There's a good fight brewing in QEX magazine land. Eric, K8LV, wrote a
pretty good article on directional wattmeters. But he spent a lot of
space asserting that the notion of forward and reflected power in a
transmission line is merely for intuitive convenience, isn't real, and
should be abandoned in favor of unidirectional power flow and lumped
analysis at a single point.

Whoo Hoo. The letters will be fun. Especially if Eric attempts to
extend his assertion to a case not-as-special, such as not-steady-state
or a point in 3D space.

Too bad it wasn't here. Bet we'd get a couple dozen posts before the
weekend's out. Anyone want to take Eric's side?


73,
Glenn AC7ZN

wrote:
There's a good fight brewing in QEX magazine land. Eric, K8LV, wrote a
pretty good article on directional wattmeters. But he spent a lot of
space asserting that the notion of forward and reflected power in a
transmission line is merely for intuitive convenience, isn't real, and
should be abandoned in favor of unidirectional power flow and lumped
analysis at a single point.

K8LV is like the person who is satisfied with the Sun God riding
his chariot across the sky every day as a model of reality. He seems
to believe in a Standing Wave God who wills standing waves into
existence without the necessity for a forward traveling wave and
a rearward traveling wave to exist. It reminds me of what Einstein
said about models of reality needing to be simple, but not too simple.

Over the years, I have challenged anyone on this newsgroup to create
a standing wave in a single source system without having the existence
of a forward wave and a reflected wave. Nobody has furnished any proof
that standing waves are possible in a single source system without the
existence of forward and reflected waves.

Reflected energy is readily apparent using a time domain reflectometer.
Reflected power is easily detected and dissipated using a signal
generator with a circulator and load. A bit of modulation proves that
the reflected wave has made a round trip to the mismatched load and
back to the circulator load.

With the following example, I have shown that, during steady-state,
there are 300 joules of energy in the transmission line that have
not yet reached the load.

100W---one second long 50 ohm lossless feedline---291.5 ohms
Pfor=200W-- --Pref=100W

There are no impedance discontinuities between the source and the
load and EM energy travels at the speed of light. The 300 joules
cannot exist anywhere except in the forward and reflected waves.
Without the existence of forward and reflected waves, there is
nothing to support standing waves. That the energy moving in each
direction is difficult to separate is no reason to assert that it
doesn't exist. According to the IEEE definition of power, the
*potential* for doing work is power. The 300 joules stored in the
above transmission line have the potential for doing work after
the source is powered down. That the work actually performed is
not useful work is irrelevant.

Anyone who doubts the existence of reflected energy should do a
second by second analysis of the above example starting at power
up. The technical facts become undeniable after a few seconds.

Whoo Hoo. The letters will be fun. Especially if Eric attempts to
extend his assertion to a case not-as-special, such as not-steady-state
or a point in 3D space.

Too bad it wasn't here. Bet we'd get a couple dozen posts before the
weekend's out. Anyone want to take Eric's side?

K8LV even contradicts himself in his own article. He says the Z0 of
the line "literally forces all power flow to occur in 50-ohm waves
on the line". In the above example, those 300 joules per second are
necessarily flowing in the one second long line since they cannot
stand still. Where are they if, as K8LV asserts, the Z0 of the line
is forcing a V/I ratio of 50 ohms? They can exist in only one place,
in the 200W forward wave and 100W reflected wave each of which forces
a V/I ratio of 50 ohms, just as K8LV asserts.

Exactly the same thing happens when standing EM waves of light are
formed in free space. Let's see K8LV explain that one without the
existence of forward traveling light waves and rearward traveling
light waves. How do these quotes agree with standing waves of light?

"... the forward and reverse waves do not exist separately ..."

I think I can hear a multitude of physicists laughing at the assertion
that standing waves of light do not require the separate existence of
forward and reverse waves. QEX was interested in publishing an article
of mine with light wave examples until they realized the implications
of those technical facts.

This is just one more example of the dumbing down of amateur radio
accompanying the dumbing down of the US educational system in
general. Unfortunately, it seems to be a trend that cannot be
reversed because it is the biased view being pushed by the ARRL
and its supporters.
--
73, Cecil http://www.qsl.net/w5dxp

Cecil Moore wrote:

Over the years, I have challenged anyone on this newsgroup to create
a standing wave in a single source system without having the existence
of a forward wave and a reflected wave. Nobody has furnished any proof
that standing waves are possible in a single source system without the
existence of forward and reflected waves.

Cecil,

Why would anyone try to prove that the basic math of adding sinusoidal
functions is incorrect? To the contrary, you are the one who insists
that a standing wave and its constituent traveling wave components are
somehow different and unique. No one denies the simultaneous existence
of standing waves and traveling waves.

Isn't superposition wonderful!

73,
Gene
W4SZ

Gene Fuller wrote:
Why would anyone try to prove that the basic math of adding sinusoidal
functions is incorrect? To the contrary, you are the one who insists
that a standing wave and its constituent traveling wave components are
somehow different and unique.

Actually, it was you who made that assertion and thanks for the
opportunity to quote you once again:

Gene Fuller, W4SZ wrote:
In a standing wave antenna problem, such as the one you describe,
there is no remaining phase information. Any specific phase
characteristics of the traveling waves died out when the startup
transients died out.

So standing waves are "somehow different" from traveling waves
according to your own assertions. The traveling wave possesses
phase characteristics and the standing wave doesn't.

Phase is gone. Kaput. Vanished. Cannot be recovered. Never to be
seen again.

So it was you who asserted that standing wave current is "somehow
different" from traveling wave current and I agree with you. It's
obvious they are "somehow different" because they have different
mathematical equations. Have you changed your mind since your
above quoted posting?

No one denies the simultaneous existence
of standing waves and traveling waves.

Of course they do, Gene, that is the whole point. Here is a quote
from K8LV's article:

"I wish to emphasize the fact that the forward and reverse
waves really do not exist separately ..."

That certainly *denies* the separate existence of the underlying
traveling waves so your above assertion is false. I believe that
W7EL also denies the separate existence of forward and reverse
waves and introduced the technical term, "sloshing", to explain
what happens to the energy in a transmission line with reflections.
--
73, Cecil http://www.qsl.net/w5dxp

Cecil wrote:
This is just one more example of the dumbing down of amateur radio
accompanying the dumbing down of the US educational system in
general. Unfortunately, it seems to be a trend that cannot be
reversed because it is the biased view being pushed by the ARRL
and its supporters.

Hmmm...not sure I agree that the folks at ARRL are deliberately being
dumb (or maybe I just misunderstood you). Seems more unintentional to
me. After all, the technical editor of QEX let publish that bizarre
article that claimed to prove by math that phasing SSB receivers were
not possible. Can''t imagine a political motivation for that though I
have to wonder bigtime how that one got by. QEX really really needs
for some good peer review.

Ah, to have Ham Radio magazine back again. Loved that thing. Learned
most of my radio from it.

73,
Glenn AC7ZN

wrote in message
oups.com...
Cecil wrote:
This is just one more example of the dumbing down of amateur radio
accompanying the dumbing down of the US educational system in
general. Unfortunately, it seems to be a trend that cannot be
reversed because it is the biased view being pushed by the ARRL
and its supporters.

Hmmm...not sure I agree that the folks at ARRL are deliberately being
dumb (or maybe I just misunderstood you). Seems more unintentional to
me. After all, the technical editor of QEX let publish that bizarre
article that claimed to prove by math that phasing SSB receivers were
not possible. Can''t imagine a political motivation for that though I
have to wonder bigtime how that one got by. QEX really really needs
for some good peer review.


I don't think anyone is trying to be "deliberately being dumb", more like
"naturally being dumb" and not knowing it. :-)
Reality is that quality of technical material in ham publications is
slipping, heading for stuck on stupid. Add cheapening of ham ticket exams,
push for mass and no exam recruiting of new hams (a la CB wizards) in effort
to boost numbers and few bad apples with it - you get the picture of
deteriorating standards.

When W8JI had a presentation at Dayton's Antenna Forum and spoke about his
"famous - same current along the antenna loading coil", I came to K3LR
(forum leader) and N6BV (ARRL Antenna Book editor) and pointed out that
perhaps there is an error in W8JI assertions, I got this in private mail
from the "guru":

"When you pull people aside at Dayton to bitch about me or others or make
wild crazy statements it just makes you look worse and worse to the people
you are trying most to impress. At Dayton two years ago several people came
up and told me your tried to start conversations about me with them, or that
you started bitching about me."

Sooo, looks like one has to take some articles in ARRL publications with
biiiig grain of salt. Goofy stuff gets through, real expert material gets
swept under by "know-it-alls" in charge, Goofy is right and Right is not
important anymore. "Gurus" beat their drums into the publications and great
confusion ensues.

As far as SWR, I always tried to avoid it by matching, designing antennas to
have impedance of the feedline, and the TX/Amp output matching the feedline
impedance. Standing Wave Ratio always implied two waves - forward and
reflected and their superposition. Why waste power in "confused" standing
waves, when I can make sure that the waves are marching forward towards the
antenna and be radiated. Let the waves stand in the antenna, where they
belong, doing radiating and not in the lossy feedline.
High SWR is not imaginary, it is real, can create excessive voltages,
dielectric losses and melt the coax.

Happy Mother's Day to all the mothers that did not abort us!
God Bless them and thank you!

Yuri, da BUm

Yuri Blanarovich wrote:
When W8JI had a presentation at Dayton's Antenna Forum and spoke about his
"famous - same current along the antenna loading coil", ...

It is unusual for W8JI to give up on an argument so abruptly. I
wish I had thought of the dual-Z0 shortened stub concept years ago.
--
73, Cecil http://www.qsl.net/w5dxp

wrote:
Hmmm...not sure I agree that the folks at ARRL are deliberately being
dumb (or maybe I just misunderstood you).

Let me just relate my personal experience. I submitted an article
to QEX which mentioned light wave theory as explained in "Optics",
by Hecht. An (un-named) QEX employee, with whom I was dealing, had
"Optics" as a college textbook and was very interested in the subject.
He suggested that I expand the light wave theory section of my article,
which I did. After about four revisions, he suddenly stopped responding
to my emails. A couple of months later, I received a rejection letter.
That was well over a year ago.

Two QEX articles have recently appeared covering exactly the same
material as my article but with different slants. QEX still will
not answer my emails and will not publish my letters to the editor.
My treatment by QEX is more akin to religious shunning than
anything else.

I am convinced that the QEX employee that I was dealing with is
deliberately publishing dumbed-down material because he previously
indicated that he knows different from his college optics course.
He is most probably being directed to do so by his superiors because
he was, at first, enthusiastic about publishing my article which
is available from my web page below.
--
73, Cecil http://www.qsl.net/w5dxp/energy.htm

Cecil Moore wrote:
Gene Fuller wrote:

Why would anyone try to prove that the basic math of adding sinusoidal
functions is incorrect? To the contrary, you are the one who insists
that a standing wave and its constituent traveling wave components are
somehow different and unique.


Actually, it was you who made that assertion and thanks for the
opportunity to quote you once again:

Gene Fuller, W4SZ wrote:
In a standing wave antenna problem, such as the one you describe,
there is no remaining phase information. Any specific phase
characteristics of the traveling waves died out when the startup
transients died out.

So standing waves are "somehow different" from traveling waves
according to your own assertions. The traveling wave possesses
phase characteristics and the standing wave doesn't.


Cecil,

You keep making the same mistake. Yes, you can analyze traveling waves
instead of standing waves if you so choose. However, there is not one
bit of additional physical information in the traveling waves that is
not in the standing wave. Any "phase characteristic" is simply a
function of the mathematical manipulations you use.

Perhaps someday you will actually understand superposition, but I won't
hold my breath.

73,
Gene
W4SZ

Gene Fuller wrote:
However, there is not one
bit of additional physical information in the traveling waves that is
not in the standing wave.

I agree with you but W8JI and W7EL have rejected the concept that
there is any phase information in the standing wave current magnitude.
They have rejected any use of the arc-cosine function in calculating
that phase. The following graphs show the difference in the standing
wave current and the traveling wave current.

http://www.qsl.net/w5dxp/travstnd.GIF

The standing wave current phase contains zero phase information
as you have stated. As you say, all the standing wave current
phase information is contained in the magnitude but the arc-cosine
function for obtaining that phase information has been rejected by
the experts. For the traveling wave, there is phase information
contained in the phase, none in the magnitude.

Every time you make a technical assertion, you support my argument.
Seems your argument is really with the side that rejects the arc-
cosine function for obtaining phase information.
--
73, Cecil http://www.qsl.net/w5dxp