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Terahertz Antenna Arrays for Communications
Warmowska, Dominika ; Joler, Miroslav (referee) ; Pokorný, Michal (referee) ; Raida, Zbyněk (advisor)
The thesis is focused on the research of THz antenna arrays to be used for communications. Attention is turned to modeling metallic surfaces at THz frequencies, a proper characterization of gold conductivity, its relation to Drude model and corresponding measurements. Moreover, the best methods for modeling thin metallic layers (depending on the skin depth related to the metal thickness) are presented. An optimized element of a THz 2×2 antenna array designed for the application of communications is developed in a way that enables an expansion to a larger array. The expansion ability is demonstrated on a 4×4 antenna array which is presented in the thesis too. The designed antennas achieve parameters better than the state-of-art antennas. The presented antennas radiate circularly polarized wave at THz frequencies, operate in a wide bandwidth, have a high gain and are of a compact size. In the thesis, an 8×8 antenna array with a beam steering capability is presented. The main beam of the antenna array can be controlled in two dimensions. A high gain of the radiated circularly-polarized wave can be achieved that way. Different approaches to modeling antennas with thin metallic layers are compared and the best methods are recommended from the viewpoint of different requirements. The designed 2×2 and 4×4 antenna arrays are manufactured using a microfabrication technology. Each step of the fabrication is described in detail and discussed. The reflection coefficient at the input of antennas is measured and compared with simulations. Discrepancies in results are associated with surface roughness which is analyzed by a scanning probe microscope and a scanning electron microscope. By down-scaling the developed THz antenna, a low-profile high-gain antenna for Ka-band space applications is designed. The presented antenna achieves better results than state-of-art CubeSat antennas. The antenna performance is verified by a prototype to be operated at 9 GHz, and the radiation characteristics are experimentally confirmed.
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Thermal analysis of Gunn diode
Chára, Pavel ; Lukeš, Zbyněk (referee) ; Pokorný, Michal (advisor)
The aim of bachelor’s project has been thermal analysis of Gunn diode. Gunn diode model involving thermal effects was analyzed in COMSOL Multiphysics. Another task was to design a suitable heat sink for diode and its proper function to verify simulations.
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Computer modeling of FET transistors
Kaupa, Petr ; Pokorný, Michal (referee) ; Raida, Zbyněk (advisor)
The project deals with FET transistors, basic principles of their operation and their properties. The project is dominantly focused on modeling FET transistors in FEMLAB. The project describes the optimization of the model of the simulated transistor. The optimization is aimed to reach the match between the model of the transistor and parameters of real transistors. The optimization algorithm is programmed in MATLAB. This algorithm is based on the particle swarm method.
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Planar transmission line on semiconductro substrate
Chára, Pavel ; Harwot, Ondřej (referee) ; Pokorný, Michal (advisor)
The aim of this thesis is to acquaint with the various types of the planar transmission lines and discuss their properties. Subsequently, the development of the real models of selected lines and verification their properties by simulations using COMSOL Multiphysics. The second part deals with the modeling of the semiconductor substrate, which replacing the dielectric substrate used for the transmission lines in the first part. The final part deals with the verification of calculation results in a specialized program TiberCAD.
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Manufacturing of a post anchor base by compound tool
Pokorný, Michal ; Štroner, Marek (referee) ; Peterková, Eva (advisor)
The bachelor thesis deals with the design of a production process of an anchor, which is used to connect wooden beams to a concrete base. Steel sheet 11 375 of a 4 mm thickness was chosen for the production. A combination of cutting and bending technologies will be used to achieve the desired shape of the component. Technological and control calculations were performed for the cutting and bending operations. Based on the calculations, the compound tool was designed and constructed and a drawing documentation of it was created. A semi-finished product in the form of a roll sheet will be used for production. The PMV 300 mechanical press, supplemented by a feeding line, was proposed as a suitable machine for production.
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Mutual coupling reduction techniques in microstrip patch phased arrays
Horník, Milan ; Pokorný, Michal (referee) ; Mikulášek, Tomáš (advisor)
This thesis deals with the investigation of the mechanisms of the formation of mutual coupling and its suppression between a pair of patches located above the common ground plane. The thesis includes an analysis of mutual coupling formation and a proposal of techniques dealing with its suppression. To analyse the mutual coupling, a pair of patch elements in both polarizations was designed and their mutual coupling was investigated. A suitable variation of the techniques was selected based on a study of the available suppression techniques of mutual coupling. The antenna designed by the selected technique was simulated and later produced. With interest, the suppression technique was used, extended to an 8x1 element array, and the function of a phased antenna array was tested.
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ICT support of education in Youth diagnostic centers
Pokorný, Michal ; Brdička, Bořivoj (advisor) ; Leipert, Jiří (referee)
The thesis is focused on an investigation of the benefit evoked by the ICT supported connected instruction between the Child Diagnostic Institute (the DDU) and the tribal school of a pupil, who comes to DDU for a voluntary diagnostic stay (DDP). The aim of this work is to determine an interest in this project among teachers, both from DDU and teachers from primary schools, whose pupils attended the DDU. The method of research is an online survey among teachers from DDU and teachers from schools outside the Diagnostic Institute who have experience with the DDU clients. The results are evaluated separately for teachers from DDU and teachers from other primary schools that have experiences with those pupils.
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