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Textile slot antenna
Špůrek, Jan ; Polívka,, Milan (referee) ; Raida, Zbyněk (advisor)
This diploma thesis is focused on design of various antenna structures, based on slot antennas, created in the wider wall of a rectangular-shaped waveguide. As the substrate, it is used a 3D textile material, while its properties are examined. They were designed structures, that operate with linear and circular polarization, and other related structures, that are used for feeding and power division. Structures are designed to operate at central frequency of 8 GHz and its vicinity.
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New trends in fibre optic sommunications
Lubajo, Lubajo Moses Wolyan ; Dejdar, Petr (referee) ; Münster, Petr (advisor)
Přenos optickych vláken je jednou z hlavních metod přenosu informací pro přenos na velké vzdálenosti. Byly vyvinuty různé modulační formáty pro maximalizaci informací přenášenych prostřednictvím komunikačního kanálu. Takové formáty sahají od formátů, které přenášejí jeden bit na symbol (jako je například binární fázové posunování klíčů, BPSK), a nebo vice, jako je například Kvadraturní fázové posunovací klíčování, duální polarizační kvadraturní fázové řazení a mnoho dalších ostatní modulace. Cílem diplomové práce je vytvořit a implementovat přenosovy systém s rychlostí 100 Gbps pomocí modulace formátu DP QPSK. Vysledky jsou shrnuty s ohledem na to, co bylo úspěšně implementováno, a zlepšení, která mohou byt ještě učiněna pro zvyšení přenosové vzdálenosti a snížení BER mimo jiné. Použitysimulační software je PHOTOSS.
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3D printed microstrip patch antenna
Medek, Petr ; Vašina, Petr (referee) ; Láčík, Jaroslav (advisor)
The bachelor thesis deals with the issue of inhomogeneous substrates of microwave patch antennas. The aim of this work was to find such a distribution of the permittivity of the substrate of a linearly polarized patch antenna, which would be possible to achieve an extension of the impedance bandwidth to an antenna with the same effective permittivity. The investigated patch antenna has a square shape, is linearly polarized, and is powered by a coaxial power supply. Few types of permittivity distribution are presented and compared with an antenna with a substrate with an adequate effective permittivity. For each antenna, the dimensions of the patch are adjusted so that the antenna is designed at a medium frequency of 2.45 GHz. Furthermore, an antenna with a constant permitivity with patch dimensions is designed and the permittivity of the substrate is adjusted so that the required frequency is achieved. In the two investigated styles, we observe an extension of the impedance bandwidth to the antenna with adequate effective permittivity in the order of hundreths of percent, which was subsequently verified by manufacturing and measuring.
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Patch antenna with switchable polarization
Havelka, Michal ; Pokorný, Michal (referee) ; Raida, Zbyněk (advisor)
The bachelor’s thesis deals with the analysis of basic planar antennas, the design methods, optimization and simulation in ANSOFT Designer. Attention is turned to the design of aperture coupled microstrip antennas. First, the antenna with a simple slot is designed. Second, the design of the ring slot coupled microstrip antenna is described. Both the antennas are designed for the operation frequency 2,45 GHz. The second part is devoted to the antenna with switchable polarization. Using three PIN diodes powered by lithium battery of 3-V, the linear polarization (both the horizontal one and the vertical one) and the circular polarization (both the right-hand one and the left-hand one) can be switched. The results were verified by experimental verification.
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Preparation and Characterization of Fluoride Conversion Coatings on Biodegradable Magnesium Alloys
Drábiková, Juliána ; Hadzima, Branislav (referee) ; Brezinová,, Janette (referee) ; Ptáček, Petr (advisor)
The submitted work is aimed at the unconventional fluoride conversation coating preparation on the AZ31, AZ61, ZE10 and ZE41 magnesium alloys by their immersion in Na[BF4] molten salt. The influence of the preparation parameters (such as temperature and time) on the quality of the fluoride conversion coating is investigated. Methods of light and scanning electron microscopy were used for the evaluation of morphology, chemical composition and thickness of the coating. Short and long-term corrosion tests were executed to analyze the corrosion performance in simulated body fluid solution at 37 ± 2 °C with and without the fluoride conversion coating. The short-term behavior was evaluated by potentiodynamic tests, namely by the linear polarization. Long-term performance was assessed by electrochemical impedance spectroscopy or immersion tests. The coating preparation parameters influence on the character of the formed fluoride conversion coating was defined based on the obtained results. The next part of the thesis deals with the description of the possible mechanism of formation and kinetics of growth of the unconventional fluoride conversion coating on the selected AZ61 magnesium alloy. In this part, further detailed analyses were carried out to investigate the microstructure and chemical composition of the fluoride conversion coating using focused ion beam, transmission electron microscopy and X-ray photoelectron spectroscopy.
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Evaluation of corrosion properties of biodegradable ZE41 magnesium alloy
Honč, Jiří ; Minda, Jozef (referee) ; Tkacz, Jakub (advisor)
This thesis deals with evaluation of corrosion properties of biodegradable magnesium alloy ZE41. Corrosion characteristics of ZE41 wrought magnesium alloy specimens with polished and grinded surface were examined by electrochemical methods. 0,1M NaCl solution was used as corrosive environment. Short-term tests were performed using linear polarization method, by which the corrosion potential, corrosion current density and corrosion rate was determined. Long-term evolution of corrosion behavior in terms of polarization resistance was studied by electrochemical impedance spectroscopy (EIS) during 168 hours. Also, the corrosion products were characterized by scanning electron microscope (SEM) with energy-dispersive spectroscopy (EDS). Based on the results, the influence of phase composition and surface treatment on corrosion characteristics was discussed.
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Evaluation of corrosion properties of biodegradable ZE41 magnesium alloy in simulated body fluid
Handlíř, Tadeáš ; Minda, Jozef (referee) ; Tkacz, Jakub (advisor)
The bachelor thesis is focused on the evaluation of the effect of processing of biodegradable magnesium alloy ZE41 on its corrosion properties. The corrosion properties of ZE41 wrought magnesium alloy specimens with polished and ground surface were evaluated based on the results of the electrochemical characteristics that took place in the simulated body fluid. Short-term tests were performed using linear polarization method, by which the corrosion potential, corrosion current density and corrosion rate was determined. Long-term evolution of corrosion behavior in terms of polarization resistance was studied by electrochemical impedance spectroscopy (EIS) during 168 hours. Also, the corrosion products were studied by scanning electron microscope (SEM). Based on the results, the influence of surface treatment and phase composition on corrosion characteristics was evaluated.
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Electrochemical characteristics of AZ31 and AZ61 magnesium alloys in Hanks‘ solutions
Minda, Jozef ; Wasserbauer, Jaromír (referee) ; Tkacz, Jakub (advisor)
This thesis deals with the characterization of electrochemical corrosion properties of magnesium alloys as promising materials for biomedical applications. The wrought alloys AZ31 and AZ61 were used and exposed to corrosive environments of Hanks solutions (SBF) to simulate environmental conditions in living organisms. For the evaluation of the surfaces was used scanning electron microscopy (SEM) with elemental analysis measured by energy-dispersive spectroscopy (EDS). Short-term (5 min) and long-term (72 h) corrosion tests were conducted in order to optimize the measurement methodology and obtain corrosion parameters - especially corrosion potential (Ekor), corrosion current density (ikor) and polarisation resistance (RP). To evaluation of the short-term tests were by potentiodynamic tests, namely the linear polarization (LP) test. Long-term tests were measured by electrochemical impedance spectroscopy (EIS). Effects of the composition of the alloys (AZ31 and AZ61), surface treatment (grinding and polishing) and the composition of the solution (SBF without Ca, Mg, and with Ca, Mg) were compared. Complex corrosion behaviour in time was characterized and corrosion mechanisms were discussed.
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3D printed microstrip patch antenna
Medek, Petr ; Vašina, Petr (referee) ; Láčík, Jaroslav (advisor)
The bachelor thesis deals with the issue of inhomogeneous substrates of microwave patch antennas. The aim of this work was to find such a distribution of the permittivity of the substrate of a linearly polarized patch antenna, which would be possible to achieve an extension of the impedance bandwidth to an antenna with the same effective permittivity. The investigated patch antenna has a square shape, is linearly polarized, and is powered by a coaxial power supply. Few types of permittivity distribution are presented and compared with an antenna with a substrate with an adequate effective permittivity. For each antenna, the dimensions of the patch are adjusted so that the antenna is designed at a medium frequency of 2.45 GHz. Furthermore, an antenna with a constant permitivity with patch dimensions is designed and the permittivity of the substrate is adjusted so that the required frequency is achieved. In the two investigated styles, we observe an extension of the impedance bandwidth to the antenna with adequate effective permittivity in the order of hundreths of percent, which was subsequently verified by manufacturing and measuring.
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New trends in fibre optic sommunications
Lubajo, Lubajo Moses Wolyan ; Dejdar, Petr (referee) ; Münster, Petr (advisor)
Přenos optickych vláken je jednou z hlavních metod přenosu informací pro přenos na velké vzdálenosti. Byly vyvinuty různé modulační formáty pro maximalizaci informací přenášenych prostřednictvím komunikačního kanálu. Takové formáty sahají od formátů, které přenášejí jeden bit na symbol (jako je například binární fázové posunování klíčů, BPSK), a nebo vice, jako je například Kvadraturní fázové posunovací klíčování, duální polarizační kvadraturní fázové řazení a mnoho dalších ostatní modulace. Cílem diplomové práce je vytvořit a implementovat přenosovy systém s rychlostí 100 Gbps pomocí modulace formátu DP QPSK. Vysledky jsou shrnuty s ohledem na to, co bylo úspěšně implementováno, a zlepšení, která mohou byt ještě učiněna pro zvyšení přenosové vzdálenosti a snížení BER mimo jiné. Použitysimulační software je PHOTOSS.
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