In this paper we analyze a MIMO array consisting of two circular microstrip antennas, designed to exploit pattern diversity. We analytically derive the spatial correlation coefficients of this array as a function of the mode excited for realistic clustered MIMO channel models. We compare the performance of the circular patch array (CPA) against an array of two spaced dipoles. In particular, we compute a theoretical tradeoff to predict when the pattern diversity provided by the CPA is more effective than space diversity from the ULA, based on the eigenvalues of the spatial correlation matrix. Through simulations we show that CPAs yield better performance or satisfy more restrictive size constraints than uniform linear arrays (ULAs) in clustered MIMO channels, depending on the element spacing of the ULA. These results make the CPA an attractive solution for minaturized MIMO arrays for portable devices or access points.

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