Mode-Based MIMO Antenna with Polarization and Pattern Diversity for Base Station Applications

This paper introduces a new design approach for multi-element MIMO antennas that exploit the mode-based technique and proposes a novel antenna structure capable of achieving polarization and pattern diversity. The mode-based technique applied to a multi-element antenna with circular symmetry allows to obtain orthogonal radiation patterns and full port decoupling by means of a mode decomposition network (MDN). Generally, to achieve proper antenna functioning the MDN input ports require matching networks which can limit the operating bandwidth. The objective of the proposed design approach is to overcome the need of such matching networks. This approach is then used to design a four-element MIMO antenna featuring four directional radiation patterns operating within a common bandwidth. The simulation of envelope correlation coefficient (ECC) and mean effective gain (MEG) of these radiation patterns confirm their orthogonality and efficient operation. These features along with full port decoupling make the proposed MIMO antenna attractive for next generation base station applications.