Mode Purity Improvement of High‐Order Vortex Waves

Vortex electromagnetic waves can carry orbital angular momentum (OAM) modes of different order number, which are mutually orthogonal. Communication technologies multiplexing OAM topological charges have attracted extensive attention in improving spectrum utilization. In this regard, the efficient generation becomes a key issue. However, it is difficult to generate high-order by using microstrip antenna with simple structure, and mode purity usually not high. Methodologically, wave mostly achieved synthesizing degenerate eigenmodes. paper, combined eigenmode analysis, construction high-purity antennas carried out from perspectives radiating element, ground plane, structural symmetry. For regular hexagonal patch 4th-order mode, improved about 40% over 80% removing inner conductor layer, circular adding lug patches on outside. This method through analysis significance characteristic current distribution also has guiding for design other antennas.