Ian White GM3SEK wrote:
I don't intend to - that quotation is perfectly correct. It means that
in a test-case situation where the lumped model *does* apply, the
distributed model will give EXACTLY the same results.

Ian, you know nothing is "EXACTLY" the same. All you can say is that
the two models give acceptably similar results within a certain range
of accuracy.

To paraphrase Roger Whittaker: "'EXACTLY' is for Children Spinning
Daydreams".

This is the test case that I'm trying to make you apply, to check that
with a lumped-inductance load, your antenna theory predicts the correct
behaviour, namely no phase shift in the current through a lumped
inductance.

:-) That's like proving there's no loss in a lossless transmission
line, Ian. Please send me a 100 uH lumped inductance and I will
run some tests on it and report back to you. What do you want to
bet the lumped circuit model will be wrong?

Some people have a problem with their model trying to dictate reality.
You seem to have fallen into that trap. Allow me to raise my voice.

THERE IS NO SUCH THING IN REALITY AS A LUMPED INDUCTANCE!!!!

The lumped circuit model is an approximation to reality. It has
been patched numerous times as situations came up that it could
not handle. Sometimes it works and sometimes it doesn't work.
Since the distributed network model is a superset of the lumped
circuit model, if there is ever any disagreement between the two
models, the distributed network model wins every time.

The test is not whether the distributed network model yields the
same results as the lumped circuit model. The test is whether
the lumped circuit model yields the same results as the
distributed network mode. That's what the argument is all about.
The distributed network model is the GOLD standard. The lumped
circuit model is just a pale approximation to reality.

There's no problem with the distributed circuit model. There's no
problem with the lumped circuit model as a subset of that. All the
problems are with your incorrect application of those models.

That may be true, but we will never know until you (and others)
recognize the difference between standing wave current and
traveling wave current as explained in my other posting. But
in case you missed it, here is a one wavelength dipole fed 1/4
WL from the right end. ///// is a 90 degree loading coil.

------A------B-/////-D-------------fp-------------

The current at B is measured by an RF ammeter at one amp. The
current at D is measured by a similar RF ammeter at zero amps.
I can provide an EZNEC model if you like. How does your lumped
circuit model explain those measured results?
--
73, Cecil http://www.qsl.net/w5dxp

On Sun, 2 Apr 2006 17:49:30 -0400, "Yuri Blanarovich"
wrote:

Sooo, nobody would try to do the experiment and SEE it, but rather keep
chasing the gay electron phasors charged with Kirchoffs through three way
intersections and blame Bush for it?

Visit:
http://www.powerloafing.com/home/
and select the first offering
Bush Goes Powerloafing

W:
Carl, this is really nice cubicle you've got here.
I work in a oval. That's a cubicle with -uh- oval corners.
Rove:
OK hand it over
(waiting for W to surrender the bottle of hooch)
Rove:
Not until after your second term. All of it!
(taking the bottle and a bag of white substance)
W:
You're such a buzz-kill.

There's also a great episode of Cubicle Carl done as a Star Trek
segment.

73's
Richard Clark, KB7QHC

Cecil Moore wrote:
Ian White GM3SEK wrote:
I don't intend to - that quotation is perfectly correct. It means
that in a test-case situation where the lumped model *does* apply,
the distributed model will give EXACTLY the same results.

Ian, you know nothing is "EXACTLY" the same. All you can say is that
the two models give acceptably similar results within a certain range
of accuracy.

NO!

Reality is not on trial here. We are examining your model which is
attempting to describe reality. In a test case where the loading is
DEFINED to be lumped inductance only, agreement with the lumped-circuit
model must be mathematically EXACT.

If one model is a true subset of the other, then as we come closer and
closer to the idealized test case, all the extra terms in the bigger
model will tend to zero leaving only the subset model. In the limit, the
agreement is indeed exact.

(For example, to take up your earlier mis-statement, circuit theory for
DC is a true subset of circuit theory for AC/RF. Set "w" (omega) to zero
and you're left with only the DC relationships. But there is no
discontinuity - as w gets smaller and smaller there is no sudden jump to
a whole new theory. When w is exactly zero, we expect exact mathematical
agreement with DC theory... and of course we get it.)

We do not expect any real-life loading coil to behave exactly like a
lumped inductance, so we cannot physically construct a perfect test
case. But we can envisage a perfect test case in order to test the
model; and for that, we are entitled to demand exact results.

I'm sorry, but all this is Scientific Method 101. Most people don't need
to understand this stuff in detail; though if they do, most people can
also appreciate the compelling logic of it.

You have put yourself in a position where you do need to understand
scientific logic in some detail, and follow the rules that logic lays
down... but you don't.

This is the test case that I'm trying to make you apply, to check
that with a lumped-inductance load, your antenna theory predicts the
correct behaviour, namely no phase shift in the current through a
lumped inductance.

:-) That's like proving there's no loss in a lossless transmission
line, Ian. Please send me a 100 uH lumped inductance and I will
run some tests on it and report back to you. What do you want to
bet the lumped circuit model will be wrong?

Some people have a problem with their model trying to dictate reality.
You seem to have fallen into that trap. Allow me to raise my voice.

THERE IS NO SUCH THING IN REALITY AS A LUMPED INDUCTANCE!!!!


No, of course there isn't. It is either an approximation or - as in this
case - a simplified situation that we can use to check whether theories
make sense.

Remember, it is your theory that we're trying to test. The challenge is
for you to show that your particular application of the distributed
circuit model works correctly.

In a test case where the loading coil comes closer and closer to
behaving like a lumped circuit, your model must do the same as all
successful distributed models do. All the complications must drop away,
giving closer and closer agreement to the behaviour of an antenna loaded
by pure inductance only. In the limit where the loading is pure lumped
inductance, the agreement must be mathematically EXACT.

I am sure this can be done using a standing wave analysis for a
coil-loaded antenna. I am equally sure that you have not achieved that.



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

Cecil Moore wrote:
Tom Donaly wrote:

Whatever. I'd still like to see his derivations.


"Optics", by Hecht, 4th edition, page 289.

The intensity of a light beam is associated with the E-field
so Hecht's equations are in relation to the E-field.

Speaking of the light standing wave: "The composite
disturbance is then:

E = Eo[sin(kt+wt) + sin(kt-wt)]

Applying the indentity

sin A + sin B = 2 sin 1/2(A+B)*cos 1/2(A-B)

E(x,t) = 2*Eo*sin(kx)*cos(wt)"

Hecht says the standing wave "profile does not move through
space".

I have said the RF standing wave current profile does not move
through a wire.

Hecht says the standing wave phasor "doesn't rotate at all,
and the resultant wave it represents doesn't progress through
space - it's a standing wave."

I have said the same thing about the RF standing wave current
phasor.

Hecht says the standing wave transfers zero net energy. I have
said the same thing about RF standing waves.

If it's a solution to the wave equation it's o.k., Cecil, but
Hecht is still not using the case where there is a phase difference
between the two waves. If it isn't in the original equation it
won't be in the final version since they're just two ways of
saying the same thing. That's fine because it's the wrong
equation anyway for what you want, which involves impedances
and length, which you probably don't want to deal with because
you're probably under the impression they're just virtual and
not real, and so not worthy of inclusion in your theory.
73,
Tom Donaly, KA6RUH

Cecil Moore wrote:

Yuri Blanarovich wrote:

It has been shown epxerimentally and also by EZNEC when modeled
properly as solenoid or loading stub. Yea, the "other" zero size coils
don't show that, EZNEC confirms that.


As a data point, the results of modeling a coil as a lumped
inductor Vs a helical coil are NOT the same in EZNEC. EZNEC
disagrees with itself.

I am much more inclined to trust the helically modeled inductance
than the lumped inductance.

As Dr. Corum says: "Distributed theory encompasses lumped circuits
and always applies." In other words, the Distrubuted network model
is a superset of the lumped circuit model.

There is no "helically modeled inductance" in Corum's work. They
specifically state that there is none. Instead, they use a substitute,
which Reg does, too, and develop their theory from there. Has it ever
occurred to you, Cecil, that just as lumped circuit analysis may not
be appropriate for everything due to its underlying assumptions, that
circuit theory may fail because you can't always reduce the electrical
world to current, voltage and length? When are you going to consider
field theory in your analysis, Cecil? It might come in handy in
any attempt to understand something as complex as a three dimensional coil.
73,
Tom Donaly, KA6RUH

Tom Donaly wrote:
If it's a solution to the wave equation it's o.k., Cecil, but
Hecht is still not using the case where there is a phase difference
between the two waves.

Yes, he is, Tom. The phase *disappears* when you add the two
traveling waves. That you don't recognize that fact of physics
is the source of your misconception. The forward and reflected
wave phasors are rotating in opposite directions at the same
angular velocity. That makes their sum a constant phase value
for half the cycle and the opposite constant phase value for
the other half of the cycle.

I and Richard Harrison have already explained that a number of
times quoting Kraus and Terman.

Here are a number of problems. I(f) is forward current and
I(r) is reflected current. Please everybody, perform the
following phasor additions where I(f)+I(r) is the *standing
wave current*:

I(f) I(r) I(f)+I(r)

1 amp at 0 deg 1 amp at 0 deg _________________

1 amp at -30 deg 1 amp at +30 deg _________________

1 amp at -60 deg 1 amp at +60 deg _________________

1 amp at -90 deg 1 amp at +90 deg _________________

1 amp at -120 deg 1 amp at +120 deg _________________

1 amp at -150 deg 1 amp at +150 deg _________________

1 amp at -180 deg 1 amp at +180 deg _________________

If you guys will take pen to paper and fill in those blanks
you will uncover the misconception that has haunted this
newsgroup for many weeks. If you need help with the math,
feel free to ask for help.
--
73, Cecil http://www.qsl.net/w5dxp

Tom Donaly wrote:
When are you going to consider
field theory in your analysis, Cecil?

That's a fair question, Tom. The answer is just as soon as someone
comes up with an example for which the distributed network model
fails. We have plenty of examples where the lumped circuit model
fails but not one example yet that the distributed network model
won't handle.
--
73, Cecil http://www.qsl.net/w5dxp

Cecil Moore wrote:
(snip)
Here are a number of problems. I(f) is forward current and
I(r) is reflected current. Please everybody, perform the
following phasor additions where I(f)+I(r) is the *standing
wave current*:

I(f) I(r) I(f)+I(r)

1 amp at 0 deg 1 amp at 0 deg 2 A @ 0 deg

1 amp at -30 deg 1 amp at +30 deg 1.72 A @ 0 deg

1 amp at -60 deg 1 amp at +60 deg 1 A @ 0 deg

1 amp at -90 deg 1 amp at +90 deg 0 A @ 0 deg

1 amp at -120 deg 1 amp at +120 deg 1 A @ 180 deg

1 amp at -150 deg 1 amp at +150 deg 1.72 A @ 180 deg

1 amp at -180 deg 1 amp at +180 deg 2 A @ 180 deg

If you guys will take pen to paper and fill in those blanks
you will uncover the misconception that has haunted this
newsgroup for many weeks. If you need help with the math,
feel free to ask for help.

What misconception? That all current in a standing wave has the same
phase, rather than one of two possible phases?

John Popelish wrote:
What misconception? That all current in a standing wave has the same
phase, rather than one of two possible phases?

The misconception is not yours, John. W7EL used that current to
try to measure the phase shift through a coil and so did W8JI
who came up with an unbelievable 3 nS.
--
73, Cecil http://www.qsl.net/w5dxp

Cecil Moore wrote:

Tom Donaly wrote:

If it's a solution to the wave equation it's o.k., Cecil, but
Hecht is still not using the case where there is a phase difference
between the two waves.


Yes, he is, Tom. The phase *disappears* when you add the two
traveling waves. That you don't recognize that fact of physics
is the source of your misconception. The forward and reflected
wave phasors are rotating in opposite directions at the same
angular velocity. That makes their sum a constant phase value
for half the cycle and the opposite constant phase value for
the other half of the cycle.

I and Richard Harrison have already explained that a number of
times quoting Kraus and Terman.

Here are a number of problems. I(f) is forward current and
I(r) is reflected current. Please everybody, perform the
following phasor additions where I(f)+I(r) is the *standing
wave current*:

I(f) I(r) I(f)+I(r)

1 amp at 0 deg 1 amp at 0 deg _________________

1 amp at -30 deg 1 amp at +30 deg _________________

1 amp at -60 deg 1 amp at +60 deg _________________

1 amp at -90 deg 1 amp at +90 deg _________________

1 amp at -120 deg 1 amp at +120 deg _________________

1 amp at -150 deg 1 amp at +150 deg _________________

1 amp at -180 deg 1 amp at +180 deg _________________

If you guys will take pen to paper and fill in those blanks
you will uncover the misconception that has haunted this
newsgroup for many weeks. If you need help with the math,
feel free to ask for help.

Cecil, if you don't put any phase information in your
original formula it won't be there when you say the
same thing some other way. But if you
do put it in there, then it has to affect both formulas.
If it disappears, you've done something wrong. If you and
Harrison can't figure out how to extract phase information
from a standing wave you should return your diplomas to
wherever you got them from.
73,
Tom Donaly, KA6RUH
(P.S. Let me give you a hint: first you have to find
out what phase means in a standing wave on a transmission
line. You probably already think you know, though, so I
don't expect you to bother much about it.)