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Old February 16th 10, 04:04 AM posted to rec.radio.amateur.antenna
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On Feb 15, 6:38*pm, Richard Clark wrote:
On Mon, 15 Feb 2010 14:07:35 -0800 (PST), JIMMIE

wrote:
What is/are "polarizations gains". That's a term with *which *I am not
familiar.


Hi Jimmie,

EZNEC, for one, reports antenna "gain"/directivity (re dBi) for each
polarization, azimuthum or elevation; or their sum as a total field
for a 3D model.

When two antennas (one receive, one transmit) are cross polarized, the
gain between them can vanish to zero. *In a real application this zero
is something larger, but still small like 30dB down compared to two
antennas employing the same polarization.

This last is observed in line of sight transmissions of VHF and above
(try hitting your favorite 2M repeater with the wrong antenna
polarization orientation). *It is not so common at HF as long paths
(aka skip) can blur the polarization (as can nearby reflectors for any
frequency) causing intermittant fading.

73's
Richard Clark, KB7QHC


A different perspective on polarization loss?

Jimmie
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Old February 16th 10, 07:44 AM posted to rec.radio.amateur.antenna
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On Mon, 15 Feb 2010 19:04:51 -0800 (PST), JIMMIE
wrote:

A different perspective on polarization loss?


Different? How? All pretty standard stuff.

As for different literal perspectives of polarization, I am sitting
here with two sets of 3D glasses for "Avatar" (just got back from the
IMAX version) and these two pair of glasses are very different from my
experience with Polaroid lenses of days gone by. And they are very
different from each other for the same movie.

The Real3D glasses at IMAX didn't work as normally worn, I still saw a
double image; but viewing the movie through the lenses backwards (ear
pieces going forward) rendered the IMAX 3D as 2D.

Now, when I sit here at the console and view the display (flat screen)
through the IMAX lenses, I can dim the display by rotating the pair.
One eye piece goes black at 45 degrees rotation, and the other eye
piece goes black at -45 degrees rotation. Flip them to look through
them backwards, and the same effect is observed.

When I take the Real3D pair and rotate them, only a slight shift in
hue: yellow tint in both lenses at 45 degrees rotation, and a blue
tint at -45 degrees rotation. When I flip them to look through them
backwards, I encounter a slight brightening for both lenses at 45
degrees rotation and a complete blocking for both lenses at -45
degrees.

I am familiar with display technology employing LCDs with double
polarization to increase contrast, and I could easily expect this from
the lenses of these two pairs of 3D glasses. Without having gone
further into researching it, I have a hunch that I am encountering
circular polarization here.

A little digging will tell.

73's
Richard Clark, KB7QHC
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Old February 16th 10, 08:23 AM posted to rec.radio.amateur.antenna
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On Mon, 15 Feb 2010 22:44:13 -0800, Richard Clark
wrote:

Without having gone
further into researching it, I have a hunch that I am encountering
circular polarization here.


Yep. RealD XL 3D is circularly polarized:
http://en.wikipedia.org/wiki/RealD_Cinema
http://en.wikipedia.org/wiki/List_of_RealD_films

"How to avoid getting a 3D headache while watching Avatar"
http://www.shadowlocked.com/index.php?option=com_content&view=article&id=70:ho w-to-avoid-getting-a-3d-headache-while-watching-avatar&catid=41:feature




--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
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Old February 16th 10, 09:25 AM posted to rec.radio.amateur.antenna
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In message
, Art
Unwin writes

Has there ever been a study that shows the relative consistency of
received signal polarity to see if it would be advantageous for multi
polarity receive antennas?


When I listen to the local 2m beacon ( horizontal polarisation) which
is north of me ,I get a strong reflection from something to the south
that turns the polarisation vertical. I noticed that while testing an
antenna in the garden.

Brian GM4DIJ
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Brian Howie
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Old February 16th 10, 12:52 PM posted to rec.radio.amateur.antenna
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On Feb 15, 6:55*pm, Art Unwin wrote:
I was basing efficiency on all forces being accounted for
with a higher gain resulting.


Whether or not you account for all forces will not have any
effect on gain. :/
This is another case of the hopeful free lunch..
But the cupboard was bare.
The radiation from the vertical and horizontal polarizations
added together will never end up being more than you started
with.
And an antenna that is a mix of both will be a compromise
if the other antenna is purely one way or the other assuming
no reflections, etc skewing the path.
No free lunch..





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Old February 16th 10, 08:13 PM posted to rec.radio.amateur.antenna
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Jeff Liebermann wrote:
On Mon, 15 Feb 2010 22:44:13 -0800, Richard Clark
wrote:

Without having gone
further into researching it, I have a hunch that I am encountering
circular polarization here.


Yep. RealD XL 3D is circularly polarized:
http://en.wikipedia.org/wiki/RealD_Cinema
http://en.wikipedia.org/wiki/List_of_RealD_films

"How to avoid getting a 3D headache while watching Avatar"
http://www.shadowlocked.com/index.php?option=com_content&view=article&id=70:ho w-to-avoid-getting-a-3d-headache-while-watching-avatar&catid=41:feature





Which makes perfect sense, since it means that if you tilt your head,
you don't swap images between left and right eyes. A very clever use of CP.
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Old February 22nd 10, 04:45 AM posted to rec.radio.amateur.antenna
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Model of 2 element multi polarization.

http://users.sdsc.edu/~unwin/art/Picture6.png
http://users.sdsc.edu/~unwin/art/Picture7.png
http://users.sdsc.edu/~unwin/art/Picture10.png
http://users.sdsc.edu/~unwin/art/Picture11.png
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Old February 22nd 10, 06:18 AM posted to rec.radio.amateur.antenna
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On Sun, 21 Feb 2010 19:45:03 -0800 (PST), Art Unwin
wrote:

Model of 2 element multi polarization.
http://users.sdsc.edu/~unwin/art/Picture6.png
http://users.sdsc.edu/~unwin/art/Picture7.png
http://users.sdsc.edu/~unwin/art/Picture10.png
http://users.sdsc.edu/~unwin/art/Picture11.png


I don't see a model. There is no .EZ, .GAA, .N4W or .NEC file for me
to play with and tear apart. I can't even tell what the antenna looks
like from what you've posted.

--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
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Old February 22nd 10, 06:44 AM posted to rec.radio.amateur.antenna
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On Feb 21, 11:18*pm, Jeff Liebermann wrote:
On Sun, 21 Feb 2010 19:45:03 -0800 (PST), Art Unwin

wrote:
Model of 2 element multi polarization.
http://users.sdsc.edu/~unwin/art/Picture6.png
http://users.sdsc.edu/~unwin/art/Picture7.png
http://users.sdsc.edu/~unwin/art/Picture10.png
http://users.sdsc.edu/~unwin/art/Picture11.png


I don't see a model. *There is no .EZ, .GAA, .N4W or .NEC file for me
to play with and tear apart. *I can't even tell what the antenna looks
like from what you've posted. *

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


You have two elements each located with x,y and z co ordinates at
each end, so you make your own file to suit the program you intend to
use or is available.
Surely you can model anything if you know the end locations of the
elements. If you are unable to do that then may be it is better that
you don't. There are to many programs around for me to make files for
every body and every program that is available so I supplied x,y,z co
ordinates which every body can translate.These are the points you
should look for to determine what the antenna looks like. Either way I
have supplied the results to save you the work.
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Old February 23rd 10, 01:20 AM posted to rec.radio.amateur.antenna
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On Feb 22, 3:45*am, Art Unwin wrote:
Model of 2 element multi polarization.

http://users.sdsc.edu/~unwin/art/Pic.../Picture11.png



and this proves what?
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