Evaluation of OAM Mode Multiplexing Considering Ground Reflection

Orbital angular momentum (OAM) is a physical quantity of an electromagnetic wave which is independent of polarization, and the electromagnetic wave having the OAM becomes a helical wave. A mode of the OAM can be defined according to the number of turns of helix per wavelength distance, and the different modes are mutually orthogonal. In recent years, with growth of the millimeter wave technology and demands for further high-speed large capacity transmission, a new spatial multiplexing transmission scheme using the orthogonality of OAM has attracted attention. In this paper, the impact of the ground reflected wave were evaluated by comparing the characteristics of OAM mode multiplexing and eigenbeam-space division multiplexing. As a result, it is found that the inter-mode interference due to the ground reflected wave is not so large and can be reduced with a small amount of degradation.