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Near field of the dipole antennas
Beran, Vlastimil ; Tkadlec, Roman (referee) ; Nováček, Zdeněk (advisor)
The thesis describes the radiation of dipole antennas in near field area. More methods for evaluation of spatial dipole field arrangement are compared. The work target for practical use is to create software for simulation of near field values placed in planar or cylindrical observation plane. The computer programme is applicable to single dipole or dipole array. The limits for human body exposition of non-ionizing radiation are here implemented for compliance purpose in hygienic evaluations. The simulated results of field distribution are possible to display as graphs or save to data file. The results of own calculation are compared with results obtained by some commercial software as well by measurement of field components under model conditions.
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Field strength measurement
Novák, Tomáš ; Dřínovský, Jiří (referee) ; Nováček, Zdeněk (advisor)
This thesis is focused on problems of measurement of field intensity especially in short-wave zone of received frequencies. To measure the intensity of electric field, it is necessary to use a suitable antenna whose properties and characteristics/parametres meet best the requirements of this measurement. These requirements are analysed/discussed in the introductory part of this thesis. From these requirements resulted one specific solution which is applicable to this problems. This solution is frame antenna which meets /matches best the requirements of this measurement. Furthermore, a complete suggestion for the frame antenna as well as its calculations were discussed. From individually calculated results graphical functionalities were set together that provided the bases for selection of suitable parameters for frame antenna. Then these bases were verified with similar antenna that was available. In second part of this thesis we modified standard antenna modul RFT FMA11 so that there would be a possibility to use it with any selective microvoltmeter.
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Variable Field Magnetic Force Microscopy
Turčan, Igor ; Nováček, Zdeněk (referee) ; Urbánek, Michal (advisor)
The bachelor's thesis deals with magnetic force microscopy of permalloy discs in an external magnetic field. Main objectives of the thesis are design of an external magnetic field module, preparation of magnetic probes, fabrication of samples and the measurement itself. We prepared functional probes with various magnetic coatings. For the measurement in external magnetic field we fabricated probes with a~layer of magnetically hard Co and for the measurement without external magnetic field we used probes with a~layer of magnetically soft permalloy. Our probes are at least comparable with standard commercial probes. We observed the cores of magnetic vortices, using our home-coated probes with no external magnetic field and also in the external magnetic field. Further, we study the influence of the external magnetic field on nucleation of the cores of magnetic vortices. Experimental techniques used for fabrication and measurement of the samples are briefly summarized.
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Design and optimization of piezoactuators
Jajtner, Jan ; Pavera, Michal (referee) ; Nováček, Zdeněk (advisor)
This bachelor’s thesis main concern is to develop and optimize a linear impact-drive piezoelectric actuator for scanning tunneling microscope working as vertical macroscopic manipulator of the conducting tip. UHV piezoelectric actuator issues are being discussed and analyzed on theoretical level in order to create adequate mathematical model. Based on expressed requirements a prototype is designed and measured, while seeking appropriate parameters of supply pulse and loading.
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Baluns
Beran, Vlastimil ; Puskely, Jan (referee) ; Nováček, Zdeněk (advisor)
The baluns (balanced to unbalanced) circuits are used for connection of symmetrical load (antenna, dipole) to unsymmetrical line (coaxial cable). The balun missing causes the load mismatching to antenna feeder and the antenna parameters degradation as result. There are defined the baluns principle of operation and list of types in this work. The baluns created by short sections lines are the scope of project only. The detailed analysis baluns bandwidth and the type application are described in the second part of project. Several recommendation for baluns design is described as project conclusion including parameters optimalization. The function of the balun was verified by measurement. The relevant results are mentioned in the report end.
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Improvement of control and analysis techniques of a SPM model
Štefko, Marcel ; Nováček, Zdeněk (referee) ; Šulc, Dalibor (advisor)
Bakalářská práce se zabývá zdokonalováním výukového modelu mikroskopu atomárních sil (AFM). Součástí práce je rešerše stávajících analogii mezi makroskopickými jevy a fenomény spojenými s mikroskopii rastrovací sondou. Dále byla vybrána vhodná analogie, která byla následně implementována do již existujícího modelu mikroskopu atomárních sil. Do modelu byl integrován i jednodeskový počítač, který zajistí ovládání i bez nutnosti připojení externího počítače. Na závěr byly vyhodnoceny vlastnosti použité sondy a analogie mezi modelem a skutečnými mikroskopy atomárních sil.
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Automatization of experimental setup for optical spectroscopy
Čecháček, Jan ; Nováček, Zdeněk (referee) ; Dvořák, Petr (advisor)
This bachelor thesis deals with the modernization and improvement of an application that automates measurements on an experimental setup for spectral and topographic mapping using confocal microscopy and near-field microscopy. The arrangement of the report, the principle of communication of the program with individual parts of the report and the principle of data collection and processing are described here. The output of the program are point spectra and 2D maps describing the topography, intensity and position of the spectral peaks. The thesis includes a research study of optical and time-resolving optical spectroscopy and their applications in nanophotonics. The correct functionality of the program is demonstrated by the results of measurements of perovskite MAPbI3 and organic substrate.
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Design of optoelectronic positional sensor
Straka, Radomír ; Nováček, Zdeněk (referee) ; Puskely, Jan (advisor)
The aim of this semestral work is design optoelectronic positional sensor, which can measure current position of measuring line. This position has to be measure very precisely. At first the work describes positional sensors used in automatization. Work study parameters of resistance, inductance, capacity, optoelectronic and ultrasound sensors. Subsequently work choose integrated optoelectronic sensor ADNS-5020, realize with ADNS-5020 circuit for measuring position and realize part processing transmission of signal from sensor to PC with integrated circuit FT232RL. The results of this work are design measuring and transfering circuit for optoelectronic positional sensor, measuring program which have control over designed circuit. Measuring program process measured data of voltage possibly current distribution on the line and create tables and graphs with calculation reflection coefficient and impedance from data.
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Selective hydrogenation of graphene prepared by chemical vapour deposition
Kovařík, Štěpán ; Nováček, Zdeněk (referee) ; Bartošík, Miroslav (advisor)
Controlled bandgap opening is one of the skills necessary for the application of graphene in electronics. The graphene hydrogenation is one of the possible ways to open the bandgap. In this work we deal with local hydrogenation of graphene prepared by chemical vapour deposition on a Si/SiO2 substrate. The hydrogenation was performed by atomic source of hydrogen and polymethyl methacrylate pattern was used for localization of hydrogenated structures on graphene. The pattern was prepared by electron beam lithography. The presence of structures formed by hydrogenated graphene was investigated by Raman spectroscopy, Kelvin probe force microscopy and PeakForce tunneling atomic force microscopy. All three methods have confirmed the local hydrogenation of graphene.
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