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Re: Lumped vs. T-line - You be the judge...



Tesla List wrote:
> 
> Original Poster: Terry Fritz <twftesla-at-uswest-dot-net>
>...
> No doubt about it, the waveform is distorted much like the T-line model
> would predict but far from exact.  Hardly a clean sine wave.  However,
> there is definitely a rise in the wave before the 720nS a T-line model
> would predict which the lumped model does predict.
> 
> So we see the fast output rise of the lumped model but distortions similar
> to the T-line model...  So the fast rise is definte proof of the lumped
> model and the distortions are proof of the T-line model...

The differences from the ideal transmission line are due to the fact
that a coil is not a TEM transmission line (a line where the electric
and magnetic fields are perpendicular to the direction of the line).
The magnetic coupling along the coil, predicted in the lumped model,
causes that initial rise. The transmission lines incorporated in
simulators, and treated in usual books, are all TEM models. They model
very well cables, but don't work very well for coils. Maybe a waveguide
model can be a better approximation.

Antonio Carlos M. de Queiroz