Metasurface Design for Wideband and High-Efficiency Polarization Conversion Applications

Abstract

The domain of chiral metasurfaces is of greatest interest among scientific community. They are being applied to manipulate and control the fundamental parameters of Electromagnetic waves (EM) waves. Manipulation of EM waves have numerous applications including flat lensing, beam splitting, radar cross section reduction, antennas gain enhancement, real-time holograms and polarization conversion. These metasurfaces are effectively replacing the conventional methods like Faraday’s effect and using crystalline chiral molecules especially for polarization control. Metasurfaces are being designed to achieve polarization manipulation through compact design having a wide bandwidth and angular stability. In this thesis, an L-shaped anisotropic chiral metasurface is designed to obtain a linear to circular polarization at two distinct bands, 4.5 GHz and 5.5 GHz, in transmission mode at microwave frequencies. The design is optimized by parametric studies. Moreover, the proposed metasurface has a stable response under oblique incidence angles up to 30o . Apart from being efficient, the chirality and anisotropic design of the structure offers a higher fractional bandwidth compared to the existing metasurfaces having functionality of linear to circular polarization conversion. Fractional bandwidth of proposed metasurface is 8.9% and 7.5% at 4.5 GHz and 5.5 GHz respectively. Also, the fabrication complexity is reduced. The compact size, angularly stable, higher fractional bandwidth and easy fabrication makes it a good candidate for the applications in C band.