In this paper we analyze a multiple input multiple output (MIMO) array consisting of two circular microstrip antennas, designed to exploit pattern diversity. The two circular microstrip elements are collocated and stacked upon each other. The spatial correlation coefficients of this array as a function of the mode excited, for realistic clustered MIMO channel models are derived. The angle of arrival/angle of departure are distributed only over the azimuth direction is the assumption taken for circular patch array (CPA) and the performance is compared against an array of two spaced dipoles with the help of the simulation results. Simulation tool used is MATLAB 7.4.