4.8-Gbit/s broadband wireless communication link at radio frequency using orbital angular momentum and polarisation multiplexing

Recently, the ability of orbital angular momentum (OAM) of electromagnetic fields at radio frequency to multiplex multiple beams has been investigated. Such OAM multiplexing can be used to increase channel capacity and spectral efficiency. However, the studies of OAM multiplexing are restricted to narrow band. In this Letter, the authors experimentally demonstrate a 4.8-Gbit/s broadband OAM and polarisation multiplexing wireless link in which the operating frequency is from 2.1 to 2.7 GHz, with a relative bandwidth about 25%. The proposed wireless communication link over 2.5 m achieves a spectral efficiency of similar to 8 bit/s/Hz by using two independent OAM beams for each of two polarisations. All four independent OAM channels propagate along the same beam axis with crosstalk less than -13.3 dB from 2.1 to 2.7 GHz. All four channel signals are recovered with a bit error rate of 3.5 x 10(-3) when the signal-to-noise ratio is 24 dB.