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Nowa metoda charakteryzacji dielektryków w paśmie częstotliwości subterahercowych

Godziszewski K., Yashchyshyn Y.

Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

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2018

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nr 6

501--504, CD

PL

W artykule przedstawiono nową metodę charakteryzacji materiałów dielektrycznych w paśmie subterahercowym. Opracowana metoda bazuje na szerokopasmowym pomiarze zespolonego współczynnika fali stojącej (ZWFS). Zaproponowany współczynnik ZWFS pozwala na określenie części rzeczywistej przenikalności elektrycznej i tangensa kąta stratności bez informacji o grubości próbki materiału poddawanego badaniom. Przeprowadzona analiza teoretyczna oraz wyniki badań eksperymentalnych potwierdzają słuszność przyjętej koncepcji pomiaru.

EN

A new method for characterization of dielectrics in the sub-terahertz frequency range is presented. This method makes it possible to characterize every dielectric by using only the measured complex reflection coefficient without accurate information about the thickness of dielectric sample. The mathematical model of the method is formulated. Finally, results of measurements for two different dielectrics are presented.

2

Enhanced Microwave Absorption of CNT Composites Mixing with Fe3O4 and Carbonyl Iron

Park J. H., Choi J., Lee K., Park J., Song J. K., Jeon E.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 3

1513--1516

EN

We fabricated two different kinds of composite materials for absorbing microwave in a frequency range of 2 to 18 GHz using coaxial airline and thru-reflect-line (TRL) method. The composite materials having carbon nanotube (CNT) with carbonyl iron (CI) or iron oxide (Fe3 O4 ) were fabricated by mixing each components. Magnetic properties were measured by SQUID equipment. Complex permittivity and complex permeability were also obtained by measuring S-parameters of the toroidal specimen dispersing CI/CNT and Fe3 O4 /CNT into the 50 weight percent (wt%) epoxy resin. The real permittivity was improved by mixing the CNT however, the real permeability was same as pure magnetic powders. The CI/CNT had a maximum value of real permittivity and real permeability, 11 and 1.4 at 10 GHz, respectively. The CNT composites can be adapted to the radar absorbing materials, band width 8-12 GHz.

3

Investigation of Metamaterial Structure Influence on Selective Properties of Microwave Waveguide Sensor

Isteníková K., Faktorová D.

Przegląd Elektrotechniczny

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2012

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R. 88, nr 7b

223-225

EN

The paper proposes the possibility of double negative metamaterial structure using for the transmission properties of open waveguide probe changing and the possibility of microwave open waveguide sensor tuning with metamaterial structure to be used for non-destructive testing of dielectric materials properties changing. The aim of our work was to develop a frequency selective sensor in microwave frequency band sensitive to changing of dielectric properties of investigated dielectric material.

PL

Opisano możliwość zastosowania struktury metamaterialnej posiadającej właściwości zmiany transmisji falowodu i możliwość srttrojenia czujnika falowodowego mikrofalowego. Czujnik można wykorzystać do badań nieniszczących materiałów dielektrycznych. Opracowano czujnik mikrofalowy o selektywnie zmienianej częstotliwości.

4

Modelling of electrical properties of composite dielectric systems

Serdyuk Y. V.

Prace Naukowe Instytutu Podstaw Elektrotechniki i Elektrotechnologii Politechniki Wrocławskiej. Konferencje

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2005

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Vol. 42, nr 16

64-76

EN

An approach for computer modelling of dielectric relaxation, effective dielectric properties and local characteristics (electric fields and power losses) of the composites is presented. Simulations are performed for binary mixtures with regular and stochastic structures using experimentally obtained frequency dependent properties of the constituent phases as input parameters. The model is verified by comparing the computed results with the experimental data. The developed procedure is then applied to analyze interfacial charges, fields and losses in a water-treed polymeric insulation of a high voltage cable.

5

Applicability of the FRA method for characterization of insulation of power transformers

Serdyuk Y. V., Podoltsev A. D., Gubański S. M.

Prace Naukowe Instytutu Podstaw Elektrotechniki i Elektrotechnologii Politechniki Wrocławskiej. Konferencje

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2004

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Vol. 40, nr 15

82-85

EN

Frequency response analysis (FRA) is usually used for diagnostics of mechanical deformations and displacements of transformer windings caused by electromagnetic forces during short circuits. In general, a high frequency response of a transformer is affected by the properties of all transformer components, and, thus, the FRA carries information about the state of the whole transformer including its main electrical insulation. From this point of view, the FRA might be considered as an alternative to the existing methods for assessment of the insulation. In the present paper, the applicability of the FRA is analysed using a high frequency model of a transformer, which takes into account the complex structure of the oil-paper insulation and frequency dependencies of the dielectric permittivities of the insulation components as well as winding resistances. A sensitivity analysis of the computed frequency responses to the variations in geometrical structure and complex permittivities of the components is presented.