Academic literature on the topic 'Vysokofrekvenční měření'

Vysoušení stavebních konstrukcí pomocí vysokofrekvenčního elektromagnetického záření (EMW), neboli mikrovlnné technologie (MW), se začíná v praxi stále více uplatňovat. Jedná se o metodu, pomocí které lze nejrychlejším způsobem eliminovat nežádoucí obsah vody ve stavební konstrukci (stěna, stropní konstrukce, atd.). Mikrovlnami je nazývána část elektromagnetického záření o frekvenci 300 MHz až 300 GHz s vlnovou délkou 122 mm. Díky působení MW záření se zobrazí rozdílná homogenita teplotního pole u různých stavebních materiálů. Článek pojednává o změnách fyzikálních faktorů v závislosti na objemu vody a tím i na velikosti hmotnostní vlhkosti daného materiálu (plynosilikát). Dalším z faktorů bude šíření teplotního pole. Šíření bude zobrazováno pomocí termokamery. Měření probíhalo vždy po určitých časových cyklech ozařování.

This master’s thesis describes various principles of measurement of electromagnetic waves in a free space and on a line. Used sensors and their real parameters are given for every method. The analysis of protections of high-frequency inputs of measuring instruments is done here and the most suitable method and protections of input for realization are chosen. The analysis of design of secondary protection of high-frequency input is done in this project. The protection of input is realized and measured. The suitable method of measurement is chosen as well as the sensor for measurement of power. The block diagram and circuit diagram of the meter of power are designed. According to designed conception the measuring instrument for measurement of power is realized and its single qualities are measured during the realization. In the final part its precision is measured and the evaluation of results is done.

Thesis describing design and measurement of the vector reflectometer system based on six port principle. The expectations for precision measurement in wide bandwidth system are explained. Diode linearization problem is described and the calibration method especially designed for the wide band systems is explained. And finally several data processing methods for the final result decision are compared.

The subject of this doctoral thesis is the study of dielectric properties of a binary composite made up of a polymer matrix and metallic filler. Properties of such composites have been extensively examined in the past and they turned out to depend on temperature, frequency and in particular on filler concentration. The objective of this work was first to experimentally establish and second to describe quantitatively the effect of the size of metallic particles on the properties of the composite concerned, yet at the same filler concentration. This study was carried out on the model system ethylene-vinylacetate copolymer – nickel. The acquisition of experimental results required extensive measurements in a wide frequency and temperature interval, as well as a manufacture and preparation of a large set of samples with different concentrations and Ni filler sizes. Measurements were in part carried out at the Centre for Electronic Correlations and Magnetism, Institute of Experimental Physics V of the University of Augsburg (Germany) and, after the installation of a new cryogenic system, at the Department of Physics at FEEC, BUT Brno. Measurements were performed on a number of meters (Alpha-Analyzer of Novocontrol, HP4284A and HP4285A of Hewlett Packard and E4991A of Agilent) in the frequency range 1 Hz – 1 MHz and in the temperature interval 10 K – 300 K. The nickel concentration in systems studied varied from 0 % to 75 % and nickel particles were of a spherical shape with diameters between 35 and 115 m. The measurement results have shown that in the above frequency and temperature window just a single relaxation and a single conductivity mechanism occur. It was also proved that the frequency dependence of complex permittivity is for different Ni particle sizes at the same concentration different. These results have been quantified and a simple mathematical formula based on the Lichtenecker mixture rule has been proposed for their description. The physical origin of the effect of particle size at the same total nickel concentration is sought in different surface areas of internal interfaces between nickel and polymer in the composite