National Repository of Grey Literature 115 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
3D printed directional antenna
Dvořák, Václav ; Horák, Jiří (referee) ; Láčík, Jaroslav (advisor)
This master thesis deals with a study of directional antennas, followed by their design and optimization of horn antenna based on SIW for Ka band (26,5- 40 GHz). The first part of the thesis contains the theoretical analysis of the different types of directional antennas, also the SIW technology is described here. It also describes the 3D printing technology by means of which the final antenna should be made. The next part of this work is about design of horn antenna based on SIW. Simulation and optimization of the antenna will be done using the CST Microwave Studio. The horn antenna was modeled with three different dielectric loads. The horn antenna with an experimental triangular dielectric load was chosen for fabrication. The fabricated antenna has reached almost the whole bandwidth to cover Ka. The antenna gain was 9,38 dBi for 33 GHz frequency.
3D printed directional antenna
Dvořák, Václav ; Horák, Jiří (referee) ; Láčík, Jaroslav (advisor)
This master thesis deals with a study of directional antennas, followed by their design and optimalization of horn antenna based on SIW for Ka band (26,5- 40 GHz). The first part of the thesis contains the theoretical analysis of the different types of directional antennas, also the SIW technology is described here. It also describes the 3D printing technology by means of which the final antenna should be made. The next part of this work is about design of horn antenna based on SIW. Simulation and optimization of the antenna will be done using the CST Microwave Studio. The final part of the thesis deals with evaluation of achieved results.
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.
Financing the Construction og a Low Energy House
Horák, Jiří ; Tománek, Jindřich (referee) ; Zeman, Václav (advisor)
This thesis describes the design of optimal options for financing the construction og a low energy house. In the introductory section describes the characteristics of the two products designed to finance housing, mortgage loan and building savings. Another section is devoted to the characteristics and principles of construction of a low energy house, which is related to low energy and less than saving the house. The final section focuses on the selection of a suitable vision of the comparable financial products.
A one-parametric formula relating the frequencies of twin-peak quasi-periodic oscillations
Török, G. ; Goluchová, K. ; Šrámková, J. ; Horák, Jiří ; Bakala, P. ; Urbanec, M.
Timing analysis of X-ray flux in more than a dozen low-mass X-ray binary systems containing a neutron star reveals remarkable correlations between frequencies of two characteristic peaks present in the power-density spectra. We find a simple analytic relation that well reproduces all these individual correlations. We link this relation to a physical model which involves accretion rate modulation caused by an oscillating torus.
Epicyclic oscillations of thick relativistic disks
Horák, Jiří ; Straub, O. ; Šrámková, E. ; Goluchová, K. ; Török, G.
We study epicyclic oscillations of thick relativistic tori with constant specific angular momentum distribution using the finite element numerical method. We have compared frequencies of the axisymmetric and non-axisymmetric modes with the analytic formulae obtained by Straub and Šrámková (2009) and Fragile et al. (2016). We have found excellent agreement in the case of axisymmetric radial epicyclic modes. In the case of the axisymmetric vertical epicyclic modes and non-axisymmetric modes in general, the analytic approximation agrees with numerical results only for tori of moderate thicknesses. Our analysis also revealed an instability of the thick constant angular momentum tori with respect to the radial epicyclic oscillation.
Wave excitation at Lindblad resonances using the method of multiple scales
Horák, Jiří
In this note, the method of multiple scales is adopted to the problem of excitation of non–axisymmetric acoustic waves in vertically integrated disk by tidal gravitational fields. We derive a formula describing a waveform of exited wave that is uniformly valid in a whole disk as long as only a single Lindblad resonance is present. Our formalism is subsequently applied to two classical problems: trapped p–mode oscillations in relativistic accretion disks and the excitation of waves in infinite disk.
X-ray spectroscopy of polar-scattered Seyfert 1 galaxies
Mikušincová, Romana ; Svoboda, Jiří (advisor) ; Horák, Jiří (referee)
In this thesis we present a spectral re-analysis of the Fairall 51 galaxy. It is optically a Seyfert 1 galaxy. It does, however, show a very strong polarization in the optical spectrum and as this feature is not characteristic for Seyfert 1 objects, this galaxy may represent a borderline object between Seyfert 1 and Seyfert 2 galaxies and provide with valuable information about the structure of Active Galactic Nuclei. We studied two archival sets of observations performed in September 2005 and March 2006 by the European satellite XMM-Newton and four observations performed in September 2013 by the Japanese observatory Suzaku. It follows from the spectral analysis that there are at least two or three ionized absorbers in the studied AGN. Based on the spectral variability, we were also able to estimate the location of the variable absorber which appears to be 3 to 60 light days from the central engine, which indicates its origin in the Broad Line Region. 1
Quasar accretion disk mapping by gravitational microlensing
Ledvina, Lukáš ; Heyrovský, David (advisor) ; Horák, Jiří (referee)
Quasar microlensing is a relatively newly explored phenomenon, which is ideally suited for studying the spatial distribution of emission from the innermost accretion disc. By now we know many macrolensed quasars, in which we can observe multiple images formed by the deflection of light in the gravitational field of an intervening galaxy. In case one of these images passes directly through the stellar population of the galaxy, it can be additionally microlensed by individual stars. The gravitational field of these stars forms a caustic network for light passing by. When a quasar accretion disc crosses behind this network, induced changes can be observed in the light curve as well as in the spectrum. In the first part of this thesis we study the statistics of the time intervals between successive caustic crossings. In the second part we use a fully relativistic Kerr-metric thin-disc model for studying the light curve of a fold-caustic crossing and its dependence on the accretion- disc parameters. In the last part we simulate changes in the X-ray iron-line profile during a fold-caustic crossing. We find characteristic spectral features formed on the line, and derive their analytical description. Finally, we map the maximum strength of microlensing-generated peaks on the spectral line for different...
Substrate integrated dielectric resonator antenna
Jedlička, Lukáš ; Horák, Jiří (referee) ; Mrnka, Michal (advisor)
The bachelor´s thesis deals with the design of the dielectric resonator antenna in the microwave band X, where the resonator is made by air perforations. The antenna is made by two layers. The antenna is supplied by the substrate integrated waveguide. The design of the dimensions to achieve the desired resonance frequency of the dielectric resonator and integration of resonator is described. The whole antenna is designed in the CST Microwave Studio software.

National Repository of Grey Literature : 115 records found   1 - 10nextend  jump to record:
See also: similar author names
7 HORÁK, Josef
3 Horak, J.
3 Horák, J.
11 Horák, Jakub
30 Horák, Jan
4 Horák, Jaroslav
7 Horák, Josef
30 Hořák, Jan
2 Hořák, Jaromír
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