High-cut-off absorbing and transmitting integrated reconfigurable skin

Abstract

The invention discloses a high-cut-off absorption and transmission integrated reconfigurable skin which is composed of a plurality of tunable metasurface units arranged periodically and comprises an impedance layer, a foam filling layer and a reconfigurable metasurface layer, the foam filling layer is located on the lower side of the impedance layer, and the reconfigurable metasurface layer is located on the lower side of the foam filling layer. The impedance layer comprises a first absorption layer and a second absorption layer which are sequentially arranged from top to bottom; the reconfigurable metasurface layer comprises a first double-layer metal structure, a first supporting layer, a second double-layer metal structure, a second supporting layer and a third double-layer metal structure which are sequentially arranged from top to bottom. According to the invention, the three-dimensional impedance layer and the two-dimensional reconfigurable metasurface layer are combined, and the two advantages of high angle stability of a three-dimensional structure and low profile of a two-dimensional structure are utilized at the same time, so that the performance of large-angle wave absorption is achieved at a relatively low profile height.

Description

Technical Field

[0001] The present invention relates to an electromagnetic stealth technology, and in particular to a high-cutoff, absorbent and penetrable integrated reconfigurable skin. Background Art

[0002] Electromagnetic stealth materials are of great significance in modern electronic systems, effectively protecting sensitive electronic equipment from external interference signals and ensuring the normal operation and safety of the system. Traditional electromagnetic stealth materials, such as ferrites, polycrystalline fibers, and graphite fibers, while having significant functions, are bulky, heavy, and expensive, limiting their widespread use in practical applications. To overcome these shortcomings, in recent years, researchers have begun to turn to the use of novel devices based on artificial electromagnetic structures, such as absorbers and diffuse scatterers, as new electromagnetic stealth materials. To date, traditional artificial electromagnetic stealth materials, while performing well within specific frequency ranges, suffer from the limitation of limited absorption angles. For example, many existing absorbing materials often have a significantly reduced absorption effect at high angles of incidence, which poses a challenge to the stealth protection of electronic systems. Therefore, the development of a reconfigurable absorptive-transmissive metasurface structure with high-angle absorption capabilities is urgent and has broad application prospects. Summary of the Invention

[0003] The purpose of the present invention is to provide a high-cutoff absorptive-transmissive integrated reconfigurable skin to realize the switchable wave-transmitting state and the absorptive-shielding state of the metasurface at different frequency bands under different external bias voltages.

[0004] The technical solution to achieve the purpose of the present invention is: a high-cutoff, absorbent and reconfigurable skin, composed of a plurality of periodically arranged tunable metasurface units, including an impedance layer, a foam filling layer and a reconfigurable metasurface layer, wherein the foam filling layer is located under the impedance layer, and the reconfigurable metasurface layer is located under the foam filling layer, wherein: The impedance layer includes a first absorption layer and a second absorption layer arranged sequentially from top to bottom; The reconfigurable metasurface layer includes a first double-layer metal structure, a first supporting layer, a second double-layer metal structure, a second supporting layer and a third double-layer metal structure, which are arranged in sequence from top to bottom.

[0005] Furthermore, the first absorption layer and the second absorption layer are based on a low dielectric constant PMI foam material, and the overall composition is a mushroom-shaped three-dimensional unit structure, wherein the first absorption layer is composed of a supporting PMI foam and a rectangular resistor film covering it; the second absorption layer is composed of a supporting PMI foam and a resistor film around it, the square resistance value of the resistor film of the first absorption layer is smaller than the square resistance value of the resistor film of the second absorption layer, when the electromagnetic wave with a small incident angle is incident, the first absorption layer plays the main absorption role, and when the electromagnetic wave with a large angle or grazing incidence is incident, the second absorption layer plays the main absorption role.

[0006] Furthermore, the dielectric constant ε of the PMI foam material used in the impedance layer is r = 1.07, loss tangent tan δ = 0.001.

[0007] Furthermore, the first double-layer metal structure includes a supporting F4B dielectric substrate and a square ring-shaped metal patch array covering both sides of the F4B dielectric substrate.

[0008] Furthermore, the second double-layer metal structure includes a supporting F4B dielectric substrate and a cross-shaped metal patch array covering both sides of the F4B dielectric substrate. The cross-shaped metal patches are connected by inductors or PIN diodes. The inductors on the same side of the F4B dielectric substrate are arranged in the same direction, and the PIN diodes are arranged in a direction orthogonal to the inductors. The inductors and PIN diodes are arranged in the opposite manner between the cross-shaped metal patches on the other side of the F4B dielectric substrate.

[0009] Furthermore, the third double-layer metal structure includes a supporting F4B dielectric substrate and a square ring-shaped metal patch array covering both sides of the F4B dielectric substrate.

[0010] Furthermore, the first supporting layer and the second supporting layer are made of PMI foam material with a high dielectric constant, and the dielectric constant ε r = 3.25, loss tangent tan δ = 0.005.

[0011] Furthermore, the feeding network between multiple periodically arranged tunable metasurface units is in parallel form, and the inductors arranged in the same direction are connected in series to connect adjacent cross-shaped metal patches to form a DC bias line. The adjacent DC bias lines are alternately loaded with high and low levels in turn, which can feed the diodes arranged orthogonally to the inductors in parallel.

[0012] Furthermore, the foam filling layer is bonded to the lower part of the impedance layer through epoxy resin, and the first double-layer metal structure, the first supporting layer, the second double-layer metal structure, the second supporting layer, and the third double-layer metal structure are bonded to each other from top to bottom through epoxy resin and bonded to the lower side of the foam filling layer.

[0013] Furthermore, when low-frequency electromagnetic waves are incident, the electromagnetic waves incident on the metasurface cannot produce sufficiently strong resonance, and the overall structure presents a high-impedance state, which is in a state of transmitting electromagnetic waves. By changing the DC bias voltage of the PIN diode, the metasurface's wave transmission band can be switched. When high-frequency electromagnetic waves are incident, the electromagnetic waves incident on the metasurface resonate with the transmissive reflective layer. At this time, the transmissive reflective layer is in a reflective state, and the absorption layer absorbs the incident electromagnetic waves and the electromagnetic waves reflected by the transmissive reflective surface at the same time. The overall structure is in an absorption state and has a cutoff effect. At the same time, it maintains the wave absorption efficiency when the electromagnetic waves are incident at a large angle.

[0014] Compared with the existing technology, the significant advantage of the present invention is that it combines a three-dimensional impedance layer with a two-dimensional reconfigurable metasurface layer, and simultaneously utilizes the two advantages of high angular stability of the three-dimensional structure and low profile of the two-dimensional structure, achieving large-angle absorption performance at a relatively low profile height. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is the main view of the high-cutoff, absorbent and reconfigurable skin unit structure; Figure 2 This is an oblique view of the high-cutoff, absorbent and reconfigurable skin unit structure; Figure 3 Schematic diagram of a high-cutoff, absorbent, and reconfigurable skin; Figure 4 Schematic diagram of the impedance layer structure; Figure 5 Schematic diagram of the reconfigurable metasurface layer; Figure 6 The in-band S21 parameters of the high-cutoff absorbent integrated reconfigurable skin in two states; Figure 7 The S21 parameters of the high-cutoff integrated absorbent and penetrating reconfigurable skin in the L-Ku band at different incident angles in two states; Figure 8 The absorption rate of the high-cutoff absorber-transmitter reconfigurable skin to TM polarized waves at large angles of incidence; Explanation of symbols: 1-impedance layer, 2-reconfigurable metasurface layer, 3-foam filling layer, 4-low square resistance resistor film, 5-high square resistance resistor film, 6-low dielectric constant PMI foam, 7-high dielectric constant PMI foam, 8-double-layer metal structure, 9-first double-layer metal structure, 10-first support layer, 11-second double-layer metal structure, 12-second support layer, 13-third dielectric substrate, 14-third double-layer metal structure. DETAILED DESCRIPTION

[0016] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0017] like Figure 1 、 2 As shown in Figure 3, the high-cutoff absorbent and permeable integrated reconfigurable skin includes multiple periodically arranged metasurface units, which are composed of an impedance layer 1, a reconfigurable metasurface layer 2 and a foam filling layer 3.

[0018] like Figure 4 As shown, the impedance layer 1 comprises a first absorbent layer and a second absorbent layer, arranged sequentially from top to bottom. The first and second absorbent layers are based on PMI foam material and form a mushroom-shaped three-dimensional unit structure. The first absorbent layer forms the top portion of the three-dimensional unit structure, while the second absorbent layer forms the bottom portion of the three-dimensional unit structure. The second absorbent layer is narrower than the first absorbent layer, thus forming a mushroom-shaped impedance layer.

[0019] Furthermore, the impedance layer 1 comprises a low-square-resistance resistor film 4, a high-square-resistance resistor film 5, and a low-dielectric-constant PMI foam 6. The first absorption layer comprises a supporting PMI foam and the low-square-resistance resistor film 4 covering it; the second absorption layer comprises a supporting PMI foam and the high-square-resistance resistor film 5 surrounding it. When electromagnetic waves are incident at a relatively small angle, the first absorption layer primarily absorbs them; when electromagnetic waves are incident at a large angle or with grazing incidence, the second absorption layer primarily absorbs them. The PMI foam material used in the impedance layer is a low-dielectric-constant material (ε r = 1.07, tan δ = 0.001).

[0020] like Figure 5As shown, the reconfigurable metasurface layer 2 is composed of a first double-layer metal structure 9, a first supporting layer 10, a second double-layer metal structure 11, a second supporting layer 12, and a third double-layer metal structure 13, which are bonded to each other from top to bottom using epoxy resin. The first double-layer metal structure includes a F4B dielectric substrate that plays a supporting role and square ring metal patches covering both sides of the F4B dielectric substrate. The second double-layer metal structure includes a F4B dielectric substrate that plays a supporting role and a cross-shaped metal patch array covering both sides of the F4B dielectric substrate. The cross-shaped metal patches are connected by inductors or PIN diodes. The inductors and PIN diodes between the cross-shaped metal patches are arranged in the same direction on the same side of the F4B dielectric substrate, and the diodes are arranged in a direction orthogonal to the inductors; between the cross-shaped metal patches on the other side of the F4B dielectric substrate, the arrangement of the inductors and PIN diodes is opposite. For example, if the diodes on the upper side of the F4B dielectric substrate are arranged horizontally, the inductors on the upper side are arranged vertically, and the diodes on the lower side of the F4B dielectric substrate are arranged vertically and the inductors are arranged horizontally. The third double-layer metal structure is the same as the first double-layer metal structure. The support layer uses a high dielectric constant PMI foam material (ε r = 3.25, tan δ = 0.005). By applying a DC bias voltage to the cross-shaped metal patch array of the second double-layer metal structure of the reconfigurable metasurface, the high-cutoff, integrated absorptive and transmissive reconfigurable skin can be switched from a broadband transmission range of 2.9-3.3 GHz to a narrowband transmission range around 3.5 GHz. In particular, due to its multi-layered structure, the structure exhibits excellent out-of-band cutoff performance, effectively preventing high-frequency electromagnetic waves from passing through the structure.

[0021] The inductors arranged in the same direction on the second double-layer metal structure are connected in series to connect adjacent cross-shaped metal patches to form a DC bias line. The adjacent DC bias lines are alternately loaded with high and low levels in sequence, which can feed the diodes arranged orthogonally to the inductors in parallel.

[0022] The high-cutoff, integrated absorbent and reconfigurable skin has good angular stability. The impedance layer adopts a mushroom-shaped three-dimensional structure, which can effectively meet the absorption requirements of electromagnetic waves with large oblique incidence. When the incident out-of-band electromagnetic waves are normal incidence or incident at a smaller angle, the first absorption layer plays a major role. When the incident angle is larger, the second absorption layer plays a major role.

[0023] The transmissive reflective layer is designed to transmit waves within the band and reflect outside the band. Therefore, when a low-frequency electromagnetic wave is incident, the electromagnetic wave incident on the metasurface cannot produce a sufficiently strong resonance, and the overall structure is in a high-impedance state and is in a state of transmitting electromagnetic waves. By changing the DC bias voltage of the PIN diode, the wave transmission band of the metasurface is switched; when a high-frequency electromagnetic wave is incident, the electromagnetic wave incident on the metasurface resonates with the transmissive reflective layer. At this time, the transmissive reflective layer is in a reflective state, and the absorption layer simultaneously absorbs the incident electromagnetic wave and the electromagnetic wave reflected by the transmissive reflective surface. The overall structure is in an absorption state, has a high cutoff effect, and can maintain excellent wave absorption performance when the electromagnetic wave is incident at a larger angle.

[0024] In summary, the present invention also has a switchable filtering effect on spatial electromagnetic waves. That is, for electromagnetic waves within the operating frequency band, by switching the operating state of the reconfigurable metasurface, electromagnetic waves of different frequencies can pass through with low insertion loss, without affecting the receiving / transmitting performance of the RF front-end antenna. For electromagnetic waves outside the band, the metasurface will be in an absorbing state to achieve the effect of reducing scattering. In particular, the metasurface still has a good absorption effect on electromagnetic waves incident at large angles. The present invention can realize the switchable wave-transmitting state and absorption-shielding state of the metasurface in different frequency bands under different external bias voltages. Example

[0025] In order to verify the effectiveness of the solution of the present invention, the following experiment was conducted.

[0026] The in-band insertion loss of the high-cutoff absorbent-transmitter reconfigurable skin at different incident angles is as follows: Figure 6 shown. Figure 6 It shows that the high-cutoff integrated absorbent and transmittant reconfigurable skin has low insertion loss within the band and can switch between a broadband wave-transmitting state of 2.9-3.3 GHz and a narrowband wave-transmitting state near 3.5 GHz.

[0027] The transmission coefficient of the high-cutoff absorbent-transmitter reconfigurable skin at different incident angles is as follows: Figure 7 shown. Figure 7 The results show that the high-cutoff integrated absorbent and penetrating reconfigurable skin has good in-band high wave transmission and high out-band high cutoff effect. In particular, it maintains good cutoff performance under large-angle grazing incidence.

[0028] The absorption rate of the high-cutoff absorbent-transmitting reconfigurable skin at different incident angles is as follows: Figure 8 shown. Figure 8 The results show that the high-cutoff absorbent-transmitter reconfigurable skin has a good absorbing effect in the X-band (8-12 GHZ). In particular, when the incident angle is 85°, the absorption rate of the TM plan wave can reach a high level.

[0029] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0030] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A high-cutoff, breathable, integrated reconfigurable skin, characterized in that: It is composed of multiple periodically arranged tunable metasurface units, including an impedance layer, a foam filling layer and a reconfigurable metasurface layer. The foam filling layer is located under the impedance layer, and the reconfigurable metasurface layer is located under the foam filling layer. The impedance layer includes a first absorption layer and a second absorption layer arranged sequentially from top to bottom; The reconfigurable metasurface layer includes a first double-layer metal structure, a first supporting layer, a second double-layer metal structure, a second supporting layer and a third double-layer metal structure, which are arranged in sequence from top to bottom.

2. The high-cutoff, breathable, integrated reconfigurable skin according to claim 1, characterized in that: The first absorption layer and the second absorption layer are based on a low dielectric constant PMI foam material, and the overall composition is a mushroom-shaped three-dimensional unit structure, wherein the first absorption layer is composed of a supporting PMI foam and a rectangular resistive film covering it; the second absorption layer is composed of a supporting PMI foam and a resistive film around it. The square resistance value of the resistive film of the first absorption layer is smaller than the square resistance value of the resistive film of the second absorption layer. When an electromagnetic wave with a small incident angle is incident, the first absorption layer plays the main absorption role. When an electromagnetic wave with a large angle or grazing incidence is incident, the second absorption layer plays the main absorption role.

3. The high-cutoff, breathable, integrated reconfigurable skin according to claim 2, characterized in that: The dielectric constant ε of the PMI foam material used in the impedance layer r = 1.07, loss tangent tan δ = 0.

001.

4. The high-cutoff, breathable, integrated reconfigurable skin according to claim 1, characterized in that: The first double-layer metal structure includes a supporting F4B dielectric substrate and a square ring metal patch array covering both sides of the F4B dielectric substrate.

5. The high-cutoff, breathable, integrated reconfigurable skin according to claim 1, characterized in that: The second double-layer metal structure includes a supporting F4B dielectric substrate and a cross-shaped metal patch array covering both sides of the F4B dielectric substrate. The cross-shaped metal patches are connected by inductors or PIN diodes. The inductors on the same side of the F4B dielectric substrate are arranged in the same direction, and the PIN diodes are arranged in a direction orthogonal to the inductors. The inductors and PIN diodes are arranged in the opposite manner between the cross-shaped metal patches on the other side of the F4B dielectric substrate.

6. The high-cutoff, breathable, integrated reconfigurable skin according to claim 1, characterized in that: The third double-layer metal structure includes a supporting F4B dielectric substrate and a square ring metal patch array covering both sides of the F4B dielectric substrate.

7. The high-cutoff, breathable, integrated reconfigurable skin according to claim 1, characterized in that: The first supporting layer and the second supporting layer are made of PMI foam material with high dielectric constant, and the dielectric constant ε r = 3.25, loss tangent tan δ =0.

005.

8. The high-cutoff, breathable, integrated reconfigurable skin according to claim 5, characterized in that: The feeding network between multiple periodically arranged tunable metasurface units is in parallel form. The inductors arranged in the same direction are connected in series, connecting adjacent cross-shaped metal patches to form a DC bias line. The adjacent DC bias lines are alternately loaded with high and low levels in sequence, which can feed the diodes arranged orthogonally to the inductors in parallel.

9. The reconfigurable breathable and penetrable metasurface according to claim 1, characterized in that: The foam filling layer is bonded to the lower part of the impedance layer through epoxy resin, and the first double-layer metal structure, the first supporting layer, the second double-layer metal structure, the second supporting layer, and the third double-layer metal structure are bonded to each other from top to bottom through epoxy resin and bonded to the lower side of the foam filling layer.

10. The reconfigurable breathable and penetrable metasurface according to claim 1, characterized in that: When low-frequency electromagnetic waves are incident, the electromagnetic waves incident on the metasurface cannot produce sufficiently strong resonance, and the overall structure presents a high-impedance state, which is in a state of transmitting electromagnetic waves. By changing the DC bias voltage of the PIN diode, the wave transmission band of the metasurface can be switched. When high-frequency electromagnetic waves are incident, the electromagnetic waves incident on the metasurface resonate with the transmissive reflective layer. At this time, the transmissive reflective layer is in a reflective state, and the absorption layer absorbs the incident electromagnetic waves and the electromagnetic waves reflected by the transmissive reflective surface at the same time. The overall structure is in an absorption state and has a cutoff effect. At the same time, it maintains the wave absorption efficiency when the electromagnetic waves are incident at a large angle.

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