MIMO System Sensitivity and Coupled Array Design

Recent theoretical and simulation studies reveal that closely coupled antennas with appropriately chosen impedance matching loads can yield desirable MIMO capacity. The performance sensitivity of a 2 x 2 MIMO system with coupled half- wavelength dipoles and single-port decoupling matching networks is presented in this paper. We show that the optimal single-port matching impedance in the sense of maximizing capacity exists for various small antenna spacings. It is a promising approach to improve the compact array performance. The sensitivities of MIMO capacity with matching networks to antenna spacing and antenna structures are also discussed.