A group of Italian and Swedish researchers appears to have solved the problem of radio congestion¹（拥挤） by cleverly twisting radio waves into the shape of fusilli（意大利螺旋面） pasta, allowing a potentially infinite number of channels to be broadcast and received. Furthermore, the researchers have demonstrated this in real-life conditions by beaming two twisted radio waves across the waters of Venice.

Their results have been reported on March 2, in the Institute of Physics and German Physical Society's New Journal of Physics.

As the world continues to adapt in the digital age, the introduction of new mobile smartphones, wireless² internet and digital TVs means the number of radio frequency bands available to broadcast information gets smaller and smaller.

"You just have to try sending a text message at midnight on New Year's Eve to realise how congested the bands are," said lead author Dr Fabrizio Tamburini. The researchers, from the University of Padova, Italy, and the Angstrom Laboratory, Sweden, devised a solution to this by manipulating waves so that they can hold more than one channel of information.

A wave can twist about its axis³ a certain number of times in either a clockwise or anti-clockwise direction, meaning there are several configurations⁴ that it can adopt.

"In a three-dimensional perspective, this phase twist looks like a fusillli-pasta-shaped beam. Each of these twisted beams can be independently generated, propagated and detected even in the very same frequency band, behaving as independent communication channels," Tamburini continued.

To demonstrate this, the researchers transmitted two twisted radio waves, in the 2.4 GHz band, over a distance of 442 metres from a lighthouse on San Georgio Island to a satellite dish on a balcony of Palazzo Ducale on the mainland of Venice, where it was able to pick up the two separate channels.

"Within reasonable economic boundaries, one can think about using five orbital angular momentum⁵ states, from -5 (counter-clockwise) up to 5 (clockwise), including untwisted waves. In this instance, we can have 11 channels in one frequency band.

"It is possible to use multiplexing（多路发讯） , like in digital TV, on each of these to implement⁶ even more channels on the same states, which means one could obtain 55 channels in the same frequency band," said Tamburini.

In addition to increasing the quantity of information being passed around our planet, this new discovery could also help lend an insight into objects far out in our galaxy⁷. Black holes, for example, are constantly rotating and as waves pass them, they are forced to twist in line with the black hole.

According to Tamburini, analysing the incoming waves from the supermassive black hole at the centre of the Milky⁸ Way, Sagittarius A, could help astronomers⁹ obtain crucial information about the rotation¹⁰ of this "million-solar mass monster."