A polarization conversion metasurface for broadband and high-efficiency bidirectional filtering

Abstract

Here, we demonstrate a polarization conversion metasurface which is composed of a single layer square split-ring resonator and bi-layered slotted perfect electrical conductor (PEC) to realize broadband and high-efficiency bidirectional filtering. The numerical results indicate that y-polarized waves can be converted to x-polarized transmission waves in the frequency range of 6.6 GHz to 13.9 GHz, while prevent this polarized waves with frequency beyond this band, and purity x-polarized waves can be obtained as electromagnetic (EM) waves are incident along negative z-axis, meanwhile, x-polarized waves can be converted to y-polarized transmission waves and only y-polarized waves available when EM waves are incident along positive z-axis. This designed polarization conversion metasurface has the function of bidirectional filtering in a wideband frequency range. Furthermore, the broadband property can be maintained as the incident angle up to 30°. The Fabry–Pérot-like cavity model is established to clarify the interference and enhancement effect of polarization conversion, and the electrical field and surface current distributions are used to elucidate the physical mechanism of polarization conversion and filtering. The experimental results are coincident with the numerical simulations. This metasurface can be employed in controlling the filtering signal of the polarized devices and can be functional as a bandpass filter in communication systems.