A curved conformal skin that is both absorbing and transparent

Abstract

The application discloses a curved conformal absorbing and transmitting integrated skin which is composed of a plurality of periodically arranged super surface units, and includes an impedance layer and a transmission reflection layer, the transmission reflection layer is arranged below the impedance layer, and the transmission reflection layer and the impedance layer are separated by a third supporting layer, wherein the impedance layer includes a first absorbing layer, a first supporting layer, a second absorbing layer, a second supporting layer and a third supporting layer; the wave-transmitting reflection layer includes a first metal ring layer, a first dielectric substrate, a first patch layer, a fourth supporting layer, a second metal ring layer, a second dielectric substrate, a third metal ring layer, a fifth supporting layer, a second patch layer, a third dielectric substrate and a fourth metal ring layer which are sequentially arranged. The application can realize low-frequency communication wave-transmitting state and high-frequency protection absorbing shielding state of the super surface at different frequency bands without manual intervention and external power supply, and can be conformal with a carrier with a certain curvature.

Description

Technical Field

[0001] This invention relates to electromagnetic stealth technology, specifically to a curved, conformal, breathable, integrated skin. Background Technology

[0002] Electromagnetic stealth materials are of great significance in modern electronic systems, effectively protecting sensitive electronic devices from external interference signals and ensuring the normal operation and security of the system. Traditional electromagnetic stealth materials, such as ferrites, polycrystalline fibers, and graphite fibers, while possessing significant functionality, are bulky, heavy, and expensive, limiting their widespread use in practical applications. To overcome these shortcomings, in recent years, researchers have begun to use novel devices based on artificial electromagnetic structures, such as absorbers and diffusers, as new electromagnetic stealth materials. Currently, traditional artificial electromagnetic stealth materials, although performing well in specific frequency ranges, suffer from limitations such as limited absorption angles and single functionality. For example, many existing absorbing materials often experience a significant reduction in absorption effectiveness at large incident angles and cannot simultaneously meet wave transmission requirements, posing a challenge to the stealth protection of electronic systems. Therefore, the development of a conformal absorber-transmitter integrated metasurface structure with large-angle absorption capabilities is urgently needed, and this technology has broad application prospects. Summary of the Invention

[0003] The purpose of this invention is to provide a conformal, absorbent integrated skin that can achieve low-frequency wave transmission and high-frequency large-angle incident radiation protection at different frequency bands without manual intervention or external power supply.

[0004] The technical solution to achieve the purpose of this invention is as follows: a curved conformal breathable integrated skin, composed of multiple periodically arranged metasurface units, including an impedance layer and a transmission / reflection layer, wherein the transmission / reflection layer is disposed below the impedance layer, and a third support layer is separated from the transmission / reflection layer and the impedance layer, wherein:

[0005] The impedance layer comprises a first absorption layer, a first support layer, a second absorption layer, a second support layer, and a third support layer, wherein:

[0006] The first and second absorption layers are made of resistive thin film material. The sheet resistance of the resistive film in the first absorption layer is smaller than that in the second absorption layer. The first support layer, the second support layer and the third support layer are made of PMI foam material with low dielectric constant.

[0007] The first absorbent layer, the first support layer, the second absorbent layer, and the second support layer form a mushroom-shaped three-dimensional structure. The first absorbent layer covers the top of the first support layer, the second support layer is located at the bottom of the first support layer, and the second absorbent layer covers the periphery of the second support layer. The mushroom-shaped three-dimensional structure is bonded to or embedded in the third support layer.

[0008] The wave-transparent reflective layer comprises, in sequence, a first metal ring layer, a first dielectric substrate, a first patch layer, a fourth support layer, a second metal ring layer, a second dielectric substrate, a third metal ring layer, a fifth support layer, a second patch layer, a third dielectric substrate, and a fourth metal ring layer, wherein:

[0009] The first, second, third, and fourth metal ring layers all use rectangular annular metal patches. The outer side length of the rectangular annular metal patches in the first and third metal ring layers is smaller than the side length of the transmission and reflection layer unit; the outer side length of the rectangular annular metal patches in the second and fourth metal ring layers is equal to the side length of the transmission and reflection layer unit.

[0010] The fourth and fifth support layers are made of PMI foam material with high dielectric constant;

[0011] The first and second patch layers each have four rectangular patches, each with a perforated structure at one corner. In the first and second patch layers, the four rectangular patches are arranged in a 2*2 matrix, forming a cross gap in the middle. The perforated structure of each layer is located at the four corners of the transmissive and reflective layer unit patch layer.

[0012] Furthermore, the transmission and reflection layer is disposed 1 mm below the impedance layer.

[0013] Furthermore, the sheet resistance of the resistive film in the first absorption layer is set to 150 Ω / m. 2 The sheet resistance of the resistive film in the second absorption layer is set to 500 Ω / m. 2 .

[0014] Furthermore, the dielectric constant ε of the first support layer, the second support layer, and the third support layer r =1.07, loss tangent tanδ =0.001.

[0015] Furthermore, the dielectric constant ε of the fourth and fifth support layers... r =3.25, loss tangent tanδ =0.005.

[0016] Furthermore, the first dielectric substrate, the second dielectric substrate, and the third dielectric substrate are F4B dielectric substrates.

[0017] Furthermore, the first and second support layers are formed by cutting grooves in a single piece of PMI foam material, and the third support layer is grooved according to the size of the second support layer, so that the second support layer is embedded into the third support layer.

[0018] Furthermore, the first metal ring layer adopts a first rectangular annular metal patch, which is placed at the center of the transmission and reflection layer unit, and the outer side length of the first rectangular annular metal patch is smaller than the side length of the transmission and reflection layer unit.

[0019] The second metal ring layer adopts a second rectangular annular metal patch, which is placed at the center of the transmission and reflection layer unit. The outer side length of the second rectangular annular metal patch is equal to the side length of the transmission and reflection layer unit and coincides with the boundary of the transmission and reflection unit.

[0020] The third metal ring layer adopts a third rectangular ring metal patch, which is placed at the center of the transmission and reflection layer unit. The outer side length of the third rectangular ring metal patch is equal to the side length of the transmission and reflection layer unit and coincides with the boundary of the transmission and reflection unit.

[0021] The fourth metal ring layer adopts a fourth rectangular annular metal patch, which is placed at the center of the transmission and reflection layer unit. The outer side length of the fourth rectangular annular metal patch is equal to the side length of the first rectangular annular metal patch.

[0022] Furthermore, the second patch layer has the same size parameters as the first patch layer.

[0023] Furthermore, when high-frequency electromagnetic waves are incident, the electromagnetic waves incident on the conformal, penetrating integrated skin cannot generate sufficiently strong resonance, and the overall structure exhibits a high-resistivity state, being in a state of electromagnetic wave transmission, while also having low insertion loss. When high-frequency electromagnetic waves are incident, the electromagnetic waves incident on the conformal, penetrating integrated skin resonate with the transmission and reflection layer. At this time, the transmission and reflection layer exhibits a reflection state, and the absorption layer absorbs both the incident electromagnetic waves and the electromagnetic waves reflected by the transmission and reflection layer. The overall structure exhibits an absorption state, exhibiting a high cutoff effect, while maintaining absorption efficiency when electromagnetic waves are incident at large angles.

[0024] Compared with existing technologies, the significant advantages of this invention are: 1) Composed of an impedance layer, a dielectric layer, a foam layer, and a metal patch, it simultaneously absorbs and transmits spatial electromagnetic waves. That is, when low-frequency electromagnetic waves are incident, they can pass through with low insertion loss, without affecting the transmit / receive performance of the RF front-end antenna; when high-frequency electromagnetic waves are incident, the metasurface is in an absorbing state to achieve electromagnetic shielding. It can achieve low-frequency communication transmission and high-frequency protection absorption shielding states at different frequency bands without manual intervention or external feeding. 2) Using a three-dimensional absorbing structure model, it has excellent angular stability and polarization insensitivity, maintaining good out-of-band absorption performance even at large angles or grazing incidence. 3) The dielectric substrate is relatively thin, allowing it to conform to a carrier with a certain curvature. Attached Figure Description

[0025] Figure 1 A schematic diagram of a conformal, breathable, integrated skin unit structure;

[0026] Figure 2 Diagram of a conformal, breathable, integrated skin array;

[0027] Figure 3 This is a schematic diagram of the impedance layer structure;

[0028] Figure 4 This is a schematic diagram of the transmission and reflection layer;

[0029] Figure 5 Schematic diagram of the incident angle of electromagnetic waves

[0030] Figure 6 S for different incident angles of the conformal integrated skin for absorbing light from curved surfaces 21 parameter;

[0031] Figure 7 S for different incident angles of the conformal integrated skin for absorbing light from curved surfaces 11 parameter;

[0032] Figure 8 The insertion loss of the conformal, penetrating, integral skin at 0° and 60° incidence;

[0033] Figure 9 The out-of-band absorption rate of the conformal, transmissive integrated skin under large-angle incidence.

[0034] Symbol explanation:

[0035] 1-Resistive film, 2-Metallic copper, 3-Low dielectric PMI foam, 4-High dielectric PMI foam, 5-F4B dielectric substrate Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0037] like Figure 1 , 2 As shown, the conformal transmissive integrated skin consists of a resistive film 1, a metal patch 2, a low dielectric constant PMI material 3, a high dielectric constant PMI material 4, and an F4B dielectric substrate 5. It employs a periodic arrangement of multiple metasurface units, which are centrally symmetrical and divided into an upper impedance layer and a lower transmission / reflection layer, separated from the impedance layer by a third support layer.

[0038] (1) Impedance layer

[0039] like Figure 1 , 2 As shown in Figure 3, the impedance layer includes a first absorption layer, a first support layer, a second absorption layer, a second support layer, and a third support layer.

[0040] The first and second absorption layers use a resistive film with a certain sheet resistance as the absorbing material. The sheet resistance of the resistive film in the first absorption layer is smaller than that in the second absorption layer. The first support layer, the second support layer and the third support layer use PMI foam material with low dielectric constant.

[0041] The first absorbent layer, the first support layer, the second absorbent layer, and the second support layer form a mushroom-shaped three-dimensional structure. The first absorbent layer covers the top of the first support layer, the second support layer is located at the bottom of the first support layer, and the second absorbent layer covers the perimeter of the second support layer. The mushroom-shaped three-dimensional structure is bonded to or embedded in the third support layer.

[0042] Furthermore, the impedance layer consists of a resistive thin film and a low dielectric constant PMI material (ε... r Composed of dielectric constants ε (e.g., ε = 1.07, tanδ = 0.001), the dielectric constant ε measures a material's polarization capability under an electric field, reflecting its ability to store electrical energy. The dielectric constant is defined as the ratio of a material's capacitance to its vacuum capacitance, and is commonly used to describe the degree of polarization of a dielectric in an electric field. Materials with high dielectric constants, such as water, ceramics, or special dielectrics, are suitable for applications requiring high charge storage capacity, such as capacitors and microwave devices. Conversely, materials with low dielectric constants, such as air or polytetrafluoroethylene (PTFE), are often used for insulation and isolation applications. The loss tangent tanδ, also known as the dielectric loss tangent, describes the energy loss of a material under an electric field. It represents the energy lost due to internal friction in an alternating current electric field. The loss tangent value can be obtained by measuring the dielectric loss angle, which is measured simultaneously with the dielectric constant and is independent of the size and shape of the sample, representing an intrinsic property of the dielectric. Materials with low loss tangents are suitable for high-frequency devices, reducing signal attenuation and heat loss.

[0043] Furthermore, the sheet resistance of the resistive film in the first absorption layer is set to 150 Ω / m. 2 The sheet resistance of the resistive film in the second absorption layer is set to 500 Ω / m. 2 .

[0044] Furthermore, the support structure of the impedance layer is formed by grooving PMI foam, offering high design flexibility and low cost. The first and second support layers are formed by grooving a single piece of PMI foam material, while the third support layer is grooved according to the dimensions of the second support layer, allowing the second support layer to be embedded within the third support layer. When electromagnetic waves with a small incident angle are incident, the first absorption layer plays a major absorption role; when electromagnetic waves with a large incident angle or grazing incident angle are incident, the second absorption layer plays a major absorption role.

[0045] (2) Wave-transparent reflective layer

[0046] like Figure 1 , 2 As shown in Figure 4, the wave-transparent reflective layer includes a first metal ring layer, a first dielectric substrate, a first patch layer, a fourth support layer, a second metal ring layer, a second dielectric substrate, a third metal ring layer, a fifth support layer, a second patch layer, a third dielectric substrate, and a fourth metal ring layer arranged sequentially.

[0047] The first, second, third, and fourth metal ring layers all use rectangular annular metal patches. The outer side length of the rectangular annular metal patches in the first and third metal ring layers is smaller than the side length of the transmission and reflection layer unit; the outer side length of the rectangular annular metal patches in the second and fourth metal ring layers is equal to the side length of the transmission and reflection layer unit.

[0048] The fourth and fifth support layers are made of PMI foam material with high dielectric constant;

[0049] The first and second patch layers each have four rectangular patches, each with a perforated structure at one corner. In the first and second patch layers, the four rectangular patches are arranged in a 2*2 matrix, forming a cross gap in the middle. The perforated structure of each layer is located at the four corners of the transmissive and reflective layer unit patch layer.

[0050] Furthermore, the first and fourth metal ring layers have the same structure, and the second and third metal ring layers have the same structure. The first metal ring layer is composed of a first rectangular annular metal patch, which is placed at the center of the transmission / reflection layer unit, and the outer side length of the first rectangular annular metal patch is less than the side length of the transmission / reflection layer unit. The second metal ring layer is composed of a second rectangular annular metal patch, which is placed at the center of the transmission / reflection layer unit, and the outer side length of the second rectangular annular metal patch is equal to the side length of the transmission / reflection layer unit, coinciding with the unit boundary. The third metal ring layer is composed of a third rectangular annular metal patch, which is placed at the center of the transmission / reflection layer unit, and the outer side length of the third rectangular annular metal patch is equal to the side length of the transmission / reflection layer unit, coinciding with the unit boundary. The fourth metal ring layer is composed of a fourth rectangular annular metal patch, which is placed at the center of the transmission / reflection layer unit, and the outer side length of the fourth rectangular annular metal patch is equal to the side length of the transmission / reflection layer unit.

[0051] Furthermore, the first patch layer and the second patch layer are centrally symmetrical structures. The first patch layer includes a first patch, a second patch, a third patch, a fourth patch, a first porous structure, a second porous structure, a third porous structure, a fourth porous structure, a first slot structure, and a second slot structure. The first slot structure and the second slot structure are located at the axis of symmetry of the first patch, the second patch, the third patch, and the fourth patch and are perpendicular to each other. The first porous structure is located at the upper left corner of the unit boundary, the second porous structure is located at the lower left corner of the unit boundary, the third porous structure is located at the upper right corner of the unit boundary, and the fourth porous structure is located at the lower right corner of the unit boundary. The second patch layer has the same structure and dimensional parameters as the first patch layer.

[0052] Furthermore, the support layer is made of PMI foam material with a high dielectric constant (ε). r =3.25, tanδ=0.005). The transmission and reflection layer can be equivalent to a capacitor-inductor-capacitor parallel circuit, where the first metal ring layer, the third metal ring layer, the first patch layer, and the second patch layer are equivalent to capacitors when arranged periodically, and the second metal ring layer is equivalent to an inductor, which can achieve the filtering function of "low pass and high reflection". In particular, due to the multi-layer structure, the structure has good high cutoff performance outside the band, effectively preventing high-frequency electromagnetic waves outside the band from passing through the structure. At this time, the transmission and reflection layer is in a reflection state. At low frequencies, the incident electromagnetic waves are difficult to resonate in the structure, and the transmission and reflection layer is in a wave-transmitting state, which has a low insertion loss.

[0053] Furthermore, the first dielectric substrate, the second dielectric substrate, and the third dielectric substrate are F4B dielectric substrates.

[0054] When low-frequency electromagnetic waves are incident, the electromagnetic waves incident on the metasurface cannot generate sufficiently strong resonance, and the overall structure exhibits a high-resistivity state, being in a state of electromagnetic wave transmission, while also possessing low insertion loss. When high-frequency electromagnetic waves are incident, the electromagnetic waves incident on the metasurface resonate with the transmission and reflection layers. At this time, the transmission and reflection layers exhibit a reflection state, and the absorption layer absorbs both the incident electromagnetic waves and the electromagnetic waves reflected by the transmission and reflection surfaces. The overall structure exhibits an absorption state, while also possessing a high cutoff effect, and maintaining excellent absorption performance even when electromagnetic waves are incident at large angles.

[0055] In summary, the integrated absorber metasurface exhibits polarization insensitivity. It demonstrates excellent angular stability, maintaining good out-of-band absorption performance even at large angles and grazing incidence. Furthermore, due to its thin dielectric substrate, it can conformally fit with a carrier of a certain curvature.

[0056] Example

[0057] To verify the effectiveness of the present invention, the following experimental design was conducted.

[0058] In this embodiment, a conformal, osmotically arranged 3*3 metasurface units are used to form a curved, conformal, integrated osmotic skin. The conformal, osmotically arranged skin exhibits good angular stability, with its electromagnetic wave incident angle as follows: Figure 5 As shown, the impedance layer adopts a mushroom-shaped three-dimensional structure, which can effectively meet the absorption requirements of electromagnetic waves incident at large angles. When the incident out-of-band electromagnetic waves are incident normally or at a small angle, the first absorption layer plays a major role; when the incident angle is large, the second absorption layer plays a major role. The transmission and reflection layer is designed to transmit waves within the band and reflect them outside the band. Therefore, when high-frequency out-of-band electromagnetic waves are incident, they will be strongly reflected by the transmission and reflection layer, further enhancing the absorption capability of the impedance layer.

[0059] Conformal integrated skin for breathability under different incident angles 21 Parameters such as Figure 6 As shown, the incident angle is as follows Figure 5 As shown. Figure 6 This indicates that the metasurface exhibits excellent high transmittance within the band (2.8-3.2 GHz) and high cutoff outside the band (8-12 GHz), and in particular, it maintains good cutoff performance even at 85° grazing incidence.

[0060] Conformal integrated skin for breathability under different incident angles 11 Parameters such as Figure 7 As shown, the incident angle is as follows Figure 5 As shown. Figure 7 This indicates that the metasurface exhibits excellent high transmittance within the band (2.8-3.2 GHz) and high cutoff outside the band (8-12 GHz). Furthermore, the out-of-band S...11 The parameters are small at large angles of incidence, which indicates that the impedance layer absorbs a large amount of electromagnetic waves reflected by the transmission and reflection layer. Combined with the high out-of-band cutoff effect of the transmission and reflection layer, this results in a good absorption effect.

[0061] Conformal integrated skin for penetrating radiation under different incident angles: (e.g., interpolation loss within the band) Figure 8 As shown. Figure 8 This indicates that the metasurface has a low insertion loss (IL<1dB) within the band (2.8-3.2GHz). Furthermore, when the incident angle is 60°, the increase in insertion loss within the band is not significant, and a certain wave transmission effect can still be achieved.

[0062] The absorption rate of the conformal, transmissive integrated skin at different incident angles is as follows: Figure 9 As shown, the absorption rate is determined by S 11 Parameters and S 21 The absorption rate is determined by a combination of parameters, including S. 11 and S 21 The square of the parameter is inversely proportional. Figure 9 This indicates that the metasurface has a good absorption effect outside the band (8-12 GHz), and in particular, the absorption rate outside the band can reach a high level when the incident angle is 85°.

[0063] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0064] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A conformal, breathable, integrated skin, characterized in that, It consists of multiple periodically arranged metasurface units, including an impedance layer and a transmission / reflection layer. The transmission / reflection layer is disposed below the impedance layer, and a third support layer separates the transmission / reflection layer from the impedance layer. The impedance layer comprises a first absorption layer, a first support layer, a second absorption layer, a second support layer, and a third support layer, wherein: The first and second absorption layers are made of resistive thin film material. The sheet resistance of the resistive film in the first absorption layer is smaller than that in the second absorption layer. The first support layer, the second support layer and the third support layer are made of PMI foam material with low dielectric constant. The first absorbent layer, the first support layer, the second absorbent layer, and the second support layer form a mushroom-shaped three-dimensional structure. The first absorbent layer covers the top of the first support layer, the second support layer is located at the bottom of the first support layer, and the second absorbent layer covers the periphery of the second support layer. The mushroom-shaped three-dimensional structure is bonded to or embedded in the third support layer. The transmission and reflection layer comprises, in sequence, a first metal ring layer, a first dielectric substrate, a first patch layer, a fourth support layer, a second metal ring layer, a second dielectric substrate, a third metal ring layer, a fifth support layer, a second patch layer, a third dielectric substrate, and a fourth metal ring layer, wherein: The first, second, third, and fourth metal ring layers all use rectangular annular metal patches. The outer side length of the rectangular annular metal patches in the first and third metal ring layers is smaller than the side length of the transmission and reflection layer unit; the outer side length of the rectangular annular metal patches in the second and fourth metal ring layers is equal to the side length of the transmission and reflection layer unit. The fourth and fifth support layers are made of PMI foam material with high dielectric constant; The first and second patch layers each have four rectangular patches, each with a perforated structure at one corner. In the first and second patch layers, the four rectangular patches are arranged in a 2*2 matrix, forming a cross gap in the middle. The perforated structure of each layer is located at the four corners of the transmissive and reflective layer unit patch layer.

2. The conformal, breathable, integrated skin according to claim 1, characterized in that, The transmission and reflection layer is disposed 1 mm below the impedance layer.

3. The conformal, breathable, integrated skin according to claim 1, characterized in that, The sheet resistance of the resistive film in the first absorption layer is set to 150 Ω / m. 2 The sheet resistance of the resistive film in the second absorption layer is set to 500 Ω / m. 2 .

4. The conformal, breathable, integrated skin according to claim 1, characterized in that, The dielectric constants ε of the first support layer, the second support layer, and the third support layer r = 1.07, loss tangent tanδ = 0.

001.

5. The conformal, breathable, integrated skin according to claim 1, characterized in that, The dielectric constant ε of the fourth and fifth support layers r = 3.25, loss tangent tanδ = 0.

005.

6. The conformal, breathable, integrated skin according to claim 1, characterized in that, The first dielectric substrate, the second dielectric substrate, and the third dielectric substrate are all F4B dielectric substrates.

7. The conformal, breathable, integrated skin according to claim 1, characterized in that, The first and second support layers are formed by cutting grooves in a single piece of PMI foam material. The third support layer is cut into grooves according to the size of the second support layer, so that the second support layer is embedded into the third support layer.

8. The conformal, breathable, integrated skin according to claim 1, characterized in that, The first metal ring layer adopts a first rectangular annular metal patch, which is placed at the center of the transmission and reflection layer unit. The outer side length of the first rectangular annular metal patch is smaller than the side length of the transmission and reflection layer unit. The second metal ring layer adopts a second rectangular annular metal patch, which is placed at the center of the transmission and reflection layer unit. The outer side length of the second rectangular annular metal patch is equal to the side length of the transmission and reflection layer unit and coincides with the boundary of the transmission and reflection unit. The third metal ring layer adopts a third rectangular ring metal patch, which is placed at the center of the transmission and reflection layer unit. The outer side length of the third rectangular ring metal patch is equal to the side length of the transmission and reflection layer unit and coincides with the boundary of the transmission and reflection unit. The fourth metal ring layer adopts a fourth rectangular annular metal patch, which is placed at the center of the transmission and reflection layer unit. The outer side length of the fourth rectangular annular metal patch is equal to the side length of the first rectangular annular metal patch.

9. The conformal, breathable, integrated skin according to claim 1, characterized in that, The second patch layer has the same size parameters as the first patch layer.

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