Effect of antenna directivity on the channel capacity of MIMO systems

The effect of antenna directivity on both spatial fading correlation and signal-to-noise ratio based on Kronecker channel model is investigated in three dimensional scattering environments. The channel capacity of multiple-in multiple-out system for uniform circular array, line array, and rectangle array is studied. The contribution of antenna directivity to channel capacity is concluded that, when the main lobe of directive antenna points at the coming wave, the improved signal to noise ratio (SNR) resulting from the antenna directivity will exceed the negative impact caused by increased spatial fading correlation, leading to a better channel capacity than that of isotropic antenna. The stronger antenna directivity is, the greater the channel capacity.