A Broadband Transmissive Linear-to-Circular Polarization Converter Based on Metasurfaces

Polarization control technology is widely used in communication systems by using polarization converters. In this paper, a novel line-to-circular polarization conversion (LCPC) based on transmission metasurface is proposed, which can convert the incoming linear polarization wave into circular polarization wave in X band. To obtain broad bandwidth, the unit cell is composed of three metal layers, and the upper and bottom metal layers are connected by a metal column, which can thus provide anisotropy to obtain two orthogonal electric field vectors with the same amplitude and 90-degree phase difference in the required frequency band. The middle layer is a hexagonal metal ring in order to broaden the bandwidth further. The simulated results show that the axial ratio (AR) bandwidth is 8.92~12.22GHz (31.2%). Under normal incidence when the totally transmittance is greater than -2dB. And the performances of the proposed metasurface can remain stable when the incident angle ranges from -30° to +30°. In a word, the designed metasurface has the advantages of broad bandwidth and stability to incident angles.