I read a fairly comprehensive debunking of this some weeks/months ago, I just wish I could remember where I read it, it might have been in one of the physics publications I take at work, now probably buried under mounds of other stuff!
I seem to recall that it picked up on pretty much the same points as Jussi has written. If I can find the source, I will post a link to it. 73 Stephen G4SJP On 4 May 2012 20:02, Jussi Eloranta <[email protected]> wrote: > On 05/03/2012 10:10 PM, Erik Basilier wrote: > > 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. > > > The only source of angular momentum in a photon is its intrinsic spin ( > = 1). This can have two projections, +1 and -1 (only two, unlike for > most spin one particles, which have three possible projections). > However, these two projections are directly related to the left and > right circularly polarized light, so I cannot quite see what other > source of angular momentum could arise in this case? Having said this, I > don't quite believe in the Swedish group explanation of this experiment. > > Jussi Eloranta > AA6KJ > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
