"Richard Clark" wrote -
"It was the best of times, it was the worst of times."

=============================

Richard, now you're plagiarising Charles Dickens.
----
Reg.

"Reg Edwards" wrote in message
...

"Richard Clark" wrote -
"It was the best of times, it was the worst of times."

=============================

Richard, now you're plagiarising Charles Dickens.
----
Reg.

Cecil, define 'sloshing.'

Walt,W2DU

Walter Maxwell wrote:

Cecil, define 'sloshing.'

Hi Walt, I'm having trouble with my news-server so I am posting from
Google using procedures to which I am not accustomed.

The classic wave reflection model indicates that forward power travels
from the source to the load where it is incident upon the load. At a
load mismatch, some of the forward power is rejected and travels back
from the load toward the source as a reflected wave. For instance, in
the following lossless example, we have 104.17 watts of forward wave
and 4.17 watts of reflected wave on the 75 ohm line. This is all in
line with "Reflections" and my unpublished article.

100W--50 ohm line--+--1/4WL 75 ohm line---112.5 ohm load

As I infer/understand what Roy, and others, have said while objecting
to the material in my unpublished article:

The only real forward power wave is the one that is dissipated in the
load. The reflected power wave doesn't travel from the load back toward
the source and the extra 4.17 watts in the forward wave doesn't travel
from the match point back toward the load. The energy associated with
the reflected waves just "sloshes" around in the transmission line and
doesn't move very far or very fast and certainly not in the form of EM
wave components.

So Roy's use of the word "slosh" in the context in which he used it, is
all I can give you. Roy hasn't defined the word and neither has the
IEEE. :-)
--
73, Cecil http://www.qsl.net/w5dxp

Cecil, W5DXP, quoting others, wrote:
"The reflected power wave doesn`t travel from the load back toward the
source and the extra 4.17 watts in the forward wave doesn`t travel from
the match point back toward the load."

Users of the Bird and Similar wattmeters know that is what they see.
Source and load power is the forward power minus the reflercted power.

Zo of the coax enforces its volt to amp ratio on both the incident and
reflected waves. Reflected power is again reflected at the match point
because the matched source sees no reflection. That`s the point of
producing a match in the load.

Best regards, Richard Harrison, KB5WZI

Richard Harrison wrote:

Users of the Bird and Similar wattmeters know that is what they see.
Source and load power is the forward power minus the reflercted power.

But that's only what is printed on the meter scale. It doesn't make the
"reflected power" real.

For the (n+1)th time: the Bird so-called "wattmeter" does NOT sense
forward and reflected power. It only senses RF voltage and current on
the line. The meter scale calibration is a mathematical operation that
depends on a lot of assumptions... most notably the assumption that
"reflected power" has some physical reality.

I am genuinely open-minded about that debate - which makes the all the
more determined to be ruthless about bogus arguments on either side.

And the most bogus argument of all is: "Users of the Bird and Similar
wattmeters know that is what they see."


--
73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

Ian White GM3SEK wrote:
But that's only what is printed on the meter scale. It doesn't make the
"reflected power" real.

I am genuinely open-minded about that debate - which makes the all the
more determined to be ruthless about bogus arguments on either side.

Ian, correct me if I'm wrong, but I infer that you are biased
toward the "no reflected energy waves" side. That bias could be
based on perceived knowledge.

Seems to me, some people are begging the question. They assume
there is no energy in reflected waves and call what the other
side says, "gobbleygook", even when presented in scientific
terms. I think we all understand the concepts behind net
energy. What is in dispute is the next lower layer of dynamic
energy movement in both directions at the same time during
steady-state.

So would you explain what happens to the reflections of a laser
beam when aimed at a perfect mirror in free space. Offset the
laser beam slightly from normal incidence to start with and
observe the reflections with your naked eye. Then bring the
beam to 90 degree incidence with the mirror. You can no
longer see the reflections but now you can detect the
superposition of the forward and reflected waves through
interference "rings" or loops with an intensity maximum
occuring every half wavelength and an intensity minimum
occuring every half wavelength in between.

Where is the EM wave energy just sloshing around and not
traveling forward and rearward at the speed of light?
--
73, Cecil http://www.qsl.net/w5dxp

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Cecil Moore wrote:
But that's only what is printed on the meter scale. It doesn't make
the "reflected power" real.
I am genuinely open-minded about that debate - which makes the all
the more determined to be ruthless about bogus arguments on either
side.

Ian, correct me if I'm wrong, but I infer that you are biased
toward the "no reflected energy waves" side. That bias could be
based on perceived knowledge.

I am trying very hard not to be biased about the actual problem -
but I am very much against your methods of debate.

Why should anyone consent to follow you into the realms of optics and
laser physics, merely because that's where you want to go? Stand your
ground right here on the log, Cecil, and talk strictly and exclusively
about RF transmission lines.


--
73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

Cecil Moore wrote:
So would you explain what happens to the reflections of a laser
beam when aimed at a perfect mirror in free space? Offset the
laser beam slightly from normal incidence to start with and
observe the reflections with your naked eye. Then bring the
beam to 90 degree incidence with the mirror. You can no
longer see the reflections but now you can detect the
superposition of the forward and reflected waves through
interference "rings" or loops with an intensity maximum
occuring every half wavelength and an intensity minimum
occuring every half wavelength in between.

Incidentally, there is a very good discussion of standing waves
in section 7.1.4 of "Optics", by Hecht, 4th Edition.
--
73, Cecil http://www.qsl.net/w5dxp

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Richard Harrison wrote:

Reflected power is again reflected at the match point
because the matched source sees no reflection.

I think you put your finger on it, Richard. That's exactly what
inspired the 'sloshing energy' comment.

73, ac6xg

Jim Kelley wrote:
Richard Harrison wrote:

Reflected power is again reflected at the match point
because the matched source sees no reflection.

I think you put your finger on it, Richard. That's exactly what
inspired the 'sloshing energy' comment.

Except that the "sloshing energy" comment doesn't have the energy
sloshing from the load to the match point and back at the speed of
light. As I understand the concept of "sloshing energy" it is sloshing
back and forth rather locally between the inductance and the
capacitance.
--
73, Cecil http://www.qsl.net/w5dxp