A water-based low-frequency metamaterial absorber

Abstract

The present invention belongs to the technical field of low-frequency metamaterial absorbers, and specifically relates to a water-based low-frequency metamaterial absorber. The water-based low-frequency metamaterial absorber comprises a plurality of centrosymmetrical structural units, each of which is composed, from top to bottom, of a top pattern, an upper dielectric layer, an intermediate dielectric layer, a lower dielectric layer, and a metal backing plate. The intermediate dielectric layer is made of water, and the top pattern, upper dielectric layer, lower dielectric layer, and metal backing plate have equal length and width dimensions, and are larger than the intermediate dielectric layer. The water-based low-frequency metamaterial absorber provided by the present invention has a simple structure and a small thickness, and can achieve an absorption rate of more than 90% in the 1-2 GHz range exceeding the 0.4 GHz bandwidth, and an absorption rate of more than 80% in the 0.6 GHz bandwidth exceeding the 0.6 GHz bandwidth.

Description

Technical Field

[0001] The present invention belongs to the technical field of low-frequency metamaterial absorbing materials, and in particular relates to a water-based low-frequency metamaterial absorbing body. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art.

[0003] Traditional absorbing materials are a class of materials used to reduce or eliminate electromagnetic wave reflections and are commonly used in electromagnetic stealth technology and wireless communication devices. The basic principle of these materials is to reduce reflection by absorbing the energy of incident electromagnetic waves, thereby reducing the detectability of target objects in the electromagnetic spectrum. The earliest traditional absorbing materials included ferrites and hydroxyl iron powders, which exhibited good absorption properties for electromagnetic waves in specific frequency bands. However, traditional absorbing materials have limited effectiveness in low-band and broadband applications because their absorbing properties are generally single and limited by frequency and angle.

[0004] The development of metamaterial absorbing technology stems from a need to address the limitations of traditional absorbing materials. The performance of traditional absorbing materials is constrained by frequency selectivity, sensitivity to incident angles, and thickness restrictions. Metamaterial absorbing technology has emerged as a response to these limitations. By designing metamaterial structural units, these limitations can be overcome, enabling more flexible and broader frequency absorption of electromagnetic waves. This technology has widespread applications in military, communications, radar, medical equipment, and other fields, providing new solutions for electromagnetic wave management and stealth technology.

[0005] Whether it is traditional absorbing materials or metamaterial absorbers, it is difficult to absorb low-frequency electromagnetic waves, especially the 1-2GHz electromagnetic wave frequency band, which mostly requires larger unit size and thickness. Summary of the Invention

[0006] In order to solve the problems that the current absorbing structure has a narrow low-frequency absorbing bandwidth, is difficult to cover the 1-2 GHz range, and is thick, the present invention provides a water-based low-frequency metamaterial absorber with a simple structure and small thickness. It can achieve an absorption rate of more than 90% in the 1-2 GHz range exceeding the 0.4 GHz bandwidth and an absorption rate of more than 80% in the 0.6 GHz bandwidth.

[0007] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0008] In a first aspect, the present invention provides a water-based low-frequency metamaterial absorber, comprising a plurality of centrosymmetrical structural units, wherein the structural units are composed of a top pattern, an upper dielectric layer, an intermediate dielectric layer, a lower dielectric layer and a metal backplane from top to bottom, and the material of the intermediate dielectric layer is water.

[0009] The beneficial effects achieved by one or more technical solutions of the present invention are as follows:

[0010] 1. Due to the temperature-controlled dielectric constant of water, the water-based low-frequency metamaterial absorber of the present invention can achieve an absorption rate of more than 90% in the 0.4 GHz bandwidth within the 1-2 GHz range and an absorption rate of more than 80% in the 0.6 GHz bandwidth.

[0011] 2. The water-based low-frequency metamaterial absorber of the present invention has a simple structure and a small thickness, with a minimum thickness of 12 mm.

[0012] 3. Since the structural unit is centrosymmetric, the water-based low-frequency metamaterial absorber exhibits the characteristic that the absorption rate is independent of the polarization angle and is insensitive to the incident angle and polarization.

[0013] 4. The absorption rate curve can be controlled by adjusting the structural parameters, laying the foundation for further practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0015] Figure 1 Schematic diagram of the structural unit of the water-based low-frequency metamaterial absorber of the present invention, wherein (a) is an overall effect diagram, (b) is a side view, and (c) is a front view;

[0016] Figure 2 This is a simulation result diagram of the change in absorptivity of the water-based low-frequency metamaterial absorber with temperature;

[0017] Figure 3 (a) shows the simulation results of the absorption rate of the water-based low-frequency metamaterial absorber at different incident angles, and (b) shows the simulation results of the absorption rate of the water-based low-frequency metamaterial absorber at different polarization angles.

[0018] Figure 4 This is a simulation result diagram showing the change in absorptivity of the water-based low-frequency metamaterial absorber with the resistance value of the resistor film according to the present invention;

[0019] Figure 5 This is a simulation result diagram of the absorption rate of the water-based low-frequency metamaterial absorber according to the present invention as h1 changes;

[0020] Figure 6 This is a simulation result diagram of the absorption rate of the water-based low-frequency metamaterial absorber according to the present invention as the absorption rate changes with different h2;

[0021] Figure 7 Graph showing the simulation results of the absorptivity of the water-based low-frequency metamaterial absorber in Example 1;

[0022] Figure 8 This is a diagram showing the absorptivity simulation results of the water-based low-frequency metamaterial absorber in Example 2;

[0023] Figure 9 This is a diagram showing the absorption rate simulation results of the water-based low-frequency metamaterial absorber in Example 3.

[0024] Among them, 1 is the metal patch, 2 is the square ring resistor film, 3 is the upper dielectric layer, 4 is the middle dielectric layer, 5 is the lower dielectric layer, 6 is the metal backplane, a is the side length of the metal patch, p is the structural unit period, h1 is the thickness of the upper dielectric layer, h2 is the thickness of the water in the middle dielectric layer, and h3 is the thickness of the lower dielectric layer. DETAILED DESCRIPTION

[0025] The first typical embodiment of the present invention is a water-based low-frequency metamaterial absorber, comprising a plurality of centrosymmetrical structural units, wherein the structural units are composed of a top pattern, an upper dielectric layer, an intermediate dielectric layer, a lower dielectric layer, and a metal backplane from top to bottom, wherein the material of the intermediate dielectric layer is water. Specifically, the structural units of the water-based low-frequency metamaterial absorber are as follows: Figure 1 shown.

[0026] Water, a common and abundant material in nature, possesses large real and imaginary dielectric constants, making it an excellent medium for storing and dissipating electromagnetic wave energy. Furthermore, low-frequency electromagnetic waves correspond to longer wavelengths, and materials with high dielectric constants require less thickness to achieve a quarter-wavelength. Therefore, water is expected to be an excellent medium for absorbing low-frequency electromagnetic waves. In 2007, W.J. Ellison published a paper on the dielectric constant of water. Through fitting analysis and theoretical verification of extensive experimental test data, he developed a computational model for the variation of the dielectric constant of water with temperature from 0 to 100°C within the 0-25 THz frequency band, demonstrating the correlation between the dielectric constant of water and operating frequency and temperature. Furthermore, the electromagnetic parameters of water are affected by temperature, enabling tunable absorption of electromagnetic waves in different bands through temperature control.

[0027] In one or more embodiments of this implementation mode, the length and width of the top pattern, the upper dielectric layer, the lower dielectric layer and the metal backplate are equal in size and larger than the middle dielectric layer; the top pattern is composed of a square ring-shaped resistor film and a square metal patch, the outer side length p of the square ring-shaped resistor film is 12.5 to 13 cm, the side length a of the square metal patch is 5.5 to 6 cm, and the side length of the square metal patch is equal to the inner side length of the square ring-shaped resistor film.

[0028] In one or more examples of this embodiment, the temperature of the intermediate dielectric layer is 10-90°C.

[0029] Due to the property that the dielectric constant of water is controlled by temperature, such as Figure 2 As shown, the water-based low-frequency metamaterial absorber can achieve an absorption rate of more than 90% in the 1-2 GHz range exceeding the 0.4 GHz bandwidth and an absorption rate of more than 80% in the 0.6 GHz bandwidth.

[0030] like Figure 3 As shown in (a), under the conditions of electromagnetic wave incident angles of 0 to 60°, the absorption band narrows and the absorption rate decreases, but the overall change is not significant, indicating that the incident angle stability of the water-based low-frequency metamaterial absorber is good; Figure 3 As shown in (b), the absorption curves at polarization angles of 0 to 90° are completely overlapped, indicating that the designed water-based low-frequency broadband absorber is insensitive to electromagnetic waves incident at polarization angles of 0 to 90°. This is because the structural unit is centrosymmetric, so the absorption rate shows the characteristic of being independent of the polarization angle.

[0031] In one or more embodiments of this embodiment, the resistance of the resistor film is 245 to 500Ω. Figure 4 As shown in the figure, with the increase of the resistance value R of the resistor film, the position of the absorption peak moves slightly to the high frequency, and the absorption rate and absorption bandwidth do not change significantly.

[0032] In one or more examples of this embodiment, the top pattern and the metal back plate are made of copper with a thickness of 0.015-0.02 mm.

[0033] In one or more examples of this implementation manner, the thickness h1 of the upper dielectric layer is 1 to 3 mm.

[0034] In one or more examples of this implementation manner, the thickness h2 of the intermediate dielectric layer is 8 to 14 mm.

[0035] The results of the change of absorption rate with h1 are as follows Figure 5 As shown in the figure, the absorption rate of h1 in the range of 1-3mm at 1-2GHz basically does not change, and the thickness of the upper dielectric layer has little effect on the absorption effect. Figure 6 As shown, the absorptivity curve changes significantly with changes in h2. Within the 8-14 mm range, as h2 increases, the absorption peak gradually shifts to lower frequencies, and the absorption bandwidth gradually narrows. The reason h2 causes a larger change in the absorptivity curve compared to h1 is its higher dielectric constant, which is more pronounced for the quarter-wavelength principle.

[0036] In one or more examples of this implementation manner, the thickness h3 of the lower dielectric layer is 2.9-3.1 mm.

[0037] In one or more embodiments of this embodiment, the material of the upper dielectric layer is FR4, with a relative dielectric constant ε r =4.3, loss tangent tanθ=0.025.

[0038] In one or more embodiments of this embodiment, the lower dielectric layer is made of Arlon AD 250C, with a relative dielectric constant ε r =2.5, loss tangent tanθ=0.0013.

[0039] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments and comparative examples.

[0040] Example 1

[0041] like Figure 1 As shown, the structural unit of the water-based low-frequency metamaterial absorber consists of a top pattern, three dielectric layers and a metal backplane 6, wherein the top pattern is composed of a square ring resistor film 2 and a square metal patch 1. The upper dielectric layer 3 is made of FR4 with a relative dielectric constant ε r =4.3, loss tangent tanθ = 0.025. The material used for the middle dielectric layer 4 is water, and the initial temperature during simulation is 10°C. The material used for the lower dielectric layer 5 is Arlon AD 250C, with a relative dielectric constant ε r =2.5, loss tangent tanθ = 0.0013. The metal patch 1 and the metal back plate 6 are made of copper, whose conductivity is σ = 5.96×10 7S / m, and the thickness of the copper layer is 0.018mm. The resistance of resistor film 2 is R = 300Ω. The specific geometric parameters are: p = 12.8mm, a = 5.8mm, h1 = 1.9mm, h2 = 12mm, h3 = 3mm, and the total thickness is 16.9mm. This structural unit is simulated using CST electromagnetic simulation software. During the simulation, the unit cell boundary conditions are used in the x and y directions to simulate the infinite plate in real conditions. The positive direction of the z axis is open to simulate the open boundary of free space. The electromagnetic wave excitation is incident on the model surface from the positive direction of z. The frequency domain solver is used to calculate the cases of electromagnetic wave incident at 0° incident angle and 0° polarization angle.

[0042] The simulation results are as follows Figure 7 As shown, the bandwidth with an absorption rate of 90% or more is 1.24-1.65 GHz, totaling 0.42 GHz, and the frequency band with an absorption rate of 80% or more is 1.15-1.75 GHz, totaling 0.61 GHz.

[0043] Example 2

[0044] like Figure 1 As shown, the structural unit of the water-based low-frequency metamaterial absorber consists of a top pattern, three dielectric layers and a metal backplane 6, wherein the top pattern is composed of a square ring resistor film 2 and a square metal patch 1. The upper dielectric layer 3 is made of FR4 with a relative dielectric constant ε r =4.3, loss tangent tanθ = 0.025. The material used for the middle dielectric layer 4 is water, and the initial temperature during simulation is 10°C. The material used for the lower dielectric layer 5 is Arlon AD 250C, with a relative dielectric constant ε r =2.5, loss tangent tanθ = 0.0013. The metal patch 1 and the metal back plate 6 are made of copper, whose conductivity is σ = 5.96×10 7 S / m, and the thickness of the copper layer is 0.018mm. The resistance of resistor film 2 is R = 400Ω. The specific geometric parameters are: p = 12.8mm, a = 5.8mm, h1 = 1.0mm, h2 = 9mm, and h3 = 3mm. This structural unit is simulated using CST electromagnetic simulation software. During the simulation, the unit cell boundary conditions are used in the x and y directions to simulate the infinite plate in real conditions. The positive direction of the z axis is open to simulate the open boundary of free space. The electromagnetic wave excitation is incident on the model surface from the positive direction of z. The frequency domain solver is used to calculate the cases of electromagnetic wave incident at 0° incident angle and 0° polarization angle.

[0045] The simulation results are as follows Figure 8As shown, the bandwidth with an absorption rate of 90% or more is 1.56-1.96 GHz, totaling 0.41 GHz, and the frequency band with an absorption rate of 80% or more is 1.46-2.06 GHz, totaling 0.61 GHz.

[0046] Example 3

[0047] like Figure 1 As shown, the structural unit of the water-based low-frequency metamaterial absorber consists of a top pattern, three dielectric layers and a metal backplane 6, wherein the top pattern is composed of a square ring resistor film 2 and a square metal patch 1. The upper dielectric layer 3 is made of FR4 with a relative dielectric constant ε r =4.3, loss tangent tanθ=0.025. The material used for the middle dielectric layer 4 is water, and the initial temperature during simulation is 60°C. The material used for the lower dielectric layer 5 is Arlon AD 250C, with a relative dielectric constant ε r =2.5, loss tangent tanθ = 0.0013. The metal patch 1 and the metal back plate 6 are made of copper, whose conductivity is σ = 5.96×10 7 S / m, and the thickness of the copper layer is 0.018mm. The resistance of resistor film 2 is R = 500Ω. The specific geometric parameters are: p = 12.8mm, a = 5.8mm, h1 = 3mm, h2 = 11mm, h3 = 3mm, and the total thickness is 16.9mm. This structural unit is simulated using CST electromagnetic simulation software. During the simulation, the unit cell boundary conditions are used in the x and y directions to simulate the infinite plate in real conditions. The positive direction of the z axis is open to simulate the open boundary of free space. The electromagnetic wave excitation is incident on the model surface from the positive direction of z. The frequency domain solver is used to calculate the cases of electromagnetic wave incident at 0° incident angle and 0° polarization angle.

[0048] The simulation results are as follows Figure 9 As shown, the bandwidth with an absorption rate of 90% or more is 1.42-1.87 GHz, totaling 0.46 GHz, and the frequency band with an absorption rate of 80% or more is 1.31-1.97 GHz, totaling 0.67 GHz.

[0049] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A water-based low-frequency metamaterial absorber, characterized in that: The invention comprises a plurality of centrosymmetrical structural units, wherein the structural units are composed of a top pattern, an upper dielectric layer, an intermediate dielectric layer, a lower dielectric layer and a metal back plate from top to bottom, and the material of the intermediate dielectric layer is water; The length and width of the top pattern, upper dielectric layer, lower dielectric layer and metal backplate are equal and larger than the middle dielectric layer; the top pattern is composed of a square ring-shaped resistive film and a square metal patch, the outer side length p of the square ring-shaped resistive film is 12.5~13 cm, the side length a of the square metal patch is 5.5~6 cm, and the side length of the square metal patch is equal to the inner side length of the square ring-shaped resistive film.

2. The water-based low-frequency metamaterial absorber according to claim 1, characterized in that: The resistance of the resistor film is 245-500 Ω.

3. The water-based low-frequency metamaterial absorber according to claim 1, wherein: The metal back plate is made of copper and has a thickness of 0.015-0.02 mm.

4. The water-based low-frequency metamaterial absorber according to claim 1, wherein: The temperature of the middle dielectric layer is 10~90 ℃.

5. The water-based low-frequency metamaterial absorber according to claim 1, characterized in that: The thickness h1 of the upper dielectric layer is 1-3 mm.

6. The water-based low-frequency metamaterial absorber according to claim 1, wherein: The thickness h2 of the intermediate dielectric layer is 8-14 mm.

7. The water-based low-frequency metamaterial absorber according to claim 1, wherein: The thickness h3 of the lower dielectric layer is 2.9-3.1 mm.

8. The water-based low-frequency metamaterial absorber according to claim 1, wherein: The material of the upper dielectric layer is FR4, with a relative dielectric constant ε r =4.3, loss tangent tanθ=0.

025.

9. The water-based low-frequency metamaterial absorber according to claim 1, wherein: The lower dielectric layer is made of Arlon AD 250C with a relative dielectric constant of ε r =2.5, loss tangent tanθ=0.0013.

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