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Antenna for mobile high power microwave generator
Kračmar, Leoš ; Láčík, Jaroslav (referee) ; Mikulášek, Tomáš (advisor)
The bachelor thesis deals with the design and practical implementation of a magnetron connected to waveguide as an excitation source for a linear slot antenna array. The goal was thorough acquaintance with the issue of partial parts of designs, verification of calculated parameters using software simulations and practical measurements on manufactured parts of the project. In the first part of the work, it theoretically deals with used components, used parameters and by software design of a magnetron to waveguide transition model with practical measurement. The second part of the work contains calculations and simulations of the design of a linear slot antenna array, which continues by series of practical measurements of antenna properties.
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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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Patch antenna array for IFF band
Mička, Josef ; Pítra, Kamil (referee) ; Láčík, Jaroslav (advisor)
This master thesis deals with designing and implementing an antenna array for the IFF band. The design includes an antenna element simulation and a feeding network design for the antenna array. The antenna element is designed as broadband and has an SWR of less than 1.5 in each band. Two stacked patches are used to achieve the required bandwidth. The patches are fed through a slot. An asymmetric stripline line is used for the feeding network. The simulated antenna array shows good impedance matching and gain properties. The final part of the master thesis compares the measured results with the simulated results. Finally, an attempt is made to improve the SWR of the manufactured antenna array.
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Half Mode Substrate Integrated Waveguide Slot Antennas
Hubka, Patrik ; Schejbal, Vladimír (referee) ; Pánek,, David (referee) ; Láčík, Jaroslav (advisor)
This dissertation deals with the research of slot antennas based on a half-mode substrate-integrated waveguide (HMSIW). By using HMSIW, the physical size of the antenna is reduced by approximately half while maintaining excellent antenna performance. The thesis is consists of two factual parts. The first one (Chapter 4) proposes and describes linearly and circularly polarized HMSIW polarized U-slot antenna. The combination of these two antennas resulted in a polarization reconfigurable HMSIW slot antenna. The functionality of all these antennas are experimentally verified. These antennas achieve better performance compared to current developments of the similar HMSIW antennas. The functionality of the linearly and circularly polarized antenna are further investigated in deep by characteristic modal analysis and parametric procedure. Based on those investigations, design guides of those antennas are proposed. The second one (Chapter 5) deals with design and description of the simple circularly polarized HMSIW U-slot antenna array with linear organization of 1 × 4 basic radiators. The experimental verification proved that the antenna array with a simple feeding network achieved the competitive performance in comparison to the similar antenna array described in the literature.
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3D printed antenna with dielectric lens for free-space material characterization method
Horník, Milan ; Láčík, Jaroslav (referee) ; Kaděra, Petr (advisor)
This bachelor´s thesis deals with the free space setup for material permittivity characterization. The workplace includes two horn antennas, two dielectric lenses and sample holder. The work deals with the characteristic properties of materials such as permittivity and permeability. Further, the methods used to determine permittivity are discussed. The next part of the work is focused on a theoretical analysis of the design of a broadband horn antenna with a dielectric lens. The chapter 3D printing and surface treatment deals with the issue of 3D printing and the possibility of applying a conductive layer on the plastic components. The following section presents the calculated and simulated results performed in CST Microwave Studio. In the next chapter, mechanical construction and measurement setup fabrication are discussed. In the end, the achieved results are evaluated.
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Planar mono- and dipole antennas for on-body communication
Maro, Ivan ; Láčík, Jaroslav (referee) ; Raida, Zbyněk (advisor)
This bachelor’s thesis is focused on designing and simulating several types of monopole and dipole textile antennas, which will be used for ON-body communication in ISM 5.8 GHz frequency band. It also examines the possibility of using a reflector made of artificial magnetic conductor to achieve an overall improvement in antenna parameters. The antenna has been subjected to bending, to ensure proper functionality when placed on different parts of the body. For selected antennas, a specific absorption rate SAR was also simulated so that the antenna meets the required limits specified by the competent authorities. Subsequently, two antennas were chosen for prototype production, which were produced by silkscreen printing technique. The manufactured antennas were measured in an anechoic chamber and their results compared with simulations.
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Waveguide-SIW transitions
Bednarský, Vojtěch ; Láčík, Jaroslav (referee) ; Špůrek, Jan (advisor)
This work deals with the design of waveguide transitions. In this work I describe two usually used types of waveguides and that is classical rectangular waveguide with standardized designation WR-10, which is designed for working frequency 94GHz. The second type will be a waveguide integrated into the substrate called SIW. In the first part, numerical models of waveguides are calculated and transitions are created. Numerical models are simulated in CST Microwave Studio. Transitions are constructed in two types. Horizontal transition and orthogonal transition. The results of the first part are obtained dimensions of parameters from numerical models and S-parameters of transition sets.
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Sensing signals of a sensor in digestive tract
Raška, Marek ; Láčík, Jaroslav (referee) ; Raida, Zbyněk (advisor)
Wireless capsule endoscopy (WCE) is a system for capturing images of human digestive tract for medical purposes. The antenna is one of the most important parts of the system. In this report, I present a solution for a system operating in the 2.4 GHz and 915 MHz ISM band. The capsule transmitter contains a conformal loop antenna placed on its outer wall. The planar monopole with a partial ground is used as a receiver. The systems have been verified by numerical simulations with a phantom representing digestive tract. The transmitting modules have the bandwidth of several GHz according to simulations. This allows the antenna to tolerate various effects of living tissues. The receiving antennas have the bandwidth of hundreds of MHz. The path loss of the radio link between antennas operating in 2,4 GHz band is lower than 94 dB for any capsule orientation and location. This does not ensure a sufficient signal strength at the receiving antenna. In contrast, the system operating at 915 MHz ensures sufficient signal level at the receiver.
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3D printed directional antenna
Dvořák, Václav ; Horák, Jiří (referee) ; Láčík, Jaroslav (advisor)
This master thesis deals with a study of directional antennas, followed by their design and optimization of horn antenna based on SIW for Ka band (26,5- 40 GHz). The first part of the thesis contains the theoretical analysis of the different types of directional antennas, also the SIW technology is described here. It also describes the 3D printing technology by means of which the final antenna should be made. The next part of this work is about design of horn antenna based on SIW. Simulation and optimization of the antenna will be done using the CST Microwave Studio. The horn antenna was modeled with three different dielectric loads. The horn antenna with an experimental triangular dielectric load was chosen for fabrication. The fabricated antenna has reached almost the whole bandwidth to cover Ka. The antenna gain was 9,38 dBi for 33 GHz frequency.
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