Cecil Moore wrote:
Gene Fuller wrote:

I do not disagree with anything you have said.


Please answer this question. Does the amplitude of the
standing wave current contain any phase information?

You have previously asserted that it does. Roy says
it doesn't. Time to chose between technical fact
and agreeing with your friend (who is technically
incorrect).

Cecil,

You win!

You have now set the new world record in misquoting. You might want to
give a call to the fine folks at Guinness.

73,
Gene
W4SZ

wrote:
It looks like Dave successfully excited some natural frequencies in the
group for some weekend entertainment. Congratulations.

I don't see how there can be any argument. The standing wave
current envelope magnitude pattern pictured in Kraus is a cosine
function where the angle of the cosine function is the number of
degrees away from the feedpoint. If the feedpoint current is 1.0
amps at 0 degrees, the standing wave current magnitude in Kraus'
1/2WL thin-wire dipole has the following pattern.

degrees away
from feedpoint current magnitude
0 1.000 amps
30 0.866 amps
45 0.707 amps
60 0.500 amps
90 0.000 amps

How can anyone defend an argument asserting that standing wave
current magnitude contains no phase angle information? The arc-
cosine of the standing wave current magnitude above *IS* the
number of degrees of phase angle away from the feedpoint. Since
the antenna is an archetypical standing wave antenna, that phase
angle is also the absolute magnitude of the forward and reflected
current phase angles where those phase angles have opposite signs.
--
73, Cecil http://www.qsl.net/w5dxp

Tom Donaly wrote:
If all you have is the value of current at one point,
you can't possibly tell anything about the phase.

But the value of current at one point is *NOT* all we have
so your supposition is irrelevant. After a century of theory
by some of the most brilliant human minds, we know virtually
everything there is to know about a 1/2WL thin-wire dipole.
We know there *IS* indeed phase information in the standing
wave current magnitude just Kraus graphed it in his book.

You need
to compare it to something - itself even - somewhere or sometime else in
order to have an idea of phase.

The standard thing to compare it to is the feedpoint current,
e.g. provided by EZNEC, usually 1.0 amps at 0 degrees.

Here's what I mean: suppose I have a
piece of wire of unknown length, excited by an unknown frequency, and
picking a random point on the wire I measure 1.73 amps. What is the
phase? You're trying to square the circle and hear the sound of one
hand clapping at one and the same time, Cecil.

First, you insult me with irrelevant ad hominem attacks ...

Of course, in your
case, you know the length of the wire, the frequency of the wave and
its wavelength, and you think you know the current distribution
on the wire (a half wavelength dipole) so you don't need anything
but a ruler to find what you're looking for.

And second, you agree with Kraus and me ...

Here is a chart regarding Kraus' 1/2WL thin-wire dipole copied from
my other posting. Please tell us what is wrong with it and exactly
why the standing wave current magnitude doesn't tell us how many
degrees away the feedpoint is for the formula I = Io*cos(X).

X degrees away standing wave arc-cosine of the
from feedpoint current magnitude current magnitude
0 1.000 amps 0 deg
30 0.866 amps 30 deg
45 0.707 amps 45 deg
60 0.500 amps 60 deg
90 0.000 amps 90 deg

Do you really think it is a mere coincidence that column 1 and
column 3 are identical???
--
73, Cecil http://www.qsl.net/w5dxp

Tom Donaly wrote:
For someone like me, Cecil can be (but usually isn't) a very useful
crackpot. I can be pretty sure he's wrong, but the process of educating
myself into turning that hunch into a dead certainty that I can prove
to everyone (except him) can be enlightening.

Now's your chance to enlighten us, Tom. Please explain again
how the standing wave current magnitude on a 1/2WL thin-wire
dipole doesn't depend upon how many degrees it is away from
the feed point, i.e. doesn't contain any phase information.

While you are at it, please explain exactly how Kraus is mistaken
about this antenna when he plots the standing wave current as
I = cos(X) where X is the number of degrees away from the
feedpoint and feedpoint current equals 1 amp at 0 degrees.
--
73, Cecil http://www.qsl.net/w5dxp

Gene Fuller wrote:

Cecil Moore wrote:
Please answer this question. Does the amplitude of the
standing wave current contain any phase information?

You have previously asserted that it does. Roy says
it doesn't. Time to chose between technical fact
and agreeing with your friend (who is technically
incorrect).

Cecil, You win!
You have now set the new world record in misquoting. You might want to
give a call to the fine folks at Guinness.

It was a simple yes/no question, Gene. That you refuse to
answer speaks volumes so I will ask it once again, copying
from a previous posting that you ignored.

Just insert an 'X' for the one you agree with. If you don't
respond, I will add this to a long list of questions that
I have asked that the "experts" are afraid to answer.

_____ Standing wave current magnitude contains some phase
information.

_____ Standing wave current magnitude contains zero phase
information.
--
73, Cecil http://www.qsl.net/w5dxp

Cecil Moore wrote:
Tom Donaly wrote:

If all you have is the value of current at one point,
you can't possibly tell anything about the phase.


But the value of current at one point is *NOT* all we have
so your supposition is irrelevant. After a century of theory
by some of the most brilliant human minds, we know virtually
everything there is to know about a 1/2WL thin-wire dipole.
We know there *IS* indeed phase information in the standing
wave current magnitude just Kraus graphed it in his book.

You need
to compare it to something - itself even - somewhere or sometime else
in order to have an idea of phase.


The standard thing to compare it to is the feedpoint current,
e.g. provided by EZNEC, usually 1.0 amps at 0 degrees.

Here's what I mean: suppose I have a
piece of wire of unknown length, excited by an unknown frequency, and
picking a random point on the wire I measure 1.73 amps. What is the
phase? You're trying to square the circle and hear the sound of one
hand clapping at one and the same time, Cecil.


First, you insult me with irrelevant ad hominem attacks ...

Of course, in your
case, you know the length of the wire, the frequency of the wave and
its wavelength, and you think you know the current distribution
on the wire (a half wavelength dipole) so you don't need anything
but a ruler to find what you're looking for.


And second, you agree with Kraus and me ...

Here is a chart regarding Kraus' 1/2WL thin-wire dipole copied from
my other posting. Please tell us what is wrong with it and exactly
why the standing wave current magnitude doesn't tell us how many
degrees away the feedpoint is for the formula I = Io*cos(X).

X degrees away standing wave arc-cosine of the
from feedpoint current magnitude current magnitude
0 1.000 amps 0 deg
30 0.866 amps 30 deg
45 0.707 amps 45 deg
60 0.500 amps 60 deg
90 0.000 amps 90 deg

Do you really think it is a mere coincidence that column 1 and
column 3 are identical???

Cecil, you can always know something you already know. Knowing that your
antenna is 1/2 wavelength long gives you all the information you need
for your definition of phase. By the way, where did you get that table,
from EZNEC?
73,
Tom Donaly, KA6RUH

Cecil Moore wrote:

Tom Donaly wrote:

For someone like me, Cecil can be (but usually isn't) a very useful
crackpot. I can be pretty sure he's wrong, but the process of educating
myself into turning that hunch into a dead certainty that I can prove
to everyone (except him) can be enlightening.


Now's your chance to enlighten us, Tom. Please explain again
how the standing wave current magnitude on a 1/2WL thin-wire
dipole doesn't depend upon how many degrees it is away from
the feed point, i.e. doesn't contain any phase information.

While you are at it, please explain exactly how Kraus is mistaken
about this antenna when he plots the standing wave current as
I = cos(X) where X is the number of degrees away from the
feedpoint and feedpoint current equals 1 amp at 0 degrees.

I didn't say that the value of the standing wave current on a
1/2 wavelength dipole doesn't vary with length. I did say that
just measuring the value at some point doesn't give you all the
information you need to calculate the phase. Of course, you already
know the phase, because you defined the antenna as 1/2
wavelength, so finding any kl is trivial. Secondly, even if you're
right about the current in your antenna being a sine function, in order
to use that information, you have to measure the current input at the
current maximum - which you've already defined to be the center of the
antenna - in order to compare it with the current at the point of
interest in order to get your result. In short, you still have to
know the current at two points in order to get an answer. The
information isn't contained in just one measurement. So let me turn it
around and ask you to tell me again why you think you can get some
"phase" information from measuring a single point on an antenna
without knowing anything else about it.

I haven't read Kraus, but I expect he was talking about an idealized,
infinitely thin antenna. Add thickness to the wire, and a feedpoint gap,
and you may come up with something slightly more complicated.
73,
Tom Donaly, KA6RUH

Cecil Moore wrote:

Gene Fuller wrote:

Cecil Moore wrote:

Please answer this question. Does the amplitude of the
standing wave current contain any phase information?

You have previously asserted that it does. Roy says
it doesn't. Time to chose between technical fact
and agreeing with your friend (who is technically
incorrect).


Cecil, You win!
You have now set the new world record in misquoting. You might want to
give a call to the fine folks at Guinness.


It was a simple yes/no question, Gene. That you refuse to
answer speaks volumes so I will ask it once again, copying
from a previous posting that you ignored.

Just insert an 'X' for the one you agree with. If you don't
respond, I will add this to a long list of questions that
I have asked that the "experts" are afraid to answer.

_____ Standing wave current magnitude contains some phase
information.

_____ Standing wave current magnitude contains zero phase
information.

If a magnitude can, by itself, contain phase information, why
do we have to specify the angle in a phasor?
73,
Tom Donaly, KA6RUH

Tom Donaly wrote:
Cecil, you can always know something you already know. Knowing that your
antenna is 1/2 wavelength long gives you all the information you need
for your definition of phase.

Apparently that knowledge is not enough for W7EL who said
regarding the current distribution in a 1/2WL thin-wire
dipole:

W7EL wrote:
Of course I reject the notion that there's "phase information
in the standing wave current magnitude".

This in the face of technical evidence that the standing
wave current magnitude is a cosine function of the number
of degrees the referenced point is away from the feedpoint.

Also contradicting Gene Fuller who said:
The only "phase" remaining is the cos (kz) term, which is really
an amplitude description, not a phase.

By the way, where did you get that table, from EZNEC?

From page 464 of "Antennas for all Applications", 3rd Edition,
by Kraus and Marhefka. Where Kraus presents the independent
variable in fractions of a wavelength, I simply converted it
to degrees. Most knowledgeable people comprehend that there
are 360 degrees per sinusoidal cycle, i.e. per one wavelength.
--
73, Cecil http://www.qsl.net/w5dxp

On Mon, 15 May 2006 17:12:58 GMT, "Tom Donaly"
wrote:

_____ Standing wave current magnitude contains some phase
information.

_____ Standing wave current magnitude contains zero phase
information.

If a magnitude can, by itself, contain phase information, why
do we have to specify the angle in a phasor?


Hi Tom,

Cecil probably doesn't understand that both options give both current
magnitude AND phase as choices. Rather makes the "question"
pointless, but nothing new in the correspondence from our Xerox
philosopher.

For the record:

____X____ Standing wave current magnitude contains NO phase
information.

73's
Richard Clark, KB7QHC