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Low-profile directional antenna
Žúrek, Dan ; Pítra, Kamil (referee) ; Láčík, Jaroslav (advisor)
This diploma thesis deals with a study of low-profile directional antennas, followed by design and optimization of parabolic reflector antenna in centimeter and millimeter band. The first part of this work is focused on the analysis of several kinds of directional antennas, mainly on parabolic reflector and on SIW technology, which will be used for final antenna realization. The next part of this project is about the particular concept of the substrate integrated parabolic antenna for 60 GHz ISM band, its simulation and optimization in the CST Microwave Studio software. The final part of this thesis is devoted to the results achieved.
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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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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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Microwave planar circuits design and fabrication
Šamořil, Lukáš ; Láčík, Jaroslav (referee) ; Mikulášek, Tomáš (advisor)
The bachelor‘s thesis deals with planar microwave circuits especially directional couplers and microwave power dividers. First, the thesis describes about microwave circuits and directional couplers and then about power dividers microwave. Types, properties, principles of operation and design of these circuits are described in more detail. Further, the work is devoted to the specific design, the simulation and the optimization of the hybrid ring directional coupler divider and Wilkinson’s divider operating at the frequency 1.5 GHz. Those two microwaves circuits are fabricated and the measured results are compared with simulated results. The circuits will be used in a student's laboratory.
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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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Modeling of log-periodic planar antenna
Martiš, Vítězslav ; Pokorný, Michal (referee) ; Láčík, Jaroslav (advisor)
The content of this work is a analysis of the project method and a simulation of planar logarithmically-periodic antenna. The simulation verified effects of main antenna-dimensions on her function. Through the use of results was designed acceptable antenna, inclusive of supply circuit. This was remitted to simulation
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Textile Microwave Components
Hotovec, Jakub ; Láčík, Jaroslav (referee) ; Vašina, Petr (advisor)
This bachelor thesis is focused on possibilities of designing components integrated on substrate, where substrate is fabric. It contains theoretical information about the SIW structure, measurement of dieletric parameters of three fabrics, design, synthesis and production of waveguide, a three port divider and a band-pass filter on three substrates. For simulation CST Microwave Studio is used
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Circuit Parameters Measurement by S parameters - Laboratory Experiment
Karniš, David ; Láčík, Jaroslav (referee) ; Urbanec, Tomáš (advisor)
Bachelor thesis describes a method of measuring impedance suitable for determining the properties of RF and microwave circuits. The main objective is to get acquainted with S parameters, method of measuring them with vector analysis and with equivalent circuits of passive elements. Further is discussed the issue of calibration and its parts. The following section describes the product design process, concluded by verification of measuring method and design.
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Periodic structure design for directivity enhancement of dielectric resonator antennas
Slavíček, Radek ; Horák, Jiří (referee) ; Láčík, Jaroslav (advisor)
The thesis deals with linearly polarized dielectric rectangular resonator antenna (DRA) operating in the basic mode TEy11 and higher order mode TEy131 at f0 = 10GHz surrounded by an electromagnetic band gap structure (EBG). The dielectric resonator antennas, the EBG structure were designed and a method of integration of both components was developed. The simulated results show a significant improvement of the radiation pattern in the E-plane radiation pattern (narrower main beam, lower level of side lobes, higher directivity) in comparison to a conventional DRA. This was verified by the TEy11 measurement.
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Coaxial probes for permittivity measurement of materials
Hub, Michal ; Urbanec, Tomáš (referee) ; Láčík, Jaroslav (advisor)
This bachelor thesis deals with the measuring complex permittivity of dielectrics using a coaxial probe with an open end in the frequency range of 300 MHz to 3 GHz. It is non-invasive measurement method can be widely used during the research of dielectrics. There are describe various approaches to coaxial probe design with respect to the expected size of complex permitivity in this work. Based on the studies available materials was proposed several probes with a focus on the method of measuring the low-loss dielectrics with help reflective plate. The probes were simulated to measure the reflectance in Design CST MICROWAVE STUDIO. Thereof can calculate the value of complex permittivity. This document lists only those probes that show good results and are prerequisite for the realization of practical measurement.
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