An Ultra-thin Wideband Linear to Circular Polarization Converter using Metasurface

In this article, an ultra-thin (similar to lambda/12) metasurface is designed to convert an incident linearly polarized wave to the reflected circularly polarized wave over wider bandwidth. The reflective type metasurface structure is realized using two opposite facing quarter rings structure printed on grounded FR4 substrate. Circular polarization conversion for the proposed structure is realized over frequency range 9.97 GHz to 15.93 GHz with an enhanced fractional bandwidth of 46% for ellipticity greater than 0.90. The structure is also studied for oblique incidences for which it maintains axial ratio within 3 dB upto 45 degrees incident angles. Further, the reflected wave is converted into the cross polarized wave at three distinct frequency bands.