"Cecil Moore" ha scritto nel messaggio
...

A 1/4WL monopole is half of an antenna. The ground plane
is the other half. The feedpoint is at a current maximum
point which is a magnetic field maximum. The high intensity
magnetic field directly encountering the earth is a lossy
condition.

A 1/2WL monopole is a complete resonant antenna. The
feedpoint is at a voltage maximum point which is an
electric field maximum. A pure electric field encountering
earth ground is less lossy than a pure magnetic field
encountering earth ground. Since the feedpoint impedance
is very high, some hams simply use a ground rod for a
counterpoise.

First thanks for replies abt the 5/4 WL monopole, i'm trying right now to
use eznec and simulate what you saw me.
One more newbie question: 1/4 WL and 1/2 WL monopoles are both end feeded.
So my feed point is exactly at the begin of monopole.
Assuming there is no feed line, or also a 1/2 WL feed line (if IIRC 1/2 wl
is the line lenght that preserve the phase of my RF wave from generator to
the end of the line...) what decide if i'm feeding the antenna on a current
maximum point or in a voltage maximum point ?? On a dipole, with the imagine
of the wave "superimposed" to the dipole in my mind, is quite easy for me
figure out if i'm feeding it on a current node or on a voltage peak (e.g
center feed vs. off center feed dipole). But since in both 1/4 and 1/2 wl
monopoles i'm at the *begin* of the antenna, what decide the feed point
modality (I or V) ?? The impedance i have at the specific point ??

Regards,
-.-. --.-., Cristiano, Italy.

"-.-. --.-" ha scritto nel messaggio
...
Assuming there is no feed line, or also a 1/2 WL feed line (if IIRC 1/2
wl is the line lenght that preserve the phase of my RF wave from generator
to the end of the line...)

Oops. Sorry.
1/2 wl feed line preserve the impedance seen at both ends of the line. Not
sure about phase.

-.-. --.-

-.-. --.- wrote:
... what decide the feed point
modality (I or V) ??

1/4WL down from the tip is a current maximum point.
1/2WL down from the tip is a voltage maximum point.
3/4WL down from the tip is a current maximum point.
4/4WL down from the tip is a voltage maximum point.
5/4WL down from the tip is a current maximum point.

i.e., odd multiples of 1/4WL are current maximums.

i.e., even multiples of 1/4WL are voltage maximums.
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com

"Cecil Moore" ha scritto nel messaggio
...

5/4WL down from the tip is a current maximum point.
i.e., odd multiples of 1/4WL are current maximums.

i.e., even multiples of 1/4WL are voltage maximums.

Yep
My error is seeing RF "flowing" from my feed point only through the monopole
and up , not considering that an RF generator is a bipolar thing, and
feeding an antenna is ever related in respect both begin and end of the
entire antenna.
In case of my monopole, i simply forget about the other part of my antenna

Sorry for the dumb question. Hope to ask more serious things.

73,
-.-. --.-, Cristiano, Italy.