Cecil Moore wrote in message ...


Yes, that's true. Now try it with a thin wire on HF. I believe what
you will find is that at the maximum reactance point, the resistance
is approximately half of the one-wavelength (anti)resonant value.
At the maximum reactance point, the resistance and reactance are
approximately equal. Since the maximum reactance value lies between
two points of pure resistance, doesn't it make sense that it might
be approximately where the resistance is half of the maximum value
of resistance?

That's pretty approximate, Cecil. From EZNec for a 10 meter 1mm diam
wire, I got about 2570+j2277 at 27.00MHz. The resistive and reactive
parts differ by over ten percent.

Be that as it may, if you evaluate the SWR tangency thing for a high
reference impedance, you will see that it's a GROSS error, not a tiny
one. You said it wouldn't change with changes in reference impedance,
but it does, and in a major way. Yes, the error is tiny for your
assumed 2500+j2500 evaluated against Z0 of 50 ohms, but the error is
huge if you evaluate against Z0 of, say, 2000 ohms.

And we're still back to not having said anything about _why_ the
reactance peaks at the frequency it does relative to the half- and
full-wave resonances.

Cheers,
Tom