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"Cecil Moore" wrote in message
...
John KD5YI wrote:
"Cecil Moore" wrote in message
A 75m Texas Bugcatcher loading coil certainly
qualifies as a distributed load being about
1/8WL long.

A 75m Texas Bugcatcher loading coil is about 30 feet long?

*Electrically*, yes. Its velocity factor calculates
out to be about 0.02 at 4 MHz and it is physically
0.563 feet long. 0.563'/0.02 = ~28 feet.

At 4 MHz, a 75m Texas Bugcatcher coil replaces ~28 feet
of wire in the antenna. That is ~41 degrees at 4 MHz.
(Note there is about 44 feet of wire in a 75m Texas
Bugcatcher loading coil.)


Using your argument, I could buy an inductor wound on a toroid core and
claim it is a "distributed" component because it "electrically" replaces
some calculated "degrees" or "feet" of wire at some frequency.

You appear to be trying to make lumped components into distributed
components to suit your arguments. Shame on you.

John

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On May 4, 8:17*am, "John KD5YI" wrote:
"Cecil Moore" wrote in message

...



John KD5YI wrote:
"Cecil Moore" wrote in message
A 75m Texas Bugcatcher loading coil certainly
qualifies as a distributed load being about
1/8WL long.

A 75m Texas Bugcatcher loading coil is about 30 feet long?

*Electrically*, yes. Its velocity factor calculates
out to be about 0.02 at 4 MHz and it is physically
0.563 feet long. 0.563'/0.02 = ~28 feet.

At 4 MHz, a 75m Texas Bugcatcher coil replaces ~28 feet
of wire in the antenna. That is ~41 degrees at 4 MHz.
(Note there is about 44 feet of wire in a 75m Texas
Bugcatcher loading coil.)

Using your argument, I could buy an inductor wound on a toroid core and
claim it is a "distributed" component because it "electrically" replaces
some calculated "degrees" or "feet" of wire at some frequency.

You appear to be trying to make lumped components into distributed
components to suit your arguments. Shame on you.

John

Good for you John, You have no idea of the years I have stated such to
the sneers of this group. They just don't accept change!

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Art Unwin wrote:
I suspect that Corum made some approximations.

Of course, they are approximations. The wire
diameter doesn't even appear in the equation.
Quoting the Corum paper:

"A useful engineering *approximation* has
been found for the fundamental resonance of
helices ...".

"... an *approximation* for M has been determined
by Kandoian and Sichak which is appropriate for
quarter-wave resonance ... for helices with
diameters considerably less than a free-space
wavelength".

"We have found that this expression gives acceptable
results (errors less than 10%) for most practical
applications that involve wave propagation on
helical resonators ...".
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

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On Mon, 04 May 2009 13:17:13 GMT, "John KD5YI"
wrote:

"Cecil Moore" wrote in message
A 75m Texas Bugcatcher loading coil certainly
qualifies as a distributed load being about
A 75m Texas Bugcatcher loading coil is about 30 feet long?
*Electrically*, yes. Its velocity factor calculates
You appear to be trying to make lumped components into distributed
components to suit your arguments. Shame on you.

Hi John,

All the right words are there. They are expressed in a familiar
order. There is the *implication by special marking* that can be used
equally as a point of reversed qualification - the back exit.

So, in retrospect (a very short one of the six lines above), this is
obviously a problem of you don't understand what you were thinking
when you asked your question. Unfortunately, you could have as easily
agreed only to have Cecil point out, through the same chain of
discussion above, you are wrong - you don't understand what you were
thinking.

73's
Richard Clark, KB7QHC

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John KD5YI wrote:
Using your argument, I could buy an inductor wound on a toroid core and
claim it is a "distributed" component because it "electrically" replaces
some calculated "degrees" or "feet" of wire at some frequency.

Sorry, that's not true. Toroidal inductors are not covered
by my argument adopted from Dr. Corum's IEEE paper. Toroidal
inductors are not being discussed at all - except by people
afraid to discuss large air-core loading coils. My argument
(based on Dr. Corum's assertions) apply *only* to large,
air-core coils that meet the conditions listed on page 4 of
Dr. Corum's paper at:

http://www.ttr.com/TELSIKS2001-MASTER-1.pdf

A 75m Texas Bugcatcher coil is an example of the type
of air-core loading coil that I am talking about. It's
about 6" diameter, 4 tpi, and 6.75" long. Dr. Corum's
equations indicate a VF of ~0.02 for such a coil used
on 4 MHz which makes it electrically about 28 degrees
long.

You appear to be trying to make lumped components into distributed
components to suit your arguments. Shame on you.

No, just the opposite. I am trying to keep others
from considering large air-core distributed network
loading coils to be lumped components (which they
obviously are not). Dr. Corum says any coil electrically
longer than 15 degrees (0.04WL) needs to be treated
as a distrubuted network, not as a lumped-circuit.

Here are some of Dr. Corum's class notes:

http://www.ttr.com/corum/index.htm

Here's a quote: "In the following note, we will show
why one needs transmission line analysis (or Maxwell's
equations) to model these electrically distributed
structures. Lumped circuit theory fails because it's
a *theory* whose presuppositions are inadequate. Every
EE in the world was warned of this in their first
sophomore circuits course."

Yet W8JI reports a 3 nS delay through a 100 turn, 10"
long, 2" dia loading coil on 4 MHz, an obvious
impossibility since such a large, long air-core inductor
is nowhere near to being a lumped-inductor. At ~37
degrees, based on Dr. Corum's equations, it is more
than double the 15 degrees that is the point at
which the lumped-circuit model starts to fail.

37 degrees gives a delay of ~25 nS on 4 MHz. That's
approximately what one would measure if one used a
traveling wave for the measurement instead of a
standing wave (which doesn't change phase with
distance). W8JI's "measurements" were off by almost
a magnitude.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

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On May 4, 10:32*am, Cecil Moore wrote:
Art Unwin wrote:
I suspect that Corum made some approximations.

Of course, they are approximations. The wire
diameter doesn't even appear in the equation.
Quoting the Corum paper:

"A useful engineering *approximation* has
been found for the fundamental resonance of
helices ...".

"... an *approximation* for M has been determined
by Kandoian and Sichak which is appropriate for
quarter-wave resonance ... for helices with
diameters considerably less than a free-space
wavelength".

"We have found that this expression gives acceptable
results (errors less than 10%) for most practical
applications that involve wave propagation on
helical resonators ...".
--
73, Cecil, IEEE, OOTC, *http://www.w5dxp.com

Cecil you never once backed me up on Maxwell/lumped loads
saga on this group. Now you point to several improvisations on
obtaining
lumped load affects by other avenues where not one theory satisfies
the physics community. If one starts off with the acceptance of errors
in the range of 10 % where you are also allowed to jump from one
theory to another so the acceptable discrepancy can be satisfied then
this is dishonest with respect to physics.
As I have pointed out many times, Maxwell's laws do not pass rigourous
examination when lumped loads are introduced. With that said, I do not
quarrel your aproach with respect to degrees of antenna in terms of
approximations but when it is applied to antennas on this group
adherence to Maxwell is required, which is inclusiveness of all forces
as opposed to planar designs (yagi's) where liberties are taken in not
accounting for all forces within the arbitrary borders. It is this
very aproach which have allowed designs of antennas to move away from
the edicts of Maxwell and the equilibrium requirements of Newton which
provide for maximum efficiency.
It is the silence of you and other respected people on this group that
is responsible for the lack of advancement in antenna design over the
last hundred years by not adhering to classical physics.
Nothing personal intended, but this does exhibit a representation of
the engineers in this group in misleading other hams with respect to
this hobby.
Best regards
Art

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John KD5YI wrote:
"Cecil Moore" wrote in message
...
John KD5YI wrote:
"Cecil Moore" wrote in message
A 75m Texas Bugcatcher loading coil certainly
qualifies as a distributed load being about
1/8WL long.
A 75m Texas Bugcatcher loading coil is about 30 feet long?
*Electrically*, yes. Its velocity factor calculates
out to be about 0.02 at 4 MHz and it is physically
0.563 feet long. 0.563'/0.02 = ~28 feet.

At 4 MHz, a 75m Texas Bugcatcher coil replaces ~28 feet
of wire in the antenna. That is ~41 degrees at 4 MHz.
(Note there is about 44 feet of wire in a 75m Texas
Bugcatcher loading coil.)


Using your argument, I could buy an inductor wound on a toroid core and
claim it is a "distributed" component because it "electrically" replaces
some calculated "degrees" or "feet" of wire at some frequency.

You appear to be trying to make lumped components into distributed
components to suit your arguments. Shame on you.

John



It could be worse, John. He could claim that his loading coil replaces
a certain amount of period (time) in addition to length. That might be
too complex for him, though.
73,
Tom Donaly, KA6RUH

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On Mon, 04 May 2009 11:03:50 -0700, "Tom Donaly"
wrote:

It could be worse, John. He could claim that his loading coil replaces
a certain amount of period (time) in addition to length. That might be
too complex for him, though.

If he could put it to music, it might top the charts over Cat Stevens'
"Time in a Bottle."

73's
Richard Clark, KB7QHC

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On May 4, 1:24*pm, Richard Clark wrote:
On Mon, 04 May 2009 11:03:50 -0700, "Tom Donaly"

wrote:
It could be worse, John. He could claim that his loading coil replaces
a certain amount of period (time) in addition to length. That might be
too complex for him, though.

If he could put it to music, it might top the charts over Cat Stevens'
"Time in a Bottle."

73's
Richard Clark, KB7QHC

Hold on guys before you start to pile on. Now there is agreement
with respect to approximations, the original debate did not go away.
As Cecil pointed out the difference is in the order of a magnitude!
Somebody has some explanations to provide such as instruments used
were not calibrated as perfect as Richard demands which is why he
agrees with nobody.
Somebody is hiding from the truth and using a sprinkling of untruth to
cover their path.
It is either Roy and Tom or Cecil himself. All others follow their
role models lead.
Art

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Art Unwin wrote:
Cecil you never once backed me up on Maxwell/lumped loads
saga on this group.

Art, I remember the electron/photon discussion but
I do not remember any Maxwell/lumped loads discussion.
I often skip threads that I do not understand.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com