Cecil,

I am not Tom, but I will respond anyhow.

It is so hard to keep up with you. This entire thread started a few days ago
with a debate between you and Roy. You chastised Roy for considering the net
current instead of the individual components. Now you have switched back to
talking about net currents resulting from the addition of individual phasor
currents.

Which one do you want to talk about?

It is unlikely that anyone reading this newsgroup is confused regarding the back
and forth nature of the current on a thin wire. To insinuate such is merely a
cheap shot that appears intended to intimidate. (Go ahead, take your best shot.)
8-)

The concept of phasors is a common and useful tool for visualization and some
elementary numerical solutions. The simple standing wave analysis currently
under discussion and debate is certainly an appropriate subject for phasor
treatment. However, once outside of the realm of ideal one-dimensional systems
the use of phasors gets much more complicated. The use of conventional
mathematics for such problems is pretty standard.

The typical equation describing a standing wave is:

I = A * sin (kx) sin (wt)

The spatial phase of this equation is "kx", while the temporal phase is "wt". At
no time do these phases suddenly reverse direction. The resulting value for I
ranges through positive and negative values, and again it is unlikely that
anyone is confused.

If you choose to call the switch from current flow in the positive direction to
the negative direction a 180 degree phase shift, so be it. I prefer to keep the
phase in its place and let the sine function do its thing to reverse the value
of the equation.

73,
Gene
W4SZ


Cecil Moore wrote:

Tdonaly wrote:

(P.S. Art, I hope you don't equate disagreement with ridicule. I
reserve all my
ridicule for Cecil since he can take it.)


.... .. .... ..

Tom, I notice you have not posted your calculations for
the phase angles of those superposed phasors I presented
yesterday. Did you come up with any phase angle other
than zero and 180 degrees? Do you understand why Kraus'
phase graph for standing wave current contains only two
possible values of phase?
--
73, Cecil, W5DXP

Gene Fuller wrote:
It is so hard to keep up with you. This entire thread started a few days
ago with a debate between you and Roy. You chastised Roy for considering
the net current instead of the individual components. Now you have
switched back to talking about net currents resulting from the addition
of individual phasor currents.

Which one do you want to talk about?

Nice try, Gene. What got Roy into trouble is forgetting that the net
current consists of two components. One can choose to talk about either
the components or the net as long as one realizes that the net is the
sum of the components. Roy has said, in so many words, that I am stupid
to worry about the components when all I need to worry about is the net.
It's obvious that Kraus worries about the components and, therefore, I
have good reason for such. Great insight is afforded to he who considers
the primary components of the sum instead of ignoring them.

At no time do these phases suddenly reverse direction.

Aha, so you disagree with Kraus and apparently don't understand the
thin wire analysis of standing waves in his book.

If you choose to call the switch from current flow in the positive
direction to the negative direction a 180 degree phase shift, so be it.

A DDS chip can generate a sine wave. Are you telling me that +0.001 volts
out of a DDS chip is not 180 degrees different from a -0.001 volts out of
a DDS chip? At exactly what voltage level does it have to get to to call
it a 180 degree phase shift? If all you see is a step from +0.001 volts
to -0.001 volts, does the information that you don't know dictate whether
is is a 180 degree phase shift or some other phase shift? If so, you are
in deep doo-doo, my friend, and you cannot trust any measurements because
there are always unknowns.

This situation of math models dictating reality (instead of vice-versa) is
worse than I thought. In reality, there is no imaginary current when the
real current is zero. All current in the real-world is real. I suppose that
all current in the imaginary world is imaginary but that's not the world I
live in. If the real current is zero then, for people living in the real world,
the current is zero - there ain't no more. In reality, God doesn't control
everything about the universe according to his whim. HE allows HIS physical
laws to run the universe. If a 180 degree reversal in the direction of flow
of current is not a 180 degree reverse in reality, exactly what is it? If you
have a square wave with one amp as the maximum, and -0.1 amp as the minimum,
is that not a 180 degree phase shift? If you have a square wave with 0.00001
amp as the maximum and 0.00001 amp as the minimum is that not a 180 degree
phase shift? Is the quantum shift from +0.0000...01 volts to -0.0000...01
volts not a shift of 180 degrees?

Gene, I hate to burst your (sacred cow) bubble, but the imaginary part of
the current doesn't actually exist in my universe. If it exists in yours,
I suggest you subscribe to r.r.a.a in that universe, wherever it might be.
--
73, Cecil http://www.qsl.net/w5dxp



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Cecil,

What in the world are you blathering on about?

(That's a rhetorical question. No answer needed.)

I stated my position, and I have nothing more to add. Feel free to continue to
amuse yourself.

73,
Gene
W4SZ

Cecil Moore wrote:
Gene Fuller wrote:

It is so hard to keep up with you. This entire thread started a few
days ago with a debate between you and Roy. You chastised Roy for
considering the net current instead of the individual components. Now
you have switched back to talking about net currents resulting from
the addition of individual phasor currents.

Which one do you want to talk about?


Nice try, Gene. What got Roy into trouble is forgetting that the net
current consists of two components. One can choose to talk about either
the components or the net as long as one realizes that the net is the
sum of the components. Roy has said, in so many words, that I am stupid
to worry about the components when all I need to worry about is the net.
It's obvious that Kraus worries about the components and, therefore, I
have good reason for such. Great insight is afforded to he who considers
the primary components of the sum instead of ignoring them.

At no time do these phases suddenly reverse direction.


Aha, so you disagree with Kraus and apparently don't understand the
thin wire analysis of standing waves in his book.

If you choose to call the switch from current flow in the positive
direction to the negative direction a 180 degree phase shift, so be it.


A DDS chip can generate a sine wave. Are you telling me that +0.001 volts
out of a DDS chip is not 180 degrees different from a -0.001 volts out of
a DDS chip? At exactly what voltage level does it have to get to to call
it a 180 degree phase shift? If all you see is a step from +0.001 volts
to -0.001 volts, does the information that you don't know dictate whether
is is a 180 degree phase shift or some other phase shift? If so, you are
in deep doo-doo, my friend, and you cannot trust any measurements because
there are always unknowns.

This situation of math models dictating reality (instead of vice-versa) is
worse than I thought. In reality, there is no imaginary current when the
real current is zero. All current in the real-world is real. I suppose that
all current in the imaginary world is imaginary but that's not the world I
live in. If the real current is zero then, for people living in the real
world,
the current is zero - there ain't no more. In reality, God doesn't control
everything about the universe according to his whim. HE allows HIS physical
laws to run the universe. If a 180 degree reversal in the direction of flow
of current is not a 180 degree reverse in reality, exactly what is it?
If you
have a square wave with one amp as the maximum, and -0.1 amp as the
minimum,
is that not a 180 degree phase shift? If you have a square wave with
0.00001
amp as the maximum and 0.00001 amp as the minimum is that not a 180 degree
phase shift? Is the quantum shift from +0.0000...01 volts to -0.0000...01
volts not a shift of 180 degrees?

Gene, I hate to burst your (sacred cow) bubble, but the imaginary part of
the current doesn't actually exist in my universe. If it exists in yours,
I suggest you subscribe to r.r.a.a in that universe, wherever it might be.

Cecil, W5DXP wrote:
"If a 180 degree reversal in the direction of flow of current ia not a
180 degree reversal in reality, exactly what is it?"

From the 1937 second edition of Terman`s "Radio Engineering" page 70:

"In the case of both open- and short-circuited receivers (transmission
line loads) the voltage and current are substantially 90-degrees out of
phase at all places along the line except in the vicinity of the
quarter-wave-length points where the phase angle rapidly shifts from
nearly 90-degrees on one side of unity power factor to nearly 90-degrees
on the other side of unity power factor. The voltages on opposite sides
of a voltage minimum are therefore substantially 180-degrees out of
phase, as are also the currents on opposite sides of a current minimum.
In order to show this change of phase, the voltage and current
distributions in circuits with distributed constants are frequently
drawn as shown in Fig. 34---."

It helps to have Terman`s Figs. 33 and 34 in front of you to be
persuaded of the abrupt phase transistions. Terman can be accepted on
faith and his truth eventually sinks in.

Best regards, Richard Harrison, KB5WZI

My understanding is that the phase of the forward and reflected waves
varies along the transmission line. One 'rotates clockwise' the other
'rotates counterclockwise'. In the case of 'perfect reflection', a
mathematical study condition, the sum of these two waves varies along
the transmission line. The resultant sum produces the minimum and
maximum voltage we observe in a slotted line. It is to be noted that the
phase shifts at the all half wave points from the load, by convention,
rotate from the 'positive' two quadrants to the negative two quadrants.
Therefore, a polarity change exists.

Is this the 180 degree phase shift being discussed?

Deacon Dave, W1MCE
+ + +

SNIP

At no time do these phases suddenly reverse direction.


Aha, so you disagree with Kraus and apparently don't understand the
thin wire analysis of standing waves in his book.

If you choose to call the switch from current flow in the positive
direction to the negative direction a 180 degree phase shift, so be it.


SNIP

Dave Shrader wrote:
My understanding is that the phase of the forward and reflected waves
varies along the transmission line. One 'rotates clockwise' the other
'rotates counterclockwise'. In the case of 'perfect reflection', a
mathematical study condition, the sum of these two waves varies along
the transmission line. The resultant sum produces the minimum and
maximum voltage we observe in a slotted line. It is to be noted that the
phase shifts at the all half wave points from the load, by convention,
rotate from the 'positive' two quadrants to the negative two quadrants.
Therefore, a polarity change exists.

If a current is 0 + j1.0 amps, exactly where is that one amp of current
located? The real component of phasor current always lies along the 'x'
real axis. A change from +0.001 amp at zero degrees through a zero magnitude
to -0.001 amp at 180 degrees is a 180 degree phase shift in *real* current
that exists in the real world. Imaginary current is, well, imaginary, and
is an artifact of the phasor math model. Has anyone ever measured j1.0 amps
of current at a point where the real current is zero?

Is this the 180 degree phase shift being discussed?

Originally, the 180 degrees phase shift being discussed was concerning
a current standing wave in a thin wire where the forward current and
reflected current are equal in magnitude. The phase of the net current
is 0 degrees for awhile and then shifts abruptly to 180 degrees according
to Kraus.

There are only two directions in a wire. For an AC signal, the current
is flowing one direction for 1/2 cycle and the other direction for the
other 1/2 cycle. The *real* magnitude of the current varies with physical
length (sin kL) and can be analyzed without any reference to phase.
--
73, Cecil http://www.qsl.net/w5dxp



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