Richard Harrison wrote:

Amos Keag wrote:
"But, what does feedpoint impedance have to do with resonance?"

Imagine a whip worked against ground. It is resonant at 1/4-wavelength
where it presents a low impedance. It is resonant again at
1/2-wavelength where it presents a high impedance.

Best regards, Richard Harrison, KB5WZI


Resonance has NOTHING to do with impedance. Resonance is resonance; it
has a harmonic response.

Feed point impedance is the load presented to a transmission line when
you want to make a wire, any wire, resonant or non resonant, into an
antenna. I can feed any antenna with a single wire against ground, I can
feed the same antenna with 50 ohm coax, 70 ohm coax, 90 ohm coax, 72 ohm
balance line, 300 ohm balanced line 450 ohm balanced line 600 ohm
balanced line. None of these transmission lines changes to resonance or
non resonance of the antenna.

Resonance is determined by the physical characteristics of the antenna.
Generally these include the antenna length and the length to diameter
ratio. PERIOD.