Thank you for sending this, Colin! At first I thought that this was some kind of hoax but I read further and learned something very valuable. It turns out there are additional options for differentiating between radio beams besides frequency and polarization. It turns out that there are solutions to Maxwell's equations which allow light to "spin" about an axis which are not the traditional circular polarization. This was only discovered in the 1970s and apparently not well understood until 1992. The guys that Colin mentions demonstrated that these effects can be used to transmit multiple radio beams to the same receiver and that these beams can carry distinct information. More importantly, there is the theoretical possibility to have an infinite number of such beams, unlike traditional elliptical polarization (circular plus linear) which only allows two orthogonal beams at the same point. I suppose one could also simply send multiple "pencil" beams to several receivers close to each other and achieve the same thing, but I think that the "new" method does not require such ultra-directive antennas. For more explanation of the basic physics, see: people.physics.illinois.edu/Selvin/PRS/498IBR/Twist.pdf It made me feel a bit better when this article stated that most physicists do not know this :) I was certainly surprised! Sean On Sat, Mar 3, 2012 at 8:03 PM, cdb wrote: > The ability to send two different radio frequencies in a helical construc= t > allows a greater concentration of signals within a band. > > I think the research was performed by the Swedish Space Institute, but th= e > link to them is dead. > > =A0 fer-infinite-Wifi-capacity.html> > > Colin > > > cdb, =A0 3/07/2009 > > -- > > > > > colin@btech-online.co.uk > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .