No. The example with the positive reactance is at a frequency below
parallel resonance, where the reactance goes the other way than it does
just below normal resonance.

As I pointed out in my most recent posting, the antenna reactance
becomes more negative at frequencies just below resonance, and the
transmission line reactance more positive. Beginning at resonance, the
net feedpoint reactance (the reactive part of the parallel combination
of the antenna and transmission line impedances) becomes more negative
as frequency decreases or the antenna gets shorter -- until parallel
resonance is reached. At parallel resonance, the reactance abruptly
jumps from a large negative value to a large positive value, then
decreases as frequency further decreases or the antenna shortens. The
example I gave in that posting showed the parallel resonance at a
frequency somewhat higher than where the antenna is an eighth wave high.
But the earlier example antenna with 46.1 + j1893 ohm feedpoint Z is
about an eighth wave high, shorter than self resonance. Don't forget
that the actual frequency of parallel resonance depends on the impedance
of the transmission line, so don't make generalizations about where
parallel resonance will occur for all antennas. But if you know that the
folded monopole or dipole is shorter than a resonant length and its
feedpoint reactance is positive, it's below parallel resonance and the
reactance will decrease as frequency drops or the antenna gets shorter.
If its feedpoint reactance is negative, it's above parallel resonance
and the reactance will become more negative as the frequency drops or
the antenna becomes shorter.

An unfolded monopole's impedance is monotonic below resonance. That is,
the resistance drops and the reactance becomes more negative as you go
lower in frequency, as far as you want to go. Not so with a folded
monopole -- it has one behavior down to the parallel resonant point,
then the magnitude of the reactance goes the other way below that. The
reason is that there are two separate mechanisms at work, rather than
the single one for an unfolded monopole. So if you want to make a rule
about which way the reactance goes, you've got to specify whether you're
above or below parallel resonance.

Roy Lewallen, W7EL

Richard Harrison wrote:
John wrote:
"What Roy is saying is also what I`m seeing with EZNEC. You are saying
the opposite reactance occurs with a folded monopole."

On Fri. Apr. 23. 2004, 4:19 pm (CDT-2) Roy Lewallen wrote:
"This can be resonated as Richard Harrison recently pointed out, with a
series capacitor."

Why? look above in Roy`s posting:
"---EZNEC shows a feedpoint impedance of 46.1 + j1893 ohms."

The + j1893 is inductive, not capacitive. It`s the reactance shown by a
too short (less than 1/4-wave) folded monopole or short-circuit stub.

I believe I am on the same page with Roy.

Best regards, Richard Harrison, KB5WZI