Factorization of the antenna correlation coefficient for improved performance assessment

The correlation coefficient between the received signals from a pair of antennas is a parameter which provides information about the performance of an antenna pair in diversity and MIMO applications. In case the correlation coefficient is low, a deeper assessment of the antenna performance can be made by investigating the cause for the low correlation coefficient. A separation of the correlation coefficient into two factors is proposed. The factors reveal to what degree it is amplitude variations (complementary coverage) or phase difference variations over the sphere that is the cause. Expressions for the proposed factors are presented, and examples are given in which the proposed factorization is motivated.