Three-dimensional vertical P-band low-frequency absorbing structure based on metamaterials

Abstract

The present invention belongs to the technical field of absorbing materials, and specifically relates to a three-dimensional vertical P-band low-frequency absorbing structure based on metamaterials. The structure comprises a plurality of periodically arranged basic structures, wherein the basic structures include stacked reflective plates and separating dielectric plates. The separating dielectric plates are provided with cross-symmetrical vertical units, and the cross-symmetrical vertical units are provided with single elements. The single elements include a dielectric plate and a functional unit provided on the dielectric plate. The cross-symmetrical vertical units include a cross dielectric substrate composed of two vertical units arranged in a cross shape, and a metal layer located on the cross dielectric substrate. The present invention has a small size and a light weight, can obtain a more stable frequency response, and can achieve a good absorbing effect in the P-band and lower frequency bands.

Description

Technical Field

[0001] The present invention belongs to the technical field of absorbing materials, and in particular relates to a three-dimensional vertical P-band low-frequency absorbing structure based on metamaterials. Background Art

[0002] In recent years, a three-dimensional metamaterial absorbing structure composed of a periodic array of vertical structures has garnered widespread research attention. Metamaterials are emerging synthetic materials that, by varying the period of their unit structures and the electromagnetic induction interaction with electromagnetic waves, can manipulate the amplitude, phase, and polarization of electromagnetic waves. Amplitude manipulation can be applied to effectively absorb electromagnetic waves. This three-dimensional vertical structure is designed and implemented based on a two-dimensional planar absorber. By loading resistors and utilizing electromagnetic induction mechanisms, the energy of electromagnetic waves is further dissipated and absorbed within the vertical structure. In industries such as communications, there is a significant demand for electromagnetic testing, requiring researchers to construct microwave anechoic chambers as test spaces. The design and application of absorbing materials is crucial to ensuring the performance of these chambers. This three-dimensional vertical metamaterial structure, with its advantages of low-frequency absorption, low profile, and stable performance, has become a research hotspot for anechoic chamber absorbing material design. In military applications, as modern weaponry enters the stealth era, the demand for high-performance metamaterial absorbers capable of achieving stealth is increasing. In recent years, with the rapid development of low-frequency detection technology, high-efficiency electromagnetic absorbing metamaterial structures working in the P-band have become an effective means to reduce electromagnetic wave detection and the key to achieving stealth performance in various weapons and equipment.

[0003] While increasing the size and thickness can moderately reduce the operating frequency of metamaterial absorbers, ensuring strong absorption performance and bandwidth in the P-band remains challenging. Currently, most absorbers operate in the S-Ku band, and their stealth performance is insufficient to counteract anti-stealth technologies such as low-frequency detection. Furthermore, their stealth effectiveness is significantly reduced when encountering radars operating in lower-frequency bands than the P-band, thus limiting their application. Some metamaterial absorbers operating in the P-band operate at frequencies too high, failing to meet the absorption requirements of lower-frequency bands. To achieve this, some P-band absorbers utilize magnetic materials or a combination of magnetic materials and metamaterials. Magnetic materials have high permeability, allowing them to reduce the absorption frequency while maintaining a relatively small thickness. However, these materials suffer from the disadvantages of being heavy, costly, and difficult to conform to. Consequently, their application is limited. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a three-dimensional vertical P-band low-frequency absorbing structure based on metamaterials, which has a small size, light weight, can obtain a more stable frequency response, and can achieve better absorbing effects in the P-band and lower frequency bands.

[0005] An embodiment of the present invention provides a three-dimensional vertical P-band low-frequency absorbing structure based on metamaterials, comprising a plurality of periodically arranged basic structures, wherein the basic structures comprise a stacked and connected reflective plate and a separation medium plate, wherein the separation medium plate is provided with a cross-symmetrical vertical unit, wherein the cross-symmetrical vertical unit is provided with a unit element, wherein the unit element comprises a medium plate (11) and a functional unit provided on the medium plate;

[0006] The cross-symmetrical vertical unit includes a cross dielectric substrate composed of two vertical units intersecting in a cross shape, and a metal layer located on the cross dielectric substrate. The vertical unit includes a dielectric substrate, on which a C-shaped patch and a spiral patch located inside the C-shaped patch are provided, and a C-shaped patch energy dissipation component is provided on the C-shaped patch. The cross dielectric substrate divides the space into four quadrants, and the C-shaped patches located on the surfaces of the two vertical units in each quadrant are connected, and the spiral patches located on the surfaces of the two vertical units in each quadrant are connected.

[0007] The functional unit includes an outer closed-loop patch and an inner closed-loop patch located inside the outer closed-loop patch. The outer closed-loop patch has at least two protruding corners, a concave area is provided between the protruding corners, a connecting patch is connected between the concave area and the inner closed-loop patch, a middle closed-loop patch is further provided inside the protruding corners, and energy-consuming parts are provided on the outer closed-loop patch and / or the connecting patch.

[0008] The closed-loop patch refers to a structure that is itself a closed loop, and the patch refers to a strip made of a conductive material (such as metal, which can be copper); the protruding corner refers to the part that protrudes from the outer closed-loop patch. Since it protrudes from the outer closed-loop patch, there is a concave area between the protruding corners. The protruding corners and the concave area are both distinguished relative to the center of the outer closed-loop patch, that is, the protruding corners are farther away from the center of the outer closed-loop patch than the concave area.

[0009] The C-shaped patch and the spiral patch are provided on both sides of the dielectric substrate.

[0010] The cross dielectric substrate is a vertical unit in xoy In-plane winding z The center of the cross dielectric substrate is the center of the unit element, the reflector and the separation dielectric plate, which can achieve full polarization characteristics with stable transmission performance when irradiated by various polarized electromagnetic waves.

[0011] Optionally, the C-shaped patch is in the shape of a rectangle lacking one side, and the spiral patch is in the shape of straight line segments connected end to end extending outward in a spiral from a center point, with adjacent straight line segments being perpendicular.

[0012] Optionally, the reflective plate is a metal plate, the functional unit is made of a metal material, and the energy dissipation component is a resistor.

[0013] Optionally, the end of the connecting patch is located inside the inner closed-loop patch; and a sealing patch is provided at the end of the connecting patch.

[0014] Optionally, the protruding angles are evenly distributed around the center point of the functional unit, and the center of the inner closed-loop patch is the center point of the functional unit.

[0015] Optionally, the protruding corner is arc-shaped, the middle closed-loop patch is circular, and the inner closed-loop patch is rectangular.

[0016] Optionally, the protruding corner is in the shape of a 3 / 4 circular ring, and the inner closed-loop patch is in the shape of a square.

[0017] Optionally, the number of the protruding corners is four, the number of the middle closed-loop patches is four, and the number of the connecting patches is four.

[0018] Optionally, the energy-consuming parts are evenly distributed around the center point of the functional unit.

[0019] Optionally, the middle closed-loop patch is not connected to either the outer closed-loop patch or the inner closed-loop patch.

[0020] Furthermore, the perimeter of the unit element, the separation medium plate and the reflective plate is 165 mm.

[0021] Furthermore, the inner radius of the outer closed-loop patch is 28 mm and the width is 2 mm; the inner radius of the middle closed-loop patch is 15 mm and the width is 3.5 mm; the inner side length of the inner closed-loop patch is 18 mm and the width is 2 mm.

[0022] Furthermore, the length of the concave patch is 8 mm, the length of the connecting patch is 26 mm, and the length of the end-sealing patch is 4 mm; all the patches are rectangular patches, and the width of the rectangular patches is 2 mm.

[0023] Furthermore, the width of the spiral patch is 5 mm, the interval between each spiral metal patch is 5 mm, the inner diameter of the metal is 5 mm, and the number of spiral layers is 4.

[0024] Furthermore, the width of the C-shaped patch is 10 mm, a 20 mm gap is provided between the C-shaped patches, a C-shaped patch energy dissipation component is provided at the gap, and the circumference of the unit component and the reflector is 165 mm.

[0025] Furthermore, the resistance of the energy dissipation component, ie, the resistor, on the outer closed-loop patch is 170 ohms, and the resistance of the energy dissipation component, ie, the resistor, on the connecting patch is 760 ohms.

[0026] Furthermore, the resistance of the C-shaped patch energy dissipation component is 400 ohms.

[0027] Furthermore, the thickness of the dielectric plate and the dielectric substrate is 1 mm, the thickness of the functional unit is 0.035 mm, and the distance between the unit element and the reflective plate is 165 mm.

[0028] The beneficial effect of the present invention is that the present invention works in the P-band. Since it adopts a three-dimensional vertical structure, although its implementation is more complicated than that of a traditional 2D plane and requires additional processing procedures, the unit size and thickness of the three-dimensional metamaterial absorber are smaller, and a more stable frequency response can be obtained, which can achieve better absorbing effects in the lower frequency bands of the P-band. In addition, since no magnetic materials are used, while ensuring a lower absorbing frequency band and a lower cross-section, it has the advantages of light weight and low cost, and is suitable for countering anti-stealth technologies such as low-frequency radar detection. In addition, since the thickness of the dielectric substrate of the absorbing structure is only 1 mm and the thickness of the metal plate is only 0.035 mm, the space between the dielectric substrate and the metal plate is filled with air or foam except for the cross metal structure. The structure has the advantage of flexibility and can conform to the curved surface, making it suitable for absorbing the curved surface of the turntable.

[0029] Based on the theory of electromagnetic metamaterials, the wave-absorbing structure was designed using electromagnetic resonance characteristics and the mechanism of electromagnetic induction. The present invention is located in a plane. When electromagnetic waves of different modes are incident, according to the mechanism of electromagnetic induction, the changing magnetic field will generate a circular induced electric field and further generate an induced current. By loading a concentrated resistor, the energy of the electromagnetic wave can be converted into heat energy, thereby achieving the absorption of electromagnetic waves. The electromagnetic waves are absorbed through the oscillation consumption of the spiral structure, achieving a reduction in cross-section and a further reduction in the operating frequency band. At the same time, the processing cost is reduced due to the reduction in the use of lumped resistors. In addition, compared with the structure that uses magnetic materials and uses magnetic loss to achieve wave absorption, this structure uses lumped resistors to achieve wave absorption performance by using electrical loss characteristics.

[0030] The low-cost ultra-low frequency lightweight absorbing structure based on metamaterials in the present invention mainly operates in the P band, and can achieve good low-frequency band absorbing performance from 155MHz-167MHz and from 200MHz-320MHz, realizing the purpose of electromagnetic stealth. While ensuring a low profile and light weight, it has the advantages of good ultra-low frequency band absorbing performance and stable structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of the explosion structure of the present invention, rectangular coordinate system xyz Representing spatial relationships;

[0032] Figure 2 This is a schematic diagram of the structure of the unit element 10 of the present invention, with a rectangular coordinate system xyzRepresenting spatial relationships;

[0033] Figure 3 1 is a schematic top view of the structure of the unit element 10 of the present invention;

[0034] Figure 4 It is a schematic structural diagram of the vertical unit I of the present invention;

[0035] Figure 5 In the high-frequency electromagnetic full-wave simulation software CST, when the TE wave and TM wave are incident on the structure of the present invention, the reflection coefficient S that varies with frequency is obtained. 11 Simulation results; TE wave (i.e. s wave): has a magnetic field component but no electric field component in the propagation direction, which is called a transverse electric wave; TM wave (i.e. p wave): has an electric field component but no magnetic field component in the propagation direction, which is called a transverse magnetic wave.

[0036] In the figure, 10 units, 20 vertical units I, 30 vertical units II, 40 partitioning dielectric plates, 50 reflective plates;

[0037] 11 dielectric board, 12 functional unit, 19 energy dissipation component;

[0038] 13 outer closed-loop patch, 14 middle closed-loop patch, 15 inner closed-loop patch, 16 inner concave patch, 17 connecting patch, 18 end-sealing patch;

[0039] 21 dielectric substrate, 22 C-shaped patch, 23 C-shaped patch energy dissipation component, 24 spiral patch. DETAILED DESCRIPTION

[0040] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0041] A metamaterial-based three-dimensional vertical P-band low-frequency absorbing structure includes multiple periodically arranged base structures, each of which includes a stacked reflector plate 50 and a separator plate 40. A cross-symmetrical vertical unit is provided on the separator plate 40. Each cross-symmetrical vertical unit is provided with a unit element 10. The unit element 10 includes a dielectric plate 11 and a functional unit provided on the dielectric plate 11.

[0042] The cross-symmetrical vertical unit includes a cross dielectric substrate composed of two vertical units intersecting in a cross shape, and a metal layer located on the cross dielectric substrate. The vertical unit includes a dielectric substrate 21, on which a C-shaped patch 22 and a spiral patch 24 located inside the C-shaped patch 22 are provided. The C-shaped patch 22 is provided with a C-shaped patch energy dissipation component 23. The cross dielectric substrate divides the space into four quadrants. The C-shaped patches 22 located on the surfaces of the two vertical units in each quadrant are connected, and the spiral patches 24 located on the surfaces of the two vertical units in each quadrant are connected.

[0043] The functional unit includes an outer closed-loop patch 13 and an inner closed-loop patch 15 located inside the outer closed-loop patch 13. The outer closed-loop patch 13 has at least two protruding corners, and a concave area is provided between the protruding corners. A connecting patch 17 is connected between the concave area and the inner closed-loop patch 15. A middle closed-loop patch 14 is also provided inside the protruding corners. Energy-consuming parts 19 are provided on the outer closed-loop patch 13 and / or the connecting patch 17.

[0044] The closed-loop patch refers to a structure that is itself a closed loop, and the patch refers to a strip made of a conductive material (such as metal, which can be copper); the protruding corner refers to the part that protrudes from the outer closed-loop patch. Since it protrudes from the outer closed-loop patch, there is a concave area between the protruding corners. The protruding corners and the concave area are both distinguished relative to the center of the outer closed-loop patch, that is, the protruding corners are farther away from the center of the outer closed-loop patch than the concave area.

[0045] The cross dielectric substrate is a vertical unit in xoy In-plane winding z The center of the cross dielectric substrate is the center of the unit element, the reflector 50 and the separation dielectric plate 40, which can achieve full polarization characteristics with stable transmission performance when irradiated by various polarized electromagnetic waves.

[0046] The C-shaped patch 22 is in the shape of a rectangle with one side missing, and the spiral patch is a series of straight line segments extending outward in a spiral from a center point, with adjacent straight line segments being perpendicular to each other.

[0047] The reflective plate 22 is a metal plate, the functional unit 12 is made of metal material, and the energy dissipation component 19 is a resistor.

[0048] The end of the connecting patch 17 is located inside the inner closed-loop patch 15 .

[0049] A sealing patch 18 is provided at the end of the connecting patch 17 .

[0050] The protruding angles are evenly distributed around the center point of the functional unit 12 , and the center of the inner closed-loop patch 15 is the center point of the functional unit 12 .

[0051] The protruding corner is in an arc shape, the middle closed-loop patch 14 is circular, and the inner closed-loop patch 15 is rectangular.

[0052] The protruding corner is in the shape of a 3 / 4 circular ring, and the inner closed-loop patch 15 is in the shape of a square.

[0053] The number of the protruding corners is four, the number of the middle closed-loop patches 14 is four, and the number of the connecting patches 17 is four.

[0054] The energy consuming parts 19 are evenly distributed around the center point of the functional unit 12 .

[0055] The middle closed-loop patch 14 is not connected to the outer closed-loop patch 13 or the inner closed-loop patch 15 .

[0056] Specifically, such as Figure 2-3 As shown, the unit element 10 is a square, and the unit element 10 includes a dielectric plate 11, a functional unit 12 attached to the upper surface of the dielectric plate 11, and an energy dissipation component 19, which is a resistor;

[0057] The functional unit 12 can be obtained by etching on the metal foil layer.

[0058] like Figure 2 As shown, the functional unit 12 is composed of an outer closed-loop patch 13, a middle closed-loop patch 14, an inner closed-loop patch 15, and a combined shape of a concave patch 16, a connecting patch 17 and a sealing patch 18 formed after etching on a metal foil; the outer closed-loop patch 13 is composed of four identical 3 / 4 circular patches in a symmetrical form; the middle closed-loop patch 14 is composed of four identical circular patches in a symmetrical form; the concave patch 16, the connecting patch 17 and the sealing patch 18 have three different sizes and are respectively composed of four identical rectangular patches in a symmetrical form; the resistor includes a first resistor and a second resistor; the first resistor and the second resistor are respectively composed of four identical resistors in a symmetrical form.

[0059] The centers of the outer closed-loop patch 13 and the middle closed-loop patch 14 coincide with each other; the center of the inner closed-loop patch 15 coincides with the center of the functional unit 12;

[0060] The length of the concave patch 16 is 8 mm, the length of the connecting patch 17 is 26 mm, and the length of the end-sealing patch 18 is 4 mm. All patches are rectangular patches with a width of 2 mm.

[0061] The resistance of the energy dissipation component, ie, the resistor, on the outer closed-loop patch 13 is 170 ohms, and the resistance of the energy dissipation component, ie, the resistor, on the connecting patch 17 is 760 ohms.

[0062] The resistance of the C-shaped patch energy dissipation component 23 is 400 ohms.

[0063] like Figure 4 As shown, the vertical unit I 20 and the vertical unit II 30 are the same, both including a dielectric substrate 21, a spiral patch 24 and a C-shaped patch 22 attached to the upper surface of the dielectric substrate 21, a spiral patch 24 attached to the lower surface of the dielectric substrate 21, and a C-shaped patch energy dissipation component 23 embedded in the C-shaped patch 22;

[0064] The width of the spiral patch 24 is 5 mm, the interval between each spiral metal patch is 5 mm, the inner diameter of the metal is 5 mm, and the number of spiral layers is 4;

[0065] The width of the C-shaped patch 22 is 10 mm. A 20 mm gap is provided between the C-shaped patches 22. The C-shaped patch energy dissipation component 23 is provided at the gap. The circumference of the unit element 10 and the reflector 50 is 165 mm.

[0066] The non-conductive material used to make the dielectric substrate is F4BTMS430, a product of Taizhou Wangling Insulation Material Factory, with a relative dielectric constant of 4.30 and a dielectric loss of 0.0015. The metal foil layer can be made of any of the metal foils, gold foil, silver foil, or copper foil.

[0067] In the high-frequency electromagnetic full-wave simulation software CST, when TE wave and TM wave are incident on the electromagnetic model, the reflection coefficient S that varies with frequency is obtained. 11 The simulation results, such as Figure 5 As shown. -10 The following reflection coefficient bands are from 155MHz to 167MHz and 200MHz-320MHz, and a strong resonance point appears in the range of 100MHz-300MHz, achieving a major breakthrough in ultra-low frequency band absorption performance. Due to the high symmetry of the absorbing structure, Figure 5 It can be seen from the figure that under the normal incidence of any polarized wave, the structure has no effect on the absorption performance and is insensitive to the polarization mode. At the same time, it achieves excellent absorption performance in the ultra-low frequency band.

[0068] It should be noted that the present invention is not limited to the above specific embodiments, and any modification or improvement made by those skilled in the art within the scope of protection of the claims shall fall within the scope of protection of the present invention.

[0069] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of protection of the present application is limited to these examples. In line with the present application, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of different aspects of one or more embodiments of the present application as described above, which are not provided in detail for the sake of simplicity.

[0070] The one or more embodiments of this application are intended to encompass all such substitutions, modifications, and variations that fall within the broad scope of this application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of one or more embodiments of this application should be included in the scope of protection of this application.

Claims

1. A three-dimensional vertical P-band low-frequency absorbing structure based on metamaterials, characterized by: The invention comprises a plurality of periodically arranged basic structures, wherein the basic structures comprise stacked and connected reflection plates (50) and separation medium plates (40), wherein a cross-symmetrical vertical unit is provided on the separation medium plate (40), wherein a unit element (10) is provided on the cross-symmetrical vertical unit, and wherein the unit element (10) comprises a medium plate (11) and a functional unit provided on the medium plate (11); The cross-symmetrical vertical unit comprises a cross dielectric substrate composed of two vertical units intersecting in a cross shape and a metal layer located on the cross dielectric substrate. The vertical unit comprises a dielectric substrate (21), a C-shaped patch (22) and a spiral patch (24) located inside the C-shaped patch (22) are provided on the dielectric substrate (21), and a C-shaped patch energy dissipation component (23) is provided on the C-shaped patch (22); the cross dielectric substrate divides the space into four quadrants, the C-shaped patches (22) located on the surfaces of the two vertical units in each quadrant are connected, and the spiral patches (24) located on the surfaces of the two vertical units in each quadrant are connected; The functional unit comprises an outer closed-loop patch (13) and an inner closed-loop patch (15) located inside the outer closed-loop patch (13); the outer closed-loop patch (13) has at least two protruding corners, a concave area is provided between the protruding corners, a connecting patch (17) is connected between the concave area and the inner closed-loop patch (15), a middle closed-loop patch (14) is further provided inside the protruding corners, and an energy-consuming part (19) is provided on the outer closed-loop patch (13) and / or the connecting patch (17).

2. The wave absorbing structure according to claim 1, wherein: The C-shaped patch (22) is in the shape of a rectangle with one side missing, and the spiral patch is a series of straight line segments extending outward in a spiral from a center point, with adjacent straight line segments being perpendicular.

3. The wave absorbing structure according to claim 1, wherein: The reflective plate (50) is a metal plate, the functional unit is made of a metal material, and the energy-consuming component (19) is a resistor.

4. The wave absorbing structure according to claim 1, wherein: The end of the connecting patch (17) is located inside the inner closed-loop patch (15); and a sealing patch (18) is provided at the end of the connecting patch (17).

5. The wave absorbing structure according to any one of claims 1 to 4, wherein: The protruding angles are evenly distributed with the center point of the functional unit as the center, and the center of the inner closed-loop patch (15) is the center point of the functional unit.

6. The wave absorbing structure according to any one of claims 1 to 4, wherein: The protruding corner is in an arc shape, the middle closed-loop patch (14) is circular, and the inner closed-loop patch (15) is rectangular.

7. The wave absorbing structure according to claim 6, wherein: The protruding corner is in the shape of a 3 / 4 circular ring, and the inner closed-loop patch (15) is in the shape of a square.

8. The wave absorbing structure according to any one of claims 1 to 4, wherein: The number of the protruding corners is four, the number of the middle closed-loop patches (14) is four, and the number of the connecting patches (17) is four.

9. The wave absorbing structure according to any one of claims 1 to 4, wherein: The energy-consuming parts (19) are evenly distributed around the center point of the functional unit.

10. The wave absorbing structure according to any one of claims 1 to 4, characterized in that: The middle closed-loop patch (14) is not connected to the outer closed-loop patch (13) or the inner closed-loop patch (15).

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