Cecil Moore wrote:
Gene Fuller wrote:
Second, your analysis is utter rot! Are you suggesting that if the
coil can be made resonant at some frequency, and then you cut it in
half, that it still behaves the same?

No, it behaves approximately like half of the original
coil tending to have approximately the same Z0 and VF as
the original coil. The phase shift through the coil will
tend to be approximately 1/2 of the original phase shift -
not exact because of end effects.

Let's say we have a 1/4WL helical antenna with an obvious
phase shift of 90 degrees. If we cut that helical in half,
it is likely to have a phase shift of approximately 45
degrees, nowhere near the 4.5 degrees that W8JI has
"measured".

If we add a stinger to the above half-coil, we will have
a base-loaded antenna. The phase shift will be relatively
close to 45 degrees at the same frequency. The stinger
contributes another few degrees. The impedance discontinuity
between the coil and stinger contributes the rest of the
90 degrees of electrical length.

Cecil,

It appears you missed the primary message of the Corum article. He is
completely denying the simple concept you wrote above. He argues that
there is a very special effect near resonance. You cannot simply cut the
coil in half and expect the same behavior.

Frankly, I have little interest in Tesla coils, and I don't know or care
if Corum is right or wrong. I do believe, however, that it is a bit
careless for you to pick and choose equations from the article, ignore
the caveats, and then go ahead and misuse those equations.

73,
Gene
W4SZ