Two laptop antennas are presented using two different designs based on metamaterials. The first design consists of planar monopole loaded with an electric-LC resonator (ELC). This novel topology allows for the realization of a multi-band antenna by using the ELC to add multiple resonances. This structure is analyzed using full-wave simulations. A circuit model is also developed to gain further understanding. This technique is then used to design a Wi-Fi antenna. The second design uses a modified double-tuned matching network to create a single-band match for a planar monopole antenna. The matching network is implemented using a complementary-split-ring-resonator (CSRR). The design is once again analyzed using full-wave simulations and a circuit model is also developed. This technique is then applied to design a WiMax antenna. Both the Wi-Fi and WiMax antennas are fabricated and show good agreement between the simulated and measured results.

One goal of this thesis is to address several challenging compact antenna design issues by using transmission-line metamaterials. In particular, we demonstrate the design of a compact antenna with an extended bandwidth, multiband/multifunction compact/small antennas, and mutual-coupling reduction for two closely-spaced small antennas. The proposed compact transmission-line metamaterial antenna employs the concept of zeroth- index resonance and a wideband characteristic is enabled by detuning the resonance of each constituent metamaterial unit cell at a slightly different frequency, thus creating a multi-resonant return-loss passband. Furthermore, a single-cell transmission-line metamaterial loading scheme is applied to regular printed monopole antennas in order to introduce additional resonances at the low band and create multiband small antennas that meet the specifications for WiFi and WiMAX applications. Lastly, a simple ap- proach for reducing the mutual coupling in two closely-spaced small antennas is also presented, based on the idea of self-cancelation of the induced currents. The other important goal of this thesis is to develop volumetric negative-refractive- index transmission-line (NRI-TL) metamaterials. A volumetric NRI-TL slab is created by stacking 2D NRI transmission-line grids in the shunt-node configuration. This is done in a simple manner through images induced in a parallel-plate environment. Additional vias are strategically placed to suppress the parasitic parallel-plate mode. Moreover, multiconductor transmission-line theory is used to model the volumetric metamaterial slab. A fully-printed volumetric Veselago-Pendry transmission-line lens is designed and matched to free space. Using this proposed lens, it has been experimentally verified that the diffraction limit can be overcome.

One goal of this thesis is to address several challenging compact antenna design issues by using transmission-line metamaterials. In particular, we demonstrate the design of a compact antenna with an extended bandwidth, multiband/multifunction compact/small antennas, and mutual-coupling reduction for two closely-spaced small antennas. The proposed compact transmission-line metamaterial antenna employs the concept of zeroth- index resonance and a wideband characteristic is enabled by detuning the resonance of each constituent metamaterial unit cell at a slightly different frequency, thus creating a multi-resonant return-loss passband. Furthermore, a single-cell transmission-line metamaterial loading scheme is applied to regular printed monopole antennas in order to introduce additional resonances at the low band and create multiband small antennas that meet the specifications for WiFi and WiMAX applications. Lastly, a simple ap- proach for reducing the mutual coupling in two closely-spaced small antennas is also presented, based on the idea of self-cancelation of the induced currents. The other important goal of this thesis is to develop volumetric negative-refractive- index transmission-line (NRI-TL) metamaterials. A volumetric NRI-TL slab is created by stacking 2D NRI transmission-line grids in the shunt-node configuration. This is done in a simple manner through images induced in a parallel-plate environment. Additional vias are strategically placed to suppress the parasitic parallel-plate mode. Moreover, multiconductor transmission-line theory is used to model the volumetric metamaterial slab. A fully-printed volumetric Veselago-Pendry transmission-line lens is designed and matched to free space. Using this proposed lens, it has been experimentally verified that the diffraction limit can be overcome.

Metamaterials have experienced a rapid growth of interest over the past few years and new capabilities are being explored to broaden the range of their unique electromagnetic properties for functional devices, including tunable, switchable, and nonlinear properties. In the future, there is the prospect of opening even more exciting applications with metamaterials, not yet imagined and thought not to be possible with currently available techniques. In my dissertation, I discuss several solutions for passive and active metamaterials and metasurfaces, with a particular focus on their potential applications, enabling a new class of metamaterials in the spectral range from radio frequencies (RF) and microwaves, terahertz (THz) to visible light. First, I demonstrate that by loading plasmonic nanoantennas with nonlinear nanoparticles, the nonlinear optical processes, such as multiple wave mixing, high harmonic generation, phase conjugation and optical bistability may be realized at the nanoscale, thanks to the strongly enhanced optical near fields accompanied with the plasmonic resonance. I present here the design, practical realization, and homogenization theory of nonlinear optical metamaterials and metasurfaces formed by optical nanoantenna arrays loaded with nonlinearities. As an extreme case of light manipulation at the "atomic" scale, I also study the collective oscillation of massless Dirac fermions inside grapheme monolayers, in which surface plasmon polaritons are controlled by electrostatic gating. I present how a graphene monolayer may serve as a building block and design paradigm for adaptable, switchable and frequency-configurable THz metamaterials and nanodevices, realizing various functionalities for cloaking, sensing, absorbing, switching, modulating, phasing, filtering, impedance transformation, photomixing and frequency synthesis in the THz spectrum. Last I present various metamaterial designs applied to invisibility cloaks based on the scattering cancellation mechanism enabled by plasmonic materials and passive/active metamaterials and metasurfaces. This cloaking technology may be used for camouflaging, enhancing the sensitivity and signal-to-noise ratio in RF wireless communication and sensor networks. In addition, electrically-small antennas based on the phase compensation effect offered by metamaterials with low or negative material properties are presented, with tailorable modal frequencies, bandwidth, and radiation properties. / text

Tailoring surface plasmon (SP) resonances using metallic nanostructures for optical manipulation has been widely investigated in recent years; and there are many puzzles yet to be solved in this relatively new area. This thesis covers the study of the interaction of light with SP-supporting planar/patterned metallo-dielectric multilayer structures. Two separate, but closely related subjects were investigated using such structures, which are: SP-assisted optical transmission and optical metamaterials. The physical mechanisms of the SP-assisted transmission phenomenon were studied using planar/grating and planar/hole-array multilayer structures. Extraordinary light transmission has been demonstrated through experimental work and simulations for both arrangements; and the effects of different structural parameters on the transmission efficiencies of the structures were analyzed systematically. The interplays of the surface plasmon polaritons (SPPs) and localized surface plasmons (LSPs) in the extraordinary optical transmission (EOT) phenomenon were identified. The potential of the planar/hole-array multilayer structures as optical magnetic metamaterials was evaluated using two independent electromagnetic simulation techniques. The ability of such structures to produce strong magnetic resonances from infrared down to visible side of spectrum was revealed. The methods of tuning the magnetic response of the structures were suggested. A novel design of optical metamaterial based on high-order multipolar resonances in a single-layer plasmonic structure was also proposed. Numerical results from two different computation methods indicate that a simultaneously negative permittivity and permeability can be achieved in such a structure.

Developing materials that can conduct electricity easily, but block the motion of phonons is necessary in the applications of thermoelectric devices, which can generate electricity from temperature differences. In converse, a key requirement as chips get faster is to obtain better ways to dissipate heat. Controlling heat transfer in these crystalline materials devices — such as silicon — is important. The heat is actually the motion or vibration of atoms known as phonons. Finding ways to manipulate the behavior of phonons is crucial for both energy applications and the cooling of integrated circuits. A novel class of artificially periodic structured materials — phononic crystals — might make manipulation of thermal phonons possible. In many fields of physical sciences and engineering, acoustic wave propagation in solids attracts many researchers. Wave propagation phenomena can be analyzed by mathematically solving the acoustic wave equation. However, wave propagation in inhomogeneous media with various geometric structures is too complex to find an exact solution. Hence, the Finite Difference Time Domain method is developed to investigate these complicated problems. In this work, the Finite-Difference Time-Domain formula is derived from acoustic wave equations based on the Taylor’s expansion. The numerical dispersion and stability problems are analyzed. In addition, the convergence conditions of numerical acoustic wave are stated. Based on the periodicity of phononic crystal, the Bloch’s theorem is applied to fulfill the periodic boundary condition of the FDTD method. Then a wide-band input signal is used to excite various acoustic waves with different frequencies. In the beginning of the calculation process, the wave vector is chosen and fixed. By means of recording the displacement field and taking the Fourier transformation, we can obtain the eigenmodes from the resonance peaks of the spectrum and draw the dispersion relation curve of acoustic waves. With the large investment in silicon nanofabrication techniques, this makes tungsten/silicon phononic crystal a particularly attractive platform for manipulating thermal phonons. Phononic crystal makes use of the fundamental properties of waves to create band gap over which there can be no propagation of acoustic waves in the crystal. This crystal can be applied to deterministically manipulate the phonon dispersion curve affected by different crystal structures and to modify the phonon thermal conductivity accordingly. We can expect this unique metamaterial is a promising route to creating unprecedented thermal properties for highly-efficient energy harvesting and thermoelectric cooling.

Novel feedback signal interference concept for bandpass filter (BPF) design is proposed in this thesis. This new concept was utilized to design wide stopband BPF with superior performance for WLAN applications. The proposed filtering structure consists of two simple coupled-line couplers. The first coupler was employed within the main signal path and the second coupler which is open circuited at the opposite ends was used for the feedback circuit. This new filtering structure was fabricated using low temperature co-fired ceramic technology. The fabricated BPF exhibits an insertion loss (IL) of -1.3 dB with a 3dB fractional bandwidth of 13% at a centre frequency of 2.4 GHz. Furthermore, an attenuation level of -15 dB is achieved up to 4.7fo. Using stepped impedance coupled-lines in the feedback; the stopband performance of the proposed structure can be significantly improved while keeping passband performance intact. Furthermore, the feedback signal interference concept proved to be versatile and can be used to design high selectivity microstrip BPF using composite right/left handed transmission line unit cell in the feedback circuit. The measured results show that roll-up/down rate of more than 300 dB/GHz can be achieved with low IL.The spectrum based quality factor for CRLH TL based BPF is explored and thoroughly studied in this thesis to design a low phase noise oscillator. The proposed metamaterial BPF has higher spectrum based quality factor within the left-handed region due to the slow-wave propagation. This intriguing feature enables the design of a free-running oscillator with excellent phase noise performance operating at a frequency of 2.05 GHz. The fabricated oscillator demonstrates a phase noise of -126.7 dBc/Hz at 100 kHz frequency offset and a FOM of -207.2 dBc/Hz at a 1 MHz frequency offset, being one of the very best reported so far. Many microstrip multi-band BPF design techniques are presented in the literature that offers superior performance in terms of IL, 3dB FBW, and high selectivity. These methods mainly lack the ability to obtain high performance with compact size. Coupled slotted open stubs are used to design a miniaturized dual-wideband BPF. Interdigital capacitor and inner open stubs are used to improve rejection level within the stopbands and increase selectivity. The measurement results reveal that the fabricated dual-wideband BPF has two passbands with a 3dB FBW of 117% and 36%, at respective centre frequencies of 1 GHz and 6.65 GHz. The filter has a super compact size (0.09 Gammag × 0.05 Gammag) where Gammag denotes the guided wavelength at the centre frequency of the first passband and exhibits an attenuation level greater than 20 dB up to 12 GHz.

No description available.

The optical response of metallic structures is dominated by the dynamics of their free electron plasma. Plasmonics, the area of optics specializing in the electromagnetic behavior of heterogeneous structures with metallic inclusions, is undergoing rapid development, fueled in part by recent progress in experimental fabrication techniques and novel theoretical approaches. In this thesis I outline the behavior of four plasmonic material systems, and discuss the underlying physics that governs their optical response. First, the anomalous optical properties of solution-derived percolation films are explained using scaling theory. Second, a novel technique is developed to characterize the optics of amorphous nanolaminates, leading to the creation of a meta-material with anisotropic (hyperbolic) dispersion. The properties of such materials can be tuned by adjusting their composition. Third, the electrodynamics of vertically aligned multi-walled carbon nanotubes is derived through the development of a spectroscopic terahertz transmission ellipsometry algorithm. Lastly, a new diffraction based imaging structure based on metallic gratings is presented to have resolution capabilities which far outperform the diffraction limit. / Graduation date: 2013

<p>Metamaterials have gained extensive attention in recent years due to their ability to exhibit material properties otherwise difficult or impossible to obtain using natural materials. Nonlinear and active metamaterials in particular exhibit great promise for exploring new effects and applications, from tunability to mixing. However, nonlinear and active metamaterials have been explored significantly less than linear metamaterials to this point and much work has focused on the fundamental physics of nonlinear metamaterials. Our aim is to further extend the knowledge of practical nonlinear metamaterials and to demonstrate how they can be transformed to real-world applications through the use of embedded devices. In this dissertation, we demonstrate a variety of ways that devices can be embedded within metamaterial unit cells to provide nonlinear and active effects. </p><p>Chapter 1 introduces the basic theory of metamaterials, background of existing work, and the current limitations of nonlinear and active metamaterial design. In Chapter 2, we present the design, simulation, fabrication, and verification of an RF limiter metamaterial. We show how a metamaterial can be designed using RF engineering principles to act as an effective limiter in a new topology, relying on nonlinear devices embedded within a metamaterial. Chapter 3 shows our design and demonstration of a power harvesting metamaterial. We design a nonlinear metamaterial towards a potential application, discussing how the selection of an appropriate embedded device provides our desired functionality. In Chapter 4 we show how nonlinear and active metamaterials can be used to realize phase conjugation, including demonstration of negative refraction and imaging through the use of these metamaterials. We also discuss design approaches to moving these metamaterials towards real-world applications. Chapter 5 discusses our work concerning metamaterials based on transistors. First we show that appropriate design of a transistor circuit allows us to tune the quality factor and resonant frequency of a metamaterial. We use this metamaterial for time-varying mixing, as well, demonstrating a mixing metamaterial that remains linear. We then illustrate how using transistors as nonlinear devices provides much greater design freedom for use with metamaterials. We show that the nonlinearity of a metamaterial can be dramatically enhanced through the use of transistors and even dynamically tuned, applying these nonlinear metamaterials to applications including phase conjugation and acoustoelectromagnetic modulation. In Chapter 6 we summarize the achievements of the presented research and directions for future work that build on the work described in this thesis.</p> / Dissertation