Performance of MIMO systems employing multiple compact patch antennas with radiation pattern diversity

The purpose of this work is to study the performance of Multiple-Input Multiple-Output (MIMO) systems that use multi-mode antenna as basic elements. The design is focused to be a compact model, suitable for being used in relatively small terminals. Given the small size of the designs, the idea is not to substitute the use multiple antennas for one element with multiple modes but to combine multiple compact multi-mode antennas. To this aim, the design of two small multi-mode patch antennas is presented as well as a study of channel spectral efficiency. Spectral efficiency is computed comparing several multi-element-multimode antennas scenarios to alternative scenarios with single-mode antennas. For spectral efficiency studies it is necessary to model the MIMO channel taking into account that multiple-element-multiple-mode antennas will be used. The proposed model relies on a small set of parameters that fully characterizes spatial and modal correlation in terms of the antenna geometry, the radiation patterns and the angular spread in the channel.