art wrote:
It can be seen that a fixed radfiator hasd a primary frequency and
then some harmonic frequencies.
The spacing and the resonant points of an antenna resides in the
amount of resistance in the cuircuit
from zero upto a critical point as with a tank circuit. This
resistance value has the action of bringing the radiator
vibrational amplitude to zero where it then takes of to a diminishing
value compared to other componenents in the circuit to the point that
where the radiator is resonant the contained resistance has negnigable
effect.
Thus one can make a folded dipole with a variable resistance in the
radfiating circuit such that the main resonant point can be determined
as well as the spacing between the harmonic frequencies.
In addition, if the radiator consists of increased induntance designs
such as contra windings then the distance between the resonance point
and the harmonic points begin to decrease.
Thus using the above one can now make a all band antenna where the
resonance points line up with the desired frequencies.
An easy way to accomplish this is to wind wire on a dielectris from
end to end and back again several times
until one has wound at least two wave lengths on the former and then
feeding the arrangement at the beginning and ending wire points. Using
a mfj 259 one can then determine the spacings of the resonant point by
stretching the windins as well as adding the required variable
resister. Note. the resistance absorbs the energy between
resonance points and diminishes in effect as the point of resonance is
aproached. For more understanding of the radiation format of radiators
review the circumstances of voltage overshoot with respect to tank
circuits
The above will provide an alternate discussion thread that will take
away the current tunnel vision aproach
with respect to "black boxes" and bring the newsgroup back to the
advancement of antenna techniques if it is that that peeks one's
interests.

By the way, it is the ELECTROMAGNETIC field that launches the
particles from the radiating surface and it is the MECHANICAL REACTIVE
FORCE that provides the mechanical resonance of the radiator WHICH
JOINS THE THEORIES OF NEWTON AND . MAXWELL that Einstein struggled for
in vain.
For those that feel that mechanical laws of Newton cannot be used with
respech to electrical subjects( ala Roy) here is a chance for you to
prove your point.
Regards
Art Unwin, a limey no less

All multi-band antennas are a compromise. The only "all band antenna"
that exists is an isotropic radiator.

Smash wrote:

All multi-band antennas are a compromise. The only "all band antenna"
that exists is an isotropic radiator.

But the isotropic radiator doesn't exist. It's a theoretical construct.

Roy Lewallen, W7EL

On Dec 20, 5:45*pm, Roy Lewallen wrote:
Smash wrote:

All multi-band antennas are a compromise. The only "all band antenna"
that exists is an isotropic radiator.

But the isotropic radiator doesn't exist. It's a theoretical construct.

Roy Lewallen, W7EL

The best all band antenna I used was in my novice days... A 100 watt
light bulb on the end of a pair roughly 33 foot wires strung up
through a tree... Worked a dozen states one afternoon on 15 and 40,
then worked the locals on 80 that night... The Knightkit T-100 loaded
up just fine on that all band antenna... I don't think it was
isotropic, but it sure did blink when being keyed.. The neighbors
came over wondering why it was Christmas in September.... That was
cycle 19... What a great time we had...

denny / k8do

"Smash" wrote in message
...

All multi-band antennas are a compromise. The only "all band antenna"
that exists is an isotropic radiator.

not worth responding to art... but this statement is incorrect. an
isotropic radiator doesn't have to be 'all band' or even wide banded.
'isotropic' says nothing about frequency dependence at all, only about
directivity.

Dave wrote:
"Smash" wrote in message
...
All multi-band antennas are a compromise. The only "all band antenna"
that exists is an isotropic radiator.

not worth responding to art... but this statement is incorrect. an
isotropic radiator doesn't have to be 'all band' or even wide banded.
'isotropic' says nothing about frequency dependence at all, only about
directivity.

Kinda my point, actually... :-/