On 29 Nov, 09:11, Jim Kelley wrote:
Cecil Moore wrote:
W8JI's mistake was using standing wave current to try
to measure that delay.

It's not at all apparent that that was his mistake.

Even though the delay changes with frequency,
it is highly unlikely to drop from 90 degrees to 4.5
degrees in a few MHz.

Any phase delay given in degrees would of course vary as function of
angular frequency independent of any systematic effect simply by
virtue of the fact that the amount of time per period varies with
frequency while the number of degrees per period obviously do not.

Over the range of a few octaves, propagation delay on the other hand
does not vary to any significant extent as a function of frequency.
Ostensibly, it should be equal to sqrt(LC) series L, shunt C.
e.g.

http://www.rhombus-ind.com/dlcat/app1_pas.pdf

In order to either validate or invalidate claims, one must do at least
two things. First make verifyable and repeatable measurements.
Second, show how those measurements are supported by the underlying
principles, and are predicted by the associated mathematics. Without
those things, you may as well go shout it at cars.

Actually, it is an exercise in the physics of reality.
A 3nS delay through a 100 uH coil is the real "exercise
in philosophical fantasy" and obviously impossible.

The display on Tom's web page appears to be set for 100ns per
division. The delay between cursor 1 and cursor 2 is 486.43 nS, and
the position of cursor 1 appears to be arbitrarily set. The 3nS
measurement would be at ~0.3% of full scale - not normally the scale
one would employ to make such a measurement. Lacking any sort of
description of the stimulus or of the instrument, it's not clear to me
what W8JI's test unit is actually measuring. But at least he measured
something and isn't shouting at cars about it.

73, ac6xg

Darn it! why haven't you spoken up before with respect to slow wave
properties and the parameters required to make them? You could have
helped a lot in my threads on Gaussian antennas by cutting off old
wive tales.
Art KB9MZ