"Roy Lewallen" bravely wrote to "All" (07 Apr 05 15:08:40)
--- on the heady topic of " VF, low-loss line, high-impedence line -
relationship"

RL From: Roy Lewallen
RL Xref: aeinews rec.radio.amateur.antenna:28088

RL Asimov wrote:

Since a portion of the EM field in open wire line is free to travel
outside the conductor into the environment then we may safely assume
there is an exchange between the environment and the conductor.

RL If the conductors are perfectly conducting, no part of the field at
RL all exists within the conductor. With good conductors like copper and
RL at HF and above, there's very little penetration of the conductor by
RL the fields, either electric or magnetic.

Is there any electron current in the conductor or not?


RL First of all, a mismatch doesn't cause loss.

An impedance mismatch in any medium causes a scattering of the energy.
Of course, it isn't a net loss as far as the universe is concerned but
some of the energy doesn't arrive where it was intended.


RL Secondly, as I explained in my last posting, the characteristic
RL impedance of a transmission line isn't the same thing as the
RL characteristic impedance of free space.

May I suggest you make up your mind whether the electric energy is
travelling in a conductive medium or not?



RL It has to do with the reflective
coefficient where the energy is returned.

RL Well, no. There isn't a bundle of energy trying to escape the line and
RL bouncing off the air, or bouncing off the air as it travels along the
RL line, or bouncing off the conductors into the air. So reflection
RL coefficient isn't applicable here.

What makes you so sure?


RL I'm afraid that the conclusions you've reached about loss and
RL characteristic impedance are based on a poor understanding of
RL fundamental transmission line operation. The result is some
RL conclusions that are, and are well known to be, untrue.

I think you are only concerned with modeling of transmission lines as
lumped constants but models can only go so far in explaining how
something works. Models are like analogies and we all know no analogy
is perfect even this one.

A*s*i*m*o*v

.... Anyone not wearing 2,000,000 sunblock is gonna have a REAL_ BAD_ DAY_7