Theoretical Investigation Of Near-invisible Cylindrical Cloak

J.B. Pendry has proposed a coordinate transformation approach to design invisibility cloaks in 2006. However, an ideal cylindrical cloak derived from coordinate transformation is inevitably unphysical at its inner boundary. Therefore it is meaningful to investigate practical designing methods. In this thesis work, three practical designing approaches for cylindrical cloaks are presented.Our first involves a replacement of a thin layer of material at an ideal cloak's inner surface by a homogeneous material layer. The second method investigates a new material component curve. These two approaches effectively avoid the infinities in material parameters, and at the same time produce practical near-ideal invisibility cloaks. The cloaks obtained are perfectly matched in impedance at the outer boundary. We quantitatively show the effect of the transformation order to the proposed cloak's scattering coefficients. In addition, the third approach suggests an electromagnetic cloak, which is simplified by layered structures of homogeneous isotropic materials. We will quantitatively examine the effect of the total number of the homogeneous isotropic layers to this type of cloak's scattering coefficients. These three types of practical invisibility cloaks are helpful to realize a near-ideal invisibility cloak device.