CN115810919A - Ultra-wideband transparent electromagnetic wave absorber covering 3.7-43.5GHz - Google Patents
Ultra-wideband transparent electromagnetic wave absorber covering 3.7-43.5GHz Download PDFInfo
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- CN115810919A CN115810919A CN202211638639.3A CN202211638639A CN115810919A CN 115810919 A CN115810919 A CN 115810919A CN 202211638639 A CN202211638639 A CN 202211638639A CN 115810919 A CN115810919 A CN 115810919A
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Abstract
The invention discloses a broadband transparent electromagnetic wave absorber with a wave-absorbing frequency band covering 3.7-43.5GHz, which comprises four layers of transparent PET substrates distributed in parallel from top to bottom, wherein the four layers of transparent PET substrates sequentially comprise a first layer of PET substrate, a second layer of PET substrate, a third layer of PET substrate and a fourth layer of PET substrate from top to bottom, a plurality of ITO patch units which are periodically arranged are respectively etched on the top surfaces of the first layer of PET substrate, the second layer of PET substrate and the third layer of PET substrate, the fourth layer of PET substrate adopts a full-patch ITO-PET substrate with a total reflection characteristic, and an air layer exists between every two adjacent layers of PET substrates. The invention solves the problems of short working frequency range, poor light transmission and the like of the electromagnetic metamaterial at the present stage.
Description
Technical Field
The invention belongs to the technical field of electromagnetic materials, and particularly relates to an ultra wide band transparent electromagnetic wave absorber covering 3.7-43.5 GHz.
Background
Electromagnetic absorbers (EMA) are important Electromagnetic devices, and play an important role in the fields of Electromagnetic compatibility, electromagnetic stealth, information security and the like. With the rapid development of science and technology, various electronic components generate a large amount of electromagnetic radiation with different frequencies, and higher requirements are provided for indexes such as performance, size and angle stability of the suction filter. EMA is increasingly used because of its advantages such as high absorptivity and flexible design.
The prototype of EMA, originally developed in the salisburyscreen by american researchers Winfield Salisbury in 1952, consisted of a top metal film, a dielectric slab with a quarter of the operating wavelength thick, and a bottom metal reflector, was first used to reduce the radar cross-section of various warfare devices and reduce the risk of detection. Later, a variety of wave-absorbing materials have been developed to achieve the purposes of expanding bandwidth, hiding electromagnetism and better adapting to complex electromagnetic environments, and can be roughly classified into the following materials: the wave absorbing material comprises a plasma electromagnetic absorbing material, a nano wave absorbing material, a chiral electromagnetic absorbing material, a ferrite wave absorbing material, a polycrystalline iron fiber wave absorbing material, a conductive high polymer wave absorbing material and a metal micro powder composite wave absorbing material. But because they are difficult to reach most of the properties of the modern stealth materials, such as thinness, lightness, width and height, and have high manufacturing difficulty and high cost, the materials are difficult to be widely applied.
The Transparent Electromagnetic wave Absorber (Transparent Electromagnetic Absorber) is a novel wave Absorber proposed in recent years, and compared with the traditional Electromagnetic wave Absorber, the Transparent Electromagnetic wave Absorber has the advantages that the structure is made of Transparent materials, the Transparent Electromagnetic wave Absorber has obvious light transmission, and the limitation of lighttightness of the traditional wave absorbing device is broken. The transparent electromagnetic wave absorber expands the application scenes of electromagnetic wave absorbing materials, for example, the transparent wave absorber can be used in an aircraft cockpit with requirements on light transmission property to well realize electromagnetic stealth without influencing the light transmission property. With the appearance of the transparent wave absorber, various transparent electromagnetic wave absorbers with novel structures are proposed in succession, the functions and the performances of the transparent electromagnetic wave absorbers are also improved in succession, the electromagnetic wave absorbers capable of realizing double frequency points, multiple frequency points and wide frequency bands are gradually designed from the beginning of absorbing incident electromagnetic waves of single frequency points, the wave absorbers initially have the defects of polarization sensitivity and incident angle sensitivity of the incident electromagnetic waves, and the defects are slowly overcome along with the subsequent structural optimization design. The transparent electromagnetic wave absorber accords with the development advantages of modern stealth materials, namely thinness, lightness, height, width and transparency, so that the transparent electromagnetic wave absorber is widely researched by modern researchers.
In recent years, many transparent electromagnetic absorbers have been theoretically designed and experimentally manufactured. For a transparent absorber, both the topology and the substrate are made of transparent materials. In the transparent absorption design, indium Tin Oxide (ITO) is the most widely used transparent material due to its excellent material properties. The light-permeable ultra-wide band electromagnetic wave absorber based on the ITO film uses the ITO film to replace a traditional resistance film and uses the transparent medium substrate PET to replace a traditional medium plate, thereby realizing the visibility of the whole structure. The transparent electromagnetic wave absorber accords with the development advantages of modern stealth materials, namely thinness, lightness, height, width and transparency, so that the transparent electromagnetic wave absorber is widely researched by modern researchers and has important military and civil values.
Disclosure of Invention
The invention provides an ultra-wideband transparent electromagnetic wave absorber with a wave-absorbing frequency band covering 3.7-43.5GHz, which comprises four layers of Polyethylene terephthalate (PET) substrates, ITO patch units with different square resistance values etched on the PET substrates, and an intermediate air layer arranged between every two adjacent layers of PET substrates, wherein the intermediate air layer has a shielding effect on electromagnetic waves in a specific frequency band while realizing light transmission, and the problems of short working frequency band, poor light transmission and the like of the electromagnetic metamaterial in the prior art are solved.
The technical solution for realizing the invention is as follows: a broadband transparent electromagnetic wave absorber with wave absorbing frequency bands covering 3.7-43.5GHz comprises four layers of transparent PET substrates distributed in parallel from top to bottom, wherein the four layers of transparent PET substrates sequentially comprise a first layer of PET substrate, a second layer of PET substrate, a third layer of PET substrate and a fourth layer of PET substrate from top to bottom, a plurality of ITO patch units which are arranged periodically are respectively etched on the top surfaces of the first layer of PET substrate, the second layer of PET substrate and the third layer of PET substrate, the fourth layer of PET substrate is a full-patch ITO-PET substrate with total reflection characteristics, and an air layer is arranged between every two adjacent layers of PET substrates.
Compared with the prior art, the invention has the remarkable advantages that:
(1) The laminated structure comprises a square ring ITO (indium tin oxide) chip unit, a first layer PET (polyethylene terephthalate) substrate, an air layer, a square ring ITO chip unit, a second layer PET substrate, an air layer, a square ring ITO chip unit, a third layer PET substrate, an air layer, a full-chip ITO chip unit and a fourth layer PET substrate which are arranged from top to bottom to form a laminated structure, wherein the first layer PET substrate, the second layer PET substrate, the third layer PET substrate and the fourth layer PET substrate are made of PET with extremely high transparency, and the square ring ITO chip unit and the full-chip ITO chip unit are made of indium tin oxide materials with good light transmittance. Compared with the prior art, the electromagnetic wave absorber has the advantages that the wave absorbing bandwidth and wave absorbing rate are ensured, meanwhile, the good light transmission performance of the electromagnetic wave absorber is realized, and the application range is expanded.
(2) The square ring ITO patch unit adopted by the invention is a square ring array consisting of a plurality of transparent resistance films which are periodically arranged, and the square resistance of the resistance films is 100 omega/sq; the all-patch ITO patch units of the bottom plate are transparent films with the square resistance of 5 omega/sq, and can be regarded as metal conductors for reflecting electromagnetic waves due to certain resistivity. When electromagnetic waves are incident on the wave absorber provided by the invention, multiple reflections are formed between the dielectric layers and are finally matched with the impedance of a free space, a broadband wave absorbing effect is generated, high wave absorbing rate is realized in a working bandwidth, and the adopted resistance film has the characteristics of light weight and thin thickness, so that the thickness and weight of the wave absorber are reduced while the broadband wave absorbing effect and high wave absorbing rate are ensured, the wave absorber is more practical and is convenient to integrate with a microwave system.
(3) Because the conductive film and the bottom plate are made of indium tin oxide materials and soda-lime glass, compared with the prior art, the invention has the advantages of high mechanical hardness, good chemical stability and the like, can ensure the stability of performance for a long time, has longer service life, low price, convenient processing and manufacturing and extremely high cost performance.
Drawings
Fig. 1 is a schematic three-dimensional structure of the present invention.
Fig. 2 is a side view of the present invention.
FIG. 3 is a top view of the present invention, wherein (a) is a diagram of a first layer of PET substrate ITO patch unit, (b) is a diagram of a second layer of PET substrate ITO patch unit, and (c) is a diagram of a fourth layer of PET substrate ITO patch unit.
FIG. 4 is a wave absorption rate curve chart of the present invention under different polarizations.
FIG. 5 is a wave absorption rate curve diagram of the present invention under TE polarization and at different incident angles.
FIG. 6 is a graph of the absorption rate under TM polarization at different incident angles.
FIG. 7 is a plot of the surface current distribution of the present invention at 4.6 GHz.
FIG. 8 is a surface current distribution plot at 14GHz according to the invention.
FIG. 9 is a surface current distribution plot of the present invention at 37.7 GHz.
And p is the arrangement period of the ITO patch units on the first layer of PET substrate, the second layer of PET substrate and the third layer of PET substrate.
L is the side length of the square ITO patch unit on the third layer PET substrate.
and a is the inner side length of the square ring-shaped ITO patch unit on the first layer of PET substrate.
And b is the outer side length of the square ring-shaped ITO patch unit on the first layer of PET substrate.
And c is the square ring width of the square ring-shaped ITO patch unit on the second layer of PET substrate.
d is the outer side length of the square ring-shaped ITO patch unit on the second layer of PET substrate.
R S1 Is the square resistance of the ITO patch cells on the fourth layer of PET substrate.
R S2 Is the square resistance of the ITO patch units on the first layer of PET substrate, the second layer of PET substrate and the third layer of PET substrate.
t is the thickness of the four-layer PET substrate.
h 1 Is the spacing of the first layer of PET substrate and the second layer of PET substrate.
h 2 Is the spacing of the second and third PET substrates.
h 3 Is the spacing of the third and fourth PET substrates.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without inventive step, are within the scope of the present invention.
It should be noted that all directional indicators (such as up, down, left, right, front, back \8230;) in the embodiments of the present invention are only used to explain the relative positional relationship between the components, the motion situation, etc. in a specific posture (as shown in the attached drawings), and if the specific posture is changed, the directional indicator is changed accordingly.
In addition, descriptions such as "first", "second", etc. in the present invention are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the invention, "plurality" means at least two, e.g., two, three, etc., unless explicitly specified otherwise.
In the present invention, unless otherwise expressly specified or limited, the terms "connected," "secured," and the like are to be construed broadly, e.g., "secured" may be fixedly connected, releasably connected, or integral; "connected" may be mechanically or electrically connected. The specific meanings of the above terms in the present invention can be understood according to specific situations by those of ordinary skill in the art.
In addition, the technical solutions in the embodiments of the present invention may be combined with each other, but it must be based on the realization of those skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination of technical solutions should not be considered to exist, and is not within the scope of the claimed invention.
The following further introduces specific embodiments, technical difficulties and inventions of the present invention with reference to the design examples.
The invention relates to a broadband transparent electromagnetic wave absorber with a wave-absorbing frequency band covering 3.7-43.5GHz, which comprises four layers of transparent PET substrates distributed in parallel from top to bottom, wherein the four layers of transparent PET substrates sequentially comprise a first layer of PET substrate, a second layer of PET substrate, a third layer of PET substrate and a fourth layer of PET substrate from top to bottom, a plurality of ITO patch units which are periodically arranged are respectively etched on the top surfaces of the first layer of PET substrate, the second layer of PET substrate and the third layer of PET substrate, the fourth layer of PET substrate adopts a full-patch ITO-PET substrate with a total reflection characteristic, and an air layer is arranged between every two adjacent PET substrates. The ITO patch unit is a square ring array consisting of a plurality of transparent resistance films which are periodically arranged, and the specific design is shown below, wherein the square resistance of the resistance film is 100 omega/sq; the full-patch ITO patch unit of the bottom plate is a transparent film with the square resistance of 5 omega/sq. The four-layer transparent PET substrate has a relative dielectric constant of 3 and a magnetic permeability of 0.06.
ITO is a transparent surface resistance type conductive film, the main component of which is indium tin oxide, and the ITO is widely applied to displays of various electronic products in daily industry and is a common surface resistance type material with more perfect manufacturing process. The smaller the sheet resistance value of the ITO is, the better the conductivity of the ITO is, the closer the ITO is to metal, the more the energy of electromagnetic waves is reflected, and meanwhile, the thickness of the ITO is in inverse proportion to the sheet resistance and the light transmittance. Therefore, the novel flexible transparent metamaterial wave absorber is constructed by using the characteristic that the ITO is close to the conductive function of metal and replacing the ITO with the material of the traditional metal resonant structure, and the novel flexible transparent metamaterial wave absorber can additionally increase ohmic loss for incident electromagnetic waves besides the resonant loss of the structure, so that a stronger wave absorbing effect is realized. The PET substrate is made of high-light-transmission soda-lime glass, has good mechanical property and good bending resistance, is a flexible, transparent and chemically stable electric insulating material, has a dielectric constant epsilon =3, a magnetic conductivity mu =0.06 and a conductivity sigma = 0S/m, can well perform electromagnetic loss on incident electromagnetic waves when used as a middle dielectric layer of a wave absorber, and can be used as an ITO sputtering substrate.
As shown in figures 1 and 2, the invention discloses a broadband transparent electromagnetic wave absorber with wave-absorbing frequency band covering 3.7-43.5GHz, which comprises an ITO (indium tin oxide) patch unit, a first layer of PET (polyethylene terephthalate) substrate, a second layer of PET substrate, a third layer of PET substrate, a fourth layer of PET substrate and three air layers. The ITO paster units are printed on the upper surfaces of the first layer of PET substrate, the second layer of PET substrate and the third layer of PET substrate respectively through a magnetic sputtering technology, the square ring units are arranged periodically, and the fourth layer of PET substrate is completely covered by the full-paster ITO paster units with conductivity. As shown in fig. 2 and 3, the width of the PET substrate is p =5.5mm, the length of the PET substrate is L =5.4mm, the inner side length of the first layer ITO patch unit is a =3.2mm, the outer side length of the first layer ITO patch unit is b =4.5mm, the inner side length of the second layer ITO patch unit is c =1.4mm, the outer side length of the second layer ITO patch unit is d =5.2mm, and the resistance value of the fourth layer full-patch ITO patch unit is R S1 =5 Ω/sq, and resistance values of the rest ITO patch units are R S2 =100 Ω/sq, PET substrate thickness t =0.175mm, and spacing (i.e. air layer height) of first layer PET substrate and second layer PET substrate h 1 =2.5mm, and the distance between the second PET substrate and the third PET substrate (namely the height of an air layer) is h 2 =2.5mm, third layer PET baseThe distance between the bottom and fourth PET substrate (i.e. the air layer height) is h 3 =3mm。
The four-layer PET substrate adopts PET with the relative dielectric constant of 3, the loss tangent of 0.06 and the thickness of 0.175 mm. The interlayer air layer is used for realizing interlayer coupling of electromagnetic waves, so that impedance in the wave absorber is matched with impedance in a free space, and a better wave absorbing effect is realized.
With reference to fig. 4, the periodic structure in fig. 1 is utilized to obtain a wave absorption rate curve of the transparent absorber under different polarizations of 3.7 to 43.5GHz through simulation of the CST stub Suite of the commercial electromagnetic simulation software, wherein the abscissa represents frequency, and the ordinate represents absorption rate of electromagnetic wave energy, and it can be seen that the wave absorption rate in 3.7 to 43.5GHz is greater than 90%. Fig. 5 is a wave absorption rate curve of the present invention under TE polarization at different incident angles, where the abscissa is frequency and the ordinate is absorption rate of electromagnetic energy. FIG. 6 is a wave absorption rate curve of the present invention under TM polarization and at different incident angles.
In order to better understand the absorption mechanism of the broadband wave absorber provided by the invention, the surface current distributions of the layer structures from top to bottom at three frequency points of 4.6GHz, 14GHz and 37.7GHz, where the absorption rate is the largest, are shown in fig. 7 to 9, respectively. Referring to fig. 7, it is seen that at 4.6GHz, the current distribution of each layer of the EMA is strong, the current of the bottom layer is distributed from bottom to top, and the current of the other three layers are distributed from top to bottom. Therefore, magnetic resonance is formed between the bottom layer and other layers, the current directions between the other layers are the same, the current distribution forms a closed loop, and electric resonance is formed. Similarly, referring to fig. 8, the current distribution of the lower two-layer structure is from bottom to top, while the current distribution of the other two layers is opposite, referring to fig. 9, the current distribution of the bottom and top layer structures is from bottom to top, while the current distribution of the other two layers is opposite. At this time, one electric resonance and two magnetic resonances are generated inside the EMA. Therefore, when the current distribution on the surface of the ITO patch unit is large, the ohmic loss of the corresponding ITO patch unit is also increased, thereby converting more electromagnetic energy into heat. In addition, the bandwidth of the EMA can be greatly expanded due to the existence of the triple resonance, and broadband is realized.
Simulation results show that the absolute working bandwidth of the invention is more than 3985GHz with relative bandwidth of 169.03%, wave absorbing rate of more than 90% and thickness of 0.68 lambda 0 (wherein. Lambda 0 The wavelength corresponding to the wave-absorbing central frequency point). In addition, the wave absorber provided by the invention has the characteristics of polarization insensitivity and angle stability, and compared with the prior art, the wave absorber has higher light transmission and smaller weight while ensuring the wave absorbing rate and wave absorbing bandwidth.
The above-mentioned embodiments, objects, technical solutions and advantages of the present application are further described in detail, it should be understood that the above-mentioned embodiments are only examples of the present application, and are not intended to limit the scope of the present application, and any modifications, equivalent substitutions, improvements and the like made on the basis of the technical solutions of the present application should be included in the scope of the present application.
Claims (5)
1. A broadband transparent electromagnetic wave absorber with wave-absorbing frequency band covering 3.7-43.5GHz is characterized in that: including four layers of transparent PET basement of top-down parallel distribution, four layers of transparent PET basement top-down is first layer PET basement in proper order, second floor PET basement, third layer PET basement and fourth layer PET basement, at first layer PET basement, the ITO paster unit that a plurality of cycles were arranged has been etched respectively to the top surface of second layer PET basement and third layer PET basement, fourth layer PET basement adopts the full paster ITO-PET basement that has the total reflection characteristic, there is the air bed between the adjacent two-layer PET basement.
2. The broadband transparent electromagnetic absorber of claim 1, wherein the absorbing frequency band covers 3.7-43.5GHz, and the broadband transparent electromagnetic absorber is characterized in that: the ITO patch unit is formed by etching ITO with the sheet resistance of 100 omega/sq.
3. The broadband transparent electromagnetic absorber of claim 2, wherein the absorbing frequency band covers 3.7-43.5GHz, and the broadband transparent electromagnetic absorber is characterized in that: the ITO-PET substrate with the total reflection characteristic is formed by etching ITO with the sheet resistance of 5 omega/sq on PET.
4. The broadband transparent electromagnetic absorber of claim 3, wherein the absorbing frequency band covers 3.7-43.5GHz, and the broadband transparent electromagnetic absorber is characterized in that: the four-layer transparent PET substrate has the relative dielectric constant of 3 and the magnetic permeability of 0.06.
5. The broadband transparent electromagnetic absorber according to claim 4, wherein the absorbing frequency band of the absorber covers 3.7-43.5GHz, and the broadband transparent electromagnetic absorber is characterized in that: the width of a PET substrate is p =5.5mm, the length of the PET substrate is L =5.4mm, the inner side length of a first layer ITO patch unit is a =3.2mm, the outer side length of the first layer ITO patch unit is b =4.5mm, the inner side length of a second layer ITO patch unit is c =1.4mm, the outer side length of the second layer ITO patch unit is d =5.2mm, and the resistance value of a fourth layer full-patch ITO patch unit is R S1 =5 Ω/sq, and resistance values of the rest ITO patch units are R S2 =100 Ω/sq, PET substrate thickness t =0.175mm, air layer height h of first layer PET substrate and second layer PET substrate 1 =2.5mm, the height of the air layer of the second and third PET substrate is h 2 =2.5mm, and the air layer height of the third and fourth PET substrates is h 3 =3mm。
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| CN202211638639.3A CN115810919A (en) | 2022-12-20 | 2022-12-20 | Ultra-wideband transparent electromagnetic wave absorber covering 3.7-43.5GHz |
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| CN202211638639.3A CN115810919A (en) | 2022-12-20 | 2022-12-20 | Ultra-wideband transparent electromagnetic wave absorber covering 3.7-43.5GHz |
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