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Author Topic: Vortex / orbital angular momentum rf comms- is it real?  (Read 94 times)

Weaver

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Vortex / orbital angular momentum rf comms- is it real?
« on: June 30, 2018, 01:20:15 AM »

I have read some stuff about recent trials of something variously called ‘vortex’ or orbital angular momentum radio-frequency comes which its promoters claim could offer vastly greater speeds by allowing a new kind of modulation which is orthogonal to existing methods and would allow multiple data streams to be sent in top of the same current channel. Some accounts if it seem to be simply talking about rotating polarization which rotates at various rates. If that is it I don't see how this is going to give the huge benefits claimed. The stuff about ‘orbital angular momentum’ sounds like quantum mechanics terminology borrowed from a chapter of a book about electrons in atoms, and I cannot for the life of me think what this has to do with photons, the subject of the comms being described. It may just be that it is being really badly described. Rotating polarization at different rates is an interesting idea but I am not at all sure where it gets you. Other kinds of diversity could explain some the the early experimental results.

Does anyone else know if this is real or all nonsense? The next cold fusion-type scam?

We have a similar situation with the EM drive which if it is real could make interplanetary travel cheap.
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banger

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Re: Vortex / orbital angular momentum rf comms- is it real?
« Reply #1 on: June 30, 2018, 02:07:26 AM »

I am always interested in new concepts. As you say radio frequency does this apply to Wifi or Radio stuffed down copper. As far as I am aware BT is rolling out optical.
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Tim
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Weaver

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Re: Vortex / orbital angular momentum rf comms- is it real?
« Reply #2 on: June 30, 2018, 02:37:52 AM »

They have done experiments using RF over air, not in copper. However I do nit see the difference, you are just shining em fields down the inside of some copper when it comes down to it, instead of air.

One experiment that I saw simply unvolved an ordinary parabolic dish aerial that had been butchered and a cut was made radially our from the centre while the outer edge was pulled forward, so the whole thing had a twist, like a slice of a helix, that was the idea. The claim is that different angles around the x axis, that is in the y-z plane, would have different phase associated with them because of the forward displacement if the dish surfaced varying with angle.
This makes no sense to me at all. Indeed you will have some kind of helix-shaped wavefronts coming of the thing but I do not see what that has to do with polarisation. And has shift modulation of any kind is hardly a panacea - we already have PSK that alters phase to carry information so that avenue is already exploited. One commentator said that the butchered disk was simply an example of spatial diversity, and we already have MIMO and various techniques allowing orthogonality to be exploited.
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