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Characterizing artificial electromagnetic materials and their hybridization with fundamentally resonant magnetic materials

  • Author(s): Gollub, Jonah Nathan
  • et al.
Abstract

The development of a new class of artificial materials, called metamaterials, can be harnessed to provide a wide range of electromagnetic properties beyond those of natural materials. These properties include positive and negative permeability and permittivity values, strong anisotropy, and the ability to construct spatially varying electromagnetic properties within the material. These unconventional electromagnetic materials have been used to demonstrate negative refraction and a cloaking structure among other interesting phenomena. To achieve their response, metamaterials employ periodic composite structures consisting of conductors and dielectrics that are shaped in various geometries which couple to incident electromagnetic waves. In this dissertation we investigate the introduction of fundamentally resonant materials into these geometrically resonant metamaterial structures. We are able to analytically characterize the unique hybridization that occurs. More specifically, we consider the integration of a resonant gyromagnetic materials into waveguide and bulk metamaterial structures. These hybrid structures are shown to provide a means of making strongly tunable metamaterial structures. In this dissertation we initially investigate the physical nature of metamaterial structures. In chapter 2, we consider the effect of geometrical disorder in the resonant elements of a split- ring resonator (SRR) metamaterial and the resulting bulk constitutive parameters. In chapter 3, we consider the potential for metamaterials to support novel surface modes. We experimentally demonstrate the excitation of magnetic surface polariton modes on a magnetic SRR metamaterial slab. In chapter 4, as a precursor to considering how to integrate naturally magnetic materials into metamaterial structures, we consider ferromagnetic materials and their integration into small dimensional microstrip structures. We develop simulation techniques that accurately reproduce experimental results for these analytically intractable structures. In chapter 5, we examine the metamaterial concept in the transmission line environment and consider the potential for constructing tunable metamaterial structures. Finally, in chapter 6, we theoretically and numerically consider a metamaterial with incorporated naturally resonant magnetic material and demonstrate that it exhibits a unique hybrid resonance. In chapter 7, we extend our analysis to a bulk hybrid metamaterial structure with integrated gyromagnetic material. In general, these hybrid structures show potential for extending the electromagnetic properties of metamaterials. They also provide a means of magnifying and decoupling the electromagnetic properties of the integrated resonant magnetic materials

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