Tdonaly wrote:
Yep, and you're changing the subject. How does that wave, that flip flops
like a jump rope, move in and out of your coil?

Approximately the same way it does on a transmission line. When the
forward and reflected current are in phase at zero degrees, both are
flowing toward the load. Therefore, their sum (standing wave current
positive maximum) is flowing toward the load. When the forward and
reflected current are in phase at -180 degrees, both are flowing toward
the source. Therefore, their sum (standing wave current negative maximum)
is flowing toward the source. (This assumes that the source output is
the zero phase reference.) The standing wave reverses phase every 1/2
cycle. From Kraus: "... the phase is constant over a 1/2WL interval,
changing abruptly by 180 degrees between intervals."

Install a one ohm resistor at a current loop. Observe the voltage.
That voltage is a sine wave, proportional to the current, changing
polarity (direction) every 1/2 cycle. RF current simply cannot stand
still.

In a wire driven by an AC source, the current flows away from the source
for 1/2 cycle and then flows toward the source for 1/2 cycle. In a multi-
wavelength RF transmission line, the individual electrons may never make
it from the source to the load. Some electrons are just pumped back and
forth through the source.
--
73, Cecil http://www.qsl.net/w5dxp



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On Fri, 06 Feb 2004 22:08:12 -0600, Cecil Moore
wrote:
reflected current ...
flowing toward the load.
Uh-huh

On Fri, 06 Feb 2004 22:08:12 -0600, Cecil Moore
wrote:
forward ... current ... flowing toward
the source.
Uh-huh

Cecil, W5DXP wrote:
"Nope, it`s not. (phase difference between forward and reflected waves
locked in phase)."

At any specific point on a transmission line, the phase angle between
the incident and reflected waves is unvarying. That`s what makes
standing waves.

At any specific point on a transmission line, the incident wave arrives
a fixed number of degrees after its departure from the transmitter.If
there is a reflected wave it is delayed by the time it takes to travel
the route of the incident wave, plus the delay in traveling the
aditional path to the reflection point. Then, either the voltage or the
current is going to experience a phase reversal upon reflection. If the
load impedance on the transmission line is too high, the current
undergoes a phase reversal upon reflection. If the load impedance on the
transmission line is too low, the voltage undergoes a phase reversal
upon reflection. Then the reflected wave still must take more time to
come back from its reflection point to the point "P" on the line where
we are considering the phases and magnitudes of the incident and
reflected waves.

Terman says on page 95 of his 1955 4th edition:
"However, irrespective of the relative amplitudes of incident and
reflected waves, the phase of both voltage and current will advance
exactly pi radians (180-degrees) when the distance toward the generator
decreases by a half wavelength. Although in the absence of a reflected
wave the variation in phase is at a uniform rate within this distance,
this is not the case when a reflected wave is present."

Terman is looking at the sums of incident and reflected waves above.
Back on page 89 he was considering incident and reflected waves
separately when there has has been a reflection from an open circuit.
Terman says:

"Consider now how these two waves behave as distance l from the load
increases. The incident wave advances in phase beta radians per unit
length, while the reflected wave lags correspondingly; at the same time
magnitudes do not change greatly when the attenuation constant alpha is
small."

Terman is saying that as you look at points closer to the generator you
aare looking at the emerging wave sooner in its history, but for the
reflected wave the same points show the wave after it has more history
paradoxically as you move closer to the generator.

Best regards, Richard Harrison, KB5WZI

Cecil Moore
...Standing waves don't stand still...
http://einstein.byu.edu/~masong/HTMs...newave2EX.html

Good grief ! Semantic nonsense.

Ref. webpage (URL above):
1) Red wave moving (has direction: right).
2) Green wave moving (has another direction: left).
3) Black wave is (by any reasonable definition) NOT MOVING. Neither
left nor right. It has no direction. It IS standing still.

YOU WILL NOTE THAT THE WEBPAGE EVEN HAS TWO ARROWS AT THE TOP
INDICATING THE DIRECTIONS FOR THE TWO WAVES THAT ARE NOT STANDING
STILL - THE RED AND GREEN WAVES. IT DOESN'T HAVE A THIRD ARROW FOR
THE BLACK STANDING WAVE.

Of course, the black wave is still 'AC' (a pointlessly obvious point).
It might be worth pointing out this 'duh!-obvious' up-and-down motion
of the black standing wave to eager RF newbies, but it is not worth
making an argument.

Cecil, your point is pure, unadulterated semantic nonsense.

"J. Harvey" wrote in message
om...
Cecil Moore
...Standing waves don't stand still...
http://einstein.byu.edu/~masong/HTMs...newave2EX.html

Good grief ! Semantic nonsense.

Ref. webpage (URL above):
1) Red wave moving (has direction: right).
2) Green wave moving (has another direction: left).
3) Black wave is (by any reasonable definition) NOT MOVING. Neither
left nor right. It has no direction. It IS standing still.

YOU WILL NOTE THAT THE WEBPAGE EVEN HAS TWO ARROWS AT THE TOP
INDICATING THE DIRECTIONS FOR THE TWO WAVES THAT ARE NOT STANDING
STILL - THE RED AND GREEN WAVES. IT DOESN'T HAVE A THIRD ARROW FOR
THE BLACK STANDING WAVE.

Of course, the black wave is still 'AC' (a pointlessly obvious point).
It might be worth pointing out this 'duh!-obvious' up-and-down motion
of the black standing wave to eager RF newbies, but it is not worth
making an argument.

Cecil, your point is pure, unadulterated semantic nonsense.

lets have more fun... the 'standing wave' isn't really a wave at all. it
doesn't move, it doesn't transfer energy, it really doesn't do anything
except sit there.... and part of the time it doesn't even exist, being zero
at all points along the line at the same time when the two traveling waves
cancel each other. so i propose that the term 'standing wave' is a complete
misnomer and in fact is probably an oxymoron and should be abolished, along
with the term 'standing wave ratio' and the infamous (at least in the news
group) 'swr meter'!

ok, i'll go back to lurking now.

Richard Clark wrote:

On Fri, 06 Feb 2004 22:08:12 -0600, Cecil Moore
wrote:

forward ... current ... flowing toward
the source.

Uh-huh

Richard, do you actually believe that 60 Hz AC current flows the same direction
all the time into your refrigerator? Wouldn't that make it DC? AC current
flows into the refrigerator for 1/2 cycle and flows out of the refrigerator
during the next 1/2 cycle. In the AC hot wire, AC current flows toward the
generator just as often as it flows toward the refrigerator. Every 8.333 mS,
it goes through a zero-crossing and changes direction.
--
73, Cecil http://www.qsl.net/w5dxp



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Richard Harrison wrote:

Cecil, W5DXP wrote:
"Nope, it`s not. (phase difference between forward and reflected waves
locked in phase)."

At any specific point on a transmission line, the phase angle between
the incident and reflected waves is unvarying. That`s what makes
standing waves.

That you were talking about "at any specific point" wasn't apparent
to me from your following assertion. I apologize for misunderstanding.

To keep it simple, phase difference between forward and reflected waves
is locked.
--
73, Cecil http://www.qsl.net/w5dxp



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J. Harvey wrote:
3) Black wave is (by any reasonable definition) NOT MOVING. Neither
left nor right. It has no direction. It IS standing still.

The Black wave loop is moving up and down indicating that the
phase is changing from positive to negative. The cosine of the
phase angle indicates the direction of current flow. How can
you say it has no direction? And only a blind person would assert
that the current loop is standing still while moving up and down.
Current that stands still is zero current.

A jump rope is a standing wave. Do you also assert that a jump
rope in motion is standing still?
--
73, Cecil http://www.qsl.net/w5dxp



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Dave wrote:
lets have more fun... the 'standing wave' isn't really a wave at all. it
doesn't move, it doesn't transfer energy, it really doesn't do anything
except sit there.... and part of the time it doesn't even exist, being zero
at all points along the line at the same time when the two traveling waves
cancel each other. so i propose that the term 'standing wave' is a complete
misnomer and in fact is probably an oxymoron and should be abolished, along
with the term 'standing wave ratio' and the infamous (at least in the news
group) 'swr meter'!

Like a traveling wave, a standing wave changes phases except at the nodes.
In fact, by looking at only one toroidal pickup at one point on the line
(anywhere except a node) you cannot tell if that current wave is standing
or traveling or both.

And the standing wave does transfer energy from the source to the I^2*R
losses in the transmission line. That's why feedlines with high standing
wave ratios are lossier than matched lines.
--
73, Cecil http://www.qsl.net/w5dxp



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