V disertační práci popisuji metodu syntézy dipólové anténní řady s definovanou schopností prostorové a spektrální filtrace. Díky prostorové filtraci se směr hlavního laloku a hodnota zisku mění v celém pracovním pásmu jen zanedbatelně. Díky spektrální filtraci je hodnota zisku v pracovním pásmu nejvyšší a mimo toto pásmo nejnižší. Abychom syntetizovali anténní řadu s předepsanými filtračními vlastnostmi, optimalizujeme amplitudy, fáze a rozměry prvků dipólové anténní řady. Abychom počáteční optimalizaci co nejvíce urychlili, předpokládáme při výpočtu hodnot kriteriálních funkcí idealizovanou anténní řadu. Jelikož optimalizace zahrnuje požadavky na směr hlavního laloku, zisk i impedanční přizpůsobení, využíváme k syntéze multi-kriteriální optimalizaci. Optimalizovaná anténní řada byla následně analyzována ve vlnovém simulátoru, aby byl ověřen výsledek syntézy. Syntetizovaná anténní řada byla vyrobena a experimentálně byly ověřeny její vlastnosti.

UHF bands because more penetration can be achieved at low frequencies. Consequently, large antennas are required, which limits their use for small airborne applications. This thesis explores various GPR antenna designs for a bi-static system that are at least operational from 225 MHz to 255 MHz and suitable for small airborne applications. The 3D electromagnetic simulation software Ansys high-frequency structure simulator (HFSS) was used to simulate various sizes of strip dipole, triangular bowtie, half elliptical bowtie, and elliptical bowtie antennas. Several physical models were constructed to validate the return loss simulation results. Additionally, simulation data is included for a wire dipole and a helical antenna. The helical antenna proved to be too large for small airborne application, so focus was placed on the dipole and bowtie designs. The performance of the dipole and bowtie antenna models are compared by size, weight, return loss (𝑆11), peak gain, and the transmit-to-receive isolation. Out of the fourteen simulated models, twelve meet the bandwidth requirement with an average weight of 0.23 lbs. It is found that the strip dipole exhibited wider bandwidth characteristics than the triangular, elliptical, and half elliptical bowtie models, while maintaining similar weight and size. The smallest strip dipole model is 50 mm x 528 mm x 1 mm, weighs 0.17 lbs, and is operational from 225 MHz to 283 MHz. Two strip dipole test antennas were fabricated and tested. Test results confirm the simulation predictions.

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The thesis is focused on the design of a measuring antenna for 1 – 6 GHz band. It deals with the types of log periodic antennas with the the detailed elaboration of log periodic dipole antennas (LPDA). One can find the description of their functions, maximum features and the possibilities to use the asymmetrical feeder. Also there is the procedure of LPDA design and the realization of the design itself including simulation in 4NEC2 programme. In the next part there is a planar LPDA realization with the microstrip-to-balanced stripline balun symmetrization. This design was simulated and tested within the frames of Zeland IE3D programme. The last part contains the measuring results of S parametres as well as beam characteristics of the planar version of LPDA.

This thesis describes design and experimental verification of three types of the wideband antenna Bow-tie antenna, Vivaldi antenna and Spiral antenna. The tracked parameters are bandwidth, input impedance, gain and directivity patterns. Next step is design of millimeter-wave horn antennas. Attention is turned to the proper construction of a wideband feeder of the horn. For the final antenna structure, a bow-tie dipole and a Vivaldi antenna were chosen. The antenna construction is aimed to provide a wide bandwidth on one hand and a high gain on the other hand.

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.