**Author details**

When loaded the metasurface to the RC, it can act as a tuner. By setting the number of meta-

**Figure 12.** The standard deviations for the field uniformity of the test zone, which loaded the rotatable 1-bit random coding diffusion metasurface in the RC, and the purple lines are the tolerance requirements for the standard deviation of [10]. (a) the x-component, (b) the y-component, (c) the z-component, and (d) the combined of xyz components. Reprinted

The results indicated that the rotatable 1-bit random coding diffusion metasurface can act as a tuner in the RC and it is of great interest as it shows that the metasurface on the wall increases

In this chapter, an overview of key metasurface concepts such as diffusion, anomalous reflection and refraction has been carried out, and their use in wavefront shaping and beamforming applications, followed by a discussion of polarization conversion in few-layer metasurfaces and their related properties have been discussed. An overview of diffusion coding metasurface reveals their ability to realize unique functionalities to reduce the radar crosssection. We also describe diffusion coding metasurfaces that can improve the field uniformity in reverberation chambers. Finally, we conclude by providing our opinions on opportunities and challenges in this rapidly developing research field. These works presented herein provide a glimpse of the opportunities available for advanced EM functional devices based on geometric phase coding metasurface, which may find applications in the future. Moreover,

surface steps to 12, the standard deviation of the field is the one shown in **Figure 12**.

the test zone available by avoiding the stirrer.

with permission from Ref. [9]; Copyright 2018 Scientific Reports.

**4. Conclusion and outlook**

28 Metamaterials and Metasurfaces

Hengyi Sun1,2\*, Changqing Gu<sup>1</sup> , Zhuo Li<sup>1</sup> and Ferran Martin<sup>2</sup>

\*Address all correspondence to: sunhy1123@nuaa.edu.cn

1 Key Laboratory of Radar Imaging and Microwave Photonics, Ministry of Education, College of Electronic and Information Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, China

2 CIMITEC, Departament d'Enginyeria Electrònica, Universitat Autònoma de Barcelona, Barcelona, Spain
