RadioBanter - View Single Post

March 15th 06, 06:55 PM posted to rec.radio.amateur.antenna

wrote:
That just shows how poorly we sometimes understand the workings of an
inductor.

There you go again, implying through inuendo that that 'we'
includes me but not you. This discussion is not about you
and me so I will make a few generalized statements.

An individual can understand perfectly how an inductor
works within the presuppositions of the lumped-circuit
model yet be completely ignorant of how an inductor
actually works in the real world in a distributed-network
environment.

The presuppositions of the lumped-circuit model cannot
be used to prove the validity of the lumped-circuit
model. The presuppositions of the lumped-circuit model
are invalid for many distributed-network environments.

This is a technical subject so I will ask a technical
question:

How is it possible to use a signal (standing wave current)
that is known not to change phase, to measure the phase delay
through a wire or coil?

Kraus provides a graph of that unchanging phase in Figure
14-2 of "Antennas for All Applications", 3rd edition.

The fact an inductor has self-resonance at one frequency (16MHz) does
not mean we can assume it is 90 degrees at that frequency and 45
degrees at half of that frequency!!

It certainly means we can make those assumptions within some
estimated degree of accuracy because they agree with the laws
of physics which don't change just because some individual
rejects them. Helicals, in general, obey the transmission line
laws of physics. They have relatively constant values of L, C,
R, and G over a certain range of frequencies. They exhibit the
characteristics of Z0 and VF. They do NOT exhibit the
presuppositions of the lumped-circuit model.

This business of treating an inductor like a transmission line is
destined to produce theories that crash and burn.

Inductors have been treated like transmission lines for the
better part of a century by engineers using the distributed
network model. Since the distributed network model is a
superset of the lumped-circuit model, why would they ever
crash and burn?
--
73, Cecil http://www.qsl.net/w5dxp