Loading Coils; was : Vincent antenna
 

Roger wrote:
Roy is giving good advice to study time domain reflectometry.

That's a good way to find out what is in each of
those black boxes.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

AI4QJ wrote:
"Roy Lewallen" wrote:
Does the new knowledge include a way to tell the
four black boxes apart at one steady state frequency, or how many
"electrical degrees" each one contains?

Where did the extra black box come from and who made the restriction on
frequency? I should be able to use any voltage or frequency I want, don't
you think?

Just raise the stakes, Dan. Challenge Roy to prove the
impedance is -j567 without applying a source signal.

I wonder what is the ulterior motive in arbitrarily
handicapping the person doing the measurements?

Roy mentioned the TDR for the other problem. Seems a TDR
is exactly the instrument needed to find out what is in
each of those black boxes. Or just order the black boxes
already specified with its s22 parameter stamped on the
black box.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Keith Dysart wrote:
When allowed to excite the black boxes with different
signals there are many ways to determine an internal
equivalent circuit. The question here was did the various
ways of making -j567 affect the results for sinusoidal
single frequency excitation.

Yes, it illustrated the two separate and different
IEEE definitions for "impedance", one a cause for
the voltage to current ratio and one a result of a
voltage to current ratio.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Keith Dysart wrote:
When I look at one of those coils, I think it is one big complicated
mess of distributed capacitance and inductance. There is intra and
inter turn capacitance and capacitance to ground. A mess.

Some say such a coil can be adequately modelled using a lumped
inductor.

I'm afraid you have fallen for someone else's mis-statement of that
point of view.

The most recent posting about lumped inductance was probably mine. It
states both the value and the limitations of this approach.

"Lumped inductance is often a good approximation to reality, so [most
models other than Cecil's] very sensibly use that as their
starting-point. Then they can progressively apply corrections for the
distributed properties of a real-life inductors. The smaller those
corrections are, the simpler the model becomes.

In practical terms, a lumped-inductance model will take you straight to
a buildable prototype. The necessary corrections can then be applied by
mechanical adjustment, without needing to model the distributed
properties of the loading coil in detail. Such models are to be found in
G4FGQ's MIDLOAD program, ON4UN's 'Antennas for Low Band DXing' and other
handbooks.

There was also an excellent theoretical treatment by Boyer in 'Ham
Radio', which shows in detail how the model of an antenna as an
unterminated transmission line is COMPLETELY capable of incorporating
lumped inductance."



--

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

Loading Coils; was : Vincent antenna
 

AI4QJ wrote:
"Keith Dysart" wrote:
The Smith chart is normalized for impedance
and frequency.

The smith chart is normalized *only* by Zo.

Tell me, how is Zo related to frequency :-) Or better, tell me how the smith
chart is normalized by frequency?

The Smith Chart is NOT normalized to a frequency.
EZNEC outputs frequency sweep data that can be
imported into MicroSmith.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Roy Lewallen wrote:
Sure, you can do anything you like. But can you tell the boxes apart by
measuring at just one frequency (the one at which their impedances are
the same)? Do they have the same or different numbers of "electrical
degrees" at that frequency?

I'll do you one better with one more unreasonable condition.
Let's see you do it without applying any source power.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Richard Clark wrote:
How about that in the first place, particles
don't inhabit the explanation at all?

How about quantum physics telling us that nothing
except particles exist? You really want to take
on the body of quantum physics and physicists?
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Keith Dysart wrote:
On Dec 14, 1:52 pm, Cecil Moore wrote:
Do you think electrons support mechanical waves?

Simplicity itself. Electrons are charged. Like charges
repel. Move an electron and the next electron will tend
to move away.

So by your own admission, those are not mechanical waves.
Like charge repulsion is *NOT a mechanical phenomenon*.
Those electrons never touch each other. They are repelled
by the photons they are emitting.

I've been told that near the antenna, there are just
varying electric and magnetic fields and that some
distance from the antenna the electro-magnetic
wave forms. How does the varying field turn into a
photon?

The varying field ***IS*** made up of *PHOTONS*.
All electromagnetic fields consist of photons!
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Roy Lewallen wrote:
Did you also conclude, then, that all
the boxes contain the same number of "electrical degrees"?

Yes, all the boxes contain the same number of electrical
degrees. That's why we can calculate the number of
electrical degrees at the impedance discontinuity.

Hint: That number of electrical degrees for a capacitor
is the same as the gamma angle for the reflection
coefficient.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Keith Dysart wrote:
I am not convinced. The value is still being determined
by accounting for all the other phase shifts and then
subtracting from 90. I would be more convinced of the
utility if the value could be computed from first principles
and then used, for example, to compute the length of
the whip.

That can easily be done. The s-parameter equations do
exactly that when applied at an impedance discontinuity.
a1, a2, b1, and b2 are all phasors each with an amplitude
and a phase.


b1 = s11*a1 + s12*a2

b2 = s21*a1 + s22*a2

The angle between b1 and b2 is the phase shift at
the impedance discontinuity.

Now are you convinced?

What happened to the missing 37 degrees?

Perhaps, like the missing dollar, it is simply a number
with no meaning.

Perhaps, if you would do the s-parameter analysis, you
would see the phase shift for yourself so it would
have meaning to you.

As an aside, allowing the possibility of this "phase shift" at
the joint, how would you compute the phase shift when a
parallel stub is used, or when multiple parallel stubs are
used to obtain the desired result? And which stub will be
used to define the 90 degrees from which the others are
subtracted?

Please don't complicate things before you have understood
the simple things.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Dave wrote:
likewise in transmission lines, forget photons,
use currents and voltages, you will never run into a case where photons are
necessary, or even useful, in transmission line problems.

Fields and waves *are* quantized photons. Radiation
from an antenna is a lot easier to understand as
a cloud of photon particles that escape rather than
the EM fields that break away like soap bubbles.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Cecil Moore wrote:
Radiation
from an antenna is a lot easier to understand as
a cloud of photon particles that escape rather than
the EM fields that break away like soap bubbles.

Cecil,

Only in your dreams. Antenna photons may be great for your handwaving
explanations. Let's see you do the math. Do you suppose there is a
conspiracy among the many authors of text books to use only the
cumbersome wave formulations? Are photons too easy? Would the textbooks
then be unneeded?

73,
Gene
W4SZ

Loading Coils; was : Vincent antenna
 

Richard Clark wrote:
On Fri, 14 Dec 2007 11:35:25 -0800, Roger wrote:

The derivation did several things for me. It clearly explains why we do
not have a runaway current when we first connect a voltage to a
transmission line,

Hi Roger,

It doesn't describe why the current flows in the first place, does it?

Are you asking for a discussion about batteries?

what transmission line impedance is, that moving
particles can not be the entire explanation for the electromagnetic wave
(because the energy field moves much faster than the electrons), and
puts into place a richer understanding of inductance.

And here we begin on the wonderful world of spiraling explanations,
not found in the original source: "Moving particles cannot be the
entire explanation?" How about that in the first place, particles
don't inhabit the explanation at all?
You originally asked what I learned from Zo = 1/cC. What I learn from
it may not be obvious to you. Discussing particles would be a
completely new discussion.

What is your point here? Are implying that the formula is incorrect
because a sine wave was not mentioned in the derivation. I am sure that
all of the sophisticated readers of this news group understand that the
sharp corner of the square wave is composed of ever higher frequency
waves.

I'm even convinced most of them would not call this DC too.

We agree on this.

We would complicate the concept and thereby begin to confuse people if
we insisted on using the "Stepped Wave" term.

They would've been confused anyway.

They don't seem to be confused, once the limitations of human language
are overcome. We have many very intelligent and astute observers in
this newsgroup.

It is a simple step to
recognize that if we can make a wave front with one battery, we can use
a lot of batteries and carefully place and switch them to form a sine
wave. The more batteries and switches, the better the representation.

And this is still DC?

Do you really know that mother nature is not ALWAYS operating in small
steps of DC? How small is the scale that you can resolve to? I can not
answer where DC starts and stops. Maybe you can?

Is there some harm in considering Zo = 1/cC?

This is best left in the privacy of the home.

It seems that a simple yes or no answer could suffice here. How is
"privacy in the home" related to Zo = 1/cC?


However, none of your comments respond to the question: What is with
this death grip on DC? What makes it so important that it be so
tightly wedded to Waves? What mystery of the cosmos is answered with
this union that has so long escaped the notice of centuries of trained
thought?

73's
Richard Clark, KB7QHC

Please elaborate about the "death grip on DC". How is DC related to
waves, or better, where does DC stop and waves begin? Should we never
consider any portion of a wave to be DC like we do in calculus routinely?

My original remark about about Zo = 1/cC expressed my surprise that such
a relationship existed. It was not an original discovery by me, only
new knowledge to me. From your reaction, this must be the first time
you have run across the equation and how it might be derived. I
provided two links to web pages where others have derived the equation
from a different aspect, and even more pathways exist. It seems to be a
very fundamental relationship despite being not well known or wide used.

73, Roger, W7WKB

Loading Coils; was : Vincent antenna
 

On Sat, 15 Dec 2007 08:24:06 -0800, Roger wrote:

It doesn't describe why the current flows in the first place, does it?

Are you asking for a discussion about batteries?

Hi Roger,

"About" batteries?

You originally asked what I learned from Zo = 1/cC.

Actually, my original was:
On Thu, 13 Dec 2007 11:08:54 -0800, Richard Clark
wrote:
Hi Roger,
This last round has piqued my interest when we dipped into DC. Those
"formulas" would lead us to a DC wave velocity?
And I have repeated that request at frequent intervals as DC having a
wave velocity is quite a departure from the catechism.

What I learn from
it may not be obvious to you. Discussing particles would be a
completely new discussion.

OK, a completely new discussion that perhaps was not in your interest
to raise or expand upon here. I see nothing productive in it either.

What is your point here? Are implying that the formula is incorrect
because a sine wave was not mentioned in the derivation. I am sure that
all of the sophisticated readers of this news group understand that the
sharp corner of the square wave is composed of ever higher frequency
waves.

I'm even convinced most of them would not call this DC too.

We agree on this.

So, are we to discard this phenomenon of the clumsy current bulge so
illustrated at one of your links? It seems to have injected this
aberrant usage of DC which then donned the mantle of Wave.

We would complicate the concept and thereby begin to confuse people if
we insisted on using the "Stepped Wave" term.

They would've been confused anyway.

They don't seem to be confused, once the limitations of human language
are overcome. We have many very intelligent and astute observers in
this newsgroup.

Then they are not confused, simple so stunned as to not ask the
questions you anticipate. I haven't seen any objections, other than
yours, to the term Stepped Wave. Are you referring to private
correspondence?

It is a simple step to
recognize that if we can make a wave front with one battery, we can use
a lot of batteries and carefully place and switch them to form a sine
wave. The more batteries and switches, the better the representation.

And this is still DC?

Do you really know that mother nature is not ALWAYS operating in small
steps of DC? How small is the scale that you can resolve to? I can not
answer where DC starts and stops. Maybe you can?

With great certainty and precision. I have measured the fundamental
units of DC out 7 places, traceable to the National Bureau of
Standards. I have also measured AC from sub-Hertz to 12GHz to the
highest precision and certainties in the same occupation. The body of
science and engineering is not confused about this demarcation.

For any purpose of discussion, DC is regarded by science and
engineering to mean either:
1. Static, non-changing potential (your discussion violates this);
2. Constant, unvarying current (your discussion also violates this).

If your current or voltage cannot subscribe to these commonly held
descriptions, your currents and voltages are not DC.

Is there some harm in considering Zo = 1/cC?

This is best left in the privacy of the home.

It seems that a simple yes or no answer could suffice here. How is
"privacy in the home" related to Zo = 1/cC?

I have stated the harm several times, repetition does not seem to be
adequate in that your having perceived benefit is a personal choice. I
see no reason to dwell on the subjective.

Please elaborate about the "death grip on DC".

How is DC related to
waves, or better, where does DC stop and waves begin?

It was your premise. If you cannot explain it (and I see absolutely
nothing that would help you explain it) - then this is obviously the
end of the matter to which I first (see that question above) asked you
about.

Should we never
consider any portion of a wave to be DC like we do in calculus routinely?

Calculus is done "by parts." In derivation DC is the first thing to
disappear! In integration, DC arrives as an unknown! If this
discussion of Calculus were to progress any further, it would involve
dt which imagines no past, no future, just now. DC comes equipped
with all three nailed down to the same value.

My original remark about about Zo = 1/cC expressed my surprise that such
a relationship existed. It was not an original discovery by me, only
new knowledge to me. From your reaction, this must be the first time
you have run across the equation and how it might be derived. I
provided two links to web pages where others have derived the equation
from a different aspect, and even more pathways exist. It seems to be a
very fundamental relationship despite being not well known or wide used.

It is no more fundamental than when Tennessee state law mandated that
the value of PI would be 22/7ths. Your fundamental is merely a
shortcut, not a fact of nature. Like that Tennessee law, you can't
use it for very much when push comes to shove. I certainly wouldn't
buy tires based on the circumference calculated from Tennessee law.

73's
Richard Clark, KB7QHC

Loading Coils; was : Vincent antenna
 

"Roger" wrote in message
. ..
My original remark about about Zo = 1/cC expressed my surprise that such a
relationship existed.

you should have gone with your gut and acknowledged the surprise by checking
your work and finding out why it doesn't exist... or why it is not used
instead of the real LC equations in all the text books.

It was not an original discovery by me, only new knowledge to me.

Ok, if it was not your discovery, quote a reputable source where it was
discovered.
btw, your referenced web page 'speedingedge.com' has the formula correct:
Z0 = 1/(C v)
note, the v, not c in the equation. and CL should be C sub L.
also the uci.edu site has the formula exactly the same, with v instead of c.
so start searching again for one that has c in the equation instead of v.


From your reaction, this must be the first time you have run across the
equation and how it might be derived. I provided two links to web pages
where others have derived the equation from a different aspect, and even
more pathways exist. It seems to be a very fundamental relationship
despite being not well known or wide used.

73, Roger, W7WKB

its the first time, and hopefully the last time i expect to see such an
error.

Loading Coils; was : Vincent antenna
 

Richard Clark wrote:
On Sat, 15 Dec 2007 08:24:06 -0800, Roger wrote:

It doesn't describe why the current flows in the first place, does it?
Are you asking for a discussion about batteries?

Hi Roger,

"About" batteries?

You originally asked what I learned from Zo = 1/cC.

Actually, my original was:
On Thu, 13 Dec 2007 11:08:54 -0800, Richard Clark
wrote:
Hi Roger,
This last round has piqued my interest when we dipped into DC. Those
"formulas" would lead us to a DC wave velocity?
And I have repeated that request at frequent intervals as DC having a
wave velocity is quite a departure from the catechism.

The formula will not give a "DC wave" velocity, but one can be found
from the experiment. First however, we must agree upon what unit we are
to assign a velocity to.

What I learn from
it may not be obvious to you. Discussing particles would be a
completely new discussion.

OK, a completely new discussion that perhaps was not in your interest
to raise or expand upon here. I see nothing productive in it either.

What is your point here? Are implying that the formula is incorrect
because a sine wave was not mentioned in the derivation. I am sure that
all of the sophisticated readers of this news group understand that the
sharp corner of the square wave is composed of ever higher frequency
waves.
I'm even convinced most of them would not call this DC too.
We agree on this.

So, are we to discard this phenomenon of the clumsy current bulge so
illustrated at one of your links? It seems to have injected this
aberrant usage of DC which then donned the mantle of Wave.

Perhaps this goes toward the definition of the unit of DC that we might
assign a velocity to?

We would complicate the concept and thereby begin to confuse people if
we insisted on using the "Stepped Wave" term.
They would've been confused anyway.
They don't seem to be confused, once the limitations of human language
are overcome. We have many very intelligent and astute observers in
this newsgroup.

Then they are not confused, simple so stunned as to not ask the
questions you anticipate. I haven't seen any objections, other than
yours, to the term Stepped Wave. Are you referring to private
correspondence?

Nope, just what I have seen on the news group.


It is a simple step to
recognize that if we can make a wave front with one battery, we can use
a lot of batteries and carefully place and switch them to form a sine
wave. The more batteries and switches, the better the representation.
And this is still DC?
Do you really know that mother nature is not ALWAYS operating in small
steps of DC? How small is the scale that you can resolve to? I can not
answer where DC starts and stops. Maybe you can?

With great certainty and precision. I have measured the fundamental
units of DC out 7 places, traceable to the National Bureau of
Standards. I have also measured AC from sub-Hertz to 12GHz to the
highest precision and certainties in the same occupation. The body of
science and engineering is not confused about this demarcation.

For any purpose of discussion, DC is regarded by science and
engineering to mean either:
1. Static, non-changing potential (your discussion violates this);
2. Constant, unvarying current (your discussion also violates this).

If your current or voltage cannot subscribe to these commonly held
descriptions, your currents and voltages are not DC.

My description of the experiment mentioned wave front several times. I
also assumed a steady current behind the wave front. Why are we
concentrating on the DC part to the exclusion of the wave front?

BTW, congratulations on measuring characteristics out to several decimal
places. That takes great care, precision, and skill.

Is there some harm in considering Zo = 1/cC?
This is best left in the privacy of the home.
It seems that a simple yes or no answer could suffice here. How is
"privacy in the home" related to Zo = 1/cC?

I have stated the harm several times, repetition does not seem to be
adequate in that your having perceived benefit is a personal choice. I
see no reason to dwell on the subjective.

Please elaborate about the "death grip on DC".

How is DC related to
waves, or better, where does DC stop and waves begin?

It was your premise. If you cannot explain it (and I see absolutely
nothing that would help you explain it) - then this is obviously the
end of the matter to which I first (see that question above) asked you
about.

This again goes to defining the unit of DC that we wish to assign a
velocity to.

Should we never
consider any portion of a wave to be DC like we do in calculus routinely?

Calculus is done "by parts." In derivation DC is the first thing to
disappear! In integration, DC arrives as an unknown! If this
discussion of Calculus were to progress any further, it would involve
dt which imagines no past, no future, just now. DC comes equipped
with all three nailed down to the same value.

Am I to understand that the only use of the term "DC" that you will
accept is "A steady state without beginning or end, having always
existed, and will exist forever more". Of course such a thing would not
have a "wave front"

My original remark about about Zo = 1/cC expressed my surprise that such
a relationship existed. It was not an original discovery by me, only
new knowledge to me. From your reaction, this must be the first time
you have run across the equation and how it might be derived. I
provided two links to web pages where others have derived the equation
from a different aspect, and even more pathways exist. It seems to be a
very fundamental relationship despite being not well known or wide used.

It is no more fundamental than when Tennessee state law mandated that
the value of PI would be 22/7ths. Your fundamental is merely a
shortcut, not a fact of nature. Like that Tennessee law, you can't
use it for very much when push comes to shove. I certainly wouldn't
buy tires based on the circumference calculated from Tennessee law.

73's
Richard Clark, KB7QHC

A shortcut assuredly. Also another view of the physical world. Use it
when helps understanding, and abandon it when the model fails. After
all, no matter what precision we measure to, we are just working with
models. Perhaps the next decimal of precision will reveal a flaw or
hole in logic.

73, Roger, W7WKB

Loading Coils; was : Vincent antenna
 

Ian White GM3SEK wrote:
"Lumped inductance is often a good approximation to reality, so [most
models other than Cecil's] very sensibly use that as their
starting-point.

For the umpteenth time, Ian, I don't have a model developed
by me. The model I use is the distributed network model
invented before I was born. Dr. Corum merely expanded upon
that model and I consider his concepts to be valid.

Your lumped circuit model seems more like a religion
than a valid tool of science. Zero phase shift through
a real-world loading coil? That requires faster than
light propagation thought by many experts to be
impossible.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Richard Clark wrote:
It is no more fundamental than when Tennessee state law mandated that
the value of PI would be 22/7ths.

Good grief, that goes against The Bible which says the
value of PI is 3.0 and "everyone knows" The Bible cannot
be wrong because God inspired it to be written that way.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Keith Dysart wrote:
Each of the different ways mentioned for obtaining -j567
will produce a different impedance if the frequency is
changed. They were all frequency dependant.

Moral: Change the frequency and then observe what one
is dealing with?

I suggest that there is no value in thinking about
the "phase shift" at the discontinuity (which depending
on the black box chosen might not be present), and
merely think about the results of connecting the
-j567 impedance to the 600 ohm line.

The refusal to think about the phase shift at the
discontinuity is what got this whole thread started.

All you have to do to observe the calculated phase
shift is to use the s-parameter equations. When you
have done that, please get back to us.

Cecil did not answer the question, so I will
pose it again. If knowing the phase shift at
the terminals of the black box is important,
and you can not know it without knowing the
internals of the box, given a black box of
unknown internals but told that its terminals
present -j567 at the frequency of interest,
would you refuse to calculate the length
of 600 ohm line needed to produce 0 ohms?

Or asking the question another way: Is there
really a Santa Claus and a God?

Let's see you prove that it is really -j567 ohms
without applying any signal at all. How's that
for a requirement?
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

AI4QJ wrote:
The value is more obvious when applying the concept to a loaded whip
antenna.

Sometimes an epiphany takes place in an associated
area. I was searching for the loaded whip answer
when I stumbled upon the dual-Z0 stubs, a subject
that seems to have been ignored in the amateur
literature.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Cecil Moore wrote:
The angle between b1 and b2 is the phase shift at
the impedance discontinuity.

Sorry, I had a migraine and a brain fart there.
The angle between b1 and a2 is the phase shift
at the impedance discontinuity. It's absolute
value should be the same as the angle between
a1 and b2 at the impedance discontinuity.

I apologize for my brain fart.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

On Sat, 15 Dec 2007 12:04:34 -0800, Roger wrote:

Am I to understand that the only use of the term "DC" that you will
accept is "A steady state without beginning or end, having always
existed, and will exist forever more". Of course such a thing would not
have a "wave front"

Hi Roger,

Exactly. This has always been the definition for DC. For anything
else, there are already terms that have been provided for decades,
unto more than a century.

73's
Richard Clark, KB7QHC

Loading Coils; was : Vincent antenna
 

AI4QJ wrote:
I vote for 3.2 and so did the Indiana legislature by 67 - 0!

I'm sorry, Dan, my 3.0 Bible reference is a lot older than
that. Now if I could only find it.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Richard Clark wrote:
On Sat, 15 Dec 2007 12:04:34 -0800, Roger wrote:

Am I to understand that the only use of the term "DC" that you will
accept is "A steady state without beginning or end, having always
existed, and will exist forever more". Of course such a thing would not
have a "wave front"

Hi Roger,

Exactly. This has always been the definition for DC. For anything
else, there are already terms that have been provided for decades,
unto more than a century.

73's
Richard Clark, KB7QHC

Hi Richard,

OK. I will remember this for making future discussions more exact.

73, Roger, W7WKB

Loading Coils; was : Vincent antenna
 

On Dec 15, 3:23 pm, Cecil Moore wrote:
Keith Dysart wrote:
Cecil did not answer the question, so I will
pose it again. If knowing the phase shift at
the terminals of the black box is important,
and you can not know it without knowing the
internals of the box, given a black box of
unknown internals but told that its terminals
present -j567 at the frequency of interest,
would you refuse to calculate the length
of 600 ohm line needed to produce 0 ohms?

Or asking the question another way: Is there
really a Santa Claus and a God?

Perhaps. Though I notice that you still have not
answered the question.

....Keith

Loading Coils; was : Vincent antenna
 

Keith Dysart wrote:

Keith Dysart wrote:
given a black box of
unknown internals but told that its terminals
present -j567 at the frequency of interest,
would you refuse to calculate the length
of 600 ohm line needed to produce 0 ohms?

Though I notice that you still have not
answered the question.

Why would anyone refuse to calculate the length of
600 ohm line needed to produce 0 ohms? I think I
was the first to calculate it at 43.4 degrees.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Cecil Moore wrote:
Ian White GM3SEK wrote:
"Lumped inductance is often a good approximation to reality, so [most
models other than Cecil's] very sensibly use that as their
starting-point.

For the umpteenth time, Ian, I don't have a model developed
by me. The model I use is the distributed network model
invented before I was born. Dr. Corum merely expanded upon
that model
and I consider his concepts to be valid.

That last line makes it "your model" by adoption - and certainly "your
model" by advocacy.

Your lumped circuit model seems more like a religion
than a valid tool of science. Zero phase shift through
a real-world loading coil?

That wasn't what I said. What I did say - and you cut - was:

"Lumped inductance is often a good approximation to reality, so [most
models other than Cecil's] very sensibly use that as their
starting-point. Then they can progressively apply corrections for the
distributed properties of a real-life inductors. The smaller those
corrections are, the simpler the model becomes.

In practical terms, a lumped-inductance model will take you straight to
a buildable prototype."




--

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

Loading Coils; was : Vincent antenna
 

On Dec 16, 1:18 am, Cecil Moore wrote:
Keith Dysart wrote:
Keith Dysart wrote:
given a black box of
unknown internals but told that its terminals
present -j567 at the frequency of interest,
would you refuse to calculate the length
of 600 ohm line needed to produce 0 ohms?

Though I notice that you still have not
answered the question.

Why would anyone refuse to calculate the length of
600 ohm line needed to produce 0 ohms? I think I
was the first to calculate it at 43.4 degrees.

Exactly. Why would anyone refuse?

So the next question is: What is the phase change
at the terminals of the black box?

1) -93 degrees? (previous answer when it was a capacitor)
2) 36.6 degrees? (previous answer when it was 10 degrees of 100 ohm
line)
3) 0 degrees? (previous answer when it was 46.6 degrees of 600 ohm
line)
4) undecidable?
5) undefined?
6) irrelevant?
7) ???

....Keith

Loading Coils; was : Vincent antenna
 

Ian White GM3SEK wrote:
In practical terms, a lumped-inductance model will take you straight to
a buildable prototype."

If you are a technician or a hobbyist, by all means
use the shortcuts. If you are an engineer or physicist,
to do so will lead your concepts astray.

Take the use of standing-wave current to try to measure
the delay through a 75m mobile loading coil. The results
of using the lumped-inductance model are off by a magnitude.
A 75m mobile loading coil is a distributed network that
is an appreciable percentage of a wavelength. As such, the
lumped inductance model is inadequate for analysis.

Here is a quote from my web page:

Many experiments and measurements have been made on loading
coils using net standing wave current. A lack of understanding
of the nature of standing wave current has resulted in some
strange and magical assertions about current through a loading
coil. The equation for standing wave current is of the form:

I(x,t) = Imax sin(kx) cos(wt)

For any point location 'x', it can be seen that the standing
wave current is not "flowing" in the ordinary sense of the word
but rather, is just oscillating in place at that fixed point.
EZNEC confirms that the phase of standing wave current is essentially
constant all up and down a typical HF mobile antenna and therefore
cannot be used to make a valid measurement of the phase shift (delay)
through a loading coil (or even through a wire.) The validity of that
statement is obvious if one understands the implications of the
standing wave current equation above. In fact, we can just as easily
write the standing wave current equation as:

I(x,t) = Imax sin(kx) cos(-wt)

We can reverse the direction of rotation of the standing wave
current phasor and still have the same value of current. Standing
wave current really doesn't have a direction of flow.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Keith Dysart wrote:
Why would anyone refuse to calculate the length of
600 ohm line needed to produce 0 ohms? I think I
was the first to calculate it at 43.4 degrees.

Exactly. Why would anyone refuse?

Nobody has refused so it is a rhetorical question
the meaning of which is obscure.

So the next question is: What is the phase change
at the terminals of the black box?

You list the phase changes at the terminals of the
black boxes. An s-parameter analysis will prove those
are valid values. Have you done that s-parameter
analysis yet?

b1 = s11*a1 + s12*a2

b2 = s21*a1 + s22*a2

The phase shift is the relative phase between b1 and a2.
And also the relative phase between b2 and a1.

1) -93 degrees? (previous answer when it was a capacitor)

I might be wrong about that one. It might instead be
180 - 93, but that would just be a stupid math mistake.
The main thing is that it is different from the other two.

2) 36.6 degrees? (previous answer when it was 10 degrees of 100 ohm
line)
3) 0 degrees? (previous answer when it was 46.6 degrees of 600 ohm
line)

There's nothing wrong with those answers except maybe
a stupid math error. Each condition indeed does have a
different phase shift that can be measured one inch on
the other side of the terminals if one is simply allowed
to make those measurements. If s11 is measured and stamped
on the black boxes, the phase changes can be easily
calculated.

This is an example of how models can get you into trouble.
Not allowing us to look inside the black box doesn't change
the laws of physics and make all the phase shifts the same.
It just means that the phase shifts are unknown and need
to be measured.

Using that same logic, if you were shackled at the bottom
of Carlsbad Caverns, night and day would stop happening
just because you couldn't see it happening.

Do you really expect us to believe that the phase shift
is the same for all the black boxes but changes abruptly
when the reflection coefficients are measured?
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Keith Dysart wrote:
So the next question is: What is the phase change
at the terminals of the black box?

It just occurred to me that you and I may be talking
about two different phases.

---Z01---+---Z02---

Vfor1--|--Vfor2

Vref1--|--Vref2

I am talking about the phase shift in the forward waves
across the impedance discontinuity, i.e. the phase shift
between Vfor1 and Vfor2. The list of phase shifts is
the phase shift in the forward voltages at the impedance
discontinuity. It is different for all the black boxes.

If you are talking about the phase between Vfor1 and Vref1,
then, yes, that phase is the same for all the black boxes.
It is impossible for it to be otherwise.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

On Sun, 16 Dec 2007 08:06:18 -0600, Cecil Moore
wrote:

2) 36.6 degrees? (previous answer when it was 10 degrees of 100 ohm
line)
3) 0 degrees? (previous answer when it was 46.6 degrees of 600 ohm
line)

There's nothing wrong with those answers except maybe
a stupid math error.

Stupid math errors must be valid answers then?

Loading Coils; was : Vincent antenna
 

On Sun, 16 Dec 2007 14:24:58 GMT, Cecil Moore
wrote:

It just occurred to me that you and I may be talking
about two different phases.

After weeks of this being explicitly stated by very many critics, it
just occurred to you?

Must be the onset of Netzheimers.

Loading Coils; was : Vincent antenna
 

Cecil Moore wrote:
Keith Dysart wrote:
So the next question is: What is the phase change
at the terminals of the black box?

It just occurred to me that you and I may be talking
about two different phases.

---Z01---+---Z02---

Vfor1--|--Vfor2

Vref1--|--Vref2

I am talking about the phase shift in the forward waves
across the impedance discontinuity, i.e. the phase shift
between Vfor1 and Vfor2. The list of phase shifts is
the phase shift in the forward voltages at the impedance
discontinuity. It is different for all the black boxes.

If you are talking about the phase between Vfor1 and Vref1,
then, yes, that phase is the same for all the black boxes.
It is impossible for it to be otherwise.

I think that Vfor1 and Vref1 could also be understood to mean Vfor1 and
Vrefsum, with Vrefsum being the sum of all the reflected waves occurring
within the black box.

It strikes me that the concept of steady state AC is no different from
the concept of DC discussed earlier in this thread. Steady state AC has
no wave front to analyze. The impedance at the black box junction is a
fact, not something that can be analyzed with steady state waves. I
think you have said this a number of times.

The standing wave has no velocity, because we can not define a unit of
the wave that moves. I think you have also pointed this out.

Wave fronts must be used if we want to look into the black box, or at
least a MOVING sine wave so that we can look at the first reflection
separately. I think this is what you have said many times, but I used
different words.

73, Roger, W7WKB

Loading Coils; was : Vincent antenna
 

Richard Clark wrote:
Cecil Moore wrote:
It just occurred to me that you and I may be talking
about two different phases.

After weeks of this being explicitly stated by very many critics, it
just occurred to you?

If it was ever stated, I missed it. I suspect it was never
stated and some people jumped to false conclusions. I don't
think anyone is stupid enough to assert that the phase shift
in a capacitor is the same as it is in the absence of any
physical impedance discontinuity.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Cecil Moore wrote:
Keith Dysart wrote:
So the next question is: What is the phase change
at the terminals of the black box?

It just occurred to me that you and I may be talking
about two different phases.

---Z01---+---Z02---

Vfor1--|--Vfor2

Vref1--|--Vref2

Continuing: What is the phase shift between Vfor1 and
Vfor2 for example:
(1) a capacitor with -j567 ohms impedance
(2) a 600 to 100 ohm dual-Z0 stub
(3) a single 600 ohm stub

I hope you are not going to tell us it's the same in
each case.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

On Sun, 16 Dec 2007 19:12:50 GMT, Cecil Moore
wrote:

I don't
think anyone is stupid enough to assert that the phase shift
in a capacitor is the same as it is in the absence of any
physical impedance discontinuity.

Capacitance is not obtained in a physical impedance discontinuity?
or is it:
Physical impedance discontinuity is not obtained from a capacitor?
or is it:
Could be either is inside a box, supplying only the terminals to
either; specifically either of which is indeterminate at a single
frequency where the terminals might present 43.4 degrees? (or any
suitable angle)

There are any number of stupid choices available. The question is:
Has your netzheimers progressed so far as to add another one?

At 800 postings, the odds must be distinctly favoring stupid.

Make it the daily-double:
Does a stupid math error make the answer valid?

Loading Coils; was : Vincent antenna
 

On Sun, 16 Dec 2007 19:17:48 GMT, Cecil Moore
wrote:

Cecil Moore wrote:
It just occurred to me that you and I may be talking
about two different phases.
Continuing: What is the phase shift

When you acknowledge there is some confusion as to which phase is
being talked about. Do you suppose you know enough to tell us which
phase you are talking about?

More to the matter, what TWO phases do you suppose there are to be
confused between?

At 800+ postings, you could continue to sail right on past these
questions in your cloud of netzheimer bliss and leave us with a 50%
risk -um- chance; answer your challenge; and watching you trying to
sort it out. Again.

Loading Coils; was : Vincent antenna
 

Richard Clark wrote:
Cecil Moore wrote:
I don't
think anyone is stupid enough to assert that the phase shift
in a capacitor is the same as it is in the absence of any
physical impedance discontinuity.

Capacitance is not obtained in a physical impedance discontinuity?
or is it:

You missed the point. A terminating capacitor is a two
terminal network. The point where two pieces of feedline
are connected is a four-terminal network. A two-terminal
network is different from a four-terminal network.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Richard Clark wrote:
On Sun, 16 Dec 2007 19:17:48 GMT, Cecil Moore
wrote:

Cecil Moore wrote:
It just occurred to me that you and I may be talking
about two different phases.
Continuing: What is the phase shift

When you acknowledge there is some confusion as to which phase is
being talked about. Do you suppose you know enough to tell us which
phase you are talking about?

Funny. In the part you deleated, I said it was the phase
shift between Vfor1 and Vfor2. Your sneaky underhanded
deletion trick is noted.
--
73, Cecil http://www.w5dxp.com