Art, KB9MZ wrote:
"It does not mean that a radiating antenna which is in the parallel
configuration will have a high impedance."

Parallel configuration can mean several things. I will take it to mean
the antenna shares some of the characteristics of a parallel resonant
circuit.

Experience is that an end-fed 1/2-wave antenna has a high feedpoint
resistance while an end-fed 1/4-wave antenna has a low feedpoint
resistance. Since Art is hunting discrepancies, 1/2-wave and 1/4-wave
are only approximate wavelengths. Resonant lengths in an antenna are
shorter than free-space wavelengths due to reduced velocity along a wire
and due to capacitive effects near the open-circuit at the end of the
wire.

For a given power input to the antenna, the feedpoint voltage rises as
the feedpoint impedance rises. See Ohm`s law.

In 1949 I worked in a broadcast plant where two stations shared the same
tower. Both had frequencies, 950 KHz and 1320 KHz, that were higher than
the 1/4-wavelength frequency of the tower which was designed for the
previous occupant of the plant. Its frequency was around 740 KHz. The
1/2-wave resonant frequency of the tower might have been around 1480
KHz. The high length of the tower was still enough to make it a high
impedance at its operating frequencies. 1320 KHz is emanating from that
that tower as I type. It is hot as a pistol. Big arcs can be drawn at
the base of the tower.

Art`s question was: "What is it about parallel circuits that makes them
unsuitable?"

Like Johnny Carson, I may have given the answer before revealing the
Question. A parallel resonant circuit shares the high impedance trait
with an end-fed wire near 1/2-wave long.

A series resonant circuit shares the low impedance trait with and
end-fed wire near 1/4-wave long.

A 1/4-wave series resonant circuit antenna with an open-circuit end
produces a low impedance at its driven end through an impedance
inversion caused by the reflected energy arriving back at the drive
point. Radiation and other resistance prevent the reflected wave from
causing a complete short-circuit at the drive point.

When I say a radiating antenna in the parallel configuration (Art`s
words) will have a high impedance (the 1/2-wave repeats high impedance
caused by the open circuit), it will mean that its radiation resistance
has grown with its length and its reactance will be zero if the antenna
length has reached 2nd resonance, or the reactance is non-zero between
resonant lengths.

High and low are relative terms. The questions should be, how high? or
how low?

Best regards, Richard Harrison, KB5WZI