Yuri Blanarovich wrote:
Soooo, W8JI and his worshippers were right! Current is just about constant
through the loading coil (for traveling wave) ...

Especially since I modeled the coil with lossless wire. :-)

*Traveling wave current* amplitude is just about constant
at both ends of a loading coil but there's a phase shift
as can be seen at: http://www.w5dxp.com/current2.htm
In the middle of the coil, the current increases because
of the adjacent coil coupling. There is a little drop off
(unit percents)in amplitude end-to-end because of I^2*R
losses and radiation. But one can consider the coil to be
lossless and non-radiating and still get within a few percent
of reality.

The problem is that W8JI used *standing wave current* for
his measurements. What is flowing through the coil is the
forward current and reflected current, not the standing
wave current. The standing wave current is just standing
there as indicated by the cos(kz) term. The amplitude of the
standing wave current at any point in the coil or on the
antenna has more to do with the phase difference between
the forward and reflected currents than anything else. At
the tip of the antenna, the forward current and reflected
current are equal in magnitude, 180 degrees out of phase,
and thus sum to zero.

I hope Roy approves your use of EZNEC for this demonstration and perhaps
will admit that they were wrong, and indeed the RF current through standing
wave antenna circuit, such a quarter wave resonant vertical monopole, the
loading coil has the current drop along the coil (standing wave circuit).

The current "drop" is an illusion. The current decreases primarily
because of out-of-phase addition of the forward and reflected
current. If one makes the antenna longer and places the loading
coil somewhere else, one can measure a current "rise" through the
coil which is still an illusion created by the in-phase addition
of the forward and reflected currents.

I verified these findings on the bench a couple of months ago
using my 75m Texas Bugcatcher coil loaded with a 3K ohm resistor.
But I wanted to see if EZNEC agrees. It does.
--
73, Cecil http://www.w5dxp.com

On May 6, 9:05 am, Cecil Moore wrote:

In the middle of the coil, the current increases because
of the adjacent coil coupling.

I'd like to see your Norton analysis of that one.

73, ac6xg

Jim Kelley wrote:
I'd like to see your Norton analysis of that one.

RF is not DC. Edison questioned how one could measure
100 volts between any two of three terminals. :-)
--
73, Cecil http://www.w5dxp.com

Cecil Moore wrote:
Jim Kelley wrote:

I'd like to see your Norton analysis of that one.


RF is not DC. Edison questioned how one could measure
100 volts between any two of three terminals. :-)

Are you implying yours is a 3-phase antenna? :-)

ac6xg

Jim Kelley wrote:
Are you implying yours is a 3-phase antenna? :-)

No, just that phasing of RF signals is what is confusing
the DC gurus, just like AC phasing confused Edison.
--
73, Cecil http://www.w5dxp.com

Cecil Moore wrote:

Jim Kelley wrote:

Are you implying yours is a 3-phase antenna? :-)


No, just that phasing of RF signals is what is confusing
the DC gurus, just like AC phasing confused Edison.

What is a DC guru, and why do you address comments to them?

As a suggestion, you might consider increasing the current for the
EZNEC simulation on your webpage. At 20 amps per division it's plus
or minus a pixel at 1024x768.

73, ac6xg

Jim Kelley wrote:
As a suggestion, you might consider increasing the current for the EZNEC
simulation on your webpage. At 20 amps per division it's plus or minus
a pixel at 1024x768.

Excellent suggestion, Jim. I'm sure there is a way to do that
within the EXCEL charting function but, so far, I haven't figured
out how to split the scales. I was going to mow the yard but it's
92 degrees out there and I would rather play with EZNEC anyway.
--
73, Cecil http://www.w5dxp.com

Jim Kelley wrote:
As a suggestion, you might consider increasing the current for the EZNEC
simulation on your webpage.

Done as you suggested by changing the current amplitude scale.
What do you think about the simulation? Stand by for more
additions to that web page.
--
73, Cecil http://www.w5dxp.com

Cecil, W5DXP wrote:
"No, just that phasing of RF signals is what is confusing the DC gurus,
just like AC phasing confused Edison."

In W8JI`s pages I found this on the subject of "Mobile antennas, short
verticals, loading" :
It`s long and Tom warns about taking anything from context, so it should
be searched out and read in its entirety. I have no quarrel with most of
Tom`s pages but find this statement curious:
"When current flows in the transmitter-end of the coil, a magnetic field
is created. The time-varying magnetic field causes charges in the other
turns to instantly move."

Instant movement of charges is instant current, and everyone knows that
current in a coil lags the voltage.

Best regards, Richard Harrison, KB5WZI

Richard Harrison wrote:
"When current flows in the transmitter-end of the coil, a magnetic field
is created. The time-varying magnetic field causes charges in the other
turns to instantly move."

Instant movement of charges is instant current, and everyone knows that
current in a coil lags the voltage.

Instant movement of charges is impossible except in the mind
of someone using the lumped-element model. Apparently, anything
is possible in that kind of mind. As Dr. Corum said: "Lumped
circuit theory fails because it's a *theory* whose presuppositions
are inadequate. Every EE in the world was warned of this in their
first sophomore circuits course. ... Lumped circuit theory isn't
absolute truth, it's only an analytical *theory* - and in those
resonators we have the case where this sophomore *theory* fails
*experimentally. The engineer must either use Maxwell's equations
or distributed elements to model reality."
--
73, Cecil http://www.w5dxp.com