Reg Edwards wrote:
What do you mean by "true" length?


You know very well what I mean. Have you nothing else better to do
with your time?

No, I don't know what you mean. And your response doesn't give me a
great deal of confidence that you do, either.

The reactance of an infinitely thin half wavelength dipole is 42.5 ohms,
meaning that it isn't resonant. An infinitely thin dipole of length
0.496 wavelength, or about 1% shorter, is resonant. So my first question
is whether the "true length" of an infinitesimally thin resonant dipole
is 0.496 or 0.5 wavelength. (If 1% is too little to quibble about, why
are we concerned about a length difference of a wire diameter?)

If we increase the diameter of the antenna to 1/50 its length, the "true
length" would then be 1.02 times the "true length" of the
infinitesimally thin dipole. Yet we have to reduce the antenna length by
nearly 7% to maintain resonance. So the "true length" doesn't have
anything obvious to do with resonant length, nor does it provide a way
to predict the resonant length based on wire diameter.

If the meaning of "true length" is obvious, most other readers must know
what it means. Would someone please be so kind as to explain to me what
it means and how it's used?

Roy Lewallen, W7EL