DESIGN AND ANALYSIS OF METAMATERIAL ABSORBERS

Abstract

As the communication technology is advancing at a rapid pace, demand for highly efficient devices is also growing. Metamaterials are developed as a new technology in communication, physics and material science in the recent decades, particularly in the field of microwave communication. There is a lot of research going on right now to develop metamaterial structures that can used in developing more advanced ways of communication. Since the introduction of metamaterials in 1968 by a Victor Veselago [1] by a speculation of existence of “simultaneous negative permittivity and permeability”. Since then, a tremendous amount of research in the field of metamaterials has been carried out. Metamaterials are classified as such artificial structures which have some unique properties that not easily found in nature. Such properties are negative permittivity, negative permeability which results in negative refractive index. They are also called as double-negative media (DNG) and left-handed structure. Generally, metamaterials consist of small elements known as unit cell which are then repeated periodically to form a homogenous metamaterial. The size of the MA unit cell must be smaller than the one fourth of the resonant wavelength to achieve homogenization. It was also found out that these materials can change the behavior of electromagnetic waves in unexpected ways. The main focus of this report is on Metamaterial absorbers. Chapter 1 given a brief introduction about metamaterial and metamaterial absorbers along with the applications of metamaterial in filter, antennas, absorber, super lenses etc. In this chapter a brief introduction about the terminologies related to metamaterials is also given. Chapter 2 presents review of some previous literature on metamaterial absorbers described in three section narrowband absorber, multiband absorber and broadband absorbers. Chapter 3 presents the design of an ultrathin perfect metamaterial-absorber based on dual split-ring with a cross-resonator designed on an ultrathin low cost FR4 substrate with a thickness of 1.6mm (0.026λo corresponding to the resonant frequency) and unit cell size of 8x8 mm2 . The proposed absorber has 99.99% absorptivity at 5.02 GHz in C-band. The permittivity, permeability and normalized impedance have been calculated to find the impedance matching of the proposed structure. The structure has also been analyzed by varying different design parameters. To study the effect the rotational angle of splits the proposed structure was rotated 45o clockwise and absorption response have been analyzed, the rotated structures have multiband absorption response in X-band and Ku-band.