Control of defects in the multilayer dielectric materials and coatings in the microwave range

2020 ◽  
Vol 86 (2) ◽  
pp. 37-43
Author(s):  
A. I. Kaz’min ◽  
P. A. Fedyunin
Keyword(s):  
Electromagnetic Wave ◽  
Frequency Dependence ◽  
Attenuation Coefficient ◽  
Electromagnetic Waves ◽  
Dielectric Materials ◽  
Geometric Parameters ◽  
Microwave Range ◽  
Surface Electromagnetic Wave ◽  
Phase Measurements ◽  
Multilayer Dielectric

The development of modern engineering is inextricably linked with the development of the new types of multilayer dielectric materials. Existing radio wave methods for monitoring interlayer defects in such materials exhibit low accuracy in reconstructing the geometric parameters of defects. The results of studying extended interlayer defects in the three-layer coating consisting of polymethyl methacrylate, F-4D PTFE, and semi-hard rubber by the method of surface electromagnetic waves are presented. The method is based on the solution of inverse problems in the reconstruction of the geometric parameters of extended interlayer defects of special multilayer materials and coatings from the frequency dependence of the attenuation coefficient of the field of a slow surface electromagnetic wave. Unlike the methods that make use from the complex reflection coefficient we proposed to increase the accuracy of the reconstruction of the geometric parameters of extended interlayer defects taking into account the linear frequency dependence of the attenuation coefficient as well as reducing the number of fixed measurement frequencies. Moreover, the determination procedure is rather simple, since only the field strength of the surface electromagnetic wave is measured, and there is no need for phase measurements. Experimental data obtained on a multifrequency measuring complex in the range of 10 – 11 GHz were used for reconstruction of the interlayer defects in the coating under study. The developed method provided a relative error of thickness estimation below 10%. The proposed method approach can be used in studying multilayer dielectric coatings on the metal for detection of delamination in the lack of glue or poor adhesion between the layers. The developed method is also suitable for control of the defects in semiconductors, ferrite and composite materials.

Evaluation of the accuracy of reconstruction of the electrophysical and geometric parameters of multilayer dielectric coatings by the multi-frequency radio wave method of a slow surface electromagnetic waves

2020 ◽  
pp. 51-58
Author(s):  
Aleksandr I. Kazmin ◽  
Pavel A. Fedjunin
Keyword(s):  
Radio Wave ◽  
Noise Level ◽  
Electromagnetic Waves ◽  
Dielectric Materials ◽  
Geometric Parameters ◽  
Experimental Investigations ◽  
Wave Method ◽  
Dielectric Coatings ◽  
Surface Electromagnetic Waves ◽  
Multilayer Dielectric

One of the most important diagnostic problems multilayer dielectric materials and coatings is the development of methods for quantitative interpretation of the checkout results their electrophysical and geometric parameters. The results of a study of the potential informativeness of the multi-frequency radio wave method of surface electromagnetic waves during reconstruction of the electrophysical and geometric parameters of multilayer dielectric coatings are presented. The simulation model is presented that makes it possible to evaluate of the accuracy of reconstruction of the electrophysical and geometric parameters of multilayer dielectric coatings. The model takes into account the values of the electrophysical and geometric parameters of the coating, the noise level in the measurement data and the measurement bandwidth. The results of simulation and experimental investigations of reconstruction of the structure of relative permittivitties and thicknesses of single-layer and double-layer dielectric coatings with different thicknesses, with different values of the standard deviation (RMS) of the noise level in the measured attenuation coefficients of the surface slow electromagnetic wave are presented. Coatings based on the following materials were investigated: polymethyl methacrylate, F-4D PTFE, RO3010. The accuracy of reconstruction of the electrophysical parameters of the layers decreases with an increase in the number of evaluated parameters and an increase in the noise level. The accuracy of the estimates of the electrophysical parameters of the layers also decreases with a decrease in their relative permittivity and thickness. The results of experimental studies confirm the adequacy of the developed simulation model. The presented model allows for a specific measuring complex that implements the multi-frequency radio wave method of surface electromagnetic waves, to quantify the potential possibilities for the accuracy of reconstruction of the electrophysical and geometric parameters of multilayer dielectric materials and coatings. Experimental investigations and simulation results of a multilayer dielectric coating demonstrated the theoretical capabilities gained relative error permittivity and thickness of the individual layers with relative error not greater than 10 %, with a measurement bandwidth of 1 GHz and RMS of noise level 0,003–0,004.

Multifrequency optimization method of measurement the frequency dependency of electrophysical parameters of dielectric and magnetodielectric coatings

2021 ◽  
pp. 54-61
Author(s):  
Aleksandr I. Kaz'min
Keyword(s):  
Frequency Dependence ◽  
Radio Wave ◽  
Optimization Method ◽  
Metal Substrate ◽  
Geometric Parameters ◽  
Microwave Range ◽  
Electrodynamic Modeling ◽  
Wave Methods ◽  
Electrophysical Parameters

The issues of experimental determination of electrodynamic parameters of existing and new synthesized materials and coatings used in the microwave range are highlighted. Problems arising from measurements of the electrophysical and geometric parameters of dielectric and magnetodielectric coatings, taking into account their placement on a metal substrate, by radio wave methods are considered. We present the new radio wave method of joint measurements of the frequency dependence of the complex permittivity, the frequency dependence of the complex magnetic permeability, and the thickness of plane-layered samples of dielectric and magnetodielectric coatings on a metal substrate. Determination of electrophysical and geometric parameters of the coating in the proposed method is reduced to minimizing the objective function constructed based on the discrepancy between the experimental and design theoretical values of the attenuation coefficients of surface electromagnetic wave fields on a grid of discrete frequencies. The simulation model of measurements is shown, implemented on the basis of the electrodynamic modeling system CST Microwave studio (Simulia corporation, USA) and the Matlab system. The results of simulation are presented to determine the frequency dependences of the electrophysical parameters and the thickness of a sample of a radio-absorbing coating on a metal substrate. Errors in the estimates of permittivity and permeability in the measurement frequency band 9–13.5 GHz, which are no more than 10 % with a confidence level of 0.95 with a mean square deviation of the noise level of 0.006, have been obtained. The proposed method can be in demand in various science-intensive areas – microelectronic, aerospace, mechanical engineering, etc.

scholarly journals Векторный потенциал электромагнитной волны над сильноиндуктивной двуслойной земной поверхностью

2019 ◽  
Vol 89 (9) ◽  
pp. 1439
Author(s):  
В.К. Балханов ◽  
Ю.Б. Башкуев ◽  
Л.Х. Ангархаева
Keyword(s):  
Electromagnetic Wave ◽  
Vector Potential ◽  
Electromagnetic Waves ◽  
Phase Speed ◽  
Singular Points ◽  
Effective Parameters ◽  
Surface Electromagnetic Wave ◽  
Light Speed ◽  
Sommerfeld Integral ◽  
Surface Electromagnetic Waves

The vertical components of the vector potential of an electromagnetic wave for a two-layer strongly inductive impedance medium are determined. The solution is presented as the Sommerfeld integral. The singular points of this integral were determined using the effective parameters. The question of the phase speed of a surface electromagnetic wave is considered. It is shown that it is always less than the light speed in a vacuum. This means that surface electromagnetic waves are not Zenneck waves, whose phase speed is greater than the light speed, like electromagnetic waves in waveguides.

scholarly journals Quality control of substances by electromagnetic sensing in a waveguide

2020 ◽  
Keyword(s):  
Dielectric Constant ◽  
Electromagnetic Wave ◽  
Standing Wave ◽  
Dielectric Materials ◽  
Complex Dielectric Constant ◽  
Microwave Range ◽  
Dielectric Sample ◽  
Layered Dielectric ◽  
Dielectric Structures ◽  
Non Destructive

Relevance. The problems of remote non-destructive determination and control of quality indicators of a wide variety of material environments, in particular, household and food products, are relevant practically for all areas of the national economy, science and technology. The relevance of scientific research in the field of dielectrometry in the microwave range is also due to the needs for the development of high technologies in medicine and health care, the national economy in real time. The aim of this work is to develop the method of microwave waveguide dielectrometry based on the application of the theory of multilayer plane-layered dielectric structures to the determination of the complex dielectric constant of a substance from the values ​​of the standing wave ratio of the samples under study in a waveguide at two close frequencies. Materials and methods. The research is based on well-studied phenomena of interference of electromagnetic waves on multilayer plane-layered dielectric structures. By using a mathematical model of the phenomenon of interference of a plane electromagnetic wave on a three-layer dielectric structure, the ambiguity of determining the complex dielectric constant of a substance by the classical method of waveguide dielectrometry in the microwave range by measuring the standing wave ratio of a dielectric sample placed in the waveguide and the phase angle of the reflection coefficient is overcome. Results. A method is proposed for ensuring the unambiguity of determining the complex dielectric constant of a substance in waveguide dielectrometry on the basis of the theory of multilayer plane-layered dielectric structures. The method leads to an explicit expression for the complex reflection coefficient of an electromagnetic wave from the investigated dielectric sample placed in a rectangular waveguide. The complex dielectric constant of a substance is determined from the values ​​of the standing wave ratio at two close frequencies in the microwave range. By the found value of the dielectric constant and the tangent of the dielectric loss angle, the quality parameter of the substance is determined by comparing and optimizing two objective functions, including the arrays of reference values ​​of the complex dielectric constant obtained in the course of measurements and compiled in advance, and by comparing and optimizing the third objective function, previous functions. As an example of an indicator of the quality of a substance, the specific heat of combustion of coal was determined. Conclusions. The proposed method for determining the complex dielectric constant and quality indicators of dielectric materials in the microwave frequency range has been tested in the case of various types of coals, its efficiency has been proven and the reliability of the results has been proven. The method and the devices and software implemented on its basis are promising for non-destructive express control of dielectric materials and media.

scholarly journals To the Question of the Independence of the Surface Electromagnetic Wave Frequency

2019 ◽  
Vol 1 (1) ◽  
Author(s):  
V. K. Balkhanov ◽  
Yu B. Bashkuev
Keyword(s):  
Electromagnetic Wave ◽  
Layer Thickness ◽  
Dielectric Layer ◽  
Free Space ◽  
Electromagnetic Waves ◽  
Wave Frequency ◽  
Waveguide Channel ◽  
Surface Electromagnetic Wave ◽  
Minimum Frequency ◽  
Waveguide Theory

Earth's the surface is often strongly inductive, consisting of a dielectric layer thickness endpoint, lying on an unlimited conductor basis. Electromagnetic wave, spreading along the surface, it appears captured dielectric layer, spreading it as in the waveguide channel. Waveguide theory it is known that the spread in the waveguide can only electromagnetic waves with a discrete set of frequencies. And experience shows that the captured waveguide channel electromagnetic waves can be any frequency. The article found that this behavior is due to the fact that electromagnetic waves in free space border - dielectric layer damped height in several wavelengths. Thus the thickness of the dielectric layer becomes more effectively, and this leads to a reduction of the minimum frequency of the waveguide. A discrete set of frequencies is blurred so that cover each other. Thus, a discrete set of frequencies becomes solid, and captured waveguide channel electromagnetic waves are independent of frequency.

Detection of delamination in composites by using electromagnetic penetrating radar

2014 ◽  
Vol 5 (2) ◽  
pp. 151-156
Author(s):  
Z. Mechbal ◽  
A. Khamlichi
Keyword(s):  
Electromagnetic Wave ◽  
Electromagnetic Waves ◽  
Electromagnetic Wave Propagation ◽  
Wave Reflection ◽  
Image Features ◽  
Partial Reflection ◽  
Straight Path ◽  
Reflected Signal ◽  
Short Time ◽  
Intervening Factors

Composites made from E-glass/epoxy or aramid/epoxy are frequently used in aircraft and aerospace industries. These materials are prone to suffer from the presence of delamination, which can reduce severely the performance of aircrafts and even threaten their safety. Since electric conductivity of these composites is rather small, they can propagate electromagnetic waves. Detection of delamination damage can then be monitored by using an electromagnetic penetrating radar scanner, which consists of emitting waves having the form of short time pulses that are centered on a given work frequency. While propagating, these waves undergo partial reflection when running into an obstacle or a material discontinuity. Habitually, the radar is moved at constant speed along a straight path and the reflected signal is processed as a radargram that gives the reflected energy as function of the two-way time and the antenna position.In this work, modeling of electromagnetic wave propagation in composites made from E-glass/epoxy was performed analytically. The electromagnetic wave reflection from a delamination defect was analyzed as function of key intervening factors which include the defect extent and depth, as well as the work frequency. Various simulations were performed and the obtained results have enabled to correlate the reflection pattern image features to the actual delamination defect characteristics which can provide quantification of delamination.

New Approach to the Theory of Circular Dichroism

1998 ◽  
Vol 63 (8) ◽  
pp. 1187-1201 ◽  
Author(s):  
Jaroslav Zamastil ◽  
Lubomír Skála ◽  
Petr Pančoška ◽  
Oldřich Bílek
Keyword(s):  
Electromagnetic Wave ◽  
Circular Dichroism ◽  
Electromagnetic Waves ◽  
Maxwell Equations ◽  
Optically Active ◽  
Semiclassical Approach ◽  
New Approach ◽  
Isotropic Media ◽  
New Formula ◽  
Circular Dichroïsm

Using the semiclassical approach for the description of the propagation of the electromagnetic waves in optically active isotropic media we derive a new formula for the circular dichroism parameter. The theory is based on the idea of the time damped electromagnetic wave interacting with the molecules of the sample. In this theory, the Lambert-Beer law need not be taken as an empirical law, however, it follows naturally from the requirement that the electromagnetic wave obeys the Maxwell equations.

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