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Novel broadband designs of patch antennas with an air substrate have been proposed in this dissertation. In the dual-frequency design, the study of single-fed dual-frequency microstrip antenna with a V-shaped slot has been first presented. As for the broadband patch antenna design, antennas with a U-shaped slot or a pair of wide slits can have an operating bandwidth more than 2.0 times that of a conventional one at a given operating frequency. The antenna bandwidth of then can be enhanced about 25%. In the designs of reducing cross-polarization, by using dual capacitive feeds with equal input powers, but with a 180¢X-phase shift, The cross-polarization radiation can be reduce about 10 to 15dB in the H-plane. Finally, A broadband shorted patch antenna fed by an aperture-coupled feed with an H-shaped coupling slot is proposed. By using an air substrate of thickness about 0.07 free-space wavelength of the center operating frequency, the proposed antenna can have an impedance bandwidth of about 26.2%. And the antenna design reduced the antenna size to be 40%~50%of the simple case.

Nuclear magnetic resonance (NMR) spectroscopy has been extensively used to investigate the structure and dynamics of host-guest systems. NMR spectroscopy has gained attention because of its high spectral information content for studies of molecules in the solid state and in solution. However, the main weakness of NMR is the inherent low detection sensitivity. Host-guest interactions are weak; therefore these interactions can be particularly difficult to study due to weak spectral response. NMR methods are currently the best solution for measuring these responses with atomic-scale precision. Improving upon these limitations is the main goal of this dissertation research using laser-polarized xenon, liquid crystals, and polarization exchange pulse sequences. The first five chapters review the basics of NMR spectroscopy that is used throughout this dissertation. Chapters one and two concern the fundamental elements of liquid-state and liquid-crystal NMR spectroscopy. The third chapter deals with the properties of organic thermotropic and lyotropic liquid crystals including the ZLI 1132 and PBLG. Chapter four presents the theoretical and experimental aspects of optical pumping laser-polarized xenon and properties of xenon. An overview of the dissertation research is described in chapter six. Chapter seven describes the procedures for synthesizing many of the cryptophanes used in the NMR experiments in this dissertation. The cryptophanes synthesized include cryptophane-A, cryptophane-223, and cryptophane-E as well as the water-soluble derivatives of each. The eighth and ninth chapters investigate the binding kinetics of hydrocarbon and hydrogen gases to cryptophane-111 in organic solutions. Chapter ten illustrates the utility of liquid crystalline-aligned cryptophanes (bis- and cryptophane-A) reintroducing dipolar couplings in solution. Chapter eleven describes the exploitation of the reintroduced dipolar coupling of the guest molecule to transfer the abundant 1H nuclear spin magnetization to the rare 13C spins to enhance NMR detection sensitivity using an adiabatic Hartmann-Hahn cross polarization pulse sequence. Chapter twelve describes cryptophanes of varying cavity size to probe the host-guest dynamic coupling (with chloroform as a guest ligand) aligned in PBLG. Finally, chapter thirteen introduces preliminary xenon @ cryptophanes aligned in liquid crystals to achieve intermolecular polarization transfer.

京都大学 / 新制・課程博士 / 博士(理学) / 甲第24871号 / 理博第4981号 / 新制||理||1711(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)准教授 武田 和行, 教授 堀毛 悟史, 教授 北川 宏 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

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The continuous advancement in wireless communications technology demands new approaches to improving the capacity of existing radio links. The high data throughput required can be achieved by the complete utilization of space, time and polarization diversities inherent in any propagation environment. Among the different propagation scenarios, the indoor channels represent a particularly challenging problem given the number and complexity of interactions between the transmitted signal and the environment. This dissertation explores the interrelation between propagation physics and space-time-polarization diversity based on a novel high resolution channel sounding and reconstruction technique. First, a method to reconstruct the indoor complex channel response based on a limited set of samples and the elimination of the interference using deconvolution techniques is presented. Then, the results for the joint angle-of-arrival, delay characterization and depolarization of electromagnetic waves are presented. Finally, a novel approach to using depolarized multipath signals to boost the receiver signal-to-noise performance is presented. The current study shows that full utilization of the diversities of channel novel wireless systems can be proposed with significant improvement in capacity.

The continuous advancement in wireless communications technology demands new approaches to improving the capacity of existing radio links. The high data throughput required can be achieved by the complete utilization of space, time and polarization diversities inherent in any propagation environment. Among the different propagation scenarios, the indoor channels represent a particularly challenging problem given the number and complexity of interactions between the transmitted signal and the environment. This dissertation explores the interrelation between propagation physics and space-time-polarization diversity based on a novel high resolution channel sounding and reconstruction technique. First, a method to reconstruct the indoor complex channel response based on a limited set of samples and the elimination of the interference using deconvolution techniques is presented. Then, the results for the joint angle-of-arrival, delay characterization and depolarization of electromagnetic waves are presented. Finally, a novel approach to using depolarized multipath signals to boost the receiver signal-to-noise performance is presented. The current study shows that full utilization of the diversities of channel novel wireless systems can be proposed with significant improvement in capacity.

Dipolar couplings are one of the major source of structural information. Due to their dependence on the distance between the nuclei and the angle of orientation of the dipolar vector with respect to the magnetic field, they provide significant insight into the geometry and topology of molecules. As the dipolar interactions are in general present in the solid phase of the compounds, solid state NMR experiments have gained significant popularity and is widely used. Separated Local Field NMR spectroscopy based on cross-polarization technique has been used to measure the heteronuclear dipolar couplings in solid state. However, the technique undergoes many experimental challenges and requires further development. This thesis is concerned mainly with the development of techniques to measure the dipolar couplings accurately in oriented molecules. In this regard, a method for fast data acquisition is also proposed. The first chapter briefly introduces the basics of NMR spectroscopy, methodologies applied for obtaining a high resolution NMR spectrum in the solid state. An introduction to liquid crystals is presented and the nature of NMR interaction in the liquid crystalline phases is described. In chapter-2, a new pulse scheme has been proposed that includes the X-nucleus polarization in the SLF experiments and is shown to provide better sensitivity and resolution. A quantitative analysis with simulation and experimental results are also presented. In chapter-3, the performance of various homonuclear decoupling pulse schemes incorporated into SLF experiments tested on oriented systems are compared. The proposed pulse schemes are shown to provide high resolution spectrum with accurate dipolar coupling measurement for natural abundant samples and for uniformly labeled compounds as well. Theoretical description with simulation and experimental results shown here are found to provide optimum results under several technical complications seen with respect to the conventional methods used for SLF experiments. Chapter-4, an attempt is made to reconstruct 2D J-resolved and 2D- SLF spectra from several 1D experimental data. This is achieved with the help of projection reconstruction method and is shown to provide high resolution 2D spectrum with saving of experimental time by an order of two. Chapter-5, high resolution spectra from SLF experiments under phase alternating pulses and using amplitude and time averaged nutation techniques are shown for accurate dipolar coupling measurement with a dramatic reduction in rf power. This is important as the use of low rf power leads to low sample heating and can be applied suitably for the study of liquid crystals and salty biomolecules. Chapter-6, attempts are made to characterize two novel thiophene based liquid crystals using both solution and solid state NMR spectroscopy. C-H dipolar couplings measured from SLF experiments are mainly used to find the order parameters and geometry of the molecules.