STUDY OF MICROWAVE METASURFACE CLOAK

Abstract

Cloaking is the phenomenon of rendering a visible object invisible. This thesis aims to expand on the functionalities of passive metasurface for the cloaking of cylindrical objects in microwave regime. First, a single-layer dual-band cloak is presented. The cloaking layer features dual-resonance unit cells to fulfil the derived sheet impedances. Second, an azimuthally inhomogeneous metasurface (AIM) cloak is investigated. The AIM features location dependent sheet impedances to promote scattering cancellation. A single-layer AIM improves the cloaking of a 0.15λ (λ is the cloaking wavelength) radius cylinder by more than 6 dB compared to homogeneous metasurface cloak. A three-layer AIM is capable of cloaking, beyond the quasi-static limit, a 0.27λ radius cylinder. Last, a metasurface loaded transformation-optics-based cloak is studied. Instead of a virtual point, a metasurface cloaked cylinder is proposed as a substitute for the transformation. The proposed method eliminates the singularities of the constitutive parameters in the transformed space.