The point I was trying to make on the "Rotational Speed"
thread got lost in semantics so here goes again.

Given - a 75m dipole modeled by EZNEC with 90 segments
in each leg of the dipole. 90 segments was chosen
to correspond to the number of degrees from the
feedpoint. Illustrating 1/2 of the dipole with
0 ohm loads at the following segments:

FP--------23--------46--------68--------90

EZNEC reports the following results:

Feedpoint current: 1 amp at 0 deg

Current at seg 23: 0.9281 amp at -1.06 deg

Current at seg 46: 0.7154 amp at -1.78 deg

Current at seg 68: 0.4049 amp at -2.31 deg

Current at seg 90: 0.0122 amp at -2.76 deg

Since the segment numbers correspond to the
number of degrees, it's obvious that the
segment numbers correspond to the expected
phase shift in the traveling waves.

Question: Assuming the current reported by
EZNEC is a ~cosine function, how does one use
that current to determine the traveling wave
phase shift in the wire?
--
73, Cecil http://www.w5dxp.com

"Cecil Moore" wrote in message
...
The point I was trying to make on the "Rotational Speed"
thread got lost in semantics so here goes again.

Given - a 75m dipole modeled by EZNEC with 90 segments
in each leg of the dipole. 90 segments was chosen
to correspond to the number of degrees from the
feedpoint. Illustrating 1/2 of the dipole with
0 ohm loads at the following segments:

FP--------23--------46--------68--------90

EZNEC reports the following results:

Feedpoint current: 1 amp at 0 deg

Current at seg 23: 0.9281 amp at -1.06 deg

Current at seg 46: 0.7154 amp at -1.78 deg

Current at seg 68: 0.4049 amp at -2.31 deg

Current at seg 90: 0.0122 amp at -2.76 deg

Since the segment numbers correspond to the
number of degrees, it's obvious that the
segment numbers correspond to the expected
phase shift in the traveling waves.

Question: Assuming the current reported by
EZNEC is a ~cosine function, how does one use
that current to determine the traveling wave
phase shift in the wire?
--
73, Cecil http://www.w5dxp.com

What is the current phase relative to. The feedpoint , the voltage in that
segment? As I have read this thread there seems to be some confusion on
this point.

Jimmie D wrote:
"Cecil Moore" wrote in message
...
The point I was trying to make on the "Rotational Speed"
thread got lost in semantics so here goes again.

Given - a 75m dipole modeled by EZNEC with 90 segments
in each leg of the dipole. 90 segments was chosen
to correspond to the number of degrees from the
feedpoint. Illustrating 1/2 of the dipole with
0 ohm loads at the following segments:

FP--------23--------46--------68--------90

EZNEC reports the following results:

Feedpoint current: 1 amp at 0 deg

Current at seg 23: 0.9281 amp at -1.06 deg

Current at seg 46: 0.7154 amp at -1.78 deg

Current at seg 68: 0.4049 amp at -2.31 deg

Current at seg 90: 0.0122 amp at -2.76 deg

Since the segment numbers correspond to the
number of degrees, it's obvious that the
segment numbers correspond to the expected
phase shift in the traveling waves.

Question: Assuming the current reported by
EZNEC is a ~cosine function, how does one use
that current to determine the traveling wave
phase shift in the wire?

What is the current phase relative to. The feedpoint , the voltage in that
segment? As I have read this thread there seems to be some confusion on
this point.

I believe that EZNEC references net current to the
source current of 1A at 0 degrees. I consider it
to be a *snapshot* of conditions when the source
current is 1A at 0 degrees. This is what I have
been assuming in all of my postings. I believe
that is also what Kraus does in his graphs.
--
73, Cecil http://www.w5dxp.com

On Apr 28, 9:36 am, Cecil Moore wrote:
Question: Assuming the current reported by
EZNEC is a ~cosine function, how does one use
that current to determine the traveling wave
phase shift in the wire?

Why is the answer to this question important?
Is it not the actual currents and voltages that are responsible
for radiation?

If I understand correctly, you are not disputing that the
actual currents in the wire show a small phase shift as
you move down the wire?

....Keith

Keith Dysart wrote:
On Apr 28, 9:36 am, Cecil Moore wrote:
Question: Assuming the current reported by
EZNEC is a ~cosine function, how does one use
that current to determine the traveling wave
phase shift in the wire?

Why is the answer to this question important?

Because it holds the key to determining the phase delay
through a 75m mobile loading coil.
--
73, Cecil http://www.w5dxp.com

Cecil Moore wrote:
The point I was trying to make on the "Rotational Speed"
thread got lost in semantics so here goes again.

Given - a 75m dipole modeled by EZNEC with 90 segments
in each leg of the dipole. 90 segments was chosen
to correspond to the number of degrees from the
feedpoint. Illustrating 1/2 of the dipole with
0 ohm loads at the following segments:

FP--------23--------46--------68--------90

EZNEC reports the following results:

Feedpoint current: 1 amp at 0 deg

Current at seg 23: 0.9281 amp at -1.06 deg

Current at seg 46: 0.7154 amp at -1.78 deg

Current at seg 68: 0.4049 amp at -2.31 deg

Current at seg 90: 0.0122 amp at -2.76 deg

Since the segment numbers correspond to the
number of degrees, it's obvious that the
segment numbers correspond to the expected
phase shift in the traveling waves.

Question: Assuming the current reported by
EZNEC is a ~cosine function, how does one use
that current to determine the traveling wave
phase shift in the wire?

Cecil,

So soon we forget. In a standing wave antenna the phase is gone, kaput.
I believe you have even quoted me on occasion when it was convenient for
the purpose you had at the moment.

Since the traveling wave phase exists only in your imagination, just
pick a number that supports whatever you are trying to "prove" now.


73,
Gene
W4SZ

Gene Fuller wrote:
So soon we forget. In a standing wave antenna the phase is gone, kaput.
I believe you have even quoted me on occasion when it was convenient for
the purpose you had at the moment.

And it is again convenient to quote you:

The only "phase" remaining is the cos (kz) term, which is really
an amplitude description, not a phase.

You also have said that all the phase information is still there,
that superposition doesn't destroy any information. I believe you.
The standing wave current is a cosine function. The arc-cosine of
the amplitude yields the phase of the component waves.

Since the traveling wave phase exists only in your imagination, just
pick a number that supports whatever you are trying to "prove" now.

The point is that this is the very current that Roy used to
"measure" the phase shift through a loading coil. I agree with
you that standing wave current cannot be used to measure the
phase shift through a loading coil. Now if you will tell that
technical fact to Roy, he can withdraw his previous assertions.

It seems that you are contradicting yourself by saying that all
the information in the component waves is still there after
superposition yet you say the phase is gone. Both statements
cannot be true.
--
73, Cecil http://www.w5dxp.com

Cecil Moore wrote:


It seems that you are contradicting yourself by saying that all
the information in the component waves is still there after
superposition yet you say the phase is gone. Both statements
cannot be true.

Cecil,

Both statements are true. Superposition does not favor one description
over the other. If there is no phase information remaining in the
superposed result (the standing wave) then there is no phase information
remaining at all, regardless of your mathematical manipulations. There
are no hidden variables.

Someone else recently pointed out that Mother Nature does not care what
models we use; the underlying physical reality will be the same. You
continue to try to get around that fundamental principle, but it won't work.

73,
Gene
W4SZ

Gene Fuller wrote:
Cecil Moore wrote:
It seems that you are contradicting yourself by saying that all
the information in the component waves is still there after
superposition yet you say the phase is gone. Both statements
cannot be true.

Both statements are true. Superposition does not favor one description
over the other. If there is no phase information remaining in the
superposed result (the standing wave) then there is no phase information
remaining at all, regardless of your mathematical manipulations. There
are no hidden variables.

But you said (and for some unknown reason trimmed):

The only "phase" remaining is the cos (kz) term, which is really
an amplitude description, not a phase.

I agree with you. The phase of the underlying forward and
reflected traveling waves can be deduced from the *amplitude*
of the standing wave. Here is a graphic excerpted from the
recently available PDF 1st edition of "Antennas" by Kraus.
EZNEC can also be used with the same results.

http://www.w5dxp.com/krausdip.jpg

As you can see, the current amplitude is a ~cosine function.
The phase of the forward traveling wave relative to a source
wave of 1.0 amp at 0 degrees (EZNEC standard) is an ARC-COSINE
function of the current amplitude. For instance, at 45 degrees
away from the feedpoint, the current is ~0.707 amps. ARC-COSINE
of 0.707 is 45 degrees. You were correct when you said that
the information in the forward and reflected waves is preserved
in the standing waves. Kraus' graphic proves it.

But it has yet to be explained how Roy (and Tom R.) could
use the essentially unchanging *phase* of the standing wave
current to "measure" the phase shift through a loading coil
- since the phase of the standing wave current cannot even
be used to determine the phase shift through a wire. This
question has been asked many times. The absence of an answer
stands out like a sore thumb.

Roy said:
What I measured was a 3.1% reduction in magnitude from input to output,
with no discernible phase shift.

Of course there was no discernible phase shift as can be seen from
Kraus' graphic above. But Kraus' graph gives us a way to deduce
the phase shift from the amplitudes. Assuming a reference amplitude
of 1.0 amp at the bottom of the coil, a 3.1% reduction would give
us 0.969 amps at the top of the coil. ARC-COSINE(0.969) = 14.3 deg.
That's a close approximation of the phase shift through the coil
being undergone by the forward current and reflected current.

If the forward current at the bottom of the coil is 0.55A @ 0 deg,
and the reflected current at the bottom of the coil is
0.45A @ 0 deg, the total current at the bottom of the coil
is 1.0A @ 0 deg. With a 14.3 degree phase shift through the
coil, the forward current at the top of the coil would be
0.55A @ -14.3 deg and the reflected current would be
0.45A @ +14.3 deg. Adding those two phasors together yields

0.55A*cos(-14.3) + 0.45A*cos(+ 14.3) = 0.533A + 0.436A = 0.969A
at the top of the coil. 0.969A is 3.1% lower than the 1.0 amp
at the bottom of the coil. Everything is perfectly consistent
with a 14.3 degree phase shift through the coil for the two
traveling waves.
--
73, Cecil http://www.w5dxp.com

Cecil Moore wrote:

But it has yet to be explained how Roy (and Tom R.)

Cecil,

I don't post under an alias. My name is neither Tom nor Roy. I have
never attempted to measure the phase shift in a loading coil.

See you the next time you try to practice physics without a license.

8-)

73,
Gene
W4SZ