RU226275U1 - Broadband electromagnetic radiation absorber - Google Patents

Abstract

The utility model relates to the field of radio engineering, in particular to absorbers of electromagnetic radiation, and can be used as the main and/or auxiliary means for equipping anechoic chambers and shielded rooms that ensure radio engineering measurements and testing of technical equipment for compliance with electromagnetic compatibility requirements. The technical result of the proposed utility model is the creation of a broadband electromagnetic radiation absorber with a simplified design and an extended microwave frequency range. The technical result, according to the proposed solution, is achieved due to the fact that the broadband absorber of electromagnetic radiation is a dielectric solid homogeneous panel, the front surface of which is formed by an array of wedge-shaped absorption elements in the form of a regular tetrahedral pyramid, placed on a common base in the shape of a rectangular parallelepiped. The panels are made of oil- and gasoline-resistant frost-resistant material such as silicone or oil- and gasoline-resistant frost-resistant material such as fluorosilicone, and spherical fine particles made of soft magnetic amorphous nanocrystalline alloys based on iron and cobalt are added as a filler that absorbs EM waves.

Description

The utility model relates to the field of radio engineering, in particular to absorbers of electromagnetic radiation, and can be used as the main and/or auxiliary means for equipping anechoic chambers and shielded rooms that ensure radio engineering measurements and testing of technical equipment for compliance with electromagnetic compatibility requirements.

State of the art

An ultra-wide-range absorber of electromagnetic waves for anechoic chambers and shielded rooms is known (patent RU 2453953, application 2011123746/07 dated June 14, 2011), which is a three-layer structure consisting of a dielectric material, a magnetic material and a metal substrate. The dielectric material has a flat shape in the form of wedge-shaped elements made of radio-absorbing foam glass. The magnetic material consists of plates of magnesium-zinc ferrite containing magnesium, zinc and iron oxides as a base.

The main disadvantages of this absorber include the relatively low upper operating frequency, as well as the complexity and large weight of the structure.

Also known is an electromagnetic wave absorber taken as a prototype (patent RU 2359374, application 2008118733/09 dated May 14, 2008), which is a hollow dielectric housing in the form of a tetrahedral pyramid with a base in the shape of a rectangular prism with rounded edges of the pyramidal part filled with filler. The body is made of low-flammable polymer, and low-flammable dry mixtures of highly stable components based on cellulose materials and carbon fiber are used as filler.

The main disadvantages of the absorber include the fragility of the structure and the complexity of its manufacture.

Essence of a utility model

The technical result of the proposed utility model is the creation of a broadband electromagnetic radiation absorber with a simplified design and an extended microwave frequency range.

The technical result, according to the proposed solution, is achieved due to the fact that the broadband absorber of electromagnetic radiation is a dielectric solid homogeneous panel, the front surface of which is formed by an array of wedge-shaped absorption elements in the form of a regular tetrahedral pyramid, placed on a common base in the shape of a rectangular parallelepiped. The panels are made of thermo-fire-resistant porous polyurethane foam material filled with non-falling electrically conductive carbon nano- and microparticles, the outer surfaces of which are painted with a water-repellent dispersion system.

The disadvantages of the technical solution include the relatively high value of the lower frequency of the operating range, as well as its pronounced dependence on the geometric dimensions of the absorption elements.

The main technical parameter that adequately characterizes the absorption capacity of microwave absorption materials, as well as various absorption devices based on them, is the frequency dependence of the reflection coefficient of a plane monochromatic EM wave in the HF and microwave ranges from their surface, which is mainly determined by the degree of heterogeneity media (in electromagnetic terms) at the boundary of which the EM wave is reflected and by the shape of the surface of this boundary.

To a first approximation, the degree of heterogeneity of media can be assessed by comparing the values of the wave impedances (VR) provided to a given wave as it propagates in a given medium. The lower the difference between the frequency dependences of these values, the more consistent the environments are. The frequency dependence of the BC of the absorbing material is determined by the following relationship:

, (1)

Where - complex frequency-dependent relative magnetic and dielectric constants, from the ratio of the imaginary and real parts of which, the values characterizing the magnetic and dielectric losses of the energy of an EM wave propagating in the material are calculated:

- magnetic and dielectric loss tangents.

Since in most cases, absorbing materials are designed to absorb EM waves from free air space, the airspace of which is determined by the following relationship:

, (2)

Where - magnetic and dielectric constants of vacuum,

the matching task in general comes down to “aligning” the frequency dependence of the material’s BC with the BC of free space , which is difficult to implement in practice, especially when using flat absorbers when selecting optimal values

This problem is solved relatively well by the use of volumetric wedge-shaped absorbers, in which the air force at the air-absorber interface is formed not only by the parameters of the material , but also the shape of the surface with which the wave front interacts.

The broadband absorber of electromagnetic radiation is a dielectric solid homogeneous panel, the front surface of which is formed by an array of wedge-shaped absorption elements 1 of a regular pyramidal shape, placed on a common base 2 in the shape of a rectangular parallelepiped. Moreover, to ensure optimal frequency dependence of the absorption characteristic, the value of the dihedral angle between the side faces and the base of the pyramidal absorption characteristics should be equal to 78±10°. The panels are made of thermo-fire-resistant porous polyurethane foam material filled with non-shedding electrically conductive carbon nano- and microparticles. An adhesive layer 3 is applied to the bottom surface of the base, which is necessary for fixing the absorption panels to the installation surfaces. If the absorption panel is installed on an electrically conductive surface, the adhesive layer is filled with metal microballs and/or carbon fiber particles 4, and the thickness of the adhesive layer is less than the diameter of the balls and the length of the carbon particles to ensure electrical contact of the panel with the mounting surfaces.

In addition, to reduce the absorption of moisture from the air by the absorber, a water-repellent dispersion system is applied to all its external surfaces.

The dimensions of the panel are determined by the following ratios:

, (3)

, (4)

, (5)

Where is the length of the panel, a is the size of the base of the tetrahedral pyramid, i is the number of absorption elements along the length, - panel width, j - number of absorption elements along the width, - height of the pyramids; - the value of the dihedral angle between the base and the side surfaces of the pyramids, degrees, - the height of the base, equal to 0.1...0.33 of the height of the pyramid.

Using relations (3)-(5), it is possible to calculate the optimal geometric dimensions for absorption panels with an operating frequency range from approximately 100 MHz to 50 GHz and above.

As an example, in FIG. Figure 3 shows a graph of the frequency dependence of the amplitude of the reflection coefficient of a plane normally incident EM wave from the proposed broadband absorber of electromagnetic radiation with the size of the base of the absorption element in the form of a regular tetrahedral pyramid of 50 mm and overall dimensions of 500×500×150 mm.

Brief description of drawings

In fig. Figure 1 shows a general isometric view of the absorber panel with a local section and breaks;

in fig. Fig. 2 shows an external view of A;

in fig. Figure 3 shows a graph of the frequency dependence of the amplitude of the reflection coefficient of a plane normally incident wave from a broadband absorber of electromagnetic radiation.

In fig. 1, 2 indicated:

1 - base;

2 - pyramidal absorption element;

3 - adhesive layer;

4 - metal balls (adhesive filling).

Claims (1)

A broadband electromagnetic radiation absorber containing wedge-shaped absorption elements in the shape of a regular tetrahedral pyramid with a base in the form of a rectangular parallelepiped, characterized in that solid homogeneous absorption elements placed on a common base with a height equal to one tenth to one third of the height of the absorption element, combined into a solid dielectric panel and made of thermo-fire-resistant porous polyurethane foam material, coated with a water-repellent dispersed system and filled with non-falling electrically conductive carbon microparticles, and on the bottom surface of the panel an adhesive layer filled with metal microbeads and carbon fiber particles is applied, with the side surfaces of the absorption elements and surfaces their bases form dihedral angles equal to 78±10°.