Richard Harrison wrote:
Which is cause and which is effect? Often what is cause and what is
effect can be interchanged. Volts across a resistor produce a current.
Current in a resistor produces a voltage drop. Take your pick of cause
or effect.

A resistor's resistance *causes* a certain V/I ratio. If there exists
a V/I ratio and no resistor, then the V/I ratio is the *cause* of the
resistance (or impedance). In other words, a resistorless resistance
cannot be the cause of anything. It is always an effect, often from
interference, and is usually lossless. Note that anything that suffers
from I^2*R dissipation is a resistor by this definition. That includes
a piece of copper wire.

A reflection may be caused by a phase reversal between voltage and
current.

We are past discussing reflections. The present argument is: Given two
coherent waves traveling in the same path with the same magnitude and
opposite phases, wave cancellation results from destructive interference.

The laws of physics tells us that energy cannot be destroyed and if
destructive interference exists, an equal magnitude of constructive
interference is required to exist. The destructive interference in
a Z0-matched system is toward the source. The constructive interference
in a Z0-matched system is toward the load. The energy components involved
in those two types of interference are traveling in opposite directions.

The conclusion is obvious. The reflected energy involved in the wave
cancellation process heads back toward the load just as explained on
the Melles-Griot web page. That there is such a large well-organized
good old boy conspiracy trying to hide these simple facts of physics
speaks volumes about the sad state of amateur radio.

http://www.mellesgriot.com/products/optics/oc_2_1.htm
--
73, Cecil, W5DXP

Richard Clark wrote:

wrote:
Your argument contains logical contradictions.

Because his sources acknowledge and perform to the teachings of
Einstein and the workers in the fields of Quantum physics which allow
such contradictions.

Well, I guess that settles that. A thing is not what it is.
Why didn't I think of simply denying reality? I think I get
it now. When you lose an argument using a certain math model,
declare that math model to be null and void.
--
73, Cecil, W5DXP

Cecil, W5DXP wrote:
"Given two coherent waves traveling in the same path with the same
magnitude and opposite phases, wave cancellation results from
destructive interference."

The waves don`t cancel out. Anything in their path just receives equal
and opposite influences and the effect of the waves is nil.
Sound cancellers which generate equal and opposite waves are an example.
Either the sound or antisound sources alone might be deafening, but
taken together, there is relative quiet.

Best regards, Richard Harrison, KB5WZI

On Fri, 12 Mar 2004 13:08:20 -0600, Cecil Moore
wrote:

We are past discussing reflections. The present argument is: Given two
coherent waves traveling in the same path with the same magnitude and
opposite phases, wave cancellation results from destructive interference.

The laws of physics tells us that energy cannot be destroyed and if
destructive interference exists, an equal magnitude of constructive
interference is required to exist. The destructive interference in
a Z0-matched system is toward the source. The constructive interference
in a Z0-matched system is toward the load. The energy components involved
in those two types of interference are traveling in opposite directions.

The conclusion is obvious. The reflected energy involved in the wave
cancellation process heads back toward the load just as explained on
the Melles-Griot web page. That there is such a large well-organized
good old boy conspiracy trying to hide these simple facts of physics
speaks volumes about the sad state of amateur radio.

http://www.mellesgriot.com/products/optics/oc_2_1.htm

It constantly amazes me that the majority of you guys on this thread just can't
seem to get (understand) the truth that Cecil's been trying to get through to
you. Where does the power in the cancelled reflected waves go? Conservation of
energy dictates that it is totally re-reflected when a complete impedance match
has been achieved. You want the wave mechanism that accomplishes this feat? I'll
get to that shortly.

In Steve Best's latest QEX article, Part 3, bottom of Page 43, beginning with
the section titled, "The Total Reflection Fallacy" and continuing ONLY on the
left column of Page 44, Steve tells it like it is, correctly. Then why does he
call it a Fallacy? Please be patient and I'll tell you why.

Steve' correct explanation of the matching process in that single column was
taken directly from my writings in ARRL journals. Paraphrased, yes, but
correctly so.

My first publication of this issue appeared in QST, October 1973, entitled, "A
View Into the Conjugate Mirror." This article appears in both Eds 1 and 2 of
Reflections as Chapter 4, Steve also copied from another of my articles, this
one in QEX,, Mar/Apr 1998, entitled "Examining the Mechanics of Wave
Interference in Impedance Matching," which also appears in Reflections 2 as
Chapter 23.

Steve and I have been in contentious controversy on this subject for several
years. He continued this controversy by publishing this totally erroneous
material in QEX,, erroneous except for the portion in the single column where he
presented my material correctly. The remaining portion of his article is simply
an unsuccessful attempt to show that my position is incorrect, and therefore
calls it a 'fallacy'.

In fact, however, the entire portion following the correct portion he copied
from me is where the REAL fallacy lies--it proves that he knows very little
about the subject of his title, "Wave Mechanics of Transmission Lnes." It also
shows he doesn't have a clue concerning the superposition of two rearward
traveling waves that are conjugately related at the matching point. In fact,
the two waves cancel each other, and establish either a one-way open circuit or
a one-way short circuit that totally re-reflects the reflected power, with its
voltage and current components traveling in the same phase as t;hose from the
source, and therefore adding to the source power.

I know that many on this thread believe that no open or short circuit can be
established by the superposition of waves. It is true that forward and reflected
waves, traveling in OPPOSITE directions establish only the standing wave--no
open or short circuits. But it's a different ball game when two waves traveling
in the SAME direction are conjugately related. The waves are conjugately related
because the canceling wave generated by the matching device is tailored to have
the same magnitude but opposite phase as the wave reflected from the mismatched
load on the transmission line.

Here's why a short or open circuit is established when conjugately related waves
join at a matching point. From an analytic viewpoint the voltage appearing at
any point on the line can be replaced with a generator delivering the same
voltage at the same phase that appears at that point. This generator is called a
'point' generator that delivers an impedance-less EMF. Now consider one
generator delivering the voltage appearing in the wave reflected at the
mismatched load and a second generator delivering the voltage from the canceling
wave reflected by a matching stub, or whatever the matching device, at the same
point on the line as the first. The voltage from this second generator has the
same magnitude, but opposite phase from that of the first generator. When the
voltages delivered by the t wo generators are 180 degrees out of phase we have a
short circuit--if they're in phase we have an open circuit. As the result, in
either of these two conditions no reflected wave can pass rearward of the
matching point.

From the simple fact that the impedance at the input of an antenna tuner is 50+
j0 we know that no reflected power is traveling rearward further than the tuner
input. Where did the power in the reflected wave go? That energy cannot
disappear as if by some sort of magic--it is totally re-reflected by the open or
short circuit, and adds to the source power to establish a forward power equal
to the sum of the source and reflected power.

I hope this helps to end the confusion, and also gives Cecil what he deserves
for his attempt to give you guys the straight dope.

Walt, W2DU

On Fri, 12 Mar 2004 13:28:37 -0600, Cecil Moore
wrote:
When you lose an argument using a certain math model,
declare that math model to be null and void.

You were expecting chopped liver?

Richard Harrison wrote:

Cecil, W5DXP wrote:
"Given two coherent waves traveling in the same path with the same
magnitude and opposite phases, wave cancellation results from
destructive interference."

The waves don`t cancel out. Anything in their path just receives equal
and opposite influences and the effect of the waves is nil.

I assume you are not asserting that canceled waves' effects become
nil, i.e. undetectable, until the end of time yet they still possess
the same amount of energy as always except now that energy is completely
undetectable for the rest of the life of the universe. Consider the
ramifications of what you are asserting.

Seems to me, canceled waves must *cease to exist* at a point in space-time
if they exhibit zero measurable evidence of their existence forever after
(plus exactly that same amount of energy is required by the system in the
opposite direction).

Incidentally, that was Dr. Best's argument. The energy in the canceled
waves continues to propagate forever in the opposite direction of the
load. Never mind, that exact same amount of energy is required for constructive
interference in the opposite direction and cannot just be created out
of nothing. That's when he left the newsgroup.

For constructive interference to exist, energy from destructive interference
MUST be supplied from somewhere real, according to Hecht in _Optics_.
The conservation of energy principle agrees with Hecht as it
did during the spring of '01 when the arguments were raging between
Dr. Best and me. There is still not enough energy only in P1 and P2 to
make P1 + P2 + 2*(P1*P2) equal to the forward power. The 2*(P1*P2) is
known in the field of optics as the "interference term" and obviously
is supplied from destructive interference between two reflected waves.
--
73, Cecil http://www.qsl.net/w5dxp



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Richard Clark wrote:

wrote:
When you lose an argument using a certain math model,
declare that math model to be null and void.

You were expecting chopped liver?

No, I was expecting a modicum of rationality - silly me.
--
73, Cecil http://www.qsl.net/w5dxp



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Cecil, W5DXP wrote:
"Seems to me, canceled waves must "cease to exist" at a point in space
time if they exhibit zero measurable evidence of their existence forever
after---."

A union of two waves can make them both disappear if they are exact
opposites, but elimination of just one of the two produces the the
other. Were the two waves actually annhilated by their coexistence on
the path together, they would not be exhibitable on demand by
turning-off one or the other constituent.

Best regards, Richard Harrison, KB5WZI

Richard Harrison wrote:

Cecil, W5DXP wrote:
"Seems to me, canceled waves must "cease to exist" at a point in space
time if they exhibit zero measurable evidence of their existence forever
after---."

A union of two waves can make them both disappear if they are exact
opposites, but elimination of just one of the two produces the the
other. Were the two waves actually annhilated by their coexistence on
the path together, they would not be exhibitable on demand by
turning-off one or the other constituent.

Of course they would, Richard, since the destructive interference ceases
when one of them is turned off. What happens while the two waves are
engaging in total destructive interference is that their combined energy
components flow in the opposite direction as a constructive interference
wave. That's why Melles-Griot says the rearward flowing "lost" energy
involved in the destructive interference is not lost at all and instead
joins the forward wave traveling in the opposite direction. That's why
the rearward-flowing reflected wave energy all winds up flowing toward
the load in a Z0-matched system.

Let's say I am a light year away from two interfering waves at your
location. I am measuring zero energy. You switch off one of the signals.
How long does it take for me to sense any energy? - a year because the
energy pipeline is empty before you switch off one of the signals.
There's no energy flowing toward me while both signals are on.
--
73, Cecil http://www.qsl.net/w5dxp



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Cecil, W5DXP wrote:
"You switch off one of the signals. How long does it take for me to
sense any energy?"

Yes, if the transit time is one year, that`s how long it takes to sense
any change in received signal.

I was wrong when I wrote waves would be exhibitable on demand were they
annhilated. Cecil was right. It makes no difference whether two equal
and opposite signals are received or no signal is received. Same result.

What happens at an open circuit on a transmission line? The current is
interrupted and must reverse direction as it has nowhere else to go. A
changed direction is a reversed polarity so incident and reflected
currents add to zero.

Energy in the magnetic field is eliminated by the addition to zero of
the incident and reflected currents. This canceled energy goes to the
only place it can go, into the electric field. This results in doubling
the voltage at the open-circuit end of the line.

In a short-circuit on a line, the current doubles and the voltage goes
to zero.

1/4-wave back from a short, a near open circuit exists. !/4-wave back
from an open or a short, conditions are inverted on a low-loss line.
Where there is an open-circuit at the end of a line, a near short
circuit exists 1/4-wave back.

I think that at the open circuit at the end of a line, the excess
voltage launches the reflected wave. At the short on a line, excess
current launches a reverse wave. Voltage produces current and current
produces voltage. Voltage and current are dominnated by the Zo of the
line in all movement through the line.

Cecil has argued that the high impedance at the open end of a shorted
1/4-wave stub does not inhibit current into the stub. The reflection
point is at the short, not at the high impedance point back 1/4-wave
from the short. That sounds reasonable to me, but I wonder if it makes
any difference.

Best regards, Richard Harrison, KB5WZI