A novel bifunctional metasurface based on independent control of transmission and reflection amplitudes and phases

A novel bifunctional metasurface (MS) operating at two frequencies is proposed to manipulate reflected and transmitted waves independently. The element is composed of a slot sandwiched by two C-shape spilt rings (CSRRs). The middle layer is the metal sheet etched the slots, and it is used to select polarization mode of reflection and transmission. Also, it isolates the reflection and transmission elements and eliminates the coupling between them. Therefore, the reflection or transmission amplitude and phase of the proposed MS can be regulated by the corresponding single metal layer compared with the current bifunctional elements. This is helpful to shorten design time. Also, a higher transmission amplitude is achieved with fewer substrate layers and lower profile. The reflection and transmission mode operate at 17.6 GHz and 12.6 GHz, respectively. As a proof of concept, a full-space multibeam generator is validated both numerically and experimentally and a full-space bifocal metalens is demonstrated numerically. The proposed MS provides a new kind of low cost, lightweight, and easily modularized planar devices for microwave applications.