Channels distinguished by vorticity experience crosstalk in the presence of plane scatterers like buildings, the ground, the sky... It seems pretty well restricted to what they used - a parabolic mirror, aiming it along a direct line of sight to the receiver.
This could potentially be very useful for communications in space, where we can't spatially resolve a large number of faraway receivers. You can address by vorticity instead of frequency, and each receiver gets a full spectrum of bandwidth.
I could be off on this, but in short, it looks legit, if specialized.
~~ edited to add ~~
This doesn't technically increase the number of channels available. What it does make possible is distinguishing these channels without having to have lots of antennas cooperating on sending every signal. One antenna, one channel.
Encoding many channels on the same frequency through radio vorticity: first experimental test
"We have shown experimentally, in a real-world setting, that it is possible to use two beams of incoherent radio waves, transmitted on the same frequency but encoded in two different orbital angular momentum states, to simultaneously transmit two independent radio channels. This novel radio technique allows the implementation of, in principle, an infinite number of channels in a given, fixed bandwidth, even without using polarization, multiport or dense coding techniques. This paves the way for innovative techniques in radio science and entirely new paradigms in radio communication protocols that might offer a solution to the problem of radio-band congestion."
"Moreover, our experimental findings demonstrate that the spatial phase signature was preserved even in the far-field region and for incoherent non-monochromatic wave beams. These results open up new perspectives not only for wireless communication but also for physics and astronomy, including the possible detection of Kerr black holes in the test general relativity"
This looks too good to be true, but I cannot see any obvious issues, and they have an experimental confirmation.
If this pans out, it would be a black swan in the making for many of the wireless spectrum allocation/licensing authorities and companies.