Simultaneous Decoupling and Decorrelation Scheme of MIMO Arrays

Correlations and mutual couplings in antenna arrays lead to performance deterioration of multiple-input-multiple-output (MIMO) systems. The relation between mutual coupling and correlation is complex, especially in non-isotropic multipath environments. Reducing mutual coupling does not guarantee an eventual reduction of the overall correlation and vice versa. In general, it is not a trivial task to reduce mutual coupling and correlation simultaneously in arbitrary multipath environments. In this correspondence, a planar metamaterial structure (PMS) and an array-antenna decoupling surface (ADS) are applied to the antenna array for simultaneous reductions of correlations and mutual couplings. The PMS comprises regularly arranged metamaterial elements holding certain transmission features. The ADS placed between the PMS and array is a substrate with printed rectangular metal strips. A 1 × 4 patch array is taken as an example to demonstrate the effectiveness of the proposed scheme. According to the simulated and measured results, the combination of PMS and ADS can work together without interfering or affecting the matching condition of the antennas. As a result, the mutual coupling and overall correlation between the antenna elements are reduced in a general multipath environment.