Metamaterial-Based Cylinders Used for Invisible Cloak Realization
Final rept. 23 Jul 2010-23 Jul 2011
ZAGREB UNIV (CROATIA) FACULTY OF ELECTRICAL ENGINEERING AND COMPUTING
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The realization of structures that do not scatter electromagnetic field, i.e. structures that appear invisible for EM waves is not a new concept. The possibility of a plane wave passing through some structure without distortions i.e. with zero scattered field has been investigated theoretically since 1960s see e.g. 1-4. Recently, the possibility of cloaking objects using a metamaterial cover has extensively been studied 5-7. In this approach, material has been used to render a volume effectively invisible to incident radiation, i.e. to squeeze space from a volume into a shell surrounding the concealment volume. Coordinate transformations that are used for cloak design do not influence the form of Maxwell s equations, but they affect permittivity and permeability tensors 949 and 956 respectively, making the needed materials spatially varying and anisotropic. When viewed externally, the concealed volume and the cloak both appear to have the propagation properties of free space, i.e. they appear invisible to electromagnetic waves. The required anisotropy is supposed to be obtained by using metamaterials. The main realized outcomes of the project is the development of the program UniaxCloak that analyzes cylindrical and spherical cloaks made from the uniaxial materials. The program can fully characterize uniaxial cloaks, i.e. it calculates scattered width and total scattered width in a frequency range of interest. In the cylindrical case, the incident wave can have arbitrary angle of incidence. And we have made a detailed investigation of properties of cloaks that are made from uniaxial materials. In practice, such cloaks can be made from metamaterials, for example from split-ring periodic structures or periodic wire structures.
- Radiofrequency Wave Propagation