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Scientists Twist Radio Beams To Send Data At 32 Gigabits Per Second
concertina226 writes Scientists from three international universities have succeeded in twisting radio beams in order to transfer data at the speed of 32 gigabits per second, which is 30 times faster than 4G LTE wireless technology in use today. The researchers, led by Alan Willner, an electrical engineering professor with the University of Southern California Viterbi School of Engineering, successfully demonstrated data transmission rates of 32 gigabits per second across 2.5m of free space in a basement laboratory.
Read the research. 19dB.
http://www.nature.com/ncomms/2014/140916/ncomms5876/full/ncomms5876.html
Along with IR and Visible light, unless you are pumping watts into a very small volume you're not going to boil your guts with wifi.
Dear aunt, let's set so double the killer delete select all
Frankly, I am still confused as to why it's not (more simply) "circular polarisation" that has been known about since the early days of radio.
Since you linked to Wikipedia, I'm going to assume that Wikipedia didn't do a very good job at explaining the difference. While OAM and circular polarisation both describe some sort of spinning, they correspond to different phenomena. As you may know, electromagnetic waves are oscillations of the electric (and magnetic) field, with the field at each spatial position varying over time. You may also recall from your high school physics class that the electric field at any position is a vector quantity --- it has both a strength and a direction. The polarisation of a electromagnetic field is a description of the direction that the electric field points, and circular polarisation can be roughly seen as the electric field direction rotating as you travel in the direction of propagation. What OAM is describing is the phase relationship between the oscillations of the field at different positions (whether the oscillation at one point is lagged or ahead compared to a different point); it can be roughly thought of as a spinning motion in the transfer of energy inside an electromagnetic field.
For a rather inaccurate, but perhaps intuitive, analogy, try imagining a giant stream of asteroids coming your way in outer space. If the rocks are following a spiral trajectory as they come at you, then this corresponds to the rocks having "orbital angular momentum". If the rocks are themselves spinning, then this corresponds the rocks being "circularly polarised".
This is a myth. There is nothing special about 2.4 GHz as far as water is concerned. There is a mild absorption peak at 24 GHz, but nothing at 2.4.
As a microwave engineer, I find it unfortunate that it is called "orbital angular momentum" or "twisted beams". It causes confusion for many in the antenna engineering community. It is _not_ circular polarisation, but a form of spatial diversity non unlike MIMO systems. Where it differs from MIMO is, instead of translational spatial diversity, we have angular spatial diversity. The "beams'" phase fronts "twist" at different rates (there is no "twisting" of the direction of the E-field vector, as is the case with circular polarisation). This provides a means to multiplex many signals on the same "beam". Incidentally, you can also exploit polarization on top of the angular spatial diversity to (nearly) double the transmission capacity.