Cecil Moore wrote:

Walter Maxwell wrote:
But Cecil, take another look at Fig 6 on page 23-5 to note that those
two waves arrive 180 out of phase at point A, which means only that
the E and H fields cancel in the rearward direction only, resulting
in a Zo match to the source.

Yes, and that is exactly my point. EXACTLY the same thing happens to the
E-fields and H-fields. That means exactly the same thing that happens to
the rearward-traveling voltages also happens to the rearward-traveling
currents.

In my class in secondary school counseling, I learned a technique that
might be helpful here. It's called, "Be the thing." Whatever it is that
you are trying to understand, mentally become that thing. In other words,
assume that you are the reflected current to find out what you
would experience. Obviously, it is just a mental exercise, but one
that I have found quite useful throughout the years.

First, assume that you are the reflected voltage from a mismatched load.
What do you encounter back at the match point? You encounter another
reflected voltage with equal magnitude and opposite phase traveling in
the same rearward direction. What happens to you? Your momentum in the
rearward direction is reversed and your energy starts flowing toward the
load. As a reflected voltage, based on your necessarily limited knowledge,
you assume that you must have encountered a virtual short circuit.

Second, assume that you are the reflected current from a mismatched load.
What do you encounter back at the match point? You encounter another
reflected current with equal magnitude and opposite phase traveling in
the same rearward direction. What happens to you? Your momentum in the
rearward direction is reversed and your energy starts flowing toward the
load. As a reflected current, based on your necessarily limited knowledge,
you assume that you must have encountered a virtual open circuit.

There exists an apparent contradiction. A match point cannot simultaneously
be a virtual short and a virtual open. How is the apparent contradiction
resolved? Is there anything else in physics that can cause a total reflection
of energy besides a short, open, or pure reactance? The answer is, "yes", and
it happens all the time in the field of optics. In a system with only two
directions of energy travel available, total destructive interference in one
direction has to result in total constructive interference in the other
direction. That's the way perfect non-glare thin-film coated glass works in
the presence of a coherent single-frequency laser beam.
--
73, Cecil http://www.qsl.net/w5dxp



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

On Sat, 05 Jun 2004 13:05:18 -0500, Cecil Moore wrote:

Cecil Moore wrote:

Walter Maxwell wrote:
But Cecil, take another look at Fig 6 on page 23-5 to note that those
two waves arrive 180 out of phase at point A, which means only that
the E and H fields cancel in the rearward direction only, resulting
in a Zo match to the source.

Yes, and that is exactly my point. EXACTLY the same thing happens to the
E-fields and H-fields. That means exactly the same thing that happens to
the rearward-traveling voltages also happens to the rearward-traveling
currents.

In my class in secondary school counseling, I learned a technique that
might be helpful here. It's called, "Be the thing." Whatever it is that
you are trying to understand, mentally become that thing. In other words,
assume that you are the reflected current to find out what you
would experience. Obviously, it is just a mental exercise, but one
that I have found quite useful throughout the years.

First, assume that you are the reflected voltage from a mismatched load.
What do you encounter back at the match point? You encounter another
reflected voltage with equal magnitude and opposite phase traveling in
the same rearward direction. What happens to you? Your momentum in the
rearward direction is reversed and your energy starts flowing toward the
load. As a reflected voltage, based on your necessarily limited knowledge,
you assume that you must have encountered a virtual short circuit.

Second, assume that you are the reflected current from a mismatched load.
What do you encounter back at the match point? You encounter another
reflected current with equal magnitude and opposite phase traveling in
the same rearward direction. What happens to you? Your momentum in the
rearward direction is reversed and your energy starts flowing toward the
load. As a reflected current, based on your necessarily limited knowledge,
you assume that you must have encountered a virtual open circuit.

There exists an apparent contradiction. A match point cannot simultaneously
be a virtual short and a virtual open. How is the apparent contradiction
resolved? Is there anything else in physics that can cause a total reflection
of energy besides a short, open, or pure reactance? The answer is, "yes", and
it happens all the time in the field of optics. In a system with only two
directions of energy travel available, total destructive interference in one
direction has to result in total constructive interference in the other
direction. That's the way perfect non-glare thin-film coated glass works in
the presence of a coherent single-frequency laser beam.

Yes, Cecil, I understand. However I don't particularly like the notion of saying
both fields go to zero, or both fields go to zero in the rearward direction.
Confusing. Remember, weeks ago I swore that both fields could never go to zero
simultaneously? The reason I disagreed with you is that you didn't mention the
'direction'. The reason I dislike hearing that both fields go to zero is that
it's really not true. Like I've said many times, on encountering a short,circuit
voltage and the E field go to zero and the current and H field doubles AND
REVERSES DIRECTION. To me, Reversing direction is more meaningful and less
confusing than both going to zero, and it still says there is no energy
propagating rearward of the match point.

Going now to the cancellation process when the voltages and currents of both
waves are mutually out of phase. You say that voltages 180 out yields a short
(agreed) and that currents 180 out yields an open. Sounds good, and I mistakenly
agreed a coupla days ago. But I don' think so. I believe voltage 180 out defines
a short--period. Look at it this way. Take a zip cord and put male plugs on both
ends. Plug one end into an outlet, say the top one, and then plug the other end
into the bottom outlet with the polarities reversed. With respect to voltage we
have a 'circuit breaker' short circuit, because the voltages entering the zip
cord at each end were 180 out. But so were the currents initially. Then why the
short circuit current flow? Certainly not because the circuit is open to
current.

Another scenario with the same initial conditions and results: Take two
identical generators delivering the same level of harmonically related output
voltages. Connect their terminals in phase.Voltages in phase--currents in phase.
Result? No current flow. Why? Zero voltage differential. Open circuit to
voltage--open circuit to current.

Now reconnect their terminals in the opposite manner. Voltages 180 out--currents
180 out. Do we have current flow? You bet--dead short! Because current results
from voltage, if voltages are 180 out of phase we have a short to both voltage
and curent. No open circuit to current.

Cecil, I hope we're both still on the same page on this one;

Walt

Walter Maxwell wrote:
Yes, Cecil, I understand. However I don't particularly like the notion of saying
both fields go to zero, or both fields go to zero in the rearward direction.

But Walt, that's exactly what happens when total destructive interference
occurs as explained by J. C. Slater in _Microwave_Transmission_.

I believe voltage 180 out defines a short--period.

That same belief is what got Dr. Best into trouble. He never considered
what happens to the reflected current waves. In a sense, your and his
disagreements are because you both made the same conceptual mistake and
arrived at different conclusions because of that common mistake. If you
and he had not made that shared mistake, you both would have arrived at
the same conclusions.

Another scenario with the same initial conditions and results: Take two
identical generators delivering the same level of harmonically related output
voltages. Connect their terminals in phase.Voltages in phase--currents in phase.
Result? No current flow. Why? Zero voltage differential. Open circuit to
voltage--open circuit to current.

Now reconnect their terminals in the opposite manner. Voltages 180 out--currents
180 out. Do we have current flow? You bet--dead short! Because current results
from voltage, if voltages are 180 out of phase we have a short to both voltage
and curent. No open circuit to current.

This is the problem with trying to use circuit analysis to replace network analysis.
Put the two sources at the two ends of a transmission line and please reconsider
the outcome. Equip the two sources with circulators and dummy loads so the outcome
cannot be in doubt.
--
73, Cecil http://www.qsl.net/w5dxp



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

On Sat, 05 Jun 2004 15:23:37 -0500, Cecil Moore wrote:

Walter Maxwell wrote:
Yes, Cecil, I understand. However I don't particularly like the notion of saying
both fields go to zero, or both fields go to zero in the rearward direction.

But Walt, that's exactly what happens when total destructive interference
occurs as explained by J. C. Slater in _Microwave_Transmission_.

I believe voltage 180 out defines a short--period.

That same belief is what got Dr. Best into trouble. He never considered
what happens to the reflected current waves. In a sense, your and his
disagreements are because you both made the same conceptual mistake and
arrived at different conclusions because of that common mistake. If you
and he had not made that shared mistake, you both would have arrived at
the same conclusions.

Cecil, how do you figure I made a mistake in this issue? I have always
considered voltage 180 out as a short. And my writings show voltage at 180 as a
short, as stated on page 23-9. I agree that the opposite phases of both voltage
and current in that discussion resulted in the cancelation of reflected power
traveling in the 225-ohm section of line. And during the last day or two I
leaned toward thinking the out of phase current implied an open circuit. But you
can see from my words above that voltage rules--when the voltages are 180 out of
phase it defines a short circuit. My zip cord example is evidence to that.
Consequently, I don't agree that Steve and I made the same mistake. My writings
delivered the correct mathematical answers--Steve's does not. The mistake I made
on page 23-9 is in overlooking that it is the effective open circuit condition
seen looking in the rearward direction by the reflected waves at point A is what
gave both the voltage and current waves the reversal and phase change to zero
relative to the source waves.

Another scenario with the same initial conditions and results: Take two
identical generators delivering the same level of harmonically related output
voltages. Connect their terminals in phase.Voltages in phase--currents in phase.
Result? No current flow. Why? Zero voltage differential. Open circuit to
voltage--open circuit to current.

Now reconnect their terminals in the opposite manner. Voltages 180 out--currents
180 out. Do we have current flow? You bet--dead short! Because current results
from voltage, if voltages are 180 out of phase we have a short to both voltage
and curent. No open circuit to current.

This is the problem with trying to use circuit analysis to replace network analysis.
Put the two sources at the two ends of a transmission line and please reconsider
the outcome. Equip the two sources with circulators and dummy loads so the outcome
cannot be in doubt.

Cecil, I don't believe the outcome is in doubt.

Walt

Walter Maxwell wrote:
But you
can see from my words above that voltage rules--when the voltages are 180 out of
phase it defines a short circuit.

This is exactly the same mistake that Dr. Best made. *VOLTAGE DOESN'T RULE!*
Current is *equally* important to voltage. If you had assumed that "current
rules", you would be saying - "when the currents are 180 out of phase it
defines an open circuit".

My argument is actually a minor point but bridges part of the gap between
you and Dr. Best. (And absolutely nothing being discussed here concerns
the source impedance of a transmitter. All we are discussing is what
happens at a match point in a transmission line or at a tuner.)
--
73, Cecil http://www.qsl.net/w5dxp



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

On Sat, 05 Jun 2004 19:20:18 -0500, Cecil Moore wrote:

Walter Maxwell wrote:
But you
can see from my words above that voltage rules--when the voltages are 180 out of
phase it defines a short circuit.

This is exactly the same mistake that Dr. Best made. *VOLTAGE DOESN'T RULE!*
Current is *equally* important to voltage. If you had assumed that "current
rules", you would be saying - "when the currents are 180 out of phase it
defines an open circuit".

Then how can you explain what happens when you reverse the zip cord, plugging
one end in one way and the other with the prongs reversed ? Are you saying the
currents in this condition are seeing an open circuit?

My argument is actually a minor point but bridges part of the gap between
you and Dr. Best. (And absolutely nothing being discussed here concerns
the source impedance of a transmitter. All we are discussing is what
happens at a match point in a transmission line or at a tuner.)

Walter Maxwell wrote:
Then how can you explain what happens when you reverse the zip cord, plugging
one end in one way and the other with the prongs reversed ? Are you saying the
currents in this condition are seeing an open circuit?

I'm sorry, Walt, you lost me. What zip cord?
--
73, Cecil http://www.qsl.net/w5dxp



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

On Sat, 05 Jun 2004 20:06:48 GMT, Walter Maxwell wrote:
Cecil, I hope we're both still on the same page on this one;
Same page, different books....

Hi Walt,

Let's see, the score is one argument, two correspondents, and three
explanations. Do you know where Cecil is? Used to be "Find Waldo."

73's
Richard Clark, KB7QHC