Abstract: A useful model for analyzing mutual coupling (MC) of the X-type polarization diversity system is put forward. The effects of MC in both antennas and circuits on the performance of the system are investigated. The expression for the correlation coefficient for the polarization diversity system is obtained. Therefore the effects of MC on the signal correlation coefficient, mean power ratio and system polarization diversity gain can be investigated more comprehensively. It is concluded that MC could raise correlation but also decrease the mean power difference, thus improving the diversity gain. In addition, the dominant effects of Cross Polarization Discrimination (XPD) on the signal correlation coefficient and mean power ratio of system are illustrated. It is shown that the larger the XPD, the lower the polarization diversity gain will be.

Key words: multi input multi output, polarization diversity, mutual coupling analysis, correlation coefficient, polarization diversity gain