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Web application for antenna analysis
Večeřa, Štěpán ; Kadlec, Petr (referee) ; Raida, Zbyněk (advisor)
Měla být vyvinuta webová aplikace pro zjednodušenou analýzu anténních polí. sestávající z drátových dipólů nebo náplasťových prvků. Původně se předpokládalo, že výpočetní jádro bude vyvinuto v prostředí MATLAB a webové rozhraní v jazyce Python. Studie proveditelnosti ukázala, že plné v jazyce Python je výhodné. Vyvinuté funkce Pythonu pro analýzu a syntézu antén jsou stručně popsány a jejich funkčnost je ověřena v prostředí MATLAB.
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Circularly polarized antenna integrated into 3D knitted fabric
Drápal, Ladislav ; Kadlec, Petr (referee) ; Raida, Zbyněk (advisor)
The thesis deals with the circularly polarized planar antenna with a working frequency of 5.8 GHz, which was published in [1]. For the antenna, a numerical model in ANSYS HFSS was created to verify the correctness of published parameters. The antenna [1] is of a relatively complicated geometry. In order to demonstrate sense of this geometry, a numerical model of a circularly polarized patch antenna with a working frequency of 5.8 GHz [2] was created. Simulated parameters of both the circularly polarized antennas were mutually compared. The antenna [1] was shown to exhibit a better directivity and a higher gain in the main lobe direction. Both the antennas were then optimized for the 2.4 GHz operation band and a textile substrate. Simulations showed that the patch antenna exhibits on a lower frequency and a textile substrate a higher gain and a better directivity. Both the antennas were manufactured by using a copper foil. The circularly polarized planar antenna [1] was additionally manufactured by screen printing to achieve better parameters. Measurement showed that the best parameters reach the patch antenna [2]. Planar antennas [1] in the 2.4 GHz frequency band did not meet the expectations by the size and complexity on the textile substrate.
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Artificial magnetic conductor for textile-integrated circularly polarized antenna
Ritter, John Richard ; Kadlec, Petr (referee) ; Raida, Zbyněk (advisor)
This thesis deals with a circularly polarized antenna using an artificial magnetic conductor (AMC). The concept for this antenna is adopted from [1]. The antenna structure was simulated in its original, published form to verify the validity of the results in [1]. The antenna structure was then modified for manufacturing on a textile substrate and for operation in the ISM 5,8 GHz frequency band. After the modification the antenna was manufactured. The antenna properties were subsequently measured to verify the simulated results. The antenna can be potentially used in wireless communication systems, such as wireless body area networks (WBAN).
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Pixelated electrically small antenna
Turák, Samuel ; Kadlec, Petr (referee) ; Zechmeister, Jaroslav (advisor)
This bachelor thesis deals with the problematic of programming and implementation of binary evolutionary algorithms and their practical application for design of pixelated electrically small antenna for ISM band 868 MHz. Two binary evolutionary algorithms are introduced and implemented, both created in the programming environment Matlab. The basic antenna design and its optimization are performed by the program CST controlled by an in-house Matlab code. In the thesis, an empiric research of miniaturization and sensitivity of the electrically small antenna is conducted.This bachelor thesis deals with the problematic of programming and implementation of binary evolutionary algorithms and their practical application for design of pixelated electrically small antenna for ISM band 868 MHz. Two binary evolutionary algorithms are introduced and implemented, both created in the programming environment Matlab. The basic antenna design and its optimization are performed by the program CST controlled by an in-house Matlab code. In the thesis, an empiric research of miniaturization and sensitivity of the electrically small antenna is conducted.
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Multi-Context Reputation System for WWW
Kadlec, Petr ; Zbořil, František (referee) ; Samek, Jan (advisor)
This Diploma Thesis introduces the basic concepts of reputation and trust, reputation systems and problems of multi-contextual models of reputation. It also describes practical aspects of multi-contextual models in web environment. Described contextual models are then used for design and implementation of real web application.
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Multiobjective optimization of electromagnetic structures based on self-organizing migration
Kadlec, Petr ; Prof. Hans L. Hartnagel (referee) ; Škvor,, Zbyněk (referee) ; Raida, Zbyněk (advisor)
Práce se zabývá popisem nového stochastického vícekriteriálního optimalizačního algoritmu MOSOMA (Multiobjective Self-Organizing Migrating Algorithm). Je zde ukázáno, že algoritmus je schopen řešit nejrůznější typy optimalizačních úloh (s jakýmkoli počtem kritérií, s i bez omezujících podmínek, se spojitým i diskrétním stavovým prostorem). Výsledky algoritmu jsou srovnány s dalšími běžně používanými metodami pro vícekriteriální optimalizaci na velké sadě testovacích úloh. Uvedli jsme novou techniku pro výpočet metriky rozprostření (spread) založené na hledání minimální kostry grafu (Minimum Spanning Tree) pro problémy mající více než dvě kritéria. Doporučené hodnoty pro parametry řídící běh algoritmu byly určeny na základě výsledků jejich citlivostní analýzy. Algoritmus MOSOMA je dále úspěšně použit pro řešení různých návrhových úloh z oblasti elektromagnetismu (návrh Yagi-Uda antény a dielektrických filtrů, adaptivní řízení vyzařovaného svazku v časové oblasti…).
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Mesh Generator for the Finite Element Method
Ščišľak, Tomáš ; Čapek, Miloslav (referee) ; Kadlec, Petr (advisor)
The paper describes basic principles of the finite element method. Further, basic properties of triangulation are discussed. The thesis is primarily focused on the Delaunay and Greedy triangulation. Greedy triangulation is simple to implement, but may not produce the optimal shape of triangles. Delaunay method is used due to its robustness in a wide range of fields especially in computer graphics. This method is relatively easy to implement and provides triangles with high quality.
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Channel estimation in CDMA systems
Kadlec, Petr ; Prokopec, Jan (referee) ; Kejík, Petr (advisor)
The subject of this work deals with the problem of channel estimation for CDMA systems. This method of multiple access when individual users share the same full bandwidth simultaneously and are differentiated with any of pseudorandom sequences, is now the most perspective method. That is proved by its wide implementation in mobile networks of the third generation and higher systems. This work describes basic theory principles of spread spectrum, above all DS-CDMA (Direct Sequence-CDMA) and furthermore some phenomena of radio wireless channel that affect changes in transmitted signal in its way from transmitter to receiver. Terms of fading, multipath propagation, loss, refraction, scattering of the wave and Rice and Rayleigh probability density functions are mentioned. The third chapter deals with yet known and used capabilities of channel estimation. Differences, advantages and disadvantages of so-called blind estimation or training-based estimation are discussed. Two algorithms: LS method and sliding correlator are analyzed in more detail. There is also description of their simulations in Matlab and some results of these simulations are discussed. The last chapter deals with comparison of main characteristics and achievable accuracy of wireless channel impulse response estimation by both methods, and their possible utilization in real live.
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Computer modeling of implantable antennas
Deneš, Roman ; Kadlec, Petr (referee) ; Raida, Zbyněk (advisor)
The thesis deals with a design of planar antennas and their simulation in the vicinity of a human body. The main goal of this thesis is parametrically analyse different types of planar antennas and find out which one possesses the highest quality in the vicinity of a human body. The design and simulation were made in a software called CST Microwave Studio. Firstly, the attention is paid to the concept of designing and simulation. Further, they are made and tested.
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