A transparent absorbing and transparent wave integrated electromagnetic material unit based on complementary structure

Abstract

The application discloses a transparent and absorbing wave integrated electromagnetic material unit based on a complementary structure, which comprises top, middle and bottom dielectric layers which are arranged in parallel and at intervals from top to bottom, and the same transparent ITO film arranged in a circular ring is arranged on the upper surface of the top dielectric layer and the upper surface of the bottom dielectric layer, the transparent ITO film arranged in a circular ring is arranged on the upper surface of the middle dielectric layer, and air layers are arranged between the adjacent two dielectric layers. The application has the advantages of high mechanical hardness, good chemical stability and the like, can ensure the stability of performance for a long time, has a longer service life, is low in price, convenient in processing and manufacturing, and is extremely high in cost performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of electromagnetic materials, and particularly relates to a transparent and wave-absorbing integrated electromagnetic material unit based on a complementary structure. BACKGROUND

[0002] With the increasing complexity of the contemporary electromagnetic environment, the technical demand for efficient regulation of space electromagnetic waves is constantly increasing, which has shown great application potential in military and civilian fields. At present, the main technology for regulating space electromagnetic waves is artificial electromagnetic structure (different from the antenna relied on by the communication system). However, with the increasing demand for functions, the development of artificial electromagnetic structure technology has entered a new stage, and the traditional optical non-transparency, fixed function and complex structure design are far from meeting the needs of the contemporary electromagnetic environment. Intelligent and efficient theory and design research have become the inevitable trend of future development in this field. Electronic countermeasure mode has become an important combat means in modern war. In order to protect our equipment in electronic warfare, current researches are mostly concentrated in the field of stealth, and the research goal is mostly focused on improving the stealth performance and adjustable characteristics. However, pure stealth or adjustable characteristic devices and materials often do not have optical transparency in real electric field environment, so that the advanced functional design cannot be fully utilized.

[0003] As a kind of spatial filter, frequency selective surface (FSS) can transmit or reflect electromagnetic waves in a specific frequency band, and its spatial filtering characteristics are determined by multiple parameters such as structure shape and size, medium thickness and dielectric constant, and incident electromagnetic wave angle and polarization state. Due to the good regulation ability of electromagnetic waves and the large degree of design freedom, FSS has been widely used in radar antenna cover, electromagnetic wave absorber, electromagnetic polarizer and electromagnetic compatibility and many other fields. The research on FSS is developing towards the direction of multi-field intersection, involving physics, engineering and materials and other disciplines.

[0004] Since 1960s, researchers have begun to study the electrical properties of FSS and its periodic structure. The periodic structure of FSS refers to the infinite array formed by the same basic unit structure arranged in a certain way along one or two-dimensional direction. The metal structure in FSS is usually loaded on a single layer of dielectric substrate material, and in some structures, there can be multiple layers of metal structure and multiple layers of dielectric material to form a three-dimensional structure. Unlike the function of general structure type electromagnetic elements, FSS can control and select the frequency, polarization and incident angle of the incident electromagnetic wave. Based on the frequency filtering characteristics of FSS, in recent years, FSS technology has been widely used in military and civilian electromagnetic equipment. In the military field, FSS can be used for stealth protection of aircraft and communication radar antenna covers and protective screens, functional regulation of reconfigurable antennas, etc. In civil aspects, FSS can be used as wave-absorbing material and shielding material for information security protection, electromagnetic shielding, anti-interference and microwave darkroom of electromagnetic equipment, electromagnetic shielding of satellite communication, etc.

[0005] Electromagnetic absorber (EMA) is an important electromagnetic protection device, which plays a very important role in electromagnetic compatibility, electromagnetic stealth, information security and other fields. With the rapid development of science and technology, a large number of electronic components of different frequencies produce electromagnetic radiation, which puts forward higher requirements on the performance, size, angle stability and other indicators of the absorber. EMA has been widely used due to its high absorption rate, flexible design and other advantages.

[0006] The prototype of EMA was first proposed by Winfield Salisbury, an American researcher, in 1952, and is derived from Salisbury Screen, which is composed of a top metal film, a dielectric plate with a working wavelength of one-fourth thickness, and a bottom metal reflection plate. It was first used to reduce the radar scattering cross section of various war equipment and reduce the risk of being detected. Later, many kinds of wave-absorbing materials were developed to achieve the purpose of expanding the bandwidth, electromagnetic stealth and better adapting to complex electromagnetic environment. They can be roughly classified into the following materials: plasmonic electromagnetic absorbing material, nano wave-absorbing material, chiral electromagnetic wave-absorbing material, ferrite wave-absorbing material, polycrystalline iron fiber wave-absorbing material, conductive high polymer wave-absorbing material and metal micro-powder composite wave-absorbing material. However, due to their difficulty in achieving most of the performance of modern stealth materials "thin, light, wide and high", as well as the difficulty in production and high cost, they are difficult to be widely used.

[0007] Transparent electromagnetic absorber is a new type of absorber proposed in recent years. Compared with traditional electromagnetic absorber, its structure is composed of transparent materials, and it has obvious light transmission, which breaks the limitation of traditional absorber that it is not transparent. The emergence of transparent electromagnetic absorber expands the application scenarios of electromagnetic wave absorbing materials. For example, transparent absorber can be used in aircraft cockpit which requires light transmission, and electromagnetic stealth can be realized without affecting light transmission. With the emergence of transparent absorber, various new structures of transparent electromagnetic absorber have been proposed, and their functions and performance have been improved. Initially, it can absorb single frequency point of incident electromagnetic wave, and then gradually design electromagnetic absorber that can realize double frequency point, multi-frequency point and wide frequency band. The initial electromagnetic absorber has the defects of polarization sensitivity and incident angle sensitivity of incident electromagnetic wave, but after the structure optimization design, these defects are gradually overcome. Transparent electromagnetic absorber meets the development advantages of modern stealth materials, such as thin, light, high, wide and transparent, so it is widely studied by modern researchers.

[0008] In recent years, many transparent electromagnetic absorbers have been theoretically designed and experimentally manufactured. For transparent absorbers, the topological structure and substrate are made of transparent materials. In the design of transparent absorption, indium tin oxide (ITO) is the most widely used transparent material due to its excellent material performance. The light-transmitting ultra-wideband electromagnetic absorber based on ITO film uses ITO film to replace the traditional resistive film and uses transparent dielectric substrate PET to replace the traditional dielectric plate, so as to realize the visibility of the overall structure. Transparent electromagnetic absorber meets the development advantages of modern stealth materials, such as thin, light, high, wide and transparent, so it is widely studied by modern researchers and has important military and civilian values. SUMMARY

[0009] The purpose of the present application is to provide a transparent and wave-absorbing integrated electromagnetic material unit based on a complementary structure, which realizes electromagnetic protection in the optical window of photoelectric and display devices.

[0010] The technical solution of the present application is as follows: a transparent and wave-absorbing integrated electromagnetic material unit based on a complementary structure, which includes top, middle and bottom dielectric layers arranged in parallel and spaced apart from top to bottom, and the same circular ring-shaped periodic transparent ITO film is arranged on the upper surface of the top dielectric layer and the upper surface of the bottom dielectric layer, and the circular ring-shaped complementary structure periodic transparent ITO film is arranged on the upper surface of the middle dielectric layer, and the air layer is arranged between the adjacent two dielectric layers.

[0011] Compared with the prior art, the present application has the following advantages:

[0012] (1) The present application is arranged from top to bottom by a top dielectric layer, a circular ITO film, an intermediate dielectric layer, a circular complementary ITO film, a bottom dielectric layer and a circular ITO film, forming a laminated structure, the top dielectric layer, the intermediate dielectric layer and the bottom dielectric layer all adopt high-transmittance PET, and the film adopts good-transmittance indium tin oxide material. Compared with the prior art, while ensuring the wave absorption bandwidth and the absorption rate, the electromagnetic wave transmission and good light transmission performance are realized, and the application range is expanded.

[0013] (2) The present application is composed of an array of a circular ring and its complementary structure composed of a plurality of periodically arranged transparent resistance films, the ITO film of the top layer and the intermediate layer has a square resistance of 160Ω / sq, the bottom layer adopts a transparent film with a square resistance of 5Ω / sq, it has a high resistivity and a low resistivity, so it can be regarded as a metal conductor for frequency selection. When the electromagnetic wave is incident on the structure proposed in the present application, the bottom layer circular ring structure will exhibit the effect of a low-pass filter, forming a low-frequency transmission passband, which can be used for effective transmission of communication signals; the intermediate layer and the top layer structure adopt a resistive film with a large square resistance, which is used for absorbing electromagnetic waves, and the air layer is used for matching the impedance of the free space, finally producing a broadband wave absorption effect. The structure proposed in the present application realizes signal transmission and electromagnetic wave absorption in different frequency bands, and the ITO film used has the characteristics of light weight and thin thickness, while ensuring the communication effect of the equipment, the broadband wave absorption effect and the high wave absorption rate, the thickness and weight of the electromagnetic material are reduced, which is more practical and convenient for integration with a microwave system.

[0014] (3) The present application is composed of a resistive ITO film and a PET dielectric layer, compared with the prior art, it has the advantages of high mechanical hardness, good chemical stability, etc., can ensure the stability of performance for a long time, has a longer service life, and is cheap, easy to process and manufacture, and has a very high cost performance. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a three-dimensional structure schematic diagram of the present application.

[0016] Figure 2 is a side view of the present application.

[0017] Figure 3 is a top view of the present application.

[0018] Figure 4 is a scattering coefficient curve diagram of the present application.

[0019] Figure 5 is a wave transmittance curve diagram of the present application.

[0020] Figure 6 is a wave absorption rate schematic diagram of the present application under different incident angles. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the protection scope of the present application.

[0022] It should be noted that all directionality indications (such as up, down, left, right, front, back, and the like) in the embodiments of the present application are only used to explain the relative position relationship, movement condition, and the like between components in a certain posture (as shown in the drawings), and if the certain posture changes, the directionality indications also change accordingly.

[0023] In addition, the descriptions such as “first”, “second” and the like in the present application are only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features defined as “first”, “second” can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of “plurality” is at least two, for example, two, three, and the like, unless otherwise explicitly and specifically limited.

[0024] In the present application, unless otherwise explicitly specified and limited, the terms “connection”, “fixing” and the like should be understood in a broad sense, for example, “fixing” can be fixed connection, or detachable connection, or integral; “connection” can be mechanical connection, or electrical connection. For a person of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0025] In addition, the technical solutions of each embodiment of the present application can be combined with each other, but it must be based on the fact that a person of ordinary skill in the art can realize it, and when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, and is not within the protection scope required by the present application.

[0026] The specific embodiments, technical difficulties and points of the present application will be further introduced below in combination with the design examples.

[0027] In combination with Figure 1 and Figure 2The application discloses a transparent and wave-absorbing integrated electromagnetic material unit based on a complementary structure, which comprises top, middle and bottom dielectric layers arranged in parallel, and the same transparent ITO film in a circular ring shape is arranged on the upper surfaces of the top and bottom dielectric layers in a periodic manner, and the transparent ITO film in a circular ring complementary structure is arranged on the upper surface of the middle dielectric layer in a periodic manner, and an air layer is arranged between the adjacent two dielectric layers.

[0028] The dielectric layer material is PET, the relative dielectric constant is 3, and the loss tangent is 0.06.

[0029] The transparent ITO film in a circular ring shape is a circular ring transparent resistive film printed on the top and bottom dielectric layers by using a magnetic sputtering technology, and the films are arranged in a periodic manner in two perpendicular directions on a plane.

[0030] The transparent ITO film in a circular ring complementary structure is a circular ring gap etched on the middle dielectric layer covered with the transparent ITO film, and the size and arrangement of the gap are consistent with the circular ring ITO film unit on the top and bottom dielectric layers, thus the gap is called a circular ring complementary structure.

[0031] In combination Figure 1 With the transparent and wave-absorbing integrated electromagnetic material unit based on the complementary structure, the top dielectric layer, the circular ring ITO film, the middle dielectric layer, the circular ring complementary ITO film and the bottom dielectric layer and the circular ring ITO film are arranged from top to bottom to form a laminated structure. The ITO film is printed on the upper surfaces of the bottom and top dielectric layers by using a magnetic sputtering technology, a plurality of circular ring units are arranged in a periodic manner, and the circular ring complementary structure is also printed on the upper surface of the middle dielectric layer by using the magnetic sputtering technology. Figure 2 And Figure 3 In the embodiment, the thickness of the dielectric layer is t=0.175mm, the thickness of the first air layer is h1=5mm, the thickness of the second air layer is h2=4mm, the side length of the dielectric layer is p=14.5mm, the inner diameter of the circular ring is r1=4.2mm, the outer diameter of the circular ring is r2=7mm, the square resistance of the ITO film on the middle and top dielectric layers is R S2 = R S1 =160Ω / sq, and the square resistance of the ITO film on the third substrate layer is R S3 =5Ω / sq. The dielectric layer is PET with a relative dielectric constant of 3 and a thickness of 0.175mm.

[0032] Referring to Figure 4 is to utilize Figure 1The scattering coefficients of the periodic structure under different incident angles in the frequency range of 0.5-18 GHz are simulated by using a commercial electromagnetic simulation software CST Studio Suite, wherein the horizontal coordinate represents frequency, and the vertical coordinate represents the size of scattered electromagnetic energy. Figure 5 It can be seen that the transmission coefficients under different incident angles, when the electromagnetic wave is normally incident, the insertion loss in the frequency range of 0.5-2.5 GHz is less than 3 dB. Figure 6 The wave absorption rates of the structure design proposed in the application under different angles, wherein the horizontal coordinate is frequency, and the vertical coordinate is the absorption rate of electromagnetic energy, it can be seen that the absorption rate of the application to the electromagnetic wave in the frequency range of 6-18 GHz is greater than 90%, which can well shield the signal of the local detection radar and realize invisibility.

[0033] The simulation results show that the absolute working bandwidth of the application reaches 12 GHz, the relative bandwidth reaches 100%, the absorption rate in the wave absorption bandwidth is greater than 90%, and the thickness of the wave absorber is only 0.25λ0 (wherein λ0 is the wavelength corresponding to the wave absorption center frequency), compared with the prior art, while ensuring the wave absorption rate and wave absorption bandwidth, the application has an electromagnetic wave transmission window, and has higher light transmittance and smaller weight.

[0034] The above only describes the preferred embodiments of the application patent, and does not limit the application patent. It should be noted that any improvement and modification made within the spirit and principles of the application patent should be regarded as within the protection scope of the application patent.

Claims

1. A transparent integrated electromagnetic material unit based on a complementary structure, characterized in that: It includes a top dielectric layer, an intermediate dielectric layer and a bottom dielectric layer that are parallel and spaced from top to bottom. The top dielectric layer and the bottom dielectric layer are respectively provided with the same transparent ITO film arranged in a circular periodic pattern. The intermediate dielectric layer is provided with a transparent ITO film arranged in a circular complementary structure periodic pattern. There is an air layer between two adjacent dielectric layers. The dielectric layer material is PET, with a relative permittivity of 3 and a loss tangent of 0.

06. The circularly arranged transparent ITO thin film is a circularly arranged transparent resistive thin film printed on the top and bottom dielectric layers using magnetic sputtering technology. These films are arranged periodically in two perpendicular directions on a plane. The transparent ITO film with a periodic arrangement of circular complementary structures is formed by etching circular slots on an intermediate dielectric layer that is fully covered with transparent ITO film. The size and arrangement of these slots are consistent with the circular ITO film units on the top and bottom dielectric layers. The sheet resistance of the ITO thin film on the intermediate and top dielectric layers is R. S2 = R S1 =160Ω / sq, used to dissipate electromagnetic waves, and the air layer is used to match the impedance of free space, producing a broadband wave absorption effect; The sheet resistance of the ITO film on the third matrix layer is R. S3 =5Ω / sq, exhibiting the effect of a low-pass filter, forming a low-frequency transmission passband.

2. The transparent wave-absorbing and wave-transmitting integrated electromagnetic material unit based on complementary structure according to claim 1, characterized in that: The dielectric layer thickness is t=0.175mm, the first air layer thickness is h1=5mm, the second air layer thickness is h2=4mm, the dielectric layer side length is p=14.5mm, the inner diameter of the ring is r1=4.2mm, and the outer diameter of the ring is r2=7mm.

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