Twisting more bandwidth out of spectrum

This article was authored by John C. Tanner, and was originally posted on telecomasia.net.

One of the hot topics in the mobile sector is spectrum – how to get more of it and how to get more out of the spectrum you already have. For the latter, one technological solution could be to give radio waves a good twist – literally.

Recent research led by Italian astrophysicist Fabrizio Tamburini and Swedish physicist Bo Thidé claims to have found a way to increase spectrum capacity by twisting radio waves. The “twisting” part stems from the application of orbital angular momentum (OAM), a century-old discovery which states that electromagnetic fields can transport not only energy and linear momentum but also angular momentum, to radio beams. OAM has already been applied to laser optics, but not to RF technology until recently.

What that essentially means is that it’s possible to leverage OAM to twist a radio wave into a vortex, which creates distinctly shaped sub-frequencies that can be used to transmit and receive data without interfering with one another. According to the October issue of Discover, that could mean a 100x bandwidth increase for wireless broadband (although Tamburini says that, in theory, an OAM vortex could generate subfrequencies to infinity).

Tamburini and his team successfully tested the technology [PDF] in the field in Venice this past June, beaming two radio signals from an offshore island to Piazza San Marco a little under 500 meters away.

The next step will be to miniaturize the antenna technology to make it suitable for mobile devices, and also to increase the distance of the signal. The latter may be tricky, according to Science News, as the antennas in the San Marco demonstration had clear line of sight.

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Categories: Other Posts · Telecom Equipment · Wireless