Diversity Efficiency of Multimode Antennas Impacted by Finite Pattern Correlation and Branch Power Imbalances

With the requirement to support high data rates for multimedia-driven applications in wireless communications, multiple antenna techniques have to be considered even at the mobile device. As a result of headroom restrictions predominantly multimode antenna configurations can be used that provide radiation patterns with independent polarization and shape. Compared to antenna configurations with spatially decorrelated elements, size requirements of multimode operating antennas can be reduced substantially. This investigation deals with an analysis of the hypothetical bounds of systems reliability improvement by using multimode antennas for diversity combining at the mobile device. In order to separately evaluate the influence of branch correlation and branch power imbalances on the diversity efficiency, suitable normalization procedures are introduced.