The thesis is focused at the design and the execution of a dual-port microstrip circularly-polarized antenna for the frequency of 2.4 GHz. The first part describes general knowledge about microstrip antennas, circularly-polarized, options of power supply, used medium etc. The second part of the thesis deals with the design and simulation of antennas with the use of software called CST Microwave Studio and Zeland IE3D. In the last part, confrontation of simulation and measurement results is provided.

We are developing a tabletop extreme-ultraviolet source using high harmonic generation at Brigham Young University. The thesis goes over the theory of high harmonic generation using the three-step model. This tabletop source was designed for probing magnetic domains of iron nanoparticles. We present optimization of the 42 eV and 52 eV harmonics through phase matching. Phase matching consists of tuning the intensity of the IR beam and pressure of the gas medium. The target gas medium used for this thesis is argon. The 42 eV harmonic was optimized to 8.2 billion photons per second. This was used with a 1500 mm focal-length lens, 15 mm medium length, laser power of 1.53 Watts, and a pressure of 12 Torr of argon gas. The 52 eV harmonic was optimized to 1.5 billion photons per second with a 1500 mm focal-length lens, 20 mm medium length, laser power of 3.29 W, and 14.9 Torr of argon gas. There are two designs for selection of harmonics: 1) a tunable design consisting of a toroidal mirror and flat diffraction grating and 2) a set of normal-incidence extreme-ultraviolet mirrors designed for 42 or 52 eV photons. Magnetic imaging uses x-ray magnetic circular dichroism to obtain magnetic contrast and use it to visualize magnetic nanosystems. Therefore, the high harmonic source also needs to generate circularly polarized light. Generating circularly polarized high harmonics is possible with a bichromatic beam. This is achieved using an apparatus called the MAZEL-TOV designed by Oren Cohen’s group at Technion University in Israel. The MAZEL-TOV consists of a BBO crystal for second harmonic generation, a pair of pulse delay compensation plates, and a quarter-wave plate. These optics are placed inline with the laser beam. We have successfully optimized the circularly polarized extreme-ultraviolet harmonics with the MAZEL-TOV. A spectrometer was made to calibrate the harmonics in the MAZEL-TOV spectrum. The tabletop source was then used to demonstrated coherent diffraction imaging of two pinholes.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19406号 / 工博第4122号 / 新制||工||1635(附属図書館) / 32431 / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 中條 善樹, 教授 澤本 光男, 教授 赤木 和夫 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Dual-band antenna elements that support dual-polarization provide ideal performance for applications including space-based platforms, multifunction radar, wireless communications, and personal electronic devices. In many communications and radar applications, a dual-band, dual-polarization antenna array becomes a requirement in order to produce an electronically steerable, directional beam capable of supporting multiple functions. The multiple polarizations and frequency bands allow the array to generate multiple simultaneous beams to support true multifunction radar. Many of the applications in spaced-based systems and personal electronic devices have strict restraints on the size and weight of the antenna element, favoring a low-profile, lightweight device. The research performed in this dissertation focuses on the design of a dual-band, dual-polarized antenna element capable of operating as an isolated element or in an array environment. The element contains two concentric, dual-polarized radiators. The low band radiator is a shorted square ring antenna, and the high band radiator is a square ring slot. Each constituent element achieves circular polarization through the introduction of triangular perturbations into opposing corners of the radiating element. This technique has been shown to introduce two, near-degenerate modes in the structure that – when excited in phase quadrature – combine to form circular polarization. The perturbations allow circular polarized operation with only a single feed point. The sense of the circular polarization is determined by the location of the feed point with respect to the perturbations. Both senses of circular polarization are excited by the introduction of orthogonal feeds for each of the two radiating elements. Thus, dual-ban, dual-circular polarization is obtained. The element achieves a low-profile from its printed circuit board realization. The high band square ring slot is realized in stripline. The orthogonal feeding transmission lines are printed on opposing sides of an electrically thin dielectric layer to allow them to cross without physically intersecting. This thin feeding substrate is sandwiched between two dielectric layers of matched dielectric constant. A ground plane is located on the top and bottom of the sandwiched dielectric structure, and the top ground plane contains the square ring slot with perturbed corners. Slotted stripline structures have been shown in the literature to excite a parallel-plate mode that can degrade overall performance of the antenna. Plated through holes are introduced at the outer perimeter of the square ring slot to short out this parallel-plate mode. The plated through holes (also called vias) serve as the shorting mechanism for the low band microstrip shorted square ring radiator. This element also contains triangular perturbations at opposing corners to excite circular polarization with a single feed point. In this element, orthogonal probe feeds are present to excite both senses of circular polarization. A dual-band, dual-polarized antenna element was built, tested, and compared to simulations. The constructed element operated at two distinct industrial, scientific, and medical (ISM) frequency bands due to their popularity in low power communications. The antenna element was realized in a multilayer printed circuit layout. A complex design procedure was developed and submitted to a printed circuit board company who manufactured the antenna element. The s-parameters of the antenna were measured using a Network Analyzer, and the results show good agreement with simulations. The radiation and polarization characteristics were measured in a compact range facility. These results also agreed well with simulations. The measured results verify the simulation models that were used in the simulations and establish a confidence level in the feasibility of constructing this element. The dual-band, dual-polarization nature of this element was established through the construction and measurement of this element. A novel size reduction technique was developed that allows for significant reduction of the element's footprint. This size reduction facilitates the placement of this element within an array environment. The loading technique utilizes a structure analogous to a parallel-plate capacitor to drastically reduce the overall size of the low frequency shorted square ring. The loading structure uses a substrate that is separate from that of the radiating elements. This allows the load to use a high dielectric material to achieve a high capacitance without requiring the radiating elements to be printed on high dielectric material that is potentially expensive and lossy at microwave frequencies. The two frequency bands were selected to be in separate industrial, scientific, and medical (ISM) bands. These frequency bands are increasingly popular in low power communication devices because unlicensed operation is permitted. The 2.45 GHz and 5.8 GHz ISM bands are commonly used for applications including Bluetooth technology, multiple 801.11 protocol, cellular phone technology, and cordless phones. The ISM bands were chosen for this antenna element due to their popularity, but this antenna is not restricted to these bands. The frequency ratio can be altered by controlling the dielectric constant used in the printed circuit board design, the parameters of the capacitive loading structure, and the size of the constituent elements that are used. After the size reduction technique is applied, the dual-band, dual-polarized elements can be placed in an array environment resulting in an array capable of generating both senses of circular polarization in the two, distinct ISM bands. This provides an aperture capable of supporting multiple functions. Depending on the applications required, the frequency bands of the antenna element can be altered to suit the particular system needs. The array analysis performed in this dissertation used a unique hybrid calculation technique that utilizes nine active element patterns to represent the patterns of the individual elements within a large antenna array. A common first look at array performance is achieved by multiplying the element pattern of an isolated element by an array factor containing the contributions of the geometrical arrangement of the antenna elements. This technique neglects mutual coupling between elements in the array that can alter the impedance match and radiation characteristics of the elements in the array. The active element pattern defines the radiation pattern of a given element in an array when all other elements are terminated in a matched impedance load. The active element pattern is unique for each element in an array. When these patterns are summed, the exact array pattern is obtained. While this technique has the advantage of accuracy, it is not ideal because it requires the simulation, calculation, or measurement of the pattern for each element in the array environment. The technique developed in this dissertation uses only nine active element patterns. These elements are then assigned to represent the active element patterns for all elements in the array depending on the geometrical region where the given element resides. This technique provides a compromise between the speed of using a single element pattern and the accuracy of using the unique active element pattern for each element in the array. The application of these two concentric, coplanar radiators along with the capacitive loading technique provides a unique contribution to the field of antenna engineering. The majority of dual-band antenna elements in the literature operate with a single polarization in each band. The ones that operate with dual-polarization in each band are typically limited to dual-linear polarization. Circular polarization is preferable to linear in many applications because it allows flexible orientation between the transmitting antenna and receiving antenna in a communications system, while also mitigating multipath effects that lead to signal fading. The ability to operate with two, orthogonal senses of circular polarization allows a system to reuse frequencies and double system capacity without requiring additional bandwidth. The uniqueness of this element lies in its ability to provide dual-circular polarization in two separate frequency bands for an individual element or an antenna array environment. The arrangement of the two element geometries with the addition of the novel capacitive loading technique is also unique. The performance of this element is achieved while maintaining the light weight, low profile design that is critical for many wireless communications applications. This dissertation provides a detailed description of the operation of this dual-band, dual-polarized antenna element. The design of the constituent elements is discussed for several polarization configurations to establish an understanding of the building blocks for this element. The dual-band, dual-polarized element is presented in detail to show the impedance match, isolation, and axial ratio performance. The capacitive loading technique is applied to the dual-band, dual-polarized element, and the performance with the loading in place is compared to the performance of the unloaded element. Next, there is an in-depth description of the array calculation technique that was developed to incorporate mutual coupling effects into the array calculations. This technique is then applied to the dual-band, dual-polarized array to show the performance of several array sizes. / Ph. D.

La chiralité est une propriété essentielle des molécules naturelles, intervenant dans de nombreux mécanismes biologiques du vivant. Elle peut être caractérisée grâce à l’activité chiroptique des molécules chirales, à travers le dichroïsme circulaire, le pouvoir rotatoire, la dispersion rotatoire optique ou encore la luminescence polarisée circulairement. Les molécules biaryles et hélicéniques possèdent des propriétés chiroptiques intenses et sont des molécules de choix pour leurs applications dans de nombreux domaines, de la catalyse à l’optoélectronique.Les travaux réalisés au cours de cette thèse traitent de la synthèse de nouvelles molécules biaryles et hélicénoïdes et de l’étude de leurs propriétés spectroscopiques en interaction avec leur environnement. Dans un premier temps, nous avons effectué la synthèse de différentes familles de molécules à géométrie hélicoïdale possédant des systèmes aromatiques étendus. Afin de cibler des applications biologiques, nous avons également mis au point leur hydrosolubilisation par introduction de chaînes PEG. Dans un deuxième temps, nous nous sommes consacrés à l’étude de leurs propriétés spectroscopiques et en particulier chiroptiques en fonction de leur structure et de la dépendance de ces propriétés en présence de protons, de métaux ou d’acide désoxyribonucléique (ADN). Au cours de cette étude, une réaction photochimique inattendue a permis d’obtenir un produit photogénéré inédit présentant des interactions sélectives avec des ADN G-quadruplexes. Enfin, afin d’exploiter la modularité contrôlée des propriétés chiroptiques, nous avons travaillé sur un projet de conception de nouvelles molécules chirales pouvant détecter sélectivement les sucres en modifiant le squelette de ces molécules avec des acides boroniques. / Chirality is an essential property of natural molecules, involved in many living biological mechanisms. It can be characterized by the chiroptical activity of chiral molecules, through circular dichroism, rotatory power, optical rotatory dispersion or circularly polarized luminescence. Biaryl and helicenic molecules are known for their intense chiroptical properties and they can be used for their applications in many fields, going from catalysis to optoelectronics.The research carried out during this thesis deals with the synthesis of new biaryl and helicenoid molecules and the study of their spectroscopic properties in interaction with their environment. First, different families of helicoidal molecules with extended aromatic systems have been synthesized. In order to target biological applications, their hydrosolubilization was achieved by the addition of PEG chain. Then, we focused on their spectroscopic and especially chiroptical properties and their modulation according to their structures, their interaction with protons, metals or deoxyribonucleix acid (DNA). During these studies, we experienced an unexpected photochemical reaction, which lead to a new photogenerated product revealing selective interactions with DNA G-quadruplexes. Finally, in order to exploit the controlled modularity of chiroptical properties, new chiral molecules that selectively detecting sugars by with boronic acids have been designed.

In this study we tried to design a microstrip antenna, to get a suitable radiation pattern for a LEO satellite. Our aim is to get a radiation pattern that has a maximum power which is not in the broadside direction to the antenna surface / instead broadside radiation has a relatively lower power density. Maximum power radiation is desired to be at about 30 &ndash / 50 degrees angle beyond the normal to the antenna surface. We desire circularly polarized radiation. We used two concentric antennas / one is a circular patch at the center and the other is an annular ring which is used at the outer region. By using Ansoft Ensemble 8.0 software, we design an antenna which has a resonance frequency at 8.2 GHz. Using the result of the program we design the real antenna. The measurement results are compared with the simulation results.

This work focuses on the design circularly polarized serial antennas array operate in the ISM band (5.725 GHz to 5.875 GHz). Design of antennas is divided into three parts. In the first part is designed feeding system, followed by two types of circularly polarized antennas and at the last point, these components are integrated. Furthermore, these antennas are fabricated, measured their parameters and used for experimental verification of the influence of multipath transmission in-vehicle.

This thesis discusses Slot antennas that are based in gap waveguide technology, which allows them to work with high frequency signals. It contains theoretical findings about antennas and waveguides, which are later used in the design. The practical section of this thesis concentrates on designing a specific gap waveguide for 10 and 24 GHz frequencies, starting with modeling and parameter optimalization. This gap waveguide is then used as a base for slot antenna design. The final antenna is designed for frequency of 10 GHz, for both linear and right-handed circular polarizations. With right-handed circular polarization, the achieved band was approximately 1.41 GHz, while the gain was 7,6 dB.

Le dichroïsme circulaire de photoélectrons (PECD) se manifeste par une intense asymétrie avant/arrière dans la distribution angulaire de photoélectrons selon l’axe des photons, lors de la photoionisation d’un énantiomère pur de molécule chirale en phase gazeuse par un rayonnement polarisé circulairement. Cette thèse est consacrée à l’étude de ce phénomène, avec le synchrotron de la ligne DESIRS, sur différents systèmes chiraux allant de molécules libres (composés bromés, alanine) aux agrégats de glycidol et aux complexes formés avec l’eau. Pour ce faire, des mesures expérimentales menées à l’aide du spectromètre double imageur à coïncidence électron/ion DELICIOUS 3 ont été couplées à des calculs théoriques (CMS-Xα). Le chapitre 1 introduit les concepts fondamentaux nécessaires à l’étude de la chiralité en physique et le chapitre 2 présente les méthodes expérimentales et théoriques mises en œuvre. Le chapitre 3 détaille les résultats obtenus sur des composés chiraux halogénés : l’acide bromo-propionique (BPA) et les isomères 1,3- et 1,4-bromo-phényléthylamine (BrPhEtA). La sensibilité du PECD à l’isomérie, de même que le rôle de la localisation de l’orbitale initiale par rapport au centre chiral sont au cœur de cette étude. Le PECD du plus simple acide aminé chiral protéique, l’alanine, produit par chauffage résistif et par thermo-désorption d’aérosol, est présenté au chapitre 4 avec une étude conformationnelle selon la température conduisant à une distribution plausible des conformères. Ces résultats sont ensuite discutés dans le contexte de l’homochiralité de la vie (i.e. le fait que les acides aminés sont tous de type L dans la biosphère), le PECD étant un processus photophysique asymétrique pouvant induire un enrichissement énantiomérique. Le chapitre 5 s’intéresse au PECD sur des systèmes plus complexes : les agrégats de glycidol et les complexes de glycidol et d’eau. Une simple sélection en masse permet de mettre en évidence un effet spectaculaire de l’agrégation sur le PECD observé. DELICIOUS 3 permet ensuite d’éliminer des processus en cascade par une sélection en taille des neutres natifs. / Photoelectron Circular Dichroism (PECD) is observed as a forward/backward asymmetry, with respect to the photon axis, of the photoelectron angular distributions resulting from the circularly polarized light-induced photoionization of gas phase pure enantiomers of chiral species. This thesis is devoted to the study, with the synchrotron of the DESIRS beamline, of this phenomenon on different chiral systems from free molecules (bromine compounds, alanine) to glycidol clusters and water-glycidol complexes. Chapter 1 introduces the fundamental concepts required for the study of chirality in physics and chapter 2 presents the experimental and theoretical methods which have been used. Chapter 3 gives details concerning the results on the halogenated chiral compounds: bromopropionic acid (BPA) and 1,3- and 1,4-bromo-phenylethylamine isomers (BrPhEtA). The sensitivity of PECD to isomerism as well as the role of the localization of the initial orbital of the outgoing electron with respect to the chiral center is at the core of this study. The PECD of the simplest proteic chiral amino acid, alanine, produced by resistive heating and thermodesorption of an aerosol, is introduced in chapter 4 with a conformational study depending on temperature, leading to a plausible conformer distribution. These results are then discussed in the context of homochirality of life (i.e. the fact that only L-amino acids are found in the biosphere) as PECD is an asymmetric photophysical processes which can induce an enantiomeric enrichment. Chapter 5 is focused on PECD in systems of greater complexity: glycidol clusters and water-glycidol complexes. A simple mass selection enables to unravel a spectacular clustering effect on the observed PECD and the use of DELICIOUS 3 enables then to remove any cascading processes thanks to a size selection of nascent species.

The thesis is focused on the research of THz antenna arrays to be used for communications. Attention is turned to modeling metallic surfaces at THz frequencies, a proper characterization of gold conductivity, its relation to Drude model and corresponding measurements. Moreover, the best methods for modeling thin metallic layers (depending on the skin depth related to the metal thickness) are presented. An optimized element of a THz 2×2 antenna array designed for the application of communications is developed in a way that enables an expansion to a larger array. The expansion ability is demonstrated on a 4×4 antenna array which is presented in the thesis too. The designed antennas achieve parameters better than the state-of-art antennas. The presented antennas radiate circularly polarized wave at THz frequencies, operate in a wide bandwidth, have a high gain and are of a compact size. In the thesis, an 8×8 antenna array with a beam steering capability is presented. The main beam of the antenna array can be controlled in two dimensions. A high gain of the radiated circularly-polarized wave can be achieved that way. Different approaches to modeling antennas with thin metallic layers are compared and the best methods are recommended from the viewpoint of different requirements. The designed 2×2 and 4×4 antenna arrays are manufactured using a microfabrication technology. Each step of the fabrication is described in detail and discussed. The reflection coefficient at the input of antennas is measured and compared with simulations. Discrepancies in results are associated with surface roughness which is analyzed by a scanning probe microscope and a scanning electron microscope. By down-scaling the developed THz antenna, a low-profile high-gain antenna for Ka-band space applications is designed. The presented antenna achieves better results than state-of-art CubeSat antennas. The antenna performance is verified by a prototype to be operated at 9 GHz, and the radiation characteristics are experimentally confirmed.