A flexible, light-transmitting, broadband absorbing structure

Abstract

The present invention relates to a flexible, light-transmitting, broadband absorbing structure comprising at least one absorbing shielding layer, encapsulated by a flexible, light-transmitting material. The shielding layer is composed of an array of nested circular rings, whose transmittance can be controlled by adjusting the inner and outer diameters of the rings. The structure is simple, addressing the low visible and infrared transmittance issues associated with electromagnetic absorbers made from opaque conductive materials. Visible and infrared transmittance is adjustable and exceeds 30%, while absorption rates reach over 80%, and the absorption bandwidth is over 10 times the lowest frequency.

Description

Technical Field

[0001] The invention relates to a flexible light-transmitting broadband wave-absorbing structure, belonging to the field of electromagnetic technology. Background Art

[0002] Absorbing structures are key materials in defense, military, and civilian technology applications, including military stealth, microwave anechoic chambers, microwave communications, electromagnetic information leakage protection, electromagnetic interference protection, and electromagnetic radiation protection. In recent years, with the advancement of electromagnetic shielding and stealth technologies, research on absorbers has garnered increasing attention. To meet the needs of diverse application scenarios, good flexibility and light transmission are increasingly becoming design requirements for broadband absorbers. However, a single layer of absorbing coating often fails to meet the light transmission requirements in many scenarios. Summary of the Invention

[0003] The purpose of the present invention is to solve the problem of low visible light or infrared light transmittance of existing absorbing structures and to provide a flexible, light-transmitting, broadband absorbing structure.

[0004] The present invention adopts the following technical solution: a flexible light-transmitting broadband wave-absorbing structure, comprising at least one wave-absorbing shielding layer, the outer side of which is wrapped with a transparent flexible packaging layer;

[0005] The wave-absorbing shielding layer is composed of an array of mutually nested circular rings, and the light transmittance of the wave-absorbing shielding layer can be determined by adjusting the inner and outer diameters of the circular rings.

[0006] Furthermore, the wave-absorbing shielding layer is formed by multiple rows of horizontal rings and vertical rings nested and connected with each other. A row of vertical rings is provided between two adjacent rows of horizontal rings to connect the adjacent rings into a wave-absorbing shielding layer with a certain area. The horizontal rings in each row are placed overlapping with each other.

[0007] Furthermore, the wave-absorbing shielding layer is made of an opaque flexible conductive material.

[0008] Furthermore, the flexible conductive material is carbon black / polydimethylsiloxane, carbon nanotube / polydimethylsiloxane, graphene / polydimethylsiloxane, poly(3,4-ethylenedioxythiophene) / polydimethylsiloxane or conductive rubber.

[0009] Furthermore, the thickness of the wave-absorbing shielding layer is 10-50 mm, the relative dielectric constant is 5-20, and the conductivity is set to 1-100 S / m;

[0010] Furthermore, the flexible packaging layer is made of transparent polydimethylsiloxane, vulcanized silicone rubber or polyethylene terephthalate.

[0011] Furthermore, the thickness of the flexible encapsulation layer exceeds the thickness of the wave-absorbing shielding layer by 1-10 mm, the relative dielectric constant is 1-3, and the loss tangent value is less than 0.05.

[0012] Beneficial effects of the present invention:

[0013] (1) The wave-absorbing shielding layer of the present invention is formed by winding a plurality of circular rings with each other. The ratio of the circular ring to the hollow portion can be adjusted by adjusting the size of the inner diameter and the outer diameter of the circular ring. The surface adopts a transparent flexible packaging layer. During use, it has a high light transmittance and can adjust the visible light transmittance to be generally greater than 30%.

[0014] (2) The present invention has a simple structure and good absorption rate. The absorption rate of the wave-absorbing shielding layer and the flexible packaging layer is more than 80%, and the absorption relative bandwidth exceeds 10 times the lowest frequency.

[0015] (3) The present invention uses multiple rings to be intertwined to form a structure with good tensile properties, thereby improving the ductility of the absorbing material and expanding the scope of use of the absorbing material. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural diagram of the wave absorbing structure of the second embodiment of the present invention.

[0017] Figure 2 It is a structural schematic diagram of the wave-absorbing shielding layer in the present invention.

[0018] Figure 3 1 is a reflection coefficient S11 curve diagram of Example 2 of the present invention and a comparative example.

[0019] Figure 4 2 is a transmission coefficient S21 curve diagram of Example 2 of the present invention and a comparative example.

[0020] Figure 5 1 is a graph showing the calculation results of the absorption rates of Example 2 of the present invention and the comparative example.

[0021] Among them: 1 flexible packaging layer; 2 wave absorbing shielding layer. DETAILED DESCRIPTION

[0022] The present invention will be further explained and illustrated below with reference to specific embodiments.

[0023] Example 1:

[0024] A flexible, light-transmitting, broadband absorbing structure comprises an absorbing shielding layer 2, the outer side of which is wrapped with a transparent flexible encapsulation layer 1. The absorbing shielding layer 2 is formed by interconnecting and nesting multiple rows of horizontal and vertical rings. A vertical ring is vertically arranged between two adjacent rows of horizontal rings, and adjacent horizontal rings are overlapped.

[0025] The wave-absorbing shielding layer 2 is made of a non-transparent flexible conductive material, carbon nanotubes / polydimethylsiloxane. The outer diameter of the ring in the wave-absorbing shielding layer 2 is 20 mm, the inner diameter is 16 mm, the thickness is 2 mm, the relative dielectric constant is 5, and the conductivity is 10 S / m.

[0026] The thickness of the flexible encapsulation layer 1 is 20 mm (exceeding the actual total thickness of the absorbing shielding layer by 2 mm), the relative dielectric constant is 2.75, and the loss tangent is 0.02.

[0027] Through calculation and measurement, it can be found that the transmittance of this flexible, transparent, broadband absorbing structure to visible light or infrared light is about 45%.

[0028] Example 2:

[0029] A flexible, light-transmitting, broadband absorbing structure comprises two absorbing shielding layers 2 distributed one above the other. The upper and lower absorbing shielding layers are wrapped with a transparent flexible encapsulation layer 1. The upper and lower absorbing shielding layers are both formed by interconnecting and nesting multiple rows of horizontal and vertical rings. A vertical ring is vertically arranged between two adjacent rows of horizontal rings to connect the adjacent rings into an absorbing shielding layer with a certain area. The horizontal rings in each row are overlapped with each other.

[0030] The upper and lower absorbing shielding layers are made of different non-transparent conductive materials: the upper absorbing shielding layer is made of carbon black / polydimethylsiloxane, and the lower absorbing shielding layer is made of graphene / polydimethylsiloxane. The upper absorbing shielding layer is formed by nesting circular rings with an outer diameter of 20mm, an inner diameter of 16mm, and a thickness of 2mm, with a relative dielectric constant of 5 and a conductivity of 10 S / m. The lower absorbing shielding layer is formed by nesting circular rings with an outer diameter of 10mm, an inner diameter of 8mm, and a thickness of 1mm, with a relative dielectric constant of 20 and a conductivity of 100 S / m.

[0031] The thickness of the flexible encapsulation layer is 28 mm (2 mm greater than the actual total thickness of the absorbing shielding layer), the relative dielectric constant is 2.75, and the loss tangent is 0.02.

[0032] The reflection coefficient S11 curve (such as Figure 3 ) and the transmission coefficient S21 curve (such as Figure 4 For comparison, a flexible, light-transmitting, broadband absorbing structure (Comparative Example 1) was simulated. This structure includes an absorbing shielding layer wrapped with a flexible encapsulation layer. The absorbing shielding layer is a single layer of unstructured, flexible conductive material. The absorbing shielding layer is made of a flexible conductive material, carbon nanotubes / polydimethylsiloxane, and is 26 mm thick, with a relative dielectric constant of 5 and a conductivity of 10 S / m. The structure is also simulated with a top and bottom flexible encapsulation layer, each 1 mm thick, with a relative dielectric constant of 2.75 and a loss tangent of 0.02.

[0033] like Figure 3-4 As shown in the figure, when using an unstructured, full-layer absorbing shielding layer, S11 < -2dB and S21 < -138dB at 5-50 GHz. After introducing the structured absorbing shielding layer described in this embodiment, the reflection coefficient S11 curve shows that S11 < -8dB. In the 5-25 GHz range, the reflection of the absorbing structure is significantly reduced compared to the reflection when using an unstructured, full-layer absorbing shielding layer. In the 25-50 GHz range, the overall reflection of the absorbing structure is very small. The transmission coefficient S21 curve shows that the absorbing structure still has a shielding effectiveness of more than 10dB, with S21 < -11dB.

[0034] According to the absorption rate (A) calculation formula A=1-|S11| 2 -|S21| 2 After the introduction of the structural absorbing shielding layer, the absorption rate is significantly improved. The absorption rate calculation results are as follows Figure 5 As shown, the absorbing structure described in this embodiment achieves broadband absorption within the 5-50 GHz frequency band. The absolute bandwidth where the absorption rate exceeds 80% exceeds 45 GHz, exceeding the absolute bandwidth of 32 GHz when using a full-layer absorbing shielding layer. This indicates that the introduction of the absorbing shielding layer described in this embodiment reduces reflections, shifts the absorption frequency toward lower frequencies, and increases the absorption bandwidth.

[0035] Through calculation and measurement, it can be found that the transmittance of this flexible, transparent, broadband absorbing structure to visible light or infrared light is about 35%.

Claims

1. A flexible, light-transmitting, broadband absorbing structure, characterized by: The wave-absorbing shielding layer comprises at least one wave-absorbing shielding layer, wherein the wave-absorbing shielding layer is made of an opaque flexible conductive material and the outer side of the wave-absorbing shielding layer is wrapped with a transparent flexible packaging layer; The wave-absorbing shielding layer is composed of an array of nested circular rings, and the light transmittance of the wave-absorbing shielding layer can be determined by adjusting the inner and outer diameters of the circular rings. The wave-absorbing shielding layer is formed by multiple rows of horizontal and vertical rings nested and connected with each other. A row of vertical rings is arranged between two adjacent rows of horizontal rings to connect the adjacent horizontal rings into a wave-absorbing shielding layer with a certain area. The horizontal rings in each row are placed overlapping with each other.

2. The flexible, light-transmitting, broadband absorbing structure according to claim 1, wherein: The flexible conductive material is carbon black / polydimethylsiloxane, carbon nanotube / polydimethylsiloxane, graphene / polydimethylsiloxane, poly(3,4-ethylenedioxythiophene) / polydimethylsiloxane or conductive rubber.

3. The flexible, light-transmitting, broadband absorbing structure according to claim 1, wherein: The thickness of the wave-absorbing shielding layer is 10-50 mm, the relative dielectric constant is 5-20, and the conductivity is set to 1-100 S / m.

4. The flexible, light-transmitting, broadband absorbing structure according to claim 1, wherein: The flexible packaging layer is made of transparent polydimethylsiloxane, vulcanized silicone rubber or polyethylene terephthalate.

5. The flexible, light-transmitting, broadband absorbing structure according to claim 1, wherein: The thickness of the flexible packaging layer exceeds that of the wave-absorbing shielding layer by 1-10 mm, the relative dielectric constant is 1-3, and the loss tangent value is less than 0.05.

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