Cecil Moore wrote:
Really? It doesn't act like a reflection. There isn't a reflective
surface.

Of course, it acts like a reflection and of course there is a reflective
surface if it is non-glare glass or a point if it is in a transmission
line. It is exactly what Walt has dubbed a "virtual short" and it is
a short for voltage, but not for current.

I remember when you were just as dubious about this as I am. How does
something that isn't a real short - and apparently doesn't even act like
a real short - cause real reflections? I'm not saying it doesn't. I'm
just saying that if you know how, please explain it. Thanks.

73, Jim AC6XG

Reg Edwards wrote:
"Cecil Moore" wrote
I'm talking about one particular transmission line,

Cec, you can't talk about one particular transmission line in an argument in
favour of anything in general.

Reg, you remind me of the lady at the DMV in California. I told her
that I took my ham plates off my camper and put them on my pickup.
She said I couldn't do that. I told her, sorry, I already did that.
--
73, Cecil http://www.qsl.net/w5dxp



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Jim Kelley wrote:
How does
something that isn't a real short - and apparently doesn't even act like
a real short - cause real reflections? I'm not saying it doesn't. I'm
just saying that if you know how, please explain it. Thanks.

I can't explain how but I certainly can explain why.

There are only two directions of energy flow available in a transmission
line. Since destructive interference occurs in one direction at a match
point, constructive interference must occur in the other direction. It's
all explained on the Melles-Groit web page and in _Optics_, by Hecht.
--
73, Cecil http://www.qsl.net/w5dxp




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Cecil Moore wrote:

Jim Kelley wrote:
How does
something that isn't a real short - and apparently doesn't even act like
a real short - cause real reflections? I'm not saying it doesn't. I'm
just saying that if you know how, please explain it. Thanks.

I can't explain how but I certainly can explain why.

I know why - because it's the only way you can understand. It just
doesn't happen to be true - as evidenced by the lack of any physical
explanation for it.

73, Jim AC6XG

Jim Kelley wrote:

Cecil Moore wrote:
I can't explain how but I certainly can explain why.

I know why - because it's the only way you can understand. It just
doesn't happen to be true - as evidenced by the lack of any physical
explanation for it.

The 'why' is conservation of energy. If there are only two directions
available and energy was traveling in one direction and now it isn't,
it's a no-brainer to realize that it must have changed directions.

I'm sorry that you don't believe in the conservation of energy theorem,
Jim. Do you boss know that?

So far you have failed every challenge to disprove the why. Wonder why?
--
73, Cecil http://www.qsl.net/w5dxp



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Cecil Moore wrote:

I'm sorry that you don't believe in the conservation of energy theorem,
Jim. Do you boss know that?

Thankfully you're the only one who deludes himself with this notion,
Cecil. Energy moves from source to load. It doesn't bounce back and
forth on it's way. That's what my "boss" believes - as I have explained
to you previously, in great detail.

73, Jim AC6XG

"Cecil Moore" wrote in message
...
The 'why' is conservation of energy. If there are only two directions
available and energy was traveling in one direction and now it isn't,
it's a no-brainer to realize that it must have changed directions.

Cecil, I think a more convincing argument is that I can take a slotted line
and directly measure a standing wave on it. A wave traveling in one
direction can not do that. Or am I cunfusing things?

Tam/WB2TT

Jim Kelley wrote:
Energy moves from source to load. It doesn't bounce back and
forth on it's way.

Shirley, you jest. That means you have never seen your
reflection in a mirror. (If I were you, I wouldn't be
able to stand looking myself in the eye either.)
--
73, Cecil http://www.qsl.net/w5dxp



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Tam/WB2TT wrote:

"Cecil Moore" wrote in message
...
The 'why' is conservation of energy. If there are only two directions
available and energy was traveling in one direction and now it isn't,
it's a no-brainer to realize that it must have changed directions.

Cecil, I think a more convincing argument is that I can take a slotted line
and directly measure a standing wave on it. A wave traveling in one
direction can not do that. Or am I cunfusing things?

Tam/WB2TT

No. That's right. But the point is - how much energy is actually
moving past the probe? Cecil seems to believe that a standing wave is
more than a superposition of voltages. It would be easy to mistake that
as a superposition of energies. But one can only superpose vector
quantities.

73, Jim AC6XG

whoa
system is: source - line - load
If there are impedance mismatches, in the steady state (ie 3 microseconds
after key down);
There will be more energy in the transmission line and the source than there
would be if all the impedances were matched.
This is necessary to satisfy the boundary conditions imposed on Maxwell's
Equations at each end of the transmission line.

The losses are the rent you pay for storing the energy; See bazookas for a
good example.

To the radiated energy moving past the probe one must add the losses.

That's why I prefer antennas with no reflections.
Reflect on that.

If you really want a book Paul Dirac's "Quantum Mechanics" is sweet.
Or Hawking's "The Large Scale Structure of Space-Time."


My cat, Hiram P Maxim (Max for short, he likes sleeping on the S-Line I've
had since '63), just walked over the keys and approves.

73
H.
NQ5H


"Jim Kelley" wrote in message
...


Tam/WB2TT wrote:

"Cecil Moore" wrote in message
...
The 'why' is conservation of energy. If there are only two directions
available and energy was traveling in one direction and now it isn't,
it's a no-brainer to realize that it must have changed directions.

Cecil, I think a more convincing argument is that I can take a slotted
line
and directly measure a standing wave on it. A wave traveling in one
direction can not do that. Or am I cunfusing things?

Tam/WB2TT

No. That's right. But the point is - how much energy is actually
moving past the probe? Cecil seems to believe that a standing wave is
more than a superposition of voltages. It would be easy to mistake that
as a superposition of energies. But one can only superpose vector
quantities.

73, Jim AC6XG