Capacity of linear rectangular microstrip antenna arrays

In this work, the dependence of the capacity of 2timesM MIMO systems on the mutual coupling between the transmitting and receiving antennas is investigated taking into account the correlation coefficient given by Clarke´s model. Linear arrays of microstrip rectangular antennas are considered both in the transmitting and the receiving ends. The effect of the mutual coupling between microstrip antenna elements on the capacity of the system for several array configurations is studied. Additionally, the impact of non-ideal impedance matching of the antenna elements is investigated. Assuming an infinite array approximation for coupling, it is shown that for element separations more than a half wavelength, coupling has negligible effect on the capacity compared to the uncoupled case. Furthermore, it is shown that the impedance mismatch has a significant effect on capacity. It is also shown that in the case of a 2times2 MIMO system the angle variation of the coupling has a relatively small impact on the capacity.