Jim Kelley wrote:
Cecil Moore wrote:
Kraus, in his book entitled "Antennas" ignores almost nothing about
antennas.

On the contrary, when Kraus talks about standing-wave
antenna current, he ignores everything except standing
waves. Here are some quotes:

"Antennas ...", by Kraus, 3rd edition:
Standing Wave Antennas

Page 187: "A sinusoidal current distribution may be
regarded as the standing wave produced by two uniform
(unattenuated) traveling waves of equal amplitude moving
in opposite directions along the antenna."

Page 464: "It is generally assumed that the current
distribution of a thin-wire antenna is sinusoidal, and
that the phase is constant over a 1/2WL interval, ..."

Both of those statements assume nothing but standing wave
current on a standing wave antenna. Have you looked at
that graph of standing wave current amplitude and phase
that Kraus provides in "Antennas"?

Kraus normalizes the feedpoint current to 1.0 and that's
good enough for me.

Yes, unless of course you're talking about a real antenna with actual
current on it. That is what I thought we were talking about. My
recollection is that it was resonant on 75 meters, and the coil and
stinger have very specific dimensions.

Unfortunately, the simulation of a 75m Bugcatcher loading
coil violates the EZNEC segmentation rules on 4 MHz. To
avoid objections to such, I have used the 75m Bugcatcher
loading coil form factor on a loaded 40m mobile antenna
using about 14 turns. EZNEC doesn't complain about that
6" diameter, 4 tpi form factor used on 40m. That 40m
mobile antenna file can be downloaded from:

http://www.w5dxp.com/coil426.EZ

The current at the bottom of the coil is
1.0168 amps at 0.00 degrees

The current at the top of the coil is
..8179 amps at -0.06 degrees

In this case, the delay through the coil is unrelated
to the phase shift.

The actual value of Imax obviously depends
upon the power incident upon the antenna. If one assumes a
current of 1.0 at the feedpoint of the coil, then one can calculate
the Imax at the base of the stinger given the Z0 of the loading
coil and the Z0 of the stinger.

It might even be better to measure it - with some type of current probe
device. Then you could solve for phase at any x or t you want.

Roy already made the necessary measurements. All he needs
is help in comprehending the results. Unfortunately, he is
still suffering from the misconception that the current
phase that he "measured" is associated with the propagation
delay through the loading when it is not.

The phase of the current in a standing wave antenna
changes hardly at all through a wire or through a loading
coil. Running the above file under EZNEC proves that
statement. Roy has even, in the past, agreed with the
EZNEC results yet he continues to ignore the nature of
the current on a standing wave antenna as reported by
EZNEC. Go figure.

As Gene Fuller asserted years ago, the phase information
in the current on a standing-wave antenna is buried in
the current magnitude measurement, not in the current
phase measurement. You seem to agree.

But Roy did NOT use the magnitude measurement to calculate
the phase shift!!! I explained how to take the ARCCOSine
of the current normalized magnitude to calculate the actual
phase shift through a wire more than 5 years ago. He called
the concept gobbledygook, plonked me, threatened to refund
my EZNEC purchase price, and revoke my customer support.

An EZNEC simulation using the *SAME* 40m loading coil above
using traveling wave current, showing an actual phase shift
of ~40 degrees is at:

http://www.w5dxp.com/coil426s.EZ

The current at the bottom of the coil is
1.0053 amps at -3.25 degrees.

The current at the top of the the coil is
..90356 amps at -43.43 degrees.

In this case, the delay through the coil is proportional
to the phase shift.

Hopefully, you or someone else who understands what I am
saying will contact Roy about his conceptual blunders.
He keeps trying to avoid the discussion of large bugcatcher
loading coils by retreating to the shelter of a small
toroidal coil which more closely matches the lumped-circuit
model along with his mistaken concepts. Unfortunately, his
small toroidal coil bears no resemblance to a 75m Texas
Bugcatcher coil which is the subject of the discussion.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com