Cecil Moore wrote:
Gene Fuller wrote:
I believe you said you saw about a 7% shift between the two inputs to
your scope.

I don't recall saying anything like that. I don't even
know what that means. 7% of what?

Cecil,

Sorry, English is not my native language this month. I must have
misinterpreted the following message sent by you (11/30/2007, 3:35 pm).

****************

Jim Kelley wrote:
Cecil Moore wrote:

I measured a ~25 nS delay in a 75m bugcatcher coil.

What did you use to make that measurement? (I hope you don't say you
used a Bird Wattmeter.)

I've described it before. I used a dual-trace
100 MHz O-scope and estimated the phase angle
between the two traces at about 7% of a cycle.
That phase angle was certainly NOT ANYWHERE
NEAR the 4.5 degrees reported by W8JI.

W8JI measured a 4.5 degree phase shift in the
standing-wave current being used for the
measurement although virtually no phase
information exists in the standing-wave current
phase. W7EL made exactly the same mistake in
his measurements. No wonder the two agree.
--
73, Cecil http://www.w5dxp.com


****************

73,
Gene
W4SZ

Cecil Moore wrote:

I've described it before. I used a dual-trace
100 MHz O-scope and estimated the phase angle
between the two traces at about 7% of a cycle.
That phase angle was certainly NOT ANYWHERE
NEAR the 4.5 degrees reported by W8JI.

W8JI measured a 4.5 degree phase shift in the
standing-wave current being used for the
measurement although virtually no phase
information exists in the standing-wave current
phase. W7EL made exactly the same mistake in
his measurements. No wonder the two agree.

*Chuckle* I made the "mistake" of measuring current, the definition of
which can be found in any elementary electrical circuits text. Contrary
to Cecil's objections, phase is a property of periodic steady state
current (as can also be discovered from reading a basic text), and
certainly can be measured. I measured it and so did Tom, but Cecil sure
doesn't seem to like the results. Cecil's and his scope are apparently
able to measure something else -- whatever it is, I'm afraid my scope
doesn't have the magical properties needed to measure it.

I did, however, do at least a couple of things which Cecil might have
overlooked. One is that I was careful to terminate each of the current
probes with a low-resistance low-reactance load to reduce the insertion
impedance to a very low value. Another is that I put both probes on the
same wire to verify that their outputs were in phase. These steps alone
might have broken the magic spell necessary to measure whatever
different kinds of current Cecil imagines.

Can anyone point me to any reference to "standing-wave current" in any
reputable text? As far as I can tell, it's something Cecil made up to
mean whatever is necessary at the moment to discount others'
measurements. It seems to be working quite well -- in the endless
discussions, he's trotted it out many times without anyone to my
recollection even asking him what it is and how it differs from the
current described in textbooks (you know, the rate of charge flow?). Or
why "virtually no phase information" exists in it. A periodic waveform
with no phase information? Huh?

There's no mystery about traveling or standing waves -- both are very
well understood, mathematically rigorous, and have been used for over a
century with great success in the design of countless real things that
work. But muddled "standing wave currents" and bouncing waves of average
power, supported only by hand waving and misdirection, don't bear much
resemblance to the highly developed, rigorous, and self-consistent body
of knowledge that's served us so well for so long.

But each to his own.

Roy Lewallen, W7EL

Roy Lewallen wrote:

Please fire up EZNEC and tell us how much current phase
shift is reported for 45 degrees of a 1/2WL dipole.

Can anyone point me to any reference to "standing-wave current" in any
reputable text?

"Transmission Lines", by Chipman, Chapter 8

A periodic waveform with no phase information? Huh?

Yes!!! Here's what Chipman says on page 159: "V(d)=A*cos(Bd).
This expression indicates that in the voltage standing wave
pattern produced on a lossless transmission line by a voltage
reflection coefficient, rho, at the terminal load end, the
*phase is constant over any half wavelength* of the pattern
between successive points of zero voltage magnitude, ..."

The same is true for the current standing wave pattern on
a standing-wave antenna and means that constant phase current
cannot be used for delay measurements.

"PHASE IS CONSTANT OVER ANY HALF WAVELENGTH" including the
part where the coil is located.

Please look at the phase of the current in a 1/2WL dipole
and tell us how to use phase measurements of that current
to determine the delay through the 1/2WL dipole wire.

There's no mystery about traveling or standing waves ...

Roy, please explain the phase shift reported by EZNEC for:

http://www.w5dxp.com/coil512.ez

Use the "Load Dat" button to view the phase shift.
--
73, Cecil http://www.w5dxp.com

Roy Lewallen wrote:
Can anyone point me to any reference to "standing-wave current" in any
reputable text?

Will Kraus do? Here's a graphic from his book, "Antennas".
Please look at the phase of the current over the entire
1/2WL dipole. EZNEC and Chipman agree with Kraus.

http://www.w5dxp.com/krausdip.jpg
--
73, Cecil http://www.w5dxp.com

Gene Fuller wrote:
Cecil Moore wrote:
Gene Fuller wrote:
I believe you said you saw about a 7% shift between the two inputs to
your scope.

I don't recall saying anything like that. I don't even
know what that means. 7% of what?

Sorry, English is not my native language this month. I must have
misinterpreted the following message sent by you (11/30/2007, 3:35 pm).

I've described it before. I used a dual-trace
100 MHz O-scope and estimated the phase angle
between the two traces at about 7% of a cycle.

Sorry, I obviously made an error. It should have
been about 10% of a cycle.
--
73, Cecil http://www.w5dxp.com