RU2370866C1 - Antiradar coating - Google Patents

Abstract

FIELD: electric engineering.

SUBSTANCE: invention is related to the field of electric engineering, in particular to antiradar coating, which comprises base from two or more layers of woven thread rows fixed by radio-transparent material, with film applied onto each layer by means of vacuum scattering from hydrogenised carbon with ferromagnetic material particles impregnated in it. Direction of woven thread rows of single layer of woven material makes angle of 60°-120° with direction of woven thread rows of adjacent layer. Content of ferromagnetic material particles makes from 5 wt % in film applied onto external layer of woven thread rows, up to 85 wt % in film applied on layer of woven thread rows adjacent to protected surface.

EFFECT: application of suggested coating provides for improved efficiency of radio absorption with simultaneous reduction of thickness and weight of the whole material with expansion of its application range.

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Description

The invention relates to radio engineering, and more specifically to materials for the absorption of electromagnetic waves, and can be used to increase stealth and reduce the likelihood of detection by radars of objects and equipment of ground, aviation and space technology.

At present, radar absorbing materials are being intensively developed, which absorb incident electromagnetic radiation with finely dispersed conductive particles included in their composition.

Known radar absorbing material (see patent RU No. 2167840, IPC СВВ 35/00, published on 05.27.2001), consisting of a mixture of 0.30-0.45 or 0.55-0.75 molar fractions of strontium titanate and 0.70 -0.55 or 0.45-0.25 molar fractions, respectively, of compounds with the general formula BIMO ₃ , where M is selected from the group of elements including chromium, manganese, iron.

The disadvantage of the known material should be attributed to its significant thickness, necessary for the effective absorption of radio waves.

Known radar absorbing material (see patent RU No. 2107705, IPC C09D 5/32, publ. 03/27/1998) containing latex-based synthetic adhesive "Elaton" as a polymer binder, and powdered ferrite or carbonyl iron as magnetic filler when the following ratio of components, wt.% synthetic adhesive "Elaton" based on latex 80-20, powdered ferrite or carbonyl iron 20-80.

Known radar absorbing material is used for applying on the surface of various geometries products for research, medical and domestic purposes. However, the known radar absorbing material has insufficient absorption of radio waves.

Known radar absorbing material (see US patent No. 6231794, IPC H01Q 17/00, publ. 05/01/2001), comprising a first layer of porous elastic material, such as polyurethane, coated with a second layer of porous elastic material with conductive particles distributed therein, for example graphite particles powders, or particles of carbon material mixed with metal particles.

The disadvantage of the known radar absorbing material is insufficient mechanical strength.

Known radar absorbing coating (see patent DE No. 4140944, IPC H01Q 17/00, publ. 06/17/1993) containing a carrier layer provided with a mass of ferroelectric dipole molecules, as well as control electrodes located on both sides of the carrier layer, of which at least the control electrode located on the side of the radiation, made transparent to radiation.

Known radar absorbing coating has an unnecessarily complicated design.

A known absorber of electromagnetic radiation (see TW No. 285528, IPC H01Q 17/00, publ. 11.08 2007), the basis of which is a cross-linked silicone gel, in which dispersed combustion retardant and an absorber of electromagnetic radiation, introduced in an amount of 200-800 wt.h. per 100 parts by weight silicone gel.

For the effective absorption of electromagnetic radiation requires a large mass of known absorber, which limits its scope.

Known radar absorbing coating (see patent EP No. 1912487, IPC H01Q 17/00, publ. 04/16/2008), comprising a matrix in the form of a thin sheet of organic polymer or inorganic material in which ultrafine carbon particles are dispersed in an amount of 0.01-20, 0 wt.% Of the total weight of the coating, and also contains a filler selected from the group consisting of metal particles, magnesium carbonate, carbon black, carbon fibers, glass fibers or mixtures thereof.

Known radar absorbing material has heterogeneous properties due to the difficulty of uniformly introducing the ingredients into the base.

A known absorber of electromagnetic waves (see patent RU No. 2322735, IPC H01Q 17/00, publ. July 18, 2006) containing a mesh base on which flexible cylindrical elements with radially diverging electrically conductive microdipoles are placed from them. The absorber consists of two interconnected layers, each of which is formed by plain weaving in each mesh of the mesh base of two flexible cylindrical elements, while the ratio between the linear resistance of the microdipoles of the first and second layers is from 2 to 10, and the electrically conductive microdipoles are made of complex filaments with an amorphous ferromagnetic microwire. The length of the conductive microdipole is (0.1-5.0) λ, where λ is the average length of the electromagnetic wave of the operating range.

A disadvantage of the known absorber is the high complexity of manufacturing technology.

A known absorber of electromagnetic waves (see patent RU No. 2323236, IPC H01Q 17/00, publ. July 18, 2006) containing a mesh base into which flexible cylindrical elements are woven with electrically conductive microdipoles radially diverging from them. In each of the cells of the mesh base, plain weaving of two pairs of identical flexible cylindrical elements was performed. The length of the electrically conductive microdipole is (0.3-5.0) λ, where λ is the average electromagnetic wavelength of the operating range. Electrically conductive microdipoles are made of complex glass fiber with a carbon electrically conductive layer.

A disadvantage of the known absorber is the great complexity of manufacturing technology.

Known radar absorbing coating (see patent RU No. 2228565, IPC H01Q 17/00, publ. 10.05.2004), coinciding with the claimed technical solution for the largest number of essential features and taken as a prototype. The prototype coating includes a base in the form of a woven fabric of at least one layer of intertwined aramid high-modulus yarns deposited on the yarns by vacuum spraying a film of hydrogenated carbon interspersed with ferromagnetic clusters in the following ratio, wt.%:

Ferromagnetic clusters 50-80 Hydrogenated carbon rest

A disadvantage of the known radar absorbing coating is the fact that the fabric base of each coating layer inevitably leads to anisotropy of the absorbing properties. In addition, the proposed manufacturing technology of the known radar absorbing coating suggests the presence of gaps between the layers, which leads to the manifestation of instability of the properties.

The objective of the invention is to expand the frequency range and increase the efficiency of radio absorption while reducing the thickness and weight of the entire material and expanding the range of possible applications of the radio-absorbing coating.

This object is achieved in that a radar absorbing coating with a nano-organized structure of each layer includes a base of two or more layers of interwoven rows of threads bonded with radiolucent material, with a hydrogenated carbon film deposited on each layer with particles of ferromagnetic material embedded in it, with the direction of interwoven rows of threads of one layer makes an angle of 60 ° -120 ° with the direction of interwoven rows of threads of an adjacent layer, and the content of particles of ferromagnet Nogo material in said film is from 5 wt.% in the film deposited on the outer layer of interwoven yarns series, up to 85 wt.% in the film deposited on a layer of interwoven yarns rows adjacent to the protected surface.

The rotation of adjacent layers of interwoven rows of threads relative to each other at an angle from 60 ° to 120 ° allows to reduce the anisotropy of the absorbing properties.

The change in the content of the ferromagnetic absorber in the said film from 5 wt.% In the film deposited on the outer layer of the interwoven rows of threads, up to 85 wt.% In the film, deposited on the layer of interwoven rows of threads adjacent to the surface to be protected, provides smooth coordination of the wave impedances of the layers the thickness of the coating, starting from the top layer (matching with the free space), to the last, absorbing layer.

The filaments of the radar absorbing coating may be made of fiberglass or aramid fibers.

A film of hydrogenated carbon with particles of ferromagnetic material embedded in it can be deposited on one side or on both sides of each layer of interwoven rows of threads.

As a ferromagnetic material, a metal selected from the group of 3d elements cobalt, nickel, iron, samarium and their alloys, as well as barium ferrite doped with rare earth elements during the deposition process, nickel-zinc and manganese-zinc ferrites with titanium additives can be introduced.

As a radiolucent material, an adhesive composition based on a rubber or epoxy mixture can be used.

Radar absorbing coating is illustrated by drawings, where:

figure 1 shows a top view of the inventive radar absorbing coating,

figure 2 shows a cross section of the inventive radar absorbing coating,

figure 3 in the table shows the technical characteristics of the inventive radar absorbing coating.

The radar absorbing coating 1 (see FIG. 1, FIG. 2) contains at least two layers, for example, four layers 2a, 2b, 2c and 2d of interwoven rows of threads 3a and 3b. Layers 2a, 2b, 2c and 2d of rows of interwoven yarns 3a and 3b are made, for example, in the form of a woven fabric. The yarns 3a and 3b may be made of fiberglass or aramid fibers. The direction of the rows of threads 3a and 3b, for example, of one layer 2a, makes, with the direction of the rows of the corresponding threads 3a and 3b of the adjacent layer 2b, an angle of φ = 60 ° -120 °. A film of hydrogenated carbon 4 with particles 5 of ferromagnetic material embedded in it is deposited on each layer 2a, 2b, 2c, and 2d by vacuum spraying. Film 4 can be applied on one side of layers 2a, 2b, 2c and 2d or on both sides. The film 4 contains particles 5 of ferromagnetic material in an amount that varies from 5 wt.% In the upper layer 2a to 85 wt.% In the film deposited on the lowest layer 2b adjacent to the surface to be protected. The remaining mass of film 4 is hydrogenated carbon. The film 4 is usually performed with a thickness of 500-1500 nm. Particles 5 of ferromagnetic material (see figure 2), as a rule, have a size of up to 0.05 microns and close to spherical geometric shape. Layers 2a, 2b, 2s, and 2d of rows of interwoven yarns 3a and 3b are fastened with a radiolucent adhesive material 6. The microstructure of the inventive radar absorbing coating was studied using a JSM-35 electron microscope. Particles 5 can be made of any known ferromagnetic material having significant absorption of microwave radiation. As such materials can be used, for example, cobalt, nickel, iron, alloys of these metals, ferrites. The table shows the experimental data on the absorption of microwave radiation by the claimed radar absorbing coating.

Microwave absorption was studied in the frequency range 5–80 GHz on waveguide measuring lines for the case of normally incident electromagnetic (EM) radiation. The real and imaginary parts of the dielectric (ε ', ε ”) and magnetic (μ', μ”) permeabilities and EM wave loss coefficients in reflection (R) were determined: R = -10 · log (W _R / W) dB, where W , W _R - power of the incident and reflected waves, respectively. In order to absorb EM radiation by a granular structure, it is necessary to have large values of ε "and μ", and also the wave impedance Z = [(μ '+ iμ ”) / (ε' + iε”)] ^1/2 must be close to unity. As was established by the authors, the claimed coating has large values of µ ', µ ", ε', ε".

For the manufacture of the inventive radar absorbing coating, any known vacuum sputtering method can be used, for example, laser sputtering, ion sputtering from autonomous ion sources, ion-plasma sputtering, in particular magnetron sputtering of graphite and ferromagnetic targets. Magnetron sputtering, in comparison with other methods of film deposition, has a number of advantages, the main of which are high film growth rate, their good adhesion and low pollution by foreign gas inclusions, low substrate heating temperature, the ability to sputter both conductors and dielectrics and obtain ultrathin films with small radiation defects, as well as low inertia of the process.

Example 1. Received a radar absorbing coating in the form of two layers of interwoven rows of aramid yarns coated with a film of 500 nm thick hydrogenated carbon with cobalt particles embedded in it up to 0.05 μm in size with a cobalt content of 4 wt.% And hydrogenated carbon 96 wt. % in the upper layer and with a cobalt content of 60 wt.% and hydrogenated carbon of 40 wt.% in the lower layer. Films were obtained by magnetron sputtering of graphite and cobalt targets in an argon-hydrogen working medium at a pressure of 5 mTorr, with an argon content of 80 wt.% And hydrogen of 20 wt.%, With an ion current density of 10 ^-2 A / cm ² , a film growth rate of 5 nm / min and with a ratio of carbon and cobalt flows 1.1. The rows of threads in the upper layer made an angle of φ = 60 ° with the rows of threads in the lower layer. The layers were bonded with a rubber compound adhesive. The measurement results of the reflection coefficient (R), the range of absorption frequencies, thickness and weight of the resulting radar absorbing coatings are shown in the table in figure 3.

Example 2. Received a radar absorbing coating in the form of two layers of interwoven rows of aramid yarns coated with a film of 500 nm thick hydrogenated carbon with cobalt particles embedded in it up to 0.05 μm in size with a cobalt content of 5 wt.% And hydrogenated carbon 95 wt. % in the upper layer and with a cobalt content of 60 wt.% and hydrogenated carbon of 40 wt.% in the lower layer. Films were obtained by magnetron sputtering of graphite and cobalt targets in an argon-hydrogen working medium at a pressure of 5 mTorr, with an argon content of 80 wt.% And hydrogen of 20 wt.%, With an ion current density of 10 ^-2 A / cm ² , a film growth rate of 5 nm / min and with a ratio of carbon and cobalt flows of 1: 1. The rows of threads in the upper layer made an angle of φ = 60 ° with the rows of threads in the lower layer. The layers were bonded with a rubber compound adhesive. The measurement results of the reflection coefficient (R), the range of absorption frequencies, thickness and weight of the resulting radar absorbing coatings are shown in the table in figure 3.

Example 3. Received a radar absorbing coating in the form of two layers of interwoven rows of aramid filaments with a 500 nm thick film of hydrogenated carbon coated with cobalt particles up to 0.05 μm in size with a cobalt content of 5 wt.% And hydrogenated carbon 95 wt. % in the upper layer and with a cobalt content of 60 wt.% and hydrogenated carbon of 40 wt.% in the lower layer. Films were obtained by magnetron sputtering of graphite and cobalt targets in an argon-hydrogen working medium at a pressure of 5 mTorr, with an argon content of 80 wt.% And hydrogen of 20 wt.%, With an ion current density of 10 ^-2 A / cm ² , a film growth rate of 5 nm / min and with a ratio of carbon and cobalt flows of 1: 1. The rows of threads in the upper layer made an angle of φ = 90 ° with the rows of threads in the lower layer. The layers were bonded with a rubber compound adhesive. The measurement results of the reflection coefficient (R), the range of absorption frequencies, thickness and weight of the resulting radar absorbing coatings are shown in the table in figure 3.

Example 4. Received a radar absorbing coating in the form of two layers of interwoven rows of aramid filaments with a 500 nm thick film of hydrogenated carbon coated with cobalt particles up to 0.05 μm in size with a cobalt content of 5 wt.% And hydrogenated carbon 95 wt. % in the upper layer and with a cobalt content of 85 wt.% and hydrogenated carbon 15 wt.% in the lower layer. Films were obtained by magnetron sputtering of graphite and cobalt targets in an argon-hydrogen working medium at a pressure of 5 mTorr, with an argon content of 80 wt.% And hydrogen of 20 wt.%, With an ion current density of 10 ^-2 A / cm ² , a film growth rate of 5 nm / min and with a ratio of carbon and cobalt flows of 1: 1. The rows of threads in the upper layer made an angle of φ = 90 ° with the rows of threads in the lower layer. The layers were bonded with a rubber compound adhesive. The measurement results of the reflection coefficient (R), the range of absorption frequencies, thickness and weight of the resulting radar absorbing coatings are shown in the table in figure 3.

Example 5. Received a radar absorbing coating in the form of two layers of interwoven rows of aramid filaments with a 500 nm thick film of hydrogenated carbon coated with cobalt particles up to 0.05 μm in size with a cobalt content of 20 wt.% And hydrogenated carbon of 80 wt. % in the upper layer and with a cobalt content of 60 wt.% and hydrogenated carbon of 40 wt.% in the lower layer. Films were obtained by magnetron sputtering of graphite and cobalt targets in an argon-hydrogen working medium at a pressure of 5 mTorr, with an argon content of 80 wt.% And hydrogen of 20 wt.%, With an ion current density of 10 ^-2 A / cm ² , a film growth rate of 5 nm / min and with a ratio of carbon and cobalt flows of 1: 1. The rows of threads in the upper layer made an angle of φ = 55 ° with the rows of threads in the lower layer. The layers were bonded with a rubber compound adhesive. The measurement results of the reflection coefficient (R), the range of absorption frequencies, thickness and weight of the resulting radar absorbing coatings are shown in the table in figure 3.

Example 6. Received a radar absorbing coating in the form of two layers of interwoven rows of aramid filaments with a 500 nm thick film of hydrogenated carbon coated with cobalt particles up to 0.05 μm in size with a cobalt content of 20 wt.% And hydrogenated carbon of 80 wt. % in the upper layer and with a cobalt content of 60 wt.% and hydrogenated carbon of 40 wt.% in the lower layer. Films were obtained by magnetron sputtering of graphite and cobalt targets in an argon-hydrogen working medium at a pressure of 5 mTorr, at .. Ar holding 80 wt% and 20 wt% of hydrogen, at an ion current density of 10 ^-2 A / cm ^2, the film growth rate of 5 nm / min and a flow ratio of carbon and cobalt 1: 1. The rows of threads in the upper layer made an angle of φ = 125 ° with the rows of threads in the lower layer. The layers were bonded with a rubber compound adhesive. The measurement results of the reflection coefficient (R), the range of absorption frequencies, thickness and weight of the resulting radar absorbing coatings are shown in the table in figure 3.

Example 7. Received a radar absorbing coating in the form of two layers of interwoven rows of aramid filaments with a 500 nm thick film of hydrogenated carbon coated with cobalt particles up to 0.05 μm in size with a cobalt content of 20 wt.% And hydrogenated carbon of 80 wt. % in the upper layer and with a cobalt content of 60 wt.% and hydrogenated carbon of 40 wt.% in the lower layer. Films were obtained by magnetron sputtering of graphite and cobalt targets in an argon-hydrogen working medium at a pressure of 5 mTorr, with an argon content of 80 wt.% And hydrogen of 20 wt.%, With an ion current density of 10 ^-2 A / cm ² , a film growth rate of 5 nm / min and with a ratio of carbon and cobalt flows of 1: 1. The rows of threads in the upper layer made an angle of φ = 60 ° with the rows of threads in the lower layer. The layers were bonded with a rubber compound adhesive. The measurement results of the reflection coefficient (R), the range of absorption frequencies, thickness and weight of the resulting radar absorbing coatings are shown in the table in figure 3.

Example 8. Received a radar absorbing coating in the form of two layers of interwoven rows of aramid filaments with a 500 nm thick film of hydrogenated carbon coated with cobalt particles up to 0.05 μm in size with a cobalt content of 20 wt.% And hydrogenated carbon of 80 wt. % in the upper layer and with a cobalt content of 60 wt.% and hydrogenated carbon of 40 wt.% in the lower layer. Films were obtained by magnetron sputtering of graphite and cobalt targets in an argon-hydrogen working medium at a pressure of 5 mTorr, with an argon content of 80 wt.% And hydrogen of 20 wt.%, With an ion current density of 10 ^-2 A / cm ² , a film growth rate of 5 nm / min and with a ratio of carbon and cobalt flows of 1: 1. The rows of threads in the upper layer made an angle of φ = 90 ° with the rows of threads in the lower layer. The layers were bonded with a rubber compound adhesive. The measurement results of the reflection coefficient (R), the range of absorption frequencies, thickness and weight of the resulting radar absorbing coatings are shown in the table in figure 3.

Example 9. Received a radar absorbing coating in the form of two layers of interwoven rows of aramid filaments with a 500 nm thick film of hydrogenated carbon coated with cobalt particles up to 0.05 μm in size with a cobalt content of 20 wt.% And hydrogenated carbon of 80 wt. % in the upper layer and with a cobalt content of 60 wt.% and hydrogenated carbon of 40 wt.% in the lower layer. Films were obtained by magnetron sputtering of graphite and cobalt targets in an argon-hydrogen working medium at a pressure of 5 mTorr, with an argon content of 80 wt.% And hydrogen of 20 wt.%, With an ion current density of 10 ^-2 A / cm ² , a film growth rate of 5 nm / min and with a ratio of carbon and cobalt flows of 1: 1. The rows of threads in the upper layer made an angle of φ = 120 ° with the rows of threads in the lower layer. The layers were bonded with a rubber compound adhesive. The measurement results of the reflection coefficient (R), the range of absorption frequencies, thickness and weight of the resulting radar absorbing coatings are shown in the table in figure 3.

Example 10. Under the same conditions as in Example 1, a radar absorbing coating was obtained in the form of four layers of interwoven rows of glass fiber filaments coated with a 700 nm thick film of hydrogenated carbon with nickel particles embedded in it up to 0.05 μm in size. The upper layer contained 20 wt.% Nickel particles and 80 wt.% Hydrogenated carbon, the second layer contained 35 wt.% Nickel particles and 65 wt.% Hydrogenated carbon. The third layer contained particles of nickel 45 wt.% And hydrogenated carbon 55 wt.%, And the fourth (lower) layer contained particles of nickel 60 wt.% And hydrogenated carbon 40 wt.%. The rows of threads in each layer made an angle of φ = 60 ° with the rows of threads of the adjacent layer. The layers were bonded with an epoxy-based adhesive. The measurement results of the reflection coefficient (R), the range of absorption frequencies, thickness and weight of the resulting radar absorbing coatings are shown in the table in figure 3.

Example 11. Under the same conditions as in Example 1, a radar absorbing coating was obtained in the form of four layers of interwoven rows of glass fiber filaments coated with a 700 nm thick film of hydrogenated carbon with nickel particles embedded in it up to 0.05 μm in size. The upper layer contained 20 wt.% Nickel particles and 80 wt.% Hydrogenated carbon, the second layer contained 35 wt.% Nickel particles and 65 wt.% Hydrogenated carbon. The third layer contained particles of nickel 45 wt.% And hydrogenated carbon 55 wt.%, And the fourth (lower) layer contained particles of nickel 60 wt.% And hydrogenated carbon 40 wt.%. The rows of threads in each layer made an angle of φ = 90 ° with the rows of threads of the adjacent layer. The layers were bonded with an epoxy-based adhesive. The measurement results of the reflection coefficient (R), the range of absorption frequencies, thickness and weight of the resulting radar absorbing coatings are shown in the table in figure 3.

Example 12. Under the same conditions as in Example 1, a radar absorbing coating was obtained in the form of four layers of interwoven rows of fiberglass yarns coated with a 700 nm thick film of hydrogenated carbon with nickel particles embedded in it up to 0.05 μm in size. The upper layer contained 20 wt.% Nickel particles and 80 wt.% Hydrogenated carbon, the second layer contained 35 wt.% Nickel particles and 65 wt.% Hydrogenated carbon. The third layer contained particles of nickel 45 wt.% And hydrogenated carbon 55 wt.%, And the fourth (lower) layer contained particles of nickel 60 wt.% And hydrogenated carbon 40 wt.%. The rows of threads in each layer made an angle of φ = 120 ° with the rows of threads of the adjacent layer. The layers were bonded with an epoxy-based adhesive. The measurement results of the reflection coefficient (R), the range of absorption frequencies, thickness and weight of the resulting radar absorbing coatings are shown in the table in figure 3.

Example 13. Under the same conditions as in Example 1, a radar absorbing coating was obtained in the form of four layers of interwoven rows of glass fiber filaments with a 1500 nm thick film of hydrogenated carbon coated with nickel particles embedded in it with nickel particles up to 0.05 μm in size. The upper layer contained 20 wt.% Nickel particles and 80 wt.% Hydrogenated carbon, the second layer contained 35 wt.% Nickel particles and 65 wt.% Hydrogenated carbon. The third layer contained particles of nickel 45 wt.% And hydrogenated carbon 55 wt.%, And the fourth (lower) layer contained particles of nickel 86 wt.% And hydrogenated carbon 14 wt.%. The rows of threads in each layer made an angle of φ = 55 ° with the rows of threads of the adjacent layer. The layers were bonded with an epoxy-based adhesive. The measurement results of the reflection coefficient (R), the range of absorption frequencies, thickness and weight of the resulting radar absorbing coatings are shown in the table in figure 3.

Example 14. Under the same conditions as in Example 1, a radar absorbing coating was obtained in the form of four layers of interwoven rows of glass fiber filaments with a 1500 nm thick film of hydrogenated carbon coated with nickel particles embedded in it with nickel particles up to 0.05 μm in size. The upper layer contained 20 wt.% Nickel particles and 80 wt.% Hydrogenated carbon, the second layer contained 35 wt.% Nickel particles and 65 wt.% Hydrogenated carbon. The third layer contained particles of nickel 45 wt.% And hydrogenated carbon 55 wt.%, And the fourth (lower) layer contained particles of nickel 60 wt.% And hydrogenated carbon 40 wt.%. The rows of threads in each layer made an angle of φ = 125 ° with the rows of threads of the adjacent layer. The layers were bonded with an epoxy-based adhesive. The measurement results of the reflection coefficient (R), the range of absorption frequencies, thickness and weight of the resulting radar absorbing coatings are shown in the table in figure 3.

From the above examples it follows.

- in the manufacture of radar absorbing coatings with a content of particles of ferromagnetic material of less than 5 wt.% in the film of hydrogenated carbon on the outer layer of the rows of interwoven threads and more than 85 wt.% in the film, applied to the layer of rows of interwoven threads adjacent to the surface to be protected, the properties deteriorate radar absorbing coating, in particular, a decrease in the absolute value of the reflection coefficient | (R) | below the minimum acceptable value (10 dB) and narrowing the frequency range of the radio absorption.

- in the manufacture of radar absorbing coatings with the direction of the rows of threads of the adjacent layer at an angle of less than 60 ° and greater than 120 °, the properties of the radar absorbing coating are deteriorated, in particular, the absolute value of the reflection coefficient | (R) | below the minimum acceptable value (10 dB) and narrowing the frequency range of the radio absorption.

Thus, the claimed radar absorbing coating is an effective absorbing microwave radiation material at frequencies greater than 5 GHz.

Claims (8)

1. A radar absorbing coating, comprising a base of at least two layers of interwoven rows of threads bonded with a translucent material, with a hydrogenated carbon film deposited on each layer with particles of ferromagnetic material embedded in it, with the direction of the interwoven rows of threads of one layer of woven material makes an angle of 60-120 ° with the direction of the interlaced rows of filaments of the adjacent layer, and the content of particles of the ferromagnetic material is from 5 wt.% in the film deposited on and the outer layer of interwoven rows of threads, up to 85 wt.% in a film deposited on a layer of interwoven rows of threads adjacent to the surface to be protected. 2. Radar absorbing coating according to claim 1, characterized in that the layers
interwoven rows of threads are made in the form of a woven fabric. 3. The radar absorbing coating according to claim 1, characterized in that the filament
made of aramid fibers. 4. The radar absorbing coating according to claim 1, characterized in that the filament
made of fiberglass. 5. Radar absorbing coating according to claim 1, characterized in that the said film is deposited on one side of each layer of interwoven rows of threads. 6. The radar absorbing coating according to claim 1, characterized in that said film is deposited on two sides of each layer of interwoven yarns. 7. The radar absorbing coating according to claim 1, characterized in that a metal selected from the group consisting of cobalt, nickel, iron, samarium, their alloys, barium ferrite doped with rare earth elements, nickel-zinc ferrite with a titanium additive is introduced as a ferromagnetic material; manganese-zinc ferrite with a titanium additive. 8. The radar absorbing coating according to claim 1, characterized in that an adhesive composition based on a rubber or epoxy mixture is introduced as a radiolucent material.

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