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Antennas for milimeter-wave bands
Pítra, Kamil ; Svoboda, Petr (referee) ; Raida, Zbyněk (advisor)
This thesis describes design and experimental verification of three types of the wideband antenna Bow-tie antenna, Vivaldi antenna and Spiral antenna. The tracked parameters are bandwidth, input impedance, gain and directivity patterns. Next step is design of millimeter-wave horn antennas. Attention is turned to the proper construction of a wideband feeder of the horn. For the final antenna structure, a bow-tie dipole and a Vivaldi antenna were chosen. The antenna construction is aimed to provide a wide bandwidth on one hand and a high gain on the other hand.
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SIW-Based Circularly Polarized Antenna Arrays
Špůrek, Jan ; Joler,, Miroslav (referee) ; Mazánek, Miloš (referee) ; Raida, Zbyněk (advisor)
Tato disertační práce prezentuje nový koncept kruhově polarizovaných anténních řad na bázi vlnovodu integrovaného do substrátu. Hlavní devízou konceptu je modularita, kdy je základní stavební blok řady použitelný pro tvorbu komplexnějších řad a tento blok zároveň slouží jako šablona pro návrh komplexnější struktury. Anténní řada byla simulována a experimentálně ověřena pro frekvence 17 a 60 GHz. Na základě dosažených výsledků byla odvozena metodologie pro návrh a identifikovány klíčové oblasti návrhu. Následně práce představuje techniku zvýšení šířky pásma osového poměru kruhově polarizovaných anténních řad pomoci parazitních flíčků, které jsou umístěny nad zářiče v definované vzdálenosti. Anténní řada z první části práce byla použita v simulacích a experimentálním ověření pro frekvence 17 a 60 GHz, kdy byla tato řada rozšířena o parazitní strukturu, přidávajíc další vrstvu modularity do konceptu.
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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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Stacked Yagi antenna for 60 GHz frequency band
Janečka, Martin ; Polívka, Milan (referee) ; Raida, Zbyněk (advisor)
This diploma thesis deals with the design and simulation of multi-layer stacked Yagi antenna at the frequency of 60 GHz. At work are proposed and compared two ways of antenna feeding methods. Based on the results obtained, antenna is fed by substrate integrated waveguide. The proposed antenna has been optimized in terms of gain and impedance matching at the specified frequency. The correct functionality of the antenna was verified by simulation program CST MWS 2011. Simulation results were verified experimentally.
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Planar antennas with special superstrates
Zdráhal, Roman ; Oliva, Lukáš (referee) ; Horák, Jiří (advisor)
This diploma thesis deals with the modeling of planar antennas with special superstrates in the CST Microwave Studio. Attention is given to the electromagnetic bandgap (EBG) substrates. Firstly, the working principle of these special substrates and generally physical phenomena accompanying electromagnetic waves propagation in a periodic medium are analyzed. By modeling of basic EBG structures in CST their dispersion diagrams were obtained and afterwards compared to one another. The object of the second part of this thesis was modeling of a chosen antenna in CST. An Antenna placed first on the conventional and then on the EBG substrate - in both cases with special superstrates - is analyzed and compared to each other. In the third part of this thesis, the particle swarm optimization (PSO) technique was implemented in CST (VBA language), and was applied to the original design of the chosen antenna. In the final part of this thesis, the optimized antenna was modeled and analyzed in ANSOFT HFSS, and the results from both simulation programs are compared to each other.
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Planar antenna arrays for RFID applications
Pochobradský, Jakub ; Horák, David (referee) ; Lukeš, Zbyněk (advisor)
This thesis describes the basic principles of radio frequency identification, basic characteristics of patch antennas, the possibility of their feeding and design of planar antenna series. Are discussed, impedance matching options. The selected antenna arrays were realised, measuring their parameters was down and measured parameters was compared with simulation results.
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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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Miniature antenna for mobile applications
Šmarda, Marek ; Švanda,, Milan (referee) ; Pokorný, Michal (advisor)
This work deals with the most famous constructions of planar antennas. The work analyses selected methods of connecting planar antennas' charging with the possibility of impedance adaptation. An important part of the work consists of description of techniques for increasing bandwidth and conversely techniques for reducing the dimensions which are important for the design of planar antennas for mobile devices. The antennas were designed by means of theoretical basis and their properties were examined in the electromagnetic field simulator. The selected antenna model was constructed and its parameters were measured experimentally. The matching circuit for the antenna to tune it to different resonant frequencies was designed and constructed.
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Dualband Antenna for Global Navigation Satellite System
Mikulášek, Tomáš ; Lukeš, Zbyněk (referee) ; Láčík, Jaroslav (advisor)
This master’s thesis introduces to the reader with a modern antenna type the microstrip patch antennas. The most common types of microstrip antennas and their parameters and feeding methods are introduced in the theoretical section of this master’s thesis. This section deals with the circularly polarized microstrip antennas. Design of an active dual-band circularly polarized antenna for global navigation satellite application in the AWR Microwave Office is presented in the practical section. The proposed single-fed dual-band circularly polarized design is achieved using two stacked square microstrip patches. The antenna operates at the L1 + E1 and L5 + E5a frequency bands. Antenna preamplifier consists of a low-noise transistor and a dual-band band-pass filter. The thesis describes realization and measurement results of the dual-band antenna performance in the anechoic chamber. Measured results of the preamplifier performance are presented.
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Reconfigurable patch antenna
Zlatníček, Radek ; Polívka, Milan (referee) ; Raida, Zbyněk (advisor)
The master's thesis deals with the design and implementation of a reconfigurable patch antenna. The antenna is fed by a microstrip transmission line. To the microstrip feeder, tuning stubs are connected. Each stub matches the input impedance of the antenna to 50 ? for different operation frequencies. Stubs can be individually connected to the feeder by PIN diodes; operation frequency of the antenna can be switched that way. In the project, the antenna is initially designed for antenna substrate RO3006. Then, the design will be converted to the substrate ARLON AD600 selected for the realization. In the project, modifications of stubs will be proposed to properly connect the PIN diodes. Functionality of the designed antenna will be verified by modeling in Ansoft Designer. The last part will be dealt with implementation of the antenna and the experimental measurement of their properties.
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