Light transparent flexible electromagnetic wave-absorbing metamaterial

Abstract

The invention provides an optical transparent flexible electromagnetic wave-absorbing metamaterial, and relates to the technical field of wave-absorbing materials, the electromagnetic wave-absorbing metamaterial comprises a plurality of wave-absorbing units arranged periodically, and the wave-absorbing units are made of optical transparent materials; each wave absorbing unit comprises a dielectric compensation layer, a first resonance layer, a first dielectric layer, a second resonance layer, a second dielectric layer and a reflecting layer which are sequentially arranged from top to bottom; the dielectric compensation layer is used for expanding an absorption frequency band and improving the stability of an incident angle; the first resonance layer is used for adjusting a first resonance frequency point of a reflectivity curve; the second resonance layer is used for adjusting a second resonance frequency point of the reflectivity curve; the first dielectric layer and the second dielectric layer are used for consuming electromagnetic energy; and the reflecting layer is used for reflecting redundant electromagnetic energy back to the electromagnetic wave-absorbing metamaterial for loss again. The light-transparent flexible electromagnetic wave-absorbing metamaterial provided by the invention has the advantages of flexibility, high light transmittance, good broadband wave-absorbing performance and oblique incidence angle stability.

Description

Technical Field

[0001] The invention belongs to the technical field of wave-absorbing materials, and in particular relates to a light-transparent flexible electromagnetic wave-absorbing metamaterial. Background Art

[0002] Electromagnetic metamaterial absorbers are man-made structures with sub-wavelength scales, which can flexibly adjust the absorption frequency band and amplitude by changing the shape, size and arrangement of the pattern structure. However, the existing electromagnetic metamaterial absorbers use a hard opaque structure of "metal pattern-dielectric substrate-continuous metal", which cannot meet the specific application scenarios such as aircraft cockpit glass, conference room windows, and display screens, which require absorbers with high transmittance in the visible light band.

[0003] Therefore, there is an urgent need for an optically transparent, flexible, electromagnetic absorbing metamaterial to meet the requirements of specific scenarios for high optical transparency and wide absorbing bandwidth of absorbing materials. Summary of the invention

[0004] In response to one or more problems existing in the prior art, the present invention provides an optically transparent, flexible, electromagnetic absorbing metamaterial. The optically transparent, flexible, electromagnetic absorbing metamaterial provided by the present invention has flexibility, high light transmittance, good broadband absorbing performance and stability at oblique incident angles, and can meet the requirements of specific scenarios for absorbing materials with high optical transparency, wide absorbing frequency band and high stability at oblique incident angles.

[0005] In a first aspect, the present invention provides an optically transparent flexible electromagnetic absorbing metamaterial, wherein the electromagnetic absorbing metamaterial comprises a plurality of absorbing units arranged periodically, wherein the absorbing units are made of optically transparent materials; each absorbing unit comprises a dielectric compensation layer, a first resonance layer, a first dielectric layer, a second resonance layer, a second dielectric layer and a reflection layer arranged in sequence from top to bottom;

[0006] The dielectric compensation layer is used to expand the absorption band and improve the stability of the incident angle;

[0007] The first resonant layer is used to adjust a first resonant frequency point of a reflectivity curve;

[0008] The second resonance layer is used to adjust a second resonance frequency point of a reflectivity curve;

[0009] The first dielectric layer and the second dielectric layer are used for dissipating electromagnetic energy;

[0010] The reflective layer is used to reflect the redundant electromagnetic energy back to the electromagnetic absorbing metamaterial for further loss.

[0011] In a possible design, the dielectric compensation layer, the first dielectric layer and the second dielectric layer are made of polyvinyl chloride;

[0012] The first resonance layer is an open square high square resistance transparent conductive film with openings on all four sides;

[0013] The second resonance layer is a square high-square-resistance transparent conductive film; and / or

[0014] The reflective layer is a low-resistance transparent conductive film.

[0015] In a possible design, the thickness of the dielectric compensation layer and the first dielectric layer is greater than the thickness of the second dielectric layer; and / or

[0016] The first resonance layer and the second resonance layer have the same thickness.

[0017] In a possible design, the thickness of the dielectric compensation layer and the first dielectric layer is 2.6-3.4 mm;

[0018] The thickness of the second dielectric layer is 1.7 to 2.3 mm; and / or

[0019] The thickness of the first resonance layer and the second resonance layer is 0.16-0.18 mm.

[0020] In a possible design, the side length of the open square high-resistance transparent conductive film is smaller than the side length of the square high-resistance transparent conductive film.

[0021] In a possible design, the side length of the open square high-square-resistance transparent conductive film is 10 to 11 mm;

[0022] The length of the opening is 1.5 to 2.5 mm, and the width is 0.9 to 1.1 mm; and / or

[0023] The side length of the square high-square-resistance transparent conductive film is 13-15 mm.

[0024] In a possible design, the sheet resistance of the open square high-sheet-resistance transparent conductive film is lower than the sheet resistance of the square high-sheet-resistance transparent conductive film.

[0025] In a possible design, the sheet resistance of the open square high-sheet-resistance transparent conductive film is 60-80Ω / sq;

[0026] The square high-resistance transparent conductive film has a square resistance of 80 to 100 Ω / sq; and / or

[0027] The sheet resistance of the low-sheet-resistance transparent conductive film is 3-8Ω / sq.

[0028] In a possible design, the transparent conductive film is a polyethylene terephthalate film with indium tin oxide sputtered on the surface.

[0029] In a possible design, the arrangement period of the absorbing units is 15 mm.

[0030] Compared with the prior art, the present invention has at least the following beneficial effects:

[0031] The present invention uses optically transparent flexible materials to design a basic unit (wave absorbing unit) to ensure that the wave absorbing unit has flexibility and high light transmittance; expands the absorption band and improves the stability of the incident angle by loading a dielectric compensation layer; realizes a specific resonance frequency by optimizing the structural geometric parameters of the first resonance layer and the second resonance layer; uses the first dielectric layer and the second dielectric layer to dissipate the incident electromagnetic energy; reflects the redundant electromagnetic energy back to the electromagnetic wave absorbing metamaterial through the reflection layer to dissipate it again, thereby improving the wave absorbing effect of the wave absorbing metamaterial, and realizing that the wave absorbing metamaterial has a good wave absorbing effect in a wider frequency band.

[0032] The optically transparent flexible electromagnetic absorbing metamaterial provided by the present invention adopts optically transparent flexible materials to achieve high transmittance and flexibility, realizes broadband electromagnetic energy absorption in the radar band based on broadband impedance matching effect and energy loss effect, and further expands the working frequency band and improves the oblique incidence angle stability by loading a dielectric compensation layer, so that the absorbing metamaterial has flexibility, high transmittance, good broadband absorbing performance and oblique incidence angle stability, solves the problems that similar products at this stage are difficult to take into account high optical transmittance, wide absorption band and high oblique incidence angle stability and difficult to conform, and can meet the use requirements of high optical transparency and wide absorbing band of absorbing materials in specific scenarios such as aircraft cockpit glass, conference room windows, and display screens. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 This is a schematic diagram of the structure of an absorbing unit of an optically transparent flexible electromagnetic absorbing metamaterial provided by an embodiment of the present invention;

[0035] Figure 2 It is a schematic structural diagram of the first resonant layer in the wave absorbing unit of the optically transparent flexible electromagnetic wave absorbing metamaterial provided by one embodiment of the present invention;

[0036] Figure 3 It is a schematic structural diagram of the second resonance layer in the wave absorbing unit of the optically transparent flexible electromagnetic wave absorbing metamaterial provided in one embodiment of the present invention;

[0037] Figure 4 is an electromagnetic wave absorption characteristic curve of an optically transparent flexible electromagnetic wave absorbing metamaterial provided by an embodiment of the present invention;

[0038] Figure 5 This is a curve of the oblique incidence angle stability of the return loss of the optically transparent flexible electromagnetic absorbing metamaterial in the TE polarization mode provided by an embodiment of the present invention.

[0039] Figure 6 This is a curve of the oblique incidence angle stability of the return loss of the optically transparent flexible electromagnetic absorbing metamaterial in the TM polarization mode provided by an embodiment of the present invention.

[0040] Reference numerals:

[0041] 1-dielectric compensation layer; 2-first resonance layer; 3-first dielectric layer; 4-second resonance layer; 5-second dielectric layer; 6-reflection layer; L1-side length of the open square high-resistance transparent conductive film; L2-length of the opening; L3-side length of the square high-resistance transparent conductive film; W-width of the opening; P-arrangement period of the absorbing unit. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are 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 work are within the scope of protection of the present invention.

[0043] like Figure 1-3 As shown, the present invention provides an optically transparent flexible electromagnetic absorbing metamaterial in a first aspect, wherein the electromagnetic absorbing metamaterial comprises a plurality of absorbing units arranged periodically, wherein the absorbing units are made of optically transparent materials; each absorbing unit comprises a dielectric compensation layer 11, a first resonance layer 2, a first dielectric layer 3, a second resonance layer 4, a second dielectric layer 5 and a reflective layer 6 which are sequentially arranged from top to bottom;

[0044] The dielectric compensation layer 1 is used to expand the absorption band and improve the stability of the incident angle;

[0045] The first resonant layer 2 is used to adjust the first resonant frequency point of the reflectivity curve;

[0046] The second resonant layer 4 is used to adjust the second resonant frequency point of the reflectivity curve;

[0047] The first dielectric layer 3 and the second dielectric layer 5 are used for dissipating electromagnetic energy;

[0048] The reflective layer 6 is used to reflect the redundant electromagnetic energy back to the electromagnetic absorbing metamaterial for further loss.

[0049] The present invention uses optically transparent flexible materials to design a basic unit (wave absorbing unit) to ensure that the wave absorbing unit has flexibility and high light transmittance; expands the absorption band and improves the stability of the incident angle by loading a dielectric compensation layer; realizes a specific resonance frequency by optimizing the structural geometric parameters of the first resonance layer and the second resonance layer; uses the first dielectric layer and the second dielectric layer to dissipate the incident electromagnetic energy; reflects the redundant electromagnetic energy back to the electromagnetic wave absorbing metamaterial through the reflection layer to dissipate it again, thereby improving the wave absorbing effect of the wave absorbing metamaterial, and realizing that the wave absorbing metamaterial has a good wave absorbing effect in a wider frequency band.

[0050] The optically transparent flexible electromagnetic absorbing metamaterial provided by the present invention adopts optically transparent flexible materials to achieve high transmittance and flexibility, realizes broadband electromagnetic energy absorption in the radar band based on broadband impedance matching effect and energy loss effect, and further expands the working frequency band and improves the oblique incidence angle stability by loading a dielectric compensation layer, so that the absorbing metamaterial has flexibility, high transmittance, good broadband absorbing performance and oblique incidence angle stability, solves the problems that similar products at this stage are difficult to take into account high optical transmittance, wide absorption band and high oblique incidence angle stability and difficult to conform, and can meet the use requirements of high optical transparency and wide absorbing band of absorbing materials in specific scenarios such as aircraft cockpit glass, conference room windows, and display screens.

[0051] The optically transparent flexible electromagnetic absorbing metamaterial provided by the present invention has a return loss of less than -10dB in the operating frequency band of 4.04 to 26.51GHz. In the oblique incidence angle range of 0 to 40° in the dual-polarization state, the operating frequency band with a return loss lower than -10dB is less affected.

[0052] It should be noted that each layer is bonded with an optically transparent adhesive (OCA) to ensure light transmittance.

[0053] In some embodiments, the dielectric compensation layer 1, the first dielectric layer 3 and the second dielectric layer 5 are made of polyvinyl chloride, and the dielectric constants are all 2.4-j0.06.

[0054] In some embodiments, the first resonance layer 2 is an open square high-resistance transparent conductive film with openings on all four sides.

[0055] In some embodiments, the second resonance layer 4 is a square high-resistance transparent conductive film.

[0056] The present invention processes the transparent conductive film into an opening square or square pattern of a specific size through a laser etching process to meet the requirements of the first resonance layer and the second resonance layer.

[0057] In some embodiments, the reflective layer 6 is a low-resistance transparent conductive film.

[0058] In some embodiments, the thickness of the dielectric compensation layer 1 and the first dielectric layer 3 is greater than the thickness of the second dielectric layer 5 .

[0059] In some embodiments, the first resonance layer 2 and the second resonance layer 4 have the same thickness.

[0060] In some embodiments, the thickness of the dielectric compensation layer 1 and the first dielectric layer 3 is 2.6-3.4 mm.

[0061] In this embodiment, by optimizing the thickness of the dielectric compensation layer, not only the wave absorption rate of the wave absorbing unit can be improved, but also the bandwidth can be widened and the incident angle of the electromagnetic wave can be improved, so that the electromagnetic wave incident angle has a good wave absorption effect within the range of 0 to 40 degrees.

[0062] In some embodiments, the thickness of the second dielectric layer 5 is 1.7-2.3 mm.

[0063] In some embodiments, the thickness of the first resonance layer 2 and the second resonance layer 4 is 0.16-0.18 mm.

[0064] In some embodiments, the side length L1 of the open square high-resistance transparent conductive film is smaller than the side length L3 of the square high-resistance transparent conductive film.

[0065] In some embodiments, the side length L1 of the open square high-resistance transparent conductive film is 10-11 mm.

[0066] In some embodiments, the length L2 of the opening is 1.5-2.5 mm, and the width W is 0.9-1.1 mm.

[0067] In some embodiments, the side length L3 of the square high-square-resistance transparent conductive film is 13-15 mm.

[0068] In some embodiments, the sheet resistance of the open square high-sheet-resistance transparent conductive film is lower than the sheet resistance of the square high-sheet-resistance transparent conductive film.

[0069] In some embodiments, the sheet resistance of the open square high-sheet-resistance transparent conductive film is 60-80Ω / sq.

[0070] In some embodiments, the square high-resistance transparent conductive film has a sheet resistance of 80 to 100 Ω / sq.

[0071] The present invention can ensure a high light transmittance in the visible light band by selecting the first resonance layer and the second resonance layer of suitable square resistance (square resistance), so that the applicable scope of the wave absorbing unit can be increased, for example, it can be applied to special-shaped glass, solar panels and transparent RF identification systems. The inventor found that when the square resistance of the first resonance layer (open square high square resistance transparent conductive film) is 70Ω / sq, the amplitude (return loss) of the first resonance frequency generated by the reflection curve is the largest, and when the square resistance of the second resonance layer (square high square resistance transparent conductive film) is 90Ω / sq, the amplitude (return loss) of the second resonance frequency generated by the reflection curve is the largest. When the square resistance of the first resonance layer (open square high square resistance transparent conductive film) and the second resonance layer (square high square resistance transparent conductive film) is controlled within the above range, it can ensure that the wave absorbing unit has a high light transmittance while having good wave absorbing performance.

[0072] In some embodiments, the sheet resistance of the low-sheet-resistance transparent conductive film is 3-8Ω / sq.

[0073] The reflective layer of the present invention selects the low-square-resistance transparent conductive film in the above range to reflect the redundant electromagnetic energy back to the absorber for further loss.

[0074] In some embodiments, the transparent conductive film is a polyethylene terephthalate film with indium tin oxide sputtered on the surface.

[0075] The present invention utilizes indium tin oxide with good light transmittance and conductivity to sputter on a polyethylene terephthalate film with high light transmittance and low refractive index to obtain a transparent conductive film, which ensures its light transmittance while making it resistive. The sputtering thickness of indium tin oxide is inversely proportional to the sheet resistance, and a transparent conductive film with different sheet resistances can be obtained by controlling the sputtering thickness of indium tin oxide.

[0076] In some embodiments, the arrangement period of the absorbing units is 15 mm.

[0077] In a specific embodiment of the present invention, Figure 1-3, an optically transparent flexible electromagnetic absorbing metamaterial, comprising a plurality of absorbing units arranged in a periodic manner, wherein the absorbing units are made of optically transparent materials; each absorbing unit comprises a dielectric compensation layer 1, a first resonance layer 2, a first dielectric layer 3, a second resonance layer 4, a second dielectric layer 5 and a reflection layer 6 arranged in sequence from top to bottom; the dielectric compensation layer 1, the first dielectric layer 3 and the second dielectric layer 5 are made of polyvinyl chloride; the thickness of the dielectric compensation layer 1 and the first dielectric layer 3 is 3 mm; the thickness of the second dielectric layer 5 is 2 mm; the first resonance layer 2 is an open square high-square-resistance transparent conductive film (open square high-square-resistance transparent conductive film) with openings on all four sides The side length L1 of the conductive film is 10.5 mm, the length L2 of the opening is 2 mm, the width W is 1 mm, the thickness is 0.175 mm; the square resistance is 70 Ω / sq); the second resonant layer 4 is a square high-square-resistance transparent conductive film (the side length L3 of the square high-square-resistance transparent conductive film is 14 mm, the thickness is 0.175 mm; the square resistance is 90 Ω / sq); the reflective layer 6 is a low-square-resistance transparent conductive film (the thickness is 0.175 mm, and the square resistance is 5 Ω / sq); the transparent conductive film is a polyethylene terephthalate film with indium tin oxide sputtered on the surface; the arrangement period P of the absorbing unit is 15 mm.

[0078] In order to verify that the absorbing unit has a high electromagnetic wave absorption rate and oblique incident angle stability, the inventors used an absorbing metamaterial with a size of 300 mm long × 300 mm wide × 8.525 mm thick as a test sample, and used the "arch frame + broadband double horn antenna" test system to test the electromagnetic wave absorption characteristics of the test sample (such as Figure 4 ) and oblique incidence angle stability (e.g. Figure 5-6 ) was verified.

[0079] Depend on Figure 4 It can be seen that the test sample has a return loss below -10dB in the operating frequency band of 4.04 to 26.51GHz. 11 is the return loss (reflectivity), S 21 is the transmission coefficient, and the sum of their squares is equal to 1.

[0080] Depend on Figure 5-6 It can be seen that, in the TE and TM polarization modes, the absorbing unit of the test sample is less affected when the oblique incident angle is in the range of 0 to 40° and the return loss is lower than -10dB in the working frequency band, that is, the test sample has good incident angle stability.

[0081] In the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "first", "second", etc. are used only for descriptive purposes and cannot be understood as indicating or implying relative importance; unless otherwise specified or explained, the term "multiple groups" refers to two or more groups; the terms "connected", "fixed", etc. should be understood in a broad sense, for example, "connected" can be a fixed connection, a detachable connection, an integral connection, or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0082] In the description of this specification, it should be understood that the directional words such as "upper" and "lower" described in the embodiments of the present invention are described at the angles shown in the drawings and should not be understood as limiting the embodiments of the present invention. In addition, in the context, it should also be understood that when it is mentioned that an element is connected to another element "upper" or "lower", it can not only be directly connected to another element "upper" or "lower", but also indirectly connected to another element "upper" or "lower" through an intermediate element.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A light-transparent flexible electromagnetic absorbing metamaterial, characterized in that: The electromagnetic absorbing metamaterial comprises a plurality of absorbing units arranged in a periodic manner, wherein the absorbing units are made of optically transparent materials; each absorbing unit comprises a dielectric compensation layer, a first resonance layer, a first dielectric layer, a second resonance layer, a second dielectric layer and a reflection layer arranged in sequence from top to bottom; The dielectric compensation layer is used to expand the absorption band and improve the stability of the incident angle; The first resonant layer is used to adjust a first resonant frequency point of a reflectivity curve; The second resonance layer is used to adjust a second resonance frequency point of a reflectivity curve; The first dielectric layer and the second dielectric layer are used for dissipating electromagnetic energy; The reflective layer is used to reflect the redundant electromagnetic energy back to the electromagnetic absorbing metamaterial for further loss.

2. The electromagnetic absorbing metamaterial according to claim 1, characterized in that: The dielectric compensation layer, the first dielectric layer and the second dielectric layer are made of polyvinyl chloride; The first resonance layer is an open square high square resistance transparent conductive film with openings on all four sides; The second resonance layer is a square high-square-resistance transparent conductive film; and / or The reflective layer is a low-resistance transparent conductive film.

3. The electromagnetic absorbing metamaterial according to claim 2, characterized in that: The thickness of the dielectric compensation layer and the first dielectric layer is greater than the thickness of the second dielectric layer; and / or The first resonance layer and the second resonance layer have the same thickness.

4. The electromagnetic absorbing metamaterial according to claim 3, characterized in that: The thickness of the dielectric compensation layer and the first dielectric layer is 2.6-3.4 mm; The thickness of the second dielectric layer is 1.7 to 2.3 mm; and / or The thickness of the first resonance layer and the second resonance layer is 0.16-0.18 mm.

5. The electromagnetic absorbing metamaterial according to claim 2, characterized in that: The side length of the open square high-resistance transparent conductive film is smaller than the side length of the square high-resistance transparent conductive film.

6. The electromagnetic absorbing metamaterial according to claim 5, characterized in that: The side length of the open square high-square-resistance transparent conductive film is 10-11 mm; The length of the opening is 1.5 to 2.5 mm, and the width is 0.9 to 1.1 mm; and / or The side length of the square high-square-resistance transparent conductive film is 13-15 mm.

7. The electromagnetic absorbing metamaterial according to claim 2, characterized in that: The sheet resistance of the open square high-sheet-resistance transparent conductive film is lower than the sheet resistance of the square high-sheet-resistance transparent conductive film.

8. The electromagnetic absorbing metamaterial according to claim 5, characterized in that: The square resistance of the open square high-square-resistance transparent conductive film is 60-80Ω / sq; The square high-resistance transparent conductive film has a square resistance of 80 to 100 Ω / sq; and / or The sheet resistance of the low-sheet-resistance transparent conductive film is 3-8Ω / sq.

9. The electromagnetic absorbing metamaterial according to claim 2, characterized in that: The transparent conductive film is a polyethylene terephthalate film with indium tin oxide sputtered on the surface.

10. The electromagnetic absorbing metamaterial according to claim 1, characterized in that: The arrangement period of the wave absorbing units is 15 mm.

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