Systematic Design Method for Asymmetric Multiport Antennas Based on Characteristic Modes

A systematic design procedure for placing ports with low correlation on an asymmetric antenna geometry is presented. By applying the mathematical description of symmetry based on group theory and group representations to the theory of characteristic modes, it is shown that it is in general not possible to realize uncorrelated antenna ports on an asymmetric antenna. Therefore, a port placement procedure based on characteristic modes is proposed for such geometries in order to realize ports with low correlation. The design procedure is based on modal parameters alone. Thus, only one full simulation run is needed in order to perform the modal analysis. The proposed procedure is illustrated by means of numerical examples.