wrote:
Before I comment on your posting below, I think you can prove
to yourself that your measurements are flawed. You measured
3 nS delay through your coil at 4 MHz. Now perform the same
measurement at the self-resonant frequency. The delay through
the coil is known to be 15.6 nS at the self-resonant frequency.
If your delay measurement isn't 15.6 nS, then there is something
wrong with your methods. Better yet, measure the delay at 1,
2, 4, 8, &16 MHz and report the results.
... it is unlikely anyone can prove Cecil wrong.
That's because in order to prove me wrong, you have to prove
yourself right. You simply haven't done that because you refuse
to engage me at a technical level. You have ignored my technical
questions and refused to discuss the technical details. Many
readers have noticed that, wonder why, and have commented on
it in emails to me.
This all seems logical to me, because Cecil has asked for measurements.
The pattern has been after he gets measurement results and finds they
disagree with his theory, he has to blame the difference on something.
Tom, your measurements agree perfectly with my theory. You are
measuring standing wave currrent. That standing wave current
magnitude is pictured in every good book on antennas. Kraus
also shows the phase which, for a thin wire dipole, is fixed
at zero from tip to tip on the antenna. It is understandable
why you measured zero standing wave current phase shift through
the coil. THE STANDING WAVE CURRENT PHASE SHIFT IS ZERO WHETHER
THE COIL IS IN THE CIRCUIT OR NOT!
Since the phase of the standing wave current is fixed and
unchanging whether the coil is in the circuit or not, why do
you think measuring that unchanging phase around a coil proves
anything?
I proposed antenna losses were swamped out by ground losses in a
vehicle, and because of very high ground losses the effects of coil
resistance were diluted.
I agree with that and have never argued otherwise.
I measured the inductor and found as quite logically anyone would
expect that current ratio depended on the ratio of stray C from the
coil to load C at the open end of the coil. Yuri K3BU argued the coil
replaced a certain number of degrees electrical height, and I
disagreed.
The following reports a 10-20 degree phase shift through most coils.
http://lists.contesting.com/archives.../msg00540.html
Most people experienced in systems like this from an engineering
standpoint agreed with me. Somewhere about that time Cecil brought
reflected waves into the discussion.
Those "most people" don't understand forward and reflected waves on
a standing-wave antenna. You have proven by your postings here that
you do not understand forward and reflected waves on a standing-
wave antenna like a 75m bugcatcher mobile antenna. Worse yet, you
refuse to discuss the antenna at a technical level and have simply
sandbagged your misconceptions.
I remember when you were using the lumped inductance feature of
EZNEC to try to prove your point, certainly an invalid proof. When
we started this thread, it was obvious that you didn't know the
standing wave current phase is fixed near zero degrees so measuring
it is futile.
After a series of "what happens if" Cecil wanted measurements. When
they were made, he and Yuri announced the measurements proved their
points.
Yes, they did prove that the current at the ends of the coil were
NOT equal. You said they were. I said they were not. Out of all of
your and Roy's measured results, the current was equal in only the
case of the small toroidal coil and that's because it was located
at a standing wave current maximum (loop).
When the person making the measurements corrected those
misstatements and pointed out the measurements didn't support their
claims, the only logical course was to discredit the measurements and
ask for new ones.
You sure have selective memory, Tom. I fully accepted your standing-
wave current measurements. But standing-wave current measurements
cannot be used to measure the traveling-wave delay through a coil.
That should be obvious to everyone by now. The delay through the
coil causes a phase shift in the forward wave and the reflected wave,
not in the standing wave. THE PHASE OF THE STANDING WAVE CURRENT IS
KNOWN NOT TO CHANGE AND THAT'S EXACTLY WHAT YOU MEASURED, VIRTUALLY
NO SHIFT.
Kraus agrees. Figure 14-2 of "Antennas For All Applications", 3rd
edition shows a graph of the phase of the standing wave current.
That phase is zero tip-to-tip for a thin-wire 1/2WL dipole.
When new measurements again disagreed with the concept of huge current
or phase delay of current that was tied to degrees the coil replaces,
the only course was to reject those measurements.
THOSE MEASUREMENTS WERE NOT REJECTED! They were accepted as perfectly
valid measurements of standing wave current. Those characteristics
are pictured in Kraus and your measurements agree perfectly with them.
Your argument is a strawman. The fact is that a standing wave measurement
CANNOT yield the current delay through the coil any more than it can
yield the current delay through a wire. YOU CANNOT MEASURE THE DELAY
THROUGH THE COIL USING CURRENT KNOWN NOT TO CHANGE PHASE!
So here we are today, two or three years later, still trying to find a
measurement that will agree with what Cecil and Yuri proposed or for
another person of reasonable engineering experience to agree with the
notion the coil behaves as a coiled up antenna or transmission line
rather than behaving more like a lumped component in a small heavily
loaded mobile antenna.
This is not about you or me or Yuri. It is about getting down to the
truth. Yet you rave on and on about personalities. Why don't you
discuss technical issues instead of personalities?
There is a phase shift in the forward current through the loading
coil. There is a phase shift in the reflected current through the
loading coil. Those phasors are rotating in opposite directions so
the net phase is fixed. You can measure standing wave current phase
in thousands of experiments from now to kingdom come and you will
not be measuring the phase shift of the forward and reflected
current through the coil. Your measurements, so far, are meaningless.
You have NEVER measured the delay through the coil.
I guess I'm going to have to draw you some pictures and post them
on my web page.
Since dozens of hours of measurements acceptable to most people were
rejected, the only solution would be to require a measurement with
instrumentation no one has.
I fully accept your standing wave current measurements, Tom, but standing
wave current measurements will not yield the information that we are after.
We need to know the phase shift in the forward and reflected currents
through the coil. Standing wave measurements simply will not yield that
information. Self-resonance measurements will yield that information.
The delay through a coil that is self-resonant on 16 MHz is 15.6 nS.
--
73, Cecil
http://www.qsl.net/w5dxp