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I really begrudge the necessity of posting once more on this newsgroup,

and particularly on this thread. However, I’m dismayed and disgusted by

postings being made by Yuri and Cecil in other forums in which they’re

claiming that measurements I made agree with theories and predictions

they allegedly made, and that my measurements therefore validate their

theories. (A quick scan of this thread shows that they even made the

false claims here, after I had quit posting.)

One of the postings is the following, made by Yuri on the eHam TowerTalk

group, Nov. 21, topic “Trap Resonance”:

“Why don’t you mention what W5DXP came up as explanation for Tom’s

errors, why don’t you mention what W7EL measured and that it was what I

predicted based on available information and was right on – the 5%

difference for the base loading coil?”

and this one, posted by Yuri on the EHam.net forum topic “Re: Current in

Antenna Loading Coils” on Jan. 7:

“I will leave it here, as the rest of it. W7EL, author of EZNEC measured

toroid coil and found that it HAS different current at its ends, roughly

proportional to the part of antenna that it replaces.”

and this one, posted by Cecil on that same group on Jan. 12:

“Roy’s data clearly illustrates the phase shift through the coil.

ARCCOS(Iout/Iin) gives an estimate of the phase shift (assuming

forward current and reflected current are of equal magnitude).

In Roy’s experiment, Iout/Iin was about 0.95. ARCCOS(0.95) equals

18 degrees, an approximation for the phase shift through the


As you’ll see below (or by looking up the original thread), the first of

my two measurements, for an antenna shortened an equivalent of about 18

degrees, resulted in 3% current attenuation across the coil (not 5%),

and zero phase shift (not 18 degrees). The second test, where the

antenna was shortened more than 33 degrees, measured 5% current

reduction and no phase shift. The method used in the above quote

predicts more than 16% amplitude reduction and 33 degrees of phase shift

for the second test. There’s no way my data “clearly illustrates”

Cecil’s explanation. To say that it does is a pure fabrication.

I feel compelled to respond to these fabrications, and put the record

straight. I’ll do it here, since this is where my measurements were

originally posted.

I made two sets of measurements of the current into and out of a

toroidal inductor at the base of a vertical antenna. The details of the

measurement method and the measurement results were posted here, on this

newsgroup, on this thread. Pictures of the setup were posted on my web

site, with a link posted here.

Before I posted each set of measurements, I asked for predictions of the

results, so that alternate theories could be tested. (I was criticized

for doing this — it seems that the preferred method of testing a theory

is to look at the results first, then adjust the theory to fit.) Yuri

made a prediction (actually, two different ones) for the first set of

measurements that didn’t accurately predict the results. When I

calculated the predicted result for the second set of measurements using

the same method he had used for the first prediction, he retracted any

claim that the method would be valid. (Exact quotes are below.) He

didn’t make any prediction at all for the second set of measurements.

Cecil made a number of vague predictions which he later contradicted or

retracted. At the time the second set of measurements were posted, he

had made no prediction at all.

Perhaps Yuri and Cecil have, after the measurements were posted,

developed theories to explain the results. As of the time the

measurements were posted, they hadn’t. I highly recommend that anyone

considering their alternative theories to find where they have

calculated the results which agree with my measurements (particularly

the second one, which was designed to produce a testable difference),

and how they derived the equations used for the calculation.

Following is a summary of some of the exchanges between Yuri and me on

this thread last November. The entire thread, “Re: Current in antenna

loading coils controversy” and variants, is available for viewing at


   —— Summary ——

Here’s what really happened. The following quotes are directly from the

google archives of the rraa thread.

I made two sets of measurements. The first had the inductor connected at

the base of a 33 foot vertical. But the vertical was mounted about 1/4″

from a four foot pipe, which reduced the base reactance.

Here, I was asking for predictions for my FIRST measurement — the one

with the vertical mounted on the pipe.

Yuri posted on Nov. 9:

“In that case,

If the feedpoint current was at 0 deg of the radiator length, and coil

replaces 18 deg of wire, the cos 18 deg = 0.951 which should make

difference, drop in the coil current 5% (or half, 2.5 deg?)

Providing current maximum is exactly at the bottom end of the coil.”

and later on Nov. 9:

“>Incidentally, I take it that your prediction for the setup I did

 >includes an 18 degree phase shift of current from input to output of



 >Roy Lewallen, W7EL


Yes, I used Cecil estimate/calculation and taking

cos 18 = 0.951056516  which is 4.8943483%”

So now we have his prediction, using the “cosine rule”. The

I made showed about 3% current reduction from input to output, but with

about 2% (the same amount within measurement error) also occurring when

the antenna was replaced by a series resistor and capacitor — that is,

no antenna at all. So the 5% prediction was wrong. His prediction of 18

degrees phase shift, which wasn’t present, was also wrong. When asked

for the justification for the “cosine rule”, he never offered any, so

its origin remains obscure.

However, I saw that the value was too small to be convincing, which is

why I devised the second test. The second test used a more ideal

antenna, with more of the antenna being “replaced” by the inductor.

“cosine rule” would predict more than 16% reduction, and more than 33

degrees of phase shift.

Before I gave the results from the second measurement, I posted the

predictions which had been made, as I understood them. Since Yuri had

invoked the “cosine rule” for the first test, I naturally assumed it

would also apply to the second. (This is simply applying the equation

Yuri used in his Nov. 9 posting to the second antenna setup. It’s also

the equation now being used by Cecil, as shown in his quote from the

eHam group.) So in my posting I said:

(Quote from my posting on Nov. 11):

“**Yuri’s method predicts a reduction of output current magnitude of

16.5% and a phase shift of 33 degrees.”

to which Yuri responded, also on Nov. 11:

“It is not my theory. My argument with W8JI and his followers: is the

current in typical loading coil in quarter wave radiator same at both

ends or does it drop with distance from the feedpoint. I have made

temperature observations, W9UCW measured the difference, W5DXP provided

some explanation. Based on Cecils analysis of data you provided, and on

my understanding of the phenomena I guestimated drop in current in your

setup. No theory, no mathematical procedure (yet) just attempt (using

degrees replaced by coil in a radiator) at explanation of what is

happening. I will measure things myself, try to verify previous

measurements and then come up with conclusions and “theory”. So far

Cecils (and ON4UN book) theory seems to be closest to the truth. . . “

So now, Yuri has disclaimed the “cosine rule”. /He made no other

prediction of the results of the second test./

In summary, Yuri first stated that the “cosine rule” can be used to

calculate the current drop. That would have predicted over 16% current

reduction in the second test. Then he retracted his claim that that

theory would work, before the results from the second test were posted,

and never made any other prediction. He never predicted the 5% result

which was measured, as he’s now claiming.

And if you can find a numerical prediction anywhere in the thread which

Cecil made and stayed with, my hat’s off to you. $100 goes to the first

person who can point to any prediction made by either Yuri or Cecil

before the second measurement results were posted that predicted second

measurement results of 5% magnitude and zero phase shift. (In the case

of Cecil, this would have to be a prediction that wasn’t later modified

or retracted before the second set of results were posted.)

My measurement results are consistent with the fact that the currents

into and out of a physically small inductor are equal. The small

magnitude difference I measured can be explained by stray capacitance on

the order of 7 pF from the output to ground and/or the probe — not an

unreasonable amount to expect. In no way do my measurements support the

odd theories being proposed by Cecil and Yuri, and any statement that

they do is completely false.

Roy Lewallen, W7EL