Reflection Of Electromagnetic Radiation Research Articles

Electromagnetic radiation reflection, transmission and absorption characteristics of charcoal-containing materials impregnated with chlorides aqueous solutions

The experimentally established regularities of changes in electromagnetic radiation reflection, transmission and absorption characteristics in the frequency range of 2.0–17.0 GHz of materials are presented. These materials contained powdered activated birch charcoal impregnated with chlorides aqueous solutions (calcium chloride, magnesium chloride and sodium chloride). Using the established regularities, it was determined that materials based on powdered activated birch charcoal impregnated with calcium chloride aqueous solution are radioabsorbing if they interact with electromagnetic radiation in the frequency ranges of 3.5–4.5 and 5.5–17.0 GHz. In turn, materials based on powdered activated birch charcoal impregnated with magnesium and sodium chlorides aqueous solutions are radioabsorbing if they interact with electromagnetic radiation in the frequency ranges of 2.0–17.0 and 2.0–7.5 GHz (magnesium chloride solution), 10.0–17.0 GHz (sodium chloride solution). Electromagnetic radiation absorption coefficient values of the studied materials reach 0.95. These materials seem promising for the manufacture of partitions to shield sectors of premises where electronic devices sensitive to electromagnetic interference are located.

Momentary analysis of the electromagnetic radiation of gabbro rock under compressive stress

The phenomenon of electromagnetic radiation resulting from the application of pressure to rocks is caused by physical and chemical processes. Applying uniaxial pressure on gabbro rocks breaks the peroxy bonds and produces electron-hole pairs. These holes flow in the volume of gabbro rock under pressure and cause changes in electric charge, and as a result, generate variable electric and magnetic fields that vary with time and create electromagnetic signal. In this research work, by measuring the electric current of gabbro rock under pressure, its Fourier function is extracted, and the equations of the electric and magnetic fields of the sample and the energy and radiation equations of electromagnetic waves are calculated. Also, the relationship between these equations and the electric current equation is expressed. In addition, the amounts of absorption, transmission, and reflection of electromagnetic radiation of the rock can be analyzed during the application of pressure using the diagram of the radiant power of electromagnetic signal. The study of electromagnetic radiation can be useful for the development of electromagnetic radiation technology, can provide early warning about the risk of rock falls, and can reduce human injuries caused by the fall of places such as mines and tunnels.

Charcoal-containing microwave electromagnetic radiation absorbers with relief surface

A new technology for manufacturing microwave electromagnetic radiation (EMR) absorbers characterized by a geometrically inhomogeneous surface is presented. The novelty of the presented technology lies in the use of radiotransparent polymer forms with hemispherical depressions of the same volume, which are the component for the formation of the surface layer of absorbers. The technology consists in filling these molds with a mixture of powdered activated (birch) charcoal and the binder in the liquid phase and further drying it in the forms. Compared with analogues, the developed technology is characterized by low complexity of reproduction. Most of the time required to implement the presented technology is associated with the drying process of a mixture of powdered activated birch charcoal and a binder. The experimentally established patterns of changes in the values of electromagnetic radiation reflection and absorption coefficients in the frequency range 1.0–28.0 GHz of the absorbers manufactured in accordance with the presented technology are provided, depending on the type of binder contained in them (polyvinyl acetate aqueous solution, gypsum aqueous solution, polyurethane mastic). It was determined that the most effective of the EMR absorbers studied in the course of establishing the indicated patterns are those ones that contain an aqueous solution of polyvinyl acetate. Electromagnetic radiation absorption coefficient values in the frequency range 1.0–28.0 GHz of such absorbers vary from 0.75 to 0.99. In addition, the mass per unit area of such absorbers is 1.5–2.0 times less than the mass per unit area of absorbers containing an gypsum aqueous solution or polyurethane mastic. Microwave EMR absorbers manufactured using the presented technology are characterized by higher mechanical strength, as well as lower cost compared to analogues and are recommended for use in the creation of anechoic chambers.

MICROWAVE ABSORBERS BASED ON MÖBIUS STRIP RESONATORS

The paper deals with technology of manufacturing of microwave absorbers with ordered and structured surface layer. This layer contains Möbius strip resonators, located on the fixed distance from each other. The technology was developed by the authors on the base of the following data: 1) results of theoretical study of microwaves interaction with Möbius strip resonator; 2) results of experimental study of electromagnetic radiation reflection, transmission and absorption coefficients in the microwave frequency range of the experimental samples of microwave absorbers based on Möbius strip resonators, which differ by the distance between these resonators. It was established on the base to the listed results that the microwave absorbers manufactured in accordance to the technology proposed by the authors are wide-band ones. Electromagnetic radiation absorption coefficient values of these absorbers changes from 0.5 to 0.97 in frequency range 2.0–17.0 GHz if the distance between the Möbius strip resonators containing in their surface layer, is 15.0 mm. If the distance between the Möbius strip resonators containing in the surface layer of the considered absorbers is less than 15.0 mm their electromagnetic radiation absorption coefficient in the indicated frequency bands is lower than presented values. The considered absorbers are promising for use in shielded rooms and anechoic chambers.

Reflection of the Electromagnetic Wave from the Region of Electron Cyclotron Absorption in Thermonuclear Plasma

A new approach to the problem of the passage of the extraordinary wave through the region of the electron–cyclotron resonance in inhomogeneous plasma was considered in the framework of the full set of Maxwell’s equations, taking into account the effects of spatial dispersion and resonance dissipation. For the model one-dimensional geometry, field distributions were calculated in the vicinity of the cyclotron resonance at the second harmonic for the normal incidence of the extraordinary wave and the reflection, transmission, and absorption coefficients were found depending on the parameters of the resonance region. As a result, the fine effect of the reflection of electromagnetic radiation from the cyclotron resonance region in transparent plasma was described and the results were compared with the observations of this effect in the experiments on the microwave heating of the plasma at the L-2M stellarator.

Reflection of the Electromagnetic Wave from the Region of Electron Cyclotron Absorption in Thermonuclear Plasma

A new approach to the problem of the passage of the extraordinary wave through the region of the electron–cyclotron resonance in inhomogeneous plasma was considered in the framework of the full set of Maxwell’s equations, taking into account the effects of spatial dispersion and resonance dissipation. For the model one-dimensional geometry, field distributions were calculated in the vicinity of the cyclotron resonance at the second harmonic for the normal incidence of the extraordinary wave and the reflection, transmission, and absorption coefficients were found depending on the parameters of the resonance region. As a result, the fine effect of the reflection of electromagnetic radiation from the cyclotron resonance region in transparent plasma was described and the results were compared with the observations of this effect in the experiments on the microwave heating of the plasma at the L-2M stellarator.

Promising Smart Materials for Radioelectronics

The investigations of a multilayer material – a polymeric radio-transparent electrically conductive film of polyaniline with a concentration of 5, 10 and 50 % by weight on a radio-transparent fiberglass substrate were carried out. Such materials are multifunctional – the material itself has the required characteristics, but when it is exposed to external electromagnetic radiation, it provides shielding functions. Electrically conductive polymer samples (polyaniline film) deposited on a fiberglass substrate have low attenuation in the 8–12 GHz transparency band, low electromagnetic radiation reflection coefficient, high conductivity and performance characteristics, as well as manufacturability.

The Technique for Manufacturing Flexible Electromagnetic Shields Based on Resistive Materials

The article introduces the technique for manufacturing flexible electromagnetic shields based on resistive materials ( powdered charcoals and sheet foil ), as well as the results of experimental justification of the use prospects of this technique in the development of new functional materials . This justification consisted of : 1) manufacturing of the experimental samples in accordance with the presented technique ; 2) carrying out the measurements of the electromagnetic radiation reflection and transmission coefficient values in the frequency range of 0.7–17.0 GHz of the manufactured experimental samples . It was discovered that flexible electromagnetic shields based on the powdered charcoals manufactured in accordance with the presented technique are characterized by the electromagnetic radiation reflection coefficient values in the frequency range of 0.7–17.0 GHz , reaching –10.0 dB , when electromagnetic radiation reflection coefficient values reach –20.0 dB . Due to this fact it is possible to r ecommend to use them in order to ensure electromagnetic compatibility of radioelectronic equipment and to protect people from exposure to radiation , emitted by such equipment , as well as to hide ground objects from detection in the radar wavelength range .

Heterogeneous radio absorbing composite materials based on powdered charcoals for electronic devices protection from the electromagnetic radiation impact

The results of theoretical and experimental substantiation of the technique developed by the authors for the manufacture of heterogeneous (two- or three-layer) radio absorbing composite materials based on powdered charcoals are presented. The technique is based on layer-by-layer pouring of mixtures of a gypsum binder and powdered charcoal (non-activated birch, activated birch, activated coconut) into molds in the order in which the outer (relative to the electromagnetic radiation propagation front) layer of the composite material is characterized by the lowest wave resistance, and the inner layer is characterized by the highest wave resistance. The specified order is determined by the results of the theoretical substantiation of the developed technique. In the course of its experimental substantiation, regularities for changing the electromagnetic radiation reflection and transmission coefficients values of the manufactured materials depending on the value of the radiation frequency in the range of 0.7–17.0 GHz have been established. Based on the established regularities, it was stated that the minimum value of the electromagnetic radiation reflection coefficient of the two-layer materials manufactured according to the developed and substantiated technique (thickness ~ 5.0 mm) is –12.0 ± 1.0 dB and corresponds to electromagnetic radiation frequencies of 0.8 and 2.6 GHz (it’s provided, when such materials are fixed on metal substrates). The minimum value of the electromagnetic radiation reflection coefficient of the three-layer materials (thickness ~ 10.0 mm) under the specified condition is also –12.0 ± 1.0 dB and corresponds to electromagnetic radiation frequencies of 4.5 and 6.0 GHz. The electromagnetic radiation transmission coefficient values of such materials decrease with an average step of 4.0 dB as the frequency of the radiation increases by 1.0 GHz in the range of 2.0–10.0 GHz and increase with a similar step as the frequency increases by 1.0 GHz in the range of 10.0–17.0 GHz. The minimum value is –30.0 ± 2.0 dB. The materials manufactured according to the developed and substantiated technique seem to be promising for ensuring the protection of electronic devices from the effects of electromagnetic interference (both active and passive types).

Перспективные слоистые гибкие радиопоглощающие материалы на основе порошкообразного угля

The article presents the technique for obtaining advanced layered radio-absorbing materials based on powdered charcoal. The technique includes the following technologies: incorporation of the electrolyte aqueous solution into the material particles pores; adhesive pressing. The developed technique is more manufacturable compared to the analogs. Materials obtained in accordance with this technique are characterized by the flexibility, as well as lower cost compared to other carbon-containing radio-absorbing materials. The experimental characteristics of electromagnetic radiation reflection and transmission coefficients in the frequency range 2.0 – 17.0 GHz of the materials obtained in accordance with the developed technique are described. The results of the comparative analysis of these characteristics are provided. Based on these results, it’s determined that the average values of electromagnetic radiation reflection coefficient in the specified frequency range of the materials based on powdered non-activated wood charcoal, powdered activated wood charcoal and powdered activated coconut charcoal are –4.5 dB, –8,5 dB and –9.0 dB (when these materials fixed on metal reflectors). The average values of their electromagnetic radiation transmission coefficient are –11.5 dB, –20.0 dB and –15.5 dB respectively. The investigated materials seem to be promising for use in order to protect electronic equipment from external electromagnetic interference.

Wide-Band Electromagnetic Radiation Shielding Construction Based on Pseudooval Scattering Elements for Information Protection Against Leakage Via Electromagnetic Channel

The paper considers the results of a study of the influence of the relative position of moisture-containing pseudooval scattering elements with linear dimensions of 10…20, 2…4, 1…4 and 1…2 mm on the electromagnetic radiation reflection coefficients values of the electromagnetic radiation shielding structures, including these elements, and the effective scattering surface of the ground objects, on the surface of which the indicated structures are fixed or applied. Placement of three- or two-layer structures formed on the basis of pseudooval elements with linear dimensions of 2...4, 1...4, 1...2 mm, between two monolayers made on the basis of elements with dimensions of 10...20 mm, leads to the decrease up to –17,6 dB of the electromagnetic radiation reflection coefficients values in the frequency range of 2–12 GHz of the electromagnetic radiation shielding structures, including these elements. The values of the effective scattering surface of ground objects, on the surface of which the indicated electromagnetic radiation shielding structures are located, vary within 0,08...11,80 m 2 , which is the reason of a significant difficulty in intercepting information about the location and characteristics of ground objects by means of technical intelligence in the frequency range of their operation.

Microwave studies of reflective coatings based on natural graphene-like carbon

In this work, shielding coatings based on graphene-like carbon films have been investigated. To design the shielding, the Costas massif theory is applied. For microwave studies, the method of recording standing waves with a microwave interferometer was used. The resulting coatings are safe, durable, ecological and have an electromagnetic radiation reflection coefficient of 10-20 dB.

Synergy-induced tunable electromagnetic response and enhanced shielding efficiency in carbon black- and carbonyl iron-reinforced polydimethylsiloxane composites

This work reports the broadband (10 MHz-1 GHz) electromagnetic response and Electromagnetic Interference (EMI) shielding of PDMS- based meta-composites of conducting carbon black (CB) and magnetic carbonyl iron (CI). The prominent inductive character resulting from the three-dimensionally extending conducting network results a transition to negative permittivity in the composites and its frequency can be tuned with the content of CI. Moreover, the combined effect of magnetic resonance in CI as well as the formation of current loops inside the conducting network results a negative permeability in the composites. The Electromagnetic interference (EMI) shielding effectiveness (SET) of the composite is found to progressively improve with CI addition; SET> 60 dB (99.9999%) is obtained for PDMS-CCI@80. A detailed investigation on the absorption as well as the reflection coefficient indicates that the increase in the EMI SE in the composite is strictly based on the dominating microwave absorption mechanisms. Out of the 64 dB obtained for 3 mm thick PDMS-CCI@80, 59.4 dB is due to absorption and 4.6 dB corresponds to the reflection of electromagnetic radiation.

Glass composite modified with silicon carbide and gallium arsenide, that absorbs electromagnetic radiation

The possibility of using waste of semiconductor manufacturing containing silicon carbide and gallium arsenide as an effective additive in radio absorbing material preparation was established as a result of research. The resulting material meets the requirements of effective porous electromagnetic radiation absorbers of extremely high frequency range: maximum absorption and minimum reflection of electromagnetic radiation, fire safety, the minimum allowable level of toxic and hazardous substances.

Methods for Substantiating the Electrodynamic and Design Parameters of Absorbing Materials of Waveguide Type

The paper considers the issues related to the microwave diffraction on periodic structures of waveguide type. An approach used for assessing the reflective characteristics of absorbing material is proposed. This approach is based on the assumption that in accordance with the energy conservation law, the entire power of the incident microwave radiation on the absorbing material is distributed into two components. One of them characterizes electromagnetic radiation reflection from material surface and is determined through wave impedance at the interface “medium – absorbing material”, and the other, obeying the law of electromagnetic waves diffraction on nonperfectly conducting closed surfaces of waveguide type, propagates into the lattice, then it is partially absorbed in the bulk of the material and reflected from the object (metal substrate), after which it is summed with the first component at the output. A feature of the proposed technique is the design ratios, allowing to determine rational values of dielectric permeability of material, lattice elements conductivity as well as the period and thickness of the lattice which enable to achieve “a semi-infinite layer” at which the minimum value of material reflection coefficient is observed and its no longer depends on the presence or absence of an object (metal substrate)

Modeling the Interaction of Solit-Like Pulse Signals with Electromagnetic Shields in the Form of Heterogeneous Media

Modeling of electromagnetic radiation interaction with electromagnetic shields is an important problem that is solved during their development. By solving this problem, as a rule, it is possible to reduce the time and financial costs necessary to obtain electromagnetic shields, characterized by the required electromagnetic radiation attenuation and reflection coefficient. Currently, electromagnetic shields are usually developed in the form of heterogeneous media, which is due to lower the values of electromagnetic radiation reflection coefficient of such shields in comparison with the shields in the form of homogeneous media made in the form of continuous materials sheets. The authors of the article have proposed a new approach to modeling of electromagnetic radiation interaction with electromagnetic shields in the form of heterogeneous media. This approach is based on the use of difference schemes of end-to-end counting without explicitly distinguishing the interface between adjacent media, fulfilling the conditions of equality of full currents and charge flows on this boundary, and also on describing electromagnetic waves in the form of soliton-like signals, characterized by a greater penetration depth compared to other waves used in currently in the process of modeling (rectangular, sawtooth, etc). When using soliton-like signals that take into account broadening of spectral lines, the matching conditions for the first initial-boundary-value problem are satisfied. The existing software packages for electrodynamic tasks solving don’t take into account the matching conditions. On the base of the proposed approach, using the COMSOL Multiphysics software package, the authors first simulated the electromagnetic radiation interaction with a silver-based shield, the surface of which is rough and characterized by roughness sizes significantly smaller than the length of electromagnetic waves interacting with them, and with a shield in the form of a copper plate, the surface of which has slots, diameters and the depth of which is much less than the length of the electromagnetic waves interacting with them. The selection of these objects of study is due to the wide use of copper and silver for the electromagnetic shields manufacture, as well as the prospects for the development of shields formation technology, which consists in the heterogenization of the solid sheet metal materials surface.

ELECTROMAGNETIC AND SOUND INSULATION PROPERTIES OF COMBINED SHIELDS BASED ON THE NEEDLE-PUNCHING MATERIAL AND FRAGMENTS OF ALUMINUM FOIL

A method for creating the electromagnetic radiation shields, which consists in fixing fragments of aluminum foil on the surface of a needle-punched carbon-containing material has been proposed. In accordance to the proposed method the shield samples have been made. The fragments of the used aluminium foil were in the form of rectangles or half rings the overall dimensions of which didn't exceed 20 mm. Using an automated meter of transmission and reflection coefficients SNA 0.01–18, shielding characteristics in the frequency range 0.7–17 GHz of the shield samples made in accordance with the proposed method have been obtained. Using the measuring stand, the main components of which were a white noise generator, power amplifier, speaker, sound analyzer MANOM-2, in the frequency range 20–16000 Hz, the soundproofing properties of the shield samples made in accordance with the proposed method have been obtained. It was shown that the values of the electromagnetic radiation reflection coefficients in the frequency range of 0.7–17 GHz of the investigated shields vary from –0.5 to –19.0 dB, and the electromagnetic radiation transmission coefficient in the specified frequency range vary from –2.0 up to –18.0 dB. It was found that the of electromagnetic radiation reflection coefficient values in the frequency range 0.7–17 GHz and the electromagnet radiation transmission coefficient values in the frequency range 6–17 GHz of the shields made in accordance with the proposed method using fragments of aluminum foil in the form of half rings, by 1,0–6.0 dB below the same values of the shields made using fragments of aluminum foil in the form of rectangles. It was determined that the studied shields provide sound attenuation by 2–3 dB in the frequency range from 20–16000 Hz. In view of the obtained results, shields manufactured in accordance with the proposed method are recommended for use in order to protect information circulating in the premises from leakage through the acoustic channel and the channel of secondary electromagnetic radiation.

The pseudo-limit problem existing in electromagnetic radiation transmission and its mathematical physics principle analysis

Abstract In the study of electromagnetic radiation transmission for large airflow layers, it is found that not all electromagnetic waves are capable of forming waveguide propagation, and have a limit value problem. This is because whether electromagnetic waves propagating in the atmosphere can be captured by the atmospheric waveguide generated under specific meteorological conditions into the waveguide layer, depending on the wavelength (frequency) of the electromagnetic wave, the relative position of the emission source and the evaporating waveguide. And parameters such as the emission angle of the source. When the angle of incidence of the sun and the angle of observation are at a horizontal level, the amplitude of the electromagnetic radiation reflection is not unique. From a mathematical point of view, the limit value is not unique or the limit value is discontinuous, which is called the pseudo limit problem. This electromagnetic transmission pseudo-limit problem is a mathematical physics principle that ignores the physical principles implied in electromagnetic radiation. Based on this background, the paper studies the influencing factors of the pseudo-limit problem of electromagnetic transmission in large airflow layer, and analyzes the mathematical physics principle in the pseudo-limit problem by using Snell’s optical law.

ELECTROMAGNETIC RADIATION REFLECTION AND TRANSMISSION CHARACTERISTICS OF TWO-LAYER STRUCTURES BASED ON TRANSITION METAL OXIDES

The aim of the work, the results of which are presented in the framework of the article, was to study the of electromagnetic radiation interaction laws in the frequency range 0.7…17 GHz with two-layer structures, the surface layer of which was made using powdered titanium dioxide, and the inner layer was made using a powder material based on oxide ferric iron. The thickness of the layers of the studied structures varied from 0.3 to 1 cm. To achieve this goal, theobjectives associated with the development of a methodology for the manufacture of multilayer structures based on composite materials containing transition metal oxides, as well as with the measurement of such structures samples electromagnetic radiation reflection and transmission coefficients in the frequency range 0.7...17 GHz. These measurements were carried out using a panoramic meter of reflection and transmission coefficients SNA 0.01–17. Based on the obtained measurement results, it was shown that in the frequency range 0.7…2 GHz, the lowest values of electromagnetic radiation reflection coefficient, reaching –20 dB, are characterized by structures whose surface layer thickness is 1 cm, and in the range 2 ... 17 GHz – structures, thickness the surface layer of which is 0.5 or 1 cm (depending on the thickness of the inner layer). The values of electromagnetic radiation transmission coefficient in the frequency range of 0.7...17 GHz of such structures reach –23 dB. Based on the results of the study, it is proposed to use the considered structures in the process of creating shielded rooms or improving the latter (for example, in cases, when it's necessary to reduce the level of passive interference in rooms shielded with metal materials).

A study of flat stick bamboo microwave absorber performance

Microwave absorber able to inhibit the reflection of electromagnetic radiation. Microwave absorbers are used in an anechoic chamber along with its wall, ceiling and floor for the electromagnetic compatibility (EMC) and electromagnetic interference (EMI) evaluation. This research is to develop a flat shape of biomass absorbers using an agricultural material. The main material used in constructing the flat absorber is a natural bamboo. The flat shaped absorber is chosen because it could reach the standard set in the specified industry and suitable to be used in the microwave frequency range. Cylindrical bamboo with different radius have been used for this study. Radius 0.2 cm for Design 1 and 1 cm for Design 2. The range of frequencies are set in the range from 1 GHz to 12 GHz. The result of microwave absorber is analyzed for its absorption performance. The generated result from the technique shows that the flat stick bamboo microwave absorber operates the best in Design 2 with 34.9% of absorption performance compared with Design 1. The overall results in different angles for both designs are analyze and compared.