KR102570467B1 - Isotropic electromagnetic wave scatterer and launch vessel including the same - Google Patents

Abstract

The present application relates to an isotropic radio wave scatterer and a projectile including the same.

Description

Isotropic radio wave scattering body and projectile including the same

The present application relates to an isotropic radio wave scatterer and a projectile including the same.

A conventional radio wave scattering body has an effective scattering cross-sectional area only for polarized electromagnetic waves parallel to the direction of its structure. Accordingly, the conventional radio wave scattering object can be identified by a radar using various polarizations, and the effectiveness of the conventional radio wave scattering object is greatly reduced.

Specifically, the conventional radio wave scattering body has a high effective scattering cross-sectional area only for electromagnetic waves in a direction parallel to the structure, and shows an effective scattering cross-sectional area converging to zero for electromagnetic waves having polarization in a direction perpendicular to the structure. In addition, it has a needle-shaped structure, and after a certain period of time during scattering, it is aligned with the sea level by laminar flow, and the scattering characteristics appearing in the spatial average depend greatly on the polarization of the electromagnetic wave.

In order to solve the above problem, a corner reflector using retroreflection is used as a radio wave scattering body having no polarization dependence. The corner reflector has a high directivity of electromagnetic wave scattering due to the nature of retroreflection and has a large effective scattering cross-sectional area with respect to the radio wave incident direction, but has a disadvantage in that the volume of the scattering body becomes very large. As the size of the structure increases, the effective scattering cross-sectional area increases in proportion to the fourth power of the radius, but there is a problem in that sensitivity to angle errors also increases.

Mianroodi, R. Y., Heidar, H., & Armaki, H. M. (2016). Expandable shipboard decoy including adequate RCS by using trihedral corner reflectors. IET Science, Measurement & Technology, 10(5), 485-491.

An object of the present application is to provide an isotropic radio wave scatterer and a projectile including the same.

However, the problem to be solved by the present application is not limited to the above-mentioned problem, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

According to a first aspect of the present invention, an isotropic radio wave scattering body having an isotropic symmetric structure in which four or more branches are connected to a central point, the angles formed by two adjacent branches are all the same, and the lengths of the branches are all the same. to provide.

A second aspect of the present application provides a projectile comprising the isotropic radio wave scattering body according to the first aspect of the present application.

Since the structure of the isotropic radio wave scatterer according to the embodiments of the present invention uses electromagnetic wave resonance, the same structure can be manufactured in different sizes to freely select a target scattering frequency band, and accordingly, the resonance frequency at which the maximum value of the scattering cross section appears You can choose.

Isotropic radio wave scatterers according to embodiments of the present disclosure have mechanical isotropy and electromagnetic quasi-isotropy, and may not be identified by a radar capable of identifying polarization dependence. The isotropic radio wave scattering body according to embodiments of the present disclosure may be capable of isotropic scattering having no dependence on the polarization of an incident electromagnetic wave through a symmetrical structure. The isotropic radio wave scatterer according to embodiments of the present invention may implement scattering characteristics without polarization dependence in spatial average by using a mechanically isotropic structure that is not aligned in a specific direction by an external influence such as laminar flow.

The isotropic radio wave scatterer according to the embodiments of the present application can replace the conventional radio wave scatterer without changing the conventional launch system (in particular, the launch system used in the conventional needle-shaped resonant radio wave scatterer), so it can be commercialized. can be easily

The manufacturing process of the isotropic radio wave scattering body according to embodiments of the present disclosure is low and economical.

FIG. 1 is a three-dimensional view of an unfolded form of an isotropic radio wave scattering body having a tetrahedral structure according to an embodiment of the present disclosure.
FIG. 2 is a plan view showing an isotropic radio wave scattering body having the same structure as that of FIG. 1 in the axial direction.
FIG. 3 is a plan view showing an isotropic radio wave scattering body having the same structure as that of FIG. 1 in a different axis direction.
4A to 4D are results obtained by calculating a scattering cross-sectional area calculated according to an electromagnetic wave incident direction of an isotropic radio wave scatterer having a tetrahedral structure according to an embodiment of the present application using a finite difference time domain (FDTD) simulation. As a graph, FIGS. 4A to 4C are graphs of results when θ = 18.25 °, θ = 36.5 °, and θ = 54.75 °, respectively, and FIG. 4D is a graph in which the experimental results of FIGS. 4A to 4C are merged.
5 is a graph of a result of calculating the scattering cross-sectional area of a conventional radio wave scatterer using finite-difference time-domain simulation.
6 is a diagram illustrating an isotropic radio wave scattering body having six branches according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, embodiments and embodiments of the present application will be described in detail so that those skilled in the art can easily practice the present invention. However, the present disclosure may be embodied in many different forms and is not limited to the implementations and examples described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Throughout this specification, when a part is said to be "connected" to another part, this includes not only the case of being "directly connected" but also the case of being "electrically connected" with another element in between. do.

Throughout the present specification, when a member is said to be located “on” another member, this includes not only a case where a member is in contact with another member, but also a case where another member exists between the two members.

Throughout the present specification, when a certain component is said to "include", it means that it may further include other components without excluding other components unless otherwise stated.

As used herein, the terms "about," "substantially," and the like are used at or approximating that number when manufacturing and material tolerances inherent in the stated meaning are given, and are intended to assist in the understanding of this disclosure. Accurate or absolute figures are used to prevent undue exploitation by unscrupulous infringers of the stated disclosure.

The term "step of" or "step of" used throughout the present specification does not mean "step for".

Throughout this specification, the term "combination(s) of these" included in the expression of the Markush form means one or more mixtures or combinations selected from the group consisting of the components described in the expression of the Markush form, It means including one or more selected from the group consisting of the above components.

Throughout this specification, reference to "A and/or B" means "A or B, or A and B".

Hereinafter, embodiments of the present application have been described in detail, but the present application may not be limited thereto.

A first aspect of the present invention is an isotropic radio wave scattering body having an isotropic symmetric structure in which four or more branches are connected to a central point, wherein the angles formed by two neighboring branches are all the same, or in the isotropic symmetric structure, the branches An isotropic radio wave scattering body within a range of increasing or decreasing within about 10% of an angle determined by the number, all of the branches having the same length, or within a range of increasing or decreasing within about 10% of the length of the branches. .

In one embodiment of the present application, the isotropic symmetric structure is a regular polyhedron, which may be a regular tetrahedron, a regular hexahedron, a regular octahedron, a regular dodecahedron, or a regular icosahedron, or a form in which four or more points on a spherical surface connected to a central point are connected.

In one embodiment of the present application, it is said that the isotropic It may mean a range appropriately changed according to the target resonant frequency of the radio wave scattering body. For example, when the isotropic radio wave scattering body includes four branches and forms a tetrahedral structure, the angle formed by the two neighboring branches may be a value between about 100° and about 120°, but is not limited thereto. can In addition, for example, when the isotropic radio wave scattering body includes six branches and forms a regular octahedral structure, an angle formed by two adjacent branches may be a value between about 80° and about 100°, but is limited thereto. It may not be.

In one embodiment of the present application, in the isotropic symmetric structure, the range in which the length of the branch increases or decreases within 10% of the length of the branch means a range that is appropriately changed according to the target resonant frequency of the isotropic radio wave scattering body. it may be For example, when any one branch of the isotropic radio wave scattering body is about 7 mm long, the length of the other branch may be between about 6 mm and about 8 mm, or between about 6.3 mm and about 7.7 mm. However, it may not be limited thereto.

In one embodiment of the present application, when the isotropic symmetric structure is a regular polyhedron, the isotropic radio wave scattering body may have a shape in which the center point is located at the center of gravity and a branch connected to the center point connects the center point and the vertex of the regular polyhedron. . Accordingly, the isotropic radio wave scattering body according to an exemplary embodiment of the present disclosure may achieve mechanical isotropy. In addition, the structure of the isotropic radio wave scatterer according to an embodiment of the present application has a small difference in scattering cross-sectional area due to the direction of the incident electromagnetic wave, except for the anisotropy caused by the finite speed of the electromagnetic wave. In addition, it shows the same scattering cross-sectional area for electromagnetic waves having different polarizations incident from the same direction. Accordingly, the isotropic radio wave scattering body according to an exemplary embodiment of the present disclosure can resolve electromagnetic anisotropy and achieve electromagnetic quasi-isotropy. When one or more isotropic radio wave scatterers are scattered according to an embodiment of the present application, they are randomly arranged in a target space to form a scatterer cloud and exhibit constant scattering characteristics regardless of the incident direction and electromagnetic wave polarization direction in the spatial average. can Here, the scattering cross-sectional area is a value obtained by dividing the power (W) of electromagnetic waves scattered by an object by the electromagnetic wave power density (W/m ² ) incident on an object, and is a value that can evaluate the scattering characteristics of an antenna or radio wave scattering body. am. The scattering cross-sectional area can be greatly improved compared to the actual cross-sectional area of the scattering object by using the resonance phenomenon, and it is advantageous to have a large scattering cross-sectional area compared to the volume/mass of the scattering object for efficient radar deception.

In one embodiment of the present application, the branch may be made of a conductive material layer. The conductive material may be a metal, shape memory alloy, conductive polymer, conductive ceramic, or conductive carbon allotrope. For example, the metal may be one or more selected from Al, Cu, Au, Ag, Be, Rh, W, Zn, Ni, Fe, Pt, Sn, and alloys thereof.

In one embodiment of the present application, the conductive material layer may be thicker than a minimum thickness (several micrometers) capable of reflecting RF electromagnetic waves.

In one embodiment of the present application, the core of the branch may be hollow or made of carbon fiber or polymer. Here, the polymer is polyethyleneterephthalate (PET), polyimide (PI), polypropylene (PP), polyethylene (PE), polyester (polyester), polycarbonate (PC) , poly-methylmethacrylate (PMMA), polyurethane (PU), polyvinyl chloride (PVC), ethylene-vinyl acetate copolymer (EVA), polyvinyl It may be one or more selected from alcohol (poly vinyl alcohol; PVA), nylon, cellulose, glass fiber, and polylactic acid (polylactic acid, PLA). Here, the radius of the core may be one that does not affect the scattering characteristics of the isotropic radio wave scattering body, but is not limited thereto.

In one embodiment of the present application, one or more of the branches may be coated with a dielectric layer. In one embodiment of the present application, all of the branches may be coated with a dielectric layer. The dielectric layer may be coated on the conductive material layer to protect the conductive material layer or generate an electrostatic repulsive force. The electrostatic repulsive force may be generated by friction during spreading, and may play a role in realizing an isotropic structure.

In one embodiment of the present application, the dielectric layer may be coated with one type of dielectric material on all the branches. The dielectric material is not particularly limited as long as it is an insulator having a charge on its surface in an electric field, and may be glass, rubber, plastic, ceramic, or silicon as non-limiting examples.

In one embodiment of the present application, the dielectric layer may be coated with two or more types of dielectric materials having different charge sequences on each of the branches. For example, when a part and the rest of the branches are coated with two types of dielectric materials having different electrification lines, electromagnetic repulsive force can be more easily generated.

Referring to FIG. 1 , a tetrahedral structure among isotropic radio wave scatterers according to embodiments of the present disclosure can be described as an example. The tetrahedral structure of the isotropic radio wave scatterer 100 may include four branches 101, 102, 103, and 104, and the angle between the branches may be about 109.5°. The four branches may be basically formed of conductive material layers 101, 102, 103, and 104. The branch core 203 may be empty and made of only a conductive material layer. The core 203 may be filled with a material that is lighter than the conductive material layer, and the type of material is not particularly limited. In addition, the outside of the conductive material layer may be coated with a dielectric layer 303 . Here, essential components of the isotropic radio wave scattering body 100 are the conductive material layers 101, 102, 103, and 104, and the core and dielectric layers may be optional components.

In one embodiment of the present application, the length of the branch may be about 1/8 to about 3/8 of the target resonant frequency, but may not be limited thereto. In one embodiment of the present application, the length of the branch may be about 1/4 to about 1/2 of the target resonant frequency.

In one embodiment of the present application, the diameter of the cross section of the branch may be about 5 μm to about 500 μm, but may not be limited thereto. For example, the diameter of the cross section of the branch is about 5 μm to about 500 μm, about 5 μm to about 400 μm, about 5 μm to about 300 μm, about 5 μm to about 200 μm, about 10 μm to about 500 μm , about 10 μm to about 400 μm, about 10 μm to about 300 μm, about 10 μm to about 200 μm, about 50 μm to about 500 μm, about 50 μm to about 400 μm, about 50 μm to about 300 μm, about 50 μm to about 200 μm, about 100 μm to about 500 μm, about 100 μm to about 400 μm, about 100 μm to about 300 μm, or about 100 μm to about 200 μm.

In one embodiment of the present application, the isotropic radio wave scattering body may have an isotropic symmetric structure due to the electromagnetic repulsive force of the branches, or may have an isotropic symmetric structure because the branches include a shape memory alloy or an elastic material. there is.

In one embodiment of the present application, the isotropically symmetrical structure may be implemented in a manner in which the branches are charged through friction generated during the scattering of the isotropic radio wave scattering body. When the isotropic radio wave scattering body is charged, the branches spread out in a form that minimizes the repulsive force between neighboring branches. Therefore, the isotropic radio wave scattering body forms an isotropic structure (eg, a shape in which the vertex of a regular tetrahedron is connected to the center of gravity) by the balance of the electromagnetic repulsive force. In another embodiment of the present application, a method of implementing an isotropic structure by configuring the isotropic radio wave scattering body with a shape memory alloy. Here, before launch, the isotropic radio wave scattering body is deformed into a multi-layered needle shape and stored in the projectile, and the shape memory alloy is naturally spread into a three-dimensional structure by heat generated during dispersion. In another embodiment of the present application, a material having high elasticity is used as a core of the isotropic radio wave scattering material, stored in a dense form, and returned to an unfolded form by restoring force during dispersion.

A second aspect of the present application provides a projectile comprising the isotropic radio wave scattering body according to the first aspect.

Detailed descriptions of portions overlapping with the first aspect of the present application have been omitted, but the description of the first aspect of the present application can be equally applied even if the description is omitted in the second aspect of the present application.

In one embodiment of the present application, the center point of the isotropic radio wave scattering body may have flexibility and gather the branches in one direction to mount the isotropic radio wave scattering body.

Hereinafter, the present application will be described in more detail using examples, but the following examples are only illustrative to aid understanding of the present application, and the content of the present application is not limited to the following examples.

[Example]

1. Specification of tetrahedral structure isotropic radio wave scatterer (Example)

- Branch structure: cylinder shape with hollow inner core and no dielectric coating

- Properties of branch: metal with electrical conductivity at the level of aluminum

- Length of single branch: 7.5 mm 　 (1/4 of the target frequency 10 GHz wavelength)

- Diameter of cross section of branch: 0.15 mm (150 μm)

2. FDTD Simulation for the Example

,

로 줄일 수 있었다. 시뮬레이션 결과, 동일한 θ 에서 다른 α를 가지는 경우에도 일정한 산란 단면적을 나타낸다 (도 4). 이를 통하여 실시예 1에 따른 등방성 전파 산란체는 전자기적 준등방성을 나타냄을 확인할 수 있다.Based on the above embodiment, the scattering cross-sectional area was calculated according to the electromagnetic wave incident direction, and the angle α formed by the x-axis and the straight line connecting the xy plane projection point and the origin in the spherical coordinate system has a different value for a given θ It shows the scattering cross section of the isotropic radio wave scatterer that appears. By using the fact that each branch is equal due to the symmetry of the structure, the electromagnetic wave incident direction ( θ , α ) to be searched is

,

could be reduced to As a result of the simulation, even when the same θ has different α, a constant scattering cross section is shown (FIG. 4). Through this, it can be confirmed that the isotropic radio wave scattering body according to Example 1 exhibits electromagnetic quasi-isotropy.

3. FDTD simulation for a conventional radio wave scatterer (comparative example)

The conventional needle-shaped dipole resonance radio wave scatterer and the FDTD simulation according to the present invention were compared.

) According to FIG. 5, the deviation of the scattering cross-section at the resonant frequency according to θ is about 20% at most. This can be seen as a difference caused by the finite speed of electromagnetic waves. That is, the scattering cross-sectional area of the conventional radio wave scattering body shows a large dependence on the electric field constituting the electromagnetic wave and the angle α formed by the scattering body. (

)

The above description of the present application is for illustrative purposes, and those skilled in the art will understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present application. Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as distributed may also be implemented in a combined form.

The scope of the present application is indicated by the following claims rather than the detailed description above, and all changes or modifications derived from the meaning and scope of the claims and equivalent concepts thereof should be construed as being included in the scope of the present application. .

100: isotropic radio wave scatterer
101, 102, 103, 104: branch or conductive material layer
203: core
303 dielectric layer

Claims (11)

An isotropic radio wave scatterer having an isotropic symmetric structure in which four or more branches are connected to a central point,
The angles formed by the two adjacent branches are all the same, or are increased or decreased within 10% of the angle determined by the number of branches in the isotropic symmetric structure,
The lengths of the branches are all the same, or are within the range of increasing or decreasing within 10% of the length of the branches,
have an isotropic symmetric structure due to the electromagnetic repulsive force of the branches, or
The branches having an isotropic symmetric structure by including a shape memory alloy or an elastic material,
Isotropic radio wave scatterer. According to claim 1,
The isotropic radio wave scattering body, wherein the isotropic symmetric structure is in the form of connecting four or more points on a regular tetrahedron, regular hexahedron, regular octahedron, regular dodecahedron, regular icosahedron, or spherical surface with a central point. According to claim 1,
The isotropic radio wave scatterer, wherein the branches are made of a conductive material layer. According to claim 1,
The core of the branch may be hollow; or an isotropic radio wave scatterer made of carbon fiber or polymer. According to claim 1,
An isotropic radio wave scatterer, wherein at least one of the branches is coated with a dielectric layer. According to claim 5,
The isotropic radio wave scattering material, wherein the dielectric layer is coated with one type of dielectric material on all the branches, or two or more types of dielectric materials having different charge sequences on each of the branches. According to claim 1,
The isotropic radio wave scattering body, wherein the length of the branch is 1/8 to 3/8 of the target resonant frequency. According to claim 1,
The isotropic radio wave scatterer, wherein the diameter of the cross section of the branch is 5 μm to 500 μm. delete A projectile comprising the isotropic radio wave scatterer according to any one of claims 1 to 8. According to claim 10,
The projectile, wherein a central point of the isotropic radio wave scattering body has flexibility and collects the branches in one direction to mount the isotropic radio wave scattering body.