RU178702U1 - Fractron Fractal Reflective Screen - Google Patents

Abstract

The utility model relates to the field of radio engineering, and more specifically to reflective screens for passive radar reflectors and reflectors. The lattice elements of the reflective screen of the fractal structure have a hierarchical morphology, which demonstrates the properties of self-similarity on different scales and therefore considered as a fractal formation, includes alternating layers with different electrical characteristics. The first layer contains a semiconductor material. The next layer is the material, which is a hierarchically constructed composite, which also includes a layered structure consisting of a semiconductor and a hierarchically constructed composite, the structure of which is similar to the whole object. The minimum size of the fractal structure composite layer is the radius of the van der Waals chemical element of which the composite is composed. It is well known that when exposed to electromagnetic radiation on nanostructures, changes in the electrophysical properties of the material occur. The fractal structure of the composite allows to obtain unique electrical characteristics, which are difficult to obtain with traditional methods of forming the material. The fractal structure of the elements of the reflective screen allows you to increase the operating frequency range by an average of 5 GHz, compared with the known reflective screens with a grid of a traditional structure. By changing the level of fractality, it becomes possible to control the maxima of the reflection coefficient. 3 ill.

Description

The utility model relates to the field of radio engineering, and more specifically to reflective screens for passive radar reflectors and reflectors, and can be used as an element of innovative antenna designs, broadband and nonlinear radar devices, localization tools and mobile objects, selective and absorbing materials, and also intelligent applications in the field of information security.

Known reflective screen for mirror antennas, made in the form of a paraboloid of revolution of solid metal (see, for example, AS USSR No. 1646017 in class H01Q 15/16, publ. 04/30/1991).

Known reflective screen made in the form of a plate of solid metal (see, for example, AS USSR No. 1332422, according to class IPC H01Q 15/18, publ. 23.02.1991). Such a screen is used in passive radar corner reflectors and corner antennas.

A common disadvantage of these reflective screens is the large mass, as they are made of solid metal. In addition, they have great aerodynamic drag.

These shortcomings were not found in reflective screens made in the form of one thin conductive perforated plate (see, for example, Aizenberg G.Z. Yampolsky V.G., Tereshin ON, Antennas for VHF. Part 2 - M .: “Communication ". - 1977. - S. 154), or in the form of a system of parallel thin metal plates whose planes are parallel to the direction of wave propagation and perpendicular to the electric field vector (see AS No. 1732800 according to class IPC H01Q 15/14). The plates are located at a distance from each other less than half the wavelength of the working frequency range.

The disadvantage of these screens is that part of the power of the electromagnetic wave seeps through them.

Closest to the claimed is a reflective screen containing a lattice of metal conductors (see RF patent No.RU 32323 Ul H01Q 15/14 publ. 09/10/2003; Bilenko D.I., Lodgauz V.A., Terin D.V.) With an appropriate choice of lattice parameters — the diameter of the conductors and its period relative to the radiation wavelength — the device reflects a large part of the electromagnetic wave power. The mass of such a screen is several orders of magnitude lower than the mass of a screen made of solid metal. Aerodynamic drag is also reduced compared to the drag of a solid metal screen.

The disadvantage of this screen is the increase in the leakage through it of part of the power, which reduces its reflection coefficient. When used as a reflector of mirror antennas, the efficiency is reduced and the antenna pattern is distorted. There is no way to control the reflection maxima by changing the thickness of the lattice elements.

The objective of this utility model is to increase the reflection coefficient in a wide frequency range and to develop the ability to control the reflection maximums by changing geometric characteristics, as well as increasing the efficiency.

The technical result is achieved by changing the design of the lattice, each element of the lattice is a multilayer hierarchically built composite consisting of metal and a semiconductor, having a self-similar structure and considered as a fractal formation, as well as by increasing the reflection coefficient in a wide frequency range and developing features control of reflection maxima due to changes in geometric characteristics.

In this case, the lattice element of the reflecting screen, which includes alternating layers (metal / semiconductor) with different electrical characteristics, is primarily distinguished by the fact that it has a hierarchical morphology that demonstrates self-similarity properties at different scales, the minimum width of the element of the fractal structure composite layer can reach a size equal to the radius of van der Waals chemical element of which the composite consists.

The period of the gratings, the distance between the gratings, the length and width of the grating element is selected from the condition:

where b is the lattice period; n, m, p is the length, width and height of the lattice element, d is the distance between the lattice elements, f _max is the maximum frequency of the working frequency range of the screen, and s is the speed of light in vacuum.

The screen when used in corner radar reflectors and in corner antennas is made on the basis of gratings similar to each other.

The essence of the utility model is illustrated by drawings, where in FIG. 1 shows a reflective screen for corner radar reflectors and corner antennas, FIG. 2 - a lattice element of a reflective screen of a fractal structure, FIG. 3 - frequency dependence of the refractive index at different levels of fractality of the lattice element.

The reflecting screen of the fractal structure "Fraxton" is made in the form of a lattice. The lattice elements of a reflective screen have a layered hierarchically structured structure similar to a fractal formation consisting of metal and a semiconductor.

The total number of lattice elements is selected from the condition:

L is the width of the grating, F is the focus of the reflector.

The period of the gratings, the distance between the gratings, the length and width of the grating element is selected from the condition:

where b is the lattice period; n, m, p is the length, width and height of the lattice element, d is the distance between the lattice elements, f _max is the maximum frequency of the working frequency range of the screen, and s is the speed of light in vacuum.

The reflection coefficient R of the screen was calculated as follows. The values of the reflection coefficient R for a semi-infinite medium is determined from the relation (see, for example, M. Born, E. Wolf. Fundamentals of optics. - M., Science - 1970):

where n and κ are the refractive indices and absorption of the medium, respectively.

The indices of refraction and absorption included in expression (1), as shown by the electrodynamic calculation, satisfy the following relationships:

In FIG. Figure 3 shows a graph of the dependence of the reflection index on the wave frequency of external electromagnetic radiation and the level of fractality of the grating element i (1-i = 10, 2-i = 6, 3-i = 3), corresponding to the following parameters of the reflecting screen:

1-b = d = 0.5 cm; m = n = p = 0.5 cm;

2-b = d = 0.5 cm; m = n = p = 0.045 cm;

3-b = d = 0.5 cm; m = n = p = 10 ^-2 cm;

p = iΔ

The proposed device operates as follows. The radiation falls on a reflective screen. With the parameters indicated above, the reflection coefficient at f≤f _max R≥0.99999. As can be seen from FIG. 3, the operating frequency range depends on the level of fractality of the lattice element of the reflecting screen. The fractal structure of the elements of the reflective screen allows you to increase the operating frequency range by an average of 5 GHz, compared with the known reflective screens with a grid of a traditional structure. By changing the level of fractality, it becomes possible to control the maxima of the reflection coefficient. If the proposed reflective screen is made with the parameters described above, then the efficiency of such a reflective screen, compared to reflective screens with a grid of a traditional structure, increases by 5.5%.

Claims (3)

The reflective screen of the fractal structure made in the form of a lattice, characterized in that the lattice elements of the reflective screen have a layered hierarchically structured structure similar to a fractal formation consisting of metal and a semiconductor, the period of the gratings, the distance between the gratings and the width of the regatta element are selected from the condition:

where b is the lattice period; n, m, p is the length, width and height of the lattice element, d is the distance between the lattice elements, ƒ _max is the maximum frequency of the working frequency range of the screen, and s is the speed of light in vacuum.

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