The work addresses the unusual proposal feed for parabolic antenna with circular polariza-tion signal. This is a modified waveguide feed, waveguide polarizer with a septum. Contemporary RHCP and LHCP wave occurs in several applications of microwave commu-nication and measurement system. From this point of view the septum polarizer can be useful. The septum polarizer is a four-port waveguide device. The square waveguide at one end con-stitutes two ports because it can support two orthogonal modes. A stepped septum divides the square waveguide into two standard rectangular waveguides sharing a common broad-wall. The size of the septum as well as two versions of the waveguides excitation were analyzed and are described in this paper. Ansoft HFSS is software for design and simulation of feed. This software can visualize not only the specified model feed, but also the course of electromagnetic field in feed and over time.

The work deals with the design and experimental production of the model type Birdcage coil used for magnetic resonance imaging system (MRI). The work deals with the design and behaviour of the model type Birdcage coil volume designed for imaging system for magnetic resonance imaging (MRI). Volume coils are generally very useful for use in MRI, because in transversal design allow easy access into the cavity when the flow vector of magnetization. The aim of the work was to construct a numerical model of transversal coil type Birdcage of the predefined dimensions. The created the coil tuned the desired resonant frequency having regard to maximize performance in the measured sample migrated. The modeling coil experimentally produced and measurements also confirm the accuracy of the numerical model.

The work is focusing on dynamic effects of short-circuit currents, more precisely dynamic effects of short-circuit currents on switchgear cabinet (terminal box). The work was designated to a concrete construction type of two switchgear cabinets located on rotating machines via company Siemens Electric Machines Drásov s.r.o.. The switchgear cabinets are designed for non-explosive environment where the air is used as an insulating medium. The task was to determine how the device will behave during the three-phase short-circuit and three-phase short-circuit with earth/ground connection. The following programs were used for the calculations and simulations: Ansoft Maxwell 16.0, Ansoft Maxwell 2015 and ANSYS Workbench 16.0. By using these programs the effects of forces which acts on current paths in cabinet caused by the passage of short-circuit current were simulated, statically and also dynamically. Further the effects of pressure acting on cabinet frame during the arc short-circuit have been statically and dynamically simulated. All the results are summarized in the conclusion. Conclusion also contains the final evaluation of the functionality of both switchgear cabinets.

The master thesis is focused on the simulation of the toroid coils in Ansoft Maxwell 3D software, which uses finite element method for electromagnetic field simulation. Firstly the process creation of the geometric model toroid coil with seventy-five threaded is presented. It is necessary to debug this model and prepare it for the mesh generation. Physical properties are assign to this model and it gives rise to the physical model. We will set boundaries, excitation current, core material, winding material and the parameters for the mesh generations. New material Kashke K4000 will be created in the materials library and subsequently we will define its BH curve on the basis of datasheet. Analysis is made in two modes. Direct currents (7,5A; 10A; 15A; 20A; 25A) and (non)linear materials are used in magnetostatic solution. Toroid coil is excited by current pulse in transient solution. In Ansoft Maxwell Circuit editor a source which generates current pulse will be created. This excitation will be assigned to the toroid coil as an extern source through a terminal. Core material is linear in the case of transient analysis, because Ansoft Maxwell 3D doesn´t allow to use nonlinear material in this solution. Settings are different in transient and in magnetostatic analysis. End time and time step are entered to solve this task in transient analysis. Time points are entered too. Flux density and electromagnetic field strength are calculated in these time points and later it will be possible to view the results. Calculated fields are shown as the pictures in this thesis. The procedure how to use a field calculator in the postprocessing is given as well. The achievements are summarized in the conclusion.

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.

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.

This thesis describes complex modeling of asynchronous motor by finite element method. Complex modeling concerns to making models based on different physical principles and their connection. Models are made in Ansys program components and their connection is made in program Ansys Workbench. This thesis includes creating electromagnetic model, thermal model, mechanical model and coupled model which connect partial models.

Práce se zabývá výpočty magnetických a tepelných vlastností servomotoru s permanentními magnety (motor M718 I vyráběný firmou VUES s.r.o. v Brně). Všechny uvedené výpočty jsou založené na numerických metodách konečných prvků a konečných objemů. 2D magnetická analýza motoru byla řešena s pomocí programu FEMM, zatímco pro 3D analýzu byl využit software ANSOFT. Magnetické analýzy umožnily stanovit rozložení magnetického pole v motoru a ve vzduchové mezeře. Ztráty způsobené vířivými proudy byly počítány v závislosti na rozměrech permanentních magnetů a velikosti toku magnetické indukce ve vzduchové mezeře. U 3D modelu v programu ANSOFT byly vypočítány i Joulovy ztráty. Pro daný servomotor byly navrženy dva způsoby chlazení. V prvním případě se jedná o vnitřní chladicí systém. K původnímu modelu motoru byly přidány některé modifikace (otvory v rámu motoru a radiální ventilátor na hřídeli uvnitř rámu motoru). U druhého způsobu chlazení bylo navrženo vnější chlazení. K původnímu rámu byly přidána chladicí žebra a radiální ventilátor na hřídeli vně rámu motoru. Výpočty proudění a tepelná analýza byly provedeny jak pro původní model motoru, tak i pro modifikovaný návrh (vnitřní a vnější chlazení) pomocí software ANSYS Workbench. Teplotní charakteristiky původního motoru byly měřeny různými senzory. Bylo provedeno porovnání experimentálně získaných výsledků s vypočteným teplotním modelem. Práce byla vytvořena v rámci doktorského studijního programu Elektrotechnika a komunikační technologie, obor Silnoproudá elektrotechnika a elektroenergetika. Podstatná část práce vznikla za podpory Centra výzkumu a využití obnovitelných zdrojů energie a výzkumných projektů CZ.1.05/2.1.00/01.0014 and FEKT S-11-9.

The dissertation thesis deals with a study of an influence of a simultaneous incidence of an additive thermal noise and a multiplicative phase noise on the useful signal transmission in narrowband satellite communication systems. While the additive thermal noise affects the useful signal only on the receiver side of the communication system, the multiplicative phase noise is produced in all system oscillators. One investigates how the receiver filter bandwidth reduction takes effect on the influence of individual noise types. The thesis is divided into four units. The first one (chapters 4 and 5) solves the ways of modeling of both noise types. In the second part (chapter 6), on the simple example, the primary analysis of the phase noise influence is made. Basic modulation schemes used in the satellite communication are also discussed (chapter 7). Third part (chapter 8) is devoted to the modeling of a general digital system with a M PSK modulation made directly on the main carrier wave. The last part (chapter 9) describes the modeling of a digital system with a BPSK modulation on the auxiliary subcarrier wave followed by an SSB modulation on the main carrier wave. General conclusions are deduced from obtained simulation results.