On Oct 24, 11:01 am, Mark wrote:
On Oct 24, 1:29 pm, wrote: On Oct 24, 6:48 am, Michael Coslo wrote:

Trying to make a "readers Digest" version here....

If I'm following so far:

The lowered frequency of resonance is due to changes in the velocity factor.

so as the wire gets thicker the C per unit length goes up at some rate
and the L per unit length goes down at some other rate, fine so that
reduces the characteistic Z by some rate....but none of that changes
the wave velocity as was pointed out above in the coax example.

I think the shortening effect may all be due to the extra C of the end
surface, i.e it iss end effect. For a thick wire, the end is a circle
that has C and this is all extra C that is not present for the thin
wire. Is this extra C alone enough to create the shortening effect?

Mark


No.
And, "end capacitance effect" is a poor model for what's really going
on. It's been used as an "explanation" for the observation that an
antenna that is slightly shorter than half a wavelength is resonant(as
in has no reactive component at the feedpoint). The problem is that an
infinitely thin dipole is resonant at less than 1/2 wavelength, and in
that case, there's no real "end" to have an effect.