Proximity effects on diversity antennas

Proximity effects constitute a threat to the performance of a diversity antenna when it is operating under physically constricted, limited-area conditions which are typical of indoor environments. Two factors contribute to the degradation of the antenna performance: the reduction of the branch mean signal-to-noise ratios and the increase of the branch signal correlation. The overall loss of diversity gain can be evaluated from these factors. Theoretical investigations of a two-element space diversity antenna mounted on an infinite ground plane and an infinite corner reflector show that proximity effects (i.e. proximity to the ground plane or reflector) can result in a significant loss of diversity gain. The severity of the proximity effects depends an the spacing between the two elements, and on the location and orientation of the pair of elements