Triple-band ultra-thin linear to circular polarization converter based on transmission metasurface

In this article, a triple-band linear-to-circular transmissive polarization converter based on metasurface is proposed, which can transform a linearly polarized incident wave into right-hand circularly polarized wave and left-hand circularly polarized wave in three nonadjacent frequency bands. Since the proposed polarization converter has a novel structure with only one metallic layer, the proposed converter is ultra-thin. After simulating, the results demonstrate that the axial ratio of the proposed transmissive circularly converter is below 3-dB in 7.3-10.4 GHz, 11.9-18.7 GHz and 21.6-29.6 GHz. Additionally, the physical mechanism of multiple resonances is discussed based on equivalent circuit model. Moreover, a prototype is fabricated and measured; the experimental and simulation results are in good agreement. This polarization converter can be employed to manipulate the polarization state of signals in microwave communication.