A programmable metasurface with dynamic polarization, scattering and focusing control

Abstract

Diverse electromagnetic (EM) responses of a programmable metasurface with a relatively large scale have been investigated, where multiple functionalities are obtained on the same surface. The unit cell in the metasurface is integrated with one PIN diode, and thus a binary coded phase is realized for a single polarization. Exploiting this anisotropic characteristic, reconfigurable polarization conversion is presented first. Then the dynamic scattering performance for two kinds of sources, i.e. a plane wave and a point source, is carefully elaborated. To tailor the scattering properties, genetic algorithm, normally based on binary coding, is coupled with the scattering pattern analysis to optimize the coding matrix. Besides, inverse fast Fourier transform (IFFT) technique is also introduced to expedite the optimization process of a large metasurface. Since the coding control of each unit cell allows a local and direct modulation of EM wave, various EM phenomena including anomalous reflection, diffusion, beam steering and beam forming are successfully demonstrated by both simulations and experiments. It is worthwhile to point out that a real-time switch among these functionalities is also achieved by using a field-programmable gate array (FPGA). All the results suggest that the proposed programmable metasurface has great potentials for future applications.

Error Analysis of Programmable Metasurfaces for Beam Steering

“…The addition of control methods, together with the tunability on a per-cell basis, enables the programming of coding metasurfaces [17], [60], [61]. The example in [46] uses a Field-Programmable Gate Array (FPGA) to drive the pin diodes of a reconfigurable metasurface, where each pin diode determines the binary state of an individual unit cell. Such a device, however, exemplifies the potential reliability issues of programmable metasurfaces.…”

“…Further, we model the scattering pattern of the unit cell over the positive semisphere with the function cos(θ), which is a widespread assumption [46]. Finally, and without loss of generality, we consider the normal incidence (θ i = φ i = 0).…”

Using Intelligent Reflecting Surfaces for Rank Improvement in MIMO Communications

“…An intelligent reflecting surface (IRS) is a thin two-dimensional metamaterial (i.e., engineered material) that can control and transform electromagnetic waves [1,2]. It has been demonstrated experimentally that metasurfaces can dynamically produce unusual scattering, polarization, and focusing properties to obtain desired radiation patterns [3,4]. Thanks to rapid recent development in lumped elements such as micro-electro-mechanical-systems (MEMS), varactors and PIN diodes, and tunable materials such as liquid crystals and graphene, metasurfaces with flexible functionalities can be successfully realized with low implementation cost and light weight [5].…”

Smart monopole antenna with pattern and frequency reconfiguration characteristics based on programmable metasurface

“…These specially designed metamaterials and metasurfaces have been described by effective medium parameters. The material properties can be defined in terms of electromagnetic characteristics . Medium parameters such as effective permeability and permittivity can be adapted to achieve values beyond natural materials.…”