Coupling effects on richness threshold of multi-port antennas in multipath environments

This paper investigates convergence in diversity gain of multi-port antennas in non-rich multipath environments. It is shown that diversity gain convergence is faster in the presence of strong coupling. In this situation, richness threshold is also smaller. Furthermore, by linking convergence in diversity gain to convergence in antenna ports' correlations, the role of pattern diversity caused by coupling is highlighted. A range of variation for correlations is defined whose upper bound is used to quantify pattern diversity. The lower bound for this range is the corresponding spatial correlation in a rich multipath environment.