Wideband circularly-polarized bifunction devices employing composite metasurfaces

Multifunctional device is powerful for promoting the development of a new generation of electromagnetic systems, and the metasurface has attracted much attention in this field due to its flexible control of amplitude, phase, and polarization of the electromagnetic wave. It is very important to achieve different and arbitrary phase distributions for left-handed and right-handed circularly polarized waves in designing circularly polarized lenses. Here, a strategy to control the propagating phase and the geometrical phase simultaneously and independently is proposed by using a gap-loaded ring-shaped composite element. Through adjusting the arm length and the orientation of the unit cell, the propagating phase and geometric phase for the circularly polarized electromagnetic wave can be controlled independently. The combination of above two phases is used to break the inherent relationship between the lef-thanded and right-handed circularly polarized electromagnetic wave, which provides a new method of designing bifunctional devices for circular polarization. On this basis, a circularly polarized deflector with reflections in different planes and a generator with directional and vortex-shape beams are built by using the proposed composite elements. Simulated and measured results show that the bifunctional devices for circular polarization proposed in this paper can work well in a wide frequency range of 9-13 GHz.

Automated summary

The multifunctional devices proposed in this paper, which can control the propagating phase and geometric phase of circularly polarized electromagnetic waves independently, provide a new method for designing bifunctional devices for circular polarization and can work well in a wide frequency range of 9-13 GHz.