RU2236731C1 - Selective coating for protection against electromagnetic irradiation - Google Patents

Abstract

FIELD: processes and device for protection against electromagnetic irradiation, possibly for lowering level of irradiation harmful for human health in radiotelephones, computers and other apparatuses.

SUBSTANCE: method comprises steps of applying onto both surfaces of dielectric layer stripe metallic chiral members. It is possible to apply adhesive layer along surface of dielectric layer.

EFFECT: intensified suppression of electromagnetic irradiation.

2 cl, 4 dwg

Description

The invention relates to radio engineering, in particular to means of protection against electromagnetic radiation, and can be used to reduce unhealthy radiation levels in cordless phones, computers and other devices for household and special purposes.

A device for absorbing electromagnetic waves / 1 /. It is a surface that is heterogeneous in all directions and consists of capacitive and inductive elements alternating between each other in all directions of this surface.

The disadvantages of this device: the lack of selectivity of absorption of electromagnetic waves, the bulkiness of the design.

A similar device / 2 / for absorbing electromagnetic radiation is also known, consisting of a ferrite substrate and a matching dielectric layer with a carbon filler deposited on it.

The disadvantages of this device: the lack of selectivity of absorption of electromagnetic waves.

The closest in technical essence to the claimed is a device for protection against electromagnetic radiation, comprising three layers of a conductor and two layers of dielectric / 3 / placed in the spaces between them.

The known device does not provide the possibility of selectivity of absorption of electromagnetic waves (EMW), it can not be made optically transparent, and therefore, cannot be used as a protective layer on monitors.

The technical result from the use of the proposed coating is to enhance the suppression of electromagnetic radiation, the creation of an optically transparent coating to protect against electromagnetic waves.

The specified technical result is achieved in that the selective coating for protection against electromagnetic radiation includes one dielectric layer, on both surfaces of which strip metal chiral elements are applied.

The indicated technical result is also achieved by the fact that an adhesive layer is placed along the surface of the dielectric layer.

Figure 1 shows the proposed selective coating.

Figure 2 presents the results of a numerical calculation of the dependences of the modules of the reflection coefficients of the main and depolarized component on the angle of incidence θ of the S-polarization wave on the chiral surface.

Figure 3 shows the dependence of the moduli of transmission coefficients on the angle of incidence θ of the S-polarization wave on the chiral surface.

Figure 4 shows the dependence of the reflection and transmission coefficients of EMW when falling from a strip of chiral elements in the form of letters S on a normalized parameter d / λ (where d is the distance between adjacent chiral elements; λ is the wavelength of the incident EMR).

The selective coating for protection against EMR, shown in figure 1, is a layer of a homogeneous dielectric with relative permittivities ε and μ, respectively, on the surface of which strip metal elements are applied in the form of letters S. Moreover, elements placed on the upper and lower surfaces layer, rotated relative to each other at a certain angle. The distance between the strip elements should be correlated with the wavelength of the incident EMR. Metallization of dielectric surfaces in the form of “gratings” of conductive mirror-asymmetric elements can be performed using the lithography method.

и их зеркальные отражения). Следует отметить, что использование объемных проводящих спиралей в качестве киральных элементов при создании экранирующих покрытий не является технологически выгодным вследствие того, что они должны размещаться внутри диэлектрического слоя. В настоящее время наблюдается рост интереса к исследованию искусственных киральных сред на основе полосковых зеркально-асимметричных элементов /7/. Поэтому нами предлагается в качестве экранирующего покрытия для защиты от ЭМИ использовать полосковые киральные элементы (например, в виде букв S), нанесенные на противоположные поверхности диэлектрического слоя.It is proposed to use an artificial medium with a chirality property / 4-6 / as a shielding coating. The concept of chirality in the broad sense of the word is associated with the manifestation of mirror asymmetry of objects. In chiral electrodynamics, a medium is called, the composition of which includes metal elements of a mirror-asymmetric shape (for example, right- and left-handed spirals, elements in the form of letters

and their mirror reflections). It should be noted that the use of volumetric conductive spirals as chiral elements when creating shielding coatings is not technologically advantageous due to the fact that they must be placed inside the dielectric layer. Currently, there is a growing interest in the study of artificial chiral media based on strip mirror-asymmetric elements / 7 /. Therefore, we propose to use stripe chiral elements (for example, in the form of letters S) deposited on opposite surfaces of the dielectric layer as a shielding coating for protection against EMR.

Consider the basic physical prerequisites for creating a selective coating for protection against electromagnetic radiation based on an artificial chiral medium. It is known that when EMW falls on the chiral layer, its depolarization occurs, that is, the appearance of components in the field of the reflected wave that were absent in the incident wave / 4 /. For example, when the linear S-polarization EMF drops, the reflected wave has elliptical polarization (that is, the components of the P-polarized wave appear). Therefore, when studying the reflection of electromagnetic waves from a chiral medium, reflection coefficients of both the main and the depolarized component are introduced. Figure 2 presents the results of a numerical calculation of the dependences of the modules of the reflection coefficients of the main and depolarized component on the angle of incidence θ of the S-polarization wave on the chiral surface / 5, 6 /. As can be seen from figure 2 for any angle of incidence of electromagnetic waves of S-polarization on the chiral layer, a depolarized (P) rather than the main (S) component of the reflected wave has a large reflection coefficient. Moreover, with a normal incidence of EMW (θ = 0), complete depolarization occurs and a P-polarization wave is reflected.

Figure 3 shows the dependence of the moduli of transmission coefficients on the angle of incidence θ of the S-polarization wave on the chiral surface / 5, 6 /. As can be seen from figure 3, in a chiral medium, two waves propagate with right- and left-circular polarizations having the same amplitudes (at any angle of incidence). As you know, the superposition of such waves is an electromagnetic wave with linear polarization.

As a result, we can conclude: the chiral layer has the ability to change the polarization of the incident wave upon reflection. Moreover, it should be noted that in the general case, when a wave with an elliptical polarization is incident on the chiral layer, its depolarization will also be observed.

The solution and numerical analysis of the problem of EMR diffraction by a “lattice” of strip chiral elements in the form of letters S are carried out in / 7 /. The main conclusion from these studies is the possibility of using strip chiral elements as frequency and polarization-selective coatings. In particular, it can be argued that the wave reflected from the “lattice” of strip chiral elements will have different polarization characteristics when waves with right and left-circular polarizations are incident on it. The frequency selectivity of such a coating is a consequence of the fact that the chirality of the medium appears only in the case when the EMP wavelength correlates with the distance between adjacent chiral elements. Figure 4 shows the dependence of the reflection and transmission coefficients of EME when falling from a strip of chiral elements in the form of letters S on the normalized parameter d / λ (where d is the distance between adjacent chiral elements; λ is the wavelength of the incident EMR) / 7 /. “Lattice” simulates the reflective properties of the upper surface of the layer with chiral elements (figure 1).

As can be seen from figure 4, there is a certain value of the parameter d / λ at which there is a maximum reflection of the depolarized component (dashed line) and a maximum transmission of the main component (solid line). This leads to the important conclusion that, choosing different distances between the chiral elements, you can vary the operating frequencies of the proposed shielding coating. The frequency band is governed by the size of the chiral elements and the distance between them.

Consider the general mechanism of the proposed coating for protection against electromagnetic radiation. When an EMW of arbitrary polarization falls on a “lattice” of strip chiral elements located on the upper surface of the layer, either S or P-polarization wave will be reflected in the outer region I (this depends on the angle of rotation of the chiral elements), and the opposite wave will pass into the dielectric layer polarization (respectively P or S). The “lattice” of chiral elements located on the lower surface of the dielectric layer is rotated relative to the upper “lattice” so that the reflection coefficient for EMW with polarization like that of the transmitted wave (P or S) is close to unity. In this case, EMP will not pass into region III.

Literature

1. Patent RU 2125327 C1, published on 01/20/1999.

2. Patent RU 2169952 C1, published on 06.27.2001.

3. Patent RU 2168879 C1, published on 10.06.2001.

4. Lindell I.V., Sihvola A.H., Tretyakov S.A., Viitanen A.J. Electromagnetic waves in chiral and bi-isotropic media. - London: Artech House, 1994 .-- 291 p.

5. Neganov V.A., Osipov O.V. Reflection of electromagnetic waves from plane chiral structures // Izv. Universities Radiophysics, 1999. - V. 42. - No. 9. - S. 870-878.

6. Neganov V.A., Osipov O.V. Scattering of electromagnetic waves from planar chiral structures // Radiophysics and Quantum Electronics, 1999 .-- V. 42. - No. 9. - R.764-773.

7. Vasiliev T.Ts., Prosvirnin S.L. Diffraction of electromagnetic waves on a flat lattice of chiral strip elements of complex shape // Physics of Wave Processes and Radio Engineering Systems, 1998. - T.1. - No. 4. - S. 5-9.

Claims (2)

1. Selective coating for protection against electromagnetic radiation, comprising one dielectric layer, characterized in that strip metal chiral elements are applied to both surfaces of the dielectric layer. 2. A selective coating for protection against electromagnetic radiation according to claim 1, characterized in that an adhesive layer is introduced along the surface of the dielectric layer.

Images