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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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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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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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Slot antenna
Dvořák, Petr ; Horák, Jiří (referee) ; Láčík, Jaroslav (advisor)
This thesis discusses Slot antennas that are based in gap waveguide technology, which allows them to work with high frequency signals. It contains theoretical findings about antennas and waveguides, which are later used in the design. The practical section of this thesis concentrates on designing a specific gap waveguide for 10 and 24 GHz frequencies, starting with modeling and parameter optimalization. This gap waveguide is then used as a base for slot antenna design. The final antenna is designed for frequency of 10 GHz, for both linear and right-handed circular polarizations. With right-handed circular polarization, the achieved band was approximately 1.41 GHz, while the gain was 7,6 dB.
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