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Antenna for universal transmitter
Daněk, Jan ; Láčík, Jaroslav (referee) ; Láčík, Jaroslav (advisor)
This work describes an electrically small antennas used for mobile devices in the ISM band. The aim of this work is to select an antenna for a universal transmitter/receiver working in the 868 MHz band. The work contains description of the universal transmitter/receiver, and a list of suitable antennas. Tolerance analysis is performed by numerical model. The proposed antenna is manufactured and measured.
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Substrate integrated waveguide filter
Vyskočil, Jiří ; Tkadlec, Roman (referee) ; Láčík, Jaroslav (advisor)
In this thesis is discussed a filter design of a band-pass substrate integrated waveguide filter on the frequency of 5 GHz. It also includes design theory, filter synthesis, filter analysis in the program CST Microwave Studio® and the results of measurement on a vector network analyzer. The analysis results are compared with the measured results. Good agreement between simulated and measured results is observed.
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Automotive antenna for mobile communications
Porč, Jan ; Láčík, Jaroslav (referee) ; Pokorný, Michal (advisor)
This thesis deals with design of flush–mounted planar disc antenna suitable for use in vehicles. For each of the bands GSM900 and GSM1800, which are used in Czech republic, an independent antenna has been created. As a simulator of the electromagnetic field the program IE3D has been used. For the improvement of theoretical results an optimisation in the program MATLAB has been developed. As the optimisation method the genetic algorithms have been selected.
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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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Computer design of a digital radio link
Havel, Ladislav ; Nováček, Zdeněk (referee) ; Láčík, Jaroslav (advisor)
The Terrestrial digital radio links are used for transmitting digital information between fixed stations on a line of sight of a radio path. Each digital radio link has many characteristics and parameters for transmission. We require technical parameters in the design of digital radio link such as data rates and capacities. In this design we should take into account most effects of the electromagnetic waves propagation, if we want to meet user technical requirements of the link and if that link may correctly transmit digital signals with minimum errors. Prediction methods for the design of terrestrial line of sight systems are still in progress. Some effects of electromagnetic waves propagation and methods of the digital radio link design depend on natural variability and climate. The goal of this diploma thesis is to investigate methods for the design of terrestrial line of sight links with taking into account of ITU recommendation. Make computer program which implement this investigate methods
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Implementation and Test of a 2D-integral-equation MoM-algorithm for the Analysis of Power-Bus Structures on Printed Circuit Boards
Štumpf, Martin ; Láčík, Jaroslav (referee) ; Leone, Marco (advisor)
Tato práce se zabývá analýzou power-bus struktur využitím metody založené na formulaci problému 2D hraniční integrální rovnicí ve frekvenční oblasti. Uvedená metoda byla implementována v Matlabu. Program umožňuje analyzovat obecné polygonální power-bus struktury s možností nastavení parametrů substrátu a libovolného počtu a umístění budících portů. Výstupem programu je frekvenční závislost rozložení elektrického pole mezi deskami struktury, vztahy mezi porty struktury vyjádřené např. impedanční maticí a vyzařovací diagram. Dále byla implementována možnost převodu výsledné impedanční matice do tzv. Touchstone formátu, pomocí něhož je možné modelovat analyzované struktury jako obecné N-porty (např. v ANSOFT Designeru), což umožňuje analýzu power-bus struktur s dalšími obvodovými prvky. Výsledky byly ověřeny pomocí existujících analytických vztahů pro jednoduché obdélníkové struktury, využitím komerčního simulačního programu a praktickým experimentem.
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Modeling of planar coupling circuits
Valošek, Josef ; Puskely, Jan (referee) ; Láčík, Jaroslav (advisor)
This master’s thesis deals with modelling of the planar coupling circuits, namely type of the wideband couplers and the ultra-wideband couplers. The purpose of this thesis is an analysis, a synthesis, a numerical modelling and a fabrication (only chosen types) of the presented couplers. All of the couplers works on medium frequency f0 = 7 GHz with coupling C = 3 dB. Types of the substrate are Arlon 25N and Arlon AD600. EM simulator IE3D and circuit simulator in program Ansoft Designer are used for the numerical modelling. The realized wideband couplers were measuring by the vector analyzer Agilent E3864B.
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Design of circular polarized antenna for 2.4 GHz
Hase, Michal ; Lukeš, Zbyněk (referee) ; Láčík, Jaroslav (advisor)
In this thesis, I introduce two types of circularly polarized rectangular microstrip antennas at 2.44 GHz. First type has direct fed and the second has two inputs for fed. In first case is used a stub to make the frequency with minimum return loss and equal to the frequency with minimum axial ratio. In second case is use the power splitter to divide the wave in to two lines with phase shift 90° for feeding the patch. In this thesis is described, how to get the best results of Axial Ratio.
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Radiation of antenna array in near-field area
Hermany, Jiří ; Láčík, Jaroslav (referee) ; Nováček, Zdeněk (advisor)
The aim of my diploma thesis is to analyze the antenna array radiation and to produce the antenna array radiation computation program. The program should display the electric and magnetic intensity and radiation power density distribution over the planar or cylindrical surface in the near-field area. The antenna array analyzed in this paper consists of a number of elementary dipoles placed in a row with a reflector which represents the conductive board situated in parallel to the row of dipoles. The demonstration program was built in MATLAB and allows computing and displaying the computed values components of antenna array radiation on the planar or the cylindrical surface. The program also allows saving computed values, saving displayed graphs, or saving the adjusted parameters of antenna array. The created program can be used for the presentation of the antenna array radiation in a school laboratory or for the graphical representation when a new antenna is designed.
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Design of log-periodic antenna
Kliha, Marek ; Nováček, Zdeněk (referee) ; Láčík, Jaroslav (advisor)
This diploma thesis deal with the design of log-periodic antenna. The log-periodic antenna is self-complementary and broadband antenna. Antenna self-complementary structures are described only by angles. Input impedance of log-periodic antenna is equal to theoretical impedance ohms. The input impedance and radiation patterns of broadband antenna structures are independent of frequency over theoretically unlimited bandwidths. The log-periodic antennas provide linearly polarized radiation pattern. In this thesis is designed antenna for bandwidths 1 to 5GHz. In this diploma thesis is introduced design balanced unit, this is compound broadband balun and broadband impedance transformer. The broadband balun is based on conversion of microstrip line to balanced stripline. The Klopfenstein impedance taper is used for design. For simulation was used software from firma Zeland software IE3D.
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