The design, modeling, fabrication, and validation of an optical magnetic response in dielectric-based metamaterials are studied. These metamaterials consist of either periodic or random arrays of dielectric particle inclusions, which may be spheres, coated spheres, or completely randomly shaped. It is demonstrated that because of the simple particle shapes and dielectric materials, these metamaterials are quite easy and feasible to implement in a bulk, three-dimensional sample, and the response is isotropic. This in is contrast to other predominant designs of optical metamaterials, which are planar and anisotropic arrays of complicated metallic fishnet or split-ring resonator structures, which require stringent tolerances and sophisticated assembly. It is shown that SiC is one of many materials from which such infrared magnetic metamaterials can be constructed. A simple SiC powder is used to verify these claims. The milled micropowder of crystalline SiC is comprised of particles of random shapes and sizes. A model of the electromagnetic response of such powders is developed, whereby the induced magnetic dipole response is modeled by equivalently-sized spheres of SiC, whereas the electric dipole response is modeled by a continuous distribution of ellipsoidal particles. Infrared spectroscopic measurements and numerical calculations are performed, verifying both the magnetic and electric response of the powder. A alternate approach is also described, where uniform SiC microspheres are fabricated using more sophisticated nanochemical techniques. In the final portion of the dissertation, the mutual near-field coupling between ideal magnetic dipoles induced in dielectric spheres is studied. This is implemented for microwave frequencies using large permittivity ceramic spheres. An approximate coupled dipole model of the multiple scattering among the spheres is developed, and a transition matrix method is implemented to calculate the exact scattering by the clusters. Experimental measurements are performed, confirming the two models. The results for pairs, chains, and rings of spheres indicates that the magnetic dipole modes hybridize in analogy to atomic bonding. A notable result is that certain hybridized magnetic dipole modes may have a net electric dipole moment. The similarity to atomic and molecular bonding should prove useful in conceptualizing and designing more sophisticated metamaterials.

The design, modeling, fabrication, and validation of an optical magnetic response in dielectric-based metamaterials are studied. These metamaterials consist of either periodic or random arrays of dielectric particle inclusions, which may be spheres, coated spheres, or completely randomly shaped. It is demonstrated that because of the simple particle shapes and dielectric materials, these metamaterials are quite easy and feasible to implement in a bulk, three-dimensional sample, and the response is isotropic. This in is contrast to other predominant designs of optical metamaterials, which are planar and anisotropic arrays of complicated metallic fishnet or split-ring resonator structures, which require stringent tolerances and sophisticated assembly. It is shown that SiC is one of many materials from which such infrared magnetic metamaterials can be constructed. A simple SiC powder is used to verify these claims. The milled micropowder of crystalline SiC is comprised of particles of random shapes and sizes. A model of the electromagnetic response of such powders is developed, whereby the induced magnetic dipole response is modeled by equivalently-sized spheres of SiC, whereas the electric dipole response is modeled by a continuous distribution of ellipsoidal particles. Infrared spectroscopic measurements and numerical calculations are performed, verifying both the magnetic and electric response of the powder. A alternate approach is also described, where uniform SiC microspheres are fabricated using more sophisticated nanochemical techniques. In the final portion of the dissertation, the mutual near-field coupling between ideal magnetic dipoles induced in dielectric spheres is studied. This is implemented for microwave frequencies using large permittivity ceramic spheres. An approximate coupled dipole model of the multiple scattering among the spheres is developed, and a transition matrix method is implemented to calculate the exact scattering by the clusters. Experimental measurements are performed, confirming the two models. The results for pairs, chains, and rings of spheres indicates that the magnetic dipole modes hybridize in analogy to atomic bonding. A notable result is that certain hybridized magnetic dipole modes may have a net electric dipole moment. The similarity to atomic and molecular bonding should prove useful in conceptualizing and designing more sophisticated metamaterials.

In recent years, there has been an increasing interest on left handed metamaterials because of their possible innovative applications. The pioneer study introducing such materials was brought out by V. G. Veselago in 1968 [1]. In his work, Veselago proposed a medium having simultaneously negative electric permittivity and magnetic permeability and investigated its electromagnetic characteristics. He found out that the electric field, magnetic field and the propagation vector form a left handed triplet, thus named such materials as &ldquo / Left Handed Materials&rdquo / . Despite the significance of Veselago&rsquo / s inferences, the metamaterial theory stayed dormant for nearly 30 years. Towards the end of 1990s, the physically realizable left handed materials were built as the combination of two periodical structures / Split Ring Resonators (SRRs) and metallic thin wire arrays [4-5]. In this thesis, electrical and magnetic characteristics of the left handed metamaterials are theoretically investigated by using the analytical models for their permittivity and permeability functions with respect to frequency. For this purpose, first, two basic metamaterial structures / the Split Ring Resonators and Thin Metallic Wire Arrays are studied individually and their electrical and magnetic characteristics are examined. Finally, the composite left handed structure containing both SRRs and thin wires is studied to investigate the resulting simultaneous resonance properties and to estimate their overall effective permeability and permittivity functions.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21732号 / 工博第4549号 / 新制||工||1709(附属図書館) / 京都大学大学院工学研究科電気工学専攻 / (主査)教授 大村 善治, 教授 松尾 哲司, 教授 竹内 繁樹 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Made available in DSpace on 2014-12-17T14:54:58Z (GMT). No. of bitstreams: 1 DaviBB_DISSERT_1-70.pdf: 4567680 bytes, checksum: 150ff5afc1806ca374278b4c00a1f5a3 (MD5) Previous issue date: 2010-12-06 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Metamaterials exhibiting negative refraction have attracted a great amount of attention in recent years mostly due to their exquisite electromagnetic properties. These materials are artificial structures that exhibit characteristics not found in nature. It is possible to obtain a metamaterial by combining artificial structures periodically. We investigated the unique properties of Split Ring Resonators, High impedance Surfaces and Frequency Selective Surfaces and composite metamaterials. We have successfully demonstrated the practical use of these structures in antennas and circuits. We experimentally confirmed that composite metamaterial can improve the performance of the structures considered in this thesis, at the frequencies where electromagnetic band gap transmission takes place

Yes / In this review paper, a comprehensive study on the concept, theory, and applications of composite right/left-handed transmission lines (CRLH-TLs) by considering their use in antenna system designs have been provided. It is shown that CRLH-TLs with negative permittivity (ε <; 0) and negative permeability (μ <; 0) have unique properties that do not occur naturally. Therefore, they are referred to as artificial structures called “metamaterials”. These artificial structures include series left-handed (LH) capacitances (C L ), shunt LH inductances (L L ), series right-handed (RH) inductances (LR), and shunt RH capacitances (CR) that are realized by slots or interdigital capacitors, stubs or via-holes, unwanted current flowing on the surface, and gap distance between the surface and ground-plane, respectively. In the most cases, it is also shown that structures based on CRLH metamaterial-TLs are superior than their conventional alternatives, since they have smaller dimensions, lower-profile, wider bandwidth, better radiation patterns, higher gain and efficiency, which make them easier and more cost-effective to manufacture and mass produce. Hence, a broad range of metamaterial-based design possibilities are introduced to highlight the improvement of the performance parameters that are rare and not often discussed in available literature. Therefore, this survey provides a wide overview of key early-stage concepts of metematerial-based designs as a thorough reference for specialist antennas and microwave circuits designers. To analyze the critical features of metamaterial theory and concept, several examples are used. Comparisons on the basis of physical size, bandwidth, materials, gain, efficiency, and radiation patterns are made for all the examples that are based on CRLH metamaterialTLs. As revealed in all the metematerial design examples, foot-print area decrement is an important issue of study that have a strong impact for the enlargement of the next generation wireless communication systems. / This work was supported in part by the Ministerio de Ciencia, Innovación y Universidades, Gobierno de España (MCIU/AEI/FEDER, UE) under Grant RTI2018-095499-B-C31, in part by the Innovation Programme under Grant H2020-MSCA-ITN-2016 SECRET-722424, and in part by the financial support from the U.K. Engineering and Physical Sciences Research Council (EPSRC) under Grant EP/E022936/1.