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.