Academic literature on the topic 'Effective tangent of dielectric losses angle'

The purpose of the paper is to study the dependence of dielectric losses of mechanically activated grain crops on example of wheat under heat treatment on temperature and external electric field frequency as well as to examine the effect of particle size of fine grain samples on grain electrophysical characteristics and dielectric losses. Experimental samples of dispersed systems with particle sizes in the range from 50 to 1000 μm are prepared by the method of mechanical activation. The temperature dependence of the dielectric loss angle tangent is measured using the dielectric method over a wide frequency range. The dependence of the dielectric loss angle tangent tgδ of mechanically activated wheat samples with the different degrees of particle dispersion in a wide temperature range from 20°C to 250°C with a heating rate of 0.7 deg/min is studied. It is found out that the external electric field frequency varies in the range from 25 Hz to 106 Hz. Electric capacitance and conductivity are measured using an E7-20 immitance meter and a specially designed measuring cell. Dielectric characteristics are calculated. Experimental data are presented in the form of graphs and diagrams. We have determined the correlation of the tangent of the dielectric loss angle tgδ with the frequency of the external electric field and temperature, which is most characteristic for fine samples. The most finely dispersed samples with a particle size of less than 50 microns are shown to have high electrical activity. Increase in the dielectric permittivity and the tangent of the dielectric loss angle is most noticeable at the frequencies below 100 Hz. The study of dielectric characteristics allows to choose an effective energy-saving drying mode of the crop under study.

Introduction. The presence of semiconductor shields leads to additional dielectric losses compared to polymer insulation without shields. Losses in cables in the presence of semiconductor coatings depend on the dielectric permittivity and resistivity of the composite polymeric material, which are frequency-dependent characteristics. Purpose. To determine in a wide range of frequencies, taking into account the variance of electrophysical characteristics and thickness of semiconductor shields effective electric capacitance and tangent of dielectric losses angle of high-voltage power cables with polymer insulation. Methodology. Serial-parallel nonlinear circuit replacement of semiconductor coatings and linear polymer insulation to determine in a wide range of frequency the effective parameters of the dielectric absorption of a three-layer composite system of high-voltage power cables of single core. Practical value. The obtained relations are the basis for the development of practical recommendations for substantiating the thickness and electrophysical parameters of semiconductor shields to reduce the impact on the effective tangent of the dielectric losses angle of a three-layer composite system of high-voltage power cables.

<strong><em>Introduction</em></strong><em>. The presence of semiconductor shields leads to additional dielectric losses compared to polymer insulation without shields. Losses in cables in the presence of semiconductor coatings depend on the dielectric permittivity and resistivity of the composite polymeric material, which are frequency-dependent characteristics.&nbsp;<strong>Purpose.</strong>&nbsp;To determine in a wide range of frequencies, taking into account the variance of electrophysical characteristics and thickness of semiconductor shields effective electric capacitance and tangent of dielectric losses angle of high-voltage power cables with polymer insulation.&nbsp;<strong>Methodology.&nbsp;</strong>Serial-parallel nonlinear circuit replacement of semiconductor coatings and linear polymer insulation to determine in a wide range of frequency the effective parameters of the dielectric absorption of a three-layer composite system of high-voltage power cables of single core.&nbsp;<strong>Practical value.</strong>&nbsp;The obtained relations are the basis for the development of practical recommendations for substantiating the thickness and electrophysical parameters of semiconductor shields to reduce the impact on the effective tangent of the dielectric losses angle of a three-layer composite system of high-voltage power cables.</em>

Dependences of complex dielectric permitivity and tangent of dielectric losses angle are explored in the range of temperatures T = 280 - 360 К at the frequencies of 10 GHz and 30 GHz at different concentrations of dispersion phase of carbon in polymeric composite material. It is shown that polymeric composites possesses the least values of temperature coefficient of tangent of dielectric losses angle (nearly 10~5 К 1) with maintenance of carbon more than 20%

The article provides an overview of the physical foundations and features of the application of diagnostic methods for the insulation of power cables using dielectric spectroscopy methods in the frequency and time domains. The relationship between the depolarization currents and the frequency spectrum of the complex dielectric constant is shown. An analysis of the factors determining the frequency dependence of the tangent angle of dielectric losses of paper and polyethylene insulation of power cables is given. The main types of reaction of dielectric materials with different levels of development of water channels at the level and frequency of the applied voltage are listed. According to the results of the analysis, it is shown that for high-voltage measurements, one of the factors that complicates the diagnosis of the insulation of power cables by analyzing the frequency dependences of the capacitance and the tangent of the dielectric loss angle is the distortion of the sinusoidal current through the dielectric due to the nonlinear dependence of the complex dielectric constant on the level of the applied voltage. A comparative analysis of dielectric spectroscopy methods in the frequency domain, involving high-voltage and low-voltage measurements of the complex dielectric constant, was carried out. The correlation between the tangent of the dielectric loss angle of paper insulation and its mechanical characteristics is shown

The frequency and temperature dependences of the tangent of dielectric loss angle as well as the real and imaginary part of the dielectric constant of MnGaInTe4 crystals are investigated in the frequency range of 102 to 106 Hz. The experimental values of the studied characteristics are determined. The real and imaginary parts of the permittivity are found to undergo significant dispersion, which has a relaxation nature. The main type of dielectric losses in MnGaInTe4 crystals in the frequency range of 102 to 106 Hz are the electrical conductivity losses. The conductivity is characterized by a zone-hopping mechanism. The activation energies of charge carriers are determined.

Introduction. Over the past 10 years, the number of industrial networks has more than doubled. At the physical level, all industrial technology networks are based on twisted pair. Purpose. Synthesis of constructive-technological decisions of regulation of electric capacitance of the insulated conductor at a stage of manufacturing of twisted pair of cables of industrial networks. Methodology. The method of secondary charges to determine the capacitance of the insulated conductor by varying the thickness of the solid and foamed polyethylene insulation. Practical value. Effective regulation is provided on the basis of the obtained dependencies of the effective dielectric constant, the tangent of the dielectric loss angle and the capacitance of the insulated conductor on the degree of foaming and the thickness of the protective film of two-layer insulation. At a degree of porosity of 40 %, the dielectric constant decreases by 25 %, the tangent of the dielectric loss angle – by 33 %, the electrical capacitance of the insulated conductor – by 20 %.

Modern marine vessels use electrically driven rudders; cruise liners, gas carriers, tankers are equipped with Azipod systems manufactured by the Swedish-Swiss company ABB. Gondola-type propellers make it possible to break ice when the vessel is moving astern, therefore such vessels are used for work on the Northern Sea Route, in particular, when working on the Yamal LNG project. The 22MW Azipod propulsion system rotates 360° and enables difficult maneuvering without the assistance of tugs. When operating such propellers, powerful diesel generators are installed on the ship. For the transmission of electricity, ship cables are used, which are subject to increased requirements that meet the standard of the International Electrotechnical Commission. Modern marine vessels are equipped with XLPE or EPDM insulated cable lines; industrial production of these cables is carried out in the Russian Federation. In the course of the study, a method for auditing the state of insulation has been considered based on an assessment of the change in the tangent of the angle of dielectric losses in the process of thermal aging of the cable of the PvBPng(A)-HF brand. Measurements of the tangent of the dielectric losses' angle have been carried out with a Tangens-2000 insulation parameter meter.

<strong><em>Introduction.</em></strong><em>&nbsp;Over the past 10 years, the number of industrial networks has more than doubled. At the physical level, all industrial technology networks are based on twisted pair.&nbsp;<strong>Purpose.</strong>&nbsp;Synthesis of constructive-technological decisions of regulation of electric capacitance of the insulated conductor at a stage of manufacturing of twisted pair of cables of industrial networks.&nbsp;<strong>Methodology.</strong>&nbsp;The method of secondary charges to determine the capacitance of the insulated conductor by varying the thickness of the solid and foamed polyethylene insulation.&nbsp;<strong>Practical value.</strong>&nbsp;Effective regulation is provided on the basis of the obtained dependencies of the effective dielectric constant, the tangent of the dielectric loss angle and the capacitance of the insulated conductor on the degree of foaming and the thickness of the protective film of two-layer insulation. At a degree of porosity of 40 %, the dielectric constant decreases by 25 %, the tangent of the dielectric loss angle &ndash; by 33 %, the electrical capacitance of the insulated conductor &ndash; by 20 %.</em>

The problem of studying the interaction of laser radiation with polymer materials lies in the study of the effect of intense energy fluxes on matter. The effect of pulsed laser radiation on a high-molecular substance was studied from changes in the electrical parameters of the irradiated materials. Changes in ε’, tg δ depending on the frequency of the external field, the dose of laser irradiation, temperature and time were investigated by a highly sensitive physicochemical method -the method of dielectric losses. This article examined the impact of laser radiation on the dielectric properties of polymethylmethacrylate at frequency of 50 kHz within the temperature interval from 170 to 420 K. The authors showed that the processing of the samples with laser radiation leads to substantial changes in the dielectric constant and tangent of dielectric loss angle.

Актуальність теми Застосування діелектричних резонаторів в електроніці НВЧ сприяє створенню високоефективних резонансних пристроїв. Вдосконалення характеристик цих систем є актуальною задачею. Зв'язок роботи з науковими програмами, планами, темами. Робота пов’язана з науковими програмами, планами та темами що розроблюються на кафедрі. Мета і задачі дослідження. Метою даної робити є вдосконалення пристроїв НВЧ на основі тонких діелектричних резонаторів. Для досягнення мети, необхідно виконати наступні задачі: 1. Проаналізувати існуючі структури НВЧ. 2. Дослідити структури НВЧ на основі тонких діелектричних резонаторів. 3. Показати перспективність конструювання пристроїхв НВЧ на основі тонких діелектричних резонаторів. Об’єктом дослідження є структури НВЧ на основі тонких діелектричних резонаторів. Предметом дослідження є електродинамічні властивості і характеристики тонких діелектричних резонаторів. Методика наукового дослідження включає: методи аналізу НВЧ-пристроїв, аналітичне моделювання. Практичне значення одержаних результатів. Запропоновано конструкції керованого фазообертача на основі тонких діелектричних резонаторів, що дозволило знизити керуючу напругу. Особистий внесок здобувача: • Експериментально досліджено електродинамічні характеристики фазообертачів на основі тонких діелектричних резонаторів. • Запропоновано конструкції фазообертачів із зниженою керуючою напругою. Структура і об'єм роботи. Робота складається зі вступу, шістьох розділів, висновків та списку використаних джерел. Загальний обсяг дисертації становить 76 сторінки. Робота включає 16 рисунків, 29 таблиць, список використаних джерел з 26 найменувань.<br>Actuality of theme The use of dielectric resonators in microwave electronics helps to create highly effective resonance devices. Improving the characteristics of these systems is an urgent task. Relationship of work with scientific programs, plans, themes. The work is connected with the scientific programs, plans and themes that are being developed at the department. The purpose and tasks of the study. The purpose of this work is to improve the microwave devices based on thin dielectric resonators. To achieve the goal, you need to accomplish the following tasks: 1. Analyze existing microwave structures. 2. To study the microwave structure on the basis of thin dielectric resonators. 3. Show the prospect of designing devices on microwave based on thin dielectric resonators. The object of the study is the structure of microwave based on thin dielectric resonators. The subject of the study is electrodynamic properties and characteristics of thin dielectric resonators. The method of scientific research includes: methods of analysis of microwave devices, analytical modeling. The practical value of the results. The designs of a controlled phase rotator on the basis of thin dielectric resonators were proposed, which allowed to reduce the control voltage. The applicant's personal contribution: • Electrodynamic characteristics of phase rotators on the basis of thin dielectric resonators have been experimentally investigated. • The designs of phase rotators with reduced control voltage are proposed. Structure and volume of work. The work consists of an introduction, six sections, conclusions and a list of sources used. The total volume of the dissertation is 76 pages. The work includes 16 drawings, 29 tables, list of used sources from 26 titles.

Low Temperature Co-fired Ceramic (LTCC) materials are widely used in ceramic packaging and interconnect applications, such as RF receiving modules for next generation handsets and T/R modules for satellite communications. The application frequency spans from low GHz to 100+ GHz. A variety of techniques must be used to characterize dielectric properties (loss tangent and dielectric constant) of LTCC in the wide frequency range. These techniques include the parallel plate capacitor method from DC to several MHz, cavity methods in x-band, and open resonator techniques for frequencies up to 100+ GHz. LTCC is a multi-layer ceramic technology, which offers capability for low cost manufacturing, realizing 3D structures, and embedding passive components. Both strip line and microstrip types of transmission line structures can be conveniently manufactured using LTCC material systems. As an important performance parameter, microstrip loss can be characterized using the ring resonator technique. Both LTCC and metal conductors contribute to the microstrip loss. At microwave and mm-wave frequencies, metal losses become significant, although low resistance silver conductor can be used. The metal loss may be divided into two categories: one is the resistive loss and other is surface roughness loss. A photo imaging technique has been introduced which patterns the microstrip, reducing the surface loss. In this paper, the techniques for measuring both dielectric properties of A6 LTCC and microstrip properties of A6 LTCC with conductor systems will be reviewed. Characterization results of the dielectric constant and loss tangent of A6 from near DC to 100 GHz will be presented. Microstrip losses, measured for A6 LTCC with both gold and silver metallization up to 40 GHz, are compared to those computed using the closed form equations and experimentally determined dielectric and conductor properties. The calculated effective microstrip permitivity and attenuation compare well to those from measurements.

EXPERIMENTAL STUDY OF MICROWAVE SLOW WAVE COMB AND CERAMIC APPLICATORS FOR SOIL TREATMENT AT FREQUENCY 2.45 GHZ. G. Brodie and G. Torgovnikov University of Melbourne, 4 Water St, Creswick, Victoria 3363, Australia; e-mail: grigori@unimelb.edu.au Keywords: ceramic applicator, comb applicator, microwave, slow wave, soil microwave treatment In many cases in industry it is required to heat or treat surface layers of different material (soil, timber, concrete, plastics and so on) with microwaves (MW). Traditional MW irradiators (antennas) cannot provide heating only in the surface areas and energy penetrates deep into the material, where it decays exponentially due to normal attenuation. Therefore, energy losses, if a heating depth of 20 - 40 mm (for example to heat soil for killing weed seeds) is all that is required, are very significant. Therefore, it is required to develop special MW applicators for surface treatment to increase process efficiency. To address this problem, a slow wave (which is sometimes called a "surface wave" applicator) comb and ceramic structures, was studied. The main property of slow waves is that the energy concentration is very near impedance electrode – comb or ceramic plate surface. Previously, slow wave structures were used mostly as delay lines and as interaction circuits in MW vacuum devices, and their properties were explored only for these specific applications. The work objectives of this study were: design slow wave, ceramic and comb structure applicators for soil treatment at frequency 2.45 GHz;experimentally study the energy distribution from slow wave applicators in the soil;study of opportunities to use slow wave structures for surface soil layer heating; andrecommendations for practical use of new slow wave applicators. Comb and ceramic slab applicators for frequency 2.45 GHz operation were designed for the soil treatment on the bases of theoretical studies and computer modelling. The comb applicator was made from aluminium and the ceramic slab applicator was made from alumina (DC=9.8, loss tangent=0.0002). A 30 kW (2.45 GHz) microwave generator was used for experiments. Containers with soil were placed on the applicator surface. An auto tuner was used in MW system to provided good impedance matching of the generator and applicators (with soil on top). This resulted in practically no power reflection. The soil “Potting Mix Hortico”, with moisture content range 32-174% and density range 590-1070 kg/m3, was used for the experiments. Energy distribution in the soil was determined by temperature measuring in the soil using thermocouples, after MW heating. Distribution of temperature measuring points covered the whole volume of the soil along and across the applicator. Results of the experiments showed that the comb applicator provides maximum energy release in soil in the central vertical plane. The ceramic alumina applicator forms two temperature maximums in two vertical planes at a distance of about 40 mm from the central applicator plane and a minimum in the applicator central plane. The ceramic applicator provides better uniformity of energy distribution across the width of the applicator due to the two temperature maximums. It reduces overheating of the soil surface and energy losses. The depth of energy penetration provided by ceramic applicator is lower compared with the comb applicator. It means that the ceramic applicator provides better energy localization and more energy absorption in the soil surface layers compared with the comb applicator. To provide better uniformity of energy distribution across the ceramic applicator it is recommended to use ceramics with higher dielectric constants, such as in the range of 15-25, which will allow more energy to be released closer to the applicator surface. It will increase efficiency of MW energy use. The ceramic applicator is more effective for MW treatment of the soil surface areas and is recommended for practical use in machines for thermal treatment and sterilization of surface layers of the soil and other materials.