Phase array question
 

Jim Kelley wrote:
Cecil Moore wrote:
What is wrong with you?

Glutton for punishment I guess. Thanks for asking.

Many years ago, five or more, I agreed with you that power
doesn't flow. Yet, more than a dozen times in the ensuing
years, you have accused me of believing that power flows.
I denied it every time, yet you did it again this very month.

Many months ago, I revised my energy article based on your
inputs. Yet, you continue to accuse me of promoting a "4th
mechanism for reflection caused by interference".

Incidentally, whether interference causes reflections or
not certainly depends upon the definitions of "interference"
and "reflection" which seem ill-defined to start with.

Whether your rraa behavior is deliberate or not, it points to
a personality disorder of some kind. I cannot find "glutton
for punishment" in the "Diagnostic and Statistical Manual of
Mental Disorders" but maybe you can plead 302.83 or 302.84.
--
73, Cecil http://www.w5dxp.com

Phase array question
 

Cecil Moore wrote:
Many months ago, I revised my energy article based on your
inputs. Yet, you continue to accuse me of promoting a "4th
mechanism for reflection caused by interference".

Not everything is an accusation, Cecil. Please stop with the
melodramatics act. You wrote that bit about the 4th Mechanism of
Reflection in your paper against every bit of advice I had given you for
months. Buck up and take responsibility for your yourself for once.

73, ac6xg

Phase array question
 

Jim Kelley wrote:
You wrote that bit about the 4th Mechanism of
Reflection in your paper against every bit of advice I had given you for
months. Buck up and take responsibility for your yourself for once.

I bucked up and took responsibility 6 months ago.
When are you going act like a man and let it go?
--
73, Cecil http://www.w5dxp.com

Phase array question
 

Cecil Moore wrote:
Jim Kelley wrote:
You wrote that bit about the 4th Mechanism of Reflection in your paper
against every bit of advice I had given you for months. Buck up and
take responsibility for your yourself for once.

I bucked up and took responsibility 6 months ago.

I missed your retractions. If you wouldn't mind, please repost them.
Thanks very much.

73 ac6xg

Phase array question
 

Jim Kelley wrote:
Cecil Moore wrote:
I bucked up and took responsibility 6 months ago.

I missed your retractions. If you wouldn't mind, please repost them.
Thanks very much.

One more time: "[10] Revision 1.1, Feb. 20, 2008 - In the
original version, the redistribution of energy due to wave
cancellation was dubbed a "reflection". W5DXP has dropped
that designation in favor of a "redistribution" as described
by the FSU web page. The word "reflection" is reserved for
describing something that happens to a single wave when it
encounters an impedance discontinuity. The word "redistribution"
of energy is adopted for describing what happens to the energy
in canceled waves. In like manner, since interference can occur
with or without wave cancellation, any reference to interference
as the cause of the redistribution of energy has been removed."
--
73, Cecil http://www.w5dxp.com

Phase array question
 

"Roy Lewallen" wrote in message
treetonline...
Not directly. What counts (considering the simple case of two elements) is
the magnitude and phase of the current in the other element, and their
spacing, orientation, and lengths.

Understood, thanks.

But your search for small, broadband antennas puts you bump-up against the
principle "small - broadband - efficient, choose any two".

Yeah, some years ago I read Wheeler's 1947 paper on the fundamental limits
there (although one of my old professors, James McLean, was fond of mentioning
how many peoples' interpretation of that paper wasn't quite right... and he
wrote his own take on it back in 1996). In my case, I intend to use the usual
folding techniques to obtain significantly greater overall length than what
I'm allowed in any one dimension. When I look at such "meander line"
antennas, though, it's often not clear to me if the designer took coupling
between the folds into account or not, or instead just used some rules of
thumbs to avoid "significant" coupling and then empirically trimmed the
antenna to get the input impedance they were after.

The book I'd go to for researching the possibilities would be Lo & Lee's
_Antenna Handbook_.

Four volumes... wow!

You might also get some ideas from Bailey, _TV and Other Receiving
Antennas_, since TV antennas have to be pretty broadband.

That I have a copy of... I think I got it a few years ago when the topic of
how "rabbit ear" TV antennas actually "work" was being discussed. (These days
I think of them as similar to a tapered slot antenna, which is wideband.)

Thanks,
---Joel

Phase array question
 

Interesting paper on how the fundamental limits on the Q of antennas applies
to real-world devices: http://www.centurion.com/home/pdf/wp...ion_limits.pdf --
some antennas perform better than one might initially predict based on
coupling to adjacent ground planes (etc.) that effectively make the antenna
electrically larger than initially intended!

Phased array question
 

Ahhhhhhhh. That's better.

Ed, NM2K

Phase array question
 

Joel Koltner wrote:
"Roy Lewallen" wrote in message
treetonline...
Not directly. What counts (considering the simple case of two elements) is
the magnitude and phase of the current in the other element, and their
spacing, orientation, and lengths.

Understood, thanks.

But your search for small, broadband antennas puts you bump-up against the
principle "small - broadband - efficient, choose any two".

But actually, that's not the principle.. The actual limits have to do
with the ratio of stored energy vs radiated power in the antenna (Q, in
the energy storage sense, not in the "resonant circuit" sense). For
example, a lot of the efficiency issues in practical antenna systems are
more to deal with the reactive component of the feedpoint impedance, and
the reactive/lossy network used to make it look like the feedline or
transmitter output impedance.

And the classical formulation also makes some not necessarily always
valid assumptions: linearity and reciprocity of components being the
notable one (Foster vs non-Foster terminations, for instance).

Phase array question
 

On Tue, 19 Aug 2008 09:17:01 -0700, Jim Lux
wrote:

But your search for small, broadband antennas puts you bump-up against the
principle "small - broadband - efficient, choose any two".

But actually, that's not the principle.. The actual limits have to do
with the ratio of stored energy vs radiated power in the antenna (Q, in
the energy storage sense, not in the "resonant circuit" sense).

Hi Jim,

Different meanings of Q? The measure of Q may vary according to
arbitrary usage: the choice of SWR limits to define bandwidth which
infers Q. Some choose 2:1, classic Q would go further. Either way,
and for either quantitative result, the meaning of Q remains
essentially the same.

For
example, a lot of the efficiency issues in practical antenna systems are
more to deal with the reactive component of the feedpoint impedance, and
the reactive/lossy network used to make it look like the feedline or
transmitter output impedance.

That isn't Q, that is matching considerations. Certainly there is a Q
for the system and Q can be extremely high in detriment to getting
transmitting power out of the antenna. This is, albeit, a largely
unattainable situation, but try sending voice communications through a
very efficient 1M loop at 160M.

73's
Richard Clark, KB7QHC