Hui, Ka Shing = 梯度的各向異性超材料的廣角度的古斯-漢欣位移 / 許嘉誠. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 78-82). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese. / Hui, Ka Shing = Ti du de ge xiang yi xing chao cai liao de guang jiao du de Gusi-han xin wei yi / Xu Jiacheng.

Includes bibliographical references (p. 58-59).

Thesis (Ph.D.)--University of Delaware, 2009. / Principal faculty advisor: Dennis W. Prather, Dept. of Electrical & Computer Engineering. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 170-175).

The introduction of the so-called metamaterials, artificial materials which have engineered electromagnetic responses that are not readily available in nature, and their exotic properties have provided an alternate design approach that has led to improved performance characteristics of several radiating and scattering systems. This dissertation work introduces an antenna design paradigm based on the incorporation of metamaterials, which have negative permittivity and/or permeability medium properties, with simple radiating elements to obtain efficient electrically-small antenna systems. The most general analytical form of the electrically-small electric dipole antenna in the presence of a multilayered metamaterial shell system is developed and the total radiated power of this system is optimized using a hybrid genetic algorithm(GA)-MATLAB optimization approach. The numerical modeling of more realistic antenna-metamaterial systems confirms the analytical results. The theoretical and numerical studies of their radiation and resonance behaviors have led this dissertation work to the discovery of the first physical two- (2D) and three-dimensional (3D) metamaterial based and inspired efficient electrically-small antenna systems. Several novel metamaterial-inspired electrically-small antenna systems, i.e., the 2D and 3D electrical- and magnetic-based EZ antennas, are reported and are shown to be naturally matched to a 50 Ohms source and, hence, to have high overall efficiencies. The proposed 2D and 3D EZ antenna systems are linearly scalable to a wide range of frequencies. Several versions of the 2D EZ antennas were fabricated and tested. The measurement results confirm the performance predictions. This dissertation also considers several new metamaterial structures. An artificial magnetic conductor (AMC) slab is designed to achieve its in-phase reflection properties in the X-band at 10 GHz without the presence of a PEC ground plane. A block of this AMC structure was designed, fabricated, tested, and then integrated with a dipole antenna to realize a resonant low profile antenna system having a large front-to-back ratio.

Thesis advisor: Krzysztof Kempa / Plasmons are quantized quasiparticles of the electron density waves. When coupled with photons, plasmons become another type of quasiparticles called plasmon polaritons. At the surface of a metal, surface plasmons can be formed. They have confined propagation on the surface, analogous to water waves in a pool. Plasmonic metamaterials manipulate the surface plasmon resonances, achieving a variety of unseen optical properties in nature. For the sake of fast emerging of nano fabrication and characterization techniques in recent years, plasmonic metamaterials have been applied in a wide range of fields, such as broadband absorption in solar cells, negative index materials for cloaking, subwavelength imaging, and wave modulations. One unique property of plasmonic metamaterial is offering remarkable flexibility in controlling effective dielectric properties of matter, depending on the composite design. In this thesis, several concepts of EM response manipulation using plasmonic metamaterials are proposed and studied. These studies include: (1) a scheme assuring topologically protected photonic edge states in the visible range utilizing epsilon-near-zero (ENZ) gyroelectric metamaterials; (2) engineering low frequency dielectric function with extremely subwavelength magnetic resonators; and (3) tailoring the electron-phonon interactions (including controlling superconductivity) by introducing plasmonic resonators into the phonon systems. These works may enable a broad range of applications in both photonic and phonon systems. / Thesis (PhD) — Boston College, 2018. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Physics.

Metamaterials, artificially engineered structures with negative average relative permittivity and permeability, provide a route to creating potential devices with exciting electromagnetic properties that cannot be obtained with natural materials. One particularly interesting metamaterial device, is a planar metamaterial waveguide structure (MWS) that has potentially exciting applications. In this thesis, the properties and potential applications of metamaterial waveguide structures are explored. In particular, we examine the properties of metamaterial waveguides when the limitations arise from fabrication techniques and physical principles are taken into account. First, we study the basic properties of dispersion curves of an idealized (without loss and dispersion) metamaterial waveguide structure. We show that there are a rich variety of modes, such as the bound modes, the surface polariton modes, and the complex leaky modes, that are supported in MWS and have entirely different properties than the modes of a conventional waveguide structure. These novel modes provide more control over the electromagnetic fields and consequently lead to potential applications ranging from waveguide miniaturization to the slowing down of the light. Next, we study the effects of dispersion and loss, which are the inherent features of metamaterials, on the properties of MWS. We numerically show that the characteristic modes of the MWS are significantly changed particularly near the slow-light-modes when the intrinsic loss is introduced into the system. In particular we show that the stopped-light-modes disappear even in the presence of an arbitrarily small amount of loss. Moreover, we find several novel properties such as a splitting of complex leaky modes in a lossy MWS. / Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2008-10-31 14:47:47.054

In this thesis metamaterial radar absorbers and plasmonic structures have been investigated. Following a brief overview covering metamaterial structures, and their applications in various areas of Microwave Engineering, a novel thin metamaterial wideband radar absorber, formed by two layers of resistive Hilbert curve arrays, is proposed and analysed numerically in HFSS, revealing a reduction in Monostatic Radar Cross Section (RCS) of more than 10 dB from 9.1 to 18.8 GHz (70% fractional bandwidth) for both polarizations. The structure has thickness of only 0.11λ to 0.24λ at lowest and highest frequencies respectively. The lateral dimensions are only 0.13λ to 0.3λ per unit cell at lowest and highest frequencies respectively which is several times smaller than that of recently reported circuit analogue absorbers operating in the similar frequency band. Furthermore, a wideband terahertz Hilbert curve array is proposed and analyzed both theoretically and numerically, showing an absorption bandwidth of more than one octave. This was followed by study of plasmonic cloak for subwavelength conducting objects. It was demonstrated that a plasmonic cloak designed for a conducting sphere will work for non spherical conducting objects of similar dimensions as well. Finally spoof plasmonic structures were investigated. A novel plasmonic structure based on a modified Apollonian fractal array of cylindrical coaxial apertures in an aluminium sheet was proposed and analyzed. The structure exhibits negative group velocity with less than 3.5 dB attenuation. Plasmonic structure based on Sierpinski array of apertures was also investigated and found to give quite good extraordinary transmission bandwidth.

Les antennes dédiées à la guerre électronique (GE), ont des bandes passantes qui peuvent dépasser la décade (rapport 10 entre les fréquences haute et basse), avec une fréquence basse proche d’une centaine de MHz. Les antennes classiques principalement utilisées dans le domaine de la GE font appel à des antennes dites indépendantes de la fréquence, qui sont placées au-dessus d’une cavité absorbante. Cependant, l’épaisseur de la cavité est importante compte tenu de la fréquence basse de fonctionnement de l’antenne utilisée. Ceci complexifie l’intégration de ces antennes sur des porteurs de petite taille où le volume est restreint et la masse un paramètre critique. Afin de concevoir de nouveaux systèmes antennaires dédiés à la GE plus performants, il convient d’opérer une rupture technologique des solutions actuelles. Cette rupture passe par le remplacement de la cavité absorbante qui emploie des matériaux lourds, onéreux et non reproductibles par des solutions innovantes comme celles que proposent les métamateriaux et notamment les conducteurs magnétiques artificiels (CMA). Pour nos travaux, nous avons sélectionné deux antennes, une antenne spirale d’Archimède et une antenne sinueuse. Une analyse du champ proche de ces deux antennes a été proposée et validée partiellement par une mesure innovante. Cette analyse a permis de donner une loi de variation de la zone active de l’antenne à grande proximité de celle-ci, afin de pouvoir dimensionner un réflecteur placé au plus près de l’antenne. Nous avons présenté et validé les différents types de réflecteurs qui peuvent être associés à ce type d’antenne, qu’il s’agisse d’un conducteur électrique parfait (CEP), ou d’un conducteur m / Antennas dedicated to electronic warfare (EW), operate on bandwidth higher than a decade (ratio 10 between the high and low frequencies), with the low frequency close to one hundred MHz. Antennas usually used in the field of EW are independent frequency antennas, which are placed above an absorber cavity. However, the thickness of the cavity is important regarding the antenna lower operating frequency. This complicates the integration of these antennas on small carriers where the volume is limited and the mass is a critical parameter. In order to develop new more efficient antenna systems dedicated to the EW, it is necessary to operate a technological break of current solutions. This break consists of replacing the cavity absorber employing heavy, expensive and no reproducible materials by innovative solutions as those proposed by metamaterials such as artificial magnetic conductor (AMC). In my work, we selected two antennas, an Archimedean spiral antenna and a sinuous antenna. An analysis of the electromagnetic near field of the antennas has been proposed and partially validated by an innovative measurement. Thanks to this analysis, it is possible to give the variation distribution of the active area of the antenna close to this one, in order to design a reflector placed very close to the antenna. We have exposed and validated the different types of the reflectors that can be associated with this type of antenna, whether it is a perfect electric conductor (PEC) or a perfect magnetic conductor (PMC). The results proved that a wideband bidirectional antenna place above a PEC reflector has a maximal band of interest (MBI) of 5:1, in this bandwidth the broadside gain of the

As natural chiral materials demonstrate limited circularly dichroic contrasts, enhancement of these polarization dependent signals has long been the focus of chiral metamaterial research. By manipulating the geometric chirality of resonant plasmonic nanostructures, we are capable of enhancing light confinement to amplify chiral modified, nonlinear signals from quantum emitters. The metamaterial demonstrates a linear transmission contrast of 0.5 between left and right circular polarizations and a 20× contrast between second harmonic responses from the two incident polarizations. Nonlinear and linear response images probed with circularly polarized lights show strongly defined contrast. As a second set of experimentation, the chiral center of the metamaterial is opened, providing direct access to place emitters to occupy the most light-confining and chirally sensitive regions. The resulting two-photon emission profiles from circularly polarized excitation displays mirrored symmetry for the two enantiomer structures. The efficiency of the nonlinear signal directly correlates to the chiral resonance of the linear regime. The nonlinear emission signal is enhanced by 40× that of the emitters not embedded in the metamaterial and displays a 3× contrast for the opposite circular polarization. Such manipulations of nonlinear signals with metamaterials open pathways for diverse applications where chiral selective signals are monitored, processed, and analyzed.