Tom Donaly wrote:
Jim Lux wrote:
Tom Donaly wrote:
Finally, a modest question: if you have EZNEC, why would you
be wasting time with something inferior? The gold standard is the gold
standard.
Perhaps more the silver or electrum standard.
EZNEC doesn't do dielectric loading, for instance. (unless you get the
Nec4 engine from Roy)
And, it's a MoM code, so things not well represented by collections of
wires aren't necessarily modeled well.

Nothing is perfect, but which is better, EZNEC or the Cecil-Corum method
of modeling antennas?

Depends on what your modeling needs are. NEC and it's ilk are more
generalized, but take more computational effort. The Corums have an
analytical approximation that is reasonably good for a certain class of
configurations, although I have to say that for the original Corum
application of Tesla Coils, a lumped approximation gets you almost as
close, at much less work, considering the usual construction tolerances
in a tesla coil. Modern Tesla Coil modeling is typically done with
either a lumped model or a FEM code that assumes it's axially symmetric
and often an assumed voltage distribution. The assumed distribution the
result of a combination of more detailed analytical modeling and some
experimental measurements on real coils, and speeds up the computation
drastically, while not adversely affecting the accuracy of the results
(that is, the changes are less than a few percent, comparable to
construction tolerances on these things).



73,
Tom Donaly, KA6RUH

On Apr 23, 7:49*pm, Jim Lux wrote:
Tom Donaly wrote:
Jim Lux wrote:
Tom Donaly wrote:
Finally, a modest question: if you have EZNEC, why would you
be wasting time with something inferior? The gold standard is the gold
standard.
Perhaps more the silver or electrum standard.
EZNEC doesn't do dielectric loading, for instance. (unless you get the
Nec4 engine from Roy)
And, it's a MoM code, so things not well represented by collections of
wires aren't necessarily modeled well.

Nothing is perfect, but which is better, EZNEC or the Cecil-Corum method
of modeling antennas?

Depends on what your modeling needs are. *NEC and it's ilk are more
generalized, but take more computational effort. *The Corums have an
analytical approximation that is reasonably good for a certain class of
configurations, although I have to say that for the original Corum
application of Tesla Coils, a lumped approximation gets you almost as
close, at much less work, considering the usual construction tolerances
in a tesla coil. *Modern Tesla Coil modeling is typically done with
either a lumped model or a FEM code that assumes it's axially symmetric
and often an assumed voltage distribution. The assumed distribution the
result of a combination of more detailed analytical modeling and some
experimental measurements on real coils, and speeds up the computation
drastically, while not adversely affecting the accuracy of the results
(that is, the changes are less than a few percent, comparable to
construction tolerances on these things).

73,
Tom Donaly, KA6RUH

You are correct in pointing out that a Tesla coil is a lumped
inductance. A "preponderance" of a lumped load disqualifies the use of
Maxwell's statements
The only metrics he supplied to justify the presence of equilibrium
were distributed loads and no more.
Regards
Art