Cecil,

I am fully aware of the "original argument". To confess my bias, I agree
with Tom D. and Tom R. There is no "current drop" ever, and there is no
current change in an ideal inductor. W8JI explains in some detail why
real coils show different currents at each end.

My response was aimed at your little demo circuit. Let me share one of
my own.


----------------------------------------------------
+ | | |
------------ ----------- -----------
| | | Ra | | Rb |
| 1 V DC | | 100 Ohm | | 100 Ohm |
| 20 mA | | 10 mA | | 10 mA |
------------ ----------- -----------
- | | |
----------------------------------------------------


The source provides 20 mA, but Rb passes only 10 mA. Would you call this
a "current drop"? Most people would say that the total current has
simply divided into multiple paths.

Your RG-58 transmission line example is no different. The current from
the source is not lost or "dropped". It simply finds other paths in
addition to the "load" to return back to the source. Antennas and
loading coils exhibit the same phenomenon.

The error is in considering the transmission line as simply two
non-interacting conductors that somehow magically enforce a fixed
impedance, Zo. If the conductors did not interact there would be no
fixed impedance; it would not be a transmission line.

Your reference to simple DC analysis ignores the interaction between the
transmission line conductors. If you modeled the problem correctly you
would need to account for the leakage current. There would be no
"current drop" and no mystery.

The laws of electromagnetics do not change in any fundamental way until
relativistic and/or quantum considerations come into the picture. There
are "different horses for different courses", and there are different
"computationally preferred" approaches to different electromagnetic
configurations. Often there is best choice for practical reasons, but
that does not make the more difficult computation wrong.

73,
Gene
W4SZ


Cecil Moore wrote:
Gene Fuller wrote:

No one has ever discussed simple series DC concepts except you.


Don't you recognize "17th century DC concepts" as sarcasm?

What is wrong is calling a lossy transmission line a "simple series
circuit" and then misapplying the theory.


That's exactly my point, Gene. I think you missed it. What is
wrong is assuming a simple one-way series current flowing through
a point inductance in a *standing-wave* mobile antenna containing
a one foot by one foot 75m *bugcatcher* coil that occupies more
than 60 degrees of an electrical 1/4 wavelength.

The original argument originated over on eHam.net. Tom, W8JI
said there is no change in current from end to end in a loading
coil. Yuri disagreed. Everything else is a fallout from that
original argument.