Roy Lewallen wrote:

I'll accept your prediction. It doesn't seem to correlate with your
disagreement with Ian that the current into and out of a lumped inductor
are equal. You accused him of "mental masterbation" and being "seduced
by the steady state model" for even thinking such thoughts.

Yes, for center-loaded electrical 1/4WL mobile antennas, that is true.
You seem to be protecting the same sacred cow as Ian.

For the sixth time: If a loading coil is located at a current maximum
or current minimum point, the current into and out of the coil will
be approximately the same.

If a loading coil is located where the slope of the current is positive,
the current will actually increase through the coil.

If a loading coil is located where the slope of the current is negative,
the current will decrease through the coil. This is typical of center-
loaded mobile HF antennas.

Conventional circuit theory
predicts equal currents going in and out, so from your response I had
presumed that the fancier analysis would predict something else.

Not if the coil is located at a current maximum or current minimum point.
How many times do I have to say that before it soaks in?

You've also stated that the current shift through the inductor should
equal the "electrical length" of the antenna "replaced" by the inductor.
In this case, the inductor is "electrically lengthening" the antenna by
either about 45 degrees, or about half that amount, depending on how you
assign the effect of the mounting arrangement.

Nope, it isn't. You antenna is somehow already loaded and is equivalent
to a 50 foot unloaded antenna. Your feedpoint reactance should be around
+j370 for an unloaded antenna so you have about 27 degrees of extraneous
loading somewhere.

So in the past, you've predicted no difference, something like 20 or 45
degrees phase shift, or an indeterminate amount. It's good to see you've
settled on one figure.

There are three possibilities listed earlier. What happens with a coil
depends upon where it is located. Please read that over and over until
it soaks in.

My inductor was placed at the antenna base because I could measure the
currents there with reasonable accuracy.

Yep, you are looking for your keys under the streetlight because the light
is better there than it is where you really lost the keys.

On his web site, Yuri quoted W9UCW as measuring the currents at the ends
of a toroid mounted at the base of the antenna as being 100 mA at the
bottom and 79 at the top. You must, then, believe these measurements to
be in error.

If the toroid is not mounted at a current maximum point, i.e. if the feedpoint
impedance is slightly capacitive, then those figures could be accurate. I
didn't pay any attention to them. Could be his coil causes a larger phase
shift than your coil. You making your antenna too long ensured that
the current maximum point would fall inside the coil. Whether you realize
it or not, you are biasing the outcome of your experiment to agree with your
pre-conceived (sacred cow) notions.

Please note that I am not defending everything Yuri and W9UCW have said so
don't treat that set of three people as a lumped constant. I am not guilty
by association. My postings stand on their own merits or lack thereof.
--
73, Cecil http://www.qsl.net/w5dxp



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