Correlation characteristics of diversity antennas in mobile environments

The performance of a diversity system is evaluated by both the antenna gain and diversity gain. Good diversity gain is generally obtained for antenna diversity systems with minimized cross correlation and coupling effects. Therefore, this paper introduces numerical and graphical algorithms to estimate the envelope correlation coefficient (rho_e), and hence the parameters for optimum antenna diversity configuration are derived. The proposed procedure is based on numerical calculations of relevant derived formula for rho_e in terms of the propagation environment and the antenna pattern. A more convenient way is presented to estimate rho_e from the scattering parameters, and the normalized mutual resistance R₁₂ between diversity antenna ports. Moreover, different co-polar, and cross-polar antenna pattern cuts in principal planes, are used to evaluate and analyze the correlation characteristics. The developed algorithms are then applied to investigate the performance of spatial diversity antenna systems.