interesting article - using angular momentum to increase bandwidth

[XConnect]

Hi all

There was an interesting discussion on the WAPA list (www.wapa.org.za) about whether the following technology was authentic. It suggests that different radio waves with different 'spins' (not polarisation) can increase the potential to broadcast on the same frequencies and therefore greatly increase the carrying capacity of spectrum.

You can download the full article (on the topic, including wifi tests) without a login at http://iopscience.iop.org/1367-2630/14/3/033001/article

New Science Journal is ‘peer reviewed’ which gives us hope that there is some substance to the article

Any substantive agreement or info to refute would be interesting.

 

[UnUnOctium]

Hmm, clever approach but I can't help but ask 2 questions:

1) It looks as if this is limited to directional, helical antennae due to the OAM property, so no application for omnidirectional antennae is possible?

2) I can't help but wonder how they orthogonalise the different OAM states. I find the statement that there's inherent orthogonality a bit false. They mention that the OAM are orthogonal to the propagation axis, which is true, but they also mention that it's mutually orthogonal without any proof. They mention that it's orthogonal in the Hilbert space but only the projections from a Hilbert space are mutually orthogonal.

IMO this needs a lot more detailed explanation, they seem to be avoiding the details.