wrote:
I assume, then, that from now on you will constrain the use
rho=Sqrt(Pref/Pfwd) to situations where Pref is zero?

No, the equation from Ramo & Whinnery from which the above
is developed is

Pz-/Pz+ = |rho|^2 and take the square root of each side.

Like I said at first, I made a boo-boo and should have put absolute
value signs around 'rho'. You are completely ignoring that response
of mine.

My gosh, you work hard to find disagreement. In my sentence above,
please update "there are NET reflections" with "there may be NET
reflections".

Shirley, you can understand that the first statement is an absolute-
exclusive and the second statement is a conditional-inclusive and
are logically opposite statements, one false and the other true.

If readers spent just a small fraction of their effort interpreting
for agreement instead, discussion would flow so much more smoothly.

Interpreting an exclusive statement as an inclusive statement is
logically invalid.

Sometimes, there are net reflections existing where there is no
impedance discontinuity.

Excellent. Agreement.

Nope, not agreement. Your absolute statement was false. My conditional
statement is true. If you had said 'sometimes', your statement would have
been true instead of false. You made a logical error. It's no biggie.
I left off the absolute magnitude signs. It's no biggie.
--
73, Cecil http://www.qsl.net/w5dxp



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Dr. Slick wrote:

Cecil Moore wrote:
Pz-/Pz+ = |rho|^2 and take the square root of each side.

And this shows us that if [rho] is greater than one, the reflected
power will be greater than the incident power.

Maybe, or maybe the equation assumes Z0 is not complex. I don't know
the assumptions. Which leads to another question. Can the index of
refraction for a material be complex? To the best of my knowledge,
there's no mention of complex indices of refraction in _Optics_.

... most of the literature has rho=[gamma].
Where gamma is the complex reflection coefficient, and rho is only the
magnitude.

That is the convention I use. Unfortunately, it is not universal and may
even be old-fashioned, like me. :-)
--
73, Cecil http://www.qsl.net/w5dxp



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Cecil Moore wrote:

wrote:
My gosh, you work hard to find disagreement. In my sentence above,
please update "there are NET reflections" with "there may be NET
reflections".

Shirley, you can understand that the first statement is an absolute-
exclusive and the second statement is a conditional-inclusive and
are logically opposite statements, one false and the other true.

That is the beauty of reading for disagreement; you can always
justify the disagreement.

If readers spent just a small fraction of their effort interpreting
for agreement instead, discussion would flow so much more smoothly.

Interpreting an exclusive statement as an inclusive statement is
logically invalid.

To read for agreement, the reader examines statements in context
and ignores the minor inconsistencies that the author has made in
the prose. Taking each statement out of context and examining it
individually will provide a myriad of opportunities for finding
disagreement, if that is the objective.

Sometimes, there are net reflections existing where there is no
impedance discontinuity.

Excellent. Agreement.

Nope, not agreement. Your absolute statement was false. My conditional
statement is true.

There it is again; searching for disagreement.

If you had said 'sometimes', your statement would have
been true instead of false.

And is that not exactly what I did with my clarification to
the original sentence?

Are you sure that you do not read with the intent of maximizing
disagreement?

....Keith

wrote:
And is that not exactly what I did with my clarification to
the original sentence?

Thanks for correcting your error.
--
73, Cecil http://www.qsl.net/w5dxp



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Keith wrote:
"---it is this cyclical variation in energy flow which prompted power
dudes to invent three phase lines in which energy flow does not vary
cycillaly, power is constant."

It`s true the wires are shared by multiple phases which peak 120-degrees
apart in the 3-phase case. This distributes power flow more evenly with
respect to time and reduces peak loads since the phases never coicide.
Tesla figured this out 100 years ago.

Coincidences of incident and reflected waves are very different from the
cyclical variations of a-c.

Incident and reflected waves have cyclical voltages and currents. As the
reflected wave is just a delayed incident wave, the period is the same
for both.

In those line spots where the total reflected voltage is 180-degrees
different in phase from the incident wave, the net voltage is always
zero during the cycle if the reflection is complete on a lossless line.

The power is not zero at points where the voltage is always zero because
the voltages that add to zero are not zero. In the lossless line, these
voltages are full strength, as are the currents at a current null, some
90-degrees away in space from the voltage null on the line.

Fact is, both the forward power and the reflected power would measure
the same at any point along the line.

The wave action has been observed and documented for more than a
century. The explanations withstand all arguments, so far. Something new
will be needed to replace the ancient wave theory to win acceptance.
Keith`s zero power at zero null spots won`t persuade.

The power appearing to null is not the whole story when there are
forward and reflected powers, each having electric and magnetic fields
with phase differences all around.

Best regards, Richard Harrison, KB5WZI

W5DXP wrote:

wrote:

W5DXP wrote:

Jim Kelley wrote:
Nodes and zero crossings aren't necessarily the same thing.

They are for standing waves on lossless unterminated lines,
by definition.

Zero crossings are not unique to standing wave patterns, therefore nodes
and zero crossing aren't necessarily the same thing.

What are you claiming crosses zero at a node in a standing wave pattern?

73 de ac6xg

Cecil Moore wrote:
To the best of my knowledge,
there's no mention of complex indices of refraction in _Optics_.

Born and Wolf has a chapter on the Optics of Metals. Chapter 13.1 is
called Wave Propagation in a Conductor. In it, they use a complex wave
number, complex dielectric constant, complex phase veloctity, and a
complex refractive index.

73, Jim AC6XG

Jim Kelley wrote:
Zero crossings are not unique to standing wave patterns,
therefore nodes and zero crossing aren't necessarily the same thing.

A zero crossing exists at a node in a lossless unterminated
transmission line. If they were the same thing there wouldn't
need to be two different names, would there?
--
73, Cecil http://www.qsl.net/w5dxp



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Jim Kelley wrote:

Cecil Moore wrote:
To the best of my knowledge,
there's no mention of complex indices of refraction in _Optics_.

Born and Wolf has a chapter on the Optics of Metals. Chapter 13.1 is
called Wave Propagation in a Conductor. In it, they use a complex wave
number, complex dielectric constant, complex phase veloctity, and a
complex refractive index.

Yep, also found it in _Optics_ under "Waves in a Metal".
--
73, Cecil http://www.qsl.net/w5dxp



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