Comprehensive Study on the Electromagnetic Properties of Left-handed Combined Metamaterials

Abstract

Not only our conception of wave-matter interactions has been changed recently, but also a new paradigm for understanding the electromagnetic-wave propagation has been re-mapped by the appearance of a new class of materials, the so-called left-handed materials (LHMs). A combination of cut-wire pair (CWP) and continuous wires is widely recognized in constructing the LHMs. This thesis considers the characteristics of CWPs, continuous wires, and combined-metamaterial structures consisting of CWPs and continuous wires. I show a comprehensive study on the electromagnetic properties of LH combined structure.

Chapter one serves as an introduction to the metamaterials outlining the key pieces of works which first created and induced interests in this field. I further look at the progresses which have been made so far, both experimentally and theoretically, and other important applications. The second Chapter gives a theoretical background for the negativities of permeability, permittivity and refractive index of metamaterial-based media. By expanding the previous studies, a simple but complete derivation of a new ??-?? map for isotropic LH media is presented. It is shown that the true possibilities for negative-refractive-index behavior in media are wider than what has been obtained from the old derivation. In the third, I demonstrate the LH behavior at 13.8 GHz of a combined-metamaterial structure, which consists of CWPs and continuous wires. Then I apply the conditions for LH media to explain the single- and the double-negative refractive indices in the combined structure.

The fourth Chapter considers comprehensively the dimensional effects on the electromagnetic properties of combined structure, such as the size dependence, the influence of respectively geometric parameters of CWP and continuous wire as well as the relative position between CWP and continuous wire. These are important results which greatly deal with controlling the performance of LH behavior in combined structure. Finally, a summary of the work in this thesis is given in Chapter five.