OAM pseudo-doppler receiving architecture

An orbital angular momentum (OAM) receiver system, comprising:

• at least two receiver antenna elements configured to receive radiated OAM signal beams and generate antenna element output signals based on the received radiated OAM signal beams, the receiver antenna elements positioned tangentially along a circular locus and spatially separated by a distance d;
• the radiated OAM signal beams containing superposed order modes in which each of the order modes is denoted by integer k and a total number of superposed modes is denoted by integer K, wherein each of the K modes encompasses an individual stream of information data symbols;
• the circular locus having a radius R corresponding to a footprint area of the received radiated OAM signal beams, wherein the circular locus contains a characteristic phase gradient pertaining to each OAM beam along a circumference of the circular locus;
• and
• a variable ratio combining unit operative to receive and combine the antenna element output signals in time-varying proportions, the variable ratio combining unit configured to:
• switch between portions of the antenna element output signals in accordance with a high-rate periodic waveform of frequency F, the high-rate switch operation providing emulation of unidirectional movement by a virtual receiver antenna element along the circumference of the circular locus to produce a pseudo-Doppler frequency shift;
• modulate and time-gate the antenna element output signals in accordance with the high-rate periodic waveform to impart a fractional pseudo-Doppler shift to each OAM mode;
• and
• combine the modulated and time-gated antenna element output signals in accordance with the fractional pseudo-Doppler shift to facilitate separation of the OAM modes encompassing streams of information data symbols.