Low frequency band passive scattering radar echo enhancer

Abstract

The application relates to a low-frequency passive scattering radar echo enhancer, which comprises a first reflecting layer, a medium layer and a third reflecting layer in sequence along the incident direction of electromagnetic waves. The first reflecting layer comprises a reflecting ring, the second reflecting layer comprises three reflecting rings which are concentrically sleeved at intervals, the cross sections of the three reflecting rings are the same, the interval distances of the adjacent reflecting rings are the same, and the interval distances are 1-2.5 times of the radial dimension of the cross section of the ring body. Each reflecting ring is a circular ring, the reflecting ring of the first reflecting layer is the same as the outermost reflecting ring of the second reflecting layer, the ratio of the outer diameter to the resonant wavelength ranges from 0.27 to 0.29, and the outer diameters of the reflecting ring of the first reflecting layer and the outermost reflecting ring of the second reflecting layer are the same as the diameter of the medium layer which is in the shape of a cylinder, and are concentrically arranged with the medium layer. The enhancer has the advantages of simple structure, small size, and solves the problem that the conventional passive scatterer cannot effectively scatter the echo of low-frequency electromagnetic waves under the condition of small size, and has a wide angle domain.

Description

Technical Field

[0001] This invention relates to the field of radar echo enhancer technology, and more particularly to a low-frequency passive scattering radar echo enhancer. Background Technology

[0002] In the low-frequency band, because the size of the aircraft is similar to the radar wavelength, it is difficult to achieve effective radar cross-section (RCS) reduction, making stealth difficult to achieve. Therefore, low-frequency anti-stealth technology is a current research focus. In practical engineering applications, how to reproduce the electromagnetic backscattered echo of a large target in the low-frequency band at low cost and high efficiency using small structures or devices within a very small space is of great significance for the research of anti-stealth technology for low-frequency targets.

[0003] Commonly used methods for enhancing backscattered echoes include active modulation simulation and passive scattering simulation. Active modulation simulation is based on simulating the secondary emission of received electromagnetic waves after modulation and amplification, but it generally involves large equipment sizes and suffers from system instability and susceptibility to interference. Passive scattering simulation offers advantages such as high reliability, good stability, and strong anti-interference performance; however, commonly used passive scattering components such as flat plates, metal spheres, dihedrals, trihedrals, and Luneburg spheres typically operate at higher frequencies (such as the X-band), making it difficult to achieve effective enhancement of low-frequency backscattered echoes under small-size conditions. Therefore, breakthroughs in new technologies for simulating and physically reproducing low-frequency electromagnetic scattering characteristics are becoming increasingly urgent. Summary of the Invention

[0004] The purpose of this invention is to provide a low-frequency passive scattering radar echo enhancer, which solves the problem that conventional passive scatterers are difficult to effectively enhance the scattered echo of low-frequency electromagnetic waves under small size conditions.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a low-frequency passive scattering radar echo enhancer, wherein in a first implementation, the components along the incident direction of the electromagnetic wave sequentially include:

[0006] The first reflective layer includes a first reflective ring, which is a circular ring and satisfies the following condition: the ratio of the outer diameter of the first reflective ring to the resonant wavelength is in the range of 0.27 to 0.29.

[0007] The dielectric layer is a cylinder, the diameter of the end face of which is the same as the outer diameter of the first reflective ring, and the first reflective ring is concentrically disposed on the end face of the cylinder; and

[0008] The second reflective layer includes three reflective rings, all of which are circular and are arranged concentrically at intervals. From the outside to the inside, they are the second reflective ring, the third reflective ring, and the fourth reflective ring. The second, third, and fourth reflective rings have the same cross-section, and the interval between adjacent reflective rings is the same. The interval is 1 to 2.5 times the radial dimension of the cross-section of the ring.

[0009] The second reflective ring is the same as the first reflective ring.

[0010] In conjunction with the first implementation of the first aspect, in its second implementation, the material of the dielectric layer satisfies the following requirements:

[0011] The relative permittivity is around 2.5, and the dielectric loss tangent is less than 3 × 10⁻⁶. -4 .

[0012] In conjunction with the first or second implementation of the first aspect, in its third implementation, the material of the dielectric layer is polystyrene, polypropylene, or a fluorinated polymer.

[0013] In combination with any of the first to third implementations of the first aspect, in its fourth implementation, the first reflective ring, the second reflective ring, the third reflective ring and the fourth reflective ring are all made of aluminum foil.

[0014] In combination with any of the first to fourth implementations of the first aspect, in its fifth implementation, the cross-sections of the first, second, third, and fourth reflective rings are rectangular, and the radial dimension of the cross-sections is 5 to 10 mm.

[0015] The axial dimensions of the first reflective ring, the second reflective ring, the third reflective ring, and the fourth reflective ring are 1 to 3 mm.

[0016] The axial length of the cylinder is 80–150 mm.

[0017] Secondly, the present invention also provides another low-frequency passive scattering radar echo enhancer, in which, in its first implementation, the components along the incident direction of the electromagnetic wave are sequentially included as follows:

[0018] The first reflective layer includes a first reflective ring, which is a square ring and satisfies the following condition: the ratio of the side length of the first reflective ring to the resonant wavelength is in the range of 0.215 to 0.242.

[0019] The dielectric layer is a cuboid, the cross-section of which is square perpendicular to the incident direction of the electromagnetic wave. The side length of the first reflective ring is the same as the side length of the end face of the cuboid, and each side of the first reflective ring is aligned with each side of the end face of the cuboid.

[0020] The second reflective layer includes three reflective rings, which are square rings and are nested in parallel at equal intervals. From the outside to the inside, they are the second reflective ring, the third reflective ring, and the fourth reflective ring. The cross-sections of the second, third, and fourth reflective rings are the same, the spacing between adjacent reflective rings is the same, and the spacing is 1 to 2.5 times the dimension of the cross-section of the ring in the spacing direction.

[0021] The second reflective ring is the same as the first reflective ring, and each side of the second reflective ring is aligned with each side of the end face of the cuboid.

[0022] In conjunction with the first implementation of the second aspect, in its second implementation, the material of the dielectric layer satisfies the following requirements:

[0023] The relative permittivity is around 2.5, and the dielectric loss tangent is less than 3 × 10⁻⁶. -4 .

[0024] In conjunction with the first or second implementation of the second aspect, in its third implementation, the material of the dielectric layer is polystyrene, polypropylene, or a fluorinated polymer.

[0025] In combination with any of the first to third implementations of the second aspect, in its fourth implementation, the first reflective ring, the second reflective ring, the third reflective ring and the fourth reflective ring are all made of aluminum foil.

[0026] In conjunction with any of the first to fourth implementations of the second aspect, in its fifth implementation, the cross-sections of the first, second, third, and fourth reflective rings are rectangular, and the dimensions of the rings transversely in the interval direction of each reflective ring are 5 to 10 mm.

[0027] The dimensions of the first, second, third, and fourth reflective rings in the electromagnetic wave incident direction are 1–3 mm;

[0028] The length of the cuboid in the direction of electromagnetic wave incidence is 80-150 mm.

[0029] The above-mentioned technical solution of the present invention has the following advantages: The low-frequency passive scattering radar echo enhancer provided by the present invention includes, sequentially along the incident direction of the electromagnetic wave, a first reflective layer, a dielectric layer, and a third reflective layer. The first reflective layer includes a reflective ring, and the second reflective layer includes three concentrically spaced reflective rings. The cross-sections of the three reflective rings are the same, and the spacing between adjacent reflective rings is the same, which is 1 to 2.5 times the radial dimension of the cross-section of the ring. Each reflective ring is a circular ring. The reflective rings of the first reflective layer and the outermost reflective ring of the second reflective layer are the same, with the ratio of their outer diameter to the resonant wavelength ranging from 0.27 to 0.29. The outer diameters of the reflective rings of the first reflective layer and the outermost reflective rings of the second reflective layer are the same as the diameter of the cylindrical dielectric layer, and they are all concentrically arranged with the dielectric layer. The electromagnetic wave first enters the first reflective layer, generating a backscattered echo. The electromagnetic wave continues to enter, passes through the dielectric layer, and reaches the third reflective layer, continuing to generate a backscattered echo. The two interact, thereby achieving RCS enhancement in the low-frequency band. By designing the structure and position of the first and second reflective layers, the radar echo enhancer captures low-frequency electromagnetic waves with longer wavelengths. By matching the outer diameter of the reflective ring with the resonant wavelength and then using resonant control, it effectively enhances the scattered echo of electromagnetic waves of a specified frequency. This radar echo enhancer has a simple structure and small size, solving the problem that conventional passive scatterers cannot effectively enhance the scattered echo of low-frequency electromagnetic waves under small size conditions, and also has a wide angular range.

[0030] The low-frequency passive scattering radar echo enhancer provided by this invention comprises, sequentially along the incident direction of the electromagnetic wave, a first reflective layer, a dielectric layer, and a third reflective layer. The first reflective layer includes a reflective ring, and the second reflective layer includes three parallel and equally spaced reflective rings. The three reflective rings have the same cross-section, and the spacing between adjacent reflective rings is 1 to 2.5 times the dimension of the cross-section of the ring in the spacing direction. Each reflective ring is a square ring. The outermost reflective ring of the first reflective layer is the same as that of the outermost reflective ring of the second reflective layer, with a side length to resonant wavelength ratio ranging from 0.215 to 0.242. Furthermore, the side lengths of the reflective rings of the first and second reflective layers are the same as the side length of the cross-section of the cuboid-shaped dielectric layer perpendicular to the incident direction of the electromagnetic wave. Each side of both is aligned with the side of the end face of the cuboid. Electromagnetic waves first strike the first reflector layer, generating a backscattered echo. The electromagnetic waves continue to strike, passing through the dielectric layer to reach the third reflector layer, where they continue to generate backscattered echoes. The interaction between these two layers enhances the RCS (Radar Cross Section) in the low-frequency band. By designing the structure and position of the first and second reflector layers, long-wavelength low-frequency electromagnetic waves are captured. Matching the outer diameter of the reflector ring to the resonant wavelength and then using resonant control achieves effective enhancement of the backscattered echo of electromagnetic waves at a specified frequency. This radar echo enhancer has a simple structure and small size, solving the problem of conventional passive scatterers' difficulty in effectively enhancing the backscattered echo of low-frequency electromagnetic waves under small-size conditions, and also possesses a wide angular range. Attached Figure Description

[0031] The accompanying drawings are provided for illustrative purposes only, and the proportions and quantities of the components in the drawings may not be consistent with the actual product.

[0032] Figure 1 This is a schematic diagram of a low-frequency passive scattering radar echo enhancer according to Embodiment 1 of the present invention;

[0033] Figure 2 yes Figure 1 Another structural diagram of a passive scattering radar echo enhancer in the mid-to-low frequency band;

[0034] Figure 3 yes Figure 1 A schematic diagram of one end of a passive scattering radar echo enhancer in the mid-to-low frequency band.

[0035] Figure 4 Figure 1 A schematic diagram of the other end of a passive scattering radar echo enhancer for mid-to-low frequency bands;

[0036] Figure 5 yes Figure 3 A schematic diagram of the AA cross-section;

[0037] Figure 6 yes Figure 1Schematic diagram of frequency versus backscattering RCS curves of a passive scattering radar echo enhancer in the mid-to-low frequency band.

[0038] Figure 7 yes Figure 1 Schematic diagram of azimuth and backscattering RCS curves of a passive scattering radar echo enhancer in the mid-to-low frequency band;

[0039] Figure 8 This is a schematic diagram of one end of a low-frequency passive scattering radar echo enhancer according to Embodiment 2 of the present invention;

[0040] Figure 9 Figure 8 A schematic diagram of the other end of a passive scattering radar echo enhancer for mid-to-low frequency bands;

[0041] Figure 10 yes Figure 8 Schematic diagram of frequency versus backscattering RCS curves of a passive scattering radar echo enhancer in the mid-to-low frequency band.

[0042] Figure 11 yes Figure 8 A schematic diagram of the azimuth and backscattering RCS curves of a passive scattering radar echo enhancer in the mid-to-low frequency band.

[0043] In the picture:

[0044] 1: First reflective layer;

[0045] 11: First reflection ring;

[0046] 2: Dielectric layer;

[0047] 3: Second reflective layer;

[0048] 31: Second reflective ring;

[0049] 32: Third reflection ring;

[0050] 33: Fourth reflection ring. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0052] Example 1

[0053] See Figures 1-5As shown, the low-frequency passive scattering radar echo enhancer provided in this embodiment of the invention includes a first reflective layer 1, a dielectric layer 2 and a third reflective layer 3 in sequence along the incident direction of the electromagnetic wave.

[0054] See Figure 1 , Figure 3 and Figure 5 As shown, the first reflective layer 1 includes a first reflective ring 11, which is a circular ring and satisfies the following condition: the ratio of the outer diameter of the first reflective ring 11 to the resonant wavelength is in the range of 0.27 to 0.29. For example, 0.27, 0.271, 0.275, 0.278, 0.28, 0.281, 0.282, 0.285, 0.287, 0.29, etc.

[0055] See Figures 1-4 As shown, the dielectric layer 2 is a cylinder, and the diameter of the end face of the cylinder is the same as the outer diameter of the first reflective ring 11. The first reflective ring 11 is disposed on the end face of the cylinder and is concentrically disposed with the dielectric layer 2. Preferably, the first reflective ring 11 is adhered and fixed to the end face of the cylinder.

[0056] See Figure 2 , Figure 4 and Figure 5 As shown, the second reflective layer 3 includes three reflective rings, all of which are circular and concentrically spaced. From the outside to the inside, they are a second reflective ring 31, a third reflective ring 32, and a fourth reflective ring 33. The cross-sections of the second reflective ring 31, the third reflective ring 32, and the fourth reflective ring 33 are the same, and the spacing between adjacent reflective rings is the same, with a spacing L. 间隔 The radial dimension L of the annular cross-section 径 It is 1 to 2.5 times that of the first reflective ring 11.

[0057] In operation, electromagnetic waves first strike the first reflective layer 1, generating a backscattered echo. The electromagnetic waves continue to strike, passing through the dielectric layer 2 to reach the third reflective layer 3, where they continue to generate backscattered echoes. The interaction between these two layers enhances the RCS (Radar Cross Section) in the low-frequency band. The dielectric layer 2 also provides structural support. By designing the structure and position of the first and second reflective layers, long-wavelength low-frequency electromagnetic waves are captured. Matching the outer diameter of the reflective ring to the resonant wavelength and then using resonance control effectively enhances the backscattered echo of electromagnetic waves at a specified frequency. This radar echo enhancer features a simple structure and small size, solving the problem of conventional passive scatterers failing to effectively enhance the backscattered echo of low-frequency electromagnetic waves under small-size conditions.

[0058] In this embodiment, the dielectric layer 2 can be made of a common dielectric material. In some implementations, preferably, the material of the dielectric layer 2 meets the following requirements: a relative permittivity of about 2.5 and a dielectric loss tangent of less than 3 × 10⁻⁶. -4 More preferably, the dielectric layer 2 is made of a material with high structural strength and high temperature resistance, such as polystyrene, polypropylene, fluorinated polymers, etc.

[0059] In this embodiment, the first reflective ring 11, the second reflective ring 31, the third reflective ring 32, and the fourth reflective ring 33 use reflective materials commonly used in radar echo enhancers. Preferably, the first reflective ring 11, the second reflective ring 31, the third reflective ring 32, and the fourth reflective ring 33 are all made of aluminum foil. More preferably, the first reflective ring 11, the second reflective ring 31, the third reflective ring 32, and the fourth reflective ring 33 are all made of aluminum foil sheets adhered to the dielectric layer 2.

[0060] In some preferred embodiments, the cross-sections of the first reflective ring 11, the second reflective ring 31, the third reflective ring 32, and the fourth reflective ring 33 are rectangular, and the radial dimension L of the cross-sections is... 径 The diameter is 5-10 mm. The axial dimension L of the cross-section of the first reflective ring 11, the second reflective ring 31, the third reflective ring 32, and the fourth reflective ring 33 is 5-10 mm. 轴 The diameter is 1-3 mm. The axial length of the cylinder serving as the medium layer 2 is 80-150 mm.

[0061] See Figure 6 and Figure 7 As shown in the figure, the backscattering RCS simulation results of a low-frequency passive scattering radar echo enhancer in this embodiment show that the backscattering RCS peak value is greater than 2 square meters at the 0.4 GHz frequency point.

[0062] Furthermore, the low-frequency passive scattering radar echo enhancer of this embodiment not only achieves the capture of low-frequency electromagnetic waves with longer wavelengths but also effectively enhances the scattered echo of electromagnetic waves of a specified frequency. See also Figure 7 As shown, the angular domain range of the half-dB value of the azimuth scan of the low-frequency passive scattering radar echo enhancer is within ±30°, which is wider than that of the more common flat plate and angular reflector.

[0063] In this embodiment, the second reflective ring 31 in the second reflective layer 3 is required to be the same as the first reflective ring 11, and the two reflective rings inside it can be replaced by a similar structure, such as a two-layer planar spiral structure.

[0064] Example 2

[0065] See Figure 8 and Figure 9As shown, the second embodiment is basically the same as the first embodiment, and the same parts will not be described again. The differences are as follows: The first reflection ring 11, the second reflection ring 31, the third reflection ring 32, and the fourth reflection ring 33 are all square rings and satisfy the following conditions: The ratio of the side length of the first reflection ring 11 to the resonant wavelength ranges from 0.215 to 0.242. For example, 0.215, 0.216, 0.217, 0.219, 0.22, 0.221, 0.225, 0.226, 0.228, 0.23, 0.232, 0.235, 0.238, 0.239, 0.24, 0.242, etc. The first reflection ring 11 and the second reflection ring 31 are the same.

[0066] The dielectric layer 2 is a cuboid, and the cross-section of the cuboid perpendicular to the electromagnetic wave incident direction is square. The side length of the first reflection ring 11 is the same as the side length of the end face of the cuboid where it is located, and each side of the first reflection ring 11 is aligned with each side of the end face of the cuboid where it is located. The side length of the second reflection ring 31 is the same as the side length of the end face of the cuboid where it is located, and each side of the second reflection ring 31 is respectively aligned with each side of the end face of the cuboid where it is located

[0067] In some embodiments, the cross-section of the ring bodies of the first reflection ring 11, the second reflection ring 31, the third reflection ring 32, and the fourth reflection ring 33 is rectangular, and the size of the cross-section of the ring bodies in the direction of the interval between the reflection rings is 5 - 10 mm. The size of the first reflection ring, the second reflection ring, the third reflection ring, and the fourth reflection ring in the electromagnetic wave incident direction is 1 - 3 mm. The length of the cuboid in the electromagnetic wave incident direction is 80 - 150 mm.

[0068] Refer Figure 10 and Figure 11 As shown, the simulation result of the backscattering RCS of a low-frequency passive scattering radar echo enhancer in this embodiment. At the 0.4 GHz frequency point, the peak value of the backscattering RCS is greater than 2 square meters. The angular range of the azimuth scan half dB value is within ±30°, which is wider than that of common flat plates and corner reflectors.

[0069] The parts not detailed in this invention are the prior art or common knowledge.

[0070] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that not every embodiment only contains an independent technical solution. In the case of no conflict between the solutions, the technical features mentioned in each embodiment can be combined in any way to form other embodiments that can be understood by those skilled in the art.

[0071] Furthermore, without departing from the scope of the present invention, modifications to the technical solutions described in the foregoing embodiments, or equivalent substitutions of some of the technical features, shall not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A low-frequency passive scattering radar echo enhancer, characterized in that, Along the incident direction of the electromagnetic wave, the following are included in sequence: The first reflective layer includes a first reflective ring, which is a circular ring and satisfies the following condition: the ratio of the outer diameter of the first reflective ring to the resonant wavelength is in the range of 0.27 to 0.

29. The dielectric layer is a cylinder, the diameter of the end face of which is the same as the outer diameter of the first reflective ring, and the first reflective ring is concentrically disposed on the end face of the cylinder; and The second reflective layer includes three reflective rings, all of which are circular and are arranged concentrically at intervals. From the outside to the inside, they are the second reflective ring, the third reflective ring, and the fourth reflective ring. The second, third, and fourth reflective rings have the same cross-section, and the interval between adjacent reflective rings is the same. The interval is 1 to 2.5 times the radial dimension of the cross-section of the ring. The second reflective ring is the same as the first reflective ring.

2. The low-frequency passive scattering radar echo enhancer according to claim 1, characterized in that: The material of the dielectric layer meets the following requirements: The relative permittivity is around 2.5, and the dielectric loss tangent is less than 3 × 10⁻⁶. -4 .

3. The low-frequency passive scattering radar echo enhancer according to claim 2, characterized in that: The material of the dielectric layer is polystyrene, polypropylene, or a fluorinated polymer.

4. The low-frequency passive scattering radar echo enhancer according to claim 1, characterized in that: The first, second, third, and fourth reflective rings are all made of aluminum foil.

5. The low-frequency passive scattering radar echo enhancer according to claim 1, characterized in that: The cross-sections of the first, second, third, and fourth reflective rings are rectangular, and the radial dimension of the cross-sections is 5–10 mm. The axial dimensions of the first reflective ring, the second reflective ring, the third reflective ring, and the fourth reflective ring are 1 to 3 mm. The axial length of the cylinder is 80–150 mm.

6. A low-frequency passive scattering radar echo enhancer, characterized in that, Along the incident direction of the electromagnetic wave, the following are included in sequence: The first reflective layer includes a first reflective ring, which is a square ring and satisfies the following condition: the ratio of the side length of the first reflective ring to the resonant wavelength is in the range of 0.215 to 0.

242. The dielectric layer is a cuboid, the cross-section of which is square perpendicular to the incident direction of the electromagnetic wave. The side length of the first reflective ring is the same as the side length of the end face of the cuboid, and each side of the first reflective ring is aligned with each side of the end face of the cuboid. The second reflective layer includes three reflective rings, which are square rings and are nested in parallel at equal intervals. From the outside to the inside, they are the second reflective ring, the third reflective ring, and the fourth reflective ring. The cross-sections of the second, third, and fourth reflective rings are the same, the spacing between adjacent reflective rings is the same, and the spacing is 1 to 2.5 times the dimension of the cross-section of the ring in the spacing direction. The second reflective ring is the same as the first reflective ring, and each side of the second reflective ring is aligned with each side of the end face of the cuboid.

7. The low-frequency passive scattering radar echo enhancer according to claim 6, characterized in that: The material of the dielectric layer meets the following requirements: The relative permittivity is around 2.5, and the dielectric loss tangent is less than 3 × 10⁻⁶. -4 .

8. The low-frequency passive scattering radar echo enhancer according to claim 7, characterized in that: The material of the dielectric layer is polystyrene, polypropylene, or a fluorinated polymer.

9. The low-frequency passive scattering radar echo enhancer according to claim 6, characterized in that: The first, second, third, and fourth reflective rings are all made of aluminum foil.

10. The low-frequency passive scattering radar echo enhancer according to claim 6, characterized in that: The cross-sections of the first, second, third, and fourth reflective rings are rectangular, and the dimensions of the rings across the spacing direction of each reflective ring are 5 to 10 mm. The dimensions of the first, second, third, and fourth reflective rings in the electromagnetic wave incident direction are 1–3 mm; The length of the cuboid in the direction of electromagnetic wave incidence is 80-150 mm.

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