Systematic Design of Multimode Antennas for MIMO Applications by Leveraging Symmetry

A systematic procedure for constructing orthogonal antenna ports on arbitrary symmetric multimode antennas is proposed. The procedure is based on the projection operator method from group theory. With this method, optimal orthogonal port configurations are generated analytically. Electromagnetic simulations, modal analyses, or optimization techniques are not required. The optimal port configurations are solely governed by the symmetry of an antenna and can thus be considered asa prioriknowledge. Accordingly, this knowledge is available right from the beginning of the design process and can be purposefully used to compare different suitable antenna geometries with respect to the practical implementation effort. The procedure is illustrated by means of an application example resulting in a complete prototype of a six-port multimode antenna.