Water-metal hybrid metamaterial absorber and its applications
By designing a water-metal hybrid metamaterial absorber, the design problem of low-frequency absorbers has been solved, and perfect absorption and frequency regulation of three frequency points have been achieved. It is suitable for the fields of electromagnetic shielding and absorption. The materials are easy to obtain and low-cost.
Patent Information
- Application Number
- CN202411258178.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-09
- Publication Date
- 2025-09-26
- Estimated Expiration
- 2044-09-09
AI Technical Summary
Existing low-frequency electromagnetic metamaterial absorbers face challenges in design and manufacturing, making it difficult to achieve good absorbing performance. In addition, there is little research on water-based metamaterials in the low-frequency band, resulting in their application value not being fully utilized.
A water-metal hybrid metamaterial absorber is designed. The structural unit consists of a metal base plate, an air layer, a dielectric plate, a metal pattern layer and a water layer. The frequency range and efficiency can be controlled in real time by adjusting the thickness of the air layer. Conventional materials are used to reduce costs.
It achieves near-perfect absorption of three frequency points in the low-frequency band of 0-1GHz, has a miniaturized design and good wave-absorbing effect, is suitable for a variety of application scenarios, and the materials are easy to obtain and low-cost.
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Figure CN119181983B_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of electromagnetic metamaterials and relates to a water-metal hybrid metamaterial absorber and applications thereof. Background Art
[0002] The microwave band is an integral part of the vast electromagnetic spectrum, spanning 300MHz to 300GHz. Researchers typically focus on the low-frequency portion of the microwave band, typically between 300MHz and 3GHz. Low-frequency electromagnetic waves possess the characteristics of large wavelengths, strong penetration, wide coverage, and low propagation loss. These exceptional properties make them extremely valuable in a variety of applications, including wireless communications, radar detection, and electromagnetic stealth.
[0003] The widespread use of low-frequency electromagnetic waves, while providing numerous benefits, also carries with it potential hazards that should not be ignored. Long-term exposure to electromagnetic environments poses threats to the environment and human health, and can also cause electromagnetic interference, disrupting the normal operation of equipment. Therefore, low-frequency electromagnetic shielding technology has emerged as a key solution to these problems. Low-frequency electromagnetic shielding technology has a wide range of applications. In the communications field, it can be used to protect communication equipment from external electromagnetic interference, ensuring stable and reliable communications. In the military, low-frequency electromagnetic shielding technology is often used in electromagnetic stealth technology, reducing the risk of detection by enemy radar. It can also be used to design stealth communication equipment to ensure the security of military communications. In the medical field, low-frequency electromagnetic shielding technology can protect medical equipment from electromagnetic interference, ensuring the normal operation of medical equipment and the safety of patients.
[0004] Metamaterials are man-made composite materials with extraordinary physical properties. Due to their unique electromagnetic properties, metamaterials have been widely studied in areas such as negative refractive index, polarization conversion, stealth technology, and electromagnetic wave absorption. Perfect electromagnetic wave absorption has become a hot topic in the metamaterials field. Most existing electromagnetic metamaterial absorbers typically consist of a multilayer structure consisting of a metal pattern, a dielectric plate, and a metal backplane. They absorb electromagnetic waves by converting electromagnetic wave energy into other forms of energy through magnetic, dielectric, or ohmic losses. With in-depth research on electromagnetic metamaterial absorbers, many promising metamaterial absorbers have emerged in the microwave and even terahertz bands. However, at low frequencies, the excessively large wavelengths pose significant challenges in setting the electromagnetic parameters and controlling the dimensions of the absorber, making it difficult to achieve good absorption performance in the designed metamaterial absorber and making its realization more challenging. In recent years, research on water-based metamaterials in the field of electromagnetic absorbers has attracted widespread attention. Water offers advantages such as cleanliness, easy regeneration, low cost, and stable chemical properties. At microwave frequencies, water has a high dielectric constant and exhibits strong frequency dispersion, resulting in high dielectric loss for electromagnetic waves across a wide frequency band, facilitating broadband absorption in the microwave range. However, research on water-based metamaterial absorbers at low frequencies is relatively limited, but their potential applications cannot be ignored. Summary of the Invention
[0005] The present invention provides a water-metal hybrid metamaterial absorber and its application. The absorber can realize absorption of three frequency points at low frequencies of 0-1 GHz, and also has the real-time regulation function of the operating frequency range and efficiency.
[0006] To achieve the above objectives, the present invention adopts the following technical solution: a water-metal hybrid metamaterial absorber, which includes multiple periodically arranged structural units. The structural units are rectangular and, from bottom to top, are a metal base plate layer, an air layer, a dielectric plate layer, a metal pattern layer, and a water layer. A plexiglass layer is provided above the water layer, and a plexiglass layer is provided between the air layer and the dielectric plate layer.
[0007] Furthermore, the length of the structural unit is 59-60 mm, the width is 29-30 mm, and the thickness is 12.40-12.50 mm.
[0008] Furthermore, the metal bottom plate layer is made of copper material with a thickness of 0.025mm~0.035mm.
[0009] Furthermore, the thickness of the air layer is 1-1.2 mm.
[0010] Furthermore, the dielectric board layer is FR4, with a dielectric constant of 4.2-4.3 and a thickness of 1-1.2 mm.
[0011] Furthermore, the thickness of the water layer is 8.0 mm to 8.6 mm.
[0012] Furthermore, the metal pattern layer is located on the upper surface of the dielectric plate layer and is an axially symmetrical or centrally symmetrical figure; the metal pattern layer includes two semicircles, a slit circular ring between the two semicircles, and a cross structure composed of two rectangles of the same length and width perpendicular to each other within the slit circular ring; the center of the semicircle is located at the center of the wide side of the dielectric plate layer, the center of the slit circular ring coincides with the center of the cross, and the slit circular ring is provided with two slits, which are perpendicular to the long side direction of the dielectric plate layer.
[0013] Furthermore, the metal pattern layer is made of copper material, with a thickness of 0.025 mm to 0.035 mm and a width of 2.8 mm to 3 mm.
[0014] Furthermore, the radius of the semicircle is 13.5~14mm; the inner diameter and outer diameter of the slit ring are 11.5~12mm and 14.5~15mm respectively, and the slit width is 2.8~3mm; the length and width of the rectangle constituting the cross structure are 13.5~14mm and 2.8~3mm respectively.
[0015] The present invention also relates to the application of the water-metal hybrid metamaterial absorber in the fields of electromagnetic absorption and electromagnetic shielding.
[0016] The present invention has the following beneficial effects:
[0017] 1. This water-metal hybrid metamaterial absorber achieves near-perfect absorption at three frequencies (0.45 GHz, 0.65 GHz, and 0.95 GHz) in the low-frequency range of 0-1 GHz. Measuring 60 x 30 mm, this absorber offers the same performance as similar absorbers, yet boasts a smaller size and simpler structure. This absorber combines a simple, compact design with excellent low-frequency absorption.
[0018] 2. The present invention achieves regular regulation of the operating frequency range and efficiency of the absorber by changing the thickness of the air layer, has better practical application value, and can be applied to more application scenarios.
[0019] 3. The materials used in the present invention are all conventional materials and are easy to implement. In addition, the structure of the present invention is loaded with water materials, which are easy to obtain and have a lower cost. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 (a), (b) and (c) are respectively a unit structure diagram, a side view of the unit structure and a top view of the metal pattern layer of the water-metal hybrid metamaterial absorber of Example 1.
[0021] Figure 2 1 is a diagram showing the overall structure of the water-metal hybrid metamaterial absorber of Example 1.
[0022] Figure 3 This is a graph showing the absorption rate of the water-metal hybrid metamaterial absorber according to Example 2 with different structures removed.
[0023] Figure 4 This is a graph showing the absorption rate of the water-metal hybrid metamaterial absorber of Example 3 at different polarization angles.
[0024] Figure 5 This is a graph showing the absorption rate of the water-metal hybrid metamaterial absorber of Example 3 at different incident angles.
[0025] Figure 6 4 is a graph showing the variation of the absorption rate of the water-metal hybrid metamaterial absorber according to Example 4 with the thickness d2 of the water layer.
[0026] Figure 7 (a) and (b) are respectively a schematic diagram of the rotation of the slotted ring in the water-metal hybrid metamaterial absorber of Example 5 and a curve diagram of the change of the absorption rate with the rotation angle Φ.
[0027] Figure 8 This is a curve diagram of the absorption rate of the water-metal hybrid metamaterial absorber of Example 6 as a function of the air layer thickness d4.
[0028] Figure 9 This is a graph showing absorption rates of the water-metal hybrid metamaterial absorber in Example 7 with different structures removed from the metal pattern layer. DETAILED DESCRIPTION
[0029] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.
[0030] Example 1
[0031] The unit structure of the water-metal hybrid metamaterial absorber model provided in this embodiment is as follows: Figure 1 As shown in (a), the internal structure of the unit is a rectangular parallelepiped consisting of a water layer, a metal pattern layer, an FR4 dielectric layer, an air layer, and a metal base plate at the back. Due to the fluid properties of water, the water layer and the dielectric layer are wrapped with organic glass to prevent water leakage. The side view of the unit structure is shown in Figure 1 As shown in (b), the thickness of the organic glass layer is d1 = 1mm. The thickness of the water layer composed of water (Debye model) is d2 = 8.4mm, and the relative dielectric constant of the dielectric layer FR4 below is , the tangent of the loss angle is , the thickness is d3 = 1mm, the thickness of the air layer below the dielectric plate is d4 = 1mm, the bottom metal plate and the metal pattern layer above the dielectric plate are made of The metal pattern layer is made of copper with a corresponding thickness of 0.035 mm. Figure 1 As shown in (c), the left and right parts are two symmetrical semicircles, and the middle part consists of a slit ring and a cross structure. The width of the ring slit is the same as the width of the cross strip. Other structural parameters are: w=12mm, k=3mm, W=14mm, R=15mm, r=12mm, and the overall length and width of the model are p=60mm and q=30mm. When multiple unit structures are arranged closely and periodically, the overall structure is shown as follows. Figure 2 shown.
[0032] Example 2
[0033] The metamaterial absorber of the present invention is composed of a water-metal hybrid material. Its multi-frequency and high absorption performance is related to the characteristics of the metal pattern layer and the water layer. In order to better analyze the influence of different structures in the absorber on the absorption characteristics, the metal layer and the water layer were removed and compared with the designed structure. The simulation results are shown in the figure below. Figure 3 As shown, structure 1 retains the metal layer and the water layer, structure 2 retains the water layer and removes the metal layer, and structure 3 retains the metal layer and removes the water layer. Figure 2 It can be seen that when the water layer is removed, the absorber has almost no absorption effect on electromagnetic waves. At the same time, due to the presence of the metal bottom plate, the whole is in a state of total reflection, which shows that the presence of the water layer is crucial to the absorption effect. When the metal pattern layer is removed, there is only one absorption frequency point of 0.71GHz in the low frequency band, and the absorption rate is far from reaching 90%, which shows that there is a close connection between the metal structure and the wave absorbing characteristics. When the water layer and the metal structure are combined to form Figure 1 When the structure is shown, the corresponding absorption curve is as follows Figure 3As shown, absorption peaks are present at 0.45 GHz, 0.65 GHz, and 0.95 GHz, with absorption rates reaching 97.4%, 98.1%, and 98.3%, respectively, achieving near-perfect absorption at these three low-frequency frequencies. Because direct contact between water and copper metal can cause corrosion, consideration was given to encapsulating the metal pattern layer with a material to prevent direct contact between the metal and water. Based on these considerations, the selected material needed to meet corrosion resistance, transparency to low-frequency electromagnetic waves, and compatibility with copper. PTFE was chosen to encapsulate the metal pattern layer to prevent corrosion. PTFE (polytetrafluoroethylene film) has a low dielectric constant and dielectric loss, providing excellent transmittance for low-frequency electromagnetic waves. Compared to high-frequency electromagnetic waves, low-frequency electromagnetic waves are less reflected and absorbed by PTFE. PTFE also possesses strong corrosion resistance, withstanding erosion by a variety of corrosive media, including strong acids, strong bases, and organic solvents, and performs exceptionally well in aqueous environments.
[0034] Example 3
[0035] In order to study the functional mechanism of the water-metal hybrid metamaterial absorber of the present invention, the absorption frequency and absorptivity under different incident angles and polarization angles were studied. When electromagnetic waves are incident at different polarization angles, the corresponding absorption spectra are as follows: Figure 4 As shown in Figure 2, at the first resonant frequency point, when the polarization angle is less than 30°, the resonant frequency and absorption rate basically do not change. When the polarization angle increases, the resonant frequency does not change, and the absorption rate decreases by about 10%. The second resonant frequency gradually moves toward the low frequency direction as the polarization angle increases. The decrease in the absorption rate with the change in polarization angle can be ignored. At this point, the absorption effect is the worst at 97.0%, and the curve with an absorption rate greater than 90% becomes flat, and the absorption bandwidth becomes wider. The third resonant frequency undergoes subtle changes with increasing polarization angle. When the polarization angle is less than 45°, the absorption rate at the resonant frequency remains unchanged. When the polarization angle reaches 45°, the absorption rate drops sharply, approaching 83%, and a new absorption frequency appears at 1.12 GHz. As can be seen from the above, when the polarization angle is less than 30°, the absorber's absorption characteristics change slightly with the polarization angle. When the polarization angle exceeds 30°, the absorber's absorption effect undergoes a significant change, indicating that the absorber is polarization-sensitive. Figure 5The absorption curves of the designed metamaterial at different incident angles are shown in the figure. As the incident angle varies between 0 and 60°, the frequencies of the three resonant frequencies remain essentially unchanged, but the overall absorption rate shows a downward trend. At an incident angle of 60°, the model's absorption performance is the worst, with resonant frequencies at 0.45 GHz, 0.65 GHz, and 0.94 GHz, corresponding to absorption rates of 96.0%, 95.0%, and 95.4%, respectively. Compared to normal incidence, the absorption rate at each resonant frequency decreases, with the second frequency experiencing the largest decrease, by 3.1%. However, the overall decrease is small, and the absorption performance remains strong even after the decrease. As shown above, the absorber maintains excellent absorption performance for obliquely incident electromagnetic waves at the corresponding frequencies, and the effect of changes in the incident angle on the absorber's absorption properties is negligible, demonstrating the absorber's wide-angle absorption characteristics.
[0036] Example 4
[0037] The simulation test was carried out by CST simulation software. In order to obtain the optimal structural parameters, the structural parameters were studied by using the parameter scanning analysis method based on the control variable method. First, the effect of the water layer thickness on the absorption frequency and absorption rate was studied. Figure 6 As shown in the figure, when d2 = 7.4mm, the absorption rates of the three resonant points all reach over 99%, which is an extremely high absorption rate, but the frequency of the third frequency point exceeds the ideal operating frequency range (1GHz). When d2 = 8.4mm, the three resonant frequencies are all within 1GHz, and the absorption rates all reach over 97%. The absorption frequency points are in the low frequency band while ensuring good absorption rates. When d2 = 10.4mm, compared with d2 = 8.4mm, the three resonant frequencies are basically unchanged, and the maximum reduction in absorption rate at the resonant frequency points is only 1%. Considering that miniaturized metamaterial absorbers in the low frequency band can better adapt to practical applications, a thinner water layer thickness is selected when the absorption characteristics are basically the same. At the same time, in order to achieve the operating frequency range below 1GHz, a water layer thickness of 8.4mm is selected as the model size.
[0038] Example 5
[0039] Study on the effect of the rotation angle of the slotted ring on the absorption frequency and absorption rate of the metamaterial absorber
[0040] Keep the structure and parameters of other layers unchanged, and only adjust the angle of the slit ring. The specific angles are 30°, 60°, and 90°. The metal layer pattern after rotation is as follows Figure 7 As shown in (a), an asymmetric metal structure is obtained, and then the absorption rate at different rotation angles is simulated. The simulation results are shown in Figure 7 (b) is shown. Figure 7(b) shows that the resonant frequency of the first absorption frequency point shifts greatly with the increase of the rotation angle. Compared with the rotation angle of 0°, the absorption rate after rotation decreases significantly, and the absorption effect of more than 90% cannot be guaranteed. At the second absorption frequency point, when the rotation angle is less than 90°, the resonant frequency moves toward the low-frequency direction, and the absorption rate shows a slight upward trend, reaching 99% when rotated 60°. When the rotation angle is equal to 90°, the resonant frequency moves toward the high-frequency direction, and the absorption rate remains basically unchanged. At the third absorption frequency point, when the rotation angle is 30°, the resonant frequency moves toward the low-frequency direction, and the absorption rate shows an upward trend. When the rotation angle is 60°, the resonant frequency moves toward the high-frequency direction, and the absorption rate shows an upward trend. When the rotation angle is 90°, the changes in the resonant frequency and absorption rate are very weak compared to 0°. From the above, it can be seen that when the slit ring is rotated so that the structure cannot ensure the symmetric characteristics, it has a significant impact on the frequency band where the resonant frequency point is located, especially the absorption rate of the first frequency point is extremely obvious.
[0041] Example 6
[0042] The same method is used to analyze the influence of the thickness of the air layer of the metamaterial absorber on the simulation effect. The simulation calculation results of the model absorption rate under different air layer thicknesses are as follows: Figure 8 As shown. In the air layer thickness In the process of increasing from 0 to 4mm: the resonant frequency of the first absorption frequency point moves toward the low frequency direction as the thickness of the air layer increases, and the absorption rate shows a trend of first decreasing and then increasing. The absorption rate reaches its maximum value (100%) when the thickness of the air layer increases, and it can still achieve an absorption effect of more than 80% at other air layer thicknesses. The resonant frequency of the second absorption frequency point moves toward the low frequency direction as the thickness of the air layer increases, and the overall absorption rate shows an upward trend. , the absorption rate reaches more than 99%. The resonance frequency of the third absorption frequency point moves toward the low frequency direction with the increase of the thickness of the air layer, and its absorption rate shows a slight downward trend. While reaching its lowest value at , it still maintains an absorption efficiency of approximately 98%. The above analysis shows that as the thickness of the air layer increases, the resonant frequencies of the three absorption frequencies all shift toward lower frequencies. The absorption rate of the first frequency shows an initial increase followed by a decrease, the absorption rate of the second frequency shows an increasing trend, and the absorption rate of the third frequency shows a slight decrease. These results demonstrate that the operating frequency can be adjusted by varying the air layer thickness, with minimal change in absorption efficiency. Therefore, the designed metamaterial absorber exhibits tunable properties.
[0043] Example 7
[0044] Through the analysis of Example 2, it can be seen that the wave absorption effect of the three-frequency point of the metamaterial is closely related to the existence of the metal pattern layer. In order to explore the influence of the various structures of the metal layer on the wave absorption effect of the metamaterial, two groups of structures, one with a slit ring removed and one with a symmetric semicircle, were set up for comparison with the original structure. The absorption rate curve obtained by simulation is shown in the figure below. Figure 9 As shown. When the slit ring is removed, the first absorption frequency disappears while the second and third absorption frequencies move toward the low-frequency direction as a whole, and the absorption rate of the second absorption frequency is significantly reduced. This shows that the existence of the slit ring is very critical to the first and second absorption frequencies. When the symmetrical semicircle is removed, the third absorption frequency disappears while the absorption rate of the second absorption frequency is significantly reduced and the absorption frequency moves toward the high-frequency direction, which shows that the existence of the symmetrical semicircle is very important to the second and third absorption frequencies. The above simulation experimental results show that the existence of the slit ring directly determines the existence of the first absorption frequency, and the symmetrical semicircle determines the existence of the third absorption frequency. At the same time, according to the analysis of Example 2, when the metal layer is removed and the water layer is retained, there is only one absorption frequency (i.e., the second frequency) and the absorption rate of the absorption frequency is low, and the existence of the slit ring and the symmetrical semicircle has a great influence on the absorption rate of the second absorption frequency. Therefore, the influence of the slit ring and the symmetrical semicircle structure in the metal pattern layer on the wave absorbing effect of the metamaterial is very important.
[0045] In summary, the present invention proposes a water-metal hybrid metamaterial absorber. This device achieves near-perfect absorption at three low-frequency points between 0 and 1 GHz, exhibits polarization sensitivity, and absorbs waves at wide angles of incidence. Furthermore, the operating frequency range and absorption efficiency can be dynamically adjusted by varying the thickness of the air layer.
[0046] The above embodiments describe preferred embodiments of the present invention, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent of the present invention shall be based on the appended claims.
Claims
1. A water-metal hybrid metamaterial absorber, characterized by: The absorber comprises a plurality of periodically arranged structural units, each of which is in the shape of a rectangular parallelepiped and comprises, from bottom to top, a metal base plate layer, an air layer, an organic glass layer, a dielectric plate layer, a metal pattern layer, a water layer, and an organic glass layer. The metal pattern layer is located on the upper surface of the dielectric plate layer and is an axisymmetric or centrosymmetric pattern. The metal pattern layer comprises two semicircles, a slotted circular ring between the two semicircles, and a cross structure formed by two mutually perpendicular rectangles of equal length and width within the slotted circular ring. The center of the semicircle is located at the center of the wide side of the dielectric plate layer, the center of the slotted circular ring coincides with the center of the cross, and the slotted circular ring has two slots perpendicular to the long side of the dielectric plate layer. The radius of the semicircle is 13.5-14 mm. The inner and outer diameters of the slotted circular ring are 11.5-12 mm and 14.5-15 mm, respectively, and the slot width is 2.8-3 mm. The length and width of the rectangles forming the cross structure are 13.5-14 mm and 2.8-3 mm, respectively.
2. The absorber according to claim 1, wherein: The length of the structural unit is 59~60mm, the width is 29~30mm, and the thickness is 12.40~12.50mm.
3. The absorber according to claim 2, wherein: The metal bottom plate layer is made of copper material with a thickness of 0.025mm~0.035mm.
4. The absorber according to claim 1, wherein: The thickness of the air layer is 1~1.2mm.
5. The absorber according to claim 1, wherein: The dielectric board layer is FR4 with a dielectric constant of 4.2~4.3 and a thickness of 1~1.2mm.
6. The absorber according to claim 1, wherein: The thickness of the water layer is 8.0mm~8.6mm.
7. The absorber according to claim 1, wherein: The metal pattern layer is made of copper material and has a thickness of 0.025mm~0.035mm.
8. Application of the water-metal hybrid metamaterial absorber according to any one of claims 1 to 7 in the fields of electromagnetic absorption and electromagnetic shielding.