On 4 Jul, 05:14, "Richard Fry" wrote:
"art" wrote... I have always stated and proved. "The radiator can be
any shape or size or angle etc.as long as it is in equilibrium
and resonant which is buried in the laws of the masters"

____________

A distinction needs to be made between the ability of a conductor of any
size/shape to efficiently produce EM fields from the r-f current flowing
along it, and the capability of the associated transmitter and transmission
line to deliver that r-f current.

A good conductor of EVERY size/shape (including even a point source) will
radiate virtually ALL the r-f power that can be made to flow into it --
which quantity equals the product of the square of the r-f current at the
feedpoint, and the resistive term of the impedance there (ie, the radiation
resistance).

If the radiating structure (antenna) is not self-resonant, there will be an
impedance mismatch between it and the transmission line connected to its
feedpoint. This means that the antenna will not accept all of the
transmitter power that could be delivered it to by the transmission line.
But whatever power does transfer into the antenna will be radiated with the
same high efficiency as if the match was perfect.

There are many examples of non-resonant (highly reactive) antenna structures
that, with proper system design, radiate a very high percentage the power
available from the transmitter. Common examples of this are the monopole
radiators used by MW AM broadcast stations -- very few of which are
self-resonant.

High radiation efficiency is achieved in these non-resonant antennas by the
use of a matching network at the antenna feedpoint, which cancels the
reactance of the monopole, and transforms the r-f resistance term there to
match the Zo of the transmission line in use.

This results in an impedance match capable of passing nearly all the power
available from the transmission line, despite the fact that the antenna
itself remains non-resonant, and without setting up high standing waves on
the transmission line.

The only significant losses.then are the attenuation of the transmission
line, the loss in the matching network, and the loss in the r-f ground
system. In normal broadcast station practice these losses are small enough
for the groundwave field at 1 km to be 90% or better of the theoretical
value for a perfect radiator of that electrical height and applied power,
over a perfect ground plane.

Bottom line (N.B. Art): antennas do not need to be resonant to perform as
very efficient radiators.

RF

All very true. But the bottomline is not just efficient antennas but
also
having the radiation field where you want it at an inexpensive way,
that is compatible with your lot size and in cluster form i.e. array.
The antenna from the University is resonant tho less efficient than
ideal
But many hams with small lots place in high esteem an antenna that tho
a
bit less in efficiency gets the job done. But with all that said
I have no problem with anything that you have stated. Lets face it,
if a ham can get on the air with a small antenna tho losses may be 1-2
db
he has achieved all he wanted to do and other hams who are positioned
in the right
places will certainly view his signal as an equal.
Best regards
Art

"art" wrote
The antenna from the University is resonant,
tho less efficient than ideal.
_________________

Reprise for Art: The efficiency of an antenna system in radiating the
power available at the antenna end of the transmission line connected to its
feedpoint does not depend on whether or not the radiator itself is naturally
resonant.

It depends on...

1) the ratio of the radiation resistance of the radiating sections of the
antenna to the sum of that radiation resistance with all other r-f
resistances in the antenna system. The pure radiation resistance of an
antenna depends on the effective length//configuration of, and the r-f
current distribution along the conductors exposed to space -- but not those
of any matching devices used in the system design (wherever located).

2) the degree of impedance match existing between the antenna feedpoint and
the source (normally, a transmission line, including any matching network
there).

The DLM uses matching components within the length of a short vertical
radiator with the goals of canceling the high capacitive reactance of this
electrically short radiator, and changing the current distribution along the
radiator for an average value higher than provided by base loading.

So for the same losses in the r-f ground system, the DLM could have somewhat
better system radiation efficiency than a base-loaded monopole of the same
physical height. But good system efficiency would still be heavily
dependent on the quality of the r-f ground used with it (just as in a
"standard" monopole).

This is not a revolutionary concept, as mid- and top-loading techniques have
been used with vertical monopoles for many decades.

RF

On 4 Jul, 08:14, "Richard Fry" wrote:
"art" wrote The antenna from the University is resonant,
tho less efficient than ideal.

_________________

Reprise for Art: The efficiency of an antenna system in radiating the
power available at the antenna end of the transmission line connected to its
feedpoint does not depend on whether or not the radiator itself is naturally
resonant.

It depends on...

1) the ratio of the radiation resistance of the radiating sections of the
antenna to the sum of that radiation resistance with all other r-f
resistances in the antenna system. The pure radiation resistance of an
antenna depends on the effective length//configuration of, and the r-f
current distribution along the conductors exposed to space -- but not those
of any matching devices used in the system design (wherever located).

2) the degree of impedance match existing between the antenna feedpoint and
the source (normally, a transmission line, including any matching network
there).

The DLM uses matching components within the length of a short vertical
radiator with the goals of canceling the high capacitive reactance of this
electrically short radiator, and changing the current distribution along the
radiator for an average value higher than provided by base loading.

So for the same losses in the r-f ground system, the DLM could have somewhat
better system radiation efficiency than a base-loaded monopole of the same
physical height. But good system efficiency would still be heavily
dependent on the quality of the r-f ground used with it (just as in a
"standard" monopole).

This is not a revolutionary concept, as mid- and top-loading techniques have
been used with vertical monopoles for many decades.

RF

The term " cancelling " is not correct tho people seem to be happy
with it.
In fact is it is not CANCELLING anything as it is actually adding to
provide
a state of equilibrium. Big difference
Art

"art" wrote

The term " cancelling " is not correct tho people seem to be happy
with it. In fact is it is not CANCELLING anything as it is actually
adding to provide a state of equilibrium. Big difference.
_____________

That's what you meant by equilibrium !

Kindly note that "equilibrium" (or resonance) does not need to be an
attribute of the radiator itself, only a desirable attribute of the complete
antenna system.

RF