RU2541225C2 - Protection device for computer technology facilities against electromagnetic interference - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: invention is referred to the sphere of protection against electromagnetic interference (EMI) and may be used for protection of computer technology facilities (CTF) of information and communication systems against impact of external and stray electromagnetic radiation (SEMR). A multilayer honeycomb straightener is used with fabrication inhomogenuities made in the form of hollow rectangular prisms with cross-section shaped as staggered regular hexagons and of radar absorbent composite materials.

EFFECT: higher screen factor.

3 dwg

Description

The invention relates to the field of protection against electromagnetic radiation (EMR) and can be used to protect means of electronic computer technology (EECS) of objects of infocommunication systems from the effects of external and secondary electromagnetic radiation (PEMI) EECS.

The well-known "Multilayer electromagnetic screen" (patent RU 85267 U1, Published: July 27, 2009), which is a multilayer electromagnetic screen containing two externally arranged flat shielding layers, each of which is made of sheet magnetically soft isotropic steel, and placed between them, at least at least one volumetric shielding layer in the form of a rectangular steel grating made with the possibility of its cells functioning as transcendental waveguides with respect to the fundamental frequency harmonic of the screened field I, which allows protection against low-frequency EMP.

The disadvantage of this screen is the relatively low shielding coefficient.

The closest in technical essence and the functions performed is the "Device for protection against electromagnetic radiation" (patent RU 100338 U1, Published: December 10, 2010), containing three shielding layers arranged in series, each of which contains cells that are transcendental waveguides, the corresponding the cells of each layer are a continuation of the cells of the previous layer, and the layers themselves, respectively, are made as "polymer-metal-polymer", while the transcendent waveguides are made with a cross section of a rectangular rmy and combined into a honeycomb lattice. This device is taken as a prototype.

The disadvantage of this prototype is the relatively low shielding coefficient of the electromagnetic screen, which is due to the shape and mutual influence of transcendental waveguides.

The objective of the invention is to provide a device for protecting electronic computers from electromagnetic radiation, which allows to increase the shielding coefficient.

This problem is solved in that the device for protecting electronic computers from electromagnetic radiation, containing three consecutive shielding layers, each of which contains cells that are transcendental waveguides, and the corresponding cells of each layer are a continuation of the cells of the previous layer, and the layers themselves, accordingly, they are made as “polymer-metal-polymer", transcendental waveguides are made in the form of hollow direct prisms with a cross section in the form of regular hexagons, while in each layer, these waveguides are staggered and parallel to each other.

The listed new set of essential features makes it possible to increase the screening coefficient of the electromagnetic screen by changing the shape of the cells and their location in a checkerboard pattern in a multilayer shielding structure.

The analysis of the prior art made it possible to establish that analogues that are characterized by a combination of features identical to all the features of the claimed technical solution are absent, which indicates the compliance of the claimed device with the patentability condition of "novelty".

Search results for known solutions in this and related fields of technology in order to identify features that match the distinctive features of the claimed object from the prototype showed that they do not follow explicitly from the prior art. The prior art also did not reveal the popularity of the impact provided by the essential features of the claimed invention, the transformations on the achievement of the specified technical result. Therefore, the claimed device meets the condition of patentability "inventive step".

"Industrial applicability" of the device is due to the presence of the element base, on the basis of which the devices can be made, with the achievement of the destination specified in the invention.

The claimed device for protection against electromagnetic radiation is illustrated by drawings, which show:

figure 1 - the process of reflection and refraction of an electromagnetic wave passing through the device, where 1, 2, 3 - respectively, the first, second and third layers of the device; 4 - transcendental waveguides; δ ₁ , δ ₂ , δ ₃ - the thickness of the corresponding layer of the device; I ₁ , I ₂ , I ₃ , I ₄ - respectively, the points at the interfaces of the media "air-polymer, polymer-metal, metal-polymer, polymer-air"; P ₁ - incident plane wave; P ₂ , P ₃ , P ₄ , P ₅ - waves, respectively, undergoing refraction in the media "polymer, metal, polymer, air"; P _Otr1 , P _Otr2 , P _Otr3 , P _Otr4 — waves, respectively, reflected in “air, polymer, metal, polymer” media; E ₁ , E ₂ , E ₃ , E ₄ , E ₅ - the electric intensity of the electromagnetic field corresponding to various environments: "air-polymer-metal-polymer-air"; E ₁₂ , E ₂₃ , E ₃₄ , E ₄₅ - electric intensity of the electromagnetic field of the reflected waves in the respective environments: "air-polymer-metal-polymer-air"; H ₁ , H ₂ , H ₃ , H ₄ , H ₅ — magnetic fields of electromagnetic field corresponding to various media: “air-polymer-metal-polymer-air”; H ₁₂ , H ₂₃ , H ₃₄ , H ₄₅ - magnetic intensity of the electromagnetic field of the reflected waves in the respective environments: "air-polymer-metal-polymer-air";

figure 2 is a fragment of the wall of the device, where 1, 2, 3 are, respectively, the first, second and third layers of the device; 4 - transcendental waveguides; q is the diameter of the circle described near the cross-section of the transcendental waveguide in the form of a regular hexagon; δ _ecr is the thickness of the device;

figure 3 is a cross-section of the device in a plane in the direction AA, where 1, 2, 3 are, respectively, the first, second and third layers of the device made of materials "polymer-metal-polymer"; 4, 5, 6 - transcendental waveguides in the form of hollow straight prisms with a section in the form of regular hexagons, and located in each layer in a checkerboard pattern and parallel to each other, the cells of each layer being an extension of the cells of the previous layer; 7 - joints during spraying from the outer and inner sides of the metal layer for communication between the layers.

The protection device from electromagnetic radiation operates as follows.

In the process of incidence of a plane electromagnetic wave on the device layer 1 from the free space side (Fig. 1), shielding in a multilayer structure occurs due to attenuation due to reflection, absorption and repeated re-reflections of the electromagnetic wave from the surfaces of layers 1, 2 and 3 of the device, with the overall coefficient shielding is defined by formula (I):

$${\eta }_{\Sigma }\left[dB\right]={\eta }_{\mathrm{about}tR}+{\eta }_{P\mathrm{about}gl}+{\eta }_{m\mathrm{about}tR},\left(\mathrm{one}\right)$$

раз меньше, чем в точке на поверхности конструкции (I₁) (фиг.1), где δ - эквивалентная глубина проникновения. Волна P₁, попадая в запредельные волноводы 4 в виде полых прямых призм с сечением в форме правильных шестиугольников, сильно затухает на критических частотах $$f_{кр}^{mn}$$

, лежащих ниже известного предела (Лебедев И.В. Техника и приборы СВЧ. - М.: Высшая школа, 1970. - стр.31; Б.Ф.Емелин, Б.М.Машковец. Основы техники СВЧ. - СПб.: ВАС, 1975. - стр.32-35).where η _sp - attenuation coefficient due to reflection; η _sw - the attenuation coefficient due to absorption; η _motor is the attenuation coefficient due to repeated reflections (Bogush V.F., Lynkov L.M. Electromagnetic radiation. Methods and means of protection. - Мn .: Bestprint, 2003. - p. 119; Knyazev A.D. Design of electronic and electronic -computing equipment taking into account electromagnetic compatibility. - M .: Radio and communications, 1989. - p. 45). Between the transcendental waveguides 4, 5, 6 (Fig.2, 3) in the shielding structure there is a mutual influence, leading to an increase in the total resistance of the entire screen, which entails an increase in the shielding coefficient of the entire structure as a whole. In an incident plane wave P _{1, the} vectors of the electric E ₁ and magnetic H ₁ fields are parallel to the plane of the layer. At point I ₁ (Fig. 1), located at the interface between the air-polymer media, the wave P _{1 is} partially reflected (wave P _OT1 ) and partially refracted (wave P ₂ ). Propagating in the first layer, the refracted wave P ₂ decays exponentially, and by the time the next interface between the polymer-metal media is reached, the intensities of both fields will be $$e^{{\delta }_{\mathrm{one}}/\delta }$$

times less than at a point on the surface of the structure (I ₁ ) (figure 1), where δ is the equivalent penetration depth. The wave P ₁ , falling into the transcendental waveguides 4 in the form of hollow direct prisms with a cross section in the form of regular hexagons, strongly attenuates at critical frequencies $$f_{\mathrm{to}R}^{mn}$$

lying below a known limit (Lebedev I.V. Microwave equipment and instruments. - M .: Higher school, 1970. - p. 31; B.F. Emelin, B.M. Mashkovets. Fundamentals of microwave technology. - St. Petersburg: YOU, 1975 .-- pp. 32-35).

раз меньше, чем на входе в устройство. Преломленная волна Р₃ (фиг.1), распространяясь во втором металлизированном слое 2, попадая в запредельные волноводы 5 (фиг 2, 3) в виде полых прямых призм с сечением в форме правильных шестиугольников, также затухает по экспоненциальному закону, и к моменту достижения следующей границы раздела сред «металл-полимер» точка I₃, напряженности обоих полей будут в $$e^{{\delta }_2/\delta }$$

раз меньше, чем в точке I₂, На выходе волны Р₃ из слоя 2, точка I₃, снова произойдет преломление (волна Р₄) и отражение (волна Р_отр3) от границы сред «металл-полимер» (фиг.1, 3). Преломленная волна P₄ войдет в третий слой 3, попадая в запредельные волноводы 6 в виде полых прямых призм с сечением в форме правильных шестиугольников, затухает на критических частотах $$f_{кр}^{mn}$$

, лежащих ниже известного предела, и в значительно меньшей степени затухает на частотах, лежащих выше данного предела, а отраженная Р_отр3 будет затухать, и в точке на внешней поверхности этого слоя 3 из полимера напряженности полей будут в $$e^{2{\delta }_2/\delta }$$

раз меньше, чем на входе в этот слой устройства. Преломленная волна Р₄ также затухает по экспоненциальному закону и к моменту достижения следующей, последней границы раздела сред типа «полимер-воздух», точка 14 (фиг.1), напряженности обоих полей будут в $$e^{{\delta }_3/\delta }$$

раз меньше, чем в точке I₃. На выходе волны Р₄ из третьего слоя экрана, точка I₄, снова произойдет преломление (волна Р₅) и отражение (волна Р_отр4) от границы сред «полимер-воздух». Отраженная волна Р_отр4 будет затухать и в точке на внешней поверхности этого последнего слоя напряженности полей будут в $$e^{2{\delta }_3/\delta }$$

раз меньше, чем на входе в этот слой полимера. Все это время в устройстве будут происходить отражения волн от границ раздела сред до их полного затухания в теле устройства. В экранируемое пространство будут проникать преломленные волны Р₅. Их суммарное воздействие определяет напряженности полей Е₅ и H₅ в этом пространстве. При этом все перечисленные процессы сопровождаются потерями энергии волны.When the wave P ₂ passes from the first layer of the structure, point I ₂ , refraction (wave P ₃ ) and reflection (wave P _OTR2 ) from the boundary of the polymer-metal media will again occur (Fig. 1). The refracted wave P ₃ will pass into the second metallized layer of the device, and the reflected P _sp2 will _attenuate , and at a point on the outer surface of this layer 2, the field strengths will be $${\mathrm{<figure-callout\; id="2"\; label="e"\; filenames="00000016.png,00000017.png"\; state="\{\{state\}\}">e</figure-callout>}}^{2{\delta }_{\mathrm{one}}/\delta }$$

times less than at the entrance to the device. The refracted wave P ₃ (Fig. 1), propagating in the second metallized layer 2, falling into the transcendental waveguides 5 (Figs. 2, 3) in the form of hollow direct prisms with a cross section in the form of regular hexagons, also attenuates according to the exponential law, and by the time it reaches of the next metal-polymer interface, point I ₃ , the intensities of both fields will be in $${\mathrm{<figure-callout\; id="2"\; label="e\; \delta "\; filenames="00000016.png,00000017.png"\; state="\{\{state\}\}">e\; </figure-callout>}}^{{\delta }_{}}$$

times less than at point I ₂ , At the output of wave P ₃ from layer 2, point I ₃ , refraction (wave P ₄ ) and reflection (wave P _OTR3 ) from the metal-polymer media boundary again occur (Fig. 1, 3). The refracted wave P ₄ will enter the third layer 3, getting into the transcendental waveguides 6 in the form of hollow direct prisms with a cross section in the form of regular hexagons, attenuates at critical frequencies $$f_{\mathrm{to}R}^{mn}$$

lying below the known limit, and to a much lesser extent attenuates at frequencies lying above this limit, and the reflected P _sp3 will _attenuate , and at a point on the outer surface of this polymer layer 3 of the field strength will be $${\mathrm{<figure-callout\; id="2"\; label="e"\; filenames="00000016.png,00000017.png"\; state="\{\{state\}\}">e</figure-callout>}}^{2{\mathrm{<figure-callout\; id="2"\; label="\delta "\; filenames="00000016.png,00000017.png"\; state="\{\{state\}\}">\delta </figure-callout>}}_2/\delta }$$

times less than at the entrance to this layer of the device. The refracted wave P ₄ also decays exponentially, and by the time the next, last polymer-air interface is reached, point 14 (Fig. 1), the intensities of both fields will be in $${\mathrm{<figure-callout\; id="3"\; label="e\; \delta "\; filenames="00000016.png,00000017.png"\; state="\{\{state\}\}">e\; </figure-callout>}}^{{\delta }_{}}$$

times less than at point I ₃ . At the output of wave P ₄ from the third layer of the screen, point I ₄ , refraction (wave P ₅ ) and reflection (wave P _sp4 ) from the boundary of the polymer-air media will occur again. The reflected wave P _spr4 will _attenuate and at a point on the outer surface of this last layer the field intensities will be $${\mathrm{<figure-callout\; id="2"\; label="e"\; filenames="00000016.png,00000017.png"\; state="\{\{state\}\}">e</figure-callout>}}^{2{\mathrm{<figure-callout\; id="3"\; label="\delta "\; filenames="00000016.png,00000017.png"\; state="\{\{state\}\}">\delta </figure-callout>}}_3/\delta }$$

times less than at the entrance to this polymer layer. All this time, the device will reflect waves from the media to their complete attenuation in the body of the device. Refracted waves P ₅ will penetrate into the screened space. Their total effect determines the field strengths E ₅ and H ₅ in this space. Moreover, all these processes are accompanied by loss of wave energy.

In order to obtain the maximum shielding coefficient, the transcendental waveguides 4, 5, 6 (Figs. 2, 3) of the multilayer shielding design are made in the form of hollow straight prisms with a cross section in the form of regular hexagons arranged in a checkerboard pattern and parallel to each other, and transcendental waveguides of each layer are a continuation of the transcendental waveguides of the previous layer. This is justified by the fact that with their specific location, the ratio between the dimensions of the transcendental waveguides and their ratio with the dimensions of the shielding structure and the wavelength λ of the electromagnetic field, the possibility of its penetration into the device is practically excluded. The screening coefficient of such a shielding design is determined by the following well-known expression (2) (A. Chernushenko, Designs of microwave devices and screens. - M.: Radio and communications, 1983. - p. 145, 156, 170):

$${\eta }_{\left(E\left(H\right)\right)}\left[dB\right]=A_M\cdot \left[A_{\max }\left[dB\right]+\mathrm{twenty}\cdot \lg \left[S_{\mathrm{at}}\cdot G\cdot \mathrm{TO}\cdot N_{\mathrm{at}}\right]\right],\left(2\right)$$

where A _M is an approximating factor, determined on the basis of experimental data obtained during the tests, depends on the wavelength and characteristics of electromagnetic radiation; S _max - attenuation introduced by the shielding structure with transcendental waveguides in the form of a prism, is determined by the following expression:

$$S_{\max }\left[dB\right]=27\cdot \frac{\mathrm{one}}{q}-\mathrm{twenty}\lg N,\left(3\right)$$

where N is the number of cells in the shielding structure.

The attenuation introduced by one transcendental waveguide in the form of a hexagon S _B [dB] is determined using the following well-known expression (Grigoryev AD, Yankevich VB Resonators and resonator slowdown microwave systems: numerical methods of calculation and design. - M .: Radio and communications, 1984. - p. 88):

$$S_{\mathrm{at}}\left[dB\right]=\frac{{\left(Z_{H(E)}^{mn}\cdot \lambda \right)}^2+{\mathrm{<figure-callout\; id="2"\; label="q"\; filenames="00000016.png,00000017.png"\; state="\{\{state\}\}">q</figure-callout>}}^2}{\mathrm{four}q\cdot Z_{H(E)}^{mn}\cdot \lambda },\left(\mathrm{four}\right)$$

(Ом) - характеристическое сопротивление запредельного волновода для волн типа H_mn и E_mn; Г - поправочный коэффициент отражения запредельного волновода в виде полой прямой призмы с сечением в форме правильного шестиугольника, зависящий от изменения характеристического сопротивления заполняющей ее среды Z_c и характеристического сопротивления для волн различного типа $$Z_{H(E)}^{mn}$$

; λ - длина волны воздействующего электромагнитного поля.Where $$Z_H^{mn}$$

(Ohm) is the characteristic resistance of the transcendental waveguide for waves of type H _mn and E _mn ; G - correction coefficient of reflection of the transcendental waveguide in the form of a hollow straight prism with a cross section in the form of a regular hexagon, depending on the change in the characteristic resistance of the medium filling it Z _c and the characteristic resistance for waves of various types $$Z_{H(E)}^{mn}$$

; λ is the wavelength of the acting electromagnetic field.

The mutual influence of transcendental waveguides on each other is taken into account using the correction coefficient K (Shabunin S.N., Solovyanova I.P. Waveguides and cavity resonators. - Yekaterinburg: Ural State Technical University, 1998. - p. 220). The correction factor for the number of transcendental waveguides N _in takes into account the multilayering of the shielding structure and determines the required number of transcendental waveguides in it, depending on the limit (criteria) requirements for shielding quality, geometric dimensions and electrophysical properties used for shielding materials.

A calculation and an experiment were carried out to determine the screening coefficient η _{(E (H)) of the} claimed device, defined by expression (2), using the Mathcad engineering calculation environment and electromagnetic radiation simulators, respectively, taking into account design features with the following initial data:

- frequency of electromagnetic radiation f = 1 GHz (GOST R 53115-2008. Information protection. Tests of technical means of information processing for compliance with the requirements of security against unauthorized access. Methods and tools);

- a constant decline in electromagnetic radiation α = 4 · 10 ⁶ s ^-1 and a constant increase in electromagnetic radiation β = 5 · 10 ⁸ s ^-1 (Myrova L.O., Chepizhenko A.Z. Ensuring the stability of communication equipment to ionizing and electromagnetic radiation. 2nd ed., Revised and revised - M .: Radio and communications, 1988. - S.36-38 .: ill.);

- approximating factor A _M = 1,707 (Shapiro D.N. Fundamentals of the theory of electromagnetic shielding. - L .: Publishing house "Energy", 1975. - p. 68);

- the geometric dimensions of the device for protecting electronic computers from electromagnetic radiation (figure 2):

- δ _ecr = 0.006 m is the thickness of the device;

- δ _1,2,3 = 0,002 m the thickness of each of the layers of the device;

- q = 0.006 m is the diameter of the circle described near the cross-section of the transcendental waveguide in the form of a regular hexagon;

- the number of waveguides N = 675;

- magnetic constant µ ₀ = 4π · 10 ^-7 GN / m and electric constant ε ₀ = 8.85418782 · 10 ^-12 F / m (Voznyuk M.A., Kiselev A.A., Snezhko V.K. Brief thematic Handbook of units of measurement and designation of physical and technical quantities. - SPb .: VUS, 2000. P.58);

- magnetic permeability of a three-component hybrid polymer composite (GPC) µ = 4 and electrical conductivity of the GPC σ = 10 ² (Bespyatykh Yu.I., Kazantseva N.E. Electromagnetic properties of polymer hybrid composites // Radio engineering and electronics. No. 2, 2008, volume 53 S.162-164);

- dielectric permeability of HPA ε≈2.8-3 (Pirumov V.S., Alekseev A.G., Aizikovich B.V. New radio-absorbing materials and coatings // Successes of modern radio electronics, No. 2, 2000. - P.60- 68; Berlin, A.A. Modern polymer composite materials.Moscow State University, Sorov educational journal, No. 1, 1995. - P. 57-65; Mikhailovsky L.K. Radar absorbing current-free media, materials and coatings (electromagnetic properties and practical application) // Successes of modern radio electronics, No. 9, 2000. - P.21-27.).

- the initial relative magnetic permeability of magnetically soft isotropic steel µ = 2 × 10 ³ (TU 14-1-4592-89).

The results of calculations and experiment showed that the screening coefficient of the shielding structure with cells in the form of hollow straight prisms with a section in the form of regular hexagons is η _{(E (H))} = 100 dB.

The efficiency of the invention in comparison with the prototype device can be characterized by the ratio of the shielding coefficient of the prototype device and the proposed device. We denote this relation by the letter _η . The prototype device ("Device for protection against electromagnetic radiation", patent RU 100338 U1, Published: 12/10/2010) provides a shielding coefficient of up to 85 dB. Denote it by η _prot. From here we get:

$$E_{\eta }=\frac{{\eta }_{(H(E))}-{\eta }_{PR\mathrm{about}t}}{{\eta }_{(E(E))}}\cdot \mathrm{one\; hundred}\%=\frac{\mathrm{one\; hundred}dB-85dB}{\mathrm{one\; hundred}dB}\cdot \mathrm{one\; hundred}\%=\mathrm{fifteen}\%$$

Thus, an increase in the screening coefficient of the proposed design η _{(E (H))} by 15 dB gives an increase in the efficiency of the proposed invention compared to the prototype device by 15%.

Claims (1)

A device for protecting electronic computers from electromagnetic radiation, containing three sequentially arranged shielding layers, each of which contains cells that are transcendental waveguides, and the corresponding cells of each layer are a continuation of the cells of the previous layer, and the layers themselves, respectively, are made as " polymer-metal-polymer ", characterized in that the transcendental waveguides are made in the form of hollow straight prisms with a cross section in the form of regular hexagons, while in Each layer indicated waveguides are staggered and parallel to each other.

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