Dual-frequency broadband metasurface for independently generating multiple vortex beams based on spin decoupling

A dual-frequency broadband metasurface capable of generating four circularly polarized vortex beams with independent control of the topological charge and deflection direction is proposed. The broadband unit-based top and bottom layers of the designed metasurface generate the vortex beams in the Ku band (10–20 GHz) and the Ka band (26–30 GHz), respectively. A custom-designed frequency selection surface is inserted to minimize the mutual interference. The far-field measurement experimental results confirm that the designed metasurface generates four vortex beams with the deflection directions of θ _L = -40°, θ _R = 20°, and θ _L = -40° and θ _R = 30°across the broad bandwidth in the Ku and Ka band, respectively.