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Numerical Modeling of Periodical Structures
Nešpor, Dušan ; Bartušek, Karel (referee) ; Brančík, Lubomír (referee) ; Fiala, Pavel (advisor)
The thesis discusses the dynamic electromagnetic field on periodic structures. The author focuses on three principal types of resonant structures, considering their application possibilities. In general, these types can be individually defined as follows: materials exhibiting a negative refractive index of the incident electromagnetic wave; structures with gradual changes in impedance, characterised by their usability as reflectionless surfaces; and periodic structures able to conveniently shape the magnetic field distribution. Materials of the third group within the above-shown short list facilitate the fabrication of magnetoinductive lenses for nuclear magnetic resonance. The presented analysis of the properties of periodic resonant structures is mainly based on numerical models utilising the finite element method, and this approach is combined with both the derivation of the corresponding analytical relations and an experimental measurement of the non-radiating component of the electromagnetic field. The thesis includes a physical description of the basic elements of periodic resonant structures. Physical properties of the elements were examined in detail via numerical analysis. In the course of the research, the data acquired through this analysis and the related experimental measurement enabled the author to propose a method for optimising the most widely used resonant structures. Moreover, several new versions of resonant elements, structures, and fabrication techniques were also designed. The results obtained from the numerical analyses carried out to examine the central physical properties of the fabricated structure samples were all verified via the designed method for measuring the non-radiating component of the magnetic field.
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Exploatation of VHF, UHF, SHF, and EHF frequency bands in civil & military aeronautic radars (handbook)
Jasimová, Rafah ; Šplíchal, Miroslav (referee) ; Vosecký, Slavomír (advisor)
VHF, UHF, SHF, EHF, radar, wave propagation, electromagnetic wave, active radiolocators, passive radar system
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RF power meter
Hlaváč, Štěpán ; Jedlička,, Petr (referee) ; Drexler, Petr (advisor)
This master’s thesis describes various principles of measurement of electromagnetic waves in a free space and on a line. Used sensors and their real parameters are given for every method. The analysis of protections of high-frequency inputs of measuring instruments is done here and the most suitable method and protections of input for realization are chosen. The analysis of design of secondary protection of high-frequency input is done in this project. The protection of input is realized and measured. The suitable method of measurement is chosen as well as the sensor for measurement of power. The block diagram and circuit diagram of the meter of power are designed. According to designed conception the measuring instrument for measurement of power is realized and its single qualities are measured during the realization. In the final part its precision is measured and the evaluation of results is done.
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Wireless local area network design
Šenkyřík, Marek ; Kubánková, Anna (referee) ; Koton, Jaroslav (advisor)
This work explores the topic of wireless local networks and their implementation. The introduction of the theoretical part is dedicated to physical principle of electromagnetic wave, air wave transfer, legislation of wireless networks and transmit power limitations and regulations. The thesis also presents WLAN networks functionality and their application. The practical part of the thesis contains the WLAN network for covering buildings and their surroundings. The second network scenario is about remote connections, both backbone and endpoints.
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Analysis of an Electromagnetic Wave on the Boundary between Electromagnetic Materials
Kadlec, Radim ; Lazar, Josef (referee) ; Macháč, Jan (referee) ; Kroutilová, Eva (advisor)
The proposed dissertation thesis contains an analysis of conditions on the boundary between layers having varied electromagnetic properties. The research is performed using consistent theoretical derivation of analytical formulas, and the underlying problem is considered also in view of multiple boundaries including the effect of the propagation of electromagnetic waves having different instantaneous speed. The author presents a survey and formulation of the basic characteristics of methods used for electromagnetic wave propagation analysis; in this respect, special emphasis is placed on radial models. The processing of the topic involved the designing and verification (using a set of different, layered planar materials) of algorithms to analyze the electromagnetic field components. The algorithm was assembled to enable simple evaluation of all components of the electromagnetic field in relation to the speed of the wave propagation in a heterogeneous environment. The proposed algorithms are compared by means of different numerical methods for the modelling of electromagnetic waves on the boundary between materials; moreover, electromagnetic field components in common points of the model were also subject to comparison. When in conjunction with tools facilitating the analysis of material response to the source of a continuous signal, the algorithms constitute a supplementary instrument for the design of a layered material. Such design enables the realization of, for example, recoilless plane, recoilless transition between different types of environment, and filters for both optical and radio frequencies.
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The influence of air ionization on the laser beam propagation
Fučík, Milan ; Kubásek, Radek (referee) ; Drexler, Petr (advisor)
The semester project deals with the mechanisms of propagation of electromagnetic wave in ionized environment. The focus is placed on the propagation of light in ionized air. The air ionization influences its properties in the view of its material parameter – permittivity. The change of air permittivity results in the light speed reduction. The theoretical analysis of light propagation is carried out in the work in the view of impact on the light speed. The light speed reduction in ionized air is experimentally verified. The conclusions on the practical utilization of this ionization measurement method are given.
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Fiber optic source of laser radiation
Fučík, Milan ; Hudcová, Lucie (referee) ; Drexler, Petr (advisor)
This master’s thesis deals with parameters and properties of electromagnetic wave, its spread in environment and then in optical fiber, as well with optical fibers. Principle of laser sources and a issues of coupling a optical performance into optical fiber are described here. Next a function of laser diodes, power and cooling requirements are described. A block diagram of fiber optic source of laser radiation is designed as well as a circuit solution of every single block with respecting of parameters and sensitivity of used laser diode. The protection of laser diode and high-frequency modulation of optical power are solved. Subsequently the construction of every single block was done and the right function of constructional solution was tested.
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Wave propagation in homogeneous line
Brázda, Daniel ; Steinbauer, Miloslav (referee) ; Friedl, Martin (advisor)
This work deals with the propagation of electromagnetic waves. In the theoretical section describes the propagation of waves in the open space and the line. The main objective of this work is to design a new layout laboratory exercises in which students measure the behavior of waves on a homogeneous line. The design include measuring the standing wave ratio (SWR) using the digital SWR meter, measure the voltage measured along the line and measuring the frequency dependence of the input impedance of the line.
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Cellular Network Coverage Model
Unzeitig, Lubomír ; Mikulka, Jan (referee) ; Gleissner, Filip (advisor)
This work deals with a mobile signal propagation in electromagnetic wave form in a real environment of city microcell. The electromagnetic wave passing through the city environment is affected by many kinds of mechanism. It includes especially diffraction along vertical edges of buildings, diffraction across building roofs and buildings or ground refraction. These mechanisms are time variable. If we want to predicate them, we have to use sort of approached model. For an experimental part of this work, the Berg’s recursive model with a possibility of path loses or signal level prediction in a selected microcellular system is chosen. The software for a cellular network coverage is created on the basis of this fact. Its advantage is a possibility of up to five base stations placing and many kinds of settings, e.g. operating frequency, base station transmitting power, base and mobile station antennas height etc. There is a possibility of system GSM 900, GSM 1800 or UMTS choice. The Berg’s recursive model features are checked by simulations on experimental and real maps of build-up area.
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Superconductivity in the fourth state of matter
Mádrová, Tereza ; Klíma, Miloš (referee) ; Fiala, Pavel (advisor)
This master thesis is focused on description and research of electromagnetic waves in plasma state. Some simple cases of no-loss mode distribution of electromagnetic waves in plasma are known, for example around the coaxial cable. In other words, the properties of superconducting state in materials are shown. This view of plasma properties can significantly help to clarify observed phenomena in experimental plasma research or to outline new trends in plasma usage in this mode. The introduction and the theoretical parts describe the known theory related to the propagation of electromagnetic waves in a non-homogeneous or anisotropic environment, in the next parts of the thesis the mathematical model of the solved problem of wave propagation in plasma is mentioned and the design and realization of the experiment is followed. The model includes processing of Maxwell's reduced equations in Haeviside notation for the state of matter referred to as plasma, the design of a model for numerical modeling and analysis, and the design of a simple experiment to verify numerically analyzed results.
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