Passive adjustable RCS radar target simulation device

Abstract

The invention provides a passive adjustable RCS radar target simulation device. The passive adjustable RCS radar target simulation device comprises a Luneberg ball, a first shielding cover and a second shielding cover, the first shielding cover and the second shielding cover are each of a partial spherical shell structure, each partial spherical shell structure is provided with two symmetrical faces, one symmetrical face is semicircular, and the other symmetrical face is fan-shaped. The central angle of the sector is larger than 90 degrees and smaller than 180 degrees. The first shielding cover and the second shielding cover both surround the luneberg ball, the first shielding cover, the second shielding cover and the luneberg ball are coaxial, the coaxial axis is made to be the Z axis, the first shielding cover and the second shielding cover both can rotate around the Z axis, and the opening angle of the first shielding cover and the opening angle of the second shielding cover are adjusted. The exposed area of the luneberg ball facing the incident direction of the electromagnetic waves is adjusted, and then the incoming wave amount of the electromagnetic waves entering the luneberg ball is adjusted; the invention has the characteristics of wide working angular domain and flat and adjustable RCS output.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of radar, and relates to a passive adjustable RCS radar target simulation device. BACKGROUND

[0002] Radar Cross Section (RCS) is a physical quantity representing the ability of a target to intercept and scatter radar waves. The larger the RCS of a target, the stronger its ability to intercept incident radar waves and scatter them towards the radar receiving antenna direction, and the farther the radar detection range. A passive radar target simulation device is usually designed in terms of material, structure and shape to have ideal RCS output characteristics, has the characteristics of "small size and large RCS", and can be installed on different platforms such as aircraft, ships and vehicles to simulate the radar scattering characteristics of specific targets.

[0003] Common passive radar target simulation devices mainly include various types of two-dimensional / three-dimensional reflectors, corner reflector assemblies composed of several corner reflectors, and dragon ball lens reflectors (referred to as "dragon ball"). They reflect, transmit and concentrate incident waves, and finally reflect radar waves back along the incoming wave direction, thereby enhancing RCS. The RCS of such targets is related to their geometric feature size and radar wavelength. Once the size of the passive radar target simulation device and the radar operating frequency are given, the RCS is generally determined. For the demand of simulating different RCS levels, different size specifications of simulation devices need to be selected, which has many limitations and inconveniences in actual application. Therefore, it is of great significance to design and develop a passive adjustable RCS radar target simulation device that has a certain dynamic range of RCS output to meet the diversified use requirements of scattering levels.

[0004] In view of the above-mentioned needs, the patent "Radar target design method and device" with application number 201910006970.5 realizes strong scattering body simulation of a bistatic radar system, and cannot realize adjustable radar scattering cross section of a monostatic target. The patent "Adjustable RCS mechanism for radar target" with patent number CN113917412A designs a shielding mechanism to control the amount of radar waves entering the "mechanism" by adjusting the opening area of the shielding mechanism, thereby realizing adjustable radar scattering characteristics of the target. This method has the problem that the RCS of the target changes synchronously with the width of the scattering angle domain, especially when the RCS output of the target is small, the scattering angle domain range narrows sharply, and the demand for flat output of wide-angle RCS cannot be met. SUMMARY

[0005] The present application aims to at least solve one of the problems existing in the prior art.

[0006] To this end, the application provides a passive adjustable RCS radar target simulation device, which has the characteristics of wide working angle range and flat and adjustable RCS output.

[0007] The technical solution of the application is:

[0008] The passive adjustable RCS radar target simulation device comprises a dragon ball, a first shielding cover and a second shielding cover.

[0009] The first shielding cover and the second shielding cover are both partially spherical shell structures, each having two symmetrical surfaces, one of which is semicircular and the other of which is fan-shaped; the central angle of the fan-shaped surface is greater than 90° and less than 180°.

[0010] The first shielding cover and the second shielding cover are both arranged outside the dragon ball, and the first shielding cover, the second shielding cover and the dragon ball are coaxial, with the axis of the coaxial arrangement being the Z-axis; the first shielding cover and the second shielding cover can rotate around the Z-axis; by adjusting the opening angle of the first shielding cover and the second shielding cover, the exposed area of the dragon ball facing the direction of electromagnetic wave incidence can be adjusted, so that the amount of incoming electromagnetic waves into the dragon ball can be adjusted.

[0011] Further, the first shielding cover is formed by two regions, one of which is an electromagnetic shielding region A and the other of which is an electromagnetic wave transmission region A; the electromagnetic wave transmission region A is the region formed by the intersection of the spherical shell and the cone with the apex at the center of the first shielding cover, the center line being the Z-axis and the included angle between the generatrix and the center line being 30°; the rest of the region except the electromagnetic wave transmission region A is the electromagnetic shielding region A.

[0012] The second shielding cover is formed by two regions, one of which is an electromagnetic shielding region B and the other of which is an electromagnetic wave transmission region B; the electromagnetic wave transmission region B is the region formed by the intersection of the spherical shell and the cone with the apex at the center of the second shielding cover, the center line being the Z-axis and the included angle between the generatrix and the center line being 30°; the rest of the region except the electromagnetic wave transmission region B is the electromagnetic shielding region B.

[0013] Further, the materials of the electromagnetic wave transmission region A and the electromagnetic wave transmission region B are wave-transparent composite materials; the materials of the electromagnetic shielding region A and the electromagnetic shielding region B are metal materials.

[0014] Further, the materials of the electromagnetic wave transmission region A and the electromagnetic wave transmission region B are wave-transparent composite materials; the materials of the electromagnetic shielding region A and the electromagnetic shielding region B are materials treated by metallization on the surface of wave-transparent composite materials.

[0015] Further, the central angle of the fan-shaped symmetrical surface of the first shielding cover and the second shielding cover is 120°.

[0016] Further, the device further comprises a shielding cover fixing mechanism and a mounting bracket.

[0017] The mounting bracket is composed of a fixed column and two circular arc rods; the fixed column is fixed on the outer circumferential surface of the dragon ball, and the two circular arc rods are symmetrically fixed on the two sides of the fixed column and form a semicircular structure to surround the outside of the dragon ball; wherein the two circular arc rods are not in contact with the dragon ball;

[0018] The end of each circular arc rod is provided with a shielding cover fixing mechanism, and the shielding cover fixing mechanism comprises a rotating shaft; the rotating shafts of the two shielding cover fixing mechanisms are coaxial and coaxial with the diameter of the dragon ball; the rotating shafts are fixed between the ends of the circular arc rods and the dragon ball;

[0019] The first shielding cover and the second shielding cover are connected with the two shielding cover fixing mechanisms, so that the first shielding cover and the second shielding cover are both surrounded outside the dragon ball.

[0020] Further, the specific connection that the first shielding cover and the second shielding cover are surrounded outside the dragon ball is:

[0021] The radius of the dragon ball is R; the inner diameter of the first shielding cover is R1, and the thickness is D; the inner diameter of the second shielding cover is R2, and the thickness is D, and R2>R, R2+D

[0022] The second shielding cover surrounds the outside of the dragon ball, the two ends of the second shielding cover are respectively sleeved on the rotating shafts of the two shielding cover fixing mechanisms, and the axis of the second shielding cover is coaxial with the rotating shafts, so that the second shielding cover can rotate around the rotating shafts, and the second shielding cover is processed with a guide groove for avoiding the fixed column of the mounting bracket; the first shielding cover surrounds the outside of the second shielding cover, the two ends of the first shielding cover are respectively sleeved on the rotating shafts of the two shielding cover fixing mechanisms, and the axis of the first shielding cover is coaxial with the rotating shafts, so that the first shielding cover can rotate around the rotating shafts, and the first shielding cover is processed with a guide groove for avoiding the fixed column of the mounting bracket.

[0023] Further, the shielding cover fixing mechanism further comprises a locking mechanism installed on the rotating shaft; the locking mechanism is used to compact the gap between the first shielding cover and the second shielding cover, and to position and fix the two first shielding covers and the second shielding cover after being rotated into place.

[0024] Further, the shielding cover fixing mechanism is made of a wave-penetrating composite material.

[0025] Further, the coplanar plane A is formed by the center of the dragon ball, the axis of the rotating shaft and the axis of the fixed column, the first shielding cover and the second shielding cover are symmetrically rotated relative to the plane A, that is, the included angle formed by the first shielding cover and the second shielding cover with the plane A is equal when they rotate, and the included angle is θ, then the opening angle of the first shielding cover and the second shielding cover is 2θ;

[0026] Let the plane perpendicular to the fixed column axis of the mounting support be plane B, when the electromagnetic wave incidence direction is perpendicular to the plane B, the azimuth angle of the electromagnetic wave incidence direction is 0°; when the azimuth angle of the electromagnetic wave incidence direction is 0°, the RCS engineering estimation value σ is calculated by formula (1):

[0027]

[0028] Wherein, λ is the wavelength of the electromagnetic wave, S is the projection area of the Luneberg sphere exposed part + the electromagnetic wave transparent area A of the first shielding cover + the electromagnetic wave transparent area B of the second shielding cover seen in the plane B direction, which can be calculated in theory.

[0029] By applying the technical scheme, the present application has the following beneficial effects:

[0030] (1) The present application discloses a passive adjustable RCS radar target simulation device, by adjusting the opening angle of the first shielding cover and the second shielding cover, the target RCS characteristic output is adjustable without changing the original radar target simulation device physical size.

[0031] (2) The present application discloses a passive adjustable RCS radar target simulation device, by setting the electromagnetic wave transparent area on the first shielding cover and the second shielding cover, the radar target simulation device has the characteristics of wide RCS characteristic output dynamic range, wide angle domain, flat output, etc. BRIEF DESCRIPTION OF DRAWINGS

[0032] The accompanying drawings, which are included to provide a further understanding of the embodiments of the application and constitute a part of this specification, illustrate embodiments of the application and together with the description assist in explaining the principles of the application. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0033] Figure 1 Structure diagram of the passive adjustable RCS radar target simulation device of the present application Figure 1 ;

[0034] Figure 2 Structure diagram of the passive adjustable RCS radar target simulation device of the present application Figure 2 ;

[0035] Figure 3 Division diagram of the electromagnetic wave transparent area of the first shielding cover of the present application

[0036] Figure 4Fig. 1 is a schematic diagram of the projection area of the present application in the plane perpendicular to the radar line-of-sight plane;

[0037] Figure 5 Fig. 1 is a schematic diagram of the projection area of the present application in the plane perpendicular to the radar line-of-sight plane;

[0038] Figure 6 Fig. 1 is a schematic diagram of the projection area of the present application in the plane perpendicular to the radar line-of-sight plane;

[0039] Fig. 1 is a schematic diagram of the projection area of the present application in the plane perpendicular to the radar line-of-sight plane; DETAILED DESCRIPTION

[0040] It should be noted that the embodiments and the features in the embodiments in the present application can be combined with each other without conflict. The technical solutions in the embodiments of the present application will be described clearly and completely with reference to the drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. The description of the at least one exemplary embodiment is actually only illustrative, but not as any limitation on the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0041] It should be noted that the terms used herein are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and it should also be understood that when the terms "comprise" and / or "include" are used in the specification, there is a feature, step, operation, device, component and / or combination thereof.

[0042] The relative arrangement of parts and steps, numerical expressions, and numerical values set forth in the examples herein are not intended to limit the scope of the application unless specifically stated otherwise. It is to be understood that the drawings are not necessarily to scale as the dimensions of the parts shown are for the purpose of illustration and description only and not to limit the scope of the application. Techniques, methods, and devices known to those of ordinary skill in the relevant art can not be discussed in detail, but should be considered as part of the description of the application. In all examples shown and discussed herein, any specific value should be interpreted as merely an example and not a limitation. Thus, other examples of the example embodiments can have different values. It should be noted that like reference numerals and letters refer to like items in the several views of the drawings, and thus, once an item is defined in one view, it need not be discussed further in subsequent views.

[0043] The embodiment provides a passive adjustable RCS radar target simulation device, referring to the accompanying drawings Figures 1-2 , comprising: a dragon ball 1, a first shielding cover, a second shielding cover, a shielding cover fixing mechanism 6 and a mounting bracket 7.

[0044] The radius of the dragon ball 1 is R.

[0045] The mounting bracket 7 is composed of a fixed column and two circular arc rods. The fixed column is fixed on the outer circumferential surface of the dragon ball 1 by bonding, and the two circular arc rods are symmetrically fixed on the two sides of the fixed column and form a semicircular structure to surround the outside of the dragon ball 1. Among them, the two circular arc rods are not in contact with the dragon ball 1. In the embodiment, the fixed column and the two circular arc rods are integrally formed. The mounting bracket 7 is used for mounting the shielding cover fixing mechanism 6 and the dragon ball 1, and simultaneously provides an external mounting interface.

[0046] Each end of each circular arc rod is provided with a shielding cover fixing mechanism 6. The shielding cover fixing mechanism 6 comprises a rotating shaft and a locking mechanism. The rotating shafts of the two shielding cover fixing mechanisms 6 are coaxial and are coaxial with the diameter of the dragon ball 1. The rotating shaft is fixed between the end of the circular arc rod and the dragon ball 1, and the locking mechanism is mounted on the rotating shaft. The shielding cover fixing mechanism 6 is made of a wave-transparent composite material.

[0047] The first shielding cover is a partial thin-layer spherical shell structure, the inner diameter of the partial thin-layer spherical shell structure is R1, and the thickness is D. The structure of the first shielding cover is 1 / 4 spherical structure to 1 / 2 spherical structure. The first shielding cover of the embodiment is 1 / 3 spherical structure, specifically: the first shielding cover has two symmetrical surfaces, one of which is semicircular and the other of which is fan-shaped. The central angle of the fan-shaped surface is greater than 90° and less than 180°. In the embodiment, the central angle of the fan-shaped surface of the first shielding cover is 120°.

[0048] The first shielding cover is formed by two areas, one area is the electromagnetic shielding area A2, and the other part is the electromagnetic wave transparent area A4; the electromagnetic wave transparent area A4 is: the area where the cone formed by the center of the first shielding cover is the vertex, the axis of the first shielding cover is the center line, and the angle between the generatrix and the center line is 30 degrees and intersects the spherical shell, as shown in the attached figure. Figure 3 As shown; in this embodiment, there are two electromagnetic wave transparent areas A4, which are respectively located at the two tips of the first shielding cover; the rest of the parts except the electromagnetic wave transparent areas A4 are electromagnetic shielding areas A2; the material of the electromagnetic wave transparent areas A4 is a wave transparent composite material; the material of the electromagnetic shielding areas A2 is a metal material, or a material with a metalized surface of the wave transparent composite material.

[0049] The second shielding cover has the same structure as the first shielding cover but different sizes. The second shielding cover is also a partial thin-layer spherical shell structure. The inner diameter of the partial thin-layer spherical shell structure is R2, the thickness is D, and R2>R, R2+D<R1; the structure of the second shielding cover is a 1 / 4 sphere structure to a 1 / 2 sphere structure, while the first shielding cover of this embodiment is a 1 / 3 sphere structure. Specifically, the second shielding cover has two symmetry planes, one symmetry plane is semicircular, and the other symmetry plane is sector-shaped; the central angle of the sector-shaped symmetry plane is greater than 90° and less than 180°; in this embodiment, the central angle of the sector-shaped symmetry plane of the second shielding cover is 120°;

[0050] The second shielding cover is formed by two areas, one area is the electromagnetic shielding area B3, and the other area is the electromagnetic wave-transparent area B5; the electromagnetic wave-transparent area B5 is: the area where a cone formed by taking the center of the second shielding cover as the vertex, the axis of the second shielding cover as the center line, and the angle between the busbar and the center line is 30° intersects the spherical shell; in this embodiment, there are two electromagnetic wave-transparent areas B5, which are respectively located at the two tips of the second shielding cover; the rest of the area except the electromagnetic wave-transparent areas B5 are all electromagnetic shielding areas B3; the material of the electromagnetic wave-transparent area B5 is a wave-transparent composite material; the material of the electromagnetic shielding area B3 is a metal material, or a material with a metalized surface of a composite wave-transparent material.

[0051] The first shielding cover and the second shielding cover are connected with the two shielding cover fixing mechanisms 6, so that the first shielding cover and the second shielding cover are both surrounded outside the dragon ball 1, and the first shielding cover, the second shielding cover and the dragon ball are coaxial, and the axis of the coaxial is the Z axis; the specific connection is that the second shielding cover is surrounded outside the dragon ball 1, the two sharp ends of the second shielding cover are respectively sleeved on the rotating shafts of the two shielding cover fixing mechanisms 6, and the axis (i.e. the Z axis) of the second shielding cover is coaxial with the rotating shafts, so that the second shielding cover can rotate around the rotating shafts, and the second shielding cover is processed with a guide groove for avoiding the fixing column of the installation support 7, to prevent the fixing column from interfering with the rotation of the second shielding cover; the first shielding cover is surrounded outside the second shielding cover, the two sharp ends of the first shielding cover are respectively sleeved on the rotating shafts of the two shielding cover fixing mechanisms 6, and the axis (i.e. the Z axis) of the first shielding cover is coaxial with the rotating shafts, so that the first shielding cover can rotate around the rotating shafts, and the first shielding cover is processed with a guide groove for avoiding the fixing column of the installation support 7, to prevent the fixing column from interfering with the rotation of the first shielding cover; the locking mechanism of the shielding cover fixing mechanism 6 is used to compact the gap between the first shielding cover and the second shielding cover, to realize the positioning and fixing of the two first shielding covers and the second shielding cover after being rotated in place; in this embodiment, the locking mechanism adopts a screw-nut structure.

[0052] In this embodiment, the opening angle of the first shielding cover and the second shielding cover is adjusted by rotating the first shielding cover and the second shielding cover, to realize the control of the wave quantity of the electromagnetic wave entering into the dragon ball 1; the coplanar plane A is formed by the ball center of the dragon ball 1, the axis of the rotating shaft and the axis of the fixing column, and the first shielding cover and the second shielding cover are symmetrically rotated relative to the plane A, that is, the included angle formed by the first shielding cover and the second shielding cover and the plane A is equal, and the included angle is θ, so that the opening angle of the first shielding cover and the second shielding cover is 2θ;

[0053] When the first shielding cover and the second shielding cover rotate around the rotating shaft and rotate to the completely closed state, that is, θ=0°, and the opening angle is 0°, as shown in Figure 4 (a), at this time, the dragon ball 1 is electromagnetically shielded, and no electromagnetic wave can enter the inside of the dragon ball 1, and the RCS theoretical simulation value of the radar target simulation device reaches the minimum value;

[0054] When the first shielding cover and the second shielding cover rotate around the rotating shaft and rotate to the completely opened state, that is, θ=90°, and the opening angle is 180°, as shown in Figure 4 (c), at this time, the whole dragon ball 1 is exposed in the electromagnetic wave irradiation area, and the RCS theoretical simulation value of the radar target simulation device reaches the maximum value;

[0055] When the first shielding cover and the second shielding cover rotate around the rotating shaft and rotate to the completely half-opened state, that is, 0°<θ<90°, and the opening angle is between 0° and 180°, as shown inFigure 4 (b) shown, at this time a part of the dragon ball 1 is exposed in the electromagnetic wave irradiation area, the RCS theoretical simulation value of the radar target simulation device is between the maximum value and the minimum value;

[0056] Therefore, by adjusting the opening angle of the first and second shielding covers, the adjustable RCS characteristic output of the radar target simulation device is realized.

[0057] Let the plane perpendicular to the fixed column axis of the mounting bracket 7 be plane B, when the electromagnetic wave incidence direction is perpendicular to the plane B, the azimuth angle of the electromagnetic wave incidence direction is 0°; when the azimuth angle of the electromagnetic wave incidence direction is 0°, the RCS theoretical simulation value of the radar target simulation device does not appear obvious attenuation; in the embodiment, the RCS engineering estimation value σ (RCS engineering estimation value σ is an estimation of the RCS theoretical simulation value) when the azimuth angle of the electromagnetic wave incidence direction is 0° can be calculated by formula (1):

[0058]

[0059] Wherein, λ is the wavelength of the electromagnetic wave, S is the projection area of the exposed part of the dragon ball 1 + the electromagnetic wave transparent area A4 of the first shielding cover + the electromagnetic wave transparent area B5 of the second shielding cover in the plane perpendicular to the radar line-of-sight plane, that is, the projection area of the exposed part of the dragon ball 1 + the electromagnetic wave transparent area A4 of the first shielding cover + the electromagnetic wave transparent area B5 of the second shielding cover in the plane B direction, the value can be calculated in theory, as shown in the orange area + yellow area + green area in the attached Figure 5 ; S is related to the radius R of the dragon ball 1, the inner diameter R1 and thickness D of the first shielding cover, the inner diameter R2 and thickness D of the second shielding cover, and the opening angle 2θ of the first and second shielding covers; therefore, the RCS theoretical simulation value of the radar target simulation device is related to the radius R of the dragon ball 1, the inner diameter R1 and thickness D of the first shielding cover, the inner diameter R2 and thickness D of the second shielding cover, and the opening angle 2θ of the first and second shielding covers;

[0060] The embodiment gives the RCS measured value curve of the radar target simulation device at 9.4 GHz when the diameter 2R of the dragon ball 1 is 176 mm, different opening angles 2θ, and different azimuth angles, as shown in Figure 6 , the abscissa is the azimuth angle (unit: °), and the ordinate is the RCS measured value (unit: dB㎡), from Figure 5It can be seen that when the azimuth angle is 0°, the greater the θ is, the greater the RCS measured value is, and the RCS characteristic output of the embodiment can be adjusted, the output dynamic range is wide, the action angle range is wide, the output is flat and the like can be seen from the RCS measured value; in addition, according to the RCS theoretical simulation value required by the radar target simulation device and formula (1), S can be calculated, and the opening angle 2θ of the first shielding cover and the second shielding cover can be calculated, after the opening angle 2θ of the first shielding cover and the second shielding cover is adjusted to the calculated angle, the RCS is measured, and by comparing the RCS measured value with the RCS theoretical simulation value, the feasibility of the embodiment is proved.

[0061] For the purposes of the description hereinafter, spatially relative terms, such as "above", "below", "up", "down", "top", "bottom", "horizontal", "vertical", "left", "right", "front", "rear", "upper", "lower", "horizontal", "vertical", "lateral", "longitudinal" and the like, can be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientations depicted in the figures. For example, if a device in the figures is inverted, elements described as "above" or "up" other elements or features would then be oriented "below" or "down" the other elements or features. Thus, the exemplary term "above" can encompass both an orientation of above and below. The device can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. The terms "first", "second", "third", etc., do not necessarily indicate any ordinal, chronological or other sequence unless expressly stated to do so.

[0062] In addition, it should be noted that the use of "first", "second", and the like words of distinction do not connote any meaning of special significance, and are merely used to distinguish the corresponding parts, and therefore cannot be understood as limiting the scope of protection of the present application.

[0063] The preferred embodiments of the present application have been described above with the preferred embodiments; the present application is not limited to the above, and for those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A passive adjustable RCS radar target simulation device, characterized in that: include: Longbo sphere, first shield, second shield; The first shielding cover and the second shielding cover are both partial spherical shell structures, and the partial spherical shell structures have two symmetry planes, one symmetry plane is semicircular, and the other symmetry plane is sector-shaped; the central angle of the sector is greater than 90° and less than 180°; The first shielding cover and the second shielding cover are both surrounded by the outside of the Luneburg sphere, and the first shielding cover, the second shielding cover and the Luneburg sphere are coaxial, and the axis of the coaxial cover is made into the Z axis. The first shielding cover and the second shielding cover can both rotate around the Z axis. By adjusting the opening angle of the first shielding cover and the second shielding cover, the exposed area of ​​the Luneburg sphere facing the incident direction of the electromagnetic wave is adjusted, and then the amount of electromagnetic waves entering the Luneburg sphere is adjusted.

2. A passive adjustable RCS radar target simulation device as claimed in claim 1, characterized in that: The first shielding cover is formed of two areas, one area is the electromagnetic shielding area A, and the other area is the electromagnetic wave-transmitting area A. The electromagnetic wave-transmitting area A is the area where the cone formed by the center of the first shielding cover is as the vertex, the Z axis is as the center line, and the angle between the generatrix and the center line is 30 degrees intersects the spherical shell. Except for the electromagnetic wave-transmitting area A, the rest of the area is the electromagnetic shielding area A. The second shielding cover is formed by two areas, one area is the electromagnetic shielding area B, and the other area is the electromagnetic wave-transmitting area B; the electromagnetic wave-transmitting area B is: the area where the cone formed with the center of the second shielding cover as the vertex, the Z axis as the center line, and the angle between the busbar and the center line is 30° intersects the spherical shell; the rest of the area except the electromagnetic wave-transmitting area B is the electromagnetic shielding area B.

3. A passive adjustable RCS radar target simulation device as claimed in claim 2, characterized in that: The electromagnetic wave-transmitting area A and the electromagnetic wave-transmitting area B are made of a wave-transmitting composite material; the electromagnetic shielding area A and the electromagnetic shielding area B are made of a metal material.

4. A passive adjustable RCS radar target simulation device as claimed in claim 2, characterized in that: The electromagnetic wave-transmitting area A and the electromagnetic wave-transmitting area B are made of a wave-transmitting composite material; the electromagnetic shielding area A and the electromagnetic shielding area B are made of a wave-transmitting composite material with its surface metallized.

5. A passive adjustable RCS radar target simulation device according to any one of claims 1 to 4, characterized in that: The central angles of the sector-shaped symmetric planes of the first shielding cover and the second shielding cover are both 120°.

6. A passive adjustable RCS radar target simulation device as claimed in claim 2, characterized in that: Also included is a shield cover fixing mechanism and a mounting bracket; The mounting bracket is composed of a fixed column and two arc rods; the fixed column is fixed to the outer circumference of the Luneburg sphere, and the two arc rods are symmetrically fixed on both sides of the fixed column to form a semicircular structure, surrounding the outside of the Luneburg sphere; wherein, the two arc rods do not contact the Luneburg sphere; A shield fixing mechanism is installed at the end of each arc rod, and the shield fixing mechanism includes a rotation axis; the rotation axes of the two shield fixing mechanisms are coaxial and coaxial with the diameter of the Luneburg sphere; the rotation axis is fixed between the end of the arc rod and the Luneburg sphere; The first shielding cover and the second shielding cover are both connected to two shielding cover fixing mechanisms, so that the first shielding cover and the second shielding cover are both surrounded by the outside of the Luneburg sphere.

7. A passive adjustable RCS radar target simulation device as claimed in claim 6, characterized in that: The specific connection between the first shield and the second shield surrounding the outside of the Luneburg sphere is: The radius of the Luneburg sphere is R; the inner diameter of the first shielding cover is R1, and the thickness is D; the inner diameter of the second shielding cover is R2, and the thickness is D, and R2>R, R2+D<R1; The second shielding cover is surrounded by the outside of the Luneburg sphere, and the two ends of the second shielding cover are respectively mounted on the rotating shafts of the two shielding cover fixing mechanisms, and the axis of the second shielding cover is coaxial with the rotating shaft, so that the second shielding cover can rotate around the rotating shaft, and the second shielding cover is processed with a guide groove for avoiding the fixed column of the mounting bracket; the first shielding cover is surrounded by the outside of the second shielding cover, and the two ends of the first shielding cover are respectively mounted on the rotating shafts of the two shielding cover fixing mechanisms, and the axis of the first shielding cover is coaxial with the rotating shaft, so that the first shielding cover can rotate around the rotating shaft, and the first shielding cover is processed with a guide groove for avoiding the fixed column of the mounting bracket.

8. A passive adjustable RCS radar target simulation device as claimed in claim 7, characterized in that: The shielding cover fixing mechanism also includes a locking mechanism, which is installed on the rotating shaft; the locking mechanism is used to compact the gap between the first shielding cover and the second shielding cover, and to position and fix the two first shielding covers after they are rotated into place.

9. A passive adjustable RCS radar target simulation device according to any one of claims 6 to 8, characterized in that: The shielding cover fixing mechanism is made of wave-transmitting composite material.

10. The passive adjustable RCS radar target simulation device according to claim 6, characterized in that: Let the coplanar surface formed by the center of the Luneburg sphere, the axis of the rotation shaft, and the axis of the fixed column be plane A. The first shield and the second shield rotate symmetrically with respect to plane A. That is, when the first shield and the second shield rotate, the angles formed with plane A are equal. Let this angle be θ. Then the opening angle between the first shield and the second shield is 2θ. Let the plane perpendicular to the axis of the fixed column of the mounting bracket be plane B. When the incident direction of the electromagnetic wave is perpendicular to plane B, the azimuth angle of the incident direction of the electromagnetic wave is 0°. When the azimuth angle of the incident direction of the electromagnetic wave is 0°, the RCS engineering estimated value σ is calculated by formula (1): Wherein, λ is the wavelength of the electromagnetic wave, S is the projected area of ​​the exposed portion of the Luneburg sphere + the electromagnetic wave-transmitting area A of the first shielding cover + the electromagnetic wave-transmitting area B of the second shielding cover on plane B when looking in the direction of plane B. This value can be calculated theoretically.

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