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Doble-balanced mixer - laboratory equipment
Dušek, Libor ; Baran, Ondřej (referee) ; Vágner, Petr (advisor)
The aim of this work was double-balanced mixer implementation, which will be used like laboratory equipment. This thesis deals with design of the double-balanced mixer from first theoretical principles to a practical design of a laboratory equipment. For the practical design the integrated mixer SA612 was used. Input signal to the mixer up to 500 MHz frequency can be used. For required operation external oscillator and fifth-order low pass filter were constructed. Oscillator was designed for fixed frequency 32 MHz. Fifth-order low pass filter was inserted between the mixer and the oscillator, because of filtering higher harmonics. The second aim of the work was measuring double-balanced mixer basic parameters, such as Compression Point (P-1dB) and Intercept Point (IP3). For the IP3 measurement, another one device was required. It consists of the power combiner for mixing two frequency close signals and third-order bandpass filter, which selects required frequency band. Finally, the laboratory equipment was fabricated and its real parameters were measured.
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Tuner for UHF Receiver with Low Power Consuption
Kaštánek, Martin ; Vágner, Petr (referee) ; Urbanec, Tomáš (advisor)
The purpose of this work was to make a proposal for input parts of receiver for band 430 to 440 MHz. A model of chosen semiconductor triode BFP540 was created in simulation software. Possibilities how to decrease consumption of this semiconductor triode, keeping the profit, were investigated through the simulation.In compromise consumption, keeping the profit of the amplifier - an optimal operating point for this semiconductor triode UCE = 1,2 V and IC = 2 mA was found. It was tested through the testing wiring with noise microstrips conformity. Ascertained knowledge was used for construction of tuner for UHF receiver. An operating point of input amplifier of UHF receiver was owing to power supply amplifier forced for bigger effectiveness to UCE = 2,65 V and IC = 2,0 mA. Suppression of mirror frequency is provided with Helix filter of the third order, because of intermediate frequency 10,7 MHz. Mixing on intermediate frequency is made again by semiconductor triode BFP540. Selectivity of receiver is provided with intermediate frequency crystal filter 10,7 MHz with bandwidth 15 kHz. Designed input part enables reception of SSB, FM and digital types of modulation.Bandwidth intermediate frequency exit is adapted to this request To receive particular modulation , it is necessary to complete intermediate frequency signal way with appropriate intermediate frequency filter.
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Low noise 70 cm band amplifier
Klügl, Jan ; Vágner, Petr (referee) ; Urbanec, Tomáš (advisor)
This master's thesis is engage in suggestion of low noise 70 cm band amplifier with filter and diode attenuator. At first the thesis describes the basic parameters of amplifier, for example gain, noise figure and dynamic extent. Later in detail describes individual parts, which are the device consist of. At every part of system is mentioned the diagram of connection and values of components, which are ascertained from calculation, simulation and recommendation of producer. The characteristic parameters of amplifier were measured after construction.
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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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MICROSTRIP FILTERS USING DEFECTED GROUND STRUCTURE
Vágner, Petr ; Kasal, Miroslav (advisor)
The thesis deals with the microstrip filter design using defected ground structure (DGS). The difference between standard asymmetric microstrip technique and DGS is in using the structures etched in the microwave substrate ground plane. The DGS resonant characteristics are then used in filter design. The thesis consists of three factual parts. The first one (chapter 4) introduces the use of the DGS resonators in the lowpass filter design. It involves experimental analysis of one type of the lowpass filter. The second part (chapter 5) deals with a novel microstrip lowpass filter design method using DGS. The proposed method is verified by simulations and several samples are realized and measured. Finally, the third part (chapters 7 and 8) deals with the bandpass filter design using specific defected ground structure as a resonator. The resonators are used in a coupled resonator structure. Filters of various orders and resonator configurations are designed and simulated. A combination of the DGS resonators and half-wavelength microstrip resonators is introduced as well. Selected samples are realized and measurement results are compared with simulations.
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Magnetic loop antenna with electronic tuning for frequencies below 30MHz
Burda, Miroslav ; Vágner, Petr (referee) ; Urbanec, Tomáš (advisor)
This project deals with electronic tuning and automated adjustment of magnetic loop antennas, working in the High Frequencys. The whole work is divided into three parts tuning, adjustment and control). The tuning part is realized by changing the capacity of the array capacitors and adjustment is done by different changes of power points. The whole system is controlled by a microprocessor ATmega16. According to utility switches the microprocessor capacity, which tunes the antenna to the required frequency, processes information about power adjustment and autimatically fine-tuning the antenna by changing the position of charging.
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Low-noise amplifier for 145 MHz band
Pivoňka, Rostislav ; Vágner, Petr (referee) ; Baran, Ondřej (advisor)
This work contains a description of low noise amplifier (LNA) working on 145 MHz. This amplifier consists of three parts. They are input circuit, active device and output circuit. The amplifier is designed with transistor BF 998 on substrate FR4. The design and simulations are performed by means of software Ansoft Serenade. The design was completed with the help of design equations and Smith chart methods. The input of amplifier is noisy matched and output of amplifier is matched on impedance 50 ohms. The noise factor in frequency band 144 – 146 MHz is about 0,85 dB. The amplifier gain is in this band circa 16dB.
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Selective Circuits - Laboratory Experiment
Košťál, Stanislav ; Vágner, Petr (referee) ; Urbanec, Tomáš (advisor)
The aim of this thesis is to describe the distribution and behavior of selective circuits and methods for their implementation. There are formulas provided for the calculation of the frequency components of selected second-order RLC filters. It further describes the choice of filter frequency components and computing relationships needed for the construction of coils. The work also includes a description and complete information needed for making measurements of the measurement of the RLC band-pass. The annex to this work includes all the materials needed for implementation of laboratory tasks designed to measure using the product.
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Magnetic Loop Antenna with Electronic Tuning for Frequencies below 30MHz
Svoboda, Luděk ; Vágner, Petr (referee) ; Urbanec, Tomáš (advisor)
The aim of this bachelor's project was realization of a tuning system with complete software and testing of the system's functionality and parameters of antenna. The system is divided into two parts, tuner and controller. The tuner implements change of circuit capacity by switching capacitor series. For switching is used transistor with small transitional capacity but small maximal collector current, too. This parameter restricts the use of system. The second part, controller, uses microcontroller AT89C2051. The microcontroller switches capacitors (and thus sets frequency) according to requests sent from PC with control software. The functionality was checked by tests with network analyzer.
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