Dissertations / Theses: 'Microwave'

1

Hopkins, Glenn Daniel. "Empirical characterization of a plated-through-hole interconnect for a multilayer stripline assembly at microwave frequencies." Thesis, Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/15658.

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Daian, Mihai Stelian. "Thedevelopment and evaluation of new microwave equipment and its suitability for wood modification." Swinburne Research Bank, 2006. http://hdl.handle.net/1959.3/38305.

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Thesis (PhD) - Swinburne University of Technology, Industrial Research Institute Swinburne, Faculty of Engineering and Industrial Sciences, 2006.
[A thesis submitted for the degree of Doctor of Philosophy], Industrial Research Institute Swinburne, Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, 2006. Typescript. Includes bibliographical references (p. 157-165)

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Zimmer, Aline Katharina. "Investigation of the impact of turbine blade geometry on near-field microwave blade tip time of arrival measurements." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26558.

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Thesis (M. S.)--Aerospace Engineering, Georgia Institute of Technology, 2009.
Committee Chair: Jagoda, Jechiel; Committee Co-Chair: Jacobs, Laurence; Committee Member: Seitzman, Jerry. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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Matasane, Matasane Clement. "Investigation into the monitoring of microwaves in microwave cavities using optical techniques." Thesis, Peninsula Technikon, 2002. http://hdl.handle.net/20.500.11838/1076.

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Thesis (MTech (Electrical Engineering))--Peninsula Technikon, Cape Town, 2002.
Tne purpose of this research or study was to perform an investigation in the use of optical fibers as sensor elements in order to develop a millimetre wave instrument capable of measuring microwave power within microwave cavities. Included in the scope of the project was an investigation of microwaves and microwave power measurements techniques. The emphasis of the research work was to develop expertise in photonics, by modeling and developing a measuring technique using optical techniques. This was deemed to be highly beneficial in laboratory experimentation and for possible use by microwave technicians. The implementation was amongst others, done by means of computer simulation and associated hardware, together with fiber-optic accessories. In order to conduct this research a literature and technology survey of current non-optical microwave power measurement technique was done. With this a review different power measurements systems and their relationship towards microwave power measurements was conducted. Within the scope of the project, a study of fiber optics sensors and its components was also conducted, which enabled models for a Mach-Zehnder microwave sensor to be developed. This resulted in the development of inexpensive electronic signal conditioning and detection techniques to enable measurements that employed a Mach-Zehnder Interferometer for this sensor technique. Finally, as microwaves are difficult to measure with pure electronic equipment, different approaches were made to investigate the temperature changes and other parameters on optical fiber to avoid damage to it. The specifications of hardware and circuitry suitable to measure these effects were determined.

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Doolittle, John William Jr. "Synthesis of microporous faujasitic zincophosphates in novel environments." The Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=osu1116983708.

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Nugroho, Agung Tjahjo. "Microwave tomography." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/microwave-tomography(1000bea8-f286-42dc-9def-8aa09411160e).html.

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This thesis reports on the research carried out in the area of Microwave Tomography (MWT) where the study aims to develop inversion algorithms to obtain cheap and stable solutions of MWT inverse scattering problems which are mathematically formulated as nonlinear ill posed problems. The study develops two algorithms namely Inexact Newton Backtracking Method (INBM) and Newton Iterative-Conjugate Gradient on Normal Equation (NI-CGNE) which are based on Newton method. These algorithms apply implicit solutions of the Newton equations with unspecific manner functioning as the regularized step size of the Newton iterative. The two developed methods were tested by the use of numerical examples and experimental data gained by the MWT system of the University of Manchester. The numerical experiments were done on samples with dielectric contrast objects containing different kinds of materials and lossy materials. Meanwhile, the quality of the methods is evaluated by comparingthem with the Levenberg Marquardt method (LM). Under the natural assumption that the INBM is a regularized method and the CGNE is a semi regularized method, the results of experiments show that INBM and NI-CGNE improve the speed, the spatial resolutions and the quality of direct regularization method by means of the LM method. The experiments also show that the developed algorithms are more flexible to theeffect of noise and lossy materials compared with the LM algorithm.

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Misner, Scottie, Carol Curtis, and Evelyn Whitmer. "Microwave Cooking." College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2008. http://hdl.handle.net/10150/146454.

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2 pp.
Revision of 1998 title by Abgrall and Misner
Microwave ovens are safe to use for defrosting, reheating, and cooking food. However "cold spots" can occur in microwaved foods because of the irregular way the microwaves enter the oven and are absorbed by the food. This article provides information on how to cook food evenly and safely in microwave ovens.

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Contreras, Lizarraga Adrián Arturo. "Multimodal microwave filters." Doctoral thesis, Universitat Politècnica de Catalunya, 2013. http://hdl.handle.net/10803/134931.

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This thesis presents the conception, design and implementation of new topologies of multimodal microwave resonators and filters, using a combination of uniplanar technologies such as coplanar waveguide (CPW), coplanar strips (CPS) and slotlines. The term "multimodal" refers to uniplanar circuits in which the two fundamental modes of the CPW propagate (the even and the odd mode). By using both modes of the CPW, it is possible to achieve added functions, such as additional transmission zeros to increase the rejection, or to attenuate harmonic frequencies to improve the out-of-band rejection. Moreover, it is demonstrated that by using multimodal circuits, it is possible to reduce the length of of a conventional filter up to 80%. In addition to bandpass filters, new topologies of compact band-stop filters are developed. The proposed band-stop filters make use of slow-wave resonators to decrease the total area of the filters and achieve compact topologies. This work also addresses the development of synthesis techniques for each multimodal filter. The design equations were obtained from generalized multimodal circuits available in the literature, which have been adapted for each particular case and modeled as basic filter components, such as immitance inverters or lumped elements. By using the proposed synthesis equations, it is possible to design filters with a desired response and relative bandwidth. The use of the proposed synthesis enables a fast analysis and design of multimodal filters using circuit simulators. As an added feature, several reconfigurable and tunable filter topologies were demonstrated, using active devices (PIN diodes and varactors) or RF-MEMS. These new topologies demonstrate the flexibility of multimodal circuits. For the RF-MEMS-based tunable filters, different capacitive and ohmic switches were designed, fabricated and measured. As an example of the additional degrees of freedom using of RF-MEMS and multimodal CPW circuits, a reconfigurable filter using RF-MEMS switchable air-bridges as a reconfiguration device has been demonstrated in this work for the first time.

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Mavromatidis, Pavlos. "Microwave thermal spraying." Thesis, University of Liverpool, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.422101.

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Guler, Michael George. "Spherical microwave holography." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/15055.

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Naylon, Alexander. "Microwave resonant sensors." Thesis, Cardiff University, 2011. http://orca.cf.ac.uk/15525/.

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Microwave resonant sensors use the spectral characterisation of a resonator to make high sensitivity measurements of material electromagnetic properties at GHz frequencies. They have been applied to a wide range of industrial and scientific measurements, and used to study a diversity of physical phenomena. Recently, a number of challenging dynamic applications have been developed that require very high speed and high performance, such as kinetic inductance detectors and scanning microwave microscopes. Others, such as sensors for miniaturised fluidic systems and non-invasive blood glucose sensors, also require low system cost and small footprint. This thesis investigates new and improved techniques for implementing microwave resonant sensor systems, aiming to enhance their suitability for such demanding tasks. This was achieved through several original contributions: new insights into coupling, dynamics, and statistical properties of sensors; a hardware implementation of a realtime multitone readout system; and the development of efficient signal processing algorithms for the extraction of sensor measurements from resonator response data. The performance of this improved sensor system was verified through a number of novel measurements, achieving a higher sampling rate than the best available technology yet with equivalent accuracy and precision. At the same time, these experiments revealed unforeseen applications in liquid metrology and precision microwave heating of miniature flow systems.

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Smith, Ian Christopher. "Wideband microwave mixers." Thesis, University of Leeds, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328957.

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Anbaran, Seyed Reza Ghaffariyan. "Microwave assisted pultrusion." Thesis, University of Manchester, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.481526.

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Llamas, Garro Ignacio. "Micromachined microwave filters." Thesis, University of Birmingham, 2003. http://etheses.bham.ac.uk//id/eprint/102/.

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Microwave circuits in the millimetre wave region demand low loss, and low dispersion transmission lines. The work carried out in this thesis is on low loss transmission lines and filters, based on a square coaxial transmission line which is made only of metal, avoiding dielectric and radiation losses. The metal structure inside the square coaxial transmission line is supported by stubs, which provide the mechanical support for the centre conductor for the coaxial transmission lines and filters. The coaxial structure is made by stacking thick planar layers of material to suit microfabrication, providing the means to design high Q Microwave and RF passive devices, this transmission line structure is compact compared with a microstrip or a stripline, and gives better loss performance. Through this thesis, the way of optimising the square coaxial transmission line to provide a low loss will be presented, which will end in the presentation of one dielectric supported coaxial structure and three self supported filters, three of them were designed for the X-band, and one of them was designed for the Ka band. The application of the coaxial transmission line is demonstrated with wideband and narrow band designs.

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Cheng, Leong Ching. "Ferroelectric microwave circuits." Thesis, University of Birmingham, 2009. http://etheses.bham.ac.uk//id/eprint/6578/.

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Ferroelectric materials have been found to be particularly attractive materials for the development of tunable microwave devices over the past few decades due to their distinctive characteristic that is the variation of dielectric constant as a function of electric field. In this research project, the work on how the finite difference method (FDM), a computational technique, is modified to suit the evaluation of the cross-sectional field distribution of a ferroelectric-based transmission line is presented and the results are verified. The modified FDM was employed for determining the effective dielectric constant (Ɛeff) and the characteristic impedance (Zc) of ferroelectric-based structures where the spatial variation of dielectric constant was taken into consideration. A significant portion of this research is focused on the application of ferroelectric materials in designing tunable microwave devices. Two optimised phase shifters incorporating Barium Strontium Titanate (Ba0.5Sr0.5TiO3 or BST) ferroelectric thin-films are designed, fabricated and measured. One is based on simple coplanar waveguide (CPW) transmission line, and another is based on tapered CPW structure. To date, no work on tunable attenuator using ferroelectric materials has ever been reported, as contrary to other extensively studied ferroelectric-based tunable microwave devices, namely tunable resonators, filters, and phase shifters. In this work, a novel design of tunable attenuator integrating BST thin-films is presented and verified with experimental results from a similar design of tunable attenuator based on Roger/Duroid 6010LM substrate of dielectric constant 10.2. The application of ferroelectric thin-films enables continuous variation of attenuation under controlled bias voltages with significant size and weight reduction in the overall device.

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Geldenhuys, N. D. "Microwave frequency discriminators." Thesis, Stellenbosch : Stellenbosch University, 2001. http://hdl.handle.net/10019.1/52337.

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Thesis (MScEng)--University of Stellenbosch, 2001.
ENGLISH ABSTRACT: The topic of microwave frequency discriminators is introduced. Various applications and implementation techniques of these devices are given and discussed. This thesis may serve as reference foundation for future research on this topic. Discriminators are developed at both S- and X-band, with high linearity and good sensitivity. The systems used to implement these devices are developed as well. The S-band discriminator is used in a direct FM demodulation system, which works well.
AFRIKAANSE OPSOMMING: Hierdie is 'n inleiding tot die onderwerp van mikrogolf frekwensie diskrimineerders. Verskeie toepassings en implementeringstegnieke van hierdie toestelle word genoem en bespreek. Hierdie tesis kan dien as verwysings-raamwerk vir toekomstige navorsing oor hierdie onderwerp. Diskrimineerders is ontwikkel by beide S- en X-band, met 'n goeie lineariteit en sensitiwiteit. Die stelsels wat gebruik word om hulle te implementeer, is ook ontwikkel. Die S-band diskrimineerder is gebruik in 'n direkte FM demodulasie sisteem en werk goed.

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Rabjohn, Gordon G. (Gordon Glen) Carleton University Dissertation Engineering Electrical. "Monolithic microwave transformers." Ottawa, 1991.

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Devaraj, Kiruthika. "The centimeter- and millimeter-wavelength ammonia absorption spectra under jovian conditions." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42806.

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Accurate knowledge of the centimeter- and millimeter-wavelength absorptivity of ammonia is necessary for the interpretation of the emission spectra of the jovian planets. The objective of this research has been to advance the understanding of the centimeter- and millimeter-wavelength opacity spectra of ammonia under jovian conditions using a combination of laboratory measurements and theoretical formulations. As part of this research, over 1000 laboratory measurements of the 2-4 mm-wavelength properties of ammonia under simulated upper and middle tropospheric conditions of the jovian planets, and approximately 1200 laboratory measurements of the 5-20 cm-wavelength properties of ammonia under simulated deep tropospheric conditions of the jovian planets have been performed. Using these and pre-existing measurements, a consistent mathematical formalism has been developed to reconcile the centimeter- and millimeter-wavelength opacity spectra of ammonia. This formalism can be used to estimate the opacity of ammonia in a hydrogen/helium atmosphere in the centimeter-wavelength range at pressures up to 100 bar and temperatures in the 200 to 500 K range and in the millimeter-wavelength range at pressures up to 3 bar and temperatures in the 200 to 300 K range. In addition, a preliminary investigation of the influence of water vapor on the centimeter-wavelength ammonia absorptivity spectra has been conducted. This work addresses the areas of high-sensitivity centimeter- and millimeter-wavelength laboratory measurements, and planetary science, and contributes to the body of knowledge that provides clues into the origin of our solar system. The laboratory measurements and the model developed as part of this doctoral research work can be used for interpreting the emission spectra of jovian atmospheres obtained from ground-based and spacecraft-based observations. The results of the high-pressure ammonia opacity measurements will also be used to support the interpretation of the microwave radiometer (MWR) measurements on board the NASA Juno spacecraft at Jupiter.

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Imholt, Timothy James. "Carbon Nanotube/Microwave Interactions and Applications to Hydrogen Fuel Cells." Thesis, University of North Texas, 2004. https://digital.library.unt.edu/ark:/67531/metadc5796/.

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One of the leading problems that will be carried into the 21st century is that of alternative fuels to get our planet away from the consumption of fossil fuels. There has been a growing interest in the use of nanotechnology to somehow aid in this progression. There are several unanswered questions in how to do this. It is known that carbon nanotubes will store hydrogen but it is unclear how to increase that storage capacity and how to remove this hydrogen fuel once stored. This document offers some answers to these questions. It is possible to implant more hydrogen in a nanotube sample using a technique of ion implantation at energy levels ~50keV and below. This, accompanied with the rapid removal of that stored hydrogen through the application of a microwave field, proves to be one promising avenue to solve these two unanswered questions.

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Chalodhorn, Wonchalerm. "Use of microwave lenses in phase retrieval microwave holography of reflector antennas." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/14909.

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Goksu, Emel Iraz. "Fluidized Bed, Microwave And Microwave Assisted Fluidized Bed Drying Of Macaroni Beads." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/1098789/index.pdf.

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This study is aimed to compare the fluidized bed and microwave drying with microwave assisted fluidized bed drying. For this purpose, macaroni beads (2.4±
0.08 mm diameter) were dried from about 20% to 12% moisture content in a fluidized bed of 7.6 cm diameter, in a domestic microwave oven with a power of 609 W and in the fluidized bed placed in the microwave oven conditions. In the experiments with the fluidized bed three air temperatures
50, 60 and 70°
C at an air velocity of 2.3 m/s and in those with the microwave oven two power levels
50% and 100% were used. The drying curves indicated that the drying rate increased with the air temperature and microwave power in each drying method. Microwave assisted fluidized bed drying reduced the drying time by about 50% and 11% on the average compared with the fluidized bed and microwave drying, respectively. Therefore, it was concluded that the drying time was reduced more by the effect of microwave energy than the fluidization. The effective diffusivities in the fluidized bed and microwave assisted fluidized bed drying were found to be in the order of 4.125x10-11 and 8.772x10-11 m2/s on the average, respectively. The effective diffusivities for the fluidized bed drying were fitted to an Arrhenius type of equation and the magnitude of the activation energy was found to be in the order of 12595 kJ/kg mol.

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Secmeler, Ozge. "Comparison Of Microwave Drying And Microwave Mixed-bed Drying Of Red Peppers." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/1098979/index.pdf.

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The main objective of this work is to investigate whether the time required to dry red peppers in the diffusion controlled period can be reduced. For this purpose, the possibility of microwave drying in this period was studied. As comparison parameters the drying rates and color of the products were selected. The conventional drying was conducted under constant external drying conditions with air at 60 0C and 3.5 % RH and 1.0 m/s velocity in a batch dryer. For the microwave drying a domestic microwave oven with three power levels, 286, 397 and 560 W was used. Pre-experiments were done to obtain an insight on the possibility of moisture distribution within the structure of the red peppers and electrical field distribution inside the oven cavity. The non-uniformity due to the latter effect was tried to be overcome by designing and installing a six blade impeller into the bed having the symmetrical pair of blades fixed at three levels. Samples for the microwave drying experiments were prepared by drying the peppers from approximately 90% of moisture to 20% in 7 hours in the conventional dryer at 600C and then cutting them into pieces about 1x1 cm. Thus prepared samples were dried further in the microwave oven to 14% moisture content without and with the agitator. To compare the results, the effective diffusivity coefficients were calculated for all of the methods and parameters to enable the aimed comparison. These indicated that by using microwave drying, the drying time can be reduced by about 120 times. Further, by mixing the uniformity of drying and the drying rate could be improved. Considering color of the product, there was no significant difference with respect to the fresh samples after all operations.

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Fear, Elise Carolyn. "Microwave detection of breast cancer : a cylindrical configuration for confocal microwave imaging." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ58566.pdf.

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Vitolo, Maria Giovanna. "Microwave breast imaging reconstruction." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/10114/.

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In this thesis I analyzed the microwave tomography method to recognize breast can- cer. I study how identify the dielectric permittivity, the Helmoltz equation parameter used to model the real physic problem. Through a non linear least squares method I solve a problem of parameters identification; I show the theoric approach and the devel- opment to reach the results. I use the Levenberg-Marquardt algorithm, applied on COMSOL software to multiphysic models; so I do numerical proofs on semplified test problems compared to the specific real problem to solve.

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Dagne, Carl, Johan Bengtsson, and Ingemar Lindgren. "Microwave Wireless Communication System." Thesis, Halmstad University, School of Information Science, Computer and Electrical Engineering (IDE), 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-232.

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The purpose of the project was to develop the hardware to a microwave wireless system working

at the frequency 2.45 GHz. The functionality of the system should also be easy to understand

since the system is to be used in an educational purpose. Much time has been spent impedance

matching components, a task that proved to be harder than we expected. Other work that has been

is layout of all parts, filter construction and the writing of an easy to understand thesis. After the

parts had been completed, they were tested in a network analyzer and/or spectrum analyzer.

Successful full system test has been done up to 400 meters, the length the system is to be used

for.

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Rasheed, Maaz. "C Band Microwave Oscillator." Thesis, University of Gävle, University of Gävle, Department of Technology and Built Environment, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-3002.

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The work focuses on the study, design and implementation of a C band Microwave oscillator using coaxial resonators, for the transceiver used in wave radar. It involves a literature study discussing different aspects of microwave oscillators, mainly the shielding of the oscillators, frequency pulling due to load and supply pulling, tuning range and the temperature performance of the oscillator. The study of the shielding resulted in proposing a high quality metallic shield with high elastic modulus, high strength and high density, as the wave radar will be a stationary, standalone system and the weight of the shield is not a limiting factor. The metallic shield provides better EMI and EMP performance than the carbon ferrites. The characterization of the resonator is critical as a small mistake pulled the frequency about 300 MHz. This can be achieved by careful design and measuring the resonator test circuits for one port. The tuning range of the oscillator is important as the temperature, bias, and load mismatches can increase or decrease the frequency of the oscillator. The varactor in combination with a capacitor increases the tuning range to about 10 times. The high reverse isolation of 47 dB is achieved by a passive attenuator and a buffer amplifier. The temperature performance is also important and there was a 30 MHz variation in frequency from 0-60 degree centigrades, and the output power was between 3-4 dBm. The Load puling was 1 MHz with a 12 dB return loss test setup for a phase change of 0-180 degrees. The phase noise was -98 dBc/Hz at 100 kHz offset. Overall the coaxial resonator oscillator proves to be a very good stable oscillator suitable for aerospace and ground based industry.

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Desai, Bimbisar. "Microwave assisted organic synthesis." Thesis, University of Surrey, 2002. http://epubs.surrey.ac.uk/842821/.

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The area of chemical research and synthesis increasingly recognises the need for improved technologies and methods, which involves chemical processes with less energy consumption, time savings, reduction and/or minimisation of waste, simple processes and an overall clean production. Microwave heating has been exploited in a variety of disciplines for many useful applications and organic synthesis is an area, which has benefited significantly over the past decade. The present study investigates organic reactions accelerated under microwave irradiations. In particular, the study involves use of recyclable Polymer and Inorganic Solid Supported Reagents for application in transfer hydrogenation. Reductions of electron deficient alkenes have been studied using polymer and inorganic solid supported formates. Microwave irradiations have been used to study transfer hydrogenations in presence of Wilkinson's catalyst [RhCl(PPh3)3]. The application of the Polymer Supported Reagents (PSR) has been investigated for studying transfer hydrogenation in N-benzyl deprotections. Microwave assisted synthesis of formamides from primary and secondary amines have been studied using supported formates. Microwave irradiations have also been applied in studying heterocycle synthesis by cycloaddition of nitrones with Pt (II) and Pd(II) bound organonitriles. The study broadly demonstrates a means of simplifying reaction procedures and purification along with reduction in waste of reagents and release of toxic residues. More importantly, use of microwave irradiations has been used to substantially improve the reaction yields and reduce reaction times, lower energy consumption and solvent volumes. The use of this methodology significantly benefits in the development of "Green Chemistry" and automated systems for chemical synthesis in many industrial sectors.

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Légère, Jean-Guy Joseph. "Capsule-based microwave digestion." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39940.

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A large tube microwave digestion system with capsule sample introduction has been developed. This is the first automatic pressurized microwave digestion system to use: (1) capsule sample introduction, (2) reagent addition, and (3) controlled venting, during a digestion. The digestion tube has built-in cooling, an infrared temperature sensor, an in-line pressure sensor, automatic venting, and a new type of valve, called the "Flange Valve". The flange valve was designed for loading capsules into the digestion tube and for easy cleaning of all valve and tube parts wetted by the sample.
The digestion tube is made of Teflon PFA$ sp circler,$ which is capable of operating at 200 psi and 200$ sp circ$C. Water, salt solutions, and concentrated nitric acid were used to characterize the system.
A process was developed to make capsules from ultra-clean polyacrylamide gel; it was used to make capsules for the analysis of soils, botanicals, and biological samples. A "Squeegee", a device equipped with a soft, gas-tight Teflon$ sp circler$ end pushed through the digestion tube with a flexible rod, was used to insert capsules into and remove digestate from the digestion tube.
Micro2, an interpretive language, written in-house, uses English-like instruction files to control the digestion. Micro2 uses pressure, temperature and time data to control venting, cooling, and heating during the digestion. Triggers and feedback loops in the instruction file allow Micro2 to adapt to changing conditions in the digestion tube to complete a digestion without loss of analyte.
Analysis of the digested samples revealed that, for the same digestion temperature, dissolution is identical to that performed in a conventional microwave bomb.

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Waymont, David Keith. "Observing the microwave background." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303144.

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Rowe, David James. "Microfluidic microwave resonant sensors." Thesis, Cardiff University, 2012. http://orca.cf.ac.uk/39364/.

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Matter can be identified by its interaction with electromagnetic fields. This can be described by its dielectric and magnetic properties, which typically vary with respect to frequency in the microwave region. Microwave-frequency spectroscopy is capable of making non-contact, non-destructive, non-invasive and label-free measurements with respect to time. It can be used to characterise all states of matter and combinations thereof, such as colloids and microparticulate suspensions. Sensors based upon this technology therefore have great potential for (bio)chemical and industrial point-of-sampling applications where existing measurement techniques are insufficiently portable, low-cost or sensitive. Microfluidics is the manipulation of fluids within microscale geometries. This gives rise to phenomena not observed at the macroscale that can be exploited to achieve enhanced control of fluid flow. This means that microfluidic techniques can be used to perform complex chemistry in a completely sealed environment with minimal reagent consumption. Hence, microfluidics offers an ideal sample interfacing method for a microwave-frequency sensor. This work is concerned with developing novel, low-cost and highly sensitive probes that be easily integrated into a microfluidic device for performing on-chip sample preparation and diagnostics for generic (bio)chemical and industrial point-of-sampling applications. To this end, several novel microwave resonant structures were designed, optimised and integrated into microfluidic devices in order to characterise a variety of liquid-phase samples.

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Wong, Peng Wen. "Electronically reconfigurable microwave filter." Thesis, University of Leeds, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.507875.

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Hulsey, Robert W. "Multiple frequency microwave ablation." Thesis, Mississippi State University, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1586972.

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In recent years, microwave ablation therapy has become widely investigated as an alternative treatment to cancer. This method is one of the newest forms of ablation techniques for the removal of tumors and is minimally invasive compared to alternative treatments. One drawback to many of the current microwave ablation systems is the narrowband nature of the antennas used for the probe, such as dipole antennas. This study aims to compare ablation results of both ultra-wideband and narrowband ablation techniques. An ultra-wideband ablation probe is designed that operates from 400MHz to 2.6GHz and are compared to two designed narrowband ablation probes that operate at 915MHz and 2.4GHz, respectively. These ablation probes are tested in tissue mimicking gels and porcine liver. Provided results for this thesis will include probe designs, simulation results, and ablation experiments.

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Moh, Sarfaraz. "Microwave assisted sputtered coatings." Thesis, University of the West of Scotland, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.556071.

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Barrett, C. P. "Optical-microwave double resonance." Thesis, University of East Anglia, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355527.

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Ushiroda, Shin. "Microwave photoelectrochemistry of silicon." Thesis, University of Bath, 2002. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.760782.

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Konpang, Jessada. "Microwave interference cancellation system." Thesis, University of Leeds, 2018. http://etheses.whiterose.ac.uk/20546/.

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A microwave interference cancellation system is presented in this thesis. The technique achieves high Tx/Rx isolation with relatively low degree filters. A four-port diplexer consists of two back-to-back three-port diplexers combined with a 180° phase shift in one branch. High signal isolation between Tx and Rx module is achievable by only using second-order filter topology and the design technique is based on amplitude and phase cancellation between two diplexer branches of the four-port diplexer. Three and four-port networks are intensively analysed and synthesised for solving S-parameter equations. The four-port diplexer exploits the microstrip open-loop structure. A four-port microstrip diplexer for RF interference rejection is presented in IMT-2000 applications whereas device miniaturisation and low infrastructure cost are required. The microstrip-open loop structure with coupled-feed and tapped-feed are designed for alternative techniques and cost reduction. A 180° phase shift in one branch can be achieved by delayed transmission line. The simulated microstrip four-port network is designed at the centre frequency of Tx/Rx at 1.95 GHz and 2.14 GHz, respectively. An alternative technology to reduce overall signal losses and increase power handling with the same or better isolation compared to the four-port microstrip technology is four-port combline coaxial resonator structures. To achieve filter design with a 180° different phase shift, the positive (90° inverter) and negative (-90° inverter) coupled filters are required. The design frequencies of the four-port combline diplexer are 1.73 GHz and 2.13 GHz for Rx and Tx modules, respectively. Two different designs of four-port diplexer prototypes, based on filter designs with similar and dissimilar Q-factors, are fabricated and measured to verify the new design technique. Finally, microwave interference cancellation techniques can be used in wireless communication systems where small size, low losses and low complexity are required.

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37

Hansson, Lars. "Microwave treatment of wood." Doctoral thesis, Luleå tekniska universitet, Träteknologi, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26364.

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Drying wood using microwave energy is not very common, but could be a complement to conventional air-circulation drying due to the possibility to dry wood faster than the conventional drying methods with preserved quality. Furthermore, this technique could be used to condition boards with too high moisture content gradient. In this study, an industrial-scale, online microwave drier for wood components has been used and adapted to wood treatment. The aim of the present work was to investigate if the microwave drying method itself affects such wood properties as bending strength, hardness and colour change. Another aim was to explain, with finite element model simulations, the interaction between microwaves and wood during heating and drying and to a lesser extent also during microwave scanning of wood. Tests of the mechanical properties of wood showed no difference in bending strength in comparison with the conventional air circulation method. Nor was there any significant difference in wood hardness (Janka) perpendicular to the grain between the drying methods or between different temperature levels during the microwave drying. However, the results showed that there is a significant difference in wood hardness parallel to the grain between the methods when drying progressed to relatively lower levels of moisture content; i.e. wood hardness becomes higher during microwave drying. The developed multiphysics finite element model is a powerful evaluation tool for understanding the interaction between wood and microwaves during heating and drying as well as scanning. The model can be used for simulation of different microwave treatments of wood.
Godkänd; 2007; 20071015 (ysko)

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38

Tho, Lee-Lee. "Microwave spectroscopy of pentafluorosulfanylisocynate." Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/94478.

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The microwave spectrum of pentafluorosulfanylisocyanate, SF₅ -N = C = 0 has been investigated in the 8 GHz to 26 GHz region using a conventional Stark modulated spectrometer. Twenty six transitions have been assigned. A rigid rotor fit was performed by using low J transitions. The spectroscopic constants obtained are A = 2707.69 MHz, B = 1191.22 MHz, and C = 1191.13 MHz. These constants are close to those determined by the electron diffraction study on pentafluorosulfanylisocyanate and to this extent tend to support the bent -N = C = 0 structure as proposed by the electron diffraction study.
M.S.

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39

Folorunso, Olaosebikan. "Microwave processing of vermiculite." Thesis, University of Nottingham, 2015. http://eprints.nottingham.ac.uk/28802/.

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Vermiculite is a clay mineral that is generally used for a wide range of applications such as in agricultural, horticultural and construction industries. This is due to its various properties which include high porosity, lightweight, thermo-insulating, non-toxic and good absorption capacity when exfoliated. The objective of this research was to critically evaluate the fundamental interaction of electromagnetic waves with vermiculite from different source locations and to understand the mechanism of exfoliation in an applied microwave field. When vermiculite minerals are placed under the influence of high electric fields, they expand due to the rapid heating of their interlayer water, which subsequently builds up pressure that pushes apart the silicate structure. The degree of exfoliation is directly related to the intensity of the applied electric field. The principal areas covered in this thesis include: a detailed review of the fundamentals of microwave processing and issues surrounding scale up; a critical literature review of vermiculite mineralogy, and previous methods of vermiculite processing and their limitations; understanding the interaction of microwave energy with vermiculite by carrying out mineralogical and dielectric characterisation; microwave exfoliation tests of vermiculite minerals from different source locations and a comparative energy and life cycle analysis of microwave and conventional exfoliation of vermiculite. A detailed review of the literature revealed that conventional exfoliation of vermiculite by gas or oil fuelled furnaces has significant limitations such as emissions of greenhouse gases, high-energy requirements (greater than 1 GJ/t), health and safety issues and poor process control. All work reported so far on microwave exfoliation of vermiculite has been limited to laboratory scale using domestic microwave ovens (2.45 GHz, power below 1200 W) and the route to scale up the process to industrial capacity has not given due consideration. Mineralogical characterisation of vermiculite from different geographical locations (Australia, Brazil, China and South Africa) revealed that only the sample from Brazil is a pure form of vermiculite while the other samples are predominantly hydrobiotite. All the samples have varying degrees of hydration with the Brazilian sample having the highest total water content. The presence of water in any form in a material influences its dielectric response and ultimately the microwave absorbing properties. The dielectric characterisation carried out on the different vermiculite samples shows that the vermiculite mineral structure is effectively transparent to microwave energy, but it is possible to selectively heat microwave absorber, which is the interlayer water in the vermiculite structure. The continuous microwave exfoliation tests carried out at both pilot scale at 53-126 kg/h and the scaled up system at 300-860 kg/h demonstrated that microwave energy can be used for the industrial exfoliation of vermiculite at high throughputs and is able to produce products below the specified product bulk densities standard required by The Vermiculite Association (TVA). The degree of vermiculite exfoliation depends on factors such as power density, feedstock throughput, energy input, interlayer water content, particle size of the feedstock, and vermiculite mineralogy. The highest degree of exfoliation was recorded for the Brazilian sample, which also had the highest water content. Life cycle analysis (LCA) frameworks by the International Organisation for Standardisation (The ISO 14040: principles and framework and ISO 14044: Requirements and guidelines) and British standards institution (PAS2050) were used to carry out comparative life cycle analysis of vermiculite exfoliation using microwave heating and conventional (industrial and Torbed) heating systems. The results showed that the microwave system potentially can give an energy saving of about 80 % and 75 % over industrial and Torbed Exfoliators respectively, and a carbon footprint saving potential of about 66 % and 65 %. It can be concluded that the reduced dust emission and noise from the microwave system would improve the working conditions, health and safety. Furthermore, the methodology discussed in this project can be used to understand the fundamental of microwave interaction with perlite and expanded clay, which are minerals with similar physical and chemical compositions as vermiculite.

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40

Mazin, Benjamin A. Ellis Richard S. "Microwave kinetic inductance detectors /." Diss., Pasadena, Calif. : California Institute of Technology, 2005. http://resolver.caltech.edu/CaltechETD:etd-10042004-120707.

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41

Wang, Xudong. "Microwave Photonic Signal Processing." Thesis, The University of Sydney, 2013. http://hdl.handle.net/2123/10087.

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A new single-wavelength coherence-free microwave photonic notch filter is presented. The concept is based on a dual Sagnac loop structure that functions with a new principle in which the two loops operate with different free spectral ranges. Experimental results demonstrate a notch filter with a narrow notch width, a flat passband, and high stopband attenuation of over 40 dB. A new multiple-tap microwave photonic notch filter structure that can simultaneously realise a frequency-independent group delay together with a narrow notch filter response and large free spectral range is presented. The concept is based on using multiple wavelengths circulating in a Sagnac loop. Experimental results demonstrate a notch filter with a flat passband, a narrow notch width, a high rejection level of over 40 dB, and an extremely low group delay ripple of less than ±25 ps. A new photonic microwave phase shifting structure that can realise a continuous 0o to 360o phase shift with only little frequency dependent amplitude and phase variation over a wide frequency range is presented. It is based on controlling the wavelengths of two phase modulated optical signals into an optical filter with a nonlinear phase response. The new photonic microwave phase shifter has been experimentally verified showing the continuous 0o to 360o phase shifting operation with less than 3 dB amplitude variation over a wide frequency range. A new microwave photonic phase shifter structure is presented. It is based on the conversion of the optical carrier phase shift into an RF signal phase shift via controlling the carrier wavelength of a single-sideband RF modulated optical signal into a fibre Bragg grating. Experimental results demonstrate a continuous 0o to 360o phase shift with low amplitude variation of < 2 dB and low phase deviation of < 5o over a wideband microwave range.

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42

SIMONE, MARCO. "Optimization of microwave devices." Doctoral thesis, Università degli Studi di Cagliari, 2016. http://hdl.handle.net/11584/266750.

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This thesis deals with the optimization techniques for the improvement of the microwave devices performance. In particular, the technique proposed considers the Particle Swarm Optimization algorithm and applies such an algorithm to different devices. Different techniques are developed to connect the optimization with an electromagnetic analysis tool. In the first method the algorithm has been connected to a numerical technique for the evaluation of the device performance (FDFD). The second technique consists on the integration of the algorithm with a 3D Simulation CAD (HFSS, CST). The microwave devices under test are a ridge waveguide (in different configurations), a resonant cavity, a waveguide impedance transformer and an electromagnetic band gap structure. Both the approaches result to be effective for the purpose even in the event that a constraint between conficting requirements is requested.

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43

Habash, Riadh W. Y. "Non-Invasive Microwave Hyperthermia." Thesis, Indian Institute of Science, 1994. https://etd.iisc.ac.in/handle/2005/193.

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Presented in this thesis are the following theoretical investigations carried out on the non-invasive microwave hyperthermia of malignant tumours in the human body: Fundamental concepts of electromagnetic wave propagation through a biomass and its interaction with it, are discussed. Various types of applicators used for producing hyperthermia in a biomass, are also discussed. Propagation of a uniform plane electromagnetic wave through a human body is investigated for the general case of oblique incidence. Various models used for the human body have been discussed and the planar multilayer model has been chosen for this study. Reflection and transmission coefficients for both the parallel and perpendicular linear polarisations of the wave, have been determined. For normal incidence, power transfer ratio at the muscle has been defined and calculated at 433, 915 and 2450 MHz (ISM frequencies). Efects of skin thickness and also of fat thickness, on the power transfer ratio at muscle, have been studied. Effects of the thickness and dielectric constant of a bolus, and also of the dielectric constant of an initial layer, on the power transfer ratio, have been studied and their optimum values obtained at the ISM frequencies. For microwave hyperthermia, 915 MHz is recommended as the frequency of operation. Steady-state solution of the bioheat transfer equation has been obtained, assuming the biomass to be a semi-infinite homogeneous medium. Effects of various physical parameters on the temperature profile in the biomass, have been studied. Also studied is the effect of the surface temperature on the magnitude, location and the width of the temperature peak attained in the biomass. A method to determine the microwave power and the surface temperature required to produce a prescribed temperature profile in the biomass, has been developed. The transient-state solution of the bioheat transfer equation has been obtained to study the building up of the temperature profile. Procedures for the design of an open-ended rectangular metal waveguide applicator and for estimating the total microwave power requirement to produce hyperthermia in the human body, have been developed. Performance of the applicators employing linear as well as planar arrays of open-ended rectangular metal waveguide antennas, has also been studied. In order to reduce the overall physical size of the applicators, filling up of the feed waveguide with a high dielectric constant but low loss material is suggested. A simple method of obtaining the elements of the array by partitioning a large aperture by using metal walls has been adopted. Calculation of the total microwave power required by various applicators for producing hyperthermia at various depths in a biomas, have been made and a comparison of the performance of various applicators, has been presented.

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44

Habash, Riadh W. Y. "Non-Invasive Microwave Hyperthermia." Thesis, Indian Institute of Science, 1994. http://hdl.handle.net/2005/193.

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Presented in this thesis are the following theoretical investigations carried out on the non-invasive microwave hyperthermia of malignant tumours in the human body: Fundamental concepts of electromagnetic wave propagation through a biomass and its interaction with it, are discussed. Various types of applicators used for producing hyperthermia in a biomass, are also discussed. Propagation of a uniform plane electromagnetic wave through a human body is investigated for the general case of oblique incidence. Various models used for the human body have been discussed and the planar multilayer model has been chosen for this study. Reflection and transmission coefficients for both the parallel and perpendicular linear polarisations of the wave, have been determined. For normal incidence, power transfer ratio at the muscle has been defined and calculated at 433, 915 and 2450 MHz (ISM frequencies). Efects of skin thickness and also of fat thickness, on the power transfer ratio at muscle, have been studied. Effects of the thickness and dielectric constant of a bolus, and also of the dielectric constant of an initial layer, on the power transfer ratio, have been studied and their optimum values obtained at the ISM frequencies. For microwave hyperthermia, 915 MHz is recommended as the frequency of operation. Steady-state solution of the bioheat transfer equation has been obtained, assuming the biomass to be a semi-infinite homogeneous medium. Effects of various physical parameters on the temperature profile in the biomass, have been studied. Also studied is the effect of the surface temperature on the magnitude, location and the width of the temperature peak attained in the biomass. A method to determine the microwave power and the surface temperature required to produce a prescribed temperature profile in the biomass, has been developed. The transient-state solution of the bioheat transfer equation has been obtained to study the building up of the temperature profile. Procedures for the design of an open-ended rectangular metal waveguide applicator and for estimating the total microwave power requirement to produce hyperthermia in the human body, have been developed. Performance of the applicators employing linear as well as planar arrays of open-ended rectangular metal waveguide antennas, has also been studied. In order to reduce the overall physical size of the applicators, filling up of the feed waveguide with a high dielectric constant but low loss material is suggested. A simple method of obtaining the elements of the array by partitioning a large aperture by using metal walls has been adopted. Calculation of the total microwave power required by various applicators for producing hyperthermia at various depths in a biomas, have been made and a comparison of the performance of various applicators, has been presented.

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45

Bayramoglu, Beste. "Solvent-free Microwave Extraction And Microwave-assisted Hydrodistillation Of Essential Oils From Spices." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/2/12608874/index.pdf.

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ABSTRACT SOLVENT-FREE MICROWAVE EXTRACTION AND MICROWAVEASSISTED HYDRODISTILLATION OF ESSENTIAL OILS FROM SPICES Bayramoglu, Beste M.S., Department of Food Engineering Supervisor: Assoc. Prof. Dr. Serpil Sahin Co-Supervisor: Assoc. Prof. Dr. S. Gü
lü
m Sü
mnü
September 2007, 130 pages The undesirable effects of conventional methods generated the need for economical and safe techniques in the extraction of essential oils. Microwave-assisted hydrodistillation (MAHD) and solvent-free microwave extraction (SFME) are recently developed techniques, which are thought to overcome this problem. Oregano (Origanum vulgare L.), laurel (Laurus nobilis L.) and rosemary (Rosmarinus officinalis L.) were chosen in this study since they have high antimicrobial and antioxidant effects and are widely grown and consumed in Turkey. The objectives of this study were to examine the applicability of SFME in the extraction of essential oils from oregano and laurel, and MAHD in the extraction of rosemary essential oil. The effects of microwave power and extraction time on the yield, composition, and other quality parameters of the extracts were also investigated. Hydrodistillation was performed as control. SFME offered significantly higher essential oil yields (0.054 mL oil/g oregano) from oregano as compared to hydrodistillation (0.048 mL oil/g oregano). Conventional process time was reduced by 80%. Main aroma compound was thymol (650-750 mg thymol/mL oil). For laurel, no significant differences were obtained in yields (about 0.022 mL oil/g laurel) obtained by SFME and hydrodistillation. Process time was reduced by 55-60%. Main aroma compound was 1,8-cineole (630-730 mg 1,8-cineole/mL oil). In the case of rosemary, no significant differences were obtained in yields (about 0.026 mL oil/g rosemary) obtained by MAHD at 622 W and hydrodistillation. The process time was reduced by about 65%. Main aroma compounds were 1,8-cineole (430-500 mg 1,8-cineole/mL oil) and camphor (150-210 mg camphor/mL oil). Keywords: Solvent-free microwave extraction (SFME), Microwave-assisted hydrodistillation (MAHD), Origanum vulgare L., Laurus nobilis L., Rosmarinus officinalis L.

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46

Kniveton, Dominic. "Monitoring global precipitation using passive microwave data from the special sensor microwave/imager." Thesis, University of Bristol, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259560.

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47

Robb, Graeme R. "The microwave effect : non-thermal effects of microwave radiation in solid state chemistry." Thesis, University of Edinburgh, 2005. http://hdl.handle.net/1842/11895.

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Microwaves are commonly used for a number of solid state reactions, including sintering of ceramics, drying of materials and ionic substitution reactions. It is for such solid state processes that some of the most interesting effects are observed; yet these are presently amongst the most poorly understood. Diffraction is arguably the most incisive technique for the probing of solid state processes. To observe specific effects of microwave radiation it is necessary to perform in-situ diffraction experiments. Here we detail microwave applicators, modified for such a purpose. Simple phenomena, such as thermal expansion and phase transitions were observed for diverse materials (aspirin, silver iodide, β-alumina and barium titanate) under the influence of microwave heating. Furthermore, the use of w-situ diffraction as a method of temperature measurement is investigated. Some of these materials show unexpected effects when heated with microwaves, including anomalously large thermal expansion, the lowering of the phase transition temperature and a reduction in atomic displacement parameters. A consistent model has been proposed to explain these effects in terms of interactions of the electric field with a low-energy transverse optic phonon mode. The model only applies to materials possessing such a mode and no anomalous effects are observed otherwise. Barium titanate is a seemingly more complicated material and a strong electron-phonon interaction, resulting in local ordering may account for further anomalies. Another application of microwaves is the synthesis of nanoparticles using a microwave-induced plasma. This is an established technique, yet its application is limited to species with a volatile precursor. Here we extend the technique and design apparatus for use with a precursor in an aerosol, allowing the use of non-volatile, cheap precursor compounds.

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48

Thakare, Aditya. "A Study of Microwave curing of Underfill using Open and Closed microwave ovens." PDXScholar, 2015. https://pdxscholar.library.pdx.edu/open_access_etds/2246.

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As the demand for microprocessors is increasing with more and more consumers using integrated circuits in their daily life, the demand on the industry is increasing to ramp up production. In order to speed up the manufacturing processes, new and novel approaches are trying to change certain aspects of it. Microwaves have been tried as an alternative to conventional ovens in the curing of the polymers used as underfills and encapsulants in integrated circuits packages. Microwaves however being electromagnetic waves have non uniform energy distribution in different settings, causing burning or incomplete cure of polymers. In this study, we compare the two main types of microwaves proposed to perform the task of curing the polymers. To limit the study and obtain comparable results, both microwaves were limited to propagate in a single mode, TE10. The first is a closed microwave cavity using air as the propagation medium, and the second is an open microwave oven with a PTFE cavity that uses an evanescent field to provide energy. The open air cavity was studied with different orientations of a substrate placed inside it so as to find the best case scenario in the curing process. This scenario was then compared with the best case scenario found for a sample cured in an evanescent field. This comparison yielded results showing an advantage of the open microwave in maximum field present, thus leading to higher localized energy absorption and temperatures in the substrate, however this case also lead to a higher temperature gradient. The substrate cured in the closed microwave has a lower temperature gradient, but also a lower maximum field which leads to slower cure. In the TE10 mode therefore, a closed microwave has an overall advantage as the heating process is only slightly slower than that of an open cavity, but the temperature gradient in this case is significantly lower.

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Jordan, Jennifer L. "Contactless Radio Frequency Probes for High Temperature Characterization of Microwave Integrated Circuits." Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1402066531.

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Laureano, Marilou L. "Developments in microwave and infạred technologies temperature and moisture measurements in food systems." Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61894.

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Dissertations / Theses on the topic 'Microwave'

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