A helically-wound dipole or monopole that is physically short in terms
of a free-space wavelength can be made electrically resonant at its
input terminals as a result of the inductance of the helical form of
the radiating conductor.

But that does not mean that it has all of the electrical
characteristics of a linear conductor that is inherently resonant,
without the need for inductive loading.

The radiation resistance of such a helically-wound radiator can be
much lower than a naturally resonant radiator, which can mean that the
percentage of transmitter power radiated by the antenna SYSTEM can be
much lower than when a naturally resonant radiator is used.

The link below leads to a page developing this point from Kraus'
Antennas For All Applications, 3rd Edition.

http://i62.photobucket.com/albums/h8...ndVertical.gif

RF

"Richard Fry" ha scritto nel messaggio
...

But that does not mean that it has all of the electrical
characteristics of a linear conductor that is inherently resonant,
without the need for inductive loading.

Yes, replying to Richard but also to Roy and Dave.. maybe i can't explain
very well, but the sense of my latest question is this:

if a half wave end-fed *monopole* antenna have the following primary
characteristics (if IIRC):

- High Z at the feedpoint (voltage maximum and current node);
- very small counterpoise lenght compared to the resonant wavelenght of the
antenna (typical 0.1-0.2 lambda)

can i mantain the same characteristics shortening the antenna in any way ??

Thanks for read and explain to those who want clarify my doubts.

-.-. --.-

Richard Fry wrote:
A helically-wound dipole or monopole that is physically short in terms
of a free-space wavelength can be made electrically resonant at its
input terminals as a result of the inductance of the helical form of
the radiating conductor.

But that does not mean that it has all of the electrical
characteristics of a linear conductor that is inherently resonant,
without the need for inductive loading.

The radiation resistance of such a helically-wound radiator can be
much lower than a naturally resonant radiator, which can mean that the
percentage of transmitter power radiated by the antenna SYSTEM can be
much lower than when a naturally resonant radiator is used.
. . .

But a helically-wound radiator *is* a naturally resonant radiator if
wound to make it so. It just isn't straight.

Roy Lewallen, W7EL