On the MIMO capacity using a Butler matrix with circular arrays in fading indoor environments

This paper presents the benefits of using a Butler matrix network with circular arrays of closely located antennas in different scenarios of a fading indoor MIMO environment. We describe the design conditions for the multi element antenna (MEA) structure required to take full advantage of a MIMO scheme from the antenna point of view. Simulations on the system capacity have been carried out using a two-ring MIMO model for indoor cells and including the coupling between the antennas.