Liquid-based reconfigurable wave absorber with wideband wave-transparent window

Abstract

The application discloses a liquid-based reconfigurable wave absorber with a broadband wave-transparent window and belongs to the technical field of electromagnetic metamaterials. The liquid-based reconfigurable wave absorber comprises an upper container, a water structure, an intermediate medium layer and a lower wave-transparent structure. The upper container and the intermediate medium layer form a closed structure, and water is filled in the closed space. The application utilizes the dispersion characteristics and high dielectric loss of water, firstly constructs a broadband wave absorber without a metal bottom plate, then combines the water-based broadband wave absorber with a second-order passband frequency selective surface, utilizes different water injection modes (injection and discharge), designs a reconfigurable structure with wave absorption and wave transmission integrated, adjusts impedance matching, and realizes the performance of a small transmission window insertion loss.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic metamaterials technology, specifically a liquid-based reconfigurable absorber with a broadband wave transmission window. Background Technology

[0002] Metamaterials are composite materials composed of subwavelength unit structures that possess electromagnetic properties not found in natural materials, such as negative refractive index, inverse Doppler, and inverse Cherenkov. Traditional absorbing structures have narrow absorption bandwidths, while traditional broadband absorbing structures involve complex metallic surface structures or combinations of multiple resonant units, which have significant drawbacks such as complex processing, high cost, large thickness, and susceptibility to oxidation and corrosion. With the rapid development of technology and the continuous upgrading of electronic devices, the demand for stealth technology is increasing. Single-function absorbing structures can no longer meet the needs of current radar and communication systems, while frequency selective surfaces (FSS) with both absorption and transmission functions can perfectly solve this problem. Currently, most FSSs on the market cannot change their electromagnetic properties once fabricated, meaning they cannot cope with complex and variable electromagnetic environments. Summary of the Invention

[0003] This invention proposes a liquid-based reconfigurable absorber with a broadband wave transmission window, which can effectively solve the problems of complex processing and limited functionality of existing absorber structures.

[0004] The technical solution to achieve the purpose of this invention is as follows: a liquid-based reconfigurable absorber with a broadband wave-transmitting window, comprising multiple periodically distributed units, each unit comprising an upper container, an intermediate dielectric layer and a lower wave-transmitting structure from top to bottom, wherein a structured water layer is provided in the upper container, the structured water layers between units are interconnected, and the upper container and the structured water layer constitute a resonator to achieve broadband absorption.

[0005] Preferably, the lower transparent structure includes two dielectric substrates B1 and B2 and three different metal layers A1, A2 and A3. The two dielectric substrates and the three metal layers are designed to be spaced apart. The top and bottom metal layers A1 and A3 are both capacitor patches, and the size of the top capacitor patch is different from that of the bottom capacitor patch. The middle metal layer A2 is a cross-shaped inductor patch.

[0006] Preferably, the capacitor patch is circular, Jerusalem cross-shaped, square ring-shaped, or a combination of the above shapes.

[0007] Preferably, both dielectric substrates B1 and B2 are made of F4B dielectric material with a relative permittivity of 3.3 and a loss tangent of 0.0007, and both have a thickness of 0.5 mm.

[0008] Preferably, the cross-shaped inductor patch has a length of 4mm and a width of 1.7mm.

[0009] Preferably, the structured water layer includes an upper cylindrical structured water layer and a lower irregular water structure. The lower irregular water structure is a cube with the centers of four adjacent units as the center of a circle, and the four corners of the lower irregular water structure are cut off by circles of a set radius.

[0010] Preferably, the upper cylindrical water structure has a radius of 1.5 mm and a height of 1.8 mm; the lower irregular water structure has a height h3 of 0.6 mm and a radius r2 of 0.8 mm for the cut-off portion.

[0011] Preferably, the structured water layer is injected with liquids such as distilled water, sodium chloride solution, and ethylene glycol aqueous solution.

[0012] Preferably, the upper container and the intermediate medium layer are made of materials such as polymethyl methacrylate, polydimethylsiloxane, and thermoplastic polyurethane.

[0013] Compared with the prior art, the significant advantages of this invention are:

[0014] Compared with traditional complex metal surface structures or combinations of multiple resonant structures, the structure of this invention is relatively simple and easy to manufacture; this invention utilizes the dispersive characteristics, high loss characteristics and fluidity of water to realize a broadband, reconfigurable liquid-based absorber.

[0015] The broadband liquid-based absorber designed in this invention does not require a metal base plate. It is combined with a frequency selective surface with wave transmission function, and by adjusting the structural parameters to ensure impedance matching, the design of a broadband absorption / transmission integrated reconfigurable structure is realized.

[0016] The geometric structure of this invention has a high degree of symmetry, which can obtain relatively stable dual-polarization characteristics;

[0017] For electromagnetic waves with an incident angle in the range of 0° to 45°, this invention can maintain an absorption rate of over 85% in the absorption frequency band when filled with water; and in the absence of water, it still maintains good transmission performance in the passband frequency band, with a minimum insertion loss of 0.15dB. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of an array of liquid-based reconfigurable absorbers with a broadband wave transmission window;

[0019] Figure 2 This is a side view of a unit of a liquid-based reconfigurable absorber with a broadband wave transmission window.

[0020] Figure 3 This is a schematic diagram of the water structure (2) of a reconfigurable absorber;

[0021] Figure 4 This is a schematic diagram of the wave-transmitting structure (4) of a reconfigurable absorber;

[0022] Figure 5 This is a schematic diagram of water injection / drainage of a liquid-based reconfigurable absorber with a broadband wave transmission window;

[0023] Figure 6 It is a waveform diagram showing the absorption / transmission curves of a liquid-based reconfigurable absorber with a broadband transmission window in both water-containing and waterless operating states.

[0024] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures. Detailed Implementation

[0025] To further clarify the purpose, technical solution, and advantages of the present invention, the present invention will be described in detail below with reference to the accompanying drawings.

[0026] A liquid-based reconfigurable absorber with a broadband wave-transmitting window includes multiple periodically distributed units. Each unit comprises, from top to bottom, an upper container 1, an intermediate dielectric layer 3, and a lower wave-transmitting structure 4. A structured water layer 2 is disposed within the upper container 1, and the structured water layers 2 of the units are interconnected. The upper container 1 and the structured water layers 2 constitute a resonator, achieving broadband absorption. This invention arranges each unit periodically, ensuring that the structured water layers 2 of each unit are interconnected, thus better utilizing the fluidity of water. By utilizing the upper container 1 and the structured water layers 2 to form a high-loss resonant cavity, broadband absorption can be achieved in a liquid-based absorber without a metal base plate.

[0027] In a further embodiment, the lower wave-transmitting structure 4 includes two dielectric substrates B1 and B2 and three different metal layers A1, A2, and A3. The two dielectric substrates and the three metal layers are spaced apart. The top and bottom metal layers A1 and A3 are both capacitor patches, and the size of the top metal layer is different from that of the bottom metal layer. The middle metal layer A2 is a cross-shaped inductor patch, achieving low-loss wave transmission in a specific waveband. When the structural water layer 2 is filled with water and combined with the wave-transmitting structure 4, the wave-transmitting structure 4 can act as a metal backplate, allowing the incident electromagnetic waves to be better attenuated by the structural water layer 2; thus realizing a reconfigurable structure design that integrates wave absorption and wave transmission. When the water in the structural water layer 2 is drained, combined with the wave-transmitting structure 4, a low-loss transmission window can be generated in a specific frequency band within the wave absorption range.

[0028] In a further embodiment, the structural water layer 2 is injected / discharged with water through microfluidic channels.

[0029] In a further embodiment, the capacitor patch is circular, Jerusalem cross-shaped, square ring-shaped, or a combination of the above shapes.

[0030] In a further embodiment, the structural water layer 2 includes an upper cylindrical structural water layer 2-1 and a lower irregular water structure 2-2. The lower irregular water structure 2-2 is a cube with the centers of four adjacent units as the center of a circle, and the four corners of the lower irregular water structure 2-2 are cut off by circles of a set radius.

[0031] like Figure 5 As shown, if water is injected into the structural water layer 2 through the microfluidic channel inlet (Injector_1) on one side of the periodic array, the structure can be considered a broadband absorber when the structural water layer 2 is full of water. Conversely, if water is drained from the structural water layer 2 through the microfluidic channel inlet (Injector_2) on the other side of the periodic array, a broadband transmission window is generated in the absorption frequency band when the structural water layer 2 is empty. This invention combines different water injection states (injection / drainage) to put the structure in different working states, thus achieving reconfigurable performance of integrated absorption / transmission.

[0032] Example

[0033] refer to Figure 1-5 The descriptions are respectively a schematic diagram of an array of a liquid-based reconfigurable absorber with a broadband wave-transmitting window proposed in this invention, a side view of the unit structure, a schematic diagram of the structured water, a schematic diagram of the lower wave-transmitting structure, and a schematic diagram of the array's water injection / drainage.

[0034] like Figure 1 As shown, a liquid-based reconfigurable absorber with a broadband wave transmission window includes multiple periodically arranged units.

[0035] like Figure 2 As shown in the side view of the unit structure designed in this invention, from top to bottom, it includes an upper container 1, an intermediate dielectric layer 3, and a lower wave-transparent structure 4. A closed space is formed between the upper container 1 and the intermediate dielectric layer 3. A structural water layer 2 is provided in the closed space. The structural water layers 2 between units are interconnected. The upper container 1 and the structural water layer 2 constitute a resonator to achieve broadband absorption.

[0036] The side length of a single unit structure is 4 mm, and the overall thickness is 6.1 mm. Both the upper container 1 and the intermediate dielectric layer 3 are made of polymethyl methacrylate, with a relative permittivity of 3 and a loss tangent of 0.001. The thicknesses of the upper container 1 and the intermediate dielectric layer 3 are 4.4 mm and 0.7 mm, respectively.

[0037] Specific parameters of structural water layer 2 are as follows: Figure 3As shown, the upper cylindrical water structure 2-1 has a radius of 1.5 mm and a height of 1.8 mm; the lower irregular water structure 2-2 is a cube with circles of a set radius centered on the centers of four adjacent units, cutting off the four corners of the lower irregular water structure 2-2. The radius r2 of the cut-off portion of the lower irregular water structure 2-2 is 0.8 mm, and the height h3 is 0.6 mm.

[0038] The entire structural water layer 2 is enclosed by the upper container 1 and the intermediate medium layer 3. When the structural water layer 2 is filled with water, the liquid-based absorber can achieve an absorption rate of over 90% in the 10–28.72 GHz range. When the structural water layer 2 is empty, the structure generates a transmission window within the 10–28.72 GHz absorption band, with a frequency range of 10.78–12.64 GHz and a minimum insertion loss of 0.15 dB. This allows for a reconfigurable structure integrating absorption and transmission by combining different water injection / discharge methods. The liquid used in this invention is distilled water at room temperature (25°C) and one standard atmosphere.

[0039] The specific parameters of the lower wave-transparent structure 4 are as follows: Figure 4 As shown, both dielectric substrates B1 and B2 are made of F4B dielectric material with a relative permittivity of 3.3 and a loss tangent of 0.0007, and a thickness of 0.5 mm. The top and bottom of the structure are composed of metal patches A1 and A3 with side lengths of 3.85 mm and 3.89 mm, respectively, and the middle metal layer is composed of a cross-shaped inductive patch A2 with a length of 4 mm and a width of 1.7 mm.

[0040] like Figure 5 As shown, the present invention can perform water injection and drainage through the lower irregular water layer 2-2 of the structural water layer 2 on both sides.

[0041] The reconfigurable method and materials for integrated wave absorption / transmission in this invention are not limited to these. Regarding the reconfigurable method, in addition to changing the liquid injection / discharge state, reconfigurable characteristics can also be achieved by changing the liquid concentration, type, and volume. In terms of materials, besides polymethyl methacrylate, the upper container 1 and the intermediate dielectric layer 3 can also be made of materials such as polydimethylsiloxane and thermoplastic polyurethane, as long as impedance matching is met; besides distilled water, the liquid in the structured water 2 can also be other liquids such as sodium chloride solution and ethylene glycol aqueous solution, and their concentration can be selected as needed; besides being designed in a square or cross shape, the capacitor patch of the lower wave-transmitting structure can also be designed in a circular, Jerusalem cross shape, square ring shape, or a combination of multiple shapes. Different wave-transmitting structures can also be combined with the broadband wave-absorbing structure formed by the upper container 1 and the structured water layer 2, and the design and adjustment can be made according to the actual engineering requirements.

[0042] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A liquid-based reconfigurable absorber with broadband transparent window, characterized in that, The application relates to a broadband wave-absorbing structure, which comprises a plurality of units arranged in a periodic distribution, each unit comprising, from top to bottom, an upper container (1), an intermediate medium layer (3) and a lower wave-transparent structure (4), a closed space being formed between the upper container (1) and the intermediate medium layer (3), a structural water layer (2) being arranged in the closed space, the structural water layers (2) between the units being interconnected, the upper container (1) and the structural water layer (2) forming a resonator, and wideband absorption being realized. The lower wave-transparent structure (4) comprises two medium substrates B1 and B2 and three different metal layers A1, A2 and A3, the two medium substrates and the three metal layers being designed in a spaced manner, the topmost and bottommost metal layers A1 and A3 being capacitive patches, the size of the topmost capacitive patch being different from that of the bottommost capacitive patch, and the middle metal layer A2 being a cross-shaped inductive patch. The structural water layer (2) comprises an upper cylindrical structural water (2-1) and a lower irregular water structure (2-2), the lower irregular water structure (2-2) being a cube and having four corners cut away by circles with centers at the centers of four adjacent units and with a set radius. When the structural water layer (2) is filled with water and combined with the wave-transparent structure (4), the wave-transparent structure (4) plays a role of a metal back plate; when the water in the structural water layer (2) is drained, in combination with the wave-transparent structure (4), a low-loss transmission window is generated in a specific frequency band in a wave-absorbing range.

2. The liquid-based reconfigurable absorber with broadband wave-transparent window of claim 1, wherein, The capacitive patch is designed in a rectangular, circular, Jerusalem cross, square ring or combination of the above shapes.

3. The liquid-based reconfigurable absorber with broadband transmission window of claim 1, wherein, Both the two medium substrates B1 and B2 adopt F4B medium material with a relative dielectric constant of 3.3 and a loss tangent of 0.0007, and the thicknesses of the two medium substrates are both 0.5 mm.

4. The liquid-based reconfigurable absorber with broadband transmission window of claim 1, wherein, The cross-shaped inductive patch has a length of 4 mm and a width of 1.7 mm.

5. The liquid-based reconfigurable absorber with broadband transmission window of claim 1, wherein, The upper cylindrical water structure (2-1) has a radius of 1.5 mm and a height of 1.8 mm; the lower irregular water structure (2-2) has a height of 0.6 mm and a radius of 0.8 mm. h3 The upper cylindrical water structure (2-1) has a radius of 1.5 mm and a height of 1.8 mm; the lower irregular water structure (2-2) has a height of 0.6 mm and a radius of 0.8 mm. r2 The upper cylindrical water structure (2-1) has a radius of 1 6. The liquid-based reconfigurable absorber with broadband transmission window of claim 1, wherein, The structural water layer (2) is filled with distilled water at room temperature of 25 DEG C and under a standard atmospheric pressure.

7. The liquid-based reconfigurable absorber with broadband transmission window of claim 1, wherein, The structural water layer (2) is filled with a sodium chloride solution or a glycol aqueous solution, and the concentration is selected as required.

8. The liquid-based reconfigurable absorber with broadband transmission window of claim 1, wherein, The upper container (1) and the intermediate medium layer (3) adopt polymethyl methacrylate or polydimethylsiloxane.

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