Loading Coils; was : Vincent antenna
 

Cecil Moore wrote:
I have *NEVER* said "power is moving", at least not in this
century.

Do you imagine that the caviat "not in this century" might make the
statement at least partially true?

That is just your straw man raising its ugly head
yet once again.

Was it not raised when you brought the definition of 'transfer' back
into the discussion - again this century?

ac6xg

Loading Coils; was : Vincent antenna
 

Jim Kelley wrote:
Cecil Moore wrote:
I have *NEVER* said "power is moving", at least not in this
century.

Do you imagine that the caviat "not in this century" might make the
statement at least partially true?

In the 20th century, I did believe in power flow but you
convinced me that I was wrong and I changed my mind. I
have not believed in power flow during the 21st century.


That is just your straw man raising its ugly head
yet once again.

Was it not raised when you brought the definition of 'transfer' back
into the discussion - again this century?

I will keep bringing it up until you furnish the definition
that you are using for the word. That you absolutely refuse
to provide a definition means it is nothing but your gut
feeling about the matter.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Richard Clark wrote:
On Thu, 13 Dec 2007 08:40:53 -0800, Roger wrote:


And just for completeness...
The fundamental equations also work when:
- the signal is not sinusoidal, e.g. pulse, step, square, ...
- rather than a load at one end, there is a source at each end
- the sources at each end produce different arbitrary functions
- the arbitrary functions at each end are DC sources
It is highly instructive to compute the forward and reverse
voltage and current (and then power) for a line with the same
DC voltage applied to each end.

...Keith

...Keith


Interesting! The important thing is to get answers that agree with
our experiments.

I have done some computations for DC voltage applied to transmission
lines. The real surprise for me came when I realized that transmission
line impedance could be expressed as a function of capacitance and the
wave velocity. Z0 = 1/cC where c is the velocity of the wave and C is
the capacitance of the transmission line per unit length.


Hi Roger,

This last round has piqued my interest when we dipped into DC. Those
"formulas" would lead us to a DC wave velocity?

73's
Richard Clark, KB7QHC

Hi Richard,

Here are two links to pages that cover the derivation of the formula Zo
= 1/cC and much more.

http://www.speedingedge.com/PDF-File..._Impedance.pdf
http://www.ece.uci.edu/docs/hspice/h...001_2-269.html

Here is the way I proposed to Kevin Schmidt nearly seven years ago after
seeing him use the formula on a web page:

*ASSUME*:
1) An electrical wave travels at the speed of light, c
2) A 'perfect' voltage source without impedance, V
3) A 'perfect' transmission line having no resistance but uniform
capacitance per unit length, C

*CONDITIONS AND SOLUTION*
The perfect voltage source has one terminal connected to the
transmission line prior to beginning the experiment. The experiment
begins by connecting the second terminal to the transmission line. The
voltage source drives an electrical wave down the transmission line at
the speed of light. Because of the limitation of speed, the wave
travels in the shape of a square wave containing all frequencies
required to create a square wave.

The square wave travels down the transmission line at the speed of light
(c). After time (T), the wave has traveled distance cT down the
transmission line, and has charged the distributed capacity CcT of the
line to voltage V over that distance. The total charge Q on the
distributed capacitor is VCcT.

Current (I) is expressed as charge Q per unit time. Therefore the
current into the transmission line can be expressed as

I = Q/T =
VCcT / T = VCc

Impedance (Zo) is the ratio of voltage (V) to current (I). Therefore
the impedance can be expressed as

Zo = V / I =
V / VCc = 1/Cc

We can generalize this by using the velocity of the electrical wave
rather than the speed of light, which allows the formula to be applied
to transmission line with velocities slower than the speed of light.

Of course, only the wave front and wave end of a DC wave can be
measured to have a velocity.

73, Roger, W7WKB

Loading Coils; was : Vincent antenna
 

In a 231 line posting that contains only original 57 lines:
On Thu, 13 Dec 2007 17:26:17 -0800, Roger 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?

Hi Richard,

Here are two links to pages that cover the derivation of the formula Zo
= 1/cC and much more.

http://www.speedingedge.com/PDF-File..._Impedance.pdf
http://www.ece.uci.edu/docs/hspice/h...001_2-269.html

Here is the way I proposed to Kevin Schmidt nearly seven years ago after
seeing him use the formula on a web page:

Hi Roger,

However, none of what you respond with actually gives a DC wave
velocity. At a stretch, it is a transient with the potential of an
infinite number of waves (which could suffer dispersion from the
line's frequency characteristics making for an infinite number of
velocities). The infinite is a trivial observation in the scheme of
things when we return to DC.

Attaching a battery casts it into a role of AC generation (for however
long the transmission line takes to settle to an irresolvable
ringing). Discarding the term DC returns us to conventional
transmission line mechanics.

DC, in and of itself, has no wave velocity.

HTML enhanced text didn't help either. Some may shrug this off, but
browsers are the vectors of internet virii.

73's
Richard Clark, KB7QHC

Loading Coils; was : Vincent antenna
 

"Roger" wrote in message
. ..
Richard Clark wrote:
On Thu, 13 Dec 2007 08:40:53 -0800, Roger wrote:


And just for completeness...
The fundamental equations also work when:
- the signal is not sinusoidal, e.g. pulse, step, square, ...
- rather than a load at one end, there is a source at each end
- the sources at each end produce different arbitrary functions
- the arbitrary functions at each end are DC sources
It is highly instructive to compute the forward and reverse
voltage and current (and then power) for a line with the same
DC voltage applied to each end.

...Keith

...Keith


Interesting! The important thing is to get answers that agree with
our experiments.

I have done some computations for DC voltage applied to transmission
lines. The real surprise for me came when I realized that transmission
line impedance could be expressed as a function of capacitance and the
wave velocity. Z0 = 1/cC where c is the velocity of the wave and C is
the capacitance of the transmission line per unit length.


Hi Roger,

This last round has piqued my interest when we dipped into DC. Those
"formulas" would lead us to a DC wave velocity?

73's
Richard Clark, KB7QHC

Hi Richard,

Here are two links to pages that cover the derivation of the formula Zo
= 1/cC and much more.

http://www.speedingedge.com/PDF-File..._Impedance.pdf
http://www.ece.uci.edu/docs/hspice/h...001_2-269.html

Here is the way I proposed to Kevin Schmidt nearly seven years ago after
seeing him use the formula on a web page:

*ASSUME*:
1) An electrical wave travels at the speed of light, c
2) A 'perfect' voltage source without impedance, V
3) A 'perfect' transmission line having no resistance but uniform
capacitance per unit length, C

*CONDITIONS AND SOLUTION*
The perfect voltage source has one terminal connected to the
transmission line prior to beginning the experiment. The experiment
begins by connecting the second terminal to the transmission line. The
voltage source drives an electrical wave down the transmission line at
the speed of light. Because of the limitation of speed, the wave
travels in the shape of a square wave containing all frequencies
required to create a square wave.

The square wave travels down the transmission line at the speed of light
(c). After time (T), the wave has traveled distance cT down the
transmission line, and has charged the distributed capacity CcT of the
line to voltage V over that distance. The total charge Q on the
distributed capacitor is VCcT.

Current (I) is expressed as charge Q per unit time. Therefore the
current into the transmission line can be expressed as

I = Q/T =
VCcT / T = VCc

Impedance (Zo) is the ratio of voltage (V) to current (I). Therefore
the impedance can be expressed as

Zo = V / I =
V / VCc = 1/Cc

We can generalize this by using the velocity of the electrical wave
rather than the speed of light, which allows the formula to be applied
to transmission line with velocities slower than the speed of light.

Of course, only the wave front and wave end of a DC wave can be
measured to have a velocity.

73, Roger, W7WKB

the OBVIOUS error is that the step when the second terminal is connected
DOES NOT travel down the line at c, it travels at some smaller percentage of
c given by the velocity factor of the line.

The second OBVIOUS error is the terminology 'DC wave'. you are measuring
the propagation velocity of a step function. this is a well defined fields
and waves 101 homework problem, not to be confused with the much more common
'sinusoidal stead state' solution that most other arguments on this group
assume but don't understand.

Loading Coils; was : Vincent antenna
 

"Dave" wrote in message
news:q7u8j.6941$xd.2942@trndny03...

"Roger" wrote in message
. ..
Richard Clark wrote:
On Thu, 13 Dec 2007 08:40:53 -0800, Roger wrote:


And just for completeness...
The fundamental equations also work when:
- the signal is not sinusoidal, e.g. pulse, step, square, ...
- rather than a load at one end, there is a source at each end
- the sources at each end produce different arbitrary functions
- the arbitrary functions at each end are DC sources
It is highly instructive to compute the forward and reverse
voltage and current (and then power) for a line with the same
DC voltage applied to each end.

...Keith

...Keith


Interesting! The important thing is to get answers that agree with
our experiments.

I have done some computations for DC voltage applied to transmission
lines. The real surprise for me came when I realized that
transmission
line impedance could be expressed as a function of capacitance and the
wave velocity. Z0 = 1/cC where c is the velocity of the wave and C
is
the capacitance of the transmission line per unit length.


Hi Roger,

This last round has piqued my interest when we dipped into DC. Those
"formulas" would lead us to a DC wave velocity?

73's
Richard Clark, KB7QHC

Hi Richard,

Here are two links to pages that cover the derivation of the formula Zo
= 1/cC and much more.

http://www.speedingedge.com/PDF-File..._Impedance.pdf
http://www.ece.uci.edu/docs/hspice/h...001_2-269.html

Here is the way I proposed to Kevin Schmidt nearly seven years ago after
seeing him use the formula on a web page:

*ASSUME*:
1) An electrical wave travels at the speed of light, c
2) A 'perfect' voltage source without impedance, V
3) A 'perfect' transmission line having no resistance but uniform
capacitance per unit length, C

*CONDITIONS AND SOLUTION*
The perfect voltage source has one terminal connected to the
transmission line prior to beginning the experiment. The experiment
begins by connecting the second terminal to the transmission line. The
voltage source drives an electrical wave down the transmission line at
the speed of light. Because of the limitation of speed, the wave
travels in the shape of a square wave containing all frequencies
required to create a square wave.

The square wave travels down the transmission line at the speed of light
(c). After time (T), the wave has traveled distance cT down the
transmission line, and has charged the distributed capacity CcT of the
line to voltage V over that distance. The total charge Q on the
distributed capacitor is VCcT.

Current (I) is expressed as charge Q per unit time. Therefore the
current into the transmission line can be expressed as

I = Q/T =
VCcT / T = VCc

Impedance (Zo) is the ratio of voltage (V) to current (I). Therefore
the impedance can be expressed as

Zo = V / I =
V / VCc = 1/Cc

We can generalize this by using the velocity of the electrical wave
rather than the speed of light, which allows the formula to be applied
to transmission line with velocities slower than the speed of light.

Of course, only the wave front and wave end of a DC wave can be
measured to have a velocity.

73, Roger, W7WKB

the OBVIOUS error is that the step when the second terminal is connected
DOES NOT travel down the line at c, it travels at some smaller percentage
of c given by the velocity factor of the line.

That IS what I said. Think of the velocity as a moving wall, with the
capacitor charged behind the wall, uncharged in front of the moving wall.

The second OBVIOUS error is the terminology 'DC wave'. you are measuring
the propagation velocity of a step function. this is a well defined
fields and waves 101 homework problem, not to be confused with the much
more common 'sinusoidal stead state' solution that most other arguments on
this group assume but don't understand.



Be real. This experiment can be performed, and the DC switched as
frequently as desired. How square the wave front will be depends upon real
world factors.

Go to a transmission line characteristics table and use the formula to
compare Zo, capacity per length, and line velocity. It will amaze you.

73, Roger, W7WKB

Loading Coils; was : Vincent antenna
 

AI4QJ wrote:
"Richard Clark" wrote in message
...
In a 231 line posting that contains only original 57 lines:
On Thu, 13 Dec 2007 17:26:17 -0800, Roger 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?
Hi Richard,

Here are two links to pages that cover the derivation of the formula Zo
= 1/cC and much more.

http://www.speedingedge.com/PDF-File..._Impedance.pdf
http://www.ece.uci.edu/docs/hspice/h...001_2-269.html

Here is the way I proposed to Kevin Schmidt nearly seven years ago after
seeing him use the formula on a web page:
Hi Roger,

However, none of what you respond with actually gives a DC wave
velocity. At a stretch, it is a transient with the potential of an
infinite number of waves (which could suffer dispersion from the
line's frequency characteristics making for an infinite number of
velocities). The infinite is a trivial observation in the scheme of
things when we return to DC.

Attaching a battery casts it into a role of AC generation (for however
long the transmission line takes to settle to an irresolvable
ringing). Discarding the term DC returns us to conventional
transmission line mechanics.

DC, in and of itself, has no wave velocity.

For the model provided, R= 0, therefore we have a transmission line
consisting of superconductors. The speed at which steady state DC current is
injected into the model will equal the maximum speed of DC current in the
model. Although the electrons themselves will move very slowly, for each
coulomb injected in, one coulomb will be injected out at the same velocity
they were injected in (not to be confused with 'current' which is the number
of coulombs per second). If it were possible for the source to provide DC
current at c, then the DC current moves at c. The capacitance C can be any
value and Zo has no meaning. The only model that works here is the one with
a cardboard tube filled with ping pong balls, in this case with 0 distance
between them.

Ah, but of so little importance because the model is not reality.


While R (ohmic resistance) is specified as zero, impedance is what we
are looking for. Impedance is the ratio of voltage to current.

So far as we know, the maximum velocity permitted in the universe is the
speed of light, which is the speed of electromagnetic disturbance. Here
we disturb the transmission line electromagnetically. Think of the
velocity of the wave front as a moving wall. Everything behind the
moving wall is charged to the applied voltage, everything in front is
uncharged. The ratio of voltage to current turns out to be a pure
resistance, dependent only on the capacity per length and wave velocity.

Before becoming too critical or skeptical, run the equation with the
characteristics from a few transmission lines. You will find that the
numbers are very close, but not exact. The published characteristics
are not carried out to many decimal places, and who knows to what
accuracy they were determined.

73, Roger, W7WKB

Loading Coils; was : Vincent antenna
 

AI4QJ wrote:
If it were possible for the source to provide DC
current at c, then the DC current moves at c.

The step function from zero to DC contains a lot
of frequencies. I suspect photons are involved
at the leading edge of the DC pulse.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

On Dec 14, 9:40 am, Cecil Moore wrote:
AI4QJ wrote:
If it were possible for the source to provide DC
current at c, then the DC current moves at c.

The step function from zero to DC contains a lot
of frequencies. I suspect photons are involved
at the leading edge of the DC pulse.

"Suspect" -- Perhaps like Inspector Clouseau?

Humour aside, for transmission lines you should
stick to charge, and distributed capacitance and
inductance. This model is aptly capable and has
no difficulties as the frequency drops so low that
it becomes indistinguishable from DC.

Why bother with photons? Only at the leading
edge, you say. What explains the rest?

Where is the energy stored? In the capacitance
and inductance. Why not use the tools that work?

Why try to force fit photons?

....Keith

Loading Coils; was : Vincent antenna
 

Keith Dysart wrote:
Why bother with photons?

Because it is impossible for electrons to move
fast enough to explain the measured results.
There is indeed a "DC" *wavefront* moving at
the speed of light adjusted for VF. Electrons
cannot move that fast. What is happening is
that fast photons are skipping from slow electron
to slow electron.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

On Fri, 14 Dec 2007 05:18:03 -0800, "Roger Sparks"
wrote:

That IS what I said. Think of the velocity as a moving wall, with the
capacitor charged behind the wall, uncharged in front of the moving wall.
....
Be real. This experiment can be performed, and the DC switched as
frequently as desired. How square the wave front will be depends upon real
world factors.

Go to a transmission line characteristics table and use the formula to
compare Zo, capacity per length, and line velocity. It will amaze you.

Hi Roger,

Take a deep breath, exhale, give what's above some more thought in
light of many objections.

Now, tells us just what significance any of this has in relation to
already well established line mechanics? It certainly isn't different
within the confines of its limitations if that is what you are trying
to impress upon the group. I suppose for a mental short-cut it has
some appeal, we get too many theories here based on approximations to
stricter math. One such example is when an equation of approximation
has forgotten the underlying |absolute value| and suddenly an inventor
arrives with a "new" theory that discovers uses for negative
solutions.

Further, there is nothing DC about it at all. DC is either static
(and in spite of Arthur's corruption of the term, that means no
movement whatever) or it is a constant unvarying current. A
succession of distributed capacitors rules unvarying current out (and
if it isn't already obvious, those unmentioned distributed inductors
in one of your links do too) - hence the step, hence the infinity of
waves, and from this, real world dispersion which kills the step
enough to make that varying current apparent enough so as to remove
all doubt.

73's
Richard Clark, KB7QHC

Loading Coils; was : Vincent antenna
 

Keith Dysart wrote:
On Dec 14, 9:40 am, Cecil Moore wrote:
AI4QJ wrote:
If it were possible for the source to provide DC
current at c, then the DC current moves at c.
The step function from zero to DC contains a lot
of frequencies. I suspect photons are involved
at the leading edge of the DC pulse.

"Suspect" -- Perhaps like Inspector Clouseau?

Humour aside, for transmission lines you should
stick to charge, and distributed capacitance and
inductance. This model is aptly capable and has
no difficulties as the frequency drops so low that
it becomes indistinguishable from DC.

Why bother with photons? Only at the leading
edge, you say. What explains the rest?

Where is the energy stored? In the capacitance
and inductance. Why not use the tools that work?

Why try to force fit photons?

....Keith

If we look at a tree from the north side, and then look at the same tree
from the south side, we have looked at only one tree but we have seen it
from two perspectives.

Zo = sq. rt. L/C = 1/cC

Inductance can be described as L = 1/((c^2)*C) (inductance per length)

So is the energy stored in the inductance or in the capacitance.

Two ways of looking at the same tree.

73, Roger, W7WKB

Loading Coils; was : Vincent antenna
 

Richard Clark wrote:
On Fri, 14 Dec 2007 05:18:03 -0800, "Roger Sparks"
wrote:

That IS what I said. Think of the velocity as a moving wall, with the
capacitor charged behind the wall, uncharged in front of the moving wall.
....
Be real. This experiment can be performed, and the DC switched as
frequently as desired. How square the wave front will be depends upon real
world factors.

Go to a transmission line characteristics table and use the formula to
compare Zo, capacity per length, and line velocity. It will amaze you.

Hi Roger,

Take a deep breath, exhale, give what's above some more thought in
light of many objections.

Now, tells us just what significance any of this has in relation to
already well established line mechanics? It certainly isn't different
within the confines of its limitations if that is what you are trying
to impress upon the group. I suppose for a mental short-cut it has
some appeal, we get too many theories here based on approximations to
stricter math. One such example is when an equation of approximation
has forgotten the underlying |absolute value| and suddenly an inventor
arrives with a "new" theory that discovers uses for negative
solutions.

Further, there is nothing DC about it at all. DC is either static
(and in spite of Arthur's corruption of the term, that means no
movement whatever) or it is a constant unvarying current. A
succession of distributed capacitors rules unvarying current out (and
if it isn't already obvious, those unmentioned distributed inductors
in one of your links do too) - hence the step, hence the infinity of
waves, and from this, real world dispersion which kills the step
enough to make that varying current apparent enough so as to remove
all doubt.

73's
Richard Clark, KB7QHC

Hi Richard,

The math seems to work, but if you have no use for it, disregard it. On
the other hand, if another perspective of electro magnetics that
conforms to traditional mathematics can provide additional insight, use it.

I am surprised at your criticism in using DC. To me, a square wave is
DC for a short time period. Is the observation that a square wave can
be described as a series of sine waves troubling to you? Perhaps the
observation that a square wave might include waves of a frequency so
high that they would not be confined in a normal transmission line is
surprising or troubling to you?

My goal is to better understand electromagnetic phenomena. You have
given some very astute insight many times in the past and thanks for
that. Negative comment is equally valuable, but sometimes a little
harder to swallow.

73, Roger, W7WKB

Loading Coils; was : Vincent antenna
 

On Dec 14, 9:40 am, Cecil Moore wrote:
AI4QJwrote:
If it were possible for the source to provide DC
current at c, then the DC current moves at c.

The step function from zero to DC contains a lot
of frequencies. I suspect photons are involved
at the leading edge of the DC pulse.
--
73, Cecil http://www.w5dxp.com

Right, the step function has a number of sinusoids associated with it
which are affected by Zo and that was already addressed. Richard's
challenge was to address the velocity of DC at steady state, after the
transients from the step died down.

Loading Coils; was : Vincent antenna
 

On Fri, 14 Dec 2007 09:45:04 -0800, Roger wrote:

Hi Richard,

The math seems to work, but if you have no use for it, disregard it. On
the other hand, if another perspective of electro magnetics that
conforms to traditional mathematics can provide additional insight, use it.

Hi Roger,

This does not answer why TWO mathematics (both traditional) are
needed, especially since one is clearly an approximation of the other,
and yet offers no obvious advantage. I've already spoken to the
hazards of approximations being elevated to proof by well-meaning, but
slightly talented amateurs.

I am surprised at your criticism in using DC. To me, a square wave is
DC for a short time period.

This single statement, alone, is enough to be self-negating. You
could as easily call a car with a standard stick shift an automatic
between the times you use the clutch - but that won't sell cars, will
it?

Is the observation that a square wave can
be described as a series of sine waves troubling to you? Perhaps the
observation that a square wave might include waves of a frequency so
high that they would not be confined in a normal transmission line is
surprising or troubling to you?

DC as sine waves is not a contradiction on the face of it? DC that
consists of waves of a frequency so high that it would not be confined
in a normal transmission line is very surprising, isn't it?

Would it surprise you to find your batteries in their packaging direct
from the store are radiating on the shelf? They are DC, are they not?
If the arguments of your sources works for an infinite line, they must
be equally true for an infinitesimal open line. When your headlights
are on, do they set off radar detectors in cars nearby because of the
high frequencies now associated with DC?

My goal is to better understand electromagnetic phenomena. You have
given some very astute insight many times in the past and thanks for
that. Negative comment is equally valuable, but sometimes a little
harder to swallow.

The pollution of terms such as DC to serve a metaphor that replaces
conventional line mechanics is too shallow glass to attempt to quench
any thirst.

The puzzle here is the insistence on hugging DC, when every element of
all of your links could as easily substitute Stepped Wave and remove
objections. The snake in the wood pile is once having fudged what DC
means, it is only a sideways argument away from rendering the term DC
useless. Is the term Stepped Wave (the convention) anathema for a
leveraging the novel origination (the invention) of DC Wave?

73's
Richard Clark, KB7QHC

Loading Coils; was : Vincent antenna
 

On Dec 14, 11:10 am, Cecil Moore wrote:
Keith Dysart wrote:
Why bother with photons?

Because it is impossible for electrons to move
fast enough to explain the measured results.
There is indeed a "DC" *wavefront* moving at
the speed of light adjusted for VF. Electrons
cannot move that fast. What is happening is
that fast photons are skipping from slow electron
to slow electron.

Do photons also explain how sound can move
at a 1000 ft/s, while the air molecules barely
move at all?

No? Not clear then why they are needed for
electrons.

....Keith

Loading Coils; was : Vincent antenna
 

Roger wrote:
I am surprised at your criticism in using DC. To me, a square wave is
DC for a short time period. Is the observation that a square wave can
be described as a series of sine waves troubling to you? Perhaps the
observation that a square wave might include waves of a frequency so
high that they would not be confined in a normal transmission line is
surprising or troubling to you?

Anyone who has ever tried to send a DC pulse down a long
transmission line has seen AC ringing at the other end.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

wrote:
Right, the step function has a number of sinusoids associated with it
which are affected by Zo and that was already addressed. Richard's
challenge was to address the velocity of DC at steady state, after the
transients from the step died down.

Another steady-state Catch-22, one of many.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Richard Clark wrote:
The puzzle here is the insistence on hugging DC, when every element of
all of your links could as easily substitute Stepped Wave and remove
objections.

How about "continuous wave" for Morse code?
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Keith Dysart wrote:
Do photons also explain how sound can move
at a 1000 ft/s, while the air molecules barely
move at all?

No, mechanical longitudinal waves are well understood.
It is impossible for them to achieve the speed of light.

No? Not clear then why they are needed for
electrons.

Do you think electrons support mechanical waves?
The fields of TEM waves consist of photons traveling
at the speed of light.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

Richard Clark wrote:
On Fri, 14 Dec 2007 09:45:04 -0800, Roger wrote:

Hi Richard,

The math seems to work, but if you have no use for it, disregard it. On
the other hand, if another perspective of electro magnetics that
conforms to traditional mathematics can provide additional insight, use it.

Hi Roger,

This does not answer why TWO mathematics (both traditional) are
needed, especially since one is clearly an approximation of the other,
and yet offers no obvious advantage. I've already spoken to the
hazards of approximations being elevated to proof by well-meaning, but
slightly talented amateurs.

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, 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.

I am surprised at your criticism in using DC. To me, a square wave is
DC for a short time period.

This single statement, alone, is enough to be self-negating. You
could as easily call a car with a standard stick shift an automatic
between the times you use the clutch - but that won't sell cars, will
it?

We could use the concept of a stepped wave, but that would imply the
need for several steps to develop the formula. Only the square wave
front and continued charge maintenance is required, observations that
can be easily verified by experiment.

Is the observation that a square wave can
be described as a series of sine waves troubling to you? Perhaps the
observation that a square wave might include waves of a frequency so
high that they would not be confined in a normal transmission line is
surprising or troubling to you?

DC as sine waves is not a contradiction on the face of it? DC that
consists of waves of a frequency so high that it would not be confined
in a normal transmission line is very surprising, isn't it?


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. This leads Cecil to comment that the leading edge of a square
wave could be composed of photons, which is a valid observation. It
also explains your observation that true square waves are not possible
(I am paraphrasing your comments) because of dispersion.

It is interesting to run an FFT on a square wave to see how the
frequencies can be resolved.

Would it surprise you to find your batteries in their packaging direct
from the store are radiating on the shelf? They are DC, are they not?
If the arguments of your sources works for an infinite line, they must
be equally true for an infinitesimal open line. When your headlights
are on, do they set off radar detectors in cars nearby because of the
high frequencies now associated with DC?

They only set off the radar detectors when I turn them on and off. I
have high power lights!! A lightning strike is a much better example of
DC containing high frequencies.


My goal is to better understand electromagnetic phenomena. You have
given some very astute insight many times in the past and thanks for
that. Negative comment is equally valuable, but sometimes a little
harder to swallow.

The pollution of terms such as DC to serve a metaphor that replaces
conventional line mechanics is too shallow glass to attempt to quench
any thirst.

The puzzle here is the insistence on hugging DC, when every element of
all of your links could as easily substitute Stepped Wave and remove
objections. The snake in the wood pile is once having fudged what DC
means, it is only a sideways argument away from rendering the term DC
useless. Is the term Stepped Wave (the convention) anathema for a
leveraging the novel origination (the invention) of DC Wave?

73's
Richard Clark, KB7QHC

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

Is there some harm in considering Zo = 1/cC? It should only add to the
tools we have to explain electromagnetic waves.

73, Roger, W7WKB

Loading Coils; was : Vincent antenna
 

On Fri, 14 Dec 2007 10:09:59 -0800 (PST), Keith Dysart
wrote:

Do photons also explain how sound can move
at a 1000 ft/s, while the air molecules barely
move at all?

No, because those are called Phonons.

No? Not clear then why they are needed for
electrons.

Phonons and Photons both interact with Electrons as well as with each
other.

Following Cecil's fluff isn't very productive.

73's
Richard Clark, KB7QHC

Loading Coils; was : Vincent antenna
 

This general discussion sounds a lot like a description of a traditional
TDR system using a step function. You should be able to find quite a bit
of information about this process on the web.

A number of relationships among delay, Z0, velocity factor, and L and C
per unit length are quite useful, and I've used them for many years. For
example, a transmission line which is short in terms of wavelength at
the highest frequency of interest (related to the rise time when dealing
with step functions) can often be modeled with reasonable accuracy as a
lumped L or pi network. The values of the lumped components can easily
be calculated from the equations relating delay, Z0, L per unit length,
and C per unit length.

Strictly speaking, DC describes only the condition when a steady value
has existed for an infinite length of time. But a frequency spectrum of
finite width also requires a signal which has been unchanging (except
for periodic variation) for an infinite time. In both cases, we can
approximate the condition with adequate accuracy without having to wait
an infinite length of time. In the case of a step response, we wait
until all the aberrations have settled, after which the response is for
practical purposes the DC response. People used to frequency domain
analysis having trouble with the concept of DC characteristics and
responses can often get around the difficulty by looking at DC as a
limiting case of low frequency.

I don't know if it's relevant to the discussion, but the velocity factor
of many transmission lines is a function of frequency. A classic example
is microstrip line, which exhibits this dispersive property because the
fractions of field in the air and dielectric changes with frequency.
Coaxial line, however, isn't dispersive (assuming that the dielectric
constant of the insulator doesn't change with frequency) because the
field is entirely in the dielectric. It will, therefore, exhibit a
constant velocity factor down to an arbitrarily low frequency -- to DC,
you might say. Waveguides, however, are generally dispersive for other
reasons despite the air dielectric. The shape of the step response of a
dispersive line is very distinctive, and is easily recognized by someone
accustomed to doing time domain analysis.

There seems to be a constant search on this newsgroup for amazing new
principles, and "discoveries" are constantly being made by
misinterpretation and partial understanding of very well established
principles. I sense that happening here. Anyone who's really interested
in gaining a deeper understanding of transmission line principles and
operation can benefit from a bit of study of time domain reflectometry
and other time domain applications. All the fundamental rules are
exactly the same, but the practical manifestations are different enough
that it can give you a whole new level of understanding.

Roy Lewallen, W7EL

Loading Coils; was : Vincent antenna
 

Is there some harm in considering Zo = 1/cC? It should only add to the
tools we have to explain electromagnetic waves.

73, Roger, W7WKB

yes. because its WRONG. you have made an assumption that is not realistic
for any transmission line. There is no way a transmission line can have a
velocity factor of 1.0, just can't happen... all the equations fall apart
and become meaningless at that point. there is a reason for the velocity
factor, or beta, depending on which you prefer. learn it, and use it
properly, and it will serve you well.

Loading Coils; was : Vincent antenna
 

Roy Lewallen wrote:
I don't know if it's relevant to the discussion, but the velocity factor
of many transmission lines is a function of frequency.

Dr. Corum's formulas indicate that the velocity factor
of large coils is also a function of frequency.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

"Roger" wrote in message
. ..

Is there some harm in considering Zo = 1/cC? It should only add to the
tools we have to explain electromagnetic waves.

73, Roger, W7WKB

yes. because its WRONG. you have made an assumption that is not realistic
for any transmission line. There is no way a transmission line can have a
velocity factor of 1.0, just can't happen... all the equations fall apart
and become meaningless at that point. there is a reason for the velocity
factor, or beta, depending on which you prefer. learn it, and use it
properly, and it will serve you well.

Loading Coils; was : Vincent antenna
 

AI4QJ wrote:
. . .
(I sure am learning a lot about antennas and transmission lines here)

I'm glad to hear that. 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?

Roy Lewallen, W7EL

Loading Coils; was : Vincent antenna
 

Cecil Moore wrote:

...
No, mechanical longitudinal waves are well understood.
...

Indeed, I wonder if there is really anything else ...

Although Einstein "debunked" (and, we may even have to revisit this at a
later date) the "luminous ether", he granted the existence of the
"gravitational ether", one way or another, how those em waves-photons
"propagate", they do it in some form of ether ...

Show me an equation which takes that into consideration--I will grant we
are finally close to the right path ...

Regards,
JS

Loading Coils; was : Vincent antenna
 

Roy Lewallen wrote:
I'm glad to hear that. 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?

Print s22 on each box and we won't even need to apply
power to the source.
--
73, Cecil http://www.w5dxp.com

Loading Coils; was : Vincent antenna
 

AI4QJ wrote:
"Roger" wrote in message
. ..
AI4QJ wrote:
"Richard Clark" wrote in message
...
In a 231 line posting that contains only original 57 lines:
On Thu, 13 Dec 2007 17:26:17 -0800, Roger 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?
Hi Richard,

Here are two links to pages that cover the derivation of the formula
Zo
= 1/cC and much more.

http://www.speedingedge.com/PDF-File..._Impedance.pdf
http://www.ece.uci.edu/docs/hspice/h...001_2-269.html

Here is the way I proposed to Kevin Schmidt nearly seven years ago
after
seeing him use the formula on a web page:
Hi Roger,

However, none of what you respond with actually gives a DC wave
velocity. At a stretch, it is a transient with the potential of an
infinite number of waves (which could suffer dispersion from the
line's frequency characteristics making for an infinite number of
velocities). The infinite is a trivial observation in the scheme of
things when we return to DC.

Attaching a battery casts it into a role of AC generation (for however
long the transmission line takes to settle to an irresolvable
ringing). Discarding the term DC returns us to conventional
transmission line mechanics.

DC, in and of itself, has no wave velocity.
For the model provided, R= 0, therefore we have a transmission line
consisting of superconductors. The speed at which steady state DC current
is injected into the model will equal the maximum speed of DC current in
the model. Although the electrons themselves will move very slowly, for
each coulomb injected in, one coulomb will be injected out at the same
velocity they were injected in (not to be confused with 'current' which
is the number of coulombs per second). If it were possible for the source
to provide DC current at c, then the DC current moves at c. The
capacitance C can be any value and Zo has no meaning. The only model that
works here is the one with a cardboard tube filled with ping pong balls,
in this case with 0 distance between them.

Ah, but of so little importance because the model is not reality.
While R (ohmic resistance) is specified as zero, impedance is what we are
looking for. Impedance is the ratio of voltage to current.

Roger the impedance is zero because the current is steady state DC. F = 0,

Zo = 0 -j*2*pi*0*C =0

It was already stated that we should ignore the wavefront of the step
function. What we are left with is steady state. So impedance is not what
'we' are looking for.

(I sure am learning a lot about antennas and transmission lines here)


Yes, I am learning a lot also.

Well, I did not say we should ignore the wave front, just the opposite.
The wave front gives us the time marker so that velocity has meaning
in relationship to a length of transmission line.

Roy is giving good advice to study time domain reflectometry. One
reference I looked at used different pulse widths to examine for faults
at different distances. That makes sense to me.

Where did you get the formula for Zo that resulted in a zero impedance?

73, Roger, W7WKB

Loading Coils; was : Vincent antenna
 

On Dec 14, 7:59 pm, "AI4QJ" wrote:
"Roger" wrote in message

. ..





AI4QJ wrote:
"Richard Clark" wrote in message
. ..
In a 231 line posting that contains only original 57 lines:
On Thu, 13 Dec 2007 17:26:17 -0800, Roger 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?
Hi Richard,

Here are two links to pages that cover the derivation of the formula
Zo
= 1/cC and much more.

http://www.speedingedge.com/PDF-File...stic_Impedance...
http://www.ece.uci.edu/docs/hspice/h...001_2-269.html

Here is the way I proposed to Kevin Schmidt nearly seven years ago
after
seeing him use the formula on a web page:
Hi Roger,

However, none of what you respond with actually gives a DC wave
velocity. At a stretch, it is a transient with the potential of an
infinite number of waves (which could suffer dispersion from the
line's frequency characteristics making for an infinite number of
velocities). The infinite is a trivial observation in the scheme of
things when we return to DC.

Attaching a battery casts it into a role of AC generation (for however
long the transmission line takes to settle to an irresolvable
ringing). Discarding the term DC returns us to conventional
transmission line mechanics.

DC, in and of itself, has no wave velocity.

For the model provided, R= 0, therefore we have a transmission line
consisting of superconductors. The speed at which steady state DC current
is injected into the model will equal the maximum speed of DC current in
the model. Although the electrons themselves will move very slowly, for
each coulomb injected in, one coulomb will be injected out at the same
velocity they were injected in (not to be confused with 'current' which
is the number of coulombs per second). If it were possible for the source
to provide DC current at c, then the DC current moves at c. The
capacitance C can be any value and Zo has no meaning. The only model that
works here is the one with a cardboard tube filled with ping pong balls,
in this case with 0 distance between them.

Ah, but of so little importance because the model is not reality.
While R (ohmic resistance) is specified as zero, impedance is what we are
looking for. Impedance is the ratio of voltage to current.

Roger the impedance is zero because the current is steady state DC. F = 0,

Zo = 0 -j*2*pi*0*C =0

I'd suggest that this is an inaccurate interpretation.
For an ideal line we have

Z0 = sqrt( L/C )
and
velocity = 1/sqrt( LC )

These are the fundamental equations based on the
charactistics (distributed L and C) of the line.

These equations can be manipulated to yield
Z0 = 1/(velocity * C)
and
Z0 = velocity * L

But Z0 continues to exist regardless of the signal
being applied.

Think of the "velocity" as the velocity at which a
perturbation to the signal propagates down the
line.

When you turn on the constant voltage, the step
propagates down the line at "velocity", when you
change the voltage, the new step propagates at
"velocity". Over any region of the line where
the signal has a constant amplitude, it will
be difficult to discern this "velocity" but on
other regions of the line where a change is
present, it will be possible.

So if there are no perturbations, the "velocity"
can not be observed, but it would a mistake
to think that it goes away (or that Z0 does).

....Keith

Loading Coils; was : Vincent antenna
 

On Dec 14, 9:10 pm, "AI4QJ" wrote:
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?

The original problem statement discused -j567 as
an impedance. This is implicitly frequency dependant.

The Smith chart is normalized for impedance
and frequency.

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.

....Keith

Loading Coils; was : Vincent antenna
 

On Dec 14, 10:00 pm, "AI4QJ" wrote:
"Keith Dysart" wrote in message

...

On Dec 14, 9:10 pm, "AI4QJ" wrote:
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?

The original problem statement discused -j567 as
an impedance. This is implicitly frequency dependant.

Not if I change the capacitance.

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

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?

Everything is done in terms of degrees along a wave.
This implicitly normalizes for frequency.

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.

In the example, -j567 was merely due to a phase change due to the abrupt
impedance discontinuity. You are the one who suggested putting things in
black boxes. I suppose you could devise ways to phase shifts due to -j567 in
black boxes but I will have to leave that to you since you are the one who
brought up the idea.

Several ways were mentioned for obtaining the -j567:
a capacitor, some length of 100 ohm line, a different
length of 600 ohm line. Regardless of how the -j567
impedance is obtained, the same input impedance
to the 600 ohm line results. And yet each appears
to have a different phase shift occurring at the terminals.

Putting things in black boxes is a thought experiment
which helps isolate which aspects are important.
Any box containing a circuit which produces -j567
at the terminals will result in exactly the same
impedance at the input to the 600 ohm line, so
clearly -j567 is important.

Is the "phase shift" at the discontinuity important
when the results can be determined without knowing
the value. In fact, the "phase shift", in all the
examples, was computed last, after all the results
were known. How important can it be?

Do you suggest that there is no phase shift?

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.

Then how do you explain the smith chart results?

Starting with the 100 ohm line, the normalized
input impedance was computed using the Smith
chart. This impedance was denormalized and then
renormalized to the 600 ohm. The new value was
plotted on a new Smith chart (the chart normalized
to 600 ohms) and the length of the 600 ohm line
was determined. The two lines have lengths, call
them Z1len and Z2len. 90 - (Z1len + Z2len) will
give a number which Cecil/you have called the
"phase shift" at the discontinuity. Alternatively,
it is just what happens when -j567 is attached
to the appropriate length of 600 ohm line.

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?

I suggest that there is no need to refuse
since the only information that is required
is -j567. Whether the box achieves this with
600 ohm line ("no phase shift"), 100 ohm
line ("some phase shift"), a capacitor or
some other technique is irrelevant.

....Keith

Loading Coils; was : Vincent antenna
 

AI4QJ wrote:
"Roy Lewallen" wrote in message
...
AI4QJ wrote:
. . .
(I sure am learning a lot about antennas and transmission lines here)
I'm glad to hear that. 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?

Roy Lewallen, W7EL

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?

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?

The fourth box was my proposal, a box containing a capacitor with the
same reactance as the contents of the other boxes, and which I claimed
couldn't be distinguished from the others.

Roy Lewallen, W7EL

Loading Coils; was : Vincent antenna
 

AI4QJ wrote:

I also eventually agreed that I went too far to suggest one *could* tell the
differences. I could go back and find the post where I made that retraction
but it might take some time. It was a 'by the way' sort of thing; it seemed
to be almost corroborative but it was definitely was incorrect although not
very important in the overall discussion. Thank you for having corrected me
before. I thought I previously had submitted to the lashes of the whoop
haung (or whatever they call that thing at ARRL that you use to punish
hams).

Thanks, I had missed that posting. Did you also conclude, then, that all
the boxes contain the same number of "electrical degrees"?

Roy Lewallen, W7EL

Loading Coils; was : Vincent antenna
 

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?

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?

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 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.

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?

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

This is best left in the privacy of the home.

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

Loading Coils; was : Vincent antenna
 

"AI4QJ" wrote in message
...

"Roger" wrote in message
. ..
AI4QJ wrote:
"Richard Clark" wrote in message
...
In a 231 line posting that contains only original 57 lines:
On Thu, 13 Dec 2007 17:26:17 -0800, Roger 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?
Hi Richard,

Here are two links to pages that cover the derivation of the formula
Zo
= 1/cC and much more.

http://www.speedingedge.com/PDF-File..._Impedance.pdf
http://www.ece.uci.edu/docs/hspice/h...001_2-269.html

Here is the way I proposed to Kevin Schmidt nearly seven years ago
after
seeing him use the formula on a web page:
Hi Roger,

However, none of what you respond with actually gives a DC wave
velocity. At a stretch, it is a transient with the potential of an
infinite number of waves (which could suffer dispersion from the
line's frequency characteristics making for an infinite number of
velocities). The infinite is a trivial observation in the scheme of
things when we return to DC.

Attaching a battery casts it into a role of AC generation (for however
long the transmission line takes to settle to an irresolvable
ringing). Discarding the term DC returns us to conventional
transmission line mechanics.

DC, in and of itself, has no wave velocity.

For the model provided, R= 0, therefore we have a transmission line
consisting of superconductors. The speed at which steady state DC
current is injected into the model will equal the maximum speed of DC
current in the model. Although the electrons themselves will move very
slowly, for each coulomb injected in, one coulomb will be injected out
at the same velocity they were injected in (not to be confused with
'current' which is the number of coulombs per second). If it were
possible for the source to provide DC current at c, then the DC current
moves at c. The capacitance C can be any value and Zo has no meaning.
The only model that works here is the one with a cardboard tube filled
with ping pong balls, in this case with 0 distance between them.

Ah, but of so little importance because the model is not reality.
While R (ohmic resistance) is specified as zero, impedance is what we are
looking for. Impedance is the ratio of voltage to current.

Roger the impedance is zero because the current is steady state DC. F = 0,

Zo = 0 -j*2*pi*0*C =0

It was already stated that we should ignore the wavefront of the step
function. What we are left with is steady state. So impedance is not what
'we' are looking for.

(I sure am learning a lot about antennas and transmission lines here)

actually it is what you are looking for, you have just, again,
misinterpreted the results. in the DC case you have to remember that not
only is f=0, but wavelenght is infinite. so a shorted stub of any length of
transmission line appears to be 0% of a wavelength. using the normal
equations, or smith chart, to transform the impedance at the far end of the
line to the connection point will result in exactly the same impedance at
the connection point as is at the far end. so feed a DC current into a
shorted line of any length and in steady state you get infinite
current(assuming no loss in the line of course), use an open line and you
get zero current. put a resistive load out there and you see the load
resistance. it all works, you just have to know what to look for and just
what the conditions you have specified really mean.

as far as probing the 'black box' with varying frequencies or pulses to see
what is in it, you again must more clearly state the conditions. when it
was suggested that you could stick all the different circuits you used to
obtain the same impedance in a box and it was added to that a single
capacitor would look the same, the implicit assumption is that you are ONLY
going to examine the circuits in sinusoidal steady state at a single
frequency. that is the ONLY case where that type of replacement is valid.
if you allow transients or multiple frequencies than you can not substitute
a 'black box' for the unknown circuit. refer to any book from a circuits
101 course for the full analysis.

Loading Coils; was : Vincent antenna
 

On Dec 14, 1:52 pm, Cecil Moore wrote:
Keith Dysart wrote:
Do photons also explain how sound can move
at a 1000 ft/s, while the air molecules barely
move at all?

No, mechanical longitudinal waves are well understood.
It is impossible for them to achieve the speed of light.

Non-sequitor.

No? Not clear then why they are needed for
electrons.

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.

The fields of TEM waves consist of photons traveling
at the speed of light.

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? At what point? Where does the simply
varying field end and the photons begin? Or does
the antenna emit photons?

....Keith

Loading Coils; was : Vincent antenna
 

On Dec 14, 11:53 pm, "AI4QJ" wrote:
"Keith Dysart" wrote in message

...





On Dec 14, 10:00 pm, "AI4QJ" wrote:
"Keith Dysart" wrote in message

...

On Dec 14, 9:10 pm, "AI4QJ" wrote:
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?

The original problem statement discused -j567 as
an impedance. This is implicitly frequency dependant.

Not if I change the capacitance.

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

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?

Everything is done in terms of degrees along a wave.
This implicitly normalizes for frequency.

There is a specific recognized usage of the term "normalize" when referring
to a smith chart. It does not involve frequency.

Agreed. But I needed a word to capture the similar concept
for frequency so I chose "normalize". Feel free to propose
another, and possibly less confusing, word.

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.

In the example, -j567 was merely due to a phase change due to the abrupt
impedance discontinuity. You are the one who suggested putting things in
black boxes. I suppose you could devise ways to phase shifts due to -j567
in
black boxes but I will have to leave that to you since you are the one
who
brought up the idea.

Several ways were mentioned for obtaining the -j567:
a capacitor, some length of 100 ohm line, a different
length of 600 ohm line. Regardless of how the -j567
impedance is obtained, the same input impedance
to the 600 ohm line results. And yet each appears
to have a different phase shift occurring at the terminals.

Putting things in black boxes is a thought experiment
which helps isolate which aspects are important.
Any box containing a circuit which produces -j567
at the terminals will result in exactly the same
impedance at the input to the 600 ohm line, so
clearly -j567 is important.

Is the "phase shift" at the discontinuity important
when the results can be determined without knowing
the value. In fact, the "phase shift", in all the
examples, was computed last, after all the results
were known. How important can it be?

Do you suggest that there is no phase shift?

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 value is more obvious when applying the concept to a loaded whip
antenna.

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.

Then how do you explain the smith chart results?

Starting with the 100 ohm line, the normalized
input impedance was computed using the Smith
chart. This impedance was denormalized and then
renormalized to the 600 ohm. The new value was
plotted on a new Smith chart (the chart normalized
to 600 ohms) and the length of the 600 ohm line
was determined. The two lines have lengths, call
them Z1len and Z2len. 90 - (Z1len + Z2len) will
give a number which Cecil/you have called the
"phase shift" at the discontinuity. Alternatively,
it is just what happens when -j567 is attached
to the appropriate length of 600 ohm line.

But you have 10 degrees of 100 ohm line and you have 43 degrees of 600 ohm
line.

You also have resonance at 1/4W.

For 1/4W resonance you must have 90 degrees.

What happened to the missing 37 degrees?

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

If some do not care, then I agree that it is not important. It comes out of
a black box for all they care.

Others find it fascinating what nature does in order to keep following its
rules. I would never go through all the trouble to calculate this using math
but with the smith chart calculating for you, information like this jumps
out at you. When it does, many people yawn, others relate it to how antennas
with loading coils work and reveals one reason why Dr. Corum had to make
corrections for the true behavior of coils

Well I am not sure about the "true" nature of coils. 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. Corum thinks he can do better, but I doubt that even he
would claim that he has the "true" nature of such coils.

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?

....Keith

Loading Coils; was : Vincent antenna
 

"Keith Dysart" wrote in message
...
On Dec 14, 1:52 pm, Cecil Moore wrote:
Keith Dysart wrote:
Do photons also explain how sound can move
at a 1000 ft/s, while the air molecules barely
move at all?

No, mechanical longitudinal waves are well understood.
It is impossible for them to achieve the speed of light.

Non-sequitor.

No? Not clear then why they are needed for
electrons.

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.

The fields of TEM waves consist of photons traveling
at the speed of light.

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? At what point? Where does the simply
varying field end and the photons begin? Or does
the antenna emit photons?

...Keith

photons are a non-sequitar... or waves are, take your pick. but never the
twain shall meet... except in some odd quantum mechanics cases where waves
and photons are equally valid. For working with antennas at HF it is best
to forget photons, they will just confuse you. if you get into the inner
workings of lasers or BEC's or other quantum level effects then you might
need to use photons. EM fields and waves in the macro world are all that is
necessary to completely describe the solution to any problem you may
encounter in amateur radio. 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.