Experimental Demonstration of the Capacity Gain of Plane Spiral OAM-Based MIMO System

A plane spiral orbital angular momentum (OAM) waves-based 4 × 4 multiple-in-multiple-out (MIMO) communication system for line-of-sight channel is proposed and experimentally demonstrated in comparison with conventional MIMO. The transmitting OAM waves are propagating along the transverse direction; hence there is no singularity or divergence problem. Compared with the conventional MIMO, this system could achieve lower spatial correlations and a higher capacity gain while the OAM antennas as the elements of the transmitting array are sorted in an ordered sequence. The measured bit-error-rate performance clearly demonstrates the feasibility of the proposed system, and the causation of the improved performance is also detailedly discussed. This technology can be applied in near-field communications or short-range MIMO systems to realize higher capacity communications.