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Modeling of planar antenna loaded with ring resonators
Šrajbr, Michal ; Kovács, Peter (referee) ; Láčík, Jaroslav (advisor)
This bachelor’s thesis is focused on the design of the dual-band printed dipol loaded with split ring resonators. The principal of this antenna is described in the first part. The main focus is on the design and tuning of the split ring resonators on the required working frequency in the CST Microwave Studio program. These results are used for designing dual-band printed dipol loaded with split ring resonators working at resonance frequencies of 1,8 a 2,4 GHz. The simulation of this antenna was performed in the IE3D program Zeland. The designed dual-frequency printed dipole has been manufactured and measured.
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Woven antennas
Fikar, Jan ; Pítra, Kamil (referee) ; Raida, Zbyněk (advisor)
The thesis is aimed to design textile antennas that can operate in the ISM band 5.8 GHz. Attention is turned to practical exploitation of these antennas under regular conditions. Variations of the bandwidth of the antenna due to washing and waterproofing will be observed. Finally, the impact of the proximity of living tissue on the parameters of antennas will be studied.
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Ant colony optimization of antennas on EBG substrates
Wilder, Roman ; Lukeš, Zbyněk (referee) ; Horák, Jiří (advisor)
This diploma thesis deals with optimization of planar antennas on the Electromagnetic Bandgap (EBG) substrates by the help of Ant Colony Optimization (ACO). This method is based on the communications mechanisms of a real ant colony. Firstly, the working principle of the planar antennas and the theory of the Ant Colony Optimization are analyzed. Next, the description of the working principle of the Electromagnetic Bandgap and generally physical phenomena accompanying electromagnetic waves propagation in a periodic medium are given. In the second part of this thesis, the ACO was implemented into the VBA language, and was applied to two models of planar antennas. These models were created in the CST Microwave Studio. After an optimization of the antennas the results were evaluated, and the optimization of one of the antennas was compared to the optimization methods in CST Microwave Studio. Then, the standard substrate of the second model was replaced by the EBG substrate, and the results were confronted. Two types of EBG lattice were used. The design procedure of the square lattice was described, and the dispersion diagram was created in the CST Microwave Studio. In the final part of thesis, the verification of the results was carried out in Ansoft HFSS, and the results from both simulation programs were compared to each other.
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Broadband linear antenna array for BAN applications
Gaja, Tomáš ; Kufa, Martin (referee) ; Puskely, Jan (advisor)
The work deals with the design and the practical realization of a single element of antenna arrays and with the simulation of all elements of antenna arrays for application in BAN. The main attention is focused on the shaping of radiation pattern with suppression of unwanted side lobes. Based on these principles the script was created in MATLAB environment which effectively analyses features of each desired antenna array. The next section of this work is focused on design of narrowband Patch antenna and broadband Vivaldi antenna in frequency band ISM 5.8 GHz and supply network for antenna arrays. Designed antenna arrays were verified in simulator of electromagnetic field CST including their function and features in proximity of human tissue. These simulations were experimentally made only for a single element of antenna arrays. The results from measured radiation pattern were analyzed in script as array about eight elements.
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Energy harvesting demonstrator
Kaděra, Petr ; Mikulášek, Tomáš (referee) ; Mrnka, Michal (advisor)
This semestral thesis is focused on radio frequency energy harvesting. The thesis describe parts of network that are essential for conversion of radio frequency energy into DC. It deals with various solutions to the given problem. The aim of the thesis is to design a proper antenna with supplemental circuits for commercial Powercast P2110B receiver which combines the function of a rectifier and a step-up DC/DC converter.
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Electrically conductive surfaces for 3D printed structures
Šomšák, Martin ; Mikulášek, Tomáš (referee) ; Láčík, Jaroslav (advisor)
This thesis describes the technical possibilities of coating various 3D printed structures by different coating methods. Different surface structures have been created on two models for two 3D printing technologies. Antennas on FR4 and PLA substrates were simulated. After adjusting the dimensions of the antennas in the simulations and the results obtained from the simulations, two speckle antennas on PLA substrate were created. To form the antennas, the substrate was coated with copper foil and electrically conductive spray. Subsequently, the antennas were measured, and the results were compared with the simulations.
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Circularly polarized antenna optimization
Niederle, Vojtěch ; Poměnková, Jitka (referee) ; Kadlec, Petr (advisor)
Tato práce se zabývá optimalizací pomocí Gaussových procesů, algoritmu diferenciální evoluce a její implementací v prostředí MATLAB. Teoretická část se zabývá tématem Gaussových procesů z hlediska matematické reprezentace, volby jádra, parametrů, matematických postupů pro implementaci, algoritmem diferenciální evoluce, mutací, křížením a teorií kruhově polarizovaných antén. Praktická část popisuje implementaci v prostředí MATLAB a zabývá se testováním tohoto algoritmu na testovacích funkcích. Výsledky jsou pak porovnány s jinými stochastickými optimalizačními algoritmy a je diskutována efektivita metody pro různé typy problémů. Na základě výsledků je metoda rozšířena o algoritmus diferenciální evoluce a je provedena optimalizace kruhově polarizované antény. Navržená anténa je vyrobena a změřena, výsledky jsou porovnány se simulacemi.
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3D printed circularly polarized patch antenna
Drápal, Jakub ; Kaděra, Petr (referee) ; Láčík, Jaroslav (advisor)
The bachelor thesis deals with circularly polarized patch antennas. In this work, circular polarization is achieved by inhomogenous substrate. The first part summarizes the basic theoretical knowledge about the patch antennas, the shapes of the patch antennas, the excitation methods and the generation of circular polarization. In the next section, the design of a circularly polarized patch antenna on an inhomogeneous substrate is described, and several antenna concepts are proposed and compared with each other and with a conventional antenna. The effect of shaping the inclusions and their gradation in the substrate and the insertion of the inclusions around the centre conductor in the substrate is investigated. The last section is devoted to the realization of the designed antennas by 3D printing method and comparison of simulations from ANSYS HFSS software with measurements of the antennas.
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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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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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