The optical spectroscopy techniques have been used to investigate left-handed behavior of metamaterials as well as the electron-bosonic spectral functions (or Bosonic spectra) of high-transition-temperature superconductors (or high-Tc superconductors) in the research work of this thesis. The periodic double-ring split-ring resonator (SRR) array was one of the first proposed magnetic metamaterials which could give rise to a negative magnetic permeability (μ<0). In the traditional design of negative index metamaterials, the SRR arrays were combined with continuous metallic wires that provide a negative electric permittivity (∊<0). However, the requirement of an unbroken electrical connection between unit cells would be challenging in building contoured devices. In our study, we carefully examine the electromagnetic properties of the double-ring SRR arrays on silicon substrates in the mid-infrared frequency regime experimentally and numerically. For light at normal incidence, we observe that an electric resonance in the outer ring and a magnetic resonance in the inner ring exist at similar frequencies in one of our samples, which suggests that the double-ring SRR array could have simultaneous a negative permittivity and a negative permeability, or a left-handed behavior. Our conjectures are confirmed by the numerical simulations. We also propose a new left-handed metamaterial composed of two single-ring SRRs in each unit cell. The left-handed behaviors in our designs originate from the SRR structure itself only and therefore, there are no metallic continuous wires involved compared to the conventional left-handed SRR metamaterials. The high-Tc superconductor samples studied here are highly under-doped YBa2Cu3O6.35 (YBCO6.35), nearly optimally doped monolayer HgBa2CuO4+ઠ (Hg1201), Zn- and Ni- doped Bi2Sr2CaCu2O8+ઠ (Bi2212) single crystals. We experimentally determine the optical constants of the samples and numerically extract the electronboson spectral functions from the optical scattering rate by either an analytic formula or a maximum entropy inversion technique. We find that the bosonic mode obtained from the optical data is consistent with a peak in the q-averaged susceptibility seen in the magnetic neutron scattering studies. The comparisons of the bosonic spectra between YBCO6.35 and YBCO6.50, monolayer Hg1201 and trilayer Hg1223 (HgBa2Ca2Cu3O8+ઠ), Zn-doped and Ni-doped Bi2212 characterize the variation of the bosonic spectra with the hole concentration, Tc as well as the magnetic and nonmagnetic atom substitution. / Thesis / Doctor of Philosophy (PhD)

Topological phenomena known from solid state physics have been transferred to a variety of other classical and quantum systems. Due to the equivalence of the Hamiltonian matrix describing tight binding models and the grounded circuit Laplacian describing an electrical circuit we can investigate such phenomena in circuits. By implementing different Hermitian topological models general suggestions on designing those types of circuit are worked out with the aim of minimizing unwanted coupling effects and parasitic admittances in the circuit. Here the existence and the spatial profile of topological states as well as the band structure of the model can be determined. Due to the complex nature of electric admittance the investigations can be directly expanded to systems with broken Hermiticity. The particular advantages of the experimental investigation of non-exclusively topological phenomena by means of electric circuits come to light in the realization of non-Hermitian and non-linear models. Here we find limitation of the Hermitian bulk-boundary correspondence principle, purely real eigenvalues in non-Hermitian PT-symmetrical systems and edge localization of all eigenstates in non-Hermitian and non-reciprocal systems, which in literature is termed the non-Hermitian skin effect. When systems obeying non-linear equations are studied, the grounded circuit Laplacian based on the Fourier-transform cannot be applied anymore. By combination of the connectivity of a topological system together with non-linear van der Pol oscillators self-activated and self-sustained topological edge oscillations can be found. These robust high frequency sinusoidal edge oscillations differ significantly from low frequency relaxation oscillations, which can be found in the bulk of the system. / Die vorliegende Dissertation befasst sich mit der Realisierung, dem Nachweis und der Charakterisierung topologieinduzierter Zustände und Phänomene in elektrischen Schaltkreisen, den sogenannten ”topolectric circuits“, motiviert durch Erkenntnisse aus der Festkörperphysik. Hierfur wird die Beschreibung eines elektrischen Schaltkreises mithilfe des Knotenpotentialverfahrens verwendet, welches Potentiale und extern zugeführte Ströme von Schaltungen bestehend aus linearen elektrischen Bauelementen kompakt durch eine Admittanzmatrix miteinander verknüpft. Aufgrund der ̈Aquivalenz eines mithilfe von konzentrierten Bauteilen beschreibbaren Schaltkreises und eines gewichteten Graphens wird der Matrixformalismus in Bezug auf die zugrundeliegende Graphentheorie zum grounded circuit Laplacian Formalismus erweitert. Dieser dient anschließend als Grundlage fur die Verkn üpfung von elektrischen Schaltkreisen und festkörperphysikalischen Modellsystemen mit topologieinduzierten Pänomenen, die nicht auf der quantenphysikalischen Natur des Festkörpers beruhen. Denn der den Kristall beschreibende, quantenmechanische Hamiltonoperator in tight binding (engl. für: enge Bindung) Näherung kann in ̈ahnlicher Matrixschreibweise dargestellt werden. Dadurch können anschließend durch Messungen im Schaltkreis ̈aquivalent aufgrund der ̈Ahnlichkeit der beiden Matrizen Ruckschlüsse auf Elektron-Wellenfunktionen, deren Energien und die elektronische Bandstruktur des Festkörpers gezogen werden. ...

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One of the untapped energy sources is the thermal energy available either from solar irradiance which is still not fully utilized or from the ambient heat temperature. Both resources share the nature of infrared (IR) radiation but with different range of wavelengths. The rectenna (rectifying antenna) concept is presented to harvest these IR radiations. The rectenna is simply an antenna connected to a diode. The diode has to be able to follow and rectify the ultra-fast received AC signal. This condition promotes the use of metal-insulator-metal (MIM) diodes due to their ultra-fast tunneling mechanism. The impedance matching between the diode an antenna is to be considered. The resistance practical ranges of both nano-antenna and MIM diode are generally far. The diode responsivity determines the MIM rectification capability. By building MIM diodes with multiple insulator layers the trade-off between the resistance and responsivity can be resolved. An optimization algorithm to select the qualified materials to build an MIIM diode with high responsivity and low resistance is introduced. A Ti-TiO2/ZnO-Al MIIM diode with ultra-thin oxide layers is fabricated. Also, a global optimization approach is carried out to maximize the impedance matching between the diode and the nano-antenna while improving the capacitance effect on the device’s cut-off frequency. The optimal results reveal a maximum coupling efficiency of 5.5%, a responsivity of 6.4 A/W, and a cut-off frequency of ~34 THz. A symmetric MIM metamaterial perfect absorber is introduced. The design has larger resistance than conventional nano-antennas. The near unity absorptivity is achieved through an optimization approach. A novel Chand-Bali nano-antenna that supports dual polarization and wide angle of reception is presented. The rectenna based on this nano-antenna is expected to achieve more than one magnitude of efficiency higher than ones fabricated in literature. / Thesis / Doctor of Philosophy (PhD)

No / In this paper, low profile planar Metamaterial-Inspired coplanar fed waveguide antenna is presented for WLAN and Ultra-Wideband applications. The antenna is based on a simple strip loaded to a rectangular patch and zigzag E-shape metamaterial-inspired unit cell. The idea behind the proposed antenna is to enable miniaturization effect. The proposed antenna can provide dual band operation, the first one is a Wi-Fi band at 2.45 GHz having impedance bandwidth of 150MHz, the second one is an ultra wide band extended from 4.2 GHz to 6.5 GHz. Two antennas are designed and fabricated with and without metamaterial-inspired loading. The simulated and measured results regarding Return loss (S11), Gain and Radiation pattern are discussed.

Yes / In this paper, a set of singular integral formulations are derived to calculate the surface impedance matrix on the antenna array elements. The proposed mathematical model enables electrodynamic analysis of antenna arrays designed using metamaterial-inspired structures. The formulations allow the determination of the array’s impedance, spatial and polarization characteristics at significantly low computational cost compared to conventional electromagnetic solvers based on method-of-moments (MoM) numerical technique. The accuracy of the surface impedance results obtained from the theoretical formulations are verified using the full wave EM software. It is shown that there is excellent agreement between the proposed formulations and EM software. The accuracy of the theoretical model presented is valid for single layer structures. / RTI2018-095499-B-C31, Funded by Ministerio de Ciencia, Innovación y Universidades, Gobierno de España (MCIU/AEI/FEDER,UE), and innovation programme under grant agreement H2020-MSCA-ITN-2016 SECRET-722424 and the financial support from the UK Engineering and Physical Sciences Research Council (EPSRC) under grant EP/E022936/1

Yes / In this paper a metamaterial-inspired T-matching network is directly imbedded inside the feedline of a microstrip antenna to realize optimum power transfer between the front-end of an RF wireless transceiver and the antenna. The proposed T-matching network, which is composed of an arrangement of series capacitor, shunt inductor, series capacitor, exhibits left-handed metamaterial characteristics. The matching network is first theoretically modelled to gain insight of its limitations. It was then implemented directly in the 50-Ω feedline to a standard circular patch antenna, which is an unconventional methodology. The antenna’s performance was verified through measurements. With the proposed technique there is 2.7 dBi improvement in the antenna’s radiation gain and 12% increase in the efficiency at the center frequency, and this is achieved over a significantly wider frequency range by a factor of approximately twenty. Moreover, there is good correlation between the theoretical model, method of moments simulation, and the measurement results.

Yes / Millimetre-wave frequencies are promising for sensitive detection of glucose levels in the blood, where the temperature effect is insignificant. All these features provide the feasibility of continuous, portable, and accurate monitoring of glucose levels. This paper presents a metamaterial-inspired resonator comprising five split-rings to detect glucose levels at 24.9 GHz. The plexiglass case containing blood is modelled on the sensor's surface and the structure is simulated for the glucose levels in blood from 50 mg/dl to 120 mg/dl. The novelty of the sensor is demonstrated by the capability to sense the normal glucose levels at millimetre-wave frequencies. The dielectric characteristics of the blood are modelled by using the Debye parameters. The proposed design can detect small changes in the dielectric properties of blood caused by varying glucose levels. The variation in the transmission coefficient for each glucose level tested in this study is determined by the quality factor and resonant frequency. The sensor presented can detect the change in the quality factor of transmission response up to 2.71/mg/dl. The sensor's performance has also been tested to detect diabetic hyperosmolar syndrome. The sensor showed a linear shift in resonant frequency with the change in glucose levels, and an R2 of 0.9976 was obtained by applying regression analysis. Thus, the sensor can be used to monitor glucose in a normal range as well as at extreme levels. / This study is funded by Ministry of Higher Education (MoHE) Malaysia under Fundamental Research Grant Scheme Vot No. FRGS/1/2019/TK04/UTHM/02/13, and it is partially sponsored by Universiti Tun Hussein Onn Malaysia (UTHM).

Made available in DSpace on 2014-12-17T14:55:53Z (GMT). No. of bitstreams: 1 MarinaldoPSN_DISSERT.pdf: 999347 bytes, checksum: 61ef641028185e656504321954690c18 (MD5) Previous issue date: 2011-11-25 / Universidade Federal do Rio Grande do Norte / This work presents a theoretical and numerical analysis for the radiation characteristics of rectangular microstrip antenna using metamaterial substrate. The full wave analysis is performed in the Fourier transform domain through the application of the Transverse Transmission Line - TTL method. A study on metamaterial theory was conducted to obtain the constructive parameters, which were characterized through permittivity and permeability tensors to arrive at a set of electromagnetic equations. The general equations for the electromagnetic fields of the antenna are developed using the Transverse Transmission Line - TTL method. Imposing the boundary conditions, the dyadic Green s function components are obtained relating the surface current density components at the plane of the patch to the electric field tangential components. Then, Galerkin s method is used to obtain a system of matrix equations, whose solution gives the antenna resonant frequency. From this modeling, it is possible to obtain numerical results for the resonant frequency and return loss for different configurations and substrates / Esta disserta??o de Mestrado apresenta uma an?lise te?rica e num?ricocomputacional, das caracter?sticas ressonantes de uma antena de microfita com patch retangular utilizando substrato metamaterial. A an?lise utiliza o formalismo de onda completa atrav?s da aplica??o do m?todo da Linha de Transmiss?o Transversa - LTT, no dom?nio da transformada de Fourier. ? realizado um estudo acerca da teoria dos metamateriais com o intuito de obter seus par?metros construtivos, os mesmos s?o caracterizados atrav?s de tensores permissividade e permeabilidade. As equa??es gerais para os campos eletromagn?ticos da antena s?o desenvolvidas aplicando o m?todo da Linha de Transmiss?o Transversa - LTT. A imposi??o das condi??es de contorno adequada ? estrutura permite determinar as fun??es di?dicas de Green, relacionando as componentes da densidade de corrente no patch com as componentes tangenciais do campo el?trico. O m?todo de Galerkin ? ent?o usado para obter a equa??o matricial, cuja solu??o n?o trivial fornece a freq??ncia de resson?ncia da antena. A partir da modelagem ? poss?vel obter resultados para a freq??ncia de resson?ncia em diferentes configura??es de antenas e substratos, al?m da perda de retorno