High data rate wireless transmission in the non-far zone with 2D orthogonal beams

A high data rate transmission system for short range application is proposed. The system is composed of two identical flat rectangular antennas separated by a distance in the non-far zone. Each antenna generates four two-dimensional orthogonal beams by a passive and low-loss beam-forming network. Thanks to the orthogonality relation between the beams, several channels with the same frequency and in the same direction could be carried and the signal demultiplexing is facilitated in the reception side. Wireless transmission using two-dimensional orthogonality of the aperture field distribution in the rectangular coordinate system is achieved, which is equivalent to Orbital Angular Momentum (OAM) transmission using two-dimensional orthogonality in the cylindrical coordinate system. To validate the proposed concept a transmission system has been designed, fabricated and tested in the E-band around 78.5 GHz. The system generates 4 orthogonal beams and compared to a Single Input Single Output (SISO) system the spectral efficiency could be enhanced up to fourfold.