A reconfigurable transparent wave absorber based on miura fold

Abstract

The application discloses a reconfigurable transparent wave absorber based on a miura fold, and relates to a transparent wave absorber. The application aims to solve the problems of a narrow variable absorption bandwidth, a small change amplitude and a small absorption angle of an existing reconfigurable wave absorber. The reconfigurable transparent wave absorber based on the miura fold is composed of a miura fold-shaped wave absorbing layer and a planar reflecting layer from top to bottom; or the reconfigurable transparent wave absorber based on the miura fold is a single miura fold-shaped wave absorbing layer.

Description

Technical Field

[0001] This invention relates to a transparent microwave absorber. Background Technology

[0002] With the development of microwave technology, the power of radio frequency equipment has increased dramatically, leading to a significant increase in electromagnetic radiation near specific areas such as airport control towers, mobile phone base stations, and radar stations. This poses threats to human health and interferes with communication systems. Absorbing materials can effectively absorb incident electromagnetic waves, thus mitigating electromagnetic pollution. On the other hand, in the military field, coating vehicle surfaces with absorbing materials can effectively improve their survivability and penetration capabilities. However, conventional absorbing materials are often optically opaque, making it difficult to meet the requirements of optically transparent applications such as optical windows, fairings, canopies, and solar panels.

[0003] Transparent microwave absorbers are materials that can effectively absorb incident electromagnetic waves and are transparent in the visible light band. They convert incident electromagnetic waves into heat or other energy by using an optically transparent structure with losses, thus achieving the purpose of absorbing electromagnetic waves and reducing scattering. On the one hand, transparent microwave absorbers are limited by the limits of absorption bandwidth and thickness. Designing transparent microwave absorbers with broadband absorption performance is both a long-term technical challenge and an urgent practical need.

[0004] On the other hand, most existing transparent absorbers share a common limitation: once manufactured, their absorption performance cannot be altered. This hinders their application in scenarios requiring dynamic control. Existing methods for dynamically controlling the function of electromagnetic devices primarily involve introducing external stimuli such as bias voltage, magnetic fields, and heating to control the electromagnetic properties of smart materials like liquid crystals and phase change materials, thereby achieving modifiable absorption characteristics. However, the adjustable range of these designs is usually limited by material properties, rendering them impractical. For example, they suffer from narrow absorption bandwidth (typically only around 1 GHz), small changes in absorptivity from absorption to reflection, and effectiveness only at certain incident angles. Summary of the Invention

[0005] The present invention aims to solve the problems of narrow variable absorption bandwidth, small change amplitude and small absorption angle of existing reconfigurable absorbers, and provides a reconfigurable transparent absorber based on Miura folding.

[0006] The reconfigurable transparent absorber based on Miura folding consists of an absorbing layer in the shape of Miura folding and a planar reflective layer from top to bottom; or the reconfigurable transparent absorber based on Miura folding is a single absorbing layer in the shape of Miura folding.

[0007] The aforementioned Miura folded-shaped absorbing layer is a Miura folded-shaped structure formed by attaching a transparent conductive film to a transparent substrate.

[0008] The beneficial effects of this invention are:

[0009] This invention proposes a reconfigurable transparent absorber based on Miura folding, which utilizes a transparent conductive film folded into a Miura fold shape. The shape can be changed under the action of external force, thereby achieving an adjustable design of electromagnetic absorption performance. At the same time, each parallelogram remains in a planar state during the application of external force, which is beneficial for the design of electromagnetic wave absorption.

[0010] This invention is based on the Miura folded reconfigurable transparent absorber, which can switch from absorption to reflection by changing its shape. When a planar reflective layer is set, the absorptivity changes from more than 80% to less than 10% under the ultra-wideband conditions of 4GHz to 40GHz, with an absorptivity change amplitude of more than 70%. When no planar reflective layer is set, the absorptivity of the reconfigurable absorber changes from about 70% to 49% under the ultra-wideband conditions of 5.5GHz to 40GHz, thus solving the problems of narrow variable absorption bandwidth and small change amplitude of reconfigurable absorbers.

[0011] This invention is based on the fact that the reconfigurable transparent absorber of Miura folding has good oblique incidence absorption performance when it is in the absorption state. When the TE wave is obliquely incident at less than 60°, the absorption rate can be maintained at more than 70%, and when the TM wave is obliquely incident at less than 60°, the absorption rate can be maintained at more than 90%, thus solving the problem of wide-angle absorption of the absorber.

[0012] This invention relates to a reconfigurable transparent absorber based on Miura folding. Attached Figure Description

[0013] Figure 1 This is a diagram of the folded structure of the reconfigurable transparent absorber based on Miura folding in Example 1 when β = 90°.

[0014] Figure 2 This is a diagram of the folded structure of the reconfigurable transparent absorber based on Miura folding in Example 1 when β = 180°.

[0015] Figure 3 This is a schematic diagram of the structure in Example 1 where the folded-shape absorbing layer of Miura is fixed to the reflective layer on a plane by a thin thread;

[0016] Figure 4 The absorption rate of the reconfigurable transparent absorber based on Miura folding in Example 1 is shown under different folding states and different polarizations under vertical incident conditions. 1 is the x-polarization absorption (β = 90°), 2 is the y-polarization absorption (β = 90°), and 3 is the overlap curve of x-polarization absorption (β = 180°) and y-polarization absorption (β = 180°).

[0017] Figure 5The absorption rate of the reconfigurable transparent absorber based on Miura folding in Example 1 under the condition of oblique incidence of TE wave in the absorption state (β=90°) is 1 for TE15°, 2 for TE30°, 3 for TE45°, and 4 for TE60°.

[0018] Figure 6 The absorption rate of the reconfigurable transparent absorber based on Miura folding in Example 1 under the condition of oblique incidence of TM waves in the absorption state (β=90°) is 1 for TM15°, 2 for TM30°, 3 for TM45°, and 4 for TM60°.

[0019] Figure 7 This is a diagram of the folded structure of the reconfigurable transparent absorber based on Miura folding when β = 90°, as shown in Example 2.

[0020] Figure 8 This is a diagram of the folded structure of the reconfigurable transparent absorber based on Miura folding in Example 2 when β = 180°.

[0021] Figure 9 Example 2 shows the absorption rate of the reconfigurable transparent absorber based on Miura folding under different folding states and different polarizations under vertical incident conditions. 1 is the x-polarization absorption (β = 90°), 2 is the y-polarization absorption (β = 90°), and 3 is the overlap curve of x-polarization absorption (β = 180°) and y-polarization absorption (β = 180°).

[0022] Figure 10 Example 2 shows the absorption rate of the reconfigurable transparent absorber based on Miura folding under the condition of oblique incidence of TE waves in the absorption state (β=90°). 1 represents TE15°, 2 represents TE30°, 3 represents TE45°, and 4 represents TE60°.

[0023] Figure 11 The absorption rate of the reconfigurable transparent absorber based on Miura folding in Example 2 under the condition of oblique incidence of TM waves in the absorption state (β=90°) is 1 for TM15°, 2 for TM30°, 3 for TM45°, and 4 for TM60°. Detailed Implementation

[0024] Specific implementation method one: This implementation method is a reconfigurable transparent absorber based on Miura folding. The reconfigurable transparent absorber based on Miura folding is composed of a Miura folding-shaped absorbing layer and a planar reflective layer from top to bottom; or the reconfigurable transparent absorber based on Miura folding is a single Miura folding-shaped absorbing layer.

[0025] The aforementioned Miura folded-shaped absorbing layer is a Miura folded-shaped structure formed by attaching a transparent conductive film to a transparent substrate.

[0026] The beneficial effects of this embodiment are:

[0027] This embodiment proposes a reconfigurable transparent absorber based on Miura folding, which utilizes a transparent conductive film folded into a Miura folding shape. The shape can be changed under the action of external force, thereby achieving an adjustable design of electromagnetic absorption performance. At the same time, each parallelogram remains in a planar state during the application of external force, which is beneficial for the design of electromagnetic wave absorption.

[0028] This embodiment is based on the Miura folded reconfigurable transparent absorber, which can switch from absorption to reflection by changing its shape. When a planar reflective layer is provided, the absorptivity changes from more than 80% to less than 10% under the ultra-wideband conditions of 4GHz to 40GHz, with an absorptivity change amplitude of more than 70%. When no planar reflective layer is provided, the absorptivity of the reconfigurable absorber changes from around 70% to 49% under the ultra-wideband conditions of 5.5GHz to 40GHz, thus solving the problems of narrow variable absorption bandwidth and small change amplitude of the reconfigurable absorber.

[0029] This embodiment is based on the fact that the reconfigurable transparent absorber of Miura folding has good oblique incidence absorption performance when it is in the absorption state. When the TE wave oblique incidence is less than 60°, the absorption rate can be maintained above 70%, and when the TM wave oblique incidence is less than 60°, the absorption rate can be maintained above 90%, thus solving the problem of wide-angle absorption of the absorber.

[0030] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the transparent conductive film is made of one or a composite of several of the following: transparent conductive oxide, silver nanowires, graphene, transparent conductive polymer, and metal. Everything else is the same as in Specific Implementation Method One.

[0031] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the thickness of the transparent conductive film is 10 nm to 1 μm. Everything else is the same as in Specific Implementation Method One or Two.

[0032] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the sheet resistance of the transparent conductive film is 1Ω / sq to 400Ω / sq. Everything else is the same as in Specific Implementation Methods One to Three.

[0033] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that the transparent substrate is made of polyethylene terephthalate, polypropylene, polyvinyl chloride, ABS, thermoplastic polyurethane elastomer rubber, polystyrene, or transparent nylon. Everything else is the same as in Specific Implementation Methods One to Four.

[0034] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the thickness of the transparent substrate is 0.07mm to 3mm. Everything else is the same as in Specific Implementation Methods One to Five.

[0035] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that the reflective layer of the plane is made of one or a composite of several of the following: transparent conductive oxide, silver nanowires, graphene, transparent conductive polymer, and metal. Everything else is the same as in Specific Implementation Methods One to Six.

[0036] Specific Implementation Method Eight: This implementation method differs from one of Specific Implementation Methods One to Seven in that the thickness of the reflective layer on the plane is 10 nm to 1 μm. Everything else is the same as in Specific Implementation Methods One to Seven.

[0037] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that the surface resistivity of the reflective layer of the plane is 0.01Ω / sq to 20Ω / sq. Everything else is the same as in Specific Implementation Methods One to Eight.

[0038] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that the Miura folded-shaped absorbing layer is fixed to the planar reflective layer using grooves, fine lines, or reusable adhesive. Otherwise, it is the same as Specific Implementation Methods One to Nine.

[0039] The beneficial effects of the present invention are verified using the following embodiments:

[0040] Example 1:

[0041] A reconfigurable transparent absorber based on Miura folding consists of an absorbing layer in the shape of Miura folding and a planar reflective layer from top to bottom; and the absorbing layer in the shape of Miura folding is fixed to the planar reflective layer by thin wires.

[0042] The aforementioned Miura folded-shaped absorbing layer is a Miura folded-shaped structure formed by attaching a transparent conductive film to a transparent substrate.

[0043] The transparent conductive film is made of ITO film; the thickness of the transparent conductive film is 20nm; and the sheet resistance of the transparent conductive film is 10Ω / sq.

[0044] The transparent substrate is made of PET; the thickness of the transparent substrate is 0.125 mm; and the sheet resistance of the transparent conductive film is 150 Ω / sq.

[0045] The reflective layer of the plane is made of ITO-PET film; the thickness of the reflective layer of the plane is 260nm; and the surface resistivity of the reflective layer of the plane is 10Ω / sq.

[0046] Figure 3This is a schematic diagram of the structure of the Miura folded-shaped absorbing layer fixed to the planar reflective layer by a thin thread in Embodiment 1. The Miura folded-shaped absorbing layer is fixed to the planar reflective layer by a thin thread. Specifically, a circular hole with a diameter of less than 0.2 mm is first made at each inflection point where the absorbing layer and the reflective layer come into contact. The thin thread is then passed through the reflective layer-absorbing layer-reflective layer-absorbing layer in sequence, and this cycle is repeated, so that the absorbing layer is fixed to the reflective layer. The switching from the absorbing state to the reflective state is achieved by controlling the release or tightening of the thin thread.

[0047] The aforementioned Miura fold is a periodic structure composed of multiple folding units. Each folding unit consists of four parallelograms arranged in two rows. In each parallelogram, the longer side is 'a', the shorter side is 'b', and the acute angle is 'α'. Adjacent parallelograms in the same row within a unit are mirror images of each other, and the angle of the dihedral angle formed is 'β'. The folding state of adjacent parallelograms can be defined by the dihedral angle 'β'. The values ​​of a = 35.35 mm, b = 25 mm, and α = 45° are specified.

[0048] Figure 1 This is a diagram of the folded structure of the reconfigurable transparent absorber based on Miura folding in Example 1 when β = 90°. Figure 2 This is a diagram of the folded structure of the reconfigurable transparent absorber based on Miura folding in Example 1 when β = 180°. Figure 4 The figures for Example 1 show the absorption rates of the reconfigurable transparent absorber based on Miura folding under different folding states and polarizations under vertical incidence conditions. Figure 1 shows the x-polarization absorption (β = 90°), Figure 2 shows the y-polarization absorption (β = 90°), and Figure 3 shows the overlap curves of x-polarization absorption (β = 180°) and y-polarization absorption (β = 180°). When β = 90°, the absorber is in an absorbing state, and x-polarized vertical incidence can achieve over 80% absorption in the range of 4.2 GHz to 40 GHz, with a fractional bandwidth of 161%. When y-polarized vertical incidence, it can achieve over 90% absorption in the range of 5.12 GHz to 40 GHz, with a fractional bandwidth of 154%. When β = 180°, the absorber is in a reflecting state, and the absorption rate is less than 10% in the range of 0 GHz to 40 GHz for both x-polarized and y-polarized vertical incidence. When switching from the absorption state to the reflection state, the reconfigurable absorber reduces its absorption rate from over 80% to below 10% under the ultra-wideband conditions of 4GHz to 40GHz, with the amplitude of the absorption rate change reaching over 70%. This solves the problem of narrow variable absorption bandwidth and small amplitude of change in reconfigurable absorbers.

[0049] Figure 5 The absorption rate of the reconfigurable transparent absorber based on Miura folding in Example 1 under the condition of oblique incidence of TE wave in the absorption state (β=90°) is 1 for TE15°, 2 for TE30°, 3 for TE45°, and 4 for TE60°. Figure 6The figure shows the absorption rate of the reconfigurable transparent absorber based on Miura folding in Example 1 under oblique incidence of TM waves in the absorption state (β = 90°). 1 represents TM 15°, 2 represents TM 30°, 3 represents TM 45°, and 4 represents TM 60°. As can be seen from the figure, the reconfigurable transparent absorber based on Miura folding in Example 1 exhibits excellent oblique incidence absorption performance in the absorption state. When the oblique incidence of TE waves is less than 60°, the absorption rate can be maintained above 80%, and when the oblique incidence of TM waves is less than 60°, the absorption rate can be maintained above 90%, thus solving the problem of wide-angle absorption in absorbers.

[0050] Example 2: This example differs from Example 1 in that the planar reflective layer is eliminated, and the reconfigurable transparent absorber based on the Miura fold is a separate absorber layer with a Miura fold shape. Everything else is the same as in Example 1.

[0051] Figure 7 This is a diagram of the folded structure of the reconfigurable transparent absorber based on Miura folding in Example 2, when β = 90°. Figure 8 This is a diagram of the folded structure of the reconfigurable transparent absorber based on Miura folding in Example 2 when β = 180°. Figure 9 Example 2 shows the absorption rate of the reconfigurable transparent absorber based on Miura folding under different folding states and different polarizations under vertical incidence conditions. 1 represents x-polarization absorption (β = 90°), 2 represents y-polarization absorption (β = 90°), and 3 represents the overlap curve of x-polarization absorption (β = 180°) and y-polarization absorption (β = 180°). When β = 90°, the absorber is in an absorbing state, and x-polarized vertical incidence can achieve absorption of over 65.41% in the range of 5.56 GHz to 40 GHz, with a fractional bandwidth of 151%. When y-polarized waves are vertically incident, absorption of over 74.7% can be achieved in the range of 5.12 GHz to 40 GHz, with a fractional bandwidth of 153.2%. When β = 180°, the absorber is in a reflecting state, and the absorption rate is 49% in the range of 0–40 GHz for both x-polarized and y-polarized vertical incidence. When switching from the absorption state to the reflection state, the reconfigurable absorber's absorption rate changes from around 70% to 49% under the ultra-wideband conditions of 5.5GHz to 40GHz, solving the problem of narrow variable absorption bandwidth of the reconfigurable absorber.

[0052] Figure 10 Example 2 shows the absorption rate of the reconfigurable transparent absorber based on Miura folding under the condition of oblique incidence of TE waves in the absorption state (β=90°). 1 represents TE15°, 2 represents TE30°, 3 represents TE45°, and 4 represents TE60°. Figure 11The figure shows the absorption rate of the reconfigurable transparent absorber based on Miura folding in Example 2 under oblique incidence of TM waves in the absorption state (β = 90°). 1 represents TM 15°, 2 represents TM 30°, 3 represents TM 45°, and 4 represents TM 60°. As can be seen from the figure, the reconfigurable transparent absorber based on Miura folding in Example 2 exhibits excellent oblique incidence absorption performance in the absorption state. When the oblique incidence of TE waves is less than 60°, the absorption rate can be maintained above 72%, and when the oblique incidence of TM waves is less than 60°, the absorption rate can be maintained above 90%, solving the problem of wide-angle absorption in absorbers.

Claims

1. A reconfigurable transparent absorber based on Miura folding, characterized in that... The reconfigurable transparent absorber based on Miura folding consists of an absorbing layer with a Miura folding shape and a planar reflective layer from top to bottom. The aforementioned Miura folded-shaped absorbing layer is a Miura folded-shaped structure formed by attaching a transparent conductive film to a transparent substrate. The sheet resistance of the transparent conductive film is 150Ω / sq~400Ω / sq; The thickness of the transparent substrate is 0.07mm to 3mm; The thickness of the reflective layer on the plane is 10 nm to 1 μm; The surface resistivity of the reflective layer of the plane is 0.01Ω / sq to 20Ω / sq; The aforementioned Miura fold is a periodic structure composed of multiple folding units. Each folding unit consists of four parallelograms arranged in two rows. Adjacent parallelograms in the same row within a unit are mirror images of each other, and the dihedral angle formed is β. By changing β (β=90° or β=180°), the switching from the absorption state to the reflection state is achieved. Under the switching from the absorption state to the reflection state, the reconfigurable absorber changes its absorptivity from over 80% to below 10% in the ultra-wideband condition of 4GHz~40GHz, with an absorptivity change amplitude of over 70%.

2. The reconfigurable transparent absorber based on Miura folding as described in claim 1, characterized in that... The transparent conductive film is made of one or a composite of several of the following: transparent conductive oxide, silver nanowires, graphene, transparent conductive polymer and metal.

3. The reconfigurable transparent absorber based on Miura folding according to claim 1, characterized in that... The thickness of the transparent conductive film is 10 nm to 1 μm.

4. A reconfigurable transparent absorber based on Miura folding as described in claim 1, characterized in that... The transparent substrate is made of polyethylene terephthalate, polypropylene, polyvinyl chloride, ABS, thermoplastic polyurethane elastomer rubber, polystyrene, or transparent nylon.

5. A reconfigurable transparent absorber based on Miura folding as described in claim 1, characterized in that... The reflective layer of the plane is made of one or a combination of several of the following materials: transparent conductive oxide, silver nanowires, graphene, transparent conductive polymer and metal.

6. A reconfigurable transparent absorber based on Miura folding as described in claim 1, characterized in that... The folded absorbing layer of Miura is fixed to the flat reflective layer by grooves, fine lines, or reusable adhesive.

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