Cecil Moore wrote:
Tom Donaly wrote:

current, in a wire, is the total current density integrated across
a cross section of the wire. It's a vector, ...


From "Fields and Waves in Communications Electronics", by Ramo, Whinnery,
& Van Duzer, page 239: "It must be recognized that the symbols in the
equations of this article have a *different* meaning from the same symbols
used in Art. 4.06. There they represented the instantaneous values of the
indicated *vector* and scalar quantities. Here they represent the complex
multipliers of e^jwt, giving the in-phase and out-of-phase parts with
respect to the chosen reference. The complex scalar quantities are commonly
referred to as *phasors*, ..."

From the IEEE Dictionary: "The phase angle of a phasor should not be
confused with the space angle of a vector."

You are obviously confusing vectors and phasors.
--
73, Cecil http://www.qsl.net/w5dxp


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You're just digging the hole deeper, Cecil. I know you think you can use
the simplifications of transmission line theory to explain everything
in electromagnetics. Reg seems to think that's a valid way of doing
things, too. If it were true, it would certainly make life easier for
those poor souls who have to study Maxwell's equations in colleges
throughout the world. Just think, no more vector calculus for engineers!
From what I've read on this group the past few days, many engineers
don't learn it anyway, so why not just dumb things down to
your level? Maybe you should write a letter to Texas A&M telling them
they don't have to teach it any more. (If they still do, that is. Some
colleges have dumbed themselves down considerably in the past 20 years.)
73,
Tom Donaly, KA6RUH

Richard Clark wrote:
Cecil Moore wrote:
behavior of the antenna is irrelevant

sour grapes :-)

Yes, from you guys. "OK, I admit I was wrong, but that original
argument didn't matter anyway." :-)


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Tom Donaly wrote:
You're just digging the hole deeper, Cecil. I know you think you can use
the simplifications of transmission line theory to explain everything
in electromagnetics.

The transmission line model is more complicated than the circuit
model and works for transmission lines, including antennas, which
are single-wire transmission lines. Your overly simplified circuit
model doesn't work for transmission lines or for antennas. That's
what got you (and others) into trouble. All you guys can do now
to try to save face is sandbag and divert the issue.
--
73, Cecil http://www.qsl.net/w5dxp


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Tom Donaly wrote:
"I know you think you can use the simplification of transmission line
theory to explain everything in electromagnetics. Reg seems to think
that`s a valid way of doing things, too."

I had a graduate course in Maxwell`s equations, but had a long rewarding
career without using Maxwell directly.

Reg is an advocate of Oliver Heaviside`s work based on Maxwell. Nothing
wrong with that.

In his 1950 work "Antennas", Kraus has this to say about Maxwell`s
equations:

"Maxwell`s equations are summarized in the tables. The first table gives
Maxwell`s equations in differential form and the second table in
intergral form. The equations are stated for the general case,
free-space case, harmonic-variation case, steady case (static fields but
with conduction currents), and static case (static fields with no
currents). In the table giving the integral form, the equivalence is
also indicated between the various equations and the electrical
potential or emf, the magnetic potential or mmf, the electric current,
the electric flux, and then magnetic flux.

Many texts do very well with no mention of Maxwell despite his
contributions to electromagnetics. That`s too bad, but that`s the way it
is.

Best regards, Richard Harrison, KB5WZI

Tom Donaly wrote:
Jim Kelley wrote:
Not sure why you don't like gradients, Tom. I'm sure Mr. Cheng is
undoubtedly correct, but I'm just as sure he didn't intend that
sentence as any sort of definition of the term "gradient".


Actually, he did. It's the accepted definition of the term in
electromagnetics. You and Cecil are using the term in a more
general fashion which you've made up for the purpose. It doesn't
make much sense in an elecromagnetic setting. Similarly, Yuri,
Richard and Cecil made up a very loose term "current drop" for
a change in current at two ends of a coil. That was misleading
and wrong if they were trying to convey something about the
electromagnetics of a coil, which they were. I've seen you fellows
pick each other to death over trivia time and again. It's time
you paid attention to what you write.

That's something you

have apparently read into it. The gradient in our case (since you
proposed the question) would be expressed as the superposition of
forward and reverse currents, with magnitude and phase (or direction
if you prefer) written as a function of either position or angle
*along* the radiator. It's nothing fancy. Honest. It's simply the
rate of change of current as a function of position. The gradient
across the radiator at any given point along the radiator could then
be determined using some additional parameters - if someone were
really that interested in it (which I'm not).

73, ac6xg


How could the gradient be in your case if I proposed the
question?
73,
Tom Donaly, KA6RUH

Are you trying to make some point? If so, I'd sure like to know what it
is. It appears you're trying to pretend that the gradient (a
mathematical term) in the standing wave current along the length of a
radiator doesn't exist. Why? It's a very simple and straightforward
notion.

73, Jim AC6XG

Jim Kelley wrote:


Tom Donaly wrote:

Jim Kelley wrote:

Not sure why you don't like gradients, Tom. I'm sure Mr. Cheng is
undoubtedly correct, but I'm just as sure he didn't intend that
sentence as any sort of definition of the term "gradient".



Actually, he did. It's the accepted definition of the term in
electromagnetics. You and Cecil are using the term in a more
general fashion which you've made up for the purpose. It doesn't
make much sense in an elecromagnetic setting. Similarly, Yuri,
Richard and Cecil made up a very loose term "current drop" for
a change in current at two ends of a coil. That was misleading
and wrong if they were trying to convey something about the
electromagnetics of a coil, which they were. I've seen you fellows
pick each other to death over trivia time and again. It's time
you paid attention to what you write.

That's something you

have apparently read into it. The gradient in our case (since you
proposed the question) would be expressed as the superposition of
forward and reverse currents, with magnitude and phase (or direction
if you prefer) written as a function of either position or angle
*along* the radiator. It's nothing fancy. Honest. It's simply the
rate of change of current as a function of position. The gradient
across the radiator at any given point along the radiator could then
be determined using some additional parameters - if someone were
really that interested in it (which I'm not).

73, ac6xg


How could the gradient be in your case if I proposed the
question?
73,
Tom Donaly, KA6RUH


Are you trying to make some point? If so, I'd sure like to know what it
is. It appears you're trying to pretend that the gradient (a
mathematical term) in the standing wave current along the length of a
radiator doesn't exist. Why? It's a very simple and straightforward
notion.

73, Jim AC6XG


Keep trying, Jim.
73,
Tom Donaly, KA6RUH

Cecil Moore wrote:

Tom Donaly wrote:

You're just digging the hole deeper, Cecil. I know you think you can use
the simplifications of transmission line theory to explain everything
in electromagnetics.


The transmission line model is more complicated than the circuit
model and works for transmission lines, including antennas, which
are single-wire transmission lines. Your overly simplified circuit
model doesn't work for transmission lines or for antennas. That's
what got you (and others) into trouble. All you guys can do now
to try to save face is sandbag and divert the issue.
--
73, Cecil http://www.qsl.net/w5dxp


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Who said anything about a circuit model?
73,
Tom Donaly, KA6RUH

Tom Donaly wrote:

Jim Kelley wrote:

Keep trying, Jim.
73,
Tom Donaly, KA6RUH

To what end? It's not a controversial issue.

73, Jim AC6XG

Tom Donaly wrote:
Who said anything about a circuit model?

I'm going to present an example, step by step. Please contribute
something technical in response.

It's a simple lossless quarter-wave matching section example.

------50 ohm feedline---+---1/4WL 600 ohm feedline---7200 ohm load
Pfor1=100w-- Pfor2=352w-- 100w
--Pref1=0w --Pref2=252w
Vfor1=70.7v-- Vfor2=460v-- Vload=849v
--Vref1=0v --Vref2=389v
Ifor1=1.414A-- Ifor2=0.766A-- Iload=0.118A
--Iref1=0A --Iref2=0.648A

Vref2 is 180 degrees out of phase with Vfor2 and thus they subtract.

Iref2 is in phase with Ifor2 and thus they add.

The impedance at '+' is (Vfor2-Vref2)/(Ifor2+Ifor1)

The impedance at '+' is (460v-389v)/(0.766A+0.648A) = 70.7V/1.414A = 50 ohms

Note that the impedance seen at the match point is:

Vfor1/Ifor1 = (Vfor2-Vref2)/(Ifor2+Iref2)

So Tom, do you find anything wrong with this network analysis? If so,
please be technically specific. (Sorry, your feelings don't matter.)
--
73, Cecil http://www.qsl.net/w5dxp


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Cecil Moore wrote:
Tom Donaly wrote:

Who said anything about a circuit model?


I'm going to present an example, step by step. Please contribute
something technical in response.

It's a simple lossless quarter-wave matching section example.

------50 ohm feedline---+---1/4WL 600 ohm feedline---7200 ohm load
Pfor1=100w-- Pfor2=352w-- 100w
--Pref1=0w --Pref2=252w
Vfor1=70.7v-- Vfor2=460v-- Vload=849v
--Vref1=0v --Vref2=389v
Ifor1=1.414A-- Ifor2=0.766A-- Iload=0.118A
--Iref1=0A --Iref2=0.648A

Vref2 is 180 degrees out of phase with Vfor2 and thus they subtract.

Iref2 is in phase with Ifor2 and thus they add.

The impedance at '+' is (Vfor2-Vref2)/(Ifor2+Ifor1)

The impedance at '+' is (460v-389v)/(0.766A+0.648A) = 70.7V/1.414A = 50
ohms

Note that the impedance seen at the match point is:

Vfor1/Ifor1 = (Vfor2-Vref2)/(Ifor2+Iref2)

So Tom, do you find anything wrong with this network analysis? If so,
please be technically specific. (Sorry, your feelings don't matter.)
--
73, Cecil http://www.qsl.net/w5dxp


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Cecil, if I had a dollar for every time you challenged someone to solve
a quarter wavelength transmission line transformer problem I could eat a
meal in the best restaurant in San Francisco and still have change left
over to pay a 20% tip. The question is not whether or not the theory
you made up in your head is right or not, but whether the length, shape,
volume, whatever of a loading coil on a short antenna makes any
substantial difference in the efficiency of the antenna. The problem of
increasing the total current on a short antenna was solved so many years
ago the fellows who solved it are old enough to be Richard Harrison's
grandparents. If Yuri would spend more time researching his subject and
less time with his fish thermometers and his diatribes against Tom Rauch
he would learn that.
73,
Tom Donaly, KA6RUH