Invisible Cloak Design and Application of Metasurfaces on Microwave Absorption and RCS Reduction

Increasing attention to metamaterials has been attracted by researchers due to their unusual electromagnetic properties. One of the intriguing metamaterial devices is the cloak. In the first part of this chapter, we first review two popular methods, including the coordinate transformation method and scattering cancellation approach to design invisibility and illusion cloaking devices. The coordinate transformation-based method as an intuitive and visual approach, offers unprecedented flexibility in the design of the complementary cloaking devices. The scattering cancellation-based cloaking design can be analytically achieved in the Mie series method and characteristic mode (CM) method framework. With some selected examples, we illustrate the invisibility and illusion capabilities of the cloaking devices designed by two methods. On the other hand, metasurface-based microwave absorption and radar cross section (RCS) reduction have attracted much attention in the field of stealth for safety. Especially, the antenna designs with low RCS characteristics become crucial for stealth platform communication. Thus the RCS reduction of antennas without compromising their radiation characteristics has been a topic of immense strategic interest. The second part of this chapter gives some interesting examples of metasurfaces, i.e., perfect metamaterial absorber (PMA) and artificial magnetic conductor (AMC). Experimental verification of their predicted behaviors has been obtained. These antennas with metasurface have led to a wide variety of in-band and broadband RCS reductions.