Jim,

I have conceded. I simply do not know how to deal with someone who uses
models to prove that models are misleading. Cecil's "reality", wherever
that comes from, trumps all.

I have not measured transmission lines in the vacuum of free space, so I
must rely on models. Since Cecil claims some sort of devine connection
to model-less reality he clearly must be correct. (Probably explains his
intimate knowledge of reality in the vacuum of free space.)

73,
Gene
W4SZ


Jim Kelley wrote:



Gene Fuller wrote:

Cecil,

Nice try.

Here's the reference: From "Fields and Waves" by Ramo and Whinnery.
Take a close look at the exponential transmission line equations
for flat lines (no reflections):

V = Vmax(e^-az)(e^wt-bz) (1)

I = Vmax(e^-az)(e^wt-bz)/Z0 (2)

'a' (alpha) is the attenuation factor. The two equations are identical
except for the Z0 term. If you divide equation (1) by equation (2),
you get Z0. In a flat transmission line (no reflections) the current
is ALWAYS equal to the voltage divided by the characteristic impedance
of the transmission line. The voltage and current are attenuated by
EXACTLY the same factor. If the voltage drops because of I^2*R losses,
the current must decrease by exactly the same percentage. (I have
avoided
calling it a current drop so it wouldn't upset you.)

Since the attenuation factor is R/2*Z0 + G*Z0/2 and since, for most
transmission lines used on HF, R/2*Z0 G*Z0/2, the current attenuation
is caused by the series I^2*R drop in the voltage and the V/I=Z0 ratio
that must be maintained - pretty simple logic.


So Gene, you should have asked the question: if one has a circuit with a
thousand resistors all connected in series and no current paths in
shunt, how does one arrive at a different current through R1000 than
through R1?

73, Jim AC6XG

Gene Fuller wrote:
Since Cecil claims some sort of devine connection
to model-less reality he clearly must be correct.

On the contrary - I don't believe in divinities at all.
That's exactly why I don't worship math models (like some
people I know) as if they possessed supernatural powers.

It is ridiculous to try to force a distributed network
problem to obey the rules of circuit analysis. The
distributed network analysis model was developed
specifically because distributed networks do NOT obey
the boundary conditions necessary for the circuit analysis
model to yield valid results.

When the only tool you have is a hammer, everything
looks like a nail. Math models are tools. Please
choose a valid one for whatever problem you are
trying to solve.
--
73, Cecil http://www.qsl.net/w5dxp