On Apr 23, 1:34*pm, "Tom Donaly" wrote:
steveeh131047 wrote:
On Apr 23, 4:42 pm, Jim Kelley wrote:
For a more quantitative illustration of how distributed reactance in
transmission lines causes delay seehttp://www.rhombus-ind.com/dlcat/app1_pas.pdf

73, ac6xg

Jim, thanks for the reference.

Perhaps I should have expressed myself more clearly. What I've not
seen, for example, is a lumped-element analysis which takes just the
coil dimensions as input, and predicts theoretically - without a lot
of empirical "tweaking" - the reactance at a particular frequency;
particularly a frequency close to self-resonance. There may be one out
there, but I've not yet found it!

In contrast, the ON4AA calculator - based on Corums' transmission-line
analysis - does just that, and produces results which seem to match
well the EZNEC modelling results.

Regards,
Steve G3TXQ

EZNEC is a mathematical model just as the transmission line model is
a model. EZNEC doesn't use a transmission line
analog in order to reach its conclusions. If you're really interested
in this subject, you have to read Schelkunoff and others who did the
research on this years ago. A big, honking loading coil doesn't
act much like a lumped component. It makes a pretty shabby transmission
line, too. If you want to understand it, you have to study
electromagnetics and approach it from that standpoint, which may not
be easy. Finally, a modest question: if you have EZNEC, why would you
be wasting time with something inferior? The gold standard is the gold
standard. Or are you on some philosophical quest, like Cecil?
73,
Tom Donaly, KA6RUH

Tom,TomTom.
Eznec DOES use the transmission line analogy because like Gauss it
uses an abitrary border where the contents are in equilibriumn or in a
state of balance where all forces are accounted for when a time
varying field is applied. The same goes for a transmission line where
the radiation factor is also accounted for.
The radiation force losses are accounted for by the depreciating
impedance with time
which is also shown by the deprecating amplitude of occilation where
each period loss of amplitude represents radiation energy. If the
amplitude showed no change then you have a tank circuit without
friction or other losses. No losses means perpetual motion and vica
versa. If on Earth friction is always there which is also equal to the
energy for an acceleration of a particle. On the reverse side, a
deccelerating force on a particle represents kinetic energy as opposed
to the potential energy supplied for radiation where the product is
seen as light. As with a light bulb radiant heat is what we know as
light. Just classical physics no less
Art