1 Bit Non-Diffractive Vortex Beam Generator Based on FSS in Microwave Region

In this article, a low-profile planar 1 bit non-diffractive vortex beam generator is proposed based on frequency selective surface (FSS) in microwave region. The characteristic of Bessel beam is introduced to control the divergence of the vortex beam. The proposed unit cell is analyzed through equivalent circuit model. The main resonance is provided by the coupling between the patches and the circular slot grid. A cross patch is embedded in the slot to form another resonance. Two elements with 0° and 180° transmission phase are designed to discretize the phase distribution of the metalens. The simulation results show that the metalens can generate fulfill non-diffracting transmission upon a distance of the 32λ
₀
, verifying the effectiveness of the proposed method.