Amplitude and phase control of double-sided metal metasurface microstructure

Abstract Metasurface refers to a layer of subwavelength microstructures (less thick than the operating wavelength) present at the interface that extends periodically or aperiodically in a certain direction on the plane. Electromagnetic wave passing through the metasurface will produce phase mutation, and the propagation of electromagnetic wave can be controlled by the resulting phase mutation. Based on the above properties, metasurfaces show growth potential in the design of ultra-thin electromagnetic devices, such as ultra-thin metasurface lenses, spin orbit manipulation, metasurface holograms, and some other functional devices. Today’s metasurfaces mostly focus on realizing phase control, ignoring amplitude control, which needs to be carried out simultaneously to fully manipulate the propagation of electromagnetic waves. In some important applications, such as holography, laser beam shaping, and complex wave field synthesis, these two degrees of freedom need to be manipulated to generate high-quality holographic images. We design a metasurface consisting of a C-shaped antenna array to control its phase and amplitude by changing its geometry and rotation direction, respectively. We demonstrate that independent control of amplitude and phase can be achieved in frequencies from 0 to 8.5 GHz. Since the working efficiency of single layer metasurface is slightly low at 4.6 GHz, the diffraction effect may be affected to some extent. Therefore, at this frequency, we use a metal–copper double-sided C-type design to simultaneously control the amplitude and phase of electromagnetic waves through the metasurface. By setting the C-shaped metal copper structure with different geometry and rotation direction, the amplitude and phase of the incident electromagnetic wave can be changed. This design can realize arbitrary continuous phase and amplitude regulation, so as to realize the free control of transmitted electromagnetic waves. Experimentally, we prepared the designed metasurface structure and measured the far-field scattering properties of the metasurface using a microwave test system. The experimental and theoretical results agree well.