On Aug 30, 7:21*pm, Jeff Liebermann wrote:
On Sun, 30 Aug 2009 14:54:05 -0700 (PDT), Art Unwin

wrote:
Tom, W8ji *apparently is an expert with antennas *having lectured
at Dayton and has authored many technical articles around antennas,
states that radiators must be straight for maximum efficiency,

He might have been talking about small antennas:

That may have been at the back of his mind but he did not stipulate
that

http://www.w8ji.com/radiation_resistance.htm
"Small antennas require extraordinary care to obtain high efficiency."

Very true for electrically small antennas with emphasis on
electrically.

The 2004 Dayton PowerPoint presentation is at:
http://www.w8ji.com/Dayton/Limited%20Space%20Antennas.ppt
Using Google, I couldn't find any statement resembling the "straight
radiators" claim.

I never said this is a quote from the Dayton lecture. Tom has numorous
dissertations with regard to antennas


Ummm... fractal antennas are anything but straight and have the best
gain for their size of any antenna.
http://www.fractenna.com
That is what Chip states for his company but I have no idea how a
fractal would work on top band. Most on this group deride the claims
of Chip with more than a handful of insults



Also, efficiency isn't everything. *For example, the efficiency of the
typical mobile HF antenna is fairly lousy because the antenna is a
small fraction of a wavelength long.

Exactly because it takes a WL or multiple there of to attain
equilibrium
*

Still, it's the best that can be
done on HF without trailing a long wire to a balloon, and dragging a
grounding plate. *

No. You are incorrect in my eyes! A multiple of a wavelength does
not require a ground plain and can be condensed into any shape or form
whilst retaining the required equilibrium. This is per the laws of
Maxwell when considering all forces involved in radiation for maximum
efficiency.
Regards
Art



http://www.k0bg.com/eff.html

--
Jeff Liebermann * *
150 Felker St #D * *http://www.LearnByDestroying.com
Santa Cruz CA 95060http://802.11junk.com
Skype: JeffLiebermann * * AE6KS * *831-336-2558

On Aug 30, 9:23*pm, Art Unwin wrote:

Exactly because it takes a WL or multiple there of to attain
equilibrium

Art -- how, then, do you account for the fact that a 1/4-wave monopole
and r-f ground system used by many AM broadcast stations produces
radiated fields that have been measured to be within a few percent of
the maximum possible for the applied power?

If "equilibrium" takes a WL or multiple thereof, why are such
fractional wavelength radiators so efficient?

RF

On Aug 31, 6:53*am, Richard Fry wrote:
On Aug 30, 9:23*pm, Art Unwin wrote:

Exactly because it takes a WL or multiple there of to attain
equilibrium

Art -- how, then, do you account for the fact that a 1/4-wave monopole
and r-f ground system used by many AM broadcast stations produces
radiated fields that have been measured to be within a few percent of
the maximum possible for the applied power?

If "equilibrium" takes a WL or multiple thereof, why are such
fractional wavelength radiators so efficient?

RF

One time response
Most hams are aware there are two basic resistances or impedances
involved in any antenna. The d.c. wire resistance is a constant
whether it is above ground or not.
Radiation resistance only occur when radiation is allowed to take
place which usually is considered above ground. When the circuit
cannot radiate such as in a ground plain or similar then the circuit
does not encounter radiation resistance thus the only resistance
encountered is the dc resistance which means it draws less power from
the source.
Thus for a half wave with ground plain it will draw 1/2 the power from
the source that a full wave will. So when talking about efficiency per
unit of energy supplied the only difference
between the two is the wire resistance that is not accompanied by
radiation which is extremely small. So overall efficiency changes of a
radiator is so small it really is of zero significance. What is
important is the ability of an antenna to radiate maximum strength
where you want and the ground plain applies a limitation which many
can live with.
The importance of efficiency is that one is accounting for all forces
that impact it where you enter a different mathematical areana which
opens up clues to the formation of radiation
and possibly other scenarios that can be of benefit in other areas.

A case in point. If one has a vertical then the radiation pattern is
donut shaped ie it has a hole that is devoid of radiation which is not
so good for military servalance. This is because the radiator is
oriented opposite to the gravitational force only. If one wants to
account for ALL forces involved then one must include with gravity the
Corriolis force without which NOTHING can be stable on Earth. One must
include it when considering the Earths forces within a arbitrary
boundary to achieve equilibrium. Thus to be in equilibrium a radiator
must be tipped to include the Coreolis force which then allows for a
spherical radiation pattern ala Poynting's vector where the forces
within the boundary equals ( and opposite) that outside the boundary
and is in a state of equilibrium Thus when a radiator is tipped it now
fills up the hole in the donut to obtain radiation that is equal in
all directions( equilibrium) which is what a military installation
would prefer as possible observation is 100 %. Thus starting with a
single radiator that is in equilibrium you are starting from a
different point to a planar mode when proceeding with array designs
which then becomes educational with respect to possible occurances
that are not available to systems outside that of the equilibrium.
NUFF SAID

Art Unwin wrote:

Thus to be in equilibrium a radiator
must be tipped to include the Coreolis force which then allows for a
spherical radiation pattern ala Poynting's vector where the forces
within the boundary equals ( and opposite) that outside the boundary
and is in a state of equilibrium Thus when a radiator is tipped it now
fills up the hole in the donut to obtain radiation that is equal in
all directions( equilibrium) which is what a military installation
would prefer as possible observation is 100 %
____________

Then by your theory does the radiation launched by a vertical, 1/2-
wave, center-fed dipole have a different pattern shape when that
dipole is tipped away from the vertical plane?

I'm referring to the radiation pattern of the dipole itself, not
including any reflections.

RF

"Art Unwin" wrote in message
...

snip a bunch of bafflegab... but now a real GEM! he was mumbling about
vertical antenna and the hole in the doughnut when they were vertical...

Thus when a radiator is tipped it now
fills up the hole in the donut to obtain radiation that is equal in
all directions( equilibrium) which is what a military installation
would prefer as possible observation is 100 %.

so now he has FINALLY defined his concept of "equilibrium"... read it
forever as isotropic! so his perfect antenna in equilibrium is isotropic or
has a gain of zero... to let him sum it up in his own words:

NUFF SAID

more than enough i would say!

This is because the radiator is
oriented opposite to the gravitational force only. If one wants to
account for ALL forces involved then one must include with gravity the

Gravity has no measurable effect on electromagnetic radiation.

Thus to be in equilibrium a radiator
must be tipped to include the Coreolis force

The coriolis force does not effect electromagnetic radiation.

which then allows for a
spherical radiation pattern ala Poynting's vector where the forces
within the boundary equals ( and opposite) that outside the boundary
and is in a state of equilibrium

How is the Poynting vector related to boundary conditions. What
boundary are you talking about?

Art Unwin wrote:

boundary to achieve equilibrium. Thus to be in equilibrium a radiator
must be tipped to include the Coreolis force which then allows for a
spherical radiation pattern ala Poynting's vector where the forces
within the boundary equals ( and opposite) that outside the boundary
and is in a state of equilibrium Thus when a radiator is tipped it now
fills up the hole in the donut to obtain radiation that is equal in
all directions( equilibrium) which is what a military installation

Ok, so this would mean that at every north or south latitude the angle
would be different, and at the equator would be zero, since there's no
coriolis effect there. Please give a table that shows the tip angle
versus latitude. (Bet you won't because it's secret) And at the north
or south pole it's not definable so antennas can't work there..

Why haven't you mentioned these facts before? Bet you haven't because
you didn't think of it, but you'll claim otherwise or just not respond.

tom
K0TAR

"Art Unwin" wrote in message
...
Tom, W8ji apparently is an expert with antennas having lectured
at Dayton and has authored many technical articles around antennas,
states that radiators must be straight for maximum efficiency,
apparently

Art,
The only place I have ever read that on Tom's site is related to Beverage
antennas- the statement is true, and for obvious (to most of us) reasons.

Dale W4OP

On Aug 30, 7:27*pm, "Dale Parfitt" wrote:
"Art Unwin" wrote in message

...

Tom, W8ji *apparently is an expert with antennas *having lectured
at Dayton and has authored many technical articles around antennas,
states that radiators must be straight for maximum efficiency,
apparently

Art,
The only place I have ever read that on Tom's site is related to Beverage
antennas- the statement is true, and for obvious (to most of us) reasons.

Dale W4OP

I know it is considered as obvious to those who resist change.
Obvious as you stated means that there is no possible alternative
available because all is known.

"Art Unwin" wrote in message
...
On Aug 30, 7:27 pm, "Dale Parfitt" wrote:
"Art Unwin" wrote in message

...

Tom, W8ji apparently is an expert with antennas having lectured
at Dayton and has authored many technical articles around antennas,
states that radiators must be straight for maximum efficiency,
apparently

Art,
The only place I have ever read that on Tom's site is related to Beverage
antennas- the statement is true, and for obvious (to most of us) reasons.

Dale W4OP

I know it is considered as obvious to those who resist change.
Obvious as you stated means that there is no possible alternative
available because all is known.

Well, suppose you show us for a given length Beverage antenna, how
configuring it in any other shape but straight makes it a better Beverage.

Dale W4OP