Generation of a Square Multi-Mode Multi-Port Aperture Antenna by Selective Modal Excitation

A methodology for the generation of a multi-mode multi-port aperture antenna is proposed based on the selective excitation of magnetic current modes. The magnetic current modes are determined based on the analytical solution of waveg-uide modes with the same aperture dimensions. An excitation technique for the modal magnetic aperture currents is shown by placing multiple ports within the aperture. Guidelines for the port placement within the aperture are given based on the magnetic current distribution. Further, a feeding network topology is proposed to selectively excite the magnetic current modes of the aperture. The theory is evaluated and validated by an analysis of the radiation patterns of the individual antenna ports as well as an investigation of the envelope correlation coefficient of the radiation patterns. It is shown that the excited far- fields are orthogonal, which confirms the claimed selective excitation of the magnetic current modes.