Analysis of orbital angular momentum electromagnetic wave propagation based on circular antenna array

Orbital angular momentum (OAM) electromagnetic vortex technology is a kind of advantageous communication reuse technology with high spectral efficiency. This paper presents a novel circular antenna array for microwave relay communication, which is the transceiver hardware foundation of OAM electromagnetic wave. The antenna array is composed of horn antennas operating at E-Band, which has good polarization purity to effectively confront polarization fading in wireless channel. The electromagnetic waves with dual characteristics of circular polarization and multi-modal vortex OAM is generated with the optimization design of antenna forms and distance between the elements. In order to avoid the degradation of OAM mode transmission in the free space, the number of antenna elements and relation between transmission distance of electromagnetic vortex wave and antenna array form are discussed. A reasonable OAM antenna aperture is obtained based on the simulation of electromagnetic waves propagation. The stable convergence of gain pattern and phase distribution proves the circular antenna array could be applied to OAM relay communication by combining with advanced weights optimization method.