Roger Sparks wrote:
You need to take a look at the spreadsheets.

Roger, in a nutshell, what is the bottom line?
--
73, Cecil http://www.w5dxp.com

Cecil Moore wrote:
Roger Sparks wrote:
You need to take a look at the spreadsheets.

Roger, in a nutshell, what is the bottom line?

The bottom line in a nutshell? I'll try.

First, I added a note to both spreadsheets indicating that zero degrees
is CURRENT zero degrees. This because the source turns out to be
reactive, with current peak 45 degrees from voltage peak.

http://www.fairpoint.net/~rsparks/Sm...Reflection.pdf

The spreadsheet addresses the following issues:

Does the traveling wave carry power? Yes. The spreadsheet was built
assuming that power is carried by traveling waves. Because the
resulting wave form and powers seem correct, the underlaying assumption
seems correct.

Is power conserved on the transmission line, meaning, can the energy
contained in power be conserved and located over time on the
transmission line? Yes, the spreadsheet was built assuming that power
could be conserved and traced over time so the underlaying assumption
seems correct.

Does interference occur in this example? The spreadsheet was built
assuming that voltage and currents from superpose in a manner consistent
with constructive and destructive interference, so the underlaying
assumption seems correct.

Is power stored in the reactive component for release in later in the
cycle or during the next half cycle? Yes, power is stored on the
transmission line during the time it takes for power to enter the line,
travel to the end and return. The time of wave travel on the
transmission line is related to the value of the reactive component.

Does the direction of wave travel affect the measurement of voltage and
the application of power to a device? Yes. A wave loses energy (and
therefore voltage) as it travels through a resistance. As a result,
power from the prime source is ALWAYS applied across the sum of the
resistance from the resistor AND transmission line. The spreadsheet was
built using this assumption and seems correct. (At times during the
cycle, the forward and reflected waves oppose, resulting in very little
current through the resistor. During those times, the power applied to
the transmission line is much HIGHER because the reflected wave reflects
from the load and source, and merges/adds to the forward wave from the
source.)

Is the power interference equation Ptot = P1 + P2 +
2*SQRT(P1*P2)cos(theta) valid? The equation was not reviewed on this
spreadsheet.

The bottom line, but maybe not in a nutshell.

73, Roger, W7WKB

Roger Sparks wrote:
The bottom line in a nutshell? I'll try.

Thanks Roger, good stuff and much appreciated.
My digesting of your spread sheets is about to
be interrupted by surgery.

During those times, the power applied to
the transmission line is much HIGHER because the reflected wave reflects
from the load and source, and merges/adds to the forward wave from the
source.)

May I suggest that you use the word "redistributed"
instead of "reflected" as does the FSU web page at:

http://micro.magnet.fsu.edu/primer/j...ons/index.html

For the purposes of this discussion, I would suggest
that the word "reflection" be reserved for something
that happens to a single wave. When two waves are
superposed, energy can be redistributed but technically
it is not an ordinary reflection. I once used the
word "reflection" to describe both phenomena and it
confused people. Now I am careful to call the
reversal of energy flow due to superposition a
"redistribution" instead of a "reflection".

For instance, the multi-colored patterns seen when
a thin film of oil is on top of a puddle of water
is not an ordinary reflection but a combination
of multiple reflections and interference.

In addition, the reflection coefficient seen by the
reflected wave in our examples is 0.0 since the source
impedance equals the characteristic impedance of the
transmission line. There are no ordinary reflections
when the reflection coefficient is zero.
--
73, Cecil http://www.w5dxp.com

On Thu, 27 Mar 2008 11:49:03 GMT
Cecil Moore wrote:

Roger Sparks wrote:
The bottom line in a nutshell? I'll try.

Thanks Roger, good stuff and much appreciated.
My digesting of your spread sheets is about to
be interrupted by surgery.

Thanks for the kind words. Sorry to hear about your surgery. I hope it goes well and you have a quick recovery.

During those times, the power applied to
the transmission line is much HIGHER because the reflected wave reflects
from the load and source, and merges/adds to the forward wave from the
source.)

May I suggest that you use the word "redistributed"
instead of "reflected" as does the FSU web page at:

http://micro.magnet.fsu.edu/primer/j...ons/index.html

Clip

I think "redistributed" would be the word if the discontinuity included a resistance. "Reflection" is the historical word for wave reversal and implies a "mirror image", which is not the same as the forward image.

I hope the surgery does not take you away from the discussion for long.

--
73, Roger, W7WKB

Roger Sparks wrote:
I think "redistributed" would be the word if the discontinuity
included a resistance. "Reflection" is the historical word for
wave reversal and implies a "mirror image", which is not the same
as the forward image.

What I am suggesting is that "redistribution" be used
instead of "reflection" for cases where there exists
no discontinuity. If the source resistor matches the
Z0 of the feedline, there is no discontinuity and
therefore no conventional reflection, yet there are
cases where reflected energy is redistributed back
toward the load. That reversal appears to be a reflection
but is actually the result of superposition along
with destructive interference between *two* waves.
That is what causes the disparity between the physical
reflection coefficient, (Z1-Z2)/(Z1+Z2), and the virtual
reflection coefficient, SQRT(Pref/Pfor).

I hope the surgery does not take you away from the discussion
for long.

At the least, I should still have one good eye left. ;-)
--
73, Cecil http://www.w5dxp.com

Cecil Moore wrote:


What I am suggesting is that "redistribution" be used
instead of "reflection" for cases where there exists
no discontinuity.

This is sad.

But I suppose that if you are going to invent new science you might as
well invent new terminology as well. 8-)

Yes, I know that the now-famous FSU web page uses "redistribution". Did
you happen to notice that the page was created by a lab tech and a Java
programmer? Do you suppose Hecht, Born and Wolf, and all of the other
acknowledged experts would support dumping "reflection"?

73,
Gene
W4SZ

Gene Fuller wrote:
Yes, I know that the now-famous FSU web page uses "redistribution".
Do you suppose Hecht, Born and Wolf, and all of the other
acknowledged experts would support dumping "reflection"?

I would guess the answer is "yes" when the physical
reflection coefficient is zero - in order to avoid
a logical contradiction.

How does a "reflection" occur when the physical reflection
coefficient is zero, in violation of the wave reflection
model? Why is there often a difference between the
physical reflection coefficient and the virtual
reflection coefficient? Which one is wrong?

The convention that I have adopted is that the word
"reflection" is reserved for single wave events.

For multiple wave events where interference exists,
something besides a simple "reflection" takes place.
The intricate color patterns on the surface of a thin
film of oil floating on a puddle of water are not
simple reflections but instead an interaction of
multiple reflected waves. The resulting image bears
absolutely no resemblance to the incident image.

Following the FSU web page usage, the word "redistribution"
is used for multiple wave interaction events like wave
cancellation. (The words we choose to use to describe the
phenomena have zero effect on the phenomena.)

"A rose by any other name would smell as sweet."
--
73, Cecil http://www.w5dxp.com

Gene Fuller wrote:
Did you happen to notice that the page was
created by a lab tech and a Java programmer?

Gene, if a tech asserts a fact and an expert
asserts a falsehood, who are you going to
choose to believe?
--
73, Cecil http://www.w5dxp.com

On Mar 27, 2:06 am, Roger Sparks wrote:
Cecil Moore wrote:
Roger Sparks wrote:
You need to take a look at the spreadsheets.

Roger, in a nutshell, what is the bottom line?

The bottom line in a nutshell? I'll try.

First, I added a note to both spreadsheets indicating that zero degrees
is CURRENT zero degrees. This because the source turns out to be
reactive, with current peak 45 degrees from voltage peak.

http://www.fairpoint.net/~rsparks/Sm...Reflection.pdf

I was not able to discern the derivation of the various equations
though the data in the columns looked somewhat reasonable. Were
the equation really based on the opening paragraph statement of
100 Vrms, or is it scaled to a different source voltage. The sin
functions have an amplituted of 100, which suggests a source of
200 volts or Vrms of 141.4 volts.

The spreadsheet addresses the following issues:

Does the traveling wave carry power? Yes. The spreadsheet was built
assuming that power is carried by traveling waves. Because the
resulting wave form and powers seem correct, the underlaying assumption
seems correct.

It was not obvious which columns were used to draw this correlation.

However, even if this experiment is consistent with the hypothesis
it only takes one experiment which is not to disprove the hypothesis.

Is power conserved on the transmission line, meaning, can the energy
contained in power be conserved and located over time on the
transmission line? Yes, the spreadsheet was built assuming that power
could be conserved and traced over time so the underlaying assumption
seems correct.

Does interference occur in this example? The spreadsheet was built
assuming that voltage and currents from superpose in a manner consistent
with constructive and destructive interference, so the underlaying
assumption seems correct.

Is power stored in the reactive component for release in later in the
cycle or during the next half cycle? Yes, power is stored on the
transmission line during the time it takes for power to enter the line,
travel to the end and return. The time of wave travel on the
transmission line is related to the value of the reactive component.

Does the direction of wave travel affect the measurement of voltage and
the application of power to a device? Yes. A wave loses energy (and
therefore voltage) as it travels through a resistance. As a result,
power from the prime source is ALWAYS applied across the sum of the
resistance from the resistor AND transmission line.

I am not sure that I would describe this as the wave losing energy,
but rather as the voltage dividing between the two impedances.
If the source resistance was replaced by another transmission,
which could easily be set to provide a 50 ohm impedance, would
you still describe it as the wave losing energy?

The spreadsheet was
built using this assumption and seems correct. (At times during the
cycle, the forward and reflected waves oppose, resulting in very little
current through the resistor. During those times, the power applied to
the transmission line is much HIGHER because the reflected wave reflects
from the load and source, and merges/adds to the forward wave from the
source.)

I am not convinced. When there is very little current through the
resistor,
there is also very little current into the transmission line. This
suggests to me that the power applied to the transmission line is low.

....Keith

On Sat, 29 Mar 2008 12:45:48 -0700 (PDT)
Keith Dysart wrote:

On Mar 27, 2:06 am, Roger Sparks wrote:
Cecil Moore wrote:
Roger Sparks wrote:
You need to take a look at the spreadsheets.

Roger, in a nutshell, what is the bottom line?

The bottom line in a nutshell? I'll try.

First, I added a note to both spreadsheets indicating that zero degrees
is CURRENT zero degrees. This because the source turns out to be
reactive, with current peak 45 degrees from voltage peak.

http://www.fairpoint.net/~rsparks/Sm...Reflection.pdf

I was not able to discern the derivation of the various equations
though the data in the columns looked somewhat reasonable. Were
the equation really based on the opening paragraph statement of
100 Vrms, or is it scaled to a different source voltage. The sin
functions have an amplituted of 100, which suggests a source of
200 volts or Vrms of 141.4 volts.

I simplified and changed the phase for the equation in column C from '100sin(wt-90) + 100sin(wt-180)' to '100sin(wt+90) + 100sin(-wt)' so that the total voltage in column D better matches with the voltages from my formula in column G.

The equation for column B is just the sine wave for the base wave, showing the voltage resulting to the source resistor from the peak current. The equation in column C is the same (from current) but recognizes that current from the reflected wave will cancel the current from the forward wave coming through Rs. The two waves are traveling in opposite directions so one angle must be labeled with a negative sign so that it will rotate in the opposite direction. In column C, the first term is the reflected wave and the second term is the base wave.

My formula, displayed in column G, uses the applied voltage of 141.4 volts. I thought it would be easier to see how the spreadsheet was built using current to find the voltages. You can see how the results of column D match well with those from column G.


The spreadsheet addresses the following issues:

Does the traveling wave carry power? Yes. The spreadsheet was built
assuming that power is carried by traveling waves. Because the
resulting wave form and powers seem correct, the underlaying assumption
seems correct.

It was not obvious which columns were used to draw this correlation.


Column E and column F display power. Column F recognizes that if 100 watts is applied continueously (on the average) over an entire 360 degree cycle, the final power applied over time would be 360 * 100 = 36000 watt-degrees. Part of the power comes from the reflection, part comes directly. Obviously, interference is very much at work in this example.

However, even if this experiment is consistent with the hypothesis
it only takes one experiment which is not to disprove the hypothesis.


True!

Is power conserved on the transmission line, meaning, can the energy
contained in power be conserved and located over time on the
transmission line? Yes, the spreadsheet was built assuming that power
could be conserved and traced over time so the underlaying assumption
seems correct.

Does interference occur in this example? The spreadsheet was built
assuming that voltage and currents from superpose in a manner consistent
with constructive and destructive interference, so the underlaying
assumption seems correct.

Is power stored in the reactive component for release in later in the
cycle or during the next half cycle? Yes, power is stored on the
transmission line during the time it takes for power to enter the line,
travel to the end and return. The time of wave travel on the
transmission line is related to the value of the reactive component.

Does the direction of wave travel affect the measurement of voltage and
the application of power to a device? Yes. A wave loses energy (and
therefore voltage) as it travels through a resistance. As a result,
power from the prime source is ALWAYS applied across the sum of the
resistance from the resistor AND transmission line.

I am not sure that I would describe this as the wave losing energy,
but rather as the voltage dividing between the two impedances.
If the source resistance was replaced by another transmission,
which could easily be set to provide a 50 ohm impedance, would
you still describe it as the wave losing energy?


It should be OK to think of the voltage dividing between two impedances. The important thing is to consider how the reflected voltage sums with the forward voltage where it is measured. Because the two waves are traveling in opposite directions, the measured voltage is not the voltage applied to either Rs or the transmission line. This is why columns B and C must be added to find the total voltage across Rs.

The spreadsheet was
built using this assumption and seems correct. (At times during the
cycle, the forward and reflected waves oppose, resulting in very little
current through the resistor. During those times, the power applied to
the transmission line is much HIGHER because the reflected wave reflects
from the load and source, and merges/adds to the forward wave from the
source.)

I am not convinced. When there is very little current through the
resistor,
there is also very little current into the transmission line. This
suggests to me that the power applied to the transmission line is low.

I don't follow you here. Right, power into the transmission line is low when the current in is low, and it is high when the current is high. It is clear that peak current and peak voltage do not occur at the same time except when measured across the resistor in column D.


...Keith


This is just one example, but it seems like the power is accounted for here. We need another example where power can NOT be accounted for.

--
73, Roger, W7WKB