Cecil,

One more time.

In a standing wave antenna problem, such as the one you describe, there
is no remaining phase information. Any specific phase characteristics of
the traveling waves died out when the startup transients died out.

Phase is gone. Kaput. Vanished. Cannot be recovered. Never to be seen
again.

The only "phase" remaining is the cos (kz) term, which is really an
amplitude description, not a phase. The so-called "phase reversal" in
longer antennas is not really about phase either. It is merely a
representation of the periodic sign reversal seen in a cosine function.
(This is one more definition of phase to add to the confusion.)

Of course, all of this depends on an ideal system with no losses, etc.
The real world is not ideal, but your posed problem does not appear to
contain any of those nasty realities. You have undoubtedly seen small
phase offsets reported in EZNEC for this sort of antenna. Those phase
offsets represent the impact of real-world effects, such as radiation
and ground effects.

The applicability of linear superposition and the assumption of
steady-state conditions means that the resulting standing wave contains
ALL of the possible information about the system in steady-state mode.
Yes, you can divide the problem back into two traveling waves, in the
manner that Kraus, Balanis, and the entire world understand. But you
won't gain any new information by doing so, because any unique traveling
wave information is permanently lost.


73,
Gene
W4SZ



Cecil Moore wrote:

[snip]

These are not the results predicted by my neighboring ham friend.
I'm confused but here are the things I know for sure.

1. The resonant frequency changed when I installed the coil so
the coil is not a perfect replacement for the wire.

2. The feedpoint impedance decreased from 60 ohms to 45
ohms. Since 45 ohms is closer to 50 ohms than is 60 ohms,
I'm not too interested in knowing why..

3. The current at 'x' increased from 0.92 amp at 0 deg in the
wire dipole to 1.1 amp at 0 deg in the loaded dipole. The phase
didn't change.

4.The current at 'y' increased from 0.38 amps at 0 deg in the
wire dipole to 0.6 amp at 0 deg in the loaded dipole. The phase
didn't change.

5. No matter where I measure the current in either system, the
phase always comes up zero degrees between any two points
from tip to tip anywhere on either dipole no matter how far
apart are the measurement points. My neighboring ham friend said the number
of degrees in the coil had to be the number of degrees in the
wire and indeed, both are measured to be zero degrees, but
I wonder if that's really what he had in mind when he said
the delay would be equal. Zero equals zero, but what does
that mean for me?

The change in feedpoint impedance and the different current
magnitudes don't much bother me but I am really bothered
by those phase measurements. The dipole is 180 degrees long
and the current should be changing phase, at least on the wire
if not through the coil. I need some expert to explain how those
phase measurements on the wire are possible on both antennas.
I know my phase measurements are correct but why are they
always zero degrees? And since they are always zero degrees,
what information are they providing?
--
73, Cecil, W5DXP