Re: OT: Distinguishable angular momentum in radio photons?

Posted by Fabio Lodrini on May 08, 2012; 1:46pm
URL: http://elecraft.85.s1.nabble.com/OT-Distinguishable-angular-momentum-in-radio-photons-tp7525974p7539185.html

Somewhere in internet there is (where ?) a video showing the experiment,
done in Venice during what it seems a Carnival event.
To me, it has a slight taste of a joke, included the strange parabolic dish.

I2LQF, Fabio

On 04/05/2012 8.25, Erik Basilier wrote:

> Oh, and the first thing I looked at was whether it was in the April issue.
> It was not. Maybe the IEEE got it from another publication's April issue?
>
> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of Erik Basilier
> Sent: Thursday, May 03, 2012 10:10 PM
> To: [hidden email]
> Subject: [Elecraft] OT: Distinguishable angular momentum in radio photons?
>
> The May 2012 issue of the IEEE Spectrum magazine reports that researchers in
> Italy and Sweden were able to conduct two separate instances of radio
> communication on the exact same frequency, without increasing bandwidth, and
> without time-division multiplexing, be making the transmissions differ in
> angular momentum. One transmission used linear polarization, and the other
> was given angular momentum by means of a dish with a radial cut, where the
> metal  was bent backwards/forwards on the two sides of the cut. Apparently
> this is not just a case of linear vs circular polarization, as circular
> polarization can be readily picked up by a linearly polarized antenna, and
> apparently the two channels did not interfere with each other. The
> researchers claim that this demonstration points to the possibility that the
> radio photons can be given multiple, quanized levels of angular momentum,
> making possible several more communication channels without increased
> bandwidth. Other researchers say that this is just a form of MIMO. Wikipedia
> describes MIMO as the technique of using multiple antennas as in diversity
> reception or in gain increases obtained by phasing the antennas.
>
>
>
> My apologies if this is too far OT.
>
>
>
> 73,
>
> Erik K7TV
>
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