Performance of compact antenna arrays with receive selection

The objective of this paper is to evaluate the performance of dual-polarized Multiple-Input Multiple-Output (MIMO) systems, compact in antenna array size and with reduced radio frequency complexity. We compare co-located antenna array structures with their spatial counterpart while deploying receive antenna selection. To this purpose, the performance in terms of MIMO maximum mutual information is presented. A simple norm based on instantaneous channels selects the best antennas. We derive explicit numerical expressions for the effective channel gains. These expressions are precise for small values of N_S and N_R, and approximately valid for higher values of N_S and N_R, N_S and N_R being the number of selected and total receive antennas, respectively. Further a comparison in terms of power imbalance between antenna elements is presented. We conclude that angularly separated compact antenna arrays with a few simple monopoles, if used with antenna selection can provide a better performance compared to a conventional Uniform Linear Array (ULA). We also show that co-located structures are robust to power imbalance and orientation variations compared to a ULA.