In the last decade, design and application of negative materials have been one of the most interesting subjects in the electromagnetic research. The extraordinary properties of double negative (DNG) and single negative (SNG) materials have been studied extensively over this period. In this thesis, one of the unusual properties of negative materials, the evanescent amplification, is used to improve the sensitivity of the near field probes. The effect of placing DNG and SNG layers between the near field probes and the targets are investigated theoretically. A sensitivity definition is introduced for evanescent probes and it is shown using quantitative measures that the sensitivity can be increased using DNG and SNG materials for a target in vacuum and for a buried target. The electromagnetic loss of the negative materials and the mismatch between the material properties of the host medium and DNG and SNG materials are studied. Using an unmatched DNG layer or SNG layer enhances the sensitivity within an evanescent spectrum range while a lossless and matched DNG layer improves the sensitivity of entire evanescent spectrum. The idea of using negative materials is implemented over conventional near field probes by numerical experiments. Sensitivities of open-ended waveguides and open-ended coaxial lines for a specific application are studied in the presence of negative materials. In the case of precursor pitting detection on airplane bodies, the sensitivity of an open-ended waveguide probe is increased by 35 times for a λ/10 sized cubic crack. It is also shown that the negative material increases the quality of the image generated by the probe. The sensitivity improvement is also verified for an open-ended coaxial line. A 11 times improvement is achieved for a similar detection practice, with a λ/20 sized crack. The effect of coaxial line size and the dielectric material on the sensitivity enhancement are studied. The improvement is studied theoretically and numerically for an electrically small dipole. Theoretical studies show that when a small dipole is placed within a spherical shell made of DNG materials, the antenna parameters of the dipole becomes more sensitive to the position of a target placed outside the negative material shell. The field distribution generated by a small dipole in a multilayered spherical medium is studied for this purpose. Numerical analysis of a small dipole placed next to a planar DNG layer is presented. The DNG layer increases the sensitivity of the dipole due to a λ/30 sized metallic target by 5.5 times. To provide experimental verification, the sensitivity of an electrically small loop is studied. SNG materials with a negative permeability around 1.25 GHz are designed using modified split ring resonators (MSRR). By using the effective parameters of the designed structure, a sensitivity improvement of 10 times is achieved numerically. The improvement is verified using fabricated MSRR structures. The sensitivity of the small loop is enhanced by 9 times for a λ/12.2 sized metallic target. The sensitivity improvements are achieved within the frequency band where the MSRR structures behave as a μ-negative SNG material.

In the last decade, design and application of negative materials have been one of the most interesting subjects in the electromagnetic research. The extraordinary properties of double negative (DNG) and single negative (SNG) materials have been studied extensively over this period. In this thesis, one of the unusual properties of negative materials, the evanescent amplification, is used to improve the sensitivity of the near field probes. The effect of placing DNG and SNG layers between the near field probes and the targets are investigated theoretically. A sensitivity definition is introduced for evanescent probes and it is shown using quantitative measures that the sensitivity can be increased using DNG and SNG materials for a target in vacuum and for a buried target. The electromagnetic loss of the negative materials and the mismatch between the material properties of the host medium and DNG and SNG materials are studied. Using an unmatched DNG layer or SNG layer enhances the sensitivity within an evanescent spectrum range while a lossless and matched DNG layer improves the sensitivity of entire evanescent spectrum. The idea of using negative materials is implemented over conventional near field probes by numerical experiments. Sensitivities of open-ended waveguides and open-ended coaxial lines for a specific application are studied in the presence of negative materials. In the case of precursor pitting detection on airplane bodies, the sensitivity of an open-ended waveguide probe is increased by 35 times for a λ/10 sized cubic crack. It is also shown that the negative material increases the quality of the image generated by the probe. The sensitivity improvement is also verified for an open-ended coaxial line. A 11 times improvement is achieved for a similar detection practice, with a λ/20 sized crack. The effect of coaxial line size and the dielectric material on the sensitivity enhancement are studied. The improvement is studied theoretically and numerically for an electrically small dipole. Theoretical studies show that when a small dipole is placed within a spherical shell made of DNG materials, the antenna parameters of the dipole becomes more sensitive to the position of a target placed outside the negative material shell. The field distribution generated by a small dipole in a multilayered spherical medium is studied for this purpose. Numerical analysis of a small dipole placed next to a planar DNG layer is presented. The DNG layer increases the sensitivity of the dipole due to a λ/30 sized metallic target by 5.5 times. To provide experimental verification, the sensitivity of an electrically small loop is studied. SNG materials with a negative permeability around 1.25 GHz are designed using modified split ring resonators (MSRR). By using the effective parameters of the designed structure, a sensitivity improvement of 10 times is achieved numerically. The improvement is verified using fabricated MSRR structures. The sensitivity of the small loop is enhanced by 9 times for a λ/12.2 sized metallic target. The sensitivity improvements are achieved within the frequency band where the MSRR structures behave as a μ-negative SNG material.

In this work, waveguides with simultaneous negative dielectric permittivity and magnetic permeability, otherwise known as left-handed waveguides, are investigated. An approach of formulating and solving an eigenvalue problem with finite element method resulting in the dispersion relation of the waveguides is adopted in the analysis. Detailed methodology of one-dimensional scalar and two-dimensional vector finite element formulation for the analysis of grounded slab and arbitrary shaped waveguides is presented. Based on the analysis, for waveguides with conventional media, excellent agreement of results is observed between the finite element approach and the traditional approach. The method is then applied to analyze left-handed waveguides and anomalous dispersion of modes is found. The discontinuity structure of a left-handed waveguide sandwiched between two conventional dielectric slab waveguides is analyzed using mode matching technique and the results are discussed based on the inherent nature of the materials. The scattering characteristics of a parallel plate waveguide partially filled with left-handed and conventional media are also analyzed using finite element method with eigenfunction expansion technique.

Le travail de cette thèse est en rapport avec les métamatériaux et ses applications. Tout d’abord, un état de l’art est dressé en présentant leur évolution depuis leur apparition en 19ème siècle jusqu’au nos jours. Les notions sur les milieux chirale, bi-anisotrope, cristaux photoniques et quelques applications dans ces milieux sont données. Ensuite, nous présentons les équations classiques de Maxwell dans les milieux complexes. L’effet bi-anisotrope dans les métamatériaux est ensuite validé par l’extraction des paramètres caractéristiques du matériau main gauche (LHM). La validation a été faite en utilisant deux types différents du résonateur avec inclusion (SRR). Les métamatériaux sont également étudiés comme des cristaux photoniques quand les dimensions utilisées sont de l’ordre de la longueur d’onde correspondant.De plus, les résonateurs SRR et multi-SRR sont analysés du point de vue analytique et électromagnétique afin d’extraire leur fréquence de résonance. Par conséquent, ces composants peuvent être introduits dans différents types de conception; La surface conductrice magnétique artificielle (AMC) illustre un cas explicite et efficace de ces derniers. Une antenne dipôle, placée sur cette surface à la place d’un plan de masse conventionnel, a été étudiée comme une application des métamatériaux. Les résultats relatifs sur la directivité, le gain et le coefficient de réflexion montrent une nette amélioration. Une antenne multi-bandes, comme une autre application des métamatériaux, a également été conçue et simulée. Le résonateur SRR est inséré dans l’antenne de départ afin de créer une autre résonance, et par conséquent une autre bande est ainsi créée. / The work in this thesis deals with metamaterials, its components and applications. A historical overview about these materials, features and researches in the domain are presented. Chiral media, binaisotropic materials and photonic crystals are also studied in order to visualize physics behind metamaterials.Electromagnetic properties in complex media are widely investigated. Starting from Maxwell’s equations, bi-anisotropic materials and their effect are deeply analyzed whereas two types of Split Ring Resonator (SRR) are treated to determine constitutive parameters of Left Handed Materials (LHM). The metamaterials are also studied as photonic crystals since the effective medium approach is not applicable when the dimensions of the inclusions tend to the operating wavelength.Moreover, SRRs and Multi SRRs are synthesized analytically and electromagnetically in order to extract their resonant frequencies. Consequently, these components could be introduced in any design; Artificial Magnetic Conductor (AMC) surface is an efficient case. Thus, a low profile antenna positioned over such surface is examined as an application of metamaterials. The results of directivity, gain and reflection coefficient are of great importance and affirm the employing of metamaterials in such applications. A dual band PCB antenna, as another application of metamaterials, is designed and simulated. The SRR element studied in the previous chapters is used as the trap which inserted in the arm of the antenna in order to create another resonance, and consequently another band is created.