Metasurfaces provide unprecedented routes to manipulations on electromagnetic waves, which can realize many exotic functionalities. Despite the rapid development of metasurfaces in recent years, the design process of metasurface is still time‐consuming and computational resource‐consuming. Moreover, it is quite complicated for layman users to design metasurfaces as plenty of specialized knowledge is required. In this work, a metasurface design method named REACTIVE is proposed on the basis of deep learning, as deep learning method has shown its natural advantages and superiorities in mining undefined rules automatically in many fields. REACTIVE is capable of calculating metasurface structure directly through a given design target; meanwhile, it also shows the advantage in making the design process automatic, more efficient, less time‐consuming, and less computational resource‐consuming. Besides, it asks for less professional knowledge, so that engineers are required only to pay attention to the design target. Herein, a triple‐band absorber is designed using the REACTIVE method, where a deep learning model computes the metasurface structure automatically through inputting the desired absorption rate. The whole design process is achieved 200 times faster than the conventional one, which convincingly demonstrates the superiority of this design method. REACTIVE is an effective design tool for designers, especially for laymen users and engineers.

Metasurfaces have provided unprecedented freedom for manipulating electromagnetic waves. In metasurface design, massive meta-atoms have to be optimized to produce the desired phase profiles, which is time-consuming and sometimes prohibitive. In this paper, we propose a fast accurate inverse method of designing functional metasurfaces based on transfer learning, which can generate metasurface patterns monolithically from input phase profiles for specific functions. A transfer learning network based on GoogLeNet-Inception-V3 can predict the phases of 2^8×8 meta-atoms with an accuracy of around 90%. This method is validated via functional metasurface design using the trained network. Metasurface patterns are generated monolithically for achieving two typical functionals, 2D focusing and abnormal reflection. Both simulation and experiment verify the high design accuracy. This method provides an inverse design paradigm for fast functional metasurface design, and can be readily used to establish a meta-atom library with full phase span.

Metasurfaces, composed of 2D planar arrays of sub-wavelength metallic or dielectric scatterers, have provided unprecedented freedoms in manipulating electromagnetic (EM) waves upon interfaces. The development of metasurface has always been closely related to antennas. On one hand, metasurface was developed from reflect- /transmit-arrays that are used as reflectors/lens of antennas, and most fundamental theories of metasurfaces are directly borrowed from antenna array theories; on the other hand, the development of antennas was flourished and expedited by progresses in metasurfaces. Many emerging antenna configurations have been constructed based on unique functional metasurfaces. In this paper, we will review briefly the development roadmap of both metasurfaces and metasurface-based antennas, including antenna-inspired metasurfaces, metasurface-assisted antennas and metasurface antennas. In particular, the recent fusion of metasurface and antenna as metantenna will bring significant impacts on methodologies of functional metasurface, antenna design, and radio-frequency device miniaturization.

Lightweight structures with multi-functions such as electromagnetic wave absorption and excellent mechanical properties are required in spacecraft. A three-dimensional metamaterial absorber consisting of honeycomb and resistive films was proposed and fabricated through 3D printing and silk-screen printing technology. According to simulation and experiment results, the present three-dimensional metamaterial absorber can realize an absorptivity of more than 90% in a wide band of 3.53–24.00 GHz, and improve absorbing efficiency for transverse magnetic (TM) waves of oblique incidence angle from 0° to 70°. The compression test results reveal that compressive strength of the 3D printed honeycomb can reach 10.7 MPa with density of only 254.91 kg/m³, and the energy absorption per volume W _v and per unit mass W _m are 4.37 × 10³ KJ/m³ and 17.14 KJ/Kg, respectively. The peak compressive strength and energy absorption per mass are at least 2.2 and 3 times comparing to metallic lattice cores with the same density. Outstanding electromagnetic wave absorption and mechanical performance make the present three-dimensional metamaterial absorber more competitive in engineering applications.

In this paper, a transparent metamaterial absorber (MA) loaded with water substrate is presented, which can simultaneously achieve enhanced broadband microwave absorption and tunable infrared radiation. As a proof, the indium tin oxide (ITO) films are first introduced here as a frequency selective surface (FSS) on the top layer and reflective backplane on the ground layer. Next the distilled water combined with the polymethyl methacrylate (PMMA) substrate is employed as a hybrid substrate in the middle. Simulation and experimental measurements show that the transparent water-substrate MA can achieve broadband microwave absorption with efficiency over 90% in the frequency band of 6.4-23.7GHz, and the proposed hybrid substrate has almost no influence on its original transmittance. Moreover, owing to the available water circulation system, the infrared radiation of the proposed MA is also demonstrated to be controlled by the temperature of the injected water. Based on its multifunction and high performance, it is expected that the proposed design may find potential applications, such as glass window of stealth equipment, electromagnetic compatible buildings/facilities, etc.

Lossless coding metasurfaces and metamaterial absorbers have been widely used for radar cross section (RCS) reduction and stealth applications, which merely depend on redirecting electromagnetic wave energy into various oblique angles or absorbing electromagnetic energy, respectively. Here, an absorptive coding metasurface capable of both the flexible manipulation of backward scattering and further wideband bistatic RCS reduction is proposed. The original idea is carried out by utilizing absorptive elements, such as metamaterial absorbers, to establish a coding metasurface. We establish an analytical connection between an arbitrary absorptive coding metasurface arrangement of both the amplitude and phase and its far-field pattern. Then, as an example, an absorptive coding metasurface is demonstrated as a nonperiodic metamaterial absorber, which indicates an expected better performance of RCS reduction than the traditional lossless coding metasurface and periodic metamaterial-absorber. Both theoretical analysis and full-wave simulation results show good accordance with the experiment.