Dissertations / Theses on the topic 'Dielectic rod'
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1
Wells, Colin G. "Analysis of shielded rectangular dielectric rod waveguide using mode matching." University of Southern Queensland, Faculty of Engineering and Surveying, 2005. http://eprints.usq.edu.au/archive/00001524/.
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The limit of current technology for mobile base station filters is the multimode filter, in which each cavity supports two (or possibly three) independent degenerate resonances. Shielded dielectric resonators with a rectangular cross-section are useful in this application. In the design of these filters, manufacturers are using software packages employing finite element or finite difference time domain techniques. However, for sufficient accuracy these procedures require large numbers of points or elements and can be very time consuming. Over the last decade research using the mode matching technique has been used to solve this kind of difficulty for various types of filter design and waveguide problems. In this thesis a mode matching method and computer program is developed to calculate the propagation coefficients and field patterns of the modes in a shielded rectangular dielectric rod waveguide. Propagating, complex, evanescent and backward wave modes are included and the work shows the presence of a dominant mode, and other fundamental modes, not previously identified. The effect of the shield proximity on the propagation characteristics and mode spectrum is investigated, together with the limitations on the accuracy of the mode matching method. In addition, the fields within the shielded rectangular dielectric rod waveguide, are used to calculate the attenuation coefficient of the dominant and fundamental modes. The influence on the attenuation coefficient of the proximity of the shield to the rod is also evaluated for these modes and limitations on accuracy are discussed. The calculated numerical results for the propagation and attenuation coefficient values are verified by measurement. The propagation coefficients results are typically within 2% of those measured. Verification of the attenuation coefficient results is achieved by comparing calculated and measured Q at the resonant frequencies of a number of shielded rectangular dielectric rod resonators. The difference between calculated and measured Q values is on average less than 4%. In the absence of a full solution of the shielded rectangular dielectric rod resonator, these results provide useful design information for this structure. In addition, the work reported in this thesis provides a basis for a full electromagnetic solution of this type of resonator. This would encompass the cubic dielectric resonator in a cubical cavity.
2
Wainwright, Gregory David. "Development of an Ultra-Wideband Circularly Polarized Multiple Layer Dielectric Rod Antenna Design." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1437566560.
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Goodson, Craig Carl. "Simulation of Microwave Heating of Mullite Rods." Thesis, Virginia Tech, 1997. http://hdl.handle.net/10919/35768.
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Microwave processing has been studied as an alternate heating technique over conventional heating for industrial applications. Some advantages include quicker and more uniform heating. Also, microwave energy offers the advantage of localized heating and smaller-sized equipment. Many ceramics, however, are difficult to heat using microwave energy by reason of the strong temperature dependence of the dielectric loss. The ability of a ceramic to absorb microwave energy, a measure of its dielectric loss, increases with temperature which makes the material more susceptible to thermal runaway. The purpose of this research is to develop a model that accurately reproduces experimental data and can be used to explore new applicator designs for continuous processing of such ceramics. A two-dimensional numerical model, created for this purpose, assumes that the ceramic is a circular cylinder that moves either longitudinally through a microwave cavity of given dimensions. By adjusting the electromagnetic field so that the absorbed power matches the measured power, the model successfully imitates experimental results and avoids thermal runaway while achieving high temperatures.Master of Science
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Cox, Gavin J. "Techniques for pattern control of a dielectric rod antenna suitable for use in mobile communications." Thesis, Loughborough University, 2002. https://dspace.lboro.ac.uk/2134/12693.
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This thesis describes the development of antennas suitable for mobile coinmunication systems based on a dielectric rod antenna fed from circular waveguide. Pattern control of the antenna is implemented using a combination of Frequency Selective Surface (FSS) elements and metallic endcaps placed on the antenna Both linear and circular polarised feeds have been made for these antennas to ensure they are suitable for a wide range of applications. The suitability of the dominant and next, higher order, waveguide mode were investigated and conclusions drawn as to their suitability for this type of antenna. The antennas were extensively modelled using a commercial TLM based solver and the results of these simulations were compared to the comprehensive set of antenna pattern measurements and S-parameter measurements obtained for the prototype antennas.
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Liu, Chia-Wei. "Development of Automatic Design Optimization Method for Ultrawide Bandwidth (UWB) Multi-Layer Dielectric Rod Antenna." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1306512723.
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Li, Liang-shi. "Anisotropy in CdSe quantum rods." Berkeley, Calif. : Oak Ridge, Tenn. : Lawrence Berkeley National Laboratory ; distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, 2003. http://www.osti.gov/servlets/purl/827094-DOIqqD/native/.
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Thesis (Ph.D.); Submitted to the University of California at Berkeley, Berkeley, CA (US); 1 Sep 2003.Published through the Information Bridge: DOE Scientific and Technical Information. "LBNL--55023" Li, Liang-shi. USDOE Director. Office of Science. Office of Basic Energy Sciences (US) 09/01/2003. Report is also available in paper and microfiche from NTIS.
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Saarenketo, T. (Timo). "Electrical properties of road materials and subgrade soils and the use of Ground Penetrating Radar in traffic infrastructure surveys." Doctoral thesis, University of Oulu, 2006. http://urn.fi/urn:isbn:9514282221.
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Abstract
This PhD thesis is composed of a synopsis and five published papers that are focused on both the research results of studies on electrical properties of road materials and subgrade soils and their seasonal changes and the use of Ground Penetrating Radar technique in traffic infrastructure surveys. The data for this survey was collected mainly in Finland, Texas, Scotland and Sweden and thus presents many kinds of road materials, subgrade soils and climate conditions.
The synopsis of this work begins with a presentation of the theory and basic principles of GPR techniques. Special attention is given to the dielectric properties and seasonal changes of unbound road materials and subgrade soils. The synopsis also presents different kinds of GPR hardware systems as well as recommendations and experiences from different data collection, processing and interpretation techniques. Special attention is given to a method whereby GPR data is integrated with other road survey data and then analysed using a number of structural diagnostic methods. Finally, the synopsis provides an overview of of the various GPR applications on roads and streets, bridges, railways and airports.
The laboratory test results presented in this work show that the relationship between dielectric value and increasing water content is not linear or exponential but more likely a series of logarithmic functions. Laboratory results also showed that dielectric dispersion, which can be related to poorly performing subgrade soils and road aggregates, takes place mainly in loosely bound adsorption water and capillary water layer. As such these moisture sensitive problem materials can also be identified during the dry summer seasons when they are stiff. Dielectric value and electrical conductivity can also be related to other technical properties of road materials and subgrade soils such as frost susceptibility, shear strength, plastic limit, compaction degree and voids content. Laboratory tests and field data collected using the Percostation technique also demonstrate that a knowledge of seasonal changes and thermodynamics is very important in understanding and modelling the mechanical behaviour of road structures. Finally, laboratory and field tests indicate that colloids have an important role in the failure mechanism of the road materials.
This research demonstrates that the GPR technique not only gives valuable structural information on the different types of structures and subgrade soils but it provides a wide range of information of the electrical properties of the materials under survey which can be further related to their mechanical performance. The best information will be gained if GPR data is analysed together with other non destructive testing data collected form the roads, railways and airports.
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Qassim, K. A. S. "Optimisation of focal plane arrays for microwave imaging : printed Yagi, dielectric rod and constant width slot antennas are investigated and optimised for close stacking in focal plane arrays intended for microwave imaging." Thesis, University of Bradford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320761.
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Chen, Feng. "Sustainable Implementation of Electrified Roads : Structural and Material Analyses." Doctoral thesis, KTH, Bro- och stålbyggnad, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-195669.
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Given the promise of the Inductive Power Transfer (IPT) technology for eRoad applications, the potential challenges for a successful integration of dynamic IPT technology into the physical road structure are explored extensively in this research work. The Finite Element Method (FEM) is selected for studying the structural performance of an eRoad under operational conditions. In this, an energy-based finite strain constitutive model for asphalt materials is developed and calibrated, to enable the detailed investigation of the structural response and optimization of the considered eRoad. In the context of enabling both dynamic charging and autonomous driving for future electric vehicles, the influences to the pavement (rutting) performance by the changed vehicle behaviour are investigated as well. Moreover, to study the effect on the IPT system by the integration, the potential power loss caused within eRoad pavement materials is further examined by a combined analytic and experimental analysis. The direct research goal of this Thesis is therefore to enhance the possibility of a sustainable implementation of the eRoad solutions into the real society. At the same time, it aims to demonstrate that the road structure itself is an important part of smart infrastructure systems that can either become a bottleneck or a vessel of opportunities, supporting the successful integration of these complex systems.Givet de förutsättningar som induktiv energiöverföring (IPT Inductive Power Transfer) har för eRoad applikationerna, utforskas möjligheterna för en framgångsrik integration av dynamisk IPT i den fysiska vägkonstruktionen på en djupgående nivå i detta forskningsarbete. Speciellt har finita elementmetoden använts för att studera det strukturella beteendet hos en e-väg under driftsmässiga förhållanden. Inom detta har en energibaserad konstitutiv model för stora töjningar utvecklats och kalibrerats för att möjliggöra detaljerade undersökningar av strukturell respons och optimering av de föreslagna e-vägarna. I samband med att möjliggöra både dynamisk laddning och autonom körning för framtida elektriska fordon, har beläggningars (spårbildnings)egenskaper studerats utifrån de laddande fordonen beteende. Dessutom för att studera effekten av IPT-systemet har den potentiella energiförlusten inom e-vägars beläggningsmaterial undersökts genom en kombinerad analytisk och experimentell undersökning. Som sådant är det direkta forskningsmålet med denna avhandling att utöka möjligheterna för en hållbar implementering av eRoad systemet inom det verkliga samhället. Samtidigt är målet att visa att vägkonstruktionen i sig själv är en viktig del av det smarta infrastruktursystemet som antingen kan bli en flaskhals eller en bärare av möjligheter, stödjande en framgångsrik implementering av dessa komplexa system.
QC 20161108
10
Candelier, Philippe. "Contribution à l'amélioration de la fiabilité des mémoires non volatiles de type flash EEPROM." Université Joseph Fourier (Grenoble ; 1971-2015), 1997. http://www.theses.fr/1997GRE10245.
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L'augmentation continue de la densite d'integration des memoires non-volatiles de type flash eeprom passe par la comprehension des mecanismes de degradation intervenant dans le cadre du fonctionnement de ces memoires. Nous avons pu correler les degradations observees sur des dispositifs elementaires (transistors et capacites) aux derives des caracteristiques de la cellule flash. Cette etude demontre que de nouveaux modes de fonctionnement devront etre envisages. Le mode d'effacement par la source, habituellement utilise, pose des problemes d'optimisation technologique pour les cellules de faible longueur de grille (generation de trous chauds difficile a controler). Il devra vraisemblablement etre remplace par l'effacement fn qui est plus fiable pour les criteres d'endurance et de retention apres endurance. Parmi les degradations observees, le probleme principal est l'augmentation de la perte de charge avec l'amincissement des dielectriques et avec la degradation de l'oxyde de grille lors des cycles ecriture/effacement. Face au premier probleme, la mise en place d'une fonction de rafraichissement periodique semble necessaire. Face au second probleme, l'effacement fn a ete optimise en minimisant le champ electrique dans l'oxyde de grille par l'utilisation d'impulsions trapezoidales. Des progres technologiques importants (dielectriques interpolysilicium deposes, isolation laterale de type box) ont ensuite ete introduits dans le procede de fabrication afin permettre une integration plus poussee. La validation de ces evolutions technologiques ouvre les portes de la generation de cellules flash 0. 25 m. Finalement, face au probleme d'augmentation de la densite d'integration, la programmation multi-niveaux est une solution simple dont la fiabilite a ete amelioree grace a la realisation d'un systeme de programmation convergente. La faisabilite d'un doublement de capacite memoire a alors ete demontree.
11
Zhang, Kai-Cheng, and 張凱程. "Dielectric constants measurement of zinc nanoparticles implemented with a dielectric rod cavity." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/79113062764516518031.
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Sotoodeh, Zahra. "Design of a mm-wave Planar CPW-fed Tapered Dielectric Rod Antenna." Thesis, 2011. http://hdl.handle.net/10012/6402.
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The demand for high data rate transfers in short range areas have been increasing significantly. Millimeter wave communication systems can fulfill the requirements for such applications due to the availability of wide bandwidths at these frequencies. Particularly, 60 GHz frequency band is more appropriate among other mm-wave bands because of the oxygen energy absorption resonance at this frequency.
Millimeter wave antennas are one of the desired components in short range wireless communications. High gain and broadband antennas are required for this purpose.
In this study, a fully planar 60 GHz antenna is introduced. Tapered dielectric rod antenna is chosen to achieve high radiation efficiency. The antenna is designed on two common substrates with high permittivity: alumina (Al2O3) and high resistive Silicon. Both substrates are very low loss and many designs for front-end components are developed on these substrates due to their high permittivity. In other words, the proposed antenna can be integrated with the front-end platform in the same substrate. In addition, the antenna feeding is the CPW line which makes it a convenient solution for integration of the antenna with RF front-ends such as MMICs or MEMS circuits in this range of frequency.
13
Chen, Huanyu. "Fast Methods for Millimeter-wave Dielectric Resonator and Antenna Analysis and Design." Thesis, 2009. http://hdl.handle.net/10012/4306.
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Ever-increasing interest in millimeter-wave and terahertz spectrum has prompted research and development of novel passive components working at these frequencies. Compared with the conventional planar components, non-planar dielectric devices become more attractive as frequencies increase due to their higher quality factors and dimensional tolerances. In this thesis, we present fast methods to analyze the millimeter-wave dielectric resonator and rod antenna.
First, an analytical method has been developed to evaluate resonant frequencies, quality factors of the Whispering Gallery Mode (WGM) disk resonators and also the resonator-waveguide coupling. A numerical solver based on full-wave finite element method is implemented to verify the analytical result. This analytical model provides a solution for fast design and optimization of WGM resonators in filter and sensor applications.
Secondly, a fast analytical approach based on local mode theory is introduced to calculate the radiation from tapered dielectric rod antenna. This efficient approximate model consumes much less computing resources and time, and demonstrates good agreements with full-wave numerical results. It supplies a quantitative way to understand the radiation mechanism and interaction between different parts of the antenna. Based on this, design criteria for the taper profile of rod antennas are given.
14
Yang, Yueh-Chieh, and 楊岳杰. "Surface-Wave Modal Analysis of Strip-Grated Dielectric Coated Metal Rod by Asymptotic Strip Boundary Conditions." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/93gmg4.
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碩士國立交通大學
電信工程研究所
107
In this thesis, the surface-wave propagating on the strip-grated dielectric coated metal rod is analyzed by using the asymptotic strip boundary conditions (ASBC). Starting from the vector potentials of the classical electromagnetism for the TE and TM modes to the system matrix equations, the characteristic equation and the electric and magnetic field expressions in closed form are derived. The dispersion diagram and the field distribution of the first three modes are obtained and compared with the results generated by the commercial full wave solver: CST Microwave Studio to validate the method. The comparison of the time cost to generate the dispersion diagrams by the ASBC method and the CST Microwave Studio have been shown. The results show that the method using ASBC has high efficiency and qualified accuracy. The basic parametric studies pertain to the dispersion diagrams change in response to the geometrical parameters are done. By comparing the dispersion diagrams of this strip-grated structure and the dielectric-covered metal rod, the property that the stronger confinement of the surface-wave on this strip-grated cylindrical structure is concluded. The surface-wave modal analysis with dielectric loss included is also investigated by this asymptotic method. The measured results of the dispersion and the energy level against the radial distance on the strip-grated rod have also been presented.
15
Wu, Jian-Yang, and 吳健暘. "Study on the conduction band of photonic cryatal and dielectric rods waveguide." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/04990246493813109715.
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碩士國立中央大學
光電科學研究所
93
We propose a new type of optical waveguide that consists of several dielectric rods. In this new type of optical waveguide, energy will localize in every rod in some frequency, as light propagating in strongly localized cavities. High transmission is observed for various waveguide structures. All angle bends in dielectric rods waveguide can be happened, but photonic crystal waveguide can’t. And it uses less radius of curvature then classical dielectric waveguide. The waveguide may have practical importance for development of optoeletronic components and circuits.
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Li, Yang 1982. "Investigation of wave propagation and antenna radiation in forested environments." Thesis, 2011. http://hdl.handle.net/2152/ETD-UT-2011-05-3092.
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Recently, there is emerging interests in deploying wireless sensor networks in forests for applications such as forest fire detection, environmental monitoring and remote surveillance. One challenge in the design of such networks is to ensure reliable communication between sensors located near the ground and over short distances. However, the propagation mechanisms in this type of scenario are complex and not well understood. Furthermore, the design of antennas that can exploit the resulting propagation mechanisms for optimal power transfer remains an open question.
The objective of this dissertation is to understand wave propagation and antenna radiation in forested environments in the HF/VHF frequency range. To achieve this objective, several forest scaled models are introduced. The first scaled forest model is a periodic metal cut-wire array. The transmission data inside the cut-wire array are simulated and measured. The propagation mechanisms inside the array are extracted. Several interesting propagation phenomena associated with surface waves and leaky waves are observed and explained.
Next, a dielectric rod array consisting of water-filled straws is investigated as a more realistic forest model. Water is chosen since its dielectric constant in the microwave range is close to that of tree trunks in the HF/VHF frequencies. The propagation mechanisms in the water rod array are investigated through scaled model measurements in the laboratory, numerical simulations and an effective medium theory. Randomization effects due to rod spacing and rod height on the propagation mechanisms are also studied.
Finally, the transmission data in a real forest are collected in the HF/VHF frequency range to corroborate the findings from the models. The measurement site is located at Bastrop, Texas. For comparison, the transmission data are also measured in an open field. The transmission data are processed and the resulting propagation mechanisms are extracted and compared with the model predictions.
As an extension of the propagation study, the potential to achieve directive antenna radiations in a forest is explored. A simple metal cut-wire array environment is considered for ease in modeling. For the case when both the transmit antenna and the receive antenna are embedded inside the array, two design ideas are presented. The first design tries to couple the antenna radiation into the dominant propagation mechanism through phase matching and the second design uses a closely spaced Yagi array to decouple the antenna from its surrounding medium. For the case when the transmit antenna is embedded inside the array and the receive antenna is located outside the array, the leaky wave mechanism is explored to achieve directive radiation. These designs are verified through theoretical predictions, numerical simulations and prototype measurements.text
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Wei-ChenYen and 顏瑋辰. "A Novel Pd/Pt/High-K dielectric/n-Silicon MIS Schottky Diode with 3D Nano Rod Structure for Hydrogen Sensing Applications." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/11098908232294988527.
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碩士國立成功大學
微電子工程研究所碩博士班
100
We developed the 3D nano rod structure Al/PdPt/ high-K/n-Si/Al MIS Schottky diode for H2 gas sensing applications. Firstly, the Si nano rods were formed on the n type (100) Si substrates with AgNO3and HF mixed etching solution. Then deposited the intrinsic high-K thin films (diamond、HfO2、TiO2) with HWCVD(Hot-Wire CVD) and sputtering system. Followed by deposition of various metal such as Pd、Pt and Pd/Pt as catalytic layer. In final, the device was completed by evaporation of Al on the top and bottom, respectively as electrode contact. We optimized the 3D hydrogen sensor with the following studies: (a) using different catalytic material Pd、Pt and Pd/Pt, (b) to deposit diamond、HfO2 and TiO2 as intrinsic dielectric layer, (c) comparison of the 3D nano rod structure with the conventional 2D thin film type, and (d) to vary intrinsic dielectric layer thickness. Besides, to get the best quality of diamond as the intrinsic layer, we used Raman, XRD, SEM and AFM, respectively for bond structure measurement, crystallinity analyzing, surface roughness, and morphology inspection. Experimental results show that composite of Pd/Pt has the highest activity to catalytic hydrogen atoms into ions, and suppress the hydrogen blister issue. Besides, the nano rods structure indeed can promote sensitivity from 1350% of the conventional 2D thin film type to 2860%. Furthermore, use of diamond as i-layer achieves the fast response time of 9sec, and the highest sensitivity of 217% respectively for 100ppm H2 ambient with the condition of - 3V, 200oC. In addition, we found the developed 3D MIS diode H2 sensor has no significant sensing action to CO2 and alcohol gases Under 150 oC /100ppm H2 ambient, the developed 3D H2 sensor has the best performances of 202% and 9 sec, respectively for sensitivity of and response time , which are better than the reported Pt/HfON/SiC MIS Schottky diode of 53% and 10.5 sec under same conditions.
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Wei, Han-Lee, and 李威漢. "Analysis of Strip-Grated Dielectric-Coated Metal Rods for the Study of Conductor Attenuation and Field Localization." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/y4t758.
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碩士國立交通大學
電信工程研究所
107
In this thesis, we use an analytical method with high accuracy to analyze the strip-grated dielectric-coated metal rod. The surface-wave dispersion diagrams and field distributions may be generated from this method and validated with those simulated by commercial full wave solver. Because of the surface-wave traveling on this structure at high power, high frequencies and over long distances, conductor losses are investigated in this thesis. Besides, parametric studies for field localization on the surface of rod are also reported. In order to improve the coupling between the fast space waves emitted by the horn to the slow surface-waves supported by the rod, we design a coaxial-type coupling device by using CST simulations. Finally, prototypes of the strip-grated rod and coaxial couplers were also manufactured and measured; the measurement of dispersion and field decay along the radial direction are also presented.