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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Anténa a nízkošumový zesilovač pro pásmo L / L-band antenna and low noise amplifier

Kučera, Ondřej January 2017 (has links)
This master thesis is dealing with a system for receiving meteorological images from satellites placed on lower orbit. Furthermore it gives basic information about satellites NOAA, METOP and FY. It also includes derivations of equations, that define minimal requirements for receiving antenna and LNA. From reached parametres, energetic balance for connection of the satellite and Earth is calculated. The main part of the master thesis is designing of low-noise amplifier for L band. LNA is implemented on the substrate FR4 and Arlon DiClad 870, circuit is designed with elements of parametres, which are spread out or concentrated. The last part of the thesis describes design of antenna for reception of meteorological images.
22

Multi-Aperture Coherent Change Detection and Interferometry for Synthetic Aperture Radar

Madsen, David D. 09 March 2010 (has links) (PDF)
Interferometry and coherent change detection (CCD) utilize phase differences between complex SAR images to find terrain height and to detect small changes between images, respectively. A new method for improving interferometry and CCD using multiple sub-apertures is proposed. Using backprojection processing, multiple sub-aperture images are created for a pair of flights. An interferogram and coherence map is made from each sub-aperture. For CCD, each sub-aperture coherence map offers an independent estimate of the coherence over the same area. By combining coherence maps, low coherence areas associated with residual motion errors are reduced, shadowed areas are minimized, and the overall coherence of stationary objects between images is increased. For interferometry, combining independent estimates of a scene's height offers a more accurate height estimate. For repeat-pass interferometry, multiple apertures are shown to increase the coverage of valid height estimates. The benefits of multi-aperture interferometry and CCD are shown using examples with real data.
23

Etude et réalisation de filtres matriochkas pour des applications spatiales / Conception and fabrication of matriochka filters for spatial applications

Hallet, Christophe 26 October 2018 (has links)
Le résonateur matriochka est conçu à partir de résonateurs coaxiaux ré-entrants créant ainsi des sauts d’impédances (SIR). La thèse développe alors des innovations théoriques sur la technologie matriochka en proposant des modèles analytiques précis sur le comportement fréquentiel et du facteur de qualité du résonateur. Les modélisations mettent en relief l’existence de degrés de liberté au sein du résonateur matriochka induisant une flexibilité du rapport de forme du résonateur. Les degrés de liberté créent ainsi une multitude de configurations du résonateur matriochka pour une fréquence fondamentale et un facteur de qualité donnés. Par conséquent, une optimisation en volume est réalisée pour concevoir deux filtres en bande L et C afin de minimiser leur encombrement. Une étude de la tenue en puissance dans le vide est également effectuée pour le filtre en bande L. Une méthode conjointe d’optimisation de la tenue en puissance et de minimisation en volume est alors proposée pour ce filtre. Ainsi, les modélisations et les optimisations sont employées afin de concevoir et de fabriquer deux filtres hyperfréquences. Le premier est un filtre de transmission en bande L conçu pour l’application de navigation Galileo qui propose une alternative d’encombrement et une tenue en puissance dans le vide élevée. Enfin, le second est un filtre de réception en bande C conçu, fabriqué et mesuré pour l’application de télémesure qui propose de meilleures performances en réjection et un volume réduit par rapport à l’existant. Finalement, la technologie matriochka est une alternative de résonateur par rapport à l’état de l’art en proposant, selon les configurations, un rejet élevé des harmoniques et un volume réduit pour une fréquence fondamentale et un facteur de qualité donnés. / The matriochka resonator is based on reentrant coaxial Stepped Impedance Resonator (SIR). So, the thesis develops theoretical innovations on the matriochka technology offering accurate analytical models on the frequency and the quality factor behaviors of the resonator. The models prove the existence of degrees of freedom within the matriochka resonator which allows to get different form factors of the resonator. The degrees of freedom create many configurations of the matriochka resonator for a fundamental frequency and a quality factor. Consequently, a volume optimization is realized to design a L-band filter and a C-band filter. A multipactor study is also carried out for the L-band filter. So, a joint optimization method of the multipactor and the volume minimization is proposed for this filter. Thus, the models and optimisations are used in the order to to design and fabricate the microwave filters. The first one is a transmission L-band filter for the navigation application Galileo which offers a volume alternative and a high power in the vaccum. Then, the second one is a reception C-band filter for the telemetry application which offers wide spurious free-performance and a low volume compared to the state of the art. Finally, for a frequency and a quality factor and depending on the configurations, the matriochka technology offers an alternative of the resonator volume, and it offers a wide spurious free- performance and a low volume compared to the state of the art.
24

Konvertor pro příjem digitálních družicových snímků v pásmu L / L-band frequency converter for reception of the digital meteorological images

Bürger, David January 2017 (has links)
Down converter is a mixer which have a three ports. Two ports are refered as input ports and one port is ouput. One input port is connected to a signal which is transmited by meteorological satellites at frequency 1,7 GHz this frequency falls within the L–band. Meteorogical images are trasmited in L-band. The second input port is connected to a local oscillator in this case voltage control oscillator. The output signal includes sum and differential products, for down conversion is logically used differential product. Down conversion is used to convert data that are transmitted at high frequency to lower frequency which can be futher processed and then displayed data on the end device.
25

Výkonové zesilovače v pevné fázi pro pásmo L / Solid State Power Amplifier for the L-Band

Pecen, Vojtěch January 2017 (has links)
The goal of this diploma's thesis is to create a design of a two stages amplifier working in a band reserved for the secondary surveillance radar at the frequency of 1090 MHz. Output power of the amplifier should be 20 W and efficiency should be as high as possible. Because of this the second stage is designed in class C. Contents of this diploma's thesis include a theoretical analysis, simulations of the amplifier parameters, comparison of the Ansys Designer and AWR Microwave Office simulation programs and design of both stages of the amplifier, followed by a comparison of the measured parameters with the simulations.
26

Základní umělecká škola ve Strakonicích / The Primary Art School in Strakonice

DRÁBKOVÁ, Lucie January 2010 (has links)
Primary art schools enjoy a long tradition in our country. The Primary Art School ``Kochana z Prachové{\crqq} in Strakonice celebrates already the 70th anniversary of its foundation. It is surprising that nobody has attempted to elaborate a comprehensive work concerning its history for the whole period. With respect to the fact that I have been teaching the piano playing here since 2006 and therefore I have become a part of it, I have chosen just the history thereof as the subject of my thesis. The Primary Art School participates in many cultural activities of the town of Strakonice and it is an important educational institution because it provides education to 750 pupils in four subjects - the musical, graphic, dancing and literary-dramatic ones and it prepares talented pupils for the study at secondary schools, colleges and universities focused on arts.

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