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. Such a 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). Typically, the MDN input ports require matching networks to achieve proper antenna operation. The objective of the proposed design approach is to overcome the need of such matching networks therefore enabling wider operating bandwidths. This approach is then used to design a four-element MIMO antenna capable to achieve polarization and pattern diversity by means of four radiation patterns directed along a hemisphere. Simulation results of the antenna show that very low envelope correlation coefficients (ECC) and good mean effective gains (MEG) can be achieved. These features along with full port decoupling make the proposed antenna design very attractive for base station applications of next generation.