0
was available with its automated helix creation feature.

Roy Lewallen, W7EL