An outstanding display of a means to boost the information-carrying
capability of radio waves has taken place across the lagoon in Venice,
Italy. The key lies in the distinction between the orbital and spin
angular momentum of electromagnetic waves. According to Prof Thide It's
exactly the same place that Galileo first demonstrated his telescope to
the authorities in Venice, 400 years ago.
An ideal analogy is the Earth-Sun scheme. The Earth spins on its axis,
manifesting spin angular momentum at the same time orbits the Sun,
manifesting orbital angular momentum. In the simplest case, putting a
twist on the waves is as easy as putting a twist into the dish that
sends the signal. The team split one side of a typical satellite-type
dish and separated the two resulting ends.
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