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University, Diss., 2004--Karlsruhe. / Download lizenzpflichtig.

Yes / An offset quad-element, two-port, high-gain, and multiband multiple-input multiple-output (MIMO) planar antenna based on a log-periodic dipole array (LPDA) for Ku/K-band wireless communications is proposed, in this paper. A single element antenna has been designed starting from Carrel's theory and then optimized with a 50-Ω microstrip feed-line with two orthogonal branches that results mainly in a broadside radiation pattern and improves diversity parameters. For experimental confirmation, the designed structure is printed on an RT-5880 substrate with a thickness of 1.57 mm. The total substrate dimensions of the MIMO antenna are 55 × 45 mm2. According to the measured results, the designed structure is capable of working at 1.3% (12.82-12.98 GHz), 3.1% (13.54-13.96 GHz), 2.3% (14.81-15.15 GHz), 4.5% (17.7-18.52 GHz), and 4.6% (21.1-22.1 GHz) frequency bands. Additionally, the proposed MIMO antenna attains a peak gain of 4.2-10.7 dBi with maximum element isolation of 23.5 dB, without the use of any decoupling structure. Furthermore, the analysis of MIMO performance metrics such as the envelope correlation coefficient (ECC) and mean effective gain (MEG) validates good characteristics, and field correlation performance over the operating band. The proposed design is an appropriate option for multiband MIMO applications for various wireless systems in Ku/K-bands.

A hidroxiapatita e o esmalte dental são, na atualidade, alguns dos materiais mais pesquisados pela técnica de espectroscopia por Ressonância Paramagnética Eletrônica ? RPE. O esmalte dental, que possui cerca de 97% de sua massa constituída por cristais de hidroxiapatita, se apresenta como o tecido humano preferencial para dosimetria de radiação com o uso desta técnica, principalmente no caso de exposições acidentais da população em geral. A análise de hidroxiapatitas sintéticas tem por finalidade auxiliar o entendimento do espectro do esmalte dental bem como desenvolver um dosímetro de radiação com boa eficiência e eficácia. O espectrômetro em banda-K utiliza uma freqüência intermediária aos espectrômetros em banda-X e em banda-Q, possuindo uma melhor resolução que banda-X sem as dificuldades, devido à alta sensibilidade, do banda-Q. O presente trabalho tem como objetivo analisar espectros em banda-K de um bloco de esmalte irradiado e de hidroxiapatitas sintéticas, comparando com espectros de banda-Q e banda-X presentes na literatura, e ainda verificar a possibilidade de se fazer dosimetria de radiação com o uso deste aparelho. / Hydroxyapatite and tooth enamel are, nowadays, some of materials mostly investigated by the spectroscopic technique of Electron Paramagnetic Resonance ? EPR. Tooth enamel, that have about of 97% of its mass constituted by hydroxyapatite crystals, appears itself as the preferential human tissue for radiation dosimetry using EPR, mainly in case of accidental expositions by ordinary personnel. The analyses of synthetic hydroxyapatites have as the main goal to help the understanding of tooth enamel?s spectrum seeking the developing of a radiation dosimeter with good efficiency and accuracy. The K-band EPR spectrometer uses an intermediate frequency between the spectrometers in X-band and Q-band, possessing a better resolution than the X-band without presenting the Q-band?s difficulties. In this preliminary work the EPR spectra of a small block tooth enamel and synthetic hydroxyapatites irradiated were analyzed in K-band, comparing the results with X- and Q-band with published results, the possibility of performing radiation dosimetry at K-band was verified.

A K-band integrated super-regenerative amplifier (SRA) in a 130nm SiGe BiCMOS technology is designed and characterized. The circuit is based on a novel stacked transistor differential cross-coupled oscillator topology, with a controllable tail current for quenching the oscillations. The fabricated integrated circuit (IC) occupies an area of 0.63mm2, and operates at the free-running center frequency of 25.3 GHz. Characterization results show circuit operation from a minimum input power level required for a phase coherent output as −110 dBm, and the input power level corresponding to the linear to logarithmic mode transition of −85 dBm, the lowest reported for K-band integrated logarithmic mode SRAs to date to the knowledge of the authors. The measured output power is 7.8dBm into a 100 differential load. The power consumption of the circuit is 110mW with no quench signal applied, and 38mW with 30 % duty cycle quenching. The quench waveform designed for the reported measurement result is also discussed.

A hidroxiapatita e o esmalte dental são, na atualidade, alguns dos materiais mais pesquisados pela técnica de espectroscopia por Ressonância Paramagnética Eletrônica ? RPE. O esmalte dental, que possui cerca de 97% de sua massa constituída por cristais de hidroxiapatita, se apresenta como o tecido humano preferencial para dosimetria de radiação com o uso desta técnica, principalmente no caso de exposições acidentais da população em geral. A análise de hidroxiapatitas sintéticas tem por finalidade auxiliar o entendimento do espectro do esmalte dental bem como desenvolver um dosímetro de radiação com boa eficiência e eficácia. O espectrômetro em banda-K utiliza uma freqüência intermediária aos espectrômetros em banda-X e em banda-Q, possuindo uma melhor resolução que banda-X sem as dificuldades, devido à alta sensibilidade, do banda-Q. O presente trabalho tem como objetivo analisar espectros em banda-K de um bloco de esmalte irradiado e de hidroxiapatitas sintéticas, comparando com espectros de banda-Q e banda-X presentes na literatura, e ainda verificar a possibilidade de se fazer dosimetria de radiação com o uso deste aparelho. / Hydroxyapatite and tooth enamel are, nowadays, some of materials mostly investigated by the spectroscopic technique of Electron Paramagnetic Resonance ? EPR. Tooth enamel, that have about of 97% of its mass constituted by hydroxyapatite crystals, appears itself as the preferential human tissue for radiation dosimetry using EPR, mainly in case of accidental expositions by ordinary personnel. The analyses of synthetic hydroxyapatites have as the main goal to help the understanding of tooth enamel?s spectrum seeking the developing of a radiation dosimeter with good efficiency and accuracy. The K-band EPR spectrometer uses an intermediate frequency between the spectrometers in X-band and Q-band, possessing a better resolution than the X-band without presenting the Q-band?s difficulties. In this preliminary work the EPR spectra of a small block tooth enamel and synthetic hydroxyapatites irradiated were analyzed in K-band, comparing the results with X- and Q-band with published results, the possibility of performing radiation dosimetry at K-band was verified.

[pt] Neste trabalho, é abordado um estudo para o desenvolvimento de filtros passa faixa cuja função de transferência é denominada quase-elíptica ou semielíptica. Esse nome vem por causa da sua principal característica que é a de apresentar apenas um par de polos de atenuação na banda de rejeição. O par de polos é determinado por meio do acoplamento cruzado entre dois pares de ressonadores dispostos de forma não adjacente, dessa maneira, enquanto um par de ressonadores é acoplado eletricamente o outro par realiza um acoplamento magnético. O método é aplicado utilizando duas tecnologias diferentes. A primeira, onde são utilizados ressonadores em anel cortado, desenvolvidos em microfita para realização de filtros na banda X de frequência. Neste caso, foram desenvolvidos um filtro de quarta e um de sexta ordem. A segunda tecnologia onde o método foi implementado é conhecida como SIW (Substrate Integrated Waveguide), operando na faixa de frequência da banda K. Neste caso, cavidades integradas ao substrato foram utilizadas como ressonadores e sendo acopladas entre si por meio de vias metalizadas inseridas no substrato. Para determinar as características dos acoplamentos, foi realizada análise do comportamento dos campos elétrico e magnético na estrutura. / [en] In this work, a study is presented for the development of bandpass filters whose transfer function is called quasi-elliptic or semi-elliptical. This name comes from its main feature which is to present only a pair of attenuation poles in the rejection band. The pair of poles is determined by cross-coupling between two pairs of resonators disposed non-adjacently, wherein while one pair of resonators is coupled electrically, the other pair performs a magnetic coupling. The method is applied using two different technologies. The first one uses a split ring resonator developed in microstrip for the realization of filters in the X Band frequency spectrum. In this case, a fourth and sixth order filter was developed. The second technology where the method was implemented is known as SIW (Substrate Integrated Waveguide), operating in the frequency range of K Band. In this case, cavities integrated into the substrate were used as resonators and were coupled to each other by means of metallic substrates inserted into the substrate. To determine the coupling characteristics, the behavior of the electric and magnetic fields in the structure was analyzed.

K-Band (18 to 26 GHz) dielectric resonator oscillators are typically used as a local oscillator in most K-Band digital transmitter/receiver topologies. Traditionally, the oscillator itself is made up of an active device, a dielectric resonator termination network, and a passive load matching network. The termination network embodies a cylindrical high permittivity dielectric resonator that is coupled on the same plane as a current carrying transmission line. This configuration provides an adequate resonance needed for oscillation but has some limitations. In order to provide a high Q resonance the entire oscillator is placed in a metal box to prevent radiation losses. This increases the overall size of the device and makes it difficult to integrate in smaller transceiver topologies. Secondly, a tuning screw is required to help excite the dominant mode of the resonator to achieve the high Q response. This can cause problems in precision due to the mechanical jitter of the screw inherent in mobile devices. By embedding this resonator inside the substrate it is possible to realize a very high Q resonance at a desired frequency and remove the need for a metal cavity and tuning screw. An additional advantage can be seen in terms of overall size reduction of the oscillator circuit. To demonstrate the feasibility of utilizing a dielectric resonator embedded within a substrate, a K-Band oscillator proof of concept has been designed, fabricated, and tested. The oscillator is comprised of a low noise active transistor device, an embedded k-band dielectric resonator and a passive transmission line load network. All elements within the oscillator are optimized to produce a steady oscillation near 20 GHz. Preliminary investigations of a microstrip resonator S-band (2-3 GHz) oscillator are first discussed. Secondly, various challenges in design and fabrication are discussed. Thereafter, simulated and measured results of the embedded DRO structure are presented. Emphasis is placed on output oscillation power and low phase noise. With further development, the entire oscillator can be embedded within the substrate leaving only the active device on the surface. This allows for a considerable reduction in material cost and simple integration with miniaturized digital transmitter/receiver devices.

[ES] Esta tesis aborda temas de especial interés en el diseño de antenas en la banda de milimétricas. Hui en dia, implementar components passius per a operar en la banda de mil·limètriques i assegurar el contacte i l'alineament metàl·lic apropiat entre peces, resulta un desafiament complex. Habitualment les línies de transmissió i les guies d'ones metàl·liques són les solucions adoptades, però en el primer cas es presenten pèrdues al ser solucions impreses i en el segon cas un mal contacte metàl·lic comporta fugues de camp. Per tant, s'estan explorant nous conceptes que solucionen estos problemes. La tecnología Gap Waveguide (GW) resulta adecuada ya que no requiere de contactos metálicos. En los últimos años han surgido las agrupaciones de antenas basadas en la tecnología Gap Waveguide y son un candidato prometedor para satisfacer algunas de las necesidades mencionadas. La tecnología GW ha demostrado ser atractiva para dispositivos de milimétricas porque permite redes de distribución completamente metálicas de una manera más simple que las guías de onda convencionales. Por tanto, estas redes tienen muy bajas pérdidas pero además son simples de fabricar. Esto es posible gracias a la capacidad de las GW de confinar de forma segura la propagación de ondas electromagnéticas por medio de una estructura que no requiere de contacto. Durante la última década, se han hecho avances importantes en la tecnología GW y en la literatura se pueden encontrar un buen número de antenas basadas en GW. Esta tesis va un paso más allá en la contribución de este tipo de antenas. Aquí, no solo se presentan antenas con polarización lineal, como suelen ser las desarrolladas hasta ahora, sino también con polarización dual, circular y duales en banda. Estas aportaciones son especialmente atractivas dentro del campo de las comunicaciones por satélite en movimiento (SATCOM on-the-move). Además, se han explorado nuevas redes de distribución que permiten antenas planas más compactas, más ligeras. / [CAT] Esta tesi aborda temes d'especial interés en el disseny d'antenes en la banda de mil.limètriques. Hui en dia, implementar components passius per a operar en longituds d'onda tan xicotetes (de l'orde de mil.límetres) i assegurar el contacte i l'alineament metàl-lic apropiat entre peces, resulta un desafiament complex. Habitualment les línies de transmissió i les guia d'ones metàl.liques són les solucions adoptades, però en el primer cas es presenten pèrdues al ser solucions impreses i en el segon cas un mal contacte metàl.lic comporta fugues de camp. Per tant, s'estan explorant nous conceptes que solucionen estos problemes. La tecnologia Gap Waveguide (GW) resulta adequada ja que no requerix de contactes metàl.lics. En els últims anys han sorgit les agrupacions d'antena basades en la tecnologia Gap Waveguide i són un candidat prometedor per a satisfer algunes de les necessitats mencionades. La tecnologia GW ha demostrat ser atractiva per a dispositius de banda d'ones mil-limètriques perquè permet xarxes de distribució completament metàl-liques d'una manera més simple que les guies d'onda convencionals. Per tant estes xarxes tenen baixes pèrdues peró, a més, són simples de fabricar. Açò és possible gràcies a la capacitat de les GW de confinar de forma segura la propagació d'ones electromagnètiques per mitjà d'una estructura que no requerix de contacte. Durant l'última dècada, s'han fet avanços importants en la tecnologia GW i en la literatura es poden trobar un bon nombre d'antenes basades en GW. Esta tesi va un pas més enllà en la contribució d'este tipus d'antenes. Ací, no sols es presenten antenes amb polarització lineal com solen ser les desenrotllades fins ara, sinó també antenes amb polarització dual, circular i inclús antenes duals en banda. Estes aportacions són especialment atractives dins del camp de les comunicacions per satèl.lit en moviment (SATCOM on-the-move). A més també s'han explorat noves xarxes de distribució que permeten obtindre antenes planes més compactes, més lleugeres. / [EN] This thesis deals with topics of special interest regarding the design of antennas at the mm-wave band. Today, implementing passive components that operate in the mm-wave band and to ensure the appropriate metallic contact is challenging. Commonly, conventional planar transmission lines and hollow metallic waveguides are the usual solutions but they present high losses or they do not ensure a good metallic contact. So, new concepts must be explored. Gap Waveguides (GWs), result suitably since they do not require metallic contact for shielding. Antenna arrays in Gap Waveguide Technology (GW) emerges as one promising candidate to naturally meet some of the mentioned needs. GW technology has demonstrated to be effective for mm-wave band devices because it enables full-metal distribution networks in a much simpler way than conventional waveguides. Very low distribution losses can be achieved preserving at the same time the assembly simplicity of multilayer microstrip feeding networks. This unique feature is a consequence of gap waveguides ability to safely confine the electromagnetic wave propagation through a contactless structure. During the last decade, there have been important advances in GW technology and a good number of gap waveguide-based arrays can be found in the literature. This thesis goes a step further in the contribution to mm-wave gap waveguide antennas. Here, antennas with linear polarization as well as circular or dual polarization are proposed. Dual band antennas has also been explored. These contributions have been carried out with a focus on satellite communications on-the-move. In addition, new distribution networks have also been explored to obtain more compact, low-profile and lighter antennas. / Ferrando Rocher, M. (2018). Gap Waveguide Array Antennas and Corporate-Feed Networks for mm-Wave band Applications [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/115933 / TESIS

Wireless operation, near-field or far-field, is a core functionality of any mobile or autonomous system. These systems are battery operated or most often utilize energy scavenging as a means of power generation. Limited access to power, expected long and uninterrupted operation, and constrained physical parameters (e.g. weight and size), which limit overall power harvesting capabilities, are factors that outline the importance for innovative low-power approaches and designs in advanced low-power wireless applications. Low-power approaches become especially important for the wireless transceiver, the block in charge of wireless/remote functionality of the system, as this block is usually the most power hungry component in an integrated system-on-chip (SoC). Three such advanced applications with stringent power requirements are examined including space-based exploratory remote sensing probes and their associated radiation effects, millimeter-wave phased-array radar for high-altitude tactical and geological imaging, and implantable biomedical devices (IMDs), leading to the proposal and implementation of low-power wireless solutions for these applications in SiGe BiCMOS and CMOS and platforms.