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 ______________________________________________________________ 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
