"K1TTT" wrote
...
On Jun 2, 2:12 pm, Cecil Moore wrote:

wave function solutions to maxwell's equations are enough to prove
that for me.

Not a loaded question: How do Maxwell's equations applied to a
standing wave prove that the component forward and reflected waves are
moving at the speed of light in the medium? If it can and if I can
understand it, I wouldn't need to use the photon argument.
--
73, Cecil, w5dxp.com

easy, maxwell's equations don't predict standing waves! they are a
product of superposition and the simplest instrumentation used since
they were first discovered.

"Kundt's tube is an experimental acoustical apparatus invented in 1866 by
German physicist August Kundt[1][2] for the measurement of the speed of
sound in a gas or a solid rod. It is used today only for demonstrating
standing waves and acoustical forces."

Heaviside wrote "Maxwell" equations" much later.

EM waves are the angular waves in the solid body. It would not be easy to
instal the mirror in such body.

You do not know that EM waves were stripped away in 1864.
The Maxwell's math is used in machinery to calculate the torsion vibration.
Maxwell predicted it:

"I propose now to examine magnetic phenomena from a mecha nical point of
view, and to determine what tensions in, or motions of, a medium are capable
of producing the mechanical pheno mena observed. If, by the same hypothesis,
we can connect the phenomena of magnetic attraction with electromagnetic
phenomena and with those of induced currents, we shall have found a theory
which, if not true, can only be proved to be erroneous by experiments which
will greatly enlarge our knowledge of this part of physics."

The hipothesis " be proved to be erroneous by experiments" but we have the
excelent math for thr solid body.
S*

"Cecil Moore" wrote
...
On Jun 2, 11:48 am, K1TTT wrote:
my differential calculus is a bit rusty, but i don't think that
equation satisfies the basic wave equation.

My calculus is probably a lot rustier than yours but it would be very
important for this discussion if Maxwell's equations do not work for
the standing wave equation. That would essentially prove that the
mashed-potatoes theory of transmission line energy is bogus.

Maxwell's equations are for angular waves in the solid body.
The transmission line and ends of it (antenna) are exactly like the Kundt's
tubes. In the wires is the electron gas.
S*

On 3 jun, 13:23, "Szczepan Bialek" wrote:
*"Cecil Moore" ...
On Jun 2, 11:48 am, K1TTT wrote:

my differential calculus is a bit rusty, but i don't think that
equation satisfies the basic wave equation.
My calculus is probably a lot rustier than yours but it would be very
important for this discussion if Maxwell's equations do not work for
the standing wave equation. That would essentially prove that the
mashed-potatoes theory of transmission line energy is bogus.

Maxwell's equations are for angular waves in the solid body.
The transmission line and ends of it (antenna) are exactly like the Kundt's
tubes. In the wires is the electron gas.
S*

Thanks to all

Hey boys! (Cecil, David, Michael, et al) It is very funny and
entertaining, I enjoy your postingss mostly in "read only" mode
because translate not simple mine ones still being a struggle for
me :-)
.....
Cecil, I never studied standing waves with Maxwell equations (except
in usual examples of cavity resonators cases learning classes), I
studied only classic electric differential solution to the
telegraper's equations.

Hi Keith: We tend to think of energy as a "tangible and real" easely
intuited thing "out there" (as a water or horses) but we must not
forget energy is a really elusive CONCEPT devised to explain changes
in physical systems. Familiarity tend us to fetishize concepts, then
we easily can get caught in troubles type = "Where velocity goes when
the car smash?" :-D :-D. We must be carefully with forces, powers,
velocities, etc. in this sense...
Note how Terman prudenty deals with differential solution of
Telegrapher's equations: "This combinatiosn of voltage and current can
be INTERPRETED as a wave train traveling toward receiver" (1)
(capitalized letters by me).

The very term "standing waves" leads to endless Ham controversies
about concept of "wave" word in our context.(wave as "a disturb that
propagates" and wave as pattern-figure-graphics-representation of
interference pattern of voltage/current measured along the TL). This
"wave pattern" (is it correct to write "wavy" pattern?) do not carry
any energy from one place to another on the TL it is not a "wave" in
the other sense (transport phenomena). What do you think?

(1) Terman F.E. "Radio engineering". McGraw Hill.1947 Ed. page 78

73

Miguel Ghezzi - LU6ETJ

On Jun 3, 12:51*am, Cecil Moore wrote:
On Jun 2, 11:48*am, K1TTT wrote:

my differential calculus is a bit rusty, but i don't think that
equation satisfies the basic wave equation.

My calculus is probably a lot rustier than yours but it would be very
important for this discussion if Maxwell's equations do not work for
the standing wave equation. That would essentially prove that the
mashed-potatoes theory of transmission line energy is bogus.
--
73, Cecil, w5dxp.com

well, i dug out mathcad that will do the ugly symbolic differentiation
for me. the standing wave equation can not satisfy the wave equation
derived from maxwell's equations as shown in either 'Fields and Waves
in Communications Electronics' section 1.14 or 'Classical
Electrodynamics' section 6.4. Both of them come down to the
requirement that the second derivative wrt space be proportional to
the second derivative wrt time. The proportionality constant is the
velocity squared. In order to satisfy this the equation must be a
function of the form F(t-x/v), the normal representation is the
complex exponential which can be presented in a form like sin(t)cos(x/
v)-cos(t)sin(x/v) the simpler standing wave equation sin(kx)sin(wt)
has the wrong relationship between space and time and therefor can't
be a solution to the wave equation. When i work through the second
derivatives and collect terms it results in something like
Asin(kx)sin(wt)(k^2-w^2) which makes no sense, even in a dimensional
analysis the units don't work.

The easiest explanation though is still the intuitive one, the
solution of the wave equation derived from maxwell's equations results
in the proportionality constant of 1/c^2 which requires the speed of
the wave to be c in the medium where it is evaluated, there is no way
to get that from the standing wave equation since it is obviously
stationary wrt space.

On Jun 4, 6:35*am, K1TTT wrote:
The easiest explanation though is still the intuitive one, the
solution of the wave equation derived from maxwell's equations results
in the proportionality constant of 1/c^2 which requires the speed of
the wave to be c in the medium where it is evaluated, there is no way
to get that from the standing wave equation since it is obviously
stationary wrt space.

Thanks David, that's good news. It apparently means that the arguments
based on energy not crossing a current node boundary in a standing
wave are invalid - since that singular condition violates the boundary
conditions for Maxwell's equations. So does the "standing wave energy
standing still" argument. Not only does the photonic nature of EM
waves require them to travel at the speed of light in the medium, but
so does Maxwell's equations.

Such knowledge also has ramifications for the technique of using the
current on a standing wave antenna to try to predict the delay through
a loading coil. If a Maxwell equation analysis of such a condition
yields bogus results, how can simple current phase measurements be
trusted? If the component traveling waves associated with a loading
coil were used in order to obtain a valid Maxwell equation analysis, I
wonder what would be the predicted delay through the coil?
--
73, Cecil, w5dxp.com

On Jun 4, 2:12*pm, Cecil Moore wrote:
On Jun 4, 6:35*am, K1TTT wrote:

The easiest explanation though is still the intuitive one, the
solution of the wave equation derived from maxwell's equations results
in the proportionality constant of 1/c^2 which requires the speed of
the wave to be c in the medium where it is evaluated, there is no way
to get that from the standing wave equation since it is obviously
stationary wrt space.

Thanks David, that's good news. It apparently means that the arguments
based on energy not crossing a current node boundary in a standing
wave are invalid - since that singular condition violates the boundary
conditions for Maxwell's equations. So does the "standing wave energy
standing still" argument. Not only does the photonic nature of EM
waves require them to travel at the speed of light in the medium, but
so does Maxwell's equations.

definately. another simple condition shows this can't be correct
since current nodes correspond with voltage peaks in the standing wave
pattern, so while energy in the magnetic field is a minimum the energy
in the electric field is a maximum.


Such knowledge also has ramifications for the technique of using the
current on a standing wave antenna to try to predict the delay through
a loading coil. If a Maxwell equation analysis of such a condition
yields bogus results, how can simple current phase measurements be
trusted? If the component traveling waves associated with a loading
coil were used in order to obtain a valid Maxwell equation analysis, I
wonder what would be the predicted delay through the coil?
--
73, Cecil, w5dxp.com

this becomes MUCH harder to analyze. the transmission line case is
easy because the equations collapse to a single linear dimension, so
you can write your simple standing wave equation with a single sin(kx)
term. in a solenoid, especially a finite length solenoid, and double
especially because the length may be an appreciable fraction of a
wavelength, there is no such simple representation for the fields.
i'm not even sure what software would provide an adequate model of
something like that... the turns are too close for me to trust nec
based programs with out lots more research, and i'm pretty sure finite
element programs like ansoft/maxwell would not be able to handle the
change in current due to length and radiation. measurement of the
currents in coils like that would also be hard because of the radiated
fields and the shielding needed to prevent measurement errors from
probe lengths in the field... i would only trust fiber optic sensed
probes that were small and self contained, at least that way you would
not be distorting the field with probes or trying to cancel out pickup
from probe cables coupling to the antenna.

On 4 jun, 14:26, K1TTT wrote:
On Jun 4, 2:12*pm, Cecil Moore wrote:





On Jun 4, 6:35*am, K1TTT wrote:

The easiest explanation though is still the intuitive one, the
solution of the wave equation derived from maxwell's equations results
in the proportionality constant of 1/c^2 which requires the speed of
the wave to be c in the medium where it is evaluated, there is no way
to get that from the standing wave equation since it is obviously
stationary wrt space.

Thanks David, that's good news. It apparently means that the arguments
based on energy not crossing a current node boundary in a standing
wave are invalid - since that singular condition violates the boundary
conditions for Maxwell's equations. So does the "standing wave energy
standing still" argument. Not only does the photonic nature of EM
waves require them to travel at the speed of light in the medium, but
so does Maxwell's equations.

definately. *another simple condition shows this can't be correct
since current nodes correspond with voltage peaks in the standing wave
pattern, so while energy in the magnetic field is a minimum the energy
in the electric field is a maximum.



Such knowledge also has ramifications for the technique of using the
current on a standing wave antenna to try to predict the delay through
a loading coil. If a Maxwell equation analysis of such a condition
yields bogus results, how can simple current phase measurements be
trusted? If the component traveling waves associated with a loading
coil were used in order to obtain a valid Maxwell equation analysis, I
wonder what would be the predicted delay through the coil?
--
73, Cecil, w5dxp.com

this becomes MUCH harder to analyze. *the transmission line case is
easy because the equations collapse to a single linear dimension, so
you can write your simple standing wave equation with a single sin(kx)
term. *in a solenoid, especially a finite length solenoid, and double
especially because the length may be an appreciable fraction of a
wavelength, there is no such simple representation for the fields.
i'm not even sure what software would provide an adequate model of
something like that... the turns are too close for me to trust nec
based programs with out lots more research, and i'm pretty sure finite
element programs like ansoft/maxwell would not be able to handle the
change in current due to length and radiation. *measurement of the
currents in coils like that would also be hard because of the radiated
fields and the shielding needed to prevent measurement errors from
probe lengths in the field... i would only trust fiber optic sensed
probes that were small and self contained, at least that way you would
not be distorting the field with probes or trying to cancel out pickup
from probe cables coupling to the antenna.- Ocultar texto de la cita -

- Mostrar texto de la cita -

Hello and good day all:

I believe perhaps I am not translating/understanding well your posts,
Cecil and David, I post some comments to your consideration.

As I learnt, basic electromagnetic energy propagation Maxwell
equations are satisfied by a traveling wave moving in one direction.
Also I learnt standing waves in a TL results of two of them traveling
in opposite directions (as I understand this is not a questioned point
in this newsgroup), but SW equation it is not a Maxwell eq. solution
but a mathematical result of interference among them. For that reason
directly replacing this one in electroamagnetic energy propagation
Maxwell diff. eqs to satisfy it, do not work, because SW do not travel
anywhere!.
Energy not flowing beyond nodes it is a true, but only for ending
nodes!
Could this be what confuses those who think energy do not cross
INTERNAL TL nodes?

Electromagnetic waves are energy transport phenomenom, SWs not. We can
interpret last ones as a "result of the transport
phenomenom" (interference) = Energy is "trapped" in a resonant ideal
line, as is "trapped" in a resonant ideal cavity, as light ii is
"trapped" in a optical ideal cavity.

Do we see a simple case: If we think in a half wave resonant line we
can interpret/describe its internal state as two traveling waves
(inside system transport) or with a standing wave dynamic interchange
of energy between E and H field without radiation (not transport). In
longer line it is the same: we can describe its internal state a two
waves traveling between end boundaries (transport) or a sistem (line)
located [but not f(x)] energy interchange among magnetic and electric
field. (I said not f(x), because nodes and antinodes are "FIELDS (E
and H) nodes and antinodes", but not "ENERGY nodes or antinodes" (as
we know, where H is 0, E is maximun...)
Seems to me this does not violate any quantum or clasic laws :)

73

Miguel Ghezzi - LU6ETJ

On Jun 4, 12:26*pm, K1TTT wrote:
this becomes MUCH harder to analyze. the transmission line case is
easy because the equations collapse to a single linear dimension, so
you can write your simple standing wave equation with a single sin(kx)
term. in a solenoid, especially a finite length solenoid, and double
especially because the length may be an appreciable fraction of a
wavelength, there is no such simple representation for the fields.

Well maybe it is much harder using Maxwell's equations but maybe there
is a simple representation. See what you think about this idea. At the
following web site is an impedance calculator that will yield the
characteristic impedance and velocity factor of a loading coil so the
coil can be analyzed the same way as a transmission line. (We also can
model the whip using EZNEC and, like a transmission line stub, equate
the feedpoint impedance to the impedance of a lossy open-circuit
stub.) We know the Z0 of the whip will be a few hundred ohms.

http://hamwaves.com/antennas/inductance.html

The velocity factor of the specified coil can be calculated from the
axial propagation factor in radians per meter.

So please assume a frequency of 4 MHz and a typical six inch long
bugcatcher loading coil with a Z0 of 3800 ohms and a VF of 0.024. All
losses in/from the coil can be lumped together as if they were normal
transmission line losses. The electrical length of the coil can be
calculated from the physical length and VF. I don't see that it is all
that "MUCH harder to analyze" than a transmission line example with
the same amount of losses.
--
73, Cecil, w5dxp.com

On Jun 4, 1:26*pm, K1TTT wrote:
On Jun 4, 2:12*pm, Cecil Moore wrote:
Thanks David, that's good news. It apparently means that the arguments
based on energy not crossing a current node boundary in a standing
wave are invalid - since that singular condition violates the boundary
conditions for Maxwell's equations. So does the "standing wave energy
standing still" argument. Not only does the photonic nature of EM
waves require them to travel at the speed of light in the medium, but
so does Maxwell's equations.

definately. *another simple condition shows this can't be correct
since current nodes correspond with voltage peaks in the standing wave
pattern, so while energy in the magnetic field is a minimum the energy
in the electric field is a maximum.

And yet....

It is generally accepted that power = volts times current (P=VI) and
that
power is energy flowing, so if the voltage or current is always 0,
there
must be no energy flowing.

The presence of voltage without current, or current without voltage is
an indication that energy is stored, not that energy is flowing.

So are you really prepared to give up on P=VI so that energy can be
flowing (i.e. there is power) when the voltage or current is zero?

....Keith

On Jun 3, 4:03*pm, lu6etj wrote:
Thanks to all

Hey boys! (Cecil, David, Michael, et al) It is very funny and
entertaining, I enjoy your postingss mostly in "read only" mode
because translate not simple mine ones still being a struggle for
me :-)
....
Cecil, I never studied standing waves with Maxwell equations (except
in usual examples of cavity resonators cases learning classes), I
studied only classic electric differential solution to the
telegraper's equations.

Hi Keith: *We tend to think of energy as a "tangible and real" easely
intuited thing "out there" (as a water or horses) but we must not
forget energy is a really elusive CONCEPT devised to explain changes
in physical systems. Familiarity tend us to fetishize concepts, then
we easily can get caught in troubles type = "Where velocity goes when
the car smash?" :-D :-D. We must be carefully with forces, powers,
velocities, etc. in this sense...
Note how Terman prudenty deals with differential solution of
Telegrapher's equations: "This combinatiosn of voltage and current can
be INTERPRETED as a wave train traveling toward receiver" (1)
(capitalized letters by me).

Terman does seem to be extraordinarily careful with his language.

The very term "standing waves" leads to endless Ham controversies
about concept of "wave" word in our context.(wave as "a disturb that
propagates" and wave as pattern-figure-graphics-representation of
interference pattern of voltage/current measured along the TL). This
"wave pattern" (is it correct to write "wavy" pattern?) do not carry
any energy from one place to another on the TL it is not a "wave" in
the other sense (transport phenomena). What do you think?

I tend to agree. Wave is an overloaded term and this leads to some of
the confusion. There are some phenomena that transport energy which
have a wavy nature. This does not mean that every thing with a wavy
nature is transporting energy.

In particular, it does not mean that when there is a situation in
which
energy is not being transported (e.g. a zero on a transmission line),
that just because the conditions on the line can be described by
decomposing into two waves going in opposite directions, that these
two waves are carrying energy.

Attempting to do this, and believing that these decomposed waves
actually
represent energy flows leads to having to answer questions like "where
does the reflected energy go"? When I first started lurking in this
group
about a decade and half ago, the 'obvious' answer accepted by many was
that it went in to the final and fried the tube. Many have moved
beyond
this simplicity, but some have not yet moved as far as they need to.

....Keith