Bidirectional matching technique for Tx and Rx ports in short-range MIMO

This paper proposes a bidirectional matching technique for Tx and Rx ports in a short-range MIMO system. First, by connecting 180-degree hybrid couplers to a plane-symmetrically configured MIMO system, both Tx and Rx ports are decoupled, and channels between them are orthogonalized, that is, the MIMO system is converted into multi orthogonalized SISO systems. Next, matching is done at both Tx and Rx ports of each SISO system based on the theory of conjugate-image impedance. As a result, the transmission power of the short-range MIMO is maximized. Numerical results show that the proposed technique realizes the higher channel capacity than that of conventional eigenbeam-space division multiplexing.