Effect of Element Mutual Coupling on the Capacity of Fixed Length Linear Arrays

The effect of element mutual coupling on the capacity of multiple-input-multiple-output (MIMO) antenna systems is demonstrated by considering a fixed-length linear array of half-wave dipoles. Mutual coupling between elements, which influences both the spatial correlation and the received signal-to-noise ratio (SNR), is taken into account by means of the impedance matrix. Monte Carlo simulations are performed for both single-sided (i.e., transmitting end or receiving end) and double-sided fading correlations. It is shown that mutual coupling results in substantially lower capacity and, hence, in reduced degrees of freedom.