On impedance matching and bandwidth of compact antenna arrays

In English We analyze the impact of the matching network on compact MIMO systems. Existing studies have found that the matching network has a significant influence on the performance of multiple antenna systems when the antennas
are in close proximity. However, none has examined the wideband case. In this paper, we investigate the wideband performance of four different matching networks for multiple dipole antennas. The performance of the matching networks is given in terms of the bandwidths of correlation and matching efficiency, which are extensions of the single-antenna concept of
bandwidth to multiple antenna systems. For a uniform 2D angular power spectrum, we find that while individual-port matching can achieve a large correlation bandwidth for envelope correlation of 0.5 at a small antenna separation of 0.01l, multiport matching is required for efficiency bandwidth to be defined for a return loss of −6dB. Moreover, even with
multiport matching, both correlation and efficiency bandwidths decrease drastically at small antenna separations.