Equivalent Relations Between Interchannel Coupling and Antenna Polarization Coupling in Polarization Diversity Systems

Both the interchannel coupling (CC) among multiple compact circuitry channels and the antenna polarization coupling (APC) due to angular deviation of antennas (ADA) in diversity systems cannot be neglected in practice. The effects of these two problems are considered in this paper. The investigation of the CC in a two-branch orthogonal polarization antenna diversity system is extended to the case of a general multibranch polarization antenna diversity system, and the CC is investigated together with APC by applying a network theory framework. Their effects on both the correlation and the mean power ratio among received signals are obtained. It is found that the effects of both kinds of couplings as well as that of the combining signal processing on the received signals can be considered as a series of weightings. Two equivalent relations among APC, CC, and ADA are developed. Such equivalences reveal insights into CC from the point of view of antennas and provide additional degree-of-freedom for system optimization to improve the diversity performance. Furthermore, two kinds of compensation techniques are also developed to mitigate the APC and CC, as well as to enhance the diversity performance. Finally, some numerical results are presented to validate the analyses.