Adaptive matching for compact MIMO systems

Compact MIMO systems using closely spaced antennas are faced with the well-known problem of antenna mutual coupling (MC) that can degrade the performance. Previous studies have shown that a proper choice of antenna load impedances can maximise the MIMO capacity or received power in the presence of MC. However, to calculate this optimum load, prior knowledge of the propagation channel matrix and the MC model, which is difficult to measure practically, are required. In this paper, we present an adaptive matching approach for the receiver that directly deals with the received signals rather than the channel and MC models, to find optimum load impedances which maximise the MIMO capacity or received power.