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Special Methods for Microwave Vector Measurements
Urbanec, Tomáš ; Svačina, Jiří (advisor)
Theoretical principles of the sixport measurement method are presented. Description of theoretical design and influence of its parameters on measurement precision follows. Simple sixport measurement system was made and its parameters are described. As the main thesis contribution there is described a new approach to method with more detectors in the system. Mean features are more valid sixports at one specific frequency and frequency bandwidth aviable up to 1 : 100 and more. Such a wideband measurement system was designed for the frequencies between 50 and 2680 MHz and its parameters are presented in the work.
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Basic measurement on the Vector network analyzer
Lapčík, Josef ; Urbanec, Tomáš (referee) ; Dřínovský, Jiří (advisor)
This bachelor project concerns with a vector network analyzer for measurement of reflection coefficient, carry coefficient and scattering coefficients. Main parts of vector network analyzer and principle of analyzer with relation to possible areas of error correction are described. Possibilities of using modern vector network analyzer are shown in relation to their conception. Second part of the project deals with design of filters and directional coupler designed for measuring on analyzer. Designs of lowpass filter, bandpass filter and branch-line directional coupler are describe in details. Results of filters analysis from program Ansoft Designer and results of measurement on vector network analyzer are appended. The last part of project focus on creation of application for automatic measurement on network analyzer in program interface Agilent VEE.
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Miniature antenna for mobile applications
Šmarda, Marek ; Švanda,, Milan (referee) ; Pokorný, Michal (advisor)
This work deals with the most famous constructions of planar antennas. The work analyses selected methods of connecting planar antennas' charging with the possibility of impedance adaptation. An important part of the work consists of description of techniques for increasing bandwidth and conversely techniques for reducing the dimensions which are important for the design of planar antennas for mobile devices. The antennas were designed by means of theoretical basis and their properties were examined in the electromagnetic field simulator. The selected antenna model was constructed and its parameters were measured experimentally. The matching circuit for the antenna to tune it to different resonant frequencies was designed and constructed.
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Analysis of infrared acquisition parameters
Zembol, Filip ; Drastich, Aleš (referee) ; Čech, Petr (advisor)
The topic of my thesis is the analysis of parameters of the infrared imaging and the usage of these parameters for the design of a thermographic equation and a programme in the MATLAB environment in which the termography formula and the influence of the particular quantities, which take part in it, will be graphically depicted. In the thesis we will first of all introduce the infrared radiation, its types and features. With the help of the particular radiation laws and distracting elements of the infrared radiaton a formula trimming the distracting elements of the thermal relief will be designed. This formula will enable us to count the emission surface temperature of the scanned scene (grey body) and thus eliminate the elements influencing the resulting temperatures of the scanned scene. Furthermore, a programme which will image the IR acquisition model (thermogram) on the basis of the thermography equation will be designed. The thermogram will change in dependence on the changes of the thermography equation quantities. The change will be expressed by the shift of the color spectrum (thermographic scale). This programme graphically presents the changes of the quantities influencing the resulting scene and provides a better grasp of the influence and the function of particular quantities in the thermographic equation.
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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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Smith Chart Visualization Tool
Marek, Martin ; Pokorný, Michal (referee) ; Kadlec, Petr (advisor)
The objective of my bachelor thesis was to create a Smith chart visualization tool in computing environment MATLAB. I created an impedance Smith chart in graphical user interface which delineate parameters of basic line types. Parameters of transmission lines can be defined in the Smith chart as normalized impedance, reflection coefficient, normalized admittance or impedance in combination with line’s characteristic impedance. It is also possible to design simple matching circuits, e.g. with quarter-wave transformer, series stub, parallel stub or matching circuits with lumped elements.
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Analysis of infrared acquisition parameters
Zembol, Filip ; Drastich, Aleš (referee) ; Čech, Petr (advisor)
The topic of my thesis is the analysis of parameters of the infrared imaging and the use of radiation laws for the formation of a thermographic equation, which will include the impact of surrounding factors on the resulting temperature relief of the scanned object. These factors include the temperature of the surrounding atmosphere, temperature of the surrounding radiation sources, emissivity coefficients, reflection and transmission. On the basis of this equation a programme will be created in the MATLAB environment where the resulting temperature relief of the simulated object and the impact of the particular parameters from the equation will be graphically depicted. In the thesis we will first of all introduce the infrared radiation, its types and features. With the help of the particular radiation laws and distracting elements of the infrared radiation a formula including the distracting elements appearing during scanning of the thermal surface relief will be formed. This formula will enable us to count the surface temperature of the scanned scene and to determine the final temperature without the impact of the unwanted parameters. Furthermore, a programme which will image thermograms on the basis of the thermography equation will be designed. The thermogram will change in dependance on the changes of the parameters in the thermography equation. The change will be expressed by the change of temperatures in the scanned scene and by the shift in the colour spectrum (thermographic scale). This programme will graphically present the changes of the quantities influencing the resulting temperature division in the scene and will provide a better grasp of the influence and the function of particular quantities in the thermographic equation.
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Quarter-mode four-element antenna array
Janoušek, Jiří ; Fiala, Pavel (referee) ; Raida, Zbyněk (advisor)
Thesis deals with problematics of Compact Circularly Polarized Antenna Based on Quarter-Mode Substrate Integrated Waveguide Sub-Array and process. It also solves a complex structure of microstrip power distribution network. The goal was to create a~physical functioning model of this antenna and to measure its attributes in free space and also near the human body. Theoretical part of this work is taking on the calculation of parameters of the proposed antenna. Practical part is then solving modelation and simulations in program ANSYS HFSS. Physical model of the antenna was not created and some flaws were found in the presented model of the microstrip power distribution network. A possible solutions were proposed to eliminate these flaws.
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Impedance matching of a transmission line in Matlab
Straka, Zdeněk ; Láčík, Jaroslav (referee) ; Štumpf, Martin (advisor)
This bachelor’s thesis is aimed at the impedance matching of transmission lines and at understanding of the Smith chart plotting. In the text are described the basic features of the transmission line theory, i.e. the behavior of voltage and current along the lines in different situations. The construction of the Smith chart is described in detail. The Smith chart serves for the transformation of impedance and reflection coefficient along the transmission line. In conclusion, advantages and disadvantages of the matched transmission line are discussed. The project presents a demonstration program using examples. The program is used for illustrative example of the matched impedance and the behavior of voltage and current along the lines in different situations
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Circularly polarized superstrate antenna for CubeSat
Kratochvíl, Dušan ; Olivová, Jana (referee) ; Raida, Zbyněk (advisor)
The thesis is focused on parameter verification of a circularly polarized antenna with a superstrate, which was designed for CubeSat and presented in the research paper [1]. The frequency band of the designed antenna is from 8.35 to 8.95 GHz. First, the antenna is analyzed without the superstrate layer. Varying the feed position and antenna element dimensions, the changes of reflection coefficient at the input is matched. Second, an overall simulation with a superstrate layer is performed. The antenna substrate was replaced with ARLON 25N microwave substrate available in the laboratory, and the antenna was optimized for this substrate. Finally, such an antenna is fabricated, and its measured parameters are compared with the simulation results.
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