Mutual coupling effect in multiantenna wireless communication systems

A thorough investigation of mutual coupling effect on wireless communication systems is presented. Multiple antennas utilized by adaptive antenna arrays, spatial diversity structures, and multiple input-multiple output (MIMO) systems are analyzed for this purpose. In adaptive antenna arrays, mutual coupling can deteriorate the algorithms for getting the direction of arrival (DOA) and beamforming structure. In spatial diversity and MIMO systems, mutual coupling can increase or decrease the correlation between individual subchannels depending on the antenna configurations and the environment. An extensive mutual coupling model is needed to better analyze its effect on these systems. Available models either do not reflect all the parameters affecting mutual coupling or are not separable to the individual terms for a better analysis. In this paper, it is shown that mutual coupling can be expressed in terms of individual couplings due to antenna array geometry, near-field scatterers (NFS), and DOA. For MIMO and spatial diversity, DOA dependency drops since the feeding network does not have to be changed for a given DOA. By including the effect of NFS into the mutual coupling expression, the effect of mutual coupling on wireless communication systems can be better studied.