-.-. --.- wrote:
"Token" ha scritto nel messaggio
...

The antenna is electrically a half wave on 10M to 40M, the electrical
length of an element is not directly related to it's physical length.
That is how they make a "halfwave" in a stick shorter than a physical
quarter wave.

Ok... could you please explain me how i can build an, e.g., electrical half
wave for the 20 meters in a 3 meters stick ??

I repeat, i'm a great newbie on antenna theory and related arguments, so the
question i pose to you now is not ironic but really posted to increase my
knowledge, if is possible.

Thanks in advance also to other people that may contribute to this question.

-.-. --.-

"Electrical half wave" doesn't have much meaning when applied to an
antenna, so there isn't a good answer to your question. There's no way
to make a short dipole behave exactly like a half wavelength dipole in
all respects. But if you mean you want to make a short antenna resonant
(one of the properties of a physically nearly half wavelength dipole),
you can make it or an antenna of any physical size or shape resonant by
putting an impedance transforming (matching) network at the feedpoint.
Presto, a resonant antenna. If you want the same feedpoint resistance at
resonance as a physical half wavelength antenna, you can get that too by
adjusting the network component values. The pattern of a dipole of any
length shorter than a half wavelength will in practice be
indistinguishable from that of a half wavelength dipole. What will
happen is that you'll have increased loss due to the larger currents and
voltages in the shorter antenna and the matching network, the amount
depending on the design. And if the losses are kept reasonable, the
bandwidth of the shorter antenna will be narrower than the bandwidth of
a half wavelength antenna.

Roy Lewallen, W7EL