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1
Khattak, Muhammad I. "Microwave measurement techniques for wearable antennas." Thesis, Loughborough University, 2010. https://dspace.lboro.ac.uk/2134/6454.
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This research is germane to the area of on-body antennas and the characterisation of antennas in close proximity to biological matter. The ranges of frequencies discussed are currently popular for mobile communications, namely 0.9GHz to 6GHz with spot frequencies of GSM900, GSM1800 and WiFi2.5GHz. Particular attention is given to the elimination of errors in measurement. This is achieved by the characterisation of an anechoic chamber; a study of the effects of cables; a study of the interaction of surface currents and the human body; a study of tissue simulating liquid; the design of a simple body phantom; the characterisation of the on-body channel for human males in wet and dry clothing and a comparison of perturbation on antennas close to humans and a phantom.
2
Gau, Jiahn-Rong J. "Microwave absorber analysis, design and measurement /." The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487859313347128.
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Williams, Wyman L. Rutledge David B. Rutledge David B. "Computer-aided measurement of microwave circuits /." Diss., Pasadena, Calif. : California Institute of Technology, 1989. http://resolver.caltech.edu/CaltechETD:etd-02162007-080706.
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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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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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Statz, C., J. Küttner, D. Plettemeier, and Thomas Herlitzius. "SEBIMO - Microwave-based Measurement of Soil Parameters." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-229895.
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Mercer, Sean R. "Online microwave measurement of complex dielectric constant." Doctoral thesis, University of Cape Town, 1990. http://hdl.handle.net/11427/8342.
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Includes bibliographical references.This dissertation examines the problem of on-line measurement of complex dielectric constant for the purpose of dielectric discrimination or product evaluation using microwave techniques. Various methods of signal/sample interaction were studied and consideration was given to the problem of sorting irregularly shaped discrete samples. The use of microwave transmission and reflection measurements was evaluated. The signal reflection methods were deemed to be best suited to applications with constant geometry feed presentation ( ie. a continuous, homogeneous product stream with little variation in surface geometry).
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Isa, Maryam Binte Mohd. "Microwave radar sensor for solid flow measurement." Thesis, University of Manchester, 2006. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.488369.
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Industrial flow measurement is a challenging area and in high demand. Tremendous research has been carried out to improve and solve problems in the flow measurement system. Thus, new techniques are produced and a wider range of flow measurement solutions have become available in market. This study has introduced a new technique that is useful and proves to be applicable in industrial flow measurement system. Microwave Doppler radar sensor was used to extract useful information of the solid flow characteristics. The amplitude level of the Doppler signal is analysed instead of the frequency shift that is normally used in conventional Doppler radar sensor. The relation between the amplitude level and the characteristic of the flow was determined to define the characteristics of the flow. The solids weight and dimension are among the characteristics that are investigated in this study. Microwave sensor circuits based on Doppler radar technique operating at 2.45GHz and 10.58GHz were designed, constructed and tested. The 2.45GHz system was built in the initial study and pre-testing of the Doppler radar sensor system prior to the construction of the 10.58GHz system that was later used for the measurement purposes. The antennas and circuit analyses were carried out in building an optimum sensor system. Two-antenna and two-antenna with copper plate are two new antenna configurations that are applied in single solid flow measurement analysis. The flow measurements were carried out using different types of solids ranges from 4mm to 20mm sizes and 0.02g to 0.63g of weight for single and multiple solids flow. The linear relations of the reflected power and the solids characteristics determined from the analyses are found to be useful in differentiating the type of solids and measuring the total weight of solids flowing.
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Louw, Willem J. "Microwave heating of multiphase materials : modelling and measurement." Thesis, Stellenbosch : Stellenbosch University, 2005. http://hdl.handle.net/10019.1/21217.
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Thesis (MScIng)--University of Stellenbosch, 2005.ENGLISH ABSTRACT: Both coaxial probe and waveguide (WG) measurement systems for electric and magnetic material property extraction were investigated. These measurement techniques were used to determine electrical properties of an inhomogeneous rock sample in its solid and crushed states. A lumped element model of the probe was used and permittivity was determined by the inversion algorithm developed by Stuchly and Stuchly. To support this technique it was compared to a full wave inversion algorithm and referenced to properties of the same samples but determined by a resonant cavity technique. The Nicholson, Ross and Weir inversion algorithm was used to determine material properties from WG measurements. As a reference, the same techniques were applied to a well defined material. It was found that neither of the measurement techniques could measure low loss factors or conductive materials and literature values were used in these cases. Various simulation models of the multiphase ore in both its solid and crushed states are presented. These models were utilised in finite-difference time-domain (FDTD) simulations of different microwave (MW) cavities. Simulation and experimental S-parameter comparisons are presented. The level of accuracy achieved varies as a function of the geometrical representation and material properties. After an S-parameter comparison with simulation results it was concluded that the electrical properties of both the solid and crushed rocks have been well determined for MW cavity design. Predicted and measured field distributions in cavities were also compared and it is shown that accurate models of multiphase materials become especially important in the determination of field distributions in and around different rock phases. Recommendations for the suggested material property determination and verification processes are presented. A specific application of this work is in the field of microwave assisted comminution.
AFRIKAANSE OPSOMMING: ’n Koaksiale probe en golfgeleier (WG) stelsels vir die bepaling van materiaal eienskappe (elektries en magneties) word gebruik met die doel om ’n nie-homogene rotsmonster te karakteriseer. Die ekstraksie algoritme van Stuchly en Stuchly word gebruik om die materiaal eienskappe te bepaal vanaf die gemete S11-parameter. Hierdie ekstraksie metode word vergelyk met ’n vol golf ekstraksie van permitiwiteit vanaf dieselfde gemete data. Beide die ekstraksie metodes word dan vergelyk met resonante holte meetings van dieselfde materiale. Die Nicholson, Ross en Weir ekstraksie algoritme word toegepas op meetings wat gedoen is deur die golfgeleier stelsel. As ’n verwysing word dieselfde tegnieke toegepas op ’n bekende materiaal en daar is gevind dit stem goed ooreen behalwe dat nie een van die twee meet tegnieke lae verlies faktore kan meet nie. Verder kan nie een van die twee sisteme geleidende materiale meet nie. Vir sulke gevalle is waardes nageslaan. Verskeie simulasiemodelle van die rots word voorgestel vir beide soliede en vergruisde monsters. Hierdie modelle word gebruik in FDTD simulasies van verskeie mikrogolftoevoegers met die oog om ’n vergelyking te tref tussen gesimuleerde en gemete S-parameters. Verskillende vlakke van akkuraatheid is bereik en is ’n funksie van die geometrie en die materiaaleienskappe van die model. Nadat gemete en gesimuleerde S-parameters vergelyk is, is gevind dat die materiaal eienskappe van beide die soliede en vergruisde rots monsters goed bepaal is vir mikrogo lf toevoeger ontwerp. Voorspelde en gemete veldverspreidings word ook vergelyk en dit is veral hierso van belang om ’n realistiese model van die nie-homogene monster te gebruik. Sekere voorstelle word gemaak om die verskillende aspekte van die meet van ma teriaaleienskappe en simulasiemodelle te kan verfyn. ’n Spesifieke toepassing van hierdie werk is in mikrogolf ondersteunde skeiding van minerale en erts.
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Amiet, Andrew. "Free space permittivity and permeability measurements at microwave frequencies." Monash University, Dept. of Electrical and Computer Systems Engineering, 2003. http://arrow.monash.edu.au/hdl/1959.1/9529.
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Lundgren, Nils. "Modelling microwave measurements in wood /." Luleå, 2005. http://epubl.luth.se/1402-1757/2005/61.
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Haigh, Arthur D. "A study of microwave moisture measurement in bulk materials." Thesis, Manchester Metropolitan University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387247.
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Moisture measurements play an important role in many material preparations and industrial processes. Microwave techniques have been used for several decades for such measurements. Shortcomings associated with the method have been addressed. Graphical solutions used hitherto to obtain the permittivity from waveguide measurements have been replaced by computer programs. The accuracy of measurement have been improved by the development of waveguide standards and the implementation of calibration procedures. Permittivity measurements in through and short circuited rectangular waveguides are reported on a wide range of solid, granular and liquid materials important to the food industry. Techniques to suppress standing wave effects have enabled accurate plane wave measurements of permittivity. For bulk materials, new measurement probes have been developed for on line measurements and associated with these probes lower cost instrumentation has been considered. The· main outcome of the study is the improvement in permittivity measurements of sample quantities of material. Moisture measurements in bulk materials have been facilitated by novel non invasive probes.
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Petrović, Nikola. "Measurement System for Microwave Imaging Towards a Biomedical Application." Doctoral thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-24878.
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Microwave imaging techniques have shown excellent capabilities in various fields such as civil engineering, nondestructive testing, industrial applications, and have in recent decades experienced strong growth as a research topic in biomedical diagnostics. Many research groups throughout the world work on prototype systems for producing images of human tissues in different biomedical applications, particularly breast tumor detection. However, the research community faces many challenges and in order to be competitive to other imaging modalities one of the means is to put emphasis on experimental work. Consequently, the use of flexible and accurate measurement systems, together with the design and fabrication of suitable antennas, are essential to the development of efficient microwave imaging systems. The first part of this thesis focuses on measurement systems for microwave imaging in terms of antenna design and development, robot controlled synthetic array geometries, permittivity measurements, and calibration. The aim was to investigate the feasibility of a flexible system for measuring the fields around an inhomogeneous object and to create quantitative images. Hence, such an aim requires solving of a nonlinear inverse scattering problem, which in turn requires accurate measurements for producing good quality experimental data. The presented solution by design of a flexible measurement system is validated by examination of microwave imaging from experimental data with a breast phantom. The second part of the thesis deals with the research challenges of designing high performance antennas to be placed in direct contact with or in close proximity to the imaged object. The need for novel antenna applicators is envisaged in the framework of the Mamacell measurement system, where the antenna applicators have to be designed and constructed to effectively couple the energy into the imaging object. For this purpose the main constraints and design requirements are a narrow lobe of the antenna, very small near-field effects, and small size. Numerical simulations and modeling shows that the proposed ridged waveguide antenna is capable of fulfilling the design requirements and the performance goals, demonstrating the potential for the future microwave imaging system called Mamacell.
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Cholerton, Simon Derrick. "Microwave measurement of single crystals of high temperature superconductors." Thesis, University of Cambridge, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319565.
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Hubbard, Amanda Eileen. "Measurement of electron density on JET by microwave reflectometry." Thesis, Imperial College London, 1987. http://hdl.handle.net/10044/1/47392.
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Rimbi, Morris. "Wood microwave dielectric heating and measurement of material properties." Thesis, Stellenbosch : Stellenbosch University, 2004. http://hdl.handle.net/10019.1/50231.
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Thesis (PhD)--University of Stellenbosch, 2004.ENGLISH ABSTRACT: Microwave heating technology is extensively used in households, is well-established in certain industries and is being explored in others. lts attraction is that it is quick, energy efficient, clean and can be used to heat materials of both high and low thermal conductivities. Successful application of the technology requires knowledge of both material properties and microwave equipment. Commercial fixtures for measuring dielectric properties are not widely available and are usually created in-house. The domestic oven magnetron is easily available and can be used in prototype microwave systems but applicators for specific applications need development. This thesis covers three main areas, namely; dielectric measurement fixtures, microwave applicators and chokes, and drying of wood. The first part of the thesis presents four dielectric measurement fixtures, one commercial and the others in-house. The design and calibration of the in-house fixtures is presented. An intercomparison of the performance of the four fixtures is carried out by measuring the permittivities of well characterised dielectrics: teflon and perspex. The most convenient fixture is used to measure the dielectric properties of wood at different moisture contents. The second part covers the design of a slotted waveguide fed microwave applicator and a choke. The design of the slotted feed is carried out analytically with and without mutual coupling between the slots. A semi-empirical design using a finite element package is done independent of the analytical approach and the results are compared. The choke is rigorously characterised using a procedure which avoids de-embedding. The third and last section reports on the wood drying experiments carried out in the applicator, simulated and mapped heating patterns of drying wood, and a mock-up industrial wood drying facility.
AFRIKAANSE OPSOMMING: Mikrogolfverhittingstegnologie word wyd gebruik in huishoudings, is goed gevestig in sekere nywerhede en moontlike gebruike daarvan op ander gebiede word gedurig ondersoek. Die vernaamste voordele is dat dit vinnig, energiedoeltreffend en skoon is en dat dit gebruik kan word om materiale van beide hoë en lae termiese geleidingsvermoë te verhit. Suksesvolle toevoeging van die tegnologie vereis kennis van beide materiale-eienskappe en mikrogolftoerusting. Kommersiële apparaat vir die meet van diëlektriese eienskappe is nie wyd beskikbaar nie en word gewoonlik "binnenshuis" ontwikkel. Die huishoudelike mikrogolfoond magnetron is geredelik beskikbaar en kan in prototipe mikrogolfstelsels gebruik word, maar toevoegers geskik vir spesifieke gebruike moet ontwikkel word. Hierdie proefskrif dek drie hoofgebiede, naamlik: diëlektriese metingsapparaat, mikrogolftoevoegers en smoorders, en die droging van hout. Die eerste deel van die proefskrif handeloor vier diëlektriese metingsapparate, een kommersiëel en die ander "binnenshuis". Die ontwerp en kalibrasie van die "binnenshuis" apparate word aangebied. 'n Tussenvergelyking van die verrigtinge van die vier apparate word gedoen deur die meting van baie bekende diëlektrikums: teflon en perspex. Die mees gerieflike apparaat word gebruik vir die meet van die diëlektriese eienskappe van hout teen verskillend voginhoude. Die tweede deel dek die ontwerp van 'n smoorder en 'n mikrogolf toevoeger wat deur 'n gegleufde golfgeleier gevoer word. Die ontwerp van die gegleufde golfgeleier word beide met en sonder wedersydse koppeling tussen die gleuwe, analities gedoen. 'n Semi-empiriese ontwerp wat van 'n eindige-element pakket gebruik maak, is onafhanklik van die analitiese benadering gedoen. Die resultate word dan vergelyk. Die smoorder word deur 'n prosedure wat "de-embedding" vermy, streng gekarakteriseer. Die derde en laaste afdeling behandel die eksperimentele droging van hout binne die toevoeger. Simulasies en verhittingspatrone van die hout wat gedroog word, sowel as die "mock-up(model van die voorgestelde)" nywerheids houtdroogkamer, word gegee.
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Celliers, Scarre. "On-line moisture measurement of rocks, using microwave techniques." Master's thesis, University of Cape Town, 1989. http://hdl.handle.net/11427/8335.
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Includes bibliographical references.On-line measurement of the moisture content of process streams in a mineral processing plant is vital for their efficient operation. Although many industrial moisture meters are available, most of these were designed to determine the moisture content of low density, fine grained, uniformly surfaced and low resistance materials. Consequently these meters operate poorly on mineral treatment plants as the measured material, rock, is dense, uneven and consists of mixtures of various minerals. A literature survey revealed that of the many methods available, only three techniques could be used for on-line moisture determination in mineral processing operations.These were microwave attenuation, phase and frequency techniques.
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Hogan, Paul Francis John. "An Assessment Of Microwave Denture Processing By Temperature Measurement." Thesis, Faculty of Dentistry, 1989. http://hdl.handle.net/2123/4224.
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Sosa, Martin Daniel. "Software Automation For Measurement-Based Behavioral Models Of Microwave." Scholar Commons, 2009. https://scholarcommons.usf.edu/etd/30.
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This thesis presents a study and implementation of several measurement procedures used to efficiently generate non-linear measurement-based behavioral models primary for microwave amplifiers. Behavioral models are a solution for representing devices that can present linear and/or non-linear behavior when little or no information about the internal structure is known. Measurement-based behavioral models are an advantage since they can be extracted from a direct measurement of the device. This work addresses some of the challenges of these types of measurements. A set of software modules has been produced that combine several modern techniques to efficiently generate practical models using equipment commonly available in a typical microwave lab. Advanced models using new and more complex equipment are also discussed.
Modeling of the non-linear operation of power amplifiers is a common subject of study since it provides a path to improved system simulations. However, the measurement process used for non-linear behavioral modeling of PAs requires either non-linear measurement instrumentation, not yet widely available, or numerous measurements that makes the process tedious and susceptible to errors. Power dependent S-Parameters obtained with a conventional Vector Network Analyzers (VNA) can be used to extract AM-to-AM and AM-to-PM behavior of a device and to generate, simple but useful, behavioral models. A careful analysis of the characteristics of common RF measurement instrumentation combined with knowledge of common non-linear phenomena provides with the conditions under which useful models can be generated.
The results of this work are presented as several programs implemented in National Instruments LabVIEW that will sequence through the different measurements required for the generation of measurement-based behavioral models. The implemented models are known as P2D and S2D models available with Agilent Advanced Design System (ADS.) The code will communicate with the measurement instrumentation and decide on the most efficient way to extract the data. Once the data is extracted, the code will put into the appropriate syntaxes required by the model for direct and convenient setup of the generated models in ADS.
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Bunting, Jeremy. "The modelling and measurement of noise in microwave FET oscillators." Thesis, University of Leeds, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254670.
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Bakker, El-Sayed A. "Characterisation and measurement of non-linear systems in time domain." Thesis, University of Kent, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319232.
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Li, Qian. "Correlation between Simulation and Measurement of Microwave Resonator Power Handling." Thesis, Linköpings universitet, Fysik och elektroteknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-101981.
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In modern mobile wireless communication, Base Stations (BS) are the most important equipment to build up the mobile network. One of the key elements in BS is the RF filter, which plays a key role to secure the coverage and reliability of the BS. Especially, at Transmitter (Tx) side, the filter must have a high capability to handle the power sent from Power Amplifier (PA) to antenna in any circumstances to ensure the coverage demand. Otherwise, the breakdown will be encountered, setting the power flow in the BS system in an abnormal manner that, finally can lead to the shut down of BS or destroy the system permanently. In this project, three methods using two simulation tools to predict the power handling capability of the RF/microwave resonator which is the elementary component in the BS’s filter are proposed. Power handling tests of selected configurations corresponding to the simulations are implemented as well. In the next stage, the results from the prediction and measurement are compared. Finally, the conclusions of correlation between the prediction and measurement of microwave resonator power handling will be derived.
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Królak, Radoslaw [Verfasser]. "Investigation of field suitable microwave cavity measurement approaches / Radoslaw Królak." Aachen : Shaker, 2017. http://d-nb.info/1138177067/34.
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Odili, Daniel Ifesinachi. "Simulation and microwave measurement of the conductivity of carbon nanotubes." Thesis, University of Birmingham, 2011. http://etheses.bham.ac.uk//id/eprint/1335/.
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Recently, excellent properties have been realised from structures formed by carbon nanotubes. This propelled their use as nanoscale electronic devices in the information technology industry. The discovery of carbon nanotubes has stimulated interest in carbonbased electronics. Metal-Oxide-Semiconductor systems (MOS) are used to model charge transport within these carbon structures. Schrodinger‟s equation is solved self-consistently with Poisson‟s equation. The Poisson equation, which defines the potential distribution on the surface of the nanotube, is computed using a two-dimensional finite difference algorithm exploiting the azimuthal symmetry. A solution to the Schrodinger‟s equation is required to obtain the wavefunctions within the nanotube model. This is implemented with the scattering matrix method. The resulting wavefunctions defined on the nanotube surface are normalised to the flux computed by the Landauer equation. A novel implementation of the Schrodinger- Poisson solver for providing a solution to a three dimensional nanoscale system is described. To avoid convergence problems, an adaptive Simpson‟s method is employed in the model devices. Another main contribution to this field is the highlighting of the differences in the output characteristics of carbon nanotube- and graphene-based devices. In addition, the source and drain contacts that give an optimum device performance are identified. The limitation of this model is that quantised conductance appears on making contact to the nanotube ends. Electron transport in carbon nanotubes can be studied using non-contacting means. A new approach is to induce current in the nanotubes using microwave energy. A resonator-based measurement method is used to examine the electrical properties of the nanotubes. Remarkably, the nanotubes appear to have the smallest sheet resistance of any non-superconducting material. The possibility of a ferromagnetic carbon nanotube is investigated due to the remarkable screening properties observed. Measurements of the magnetisation as a function of the applied magnetic field are conducted using a vector vibrating sample magnetometer. The morphology and microstructure of the nanotubes are observed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. Carbon nanotubes can be contaminated with metal particulates during growth. These impurities can modify charge transport in these carbon structures.
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Lee, Shih-Fu. "Microwave measurement of Bi₂Sr₂CaCu₂O₈₊δ single crystals." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627030.
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Pendock, Graeme. "An investigation of minerals using microwave measurement of complex permittivity." Master's thesis, University of Cape Town, 1990. http://hdl.handle.net/11427/8339.
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Includes bibliography.Microwave measurement techniques have found many industrial and commercial applications. This measurement potential of microwaves, together with observations that different minerals show different microwave heating characteristics, suggests the possibility of applying microwave techniques to various forms of mineral analysis. Simple, low cost, on-line mineral analysis techniques are of interest to the mining industry. The objectives of this research project were to cover the background theory of microwave interaction with minerals and to investigate different microwave measurement techniques that could possibly be applied to mineral measurement. Measurements were then to be performed on selected minerals in order to observe any differences between them. Finally, to comment on the feasibility of using microwave measurement techniques for the differentiation, identification and analysis of minerals.
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Langham, Conway David. "Cryogenic sapphire dielectric resonators as microwave frequency standards : development and performance." Thesis, University of Sussex, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364164.
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Liu, Jin. "Investigation of trace amounts of gas on microvave water-cut measurement." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/3917.
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In recent years, the upstream oil and gas industry has dealt with some of the most challenging metering applications. One of these is the measurement of water percentage at the point of allocation. It is an essential requirement when test separators or the newly developed full multiphase meters are utilized for oil well production testing. Water-cut can be obtained from measurement of differential pressure, capacitance/conductance, gamma rays absorption, absorption of infrared light, coriolis mass measurement, or microwave permittivity. The use of microwave permittivity has been shown to be very effective with the added benefit of not requiring a nuclear source, as is the case with a gamma ray densitometers. A common problem encountered in oil well production testing is that of gas Âcarry-under into the liquid stream exiting the test separator. This results in a trace amount of gas entering the water-cut meter, producing errors in the water-cut reading. Gas carry-under may be caused by high liquid viscosity, improper separator operation, or poor separator design. Gas carry-under is believed to be one of the major causes of large allocation factors in oil and gas operations. Problems in clearly defining the three-phase stream as to flow regime and actual gas bubble size have been described in the technical literature. Pertinent references are discussed and compared. The issues in trying to perform such tests in the laboratory and the correlation of the data are disclosed and the difficulties in trying to correlate the effects of the entrained gas are described. Field testing and experience by at least one manufacturer of equipment has verified the effect of entrained gas, but little quantitative data relating gas-cut to increased error of measurement has been published. The objective of this work was to investigate the performance of a microwave water-cut analyzer under three-phase flow conditions to determine the impact of the presence of gas in the liquid stream. Experiments were performed that investigated the effects of entrained gas on a commercial water-cut analyzer. These tests were conducted at the Texas A&M Tommie E. Lohman Fluid Measurement Laboratory at low pressure conditions (< 40 psig). The test fluids were air, water and two types of oil: mineral oil and hydraulic oil. These experiments investigated oil continuous emulsion conditions with the Gas Volume Fraction (GVF) ranging from 0-25% and the water-cut ranging from 5-30%. Liquid flow rates were between 500-3,700 bbl/day. A 2-inch water-cut full range meter was utilized for these tests. The error in water-cut was seen to increase with increasing GVF ranging from 0% to 25%. However, the measurement remained stable over the entire range of tests. A correction was developed to correct water-cut meter readings based on the amount of gas in the liquid stream.
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Maule, Charles Stephen Marks Robert J. "Principal component and neural network calibration of a microwave frequency composition measurement sensor." Waco, Tex. : Baylor University, 2007. http://hdl.handle.net/2104/5113.
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鄧樹恩 and Shu Yan Tang. "Measurement of microwave absorption in cuprate superconductors by electron spin resonance." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1995. http://hub.hku.hk/bib/B31213662.
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Tang, Shu Yan. "Measurement of microwave absorption in cuprate superconductors by electron spin resonance /." Hong Kong : University of Hong Kong, 1995. http://sunzi.lib.hku.hk/hkuto/record.jsp?B17311998.
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Ju, Yang, and Linsheng Liu. "Nondestructive Measurement of Conductivity of Doped GaAs Using Compact Microwave Instrument." IEEE, 2008. http://hdl.handle.net/2237/12139.
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Isleifson, Dustin. "Simulation and measurement techniques for microwave remote sensing of sea ice." IEEE, 2010. http://hdl.handle.net/1993/4812.
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This dissertation presents new research into the study of simulation and measurement
techniques for microwave remote sensing of sea ice. We have embarked on a major
study of the microwave propagation and scattering properties of sea ice in an attempt
to link the physics of the sea ice medium to experimentally obtained concomitant
scatterometer measurements.
During our fieldwork, we studied the polarimetric backscattering response of sea
ice, focusing on newly-formed sea ice under a large assortment of surface coverage.
Polarimetric backscattering results and physical data for 40 stations during the fall
freeze-up of 2003, 2006, and 2007 are presented. Analysis of the co-polarization
correlation coefficient showed its sensitivity to sea ice thickness and surface coverage
and resulted in a statistically significant separation of ice thickness into two regimes:
ice less than 6 cm thick and ice greater than 8 cm thick. A case study quantified the
backscatter of snow-infiltrated frost fl
owers on new sea ice, showing that the presence
of the frost
flowers enhanced the backscatter by more than 6 dB.
In our simulation work, an efficient method for simulating scattering from objects
in multi-layered media was incorporated into a scattered-field formulation of the FVTD
method. A total-field 1D-FDTD solution to the plane-wave propagation through
multi-layered meda was used as a source. The method was validated for a TE-polarized
incident-field through comparisons with other numerical techniques involving examples
of scattering from canonically-shaped objects.
Methods for homogenization of inhomogeneous media were developed and validated
using well-known dielectric mixture models. A Monte Carlo Method for simulating
scattering from statistically rough surfaces was developed and was validated through
favorable comparison with the SPM method for rough surface scattering.
Finally, we presented a new Monte Carlo Method for simulating sea ice remote
sensing that utilized the framework of the FVTD method for scattering simulations.
The modeling process was driven by actual physical measurements of sea ice, wherein
dielectric and physics-based modeling techniques were employed. The method was
demonstrated through a series of case studies where the scattering from newly-formed
sea ice was simulated using a TE-polarized incident- eld. Good agreement between
experimental scatterometer measurements and simulated results was obtained for
co-polarized returns, whereas cross-polarized results indicated that more depolarizing
features must be taken into account.
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Ogunlade, Olumide. "Measurement of the microwave dielectric properties of liquids using waveguide structures." Thesis, University of Leeds, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.556018.
Full textAbstract:
A variety of waveguide structures have been analysed for the measurement of the complex dielectric permittivity of liquids. Mode matching techniques are im- plemented to solve the forward problem of computing the scattering parameters for a sample of known permittivity filling a rectangular metal waveguide. Three different sample geometries are used. In the first, the liquid and the sample holder completely fill the waveguide cross section. As a result, only the dominant waveguide modes are matched across the discontinuity interface and an exact an- alytical relation between the S parameters and permittivity can be written. The second and third configurations are concentric cylinders and rectangles respec- tively, partially filling a metal waveguide, hence higher order modes are taken into account in the formulation. For the partially filled rectangular sample, a generalised scattering matrix method to obtain the overall scattering parameters due to the several discontinuity regions. Iterative methods are then introduced to solve the inverse problem of recover- ing the unknown permittivity from simulated or measured scattering parameters. For the partially filled waveguides, because an exact analytical relation does not exist, objective( error) functions are defined and minimized. The partially filled rectangular sample case is extended to obtain the resonant frequency and qual- ity factor of a dielectric loaded resonant cavity, and the results compared to the approximation normally used for the cavity perturbation technique. Finally, a rectangular dielectric waveguide method for liquid measurements was developed. This method has a treatment similar to the well known free space tech- niques. It has a distinct advantage of relaxing the strict requirements of sample dimension associated with metal waveguides, especially at higher frequencies.
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Leach, Mark. "A new method for holographic measurement of microwave antenna radiation patterns." Thesis, Northumbria University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.416351.
Full textAbstract:
The rate at which new communications technologies are being developed has been immense and will continue to intensify for the foreseeable future. This evolution is fuelled by the desire to meet the wants and needs of the global community, by developing devices able to offer ever-increasing functionality, with greater complexity. To achieve this designers are forced to move to higher and higher frequencies. The antenna, as one of the fundamental building blocks of any radiated wave system, and as such, must develop along with the evolution of the communication system be it for, mobile, satellite or point to point systems. Antenna designers need to be able to test antenna, to ensure they exhibit the characteristics to which they were designed. Antenna test becomes progressively more difficult and costly as both, the operating frequency and the size of the antenna increase, especially for the measurement of the antenna Far-Field radiation pattern. Either the distance over which the measurement must be made becomes unfeasibly large or expensive measurement equipment is required to attain the phase component of the antenna field, where traditional methods for measuring close to the antenna are applied. Techniques have been developed to eliminate the need for the expensive phase measurement at reduced distances. Specifically of interest in this thesis, is the optical process of Off-Axis holography. The process allows phase information to be retained in a scalar measurement by use of a phase coherent known reference source. The reference desired reference source is a plane wave, which although possible at optical frequencies with the use of lasers is problematic at microwave frequencies. To date the plane wave characteristic required has been approximated using conventional radiating elements, which degrades the quality of the recorded holographic image. This thesis proposes a novel implementation of the Off-Axis hologram system, for application in the microwave frequency region. The novel system developed here addresses the problem of generating the desired plane wave characteristic. The conventional radiating element used to provide the near plane wave reference is replaced by a synthetic equivalent, which allows the magnitude and phase of the reference beam to be directly controlled at every measurement location required. Practical verification of the novel system proposed has been performed, with comparisons made between the results obtained from the novel technique and standard techniques used in industry. The comparisons show that the novel implementation is valid and able to provide good repeatable results.
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Pattison, L. N. "Vector non-linear measurement and characterization of high power microwave transistors." Thesis, Queen's University Belfast, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252592.
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Sekak, Fatima. "Microwave radar techniques and dedicated signal processing for Vital Signs measurement." Thesis, Université de Lille (2018-2021), 2021. https://pepite-depot.univ-lille.fr/LIBRE/EDENGSYS/2021/2021LILUN033.pdf.
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Dans le contexte de la sécurisation des systèmes de transport, la surveillance à courte distance de l’activité des personnes, en particulier du conducteur dans un véhicule, constitue un enjeu majeur dans l’amélioration du système d’aide à la conduite. L’application visée dans ce travail concerne principalement le domaine du ferroviaire.Les fréquences respiratoire et cardiaque du conducteur sont des indicateurs clés pour l’évaluation de l’état physiologique. Les méthodes de mesure conventionnelles de ces signes vitaux reposent sur des capteurs opérant en contact direct avec la peau. Par conséquent, le caractère intrusif de ces solutions ne s’avère pas adapté au domaine du transport, en particulier du fait de la gêne induite. Dans le cadre de ces travaux, une solution radar hyperfréquence opérant à faible puissance est proposée pour la mesure en continue des signaux d’activités respiratoire et cardiaque. En particulier, les signaux physiologiques (battements du cœur, mouvement mécanique de la cage thoracique) sont des indicateurs de l’activité humaine qui peuvent être détectés à distance (jusqu’à une dizaine de mètres) au moyen d’ondes électromagnétiques hyperfréquences rayonnées.Bien que la littérature montre un engouement grandissant pour le développement de techniques radars dédiés à la surveillance des personnes, il n’existe pas, à ce jour, de dispositif commercial robuste, sensible et précis. Une analyse fine des paramètres électriques et géométriques de la technique radar est proposée dans ce travail afin d’identifier les sources d’incertitudes, de définir les paramètres optimaux, de valider expérimentalement la solution proposée. Un traitement de signal original, basé sur l’approche cyclostationnaire, est mis en œuvre afin d’extraire les paramètres d’intérêt dans des environnements de mesure de référence ou perturbés. Les solutions matérielles proposées associées à un traitement de signal optimal permettent d’entrevoir des architectures de radar adaptées aux contingences hors laboratoireIn the context of securing transportation systems, short-range monitoring of people's activity, in particular the driver's activity in a vehicle, is a major issue in the improvement of the driver assistance system. The application targeted in this work concerns mainly the railway domain.Respiratory and heart rates of the driver are key indicators for the evaluation of the physiological state. Conventional methods of measuring these vital signs rely on sensors operating in direct contact with the skin. Therefore, the intrusive character of these solutions is not suited for the transportation domain, especially because of the induced discomfort. In this work, a microwave radar solution operating at low power is proposed for the continuous measurement of respiratory and cardiac activity signals. In particular, physiological signals (heartbeat, mechanical movement of the rib cage) are indicators of human activity that can be detected at a distance (up to ten meters) using radiated microwave electromagnetic waves.Although the literature shows a growing interest in the development of radar techniques dedicated to the surveillance of people, there is no robust, sensitive and accurate commercial device available to date. A detailed analysis of the electrical and geometrical parameters of the radar technique is proposed in this work in order to identify the sources of uncertainties, to define the optimal parameters, to validate experimentally the proposed solution. An original signal processing, based on the cyclostationary approach, is implemented in order to extract the parameters of interest in reference or disturbed measurement environments. The proposed hardware solutions associated with an optimal signal processing allow to foresee radar architectures adapted to non-laboratory contingencies
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Horsfield, Brendan. "The application of microwave sensing to the measurement of cheese curd moisture." University of Southern Queensland, Faculty of Sciences, 2001. http://eprints.usq.edu.au/archive/00001446/.
Full textAbstract:
There is a need in the dairy industry for instrumentation capable of providing on-line information about the moisture content of cheese during manufacture. Present measurement techniques are usually performed off-line and can be susceptible to human error. It is demonstrated that microwave-based moisture sensing techniques offer a number of potential advantages over conventional methods due to the strong interaction of microwaves with water. The permittivity of cream cheese curd and low-fat cheddar cheese curd has been measured over a range of frequencies and moisture contents in order to establish the relationship between these variables. A vector reflection coefficient measurement engine based on a six-port reflectometer has been built and tested. A suitable sensing head has been fabricated from a short length of microstrip transmission line. Two sensor characterisation models have been developed and compared with measured data. A novel algorithm has been developed to resolve the ambiguity inherent in many permittivity measurement techniques. It has been discovered that surface waves can propagate on a grounded dielectric slab covered by a material with a higher dielectric constant, provided the loss factor of the covering medium is greater than zero. It has also been found that the dominant mode of microstrip can radiate when the line is covered by a high-permittivity material, although this can be suppressed if the covering material is sufficiently lossy. There are three principal conclusions to draw from the investigation in this thesis. Firstly, changes in the moisture content of cheese curd during manufacture produce measurable variations in permittivity. Secondly, these changes can be measured accurately and cheaply using off-the-shelf microwave hardware. Finally, considerable attention must be paid to the characterisation of the sensing head if the instrument is to achieve its full potential. Promising results have been obtained in this area, however certain issues pertaining to the propagation of multiple dominant modes and higher order modes have not been fully resolved and would repay further theoretical analysis.
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Lehner, Christopher J. (Christopher Joseph) 1966. "Modeling and measurement of microwave effects in high-Tc long Josephson junctions." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/50338.
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Greenacre, Neil Robert. "Measurement of the high temperature dielectric properties of ceramics at microwave frequencies." Thesis, University of Nottingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339644.
Full textAbstract:
Measurements of the high temperature dielectric properties of ceramic materials at microwave frequencies have been made using two different experimental techniques.Data has been collected at frequencies from O.2GHz to 4.0GHz and for sample temperatures up to 1200°C. Detailed cross checking of the high temperature dielectric data obtained by the two techniques has been carried out with the help of other laboratories worldwide. An investigation of the applicability of dielectric mixture equations to practical measurement techniques is reported. The most reliabl~ estimates of permittivity were given by the Landau-Lifshitz, Looyenga equation or by a cube root extrapolation technique.Permittivity data obtained for a series of yttria stabilised zirconia samples, three differently processed silicon nitride samples and ten related glass compositions are presented. Analysis of the frequency and temperature dependence of both components of complex permittivity has been undertaken· in an attempt to identify the physical origins of the dielectric loss mechanisms. For the yttria doped zirconia samples results indicate two distinct loss mechanisms dominant over different temperature ranges. Below approximately 950K a hopping model involving short range motion of oxygen vacancies around fixed dopant ions is proposed. Above 950K thermally activated quantum mechanical tunneling of electrons is suggested as the dominant mechanism. A single loss mechanism for the entire temperature range involving the lattice loss of the silicon nitride network itself is indicated from the measurements of the hot pressed and pressureless sintered silicon nitride samples. For the reaction bonded silicon nitride samples there is evidence of a second loss mechanism due to additional ion impurities above 1410K. The measurements on the oxide glass systems add support to the belief that + 1 charged metal ions will dominate the dielectric properties of glass systems when present. The loss process has an increasing activation energy with increasing temperature which is seen to be consistent with ionic motion within the previously proposed random potential energy model. Differences in the complex permittivity with composition are attributed to variation in ionic size and metal ion-oxygen ion bond strength.
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Ogboi, Friday Lawrence. "Novel power amplifier design using non-linear microwave characterisation and measurement techniques." Thesis, Cardiff University, 2014. http://orca.cf.ac.uk/72926/.
Full textAbstract:
This thesis, addresses some aspects of the well-known, problem, experienced by designer of radio frequency power amplifiers (RFPA): the efficiency/linearity trade-off. The thesis is focused on finding and documenting solution to linearity problem than can be used to advance the performance of radio frequency (RF) and microwave systems used by the wireless communication industry. The research work, this was undertaken by performing a detailed investigation of the behaviour of transistors, under complex modulation, when subjected to time varying baseband signals at their output terminal: This is what in this thesis will be referred to as “baseband injection”. To undertake this study a new approach to the characterisation of non-linear devices (NLD) in the radio frequency (RF) region, such as transistors, designated as device-under-test (DUT), subjected to time varying baseband signals at its output terminal, was implemented. The study was focused on transistors that are used in implementing RF power amplifiers (RFPA) for base station applications. The nonlinear device under test (NL-DUT) is a generalisation to include transistors and other nonlinear devices under test. Throughout this thesis, transistors will be referred to as ‘device’ or ‘radio frequency power amplifier (RFPA) device’. During baseband injection investigations the device is perturbed by multi-tone modulated RF signals of different complexities. The wireless communication industry is very familiar with these kinds of devices and signals. Also familiar to the industry are the effects that arise when these kind of signal perturb these devices, such as inter-modulation distortion and linearity, power consumption/dissipation and efficiency, spectral re-growth and spectral efficiency, memory effects and trapping effects. While the concept of using baseband injection to linearize RFPAs is not new the mathematical framework introduced and applied in this work is novel. This novel approach NOVEL POWER AMPLIFIER DESIGN USING NON-LINEAR MICROWAVE CHARACTERISATION AND MEASUREMENT TECHNIQUES CARDIFF UNIVERISTY - UK ABSTRACT vi has provided new insight to this very complex problem and highlighted solutions to how it could be a usable technique in practical amplifiers. In this thesis a very rigorous and complex investigative mathematical and measurement analysis on RFPA response to applied complex stimulus in a special domain called the envelope domain was conducted. A novel generic formulation that can ‘engineer’ signal waveforms by using special control keys with which to provide solution to some of the problems highlighted above is presented. The formulation is based on specific background principles, identified from the result of both mathematical theoretical analysis and detailed experimental device characterisation.
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Hoang, Thuong Duc. "Optimization of future projects for the measurement of Cosmic Microwave Background polarization." Thesis, Sorbonne Paris Cité, 2018. http://www.theses.fr/2018USPCC235.
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Au cours de ma thèse, mes recherches ont porté sur le développement des projets futurs de mesure de la polarisation du fond diffus cosmologique (CMB) visant à sonder les modes B primordiaux. Pour atteindre cet objectif, il faudra non seulement une sensibilité suffisante des matrices de détecteurs, mais également un contrôle sans précédent de toutes les erreurs systématiques inhérentes aux mesures de polarisation du CMB. Une source importante d’erreur systématique est la non-uniformité ou la non-concordance des filtres passe-bande des différents détecteurs. Cet effet induit des fuites de l’intensité vers la polarisation après l’étalonnage des données. J'ai estimé le niveau de fuite pour une configuration réaliste de la prochaine mission LiteBIRD de la JAXA à l’aide de simulations et montré que l'amplitude de la fuite dépendait de la stratégie de balayage du satellite paramétrée par l'angle de rotation du satellite, l’angle de précession et les vitesses de précession et de rotation. En conclusion de cette étude, j’ai proposé des configurations quasi optimales pour LiteBIRD permettant d’atteindre l’objectif sur le rapport tenseur sur scalaire r. Le biais dû à la fuite des avant-plans dans l’intervalle 2≤l≤10 (bosse de réionisation) est de l’ordre de 5×〖10〗^(-4) et dans l’intervalle 10≤l≤200 (bosse de recombinaison) de l’ordre de 5×〖10〗^(-5). Le deuxième sujet de ma thèse était une étude instrumentale : l’interaction des particules avec une matrice de TES. Pour ce faire, j’ai utilisé le plan focal de l’expérience QUBIC (interféromètre bolométrique Q U pour la cosmologie). Le but de ce travail était de tester le comportement des détecteurs aux rayons cosmiques (tels que les constantes de temps et la diaphonie entre détecteurs). J'ai placé une source radioactive d'américium 241 devant un réseau de 256 TES à l'intérieur d'un cryostat. Lorsque les particules interagissent avec l’un des composants d’un pixel (ex: thermomètre, grille absorbante, substrat), l’énergie déposée provoque une élévation de la température d’un composant et éventuellement celui d’un pixel voisin. Cela pourrait fournir une évaluation de la diaphonie entre pixels. De plus, cette étude nous permet de comprendre les constantes de temps du système de lecture thermique et électronique d'un TESDuring my Ph.D., my research focused on the development of future projects for the measurement of Cosmic Microwave Background (CMB) polarization aimed to probe primordial B mode. Achieving this goal will not only require sufficient detector array sensitivity but also unprecedented control of all systematic errors inherent to CMB polarization measurements. One of the important effects is the bandpass mismatch error which is the effect of non-uniformity or mismatch of the bandpass filters for different detectors inducing leakage from foreground intensity to polarization after calibrating the data on CMB. I estimated the level of the leakage for a realistic configuration of the forthcoming LiteBIRD JAXA mission with simulation and found that the amplitude of leakage depends on the scanning strategy of the satellite parameterized with precession angle, spin angle, precession and rotation velocities. After the study, I proposed some nearly optimal configurations to archive the target of tensor-to-scalar ratio r. The bias from foreground leakage in the range 2≤l≤10 (reionization bump) is of the order of about 5×〖10〗^(-4) and in the range 10≤l≤200 (recombination bump) of the order of about 5×〖10〗^(-5). The second topic of my thesis was an instrumental study: the interaction of particles with a Transition Edge Sensors (TES) array using the focal plane of the ground-based QUBIC (Q U Bolometric Interferometer for Cosmology) experiment. The goal of this work was to test the behaviour of detectors to cosmic rays (such as time-constants and cross-talk). I placed an Americium 241 radioactive source in front of a 256 TESs array inside a cryostat. When particles hit one of the components of a pixel (eg: Thermometer, absorbing grid, substrate), the deposited energy induced temperature elevation among components and possibly to the neighbor pixels. This could provide an evaluation of the cross-talk between pixels. Moreover, this study allows us to understand the thermal and electronic readout system time constants of a TES
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Leitch, Erik M. Pearson Timothy J. "A measurement of anisotropy in the microwave background on 7'-22' scales /." Diss., Pasadena, Calif. : California Institute of Technology, 1998. http://resolver.caltech.edu/CaltechETD:etd-08162006-081019.
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Ning, Tong. "Evaluation of a Microwave Sensor for Powder Process Control." Thesis, University of Gävle, Department of Technology and Built Environment, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-703.
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In this thesis work, a free space microwave sensing technique to be used for power process control was investigated. Evaluation of the possibility to apply this sensing technique for determination of permittivity properties is the primary objective. Further these properties could be related to the material physical properties such as moisture content and density. Due to the fact that the permittivity properties of the material under measurement determine its measured S-parameters, such were performed throughout the whole work for the calculation of materials properties. Free space type of measurements were the primary focus of this work. Some uncertainties of free space measurement resulting from limitations in the measurement setups, instrumentation, algorithm were explored and methods to secure our measurement results to be within a specified confidence level are also discussed.
Based on the configuration of the measurement setup, two types of free space measurement were carried out. One was the reflection method where a perfect conducting metal plate is inserted between two antennas for calibration purposes and the material is placed above the plate. Only one reflection coefficient was then measured. The other was the transmission method where the measured material as placed between two antennas and all S-parameters measured. In both cases the amplitude and the phase of the S-parameters were recorded.
Three models, Debye, Cole-Cole, and Cole-Davidson have been also tested in this work to model permittivity properties of materials. Used test materials were air, plastic plate, water and icrocrystalline cellulose(MCC). Different methods using measured S-parameters for permittivity reconstruction that have been explored in previous work also were utilized in this work for same purpose. The validity of this sensing technique is determined by checking out the deviation of the recovered dielectric constant. The investigation demonstrated that the transmission method works well for reconstruction of permittivity properties as long as the material under test is low-loss. The results of the reflection method were not as satisfactory as we expected. The method was insitive to the sample thickness and shape. Also very precise measurements of the S-parameters were necessary for the correct inversion to dielectric properties, which is generally difficult due to complex measurements environment(multipath). Some of the above could be compensated with good calibration method, but it is not enough, at least with the currently existing approaches. Precise sample preparation and some improvement on the antenna should be further carried out for the reflection method to be performed better.
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Xiao, Renmeng. "Passive microwave snow mapping in Quebec." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq29810.pdf.
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Barbieri, Nicholas. "MEASUREMENT AND CHARACTERIZATION OF MICROWAVE TRANSIENT ELECTROMAGNETIC FIELDS GENERATED FROM LASER/MATTER INTERACTION." Master's thesis, University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3417.
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From past experiments conducted with high intensity lasers, it has been known for some time that laser matter interactions result in the emission of short, transient electromagnetic pulses. Previous investigations into laser generated electromagnetic pulses provide basic information regarding frequencies where such pulses may be present, along with the time duration of the pulses. Such investigations have also demonstrated a number of measurement techniques in which basic information on the pulses may be obtained. The purpose of this current investigation is to obtain a more thorough description and understands of electromagnetic pulses generated for laser matter interaction. To this end, spatial radiation patterns emanating from various laser excited matter sources was predicted using antenna theory for far field radiators. Experimentally, it is the intention of this investigation to gather comprehensive time and frequency domain data on laser matter generated electromagnetic pulses using a number of specific laser targets. Radiation detection techniques using broadband, calibrated EMC horn antennas were devised. A unique measurement system known as an inverse superhetereodyne receiver was designed, tested and demonstrated. An experimental setup using such instrumentation was established. Using the above instrumentation and experimental setup should yield comprehensive time and frequency domain data over a spectra range of 1-40 GHz and with a time resolution of 50 ps. Because the experimental system employed is calibrated, measurements can be corresponded to incident electromagnetic fields. Several tests were conducted to ensure the proper operation of experimental apparatus. A modulation test was conducted on the inverse superhetereodyne receiver to ensure that the experimentally observed signals appeared when and where predicted within the receiver's bandwidth. The experimental setup was used to measure radiation emitted from an electrostatic discharge source of known distance and discharge voltage. Frequency domain data from the discharges were collected and compiled using a Matlab application ultimately intended to measure laser matter interaction generated electromagnetic pulses, resulting in a compiled frequency domain description comprising 1-17 GHz. The inverse Fourier transform was used to retrieve the time domain response from the compiled data. The discharge gaps characteristics where systematically altered as to allow a parametric study of the compiled data. The discharge measurements demonstrate the measurement system's ability to analyze unknown, short duration; broadband microwave signals.M.S.
Department of Physics
Arts and Sciences
Physics
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Smith, Marie L. "Investigation and validation of FDTD weighting function modelling for microwave radiometric temperature measurement." Thesis, University of Glasgow, 2003. http://theses.gla.ac.uk/4846/.
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Microwave radiometry can provide a non-invasive, non-destructive and inherently safe method of temperature measurement suitable for a range of medical and industrial applications. The measured radiometric signal is formed by a convolution of the actual material temperature distribution with a coupling spatial response, or weighting function, over the viewed volume of material. The form of this weighting function depends on both the electromagnetic coupling structure (either antenna or cavity) and on the geometry and dielectric properties of the material. Through reciprocity, the weighting function can be found by computation or measurement of the power dissipation distribution (also known as the specific absorption rate (SAR)) when the coupling structure is actively excited. Knowledge of the weighting function is used to interpret the measured radiometric temperature. Chapter 1 introduces the method of microwave radiometry, its range of applications and considers the key features of weighting function determination. The suitability and validity of finite difference time domain (FDTD) SAR and weighting function modelling was investigated for the largely travelling - wave fields appropriate to surface contact antennas. An FDTD simulator, the Basic Electromagnetic Simulation Tool [3], was used to computationally model a range of antenna configurations that could then be compared directly with experimental results. Chapter 2 introduces several numerical techniques and justifies the choice of FDTD modelling. An introduction to the theory of the FDTD technique and a description of the BEST software is also given. Simulations of systems where electromagnetic field distributions are known (or can be determined experimentally) allowed the direct comparison of simulation results with theoretical predictions. Chapters 3 and 4 consider various validation examples; a monopole radiator above ground plane and TEOl waveguide in chapter 3, experimental field determination in lossy dielectrics using the non-resonant perturbation method in chapter 4. In all cases considered, simulation and experiment agree within a reasonable magnitude of error. With the successful validation of its microwave modeling capabilities, the BEST program was then used to predict the weighting functions expected for practical radiometer antennas for microwave temperature measurement. Of primary importance are the variations of the effective coupling distance into the viewed material with dielectric changes, particularly those due to water content, and with measurement frequency. Knowledge of this behaviour is essential for estimating, at one extreme, relatively small but physiologically important temperature gradients within the human body, and at the other extreme, the large and rapidly varying temperature patterns induced during industrial processes. By measuring the microwave temperature at different microwave frequencies, it is possible to retrieve information on the temperature at varying depths within the material. To aid in the interpretation of these measurements, the BEST program was used to ascertain the form of the weighting function at two frequencies, 1.35 GHz and 3.2 GHz, for a specific dual - frequency antenna in a range of phantom materials. The phantom materials were composed of a mixture of water, protein and salts, with the intention being to simulate common biological materials. To consider foodstuffs a mashed potato phantom was used. Chapter 5 includes the design of this dual frequency antenna and its application to measuring the radiometric temperature of non-isothermal mashed potato mixtures. The specific manipulation of the potato mixture (through heating and cooling) to produce known temperature profiles (quasi-linear and quasi-quadratic) is also considered in this chapter. Further validation of the BEST weighting function determination is possible by comparison with these experimental temperature measurements. Chapter 6 initially covers the modelling of the dielectric properties of the mashed potato and protein / saline mixtures. In particular, a model of the variation of the dielectric constant and loss factor of the mashed potato material, covering a wide range of temperatures at 1.35GHz and 3.2GHz, is presented and shown to agree with published literature. The effects on the computed weighting function of variation of several key factors, including measurement frequency and material temperature, are then considered for both phantom types. Further, limitations in the computational modelling in terms of finite bounds and the modelling of layers are investigated. Finally, techniques for obtaining the physical temperature distribution from multi - frequency microwave readings are considered in chapter 7 and their applicability at two frequencies is discussed. By making use of the data collected from the dual - frequency antenna and simulated microwave temperatures, the various methods of temperature profile retrieval are compared.
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Barrie, Kate. "FDTD electromagnetic modelling of cavity-based weighting functions for microwave radiometric temperature measurement." Thesis, University of Glasgow, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399668.
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Van, Rooyen M. W. (Melchior Werner). "Simple broadband measurements of balanced loads using a network analyzer." Thesis, Stellenbosch : Stellenbosch University, 2001. http://hdl.handle.net/10019.1/52451.
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Thesis (MEng)--University of Stellenbosch, 2001.ENGLISH ABSTRACT: Balanced loads such as antennas normally require baluns when they are measured. For wide band applications, designing and building a balun complicates the measurement and introduces errors. A simple model for load impedances was developed, together with a novel measurement procedure. The procedure enables the measurement of balanced loads using a network analyzer with no balun. Measured and simulated results are presented.
AFRIKAANSE OPSOMMING: Gebalanseerde laste soos antennas benodig gewoonlik balons om korrek gemeet te word. Die ontwerp van 'n balon vir wye band toepassings bemoeilik die metings en veroorsaak foute. 'n Eenvoudige model vir die lasimpedansies is ontwikkel sowel as 'n eenvoudige meetmetode. Die metode word gebruik om die gebalanseerde laste te meet met 'n netwerk analiseerder sonder die gebruik van 'n balon. Gemete en gesimuleerde resultate word getoon.
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Kemppinen, E. (Esa). "Determination of the permittivity of some dielectrics in the microwave and millimetre wave region." Doctoral thesis, University of Oulu, 1999. http://urn.fi/urn:isbn:9514251954.
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Abstract
In the first part of this study, determination of the dielectric properties of the low loss microwave ceramic material, barium nonatitanate (Ba2Ti9O20), around 1 GHz is discussed. The structures under test were coaxial resonators, the cores of which were made of barium nonatitanate and the metallization was realised by thick film silver. The measured value of the real part of the relative dielectric constant was εr = 37 and that of the loss tangent was tan σ = 0.00014. The change of the resonance frequency of the coaxial resonators with temperature, in the range -20 … +80 C, was 4 ppm/ C. In addition, realisation of compact interdigital and comb-line bandpass filters was demonstrated for the 900 MHz mobile phone band. Besides Ba2Ti9O20, Ba(Sm,Nd)2Ti5O14 ceramic material with a dielectric constant of εr = 78 was also employed in order to improve the miniaturisation. The volume of the smallest filter was 2 cm3 and the weight was 9 g.
In the second part of this study, various measurement methods have been demonstrated to determine the real part of the relative permittivity of FR4 fibreglass circuit board. Test structures were straight asymmetric open-circuited strip lines. It was found that the real part of the relative permittivity decreased slightly with frequency. At 0.72 GHz and 4.5 GHz, εr values of 4.3 and 4.1, respectively, were measured. All the characterisation methods used gave consistent values for εr, and electromagnetic simulators were used to verify the results.
In the third part of this study, the structures under test were microstrip or strip line transmission lines, the S parameters of which were measured by using on-wafer measurement techniques. It was found that the insertion loss of the 10 mm long etched Cu microstrip was slightly less than that of the Ag microstrips which were manufactured by etching and gravure offset printing techniques, respectively. The performance of the Ag microstrips was, however, similar. In addition, a theoretical basis was established for the determination of εr of the dielectric substrate and the attenuation coefficient of the transmission lines under test. The calculations were based on signal flow diagrams. The method was applied to determine the dielectric and loss properties of a commercial, Kyocera, Japan, LTCC (Low Temperature Cofired Ceramic) material up to 50 GHz. The measured value of the real part of the relative permittivity was εr = 5.7, and the loss tangent was approximately tan σ = 0.003.
The essential idea behind the studies reported in this thesis was twofold. First, the studies aimed at characterising dielectric media which find usage in the realisation of UHF, microwave or millimetre wave circuits. Second, the studies aimed to obtain data of immediate value in practical design work. For this reason, the structures under test were transmission lines having extensive usage in practical high frequency circuit design.