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Mini-whip antenna
Pařízek, Tomáš ; Lukeš, Zbyněk (referee) ; Raida, Zbyněk (advisor)
The thesis deals with the impedance matching of electrically very short antennas to the real resistance 50 . The antenna is considered as an input of an emitter follower, which plays the role of the impedance transformer. This follower transforms a large complex input impedance, which is typical for electrically short antennas, to a real output resistance. The output impedance was matched by appropriate matching circuitry to 50 in the frequency band of operation.
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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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RF power meter
Hlaváč, Štěpán ; Jedlička,, Petr (referee) ; Drexler, Petr (advisor)
This master’s thesis describes various principles of measurement of electromagnetic waves in a free space and on a line. Used sensors and their real parameters are given for every method. The analysis of protections of high-frequency inputs of measuring instruments is done here and the most suitable method and protections of input for realization are chosen. The analysis of design of secondary protection of high-frequency input is done in this project. The protection of input is realized and measured. The suitable method of measurement is chosen as well as the sensor for measurement of power. The block diagram and circuit diagram of the meter of power are designed. According to designed conception the measuring instrument for measurement of power is realized and its single qualities are measured during the realization. In the final part its precision is measured and the evaluation of results is done.
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NQR spectroscopy - design of measurement methods
Procházka, Michal ; Bartušek, Karel (referee) ; Steinbauer, Miloslav (advisor)
Nuclear quadropole spectroscopy is a modern analytical method for detecting specific solid state materials, e.g. explosives, drugs etc. It uses phenomenon of atomic nucleus called nuclear quadrupole moment. NQR method is very similar to common nuclear magnetic resonance (NMR) that is why major principles are explained using NMR. The thesis deals with basic principle of NQR, its usage for explosives detection and also detection of other chemical compounds and many other useful applications. The thesis deals with specific circuit design, techniques for sufficient sensitivity, impedance matching and circuit isolation. Practical part consists of simulations as well as designs of a few impedance transformers, pi-networks, and coils. Also experimental probe was created. In the last part, NQR workplace was assembled and a few chemical compounds were detected. These were KClO3, NaClO3 and NaNO2 . Finally minimum detectable amount of potassium chlorate as the strongest signal of these was determined.
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Design and optimization of the helical antenna
Zelinková, Lenka ; Olivová, Jana (referee) ; Lukeš, Zbyněk (advisor)
The thesis contains the design of helical antennas for the assigned frequencies. The theoretical design is verified by parameter calculators. The design properties were verified in the computer simulator CST Microwave studio where the antennas were optimized to the maximum gain. The antennas intended as parabola feeds are completed with the designs of parabolas and focal distances between the antennas and the parabolas. Impedance matching by a quarter-wave transformer is designed for the antennas.
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Ultrasound desintegrator of concrements
Straka, Petr ; Čížek, Martin (referee) ; Rozman, Jiří (advisor)
This thesis is focused on the methodes of crushing kidney’s concrements with continual wave for the frequency 27 kHz and the intensity of ultrasound 10 W/cm2. The main aim is design of the ultrasound head with layer converter and design circuitry. First part of this work describes physical principle of ultrasound, ultrasound waves and methods by which could be remove kidney’s concretions. Practical part of this work is focused on compreshive design of ultrasound crushing system. In the introdiction is analyzed the proposal of applicator and the next step decscribing proposal excitation generator. The work contains results of simulation which was done on proposal curcuit, drawings of scheme, list of components and drawing of PCB.
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Axisymmetric antennas with metamaterials
Roman, Pavel ; Fiala, Pavel (referee) ; Raida, Zbyněk (advisor)
This project is focused on computer modeling of so-called meta-materials, and on the exploitation of metamaterials in the design of electrically small antennas. For modeling, COMSOL Multiphysics 3.3 was used. Simulations were focused on impedance matching of antennas. Antennas with metamaterials were compared with corresponding conventional antennas without metamaterial layers. The project does not investigate the creation of metamaterials; the project concentrates on their influence on crucial parameters of antennas. Next step this project is focused on optimalization this structure in program Matlab version R2009b. We used optimalization method PSO (swarms of particles) and results are comparing whit results calculating in COMSOL program.
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HF and IF circuits of shortwave radiostation
Šnajdr, Václav ; Vágner, Petr (referee) ; Lukeš, Zbyněk (advisor)
The study, description, design and implementation of selected blocks of multiband shortwave radio station are dealt with in the thesis. Focus is placed on the concept of multiband shortwave radio stations, with an emphasis on high frequency and intermediate frequency circuits. The first chapter is devoted to description of the transceiver block diagram which is designed as superheterodyne. The design of bandpass input filters, intermediate frequency crystal filters and output filters is described. Simulation results and the measured characteristics of the implemented functional blocks are presented. Furthermore, the amplifier circuits which maintain impedance matching of individual blocks are discussed. SSB signal generation in the transmitter part of radio station and final stage power amplification are depicted.
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