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On Sat, 20 May 2006 17:39:44 GMT, "Tom Donaly"
wrote:

Cecil thinks your simplified ideas are received wisdom.

Hi Tom,

Is there some suggestion of smoldering bush in this parable?
Commandments that are unzipped and ready for immediate entablature?

73's
Richard Clark, KB7QHC

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Cecil Moore wrote:

Reg Edwards wrote:

I suppose, Cecil,
that if you keep repeating the same old tired line, over and over
again, you might find someone who will agree with you.


I agreed with Cecil the first time he said it.
But I'm only a foreigner.
So whatever I say doesn't carry any weight.
Or does it?


I dug out my linear network theory book and would like
to present a few quotes and comments:

"The real world is inherently non-linear."

Lightning hitting an antenna can cause arcing and melted
wires.

"Although nature is non-linear, linear approximations over
defined ranges of validity are valid representations of
non-linear phenomena."

Amateur radio antennas are usually confined to that limited
linear range.

"The necessary and sufficient conditions for a linear system
a (1) validity of the principle of superposition;
(2) preservation of scale factor.

Does doubling the power input to the antenna ~double the
radiated power? Does it ~double the non-radiated losses?

"Fortunately for the engineer, however, linear systems are
frequently excellent approximations to reality and have a
wide range of validity in the real world."

Maxwell's equations in particular. Textbook equations for
traveling waves and standing waves assume linearity.

You can still pretend a dipole is a "linear system," as you
call it, and still understand that the current envelope is not
a simple sine function. The Achilles heel of all your reflection
mechanics ideas is the assumption that everything is lossless.
(Not to mention the fact that it's supposed to exist in outer
space.) You and Reg like to think of a dipole as a transmission line,
and Reg can even tell you its characteristic impedance (average). What
neither he nor you ever mention is the alpha part of the
propagation constant. That's the important part, though, since it
signifies radiation, the very thing the antenna was designed to do.

By the way, why are you quoting from a network theory book when not
too long ago you were ranting and raving about the invalidity of the
lumped constant model?
73,
Tom Donaly, KA6RUH

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"Richard Clark" wrote in message
...
On Sat, 20 May 2006 12:14:29 -0000, "Dave" wrote:

KEEP IT GOING!

Dave, your trolling effort is rather a poor substitute for the sense
of accomplishment. Too many do it far better, with more flair, and
offer more entertainment than this pallid use of the CAPS KEYS.

I'm just cheering you on... besides if I'm going to troll I might as well
abandon some other parts of decency in the process. And it doesn't seem
like anyone cares, even with the obvious thread title it took off all on its
own.

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Tom Donaly wrote:
You can still pretend a dipole is a "linear system," as you
call it, and still understand that the current envelope is not
a simple sine function.

Diverting to a "simple" sine function in the same spirit as
diverting to a "small" loading coil?

If you were always talking about a perfect sine wave, you should
have said so long before now and nobody would have disagreed with
you.

The Achilles heel of all your reflection
mechanics ideas is the assumption that everything is lossless.

That's NOT the assumption. The assumption is that lossless systems
are easiest to understand so let's understand them first before
we move on to something more complex. You guys have proven that
you don't even understand the simple lossless condition.

(Not to mention the fact that it's supposed to exist in outer
space.) You and Reg like to think of a dipole as a transmission line,
and Reg can even tell you its characteristic impedance (average). What
neither he nor you ever mention is the alpha part of the
propagation constant. That's the important part, though, since it
signifies radiation, the very thing the antenna was designed to do.

Only about 1 dB of the steady-state energy stored in a 1/2WL
dipole is radiated so radiation is not the largest effect. The
radiation from an antenna can be simulated by using resistance
wire to simulate a 1 dB loss in a transmission line. The reason
that I have rarely mentioned such is that you guys don't understand
enough of the basics to proceed to those more complex examples.

By the way, why are you quoting from a network theory book when not
too long ago you were ranting and raving about the invalidity of the
lumped constant model?

The lumped constant model is valid under certain conditions. What I
object to is its use under known invalid conditions. The lumped constant
model and distributed network model are both *linear systems*.
--
73, Cecil http://www.qsl.net/w5dxp

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Richard Clark wrote:
On Sat, 20 May 2006 17:39:44 GMT, "Tom Donaly"
wrote:


Cecil thinks your simplified ideas are received wisdom.


Hi Tom,

Is there some suggestion of smoldering bush in this parable?
Commandments that are unzipped and ready for immediate entablature?

73's
Richard Clark, KB7QHC

Hi Richard,
Yes, but there's some evidence Cecil is about to
apostatize. I hope he doesn't end up wandering in the wilderness.
73,
Tom Donaly, KA6RUH

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Richard Harrison wrote:
Richard Clark, KB7QHC wrote:
"Who. in your estimation, does qualify to discuss it?"

If it`s about antennas, I nominate Kraus. If it`s about mathematics,
many marhematicians qualify.

In algebra, y = mx + b, (the point slope formula), is called linear
because it is the graph of a straight line.
. . .

But of course you realize that the function y = mx + b doesn't meet the
requirements of a linear function when applied to network theory.

Roy Lewallen, W7EL

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Richard Harrison wrote:
Cecil, W5DXP wrote:
"Assuming the source signal is a pure sine wave, if the standing wave
current "isn`t in general sinusoidally shaped (as Roy said)", then the
antenna would have to be introducing harmonic radiation that doesn`t
exist in the source signal."
. . .

Either Cecil is misquoting me, or Richard is misquoting Cecil.

Cecil calls the total current the "standing wave current". I never said
that the standing wave current isn't sinusoidally shaped. I said that
the *envelope* of the standing wave -- that is, a graph of the magnitude
of the current on a transmission line as a function of position along
the line -- is not sinusoidally shaped except in the special case of a
complete reflection. This isn't a personal theory, but a very well
established fact which can easily be derived from fundamental equations.
(Or it can even be found clearly stated in texts for those unable to
understand the derivation.) On antennas, the current distribution
(magnitude of current vs position) is generally not sinusoidal either,
although it's approximately so on thin wire antennas.

Assuming that the transmission line is driven with a pure sine wave, the
forward, reverse, and total currents as a function of *time* will be
sinusoidal and consequently no harmonics will be generated. (I'm of
course neglecting nonlinear effects which might occur in a real
transmission line or antenna such as magnetic conductors or nonlinear
dielectrics. But in practical terms these will be virtually unmeasurable
with ordinary coax or twinlead and amateur power levels.)

It's hard to determine whether Cecil's sustained confusion between a
time waveform and a graph of amplitude vs distance is intentional or if
the concepts are really mixed up for him. It has, in either case,
provided a convenient diversion from his basic strange theories at the
time it was getting particularly hard for him to continue supporting them.

Roy Lewallen, W7EL

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Roy Lewallen wrote:
Richard Harrison wrote:
In algebra, y = mx + b, (the point slope formula), is called linear
because it is the graph of a straight line.

But of course you realize that the function y = mx + b doesn't meet the
requirements of a linear function when applied to network theory.

I knew what Richard meant. Quoting "Linear Network Theory",
by Ferris: "In the functional relationship, h(t)=kf(t), no
matter what h(t) and f(t) represent, the relation h(t)=kf(t)
must be linear. ... An elementary concept, then, is that h(t)
and f(t) are related by a straight line of the form
h(t) = mt + b."
--
73, Cecil http://www.qsl.net/w5dxp

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Roy Lewallen wrote:

Richard Harrison wrote:

Cecil, W5DXP wrote:
"Assuming the source signal is a pure sine wave, if the standing wave
current "isn`t in general sinusoidally shaped (as Roy said)", then the
antenna would have to be introducing harmonic radiation that doesn`t
exist in the source signal."

Either Cecil is misquoting me, or Richard is misquoting Cecil.

Richard quoted me correctly. I did *NOT* quote you. I merely
stated what I thought you said.

Cecil calls the total current the "standing wave current".

That is absolutely false. Total current equals standing wave
current plus traveling wave current. Or standing wave current
equals total current minus traveling wave current. Subtract
out the traveling wave component and a pure standing wave
component is left.

Note that you did not quote me. You merely stated what you
thought I said and you were mistaken.

I never said
that the standing wave current isn't sinusoidally shaped. I said that
the *envelope* of the standing wave -- that is, a graph of the magnitude
of the current on a transmission line as a function of position along
the line -- is not sinusoidally shaped except in the special case of a
complete reflection.

The envelope of the standing wave current is the same whether
reflection is complete or not since the traveling wave current
has been subtracted from the total current.

Seems you should have said the total current envelope is not
sinusoidal. The standing wave current envelope is obviously
sinusoidal since the traveling wave has been subtracted.

This isn't a personal theory, but a very well
established fact which can easily be derived from fundamental equations.

Please provide a reference that says after the traveling wave
current has been subtracted from the total current, the resulting
standing wave current envelope is not sinusoidal.

(Or it can even be found clearly stated in texts for those unable to
understand the derivation.) On antennas, the current distribution
(magnitude of current vs position) is generally not sinusoidal either,
although it's approximately so on thin wire antennas.

Just because the scale of the position axis changes with VF doesn't
mean things become non-sinusoidal.

Assuming that the transmission line is driven with a pure sine wave, the
forward, reverse, and total currents as a function of *time* will be
sinusoidal and consequently no harmonics will be generated.

This statement contradicts what I thought you said before. Seems
we are now in agreement.
--
73, Cecil http://www.qsl.net/w5dxp

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Roy Lewallen, W7EL wrote:
"But of course you realize that the function y = mx + b doesn`t meet the
requirements of a linear function when applied to network theory."

Works for me.

Linear means the graph of the function is a straight line.

f(x) = y = mx + b is called linear because its graph is a straight line.

A straight line is the shortest distance between two points.

In y = mx + b, m is a constant determining the slope of the line. x is
is the independent variable. b is the offset or point along the x-axis
where the line crosses.

y then is a linear function of x because its slope is always mx, but
displaced in the x-direction by a constant value, namely b.

y is linear the same as IR is linear, or by substitution, E is linear in
Ohm`s law where E=IR. For any value of I, voltage = IR and the graph of
I versus E is a straight line with a slope equal to R.

Resistance is a common factor in network theory.

Best regards, Richard Harrison, KB5WZI