Twisted Radio Beams Could Untangle the Airwaves

Urchin writes "The radio frequency spectrum available for wireless communication is becoming increasingly crowded thanks to new wireless technology. A solution to the shrinking space might be to put a spin on radio beams during their transmission, to produce a twisted beam, according to Swedish physicists. In theory, huge amounts of data could be sent in the pitch of the twist, which is distinct from the amplitude and frequency of radio waves — the features used at the moment to send information."

Comments

Re:in this house we obey shannon's theorem

[ceoyoyo]

Shannon's law is a tricky piece of work. It doesn't actually tell you how much data you can transmit given a particular amount of bandwidth. It tells you how much data you can transmit given a particular amount of bandwidth and particular noise characteristics over a given channel.

Now, you can play various games with that. If you limit yourself to, say, frequency modulation, you just measure the noise, run it through Shannon, and get your result. But what if you polarize the signal and encode data in that? Have you broken Shannon's law? No. You can account for things like that by counting it as a separate channel, or by changing your noise estimate to account for the additional, independent modulation technique.

These guys' modulation technique is another independent channel.

The article does say it's probably not going to work very well for things like cell phones though, since you need an antenna array. It might be useful for things like microwave towers though.

NOT 140 years late

[Doug Merritt]

Nope, that's not what they're doing; it's not polarization. They're using physics that wasn't even discovered until 1992.

See http://www.physics.gla.ac.uk/Optics/play/photonOAM/