Design Of Two New Types Of Negative Refraction Materials

Since the negative index materials(NIRs) were acquired the breakthrough in theory and the confirmation in experiment, the new type of materials have been the focus of research. The NIRs at microwave frequencies, terahertz and infrared spectrums, and even light spectrum have been designed and realized. NIRs are a kind of composite materials with negative permittivity and permeability at the same frequency band. When the electromagnetic wave transmits in NIRs, the electric field E, magnetic filed H, and wave vector K form a left-hand spiral relationship, therefore they are also called left-hand materials (LHMs). Because the wave vector of electromagnetic wave transmitted in NIRs is in the opposite direction to the energy flow direction, the NIRs present a lot of new features different from those of the conventional medium.In this paper, we design two new NIRs with different unit structures. The results by numerical simulation and S-parameter inversion method show that these two materials can achieve a single-band and dual-band negative index, respectively. In addition, we study the influence of the parameters of structure units of the NIRs on the macro-electromagnetic parameters and present the optimized design.The contents of this paper are arranged as follows:In Chapter 1, we introduce the fundamental theory and the novel characteristics of the NIRs, and summarize the development both at home and abroad.In Chapter 2, we review the classical S-parameter inversion method for the subsequent analysis and simply introduce the simulation software HFSS.In Chapter 3, we propose a new NIR structure composed of revised resonance rings-cross wires units. We extract the S parameters by HFSS and obtain the macro-electromagnetic parameters such as the dielectric permittivity, magnetic permeability, wave impedance and refractive index by S-parameter inversion method. The obtained results show that the material can achieve single-band negative index from 21 GHz to 24.5 GHz. In addition, we analyze the influence of the structural parameters of material unit on the macro-electromagnetic parameters by changing the size of the structure. Then we present the curves of the dielectric permittivity, magnetic permeability, wave impedance and refractive index under the optimized sizes of the unit according to the result of optimized analysis.In Chapter 4, we use a modified "8" rectangular metal ring respectively etching on both sides of the dielectric substrate of FR-4 as a unit to design a NIR. It is found by simulation that the structure may achieve negative refractive bands from 17.3GHz to 17.8GHz and from 20.2GHz to 21.2GHz. Furthermore, through the analysis of influence of the structural unit size on the electromagnetic parameters, we make a optimization design.We draw a conclusion in Chapter 5.