Coil Current Summary
 

John Popelish wrote:
. . .
The real revelation for me, from this discussion is how the concept of
"phase" takes a dimensional jump (from time to position) when you change
from taking about a traveling wave to the standing wave that results
from the superposition of a pair of oppositely traveling waves of the
same frequency.

Of course, we can speak of the phase (temporal or spacial) of any
periodic waveform. But it might be important to keep in mind that the
spacial amplitude distribution of a standing wave isn't generally
sinusoidal. When the forward and reverse traveling waves are equal in
magnitude, the amplitude distribution -- that is, the "waveform" if you
plot magnitude versus position -- is the absolute value of a sine
function. For all other cases, it's described by hyperbolic trig
functions. So the "jump" from time to position involves more than phase;
it also involves a change in waveshape.

Roy Lewallen, W7EL

Coil Current Summary
 

Cecil,

It is often entertaining to see someone switch positions and then claim
that's what he meant all along. (Yes, I am talking about you.) However,
I assure you that I am not "incredulous" about anything to do with this
topic.

73,
Gene
W4SZ

Cecil Moore wrote:
wrote:

This reminds me of the famous Fractenna Threads of years ago, where
Fractenna argued and argued, couldn't convine most people of anything,
and then declared himself correct.


What is really strange is that you believe what it "reminds you
of" is of technical importance. How about a technical rebuttal?
Guilt by association is an easily recognized diversion of the
issue. For the record, I argued with Chip as much as you did.
In fact, Tom, I always take your side when you are right.

Gene appears to me to be incredulous that you could possibly
believe there is any information at all in the standing wave
current phase measurement. Hint: There is none, just as Gene
asserts.

I suspect that Roy, W7EL, has discovered that same thing and
realizes that his standing wave current measurements, though
perfectly accurate, didn't provide any information that wasn't
already available from EZNEC or Kraus.

What I suspect is that neither you nor Roy realized that the
standing wave current phase is virtually constant from the
feedpoint to the tip of the antenna in a mobile antenna,
*whether a coil is present or not*. (When I reported the same
results as EZNEC, you implied my measurements were wrong.)
Roy said my measurements agreed with EZNEC. Is EZNEC wrong?

So when is one going to correct the errors on one's web page?
(Please note the use of the objective, third-person, impersonal
pronoun, "one".)

Coil Current Summary
 

You disappoint me Tom.
After reading what you wrote about a week ago about how bad it was some
years back
you have now reverted back to the old days. There is no need to smear
Cecil like you did with Chip. It will only poison the forum and force
you to leave again. Be nice
and don't get personal with those who do not fall in line with you
Art

Coil Current Summary
 

Roy Lewallen wrote:
When the forward and reverse traveling waves are equal in
magnitude, the amplitude distribution -- that is, the "waveform" if you
plot magnitude versus position -- is the absolute value of a sine
function. For all other cases, it's described by hyperbolic trig
functions. So the "jump" from time to position involves more than phase;
it also involves a change in waveshape.

Exactly! That's why the current waveforms through the coils
are not perfect cosine waves. To maintain the same forward
and reflected power, when the phase between the voltage
and current changes, their amplitudes must change accordingly.

Conservation of energy dictates that V*I*cos(A) must remain
constant (assuming no storage) so if the (A) angle changes,
voltage and current magnitudes must change accordingly.
--
73, Cecil http://www.qsl.net/w5dxp

Coil Current Summary
 

Gene Fuller wrote:
It is often entertaining to see someone switch positions and then claim
that's what he meant all along.

My basic position has been consistant for years and so
has Tom's. If you google the newsgroup from a couple
of years ago, I asserted to Roy that his standing wave
phase measurements were meaningless. I asserted that he
had measured the wrong parameter. Where were you?

Years ago, I indeed thought it was a simple problem.
I no longer think it is a simple problem. If that's
defined as "switching positions", then I am guilty.
--
73, Cecil http://www.qsl.net/w5dxp

Coil Current Summary
 

Cecil Moore wrote:
Cecil Moore wrote:

There is no useful phase information in standing wave
current. Therefore, standing wave current cannot be used
to determine the percentage of a wavelength that is
occupied by the coil.


Please replace the above with:

There is no useful phase information contained in the
standing wave current phase measurement. Therefore,
the standing wave current phase measurement alone
cannot be used to determine the percentage of a
wavelength that is occupied by the coil. The
standing wave current amplitude measurement does
contain some implied information about the underlying
forward and reflected waves, e.g. they are equal and
out of phase at a point where the standing wave amplitude
is zero.

How's that, John?

Much better.