Double-layer-structure low-frequency wave-absorbing material and preparation method thereof

Abstract

The invention discloses a low-frequency wave-absorbing material with a double-layer structure. The low-frequency wave-absorbing material comprises a metal back plate, a magnetic material layer and a patterned layer which are sequentially laminated, the patterned layer comprises a dielectric substrate and a metal patterned pattern layer arranged on the surface of the dielectric substrate, and the metal patterned pattern layer comprises rectangular pattern units arranged in an array; each rectangular pattern unit comprises a first rectangular pattern located at the center, a first notch square pattern located at the first corner, a second notch square pattern located at the second corner, a third notch square pattern located at the third corner and a fourth notch square pattern located at the fourth corner. The magnetic material layer and the patterned layer are combined, selective transmission of electromagnetic waves is achieved through reasonable structural design of the patterned layer, the transmitted electromagnetic waves enter the magnetic material layer to be attenuated and absorbed, and effective absorption of the magnetic material layer to the electromagnetic waves is promoted through combination of the magnetic material layer and the patterned layer.

Description

Technical Field

[0001] The present application relates to the field of material technology, and in particular to a double-layer low-frequency absorbing material and a preparation method thereof. Background Art

[0002] Microwaves, as an important carrier of long-distance communication, have promoted the development of social informatization. Frequency, as a basic property of microwaves, affects the information transmission function of microwaves. In the increasingly popular 5G communication, high-frequency microwaves of 24GHz~100GHz have short wavelengths and high information density, which can improve the information transmission capacity, but the large transmission loss affects the transmission distance; medium-frequency microwaves of 2GHz~5GHz have moderate wavelengths and strong coverage, becoming the main frequency band for portable mobile devices; low-frequency microwaves of 600MHz~2GHz have long wavelengths and good penetration, providing guarantee for long-distance communication between cities. With the popularization of microwave applications, electromagnetic pollution problems are inevitable, affecting the normal use of precision equipment and even human health; in the military field, the intricate modern battlefields are covered with radar signals of different frequencies, and radar detection technology is gradually developing towards long-distance low-frequency detection, threatening the safety of weapons and equipment, which requires radar absorbing materials to absorb microwaves that have negative effects.

[0003] At present, radar absorbing materials used in the 8~18GHz frequency band are already very mature, but for electromagnetic waves below 4GHz, traditional carbonyl iron powder absorbers are difficult to achieve high-performance absorption, and the application of radar absorbing materials in various types of equipment has thickness and weight requirements. Therefore, it is extremely important to develop thin and efficient radar absorbing materials for absorption in the 1GHz~5GHz frequency band. In order to improve the low-frequency absorption performance in the 1~5GHz frequency band, it is necessary to select magnetic fillers with better magnetic permeability performance. Limited by the intrinsic properties of low-frequency magnetic materials, their high magnetic permeability often has high electrical conductivity, which easily causes impedance mismatch and cannot achieve efficient absorption in the 1~4GHz frequency band, especially 1~2GHz. CN111755828A uses a multi-layer FSS structure combined with a magnetic material layer to achieve an electromagnetic wave reflectivity of less than -10dB from 2GHz to 3.6GHz at a thickness of 2.5mm. Compared with traditional radar absorbing coating materials, the combination of metamaterials and absorbing coatings has improved the low-frequency absorbing performance, but there is still room for improvement in achieving the absorption of thin-layer low-frequency absorbing materials in the range of 1GHz to 4GHz.

[0004] Therefore, it is an urgent problem for those skilled in the art to provide an absorbing material that can better absorb low-frequency electromagnetic waves. Summary of the invention

[0005] In view of this, the present application provides a double-layer low-frequency absorbing material, which is combined with a patterned layer and a magnetic material layer. The patterned layer selectively transmits electromagnetic waves, and the transmitted electromagnetic waves are absorbed by the magnetic material layer, thereby achieving effective absorption of 1GHz~4GHz electromagnetic waves, which is beneficial for application in the military field.

[0006] The present application provides a double-layer structure low-frequency wave absorbing material, comprising a metal back plate, a magnetic material layer and a patterned layer stacked in sequence;

[0007] The patterned layer includes a dielectric substrate and a metal patterned graphic layer disposed on the surface of the dielectric substrate, wherein the metal patterned graphic layer includes rectangular pattern units arranged in an array;

[0008] The rectangular pattern unit includes a first rectangular pattern at the center, a first notched square pattern at the first corner, a second notched square pattern at the second corner, a third notched square pattern at the third corner, and a fourth notched square pattern at the fourth corner;

[0009] The four corners of the first rectangular pattern are respectively provided with a first rectangular notch, a second rectangular notch, a third rectangular notch and a fourth rectangular notch;

[0010] The first notch square pattern has a square notch, which is arranged opposite to the first rectangular notch;

[0011] The second notch square pattern has a square notch, which is arranged opposite to the second rectangular notch;

[0012] The third notch square pattern has a square notch, which is arranged opposite to the third rectangular notch;

[0013] The notch of the fourth notch square pattern is square and is arranged opposite to the fourth rectangular notch.

[0014] In some specific implementations, the rectangular pattern unit is a square pattern unit, and the side length of the square pattern unit is 20 mm to 40 mm.

[0015] In some specific implementations, the first rectangular pattern is a first square pattern, the first rectangular notch is a first square notch, the second rectangular notch is a second square notch, the third rectangular notch is a third rectangular notch, the fourth rectangular notch is a fourth square notch, and the side length of the first square pattern is 4 mm to 6 mm; the side lengths of the first square notch, the second square notch, the third rectangular notch and the fourth square notch are each independently 0.5 mm to 2 mm.

[0016] In some specific implementations, the side lengths of the first notched square pattern, the second notched square pattern, the third notched square pattern and the fourth notched square pattern are each independently 7 mm to 9 mm; the side lengths of the notches of the first notched square pattern, the notches of the second notched square pattern, the third notched square pattern and the fourth notched square pattern are each independently 2 mm to 4 mm.

[0017] In some specific implementations, the gap between adjacent rectangular pattern units is 3 mm to 7 mm.

[0018] In some specific implementations, the interval between two adjacent ones of the first notch square pattern, the second notch square pattern, the third notch square pattern and the fourth notch square pattern is 5 mm to 7 mm.

[0019] In some specific implementations, the thickness of the metal patterned graphic layer is 0.6 mm to 1 mm.

[0020] In some specific implementations, the thickness of the rectangular pattern unit is 0.1 mm to 0.3 mm.

[0021] In some specific implementations, the thickness of the magnetic material layer is 0.4 mm to 0.9 mm.

[0022] In some specific implementations, the magnetic material layer includes a resin matrix and an absorbent; the absorbent includes one or more of soft magnetic alloy powder, carbonyl iron or ferrosoferric oxide; the resin matrix includes epoxy resin and / or polyurethane; the metal material in the metal patterned graphic layer includes copper and / or aluminum; the dielectric substrate includes polyimide and / or polyetheretherketone; and the metal backplane is made of aluminum alloy.

[0023] The present application also provides a method for preparing a double-layer low-frequency absorbing material, comprising:

[0024] inkjet printing a first rectangular pattern, a first notched square pattern, a second notched square pattern, a third notched square pattern, and a fourth notched square pattern onto a dielectric substrate to obtain a patterned layer;

[0025] The magnetic material is coated on the surface of the metal back plate, and the patterned layer is hot-pressed and bonded to the upper surface of the magnetic material to obtain a double-layer structure low-frequency wave absorbing material.

[0026] The present application combines a magnetic material layer and a patterned layer, and realizes selective transmission of electromagnetic waves through reasonable structural design of the patterned layer. The transmitted electromagnetic waves enter the magnetic material layer and are attenuated and absorbed. Through the combination of the two, it is equivalent to the parallel connection of the reactance element formed by the patterned layer and the equivalent impedance element formed by the magnetic material layer. The reactance element produces a resonance effect, which promotes the effective absorption of electromagnetic waves by the magnetic material layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A cross-sectional view of a double-layer low-frequency absorbing material provided in an embodiment of the present application;

[0028] Figure 2 A schematic diagram of a rectangular pattern unit of a double-layer low-frequency absorbing material provided in an embodiment of the present application;

[0029] Figure 3 A schematic diagram of the side length of a rectangular pattern unit of a double-layer low-frequency absorbing material provided in an embodiment of the present application;

[0030] Figure 4 This is a reflectivity test chart of the double-layer low-frequency absorbing material provided in Example 1 of the present application;

[0031] Figure 5 This is a reflectivity test chart of the double-layer low-frequency absorbing material provided in Example 2 of the present application;

[0032] Figure 6 This is a reflectivity test chart of the double-layer low-frequency absorbing material provided in Example 3 of the present application. DETAILED DESCRIPTION

[0033] It should be understood that the expression "one or more of..." includes each of the items recited after the expression individually and in various different combinations of two or more of the recited items, unless otherwise understood from the context and usage. The expression "and / or" in combination with three or more recited items should be understood to have the same meaning, unless otherwise understood from the context.

[0034] The use of the terms "comprising", "having" or "containing", including their grammatical synonyms, should generally be understood as open and non-restrictive, for example not excluding other unrecited elements or steps, unless otherwise specifically stated or otherwise understood from the context.

[0035] It should be understood that the order of steps or the order in which certain actions are performed is not important as long as the application is still operable. In addition, two or more steps or actions can be performed simultaneously.

[0036] The use of any and all examples or exemplary language, such as "for example" or "including", herein is intended only to better illustrate the present application and does not limit the scope of the present application unless the claims are set forth. No language in this specification should be construed as indicating that any non-claimed element is essential to the practice of the present application.

[0037] In addition, the numerical ranges and parameters used to define the present application are approximate values, and the relevant values ​​in the specific embodiments have been presented as accurately as possible. However, any numerical value inherently inevitably contains standard deviations due to individual test methods. Therefore, unless otherwise expressly stated, it should be understood that all ranges, quantities, values ​​and percentages used in this disclosure are modified by "about". Here, "about" generally refers to the actual value within plus or minus 10%, 5%, 1% or 0.5% of a specific value or range.

[0038] The present application provides a double-layer structure low-frequency wave absorbing material, comprising a metal back plate, a magnetic material layer and a patterned layer stacked in sequence;

[0039] The patterned layer includes a dielectric substrate and a metal patterned graphic layer disposed on the surface of the dielectric substrate, wherein the metal patterned graphic layer includes rectangular pattern units arranged in an array;

[0040] The rectangular pattern unit includes a first rectangular pattern at the center, a first notched square pattern at the first corner, a second notched square pattern at the second corner, a third notched square pattern at the third corner, and a fourth notched square pattern at the fourth corner;

[0041] The four corners of the first rectangular pattern are respectively provided with a first rectangular notch, a second rectangular notch, a third rectangular notch and a fourth rectangular notch;

[0042] The first notch square pattern has a square notch, which is arranged opposite to the first rectangular notch;

[0043] The second notch square pattern has a square notch, which is arranged opposite to the second rectangular notch;

[0044] The third notch square pattern has a square notch, which is arranged opposite to the third rectangular notch;

[0045] The notch of the fourth notch square pattern is square and is arranged opposite to the fourth rectangular notch.

[0046] The present application designs a rectangular pattern unit, surrounds the first notched square pattern, the second notched square pattern, the third notched square pattern and the fourth notched square pattern in the direction of the four corners of the first rectangular pattern, and forms an inductive element to achieve selective transmission of electromagnetic waves. The inductive element is connected in parallel with the equivalent impedance element of the magnetic material layer. The transmitted electromagnetic waves enter the magnetic material layer and are attenuated and absorbed through electric loss and magnetic loss, thereby achieving control of the absorption peak position and absorption efficiency at 1GHz~4GHz.

[0047] See also Figure 1 , Figure 1 A cross-sectional view of a double-layer low-frequency absorbing material provided in an embodiment of the present application. 1 is a metal backplane, 2 is a magnetic material layer, and 3 is a patterned layer. In some specific implementations, the thickness of the double-layer low-frequency absorbing material is 1.3 mm to 2 mm, preferably 1.4 mm to 1.8 mm, and more preferably 1.5 mm to 1.6 mm. Compared with the existing absorbing technology, the double-layer low-frequency absorbing material provided in the present application has a simple structure, a material thickness of no more than 2 mm, and has good absorbing performance in the frequency range of 1 to 4 GHz.

[0048] In some specific implementations, the metal back plate 1 is made of aluminum alloy. In some specific implementations, the thickness of the metal back plate 1 is 6 mm to 10 mm, preferably 8 mm.

[0049] In some specific implementations, the magnetic material layer 2 includes a resin matrix and an absorbent; the absorbent includes one or more of soft magnetic alloy powder, carbonyl iron or ferroferric oxide, preferably soft magnetic alloy powder; the resin matrix includes epoxy resin and / or polyurethane. In some specific implementations, the thickness of the magnetic material layer 2 is 0.4 mm to 0.9 mm, preferably 0.45 mm to 0.88 mm, and more preferably 0.5 mm to 0.85 mm; the absorption peak position and absorption efficiency can be controlled at 1 GHz to 4 GHz by adjusting the thickness of the magnetic material layer 2.

[0050] In some specific implementations, the thickness of the patterned layer 3 is 0.6mm to 1mm, preferably 0.7mm to 0.9mm, and more preferably 0.8mm to 0.85mm. In some specific implementations, the patterned layer 3 includes a dielectric substrate and a metal patterned graphic layer arranged on the surface of the dielectric substrate. The dielectric substrate is polyimide and / or polyetheretherketone. In some specific implementations, the material of the metal in the metal patterned graphic layer is copper and / or aluminum. In some specific implementations, the thickness of the rectangular pattern unit is 0.1mm to 0.3mm, preferably 0.12mm to 0.25mm, and more preferably 0.15mm to 0.2mm.

[0051] The metal patterned graphic layer includes rectangular pattern units arranged in an array, and the same rectangular pattern units are arranged in rows and columns to form an array.

[0052] In some specific implementations, the rectangular pattern unit is a square pattern unit, and the side length of the square pattern unit is 20 mm to 40 mm, preferably 22 mm to 38 mm, and more preferably 24 mm to 30 mm. Figure 2 , Figure 2 A schematic diagram of a rectangular pattern unit of a double-layer low-frequency absorbing material provided in an embodiment of the present application, wherein the rectangular pattern unit of the double-layer low-frequency absorbing material comprises a first square pattern 10 located at the center, a first notched square pattern 11 located at a first corner of the rectangular pattern unit, a second notched square pattern 21 located at a second corner of the rectangular pattern unit, a third notched square pattern 31 located at a third corner of the rectangular pattern unit, and a fourth notched square pattern 41 located at a fourth corner of the rectangular pattern unit;

[0053] The four corners of the first square pattern 10 are respectively provided with a first square notch 101, a second square notch 102, a third square notch 103 and a fourth square notch 104;

[0054] The notch 111 of the first notch square pattern 11 is square and is arranged opposite to the first square notch 101;

[0055] The notch 211 of the second notch square pattern 21 is square and is arranged opposite to the second square notch 102;

[0056] The notch 311 of the third notch square pattern 31 is square and is arranged opposite to the third square notch 103;

[0057] The notch 411 of the fourth notch square pattern 41 is square and is arranged opposite to the fourth square notch 104 .

[0058] In some specific implementations, the first square pattern 10 is located at the center of the square pattern unit; the first notch square pattern 11 is located at the upper left corner of the square pattern unit; the second notch square pattern 21 is located at the upper right corner of the square pattern unit; the first notch square pattern 11 and the second notch square pattern 21 are centrally symmetrical around the center point of the square pattern unit; the third notch square pattern 31 is located at the lower left corner of the square pattern unit; the fourth notch square pattern 41 is located at the lower right corner of the square pattern unit, the third notch square pattern 31 and the fourth notch square pattern 41 are centrally symmetrical around the center point of the square pattern unit, and the first square notch 101, the second square notch 102, the third square notch 103 and the fourth square notch 104 are not in contact with the first square pattern 10.

[0059] See also Figure 3 , Figure 3Schematic diagram of the side length of the rectangular pattern unit of the double-layer low-frequency absorbing material provided in the embodiment of the present application. In some specific implementations, the first square pattern 10 is a structure in which a complete square with a side length of a+2b lacks four small squares with a side length of b at the four corners, and the side lengths b of the missing four small squares are respectively the side lengths of the first square gap 101, the second square gap 102, the third rectangular gap 103 and the fourth square gap 104 (the gaps 101~104 are of the same size, all are squares, and the side lengths are b), and the side lengths of the first square gap 101, the second square gap 102, the third rectangular gap 103 and the fourth square gap 104 are independently b; the side length of the square minus the side lengths of the two missing small squares is a, which is the side length of the first square pattern 10; the four sides of the first square pattern 10 are equal, and the side lengths of the first square gap 101, the second square gap 102, the third rectangular gap 103 and the fourth square gap 104 are equal. In some specific implementations, the first notched square pattern 11, the second notched square pattern 21, the third notched square pattern 31 and the fourth notched square pattern 41 are all squares with a side length c, lacking a small square with a side length e, and the side length c of the square is the side length of the first notched square pattern 11, the second notched square pattern 21, the third notched square pattern 31 and the fourth notched square pattern 41, and the side length of the square minus the side length of a small square is the side length d of the notch side of the first notched square pattern 11, the notch side of the second notched square pattern 21, the notch side of the third notched square pattern 31 and the notch side of the fourth notched square pattern 41.Among them, a is the side length of the first square pattern 10, and the side length of the first square pattern 10 is 4mm to 6mm, preferably 5mm to 5.5mm; b is the side length of the first square notch 101, the second square notch 102, the third square notch 103 and the fourth square notch 104, b is 0.5mm to 2mm, preferably 1mm to 1.5mm; c is the side length of the first notch square pattern 11, the second notch square pattern 21, the third notch square pattern 31 and the fourth notch square pattern 41, c is 7mm to 9mm, preferably 7.5mm to 8.5mm, more preferably 8mm to 8.2mm; d is the side length of the notch edge of the first notch square pattern 11, the notch edge of the second notch square pattern 21, the notch edge of the third notch square pattern 31 and the notch edge of the fourth notch square pattern 41, d is 4mm to 6mm, preferably 4.5mm to 5.8mm , more preferably 5mm to 5.5mm; e is the side length of the notch of the first notch square pattern 11, the notch of the second notch square pattern 21, the notch of the third notch square pattern 31 and the notch of the fourth notch square pattern 41, the side length e of the notch of the first notch square pattern 11, the notch of the second notch square pattern 21, the notch of the third notch square pattern 31 and the notch of the fourth notch square pattern 41 is 2mm to 4mm, preferably 2.2mm to 3.5mm, more preferably 2.5mm to 3mm, the notch of the first notch square pattern 11 is arranged opposite to the first square notch 101; the notch of the second notch square pattern 21 is arranged opposite to the second square notch 102; the notch of the third notch square pattern 31 is arranged opposite to the third square notch 103; the notch of the fourth notch square pattern 41 is arranged opposite to the fourth square notch 104. In some specific implementations, the first notch square pattern 11, the second notch square pattern 21, the third notch square pattern 31 and the fourth notch square pattern 41 are of the same size and are rotationally symmetrical about the center of the rectangular pattern unit. f is the first notched square pattern 11, the second notched square pattern 21, the third notched square pattern 31 and the fourth notched square pattern 41, and the spacing between two adjacent ones is 5mm to 7mm, preferably 5.5mm to 6.5mm, and more preferably 6mm. The rectangular pattern unit is an axisymmetric and centrally symmetrical figure. Through the reasonable structural design of the rectangular pattern unit, the selective penetration of electromagnetic waves is realized, and the penetrated electromagnetic waves enter the magnetic material layer 2 and are attenuated and absorbed by electrical loss and magnetic loss. The combination of the two is equivalent to the parallel connection of the reactance element formed by the patterned layer 3 and the equivalent impedance element formed by the magnetic material layer 2. At the appropriate frequency, the reactance element produces a resonance effect, which promotes the effective absorption of electromagnetic waves by the magnetic material layer 2.

[0060] The present application also provides a method for preparing a double-layer low-frequency absorbing material, comprising:

[0061] inkjet printing a first rectangular pattern, a first notched square pattern, a second notched square pattern, a third notched square pattern, and a fourth notched square pattern onto a dielectric substrate to obtain a patterned layer;

[0062] The magnetic material is coated on the surface of the metal back plate, and the patterned layer is hot-pressed and bonded to the upper surface of the magnetic material to obtain a double-layer structure low-frequency wave absorbing material.

[0063] The present application uses a metal backplane, a magnetic material, a metal patch and a dielectric substrate as raw materials to prepare a double-layer low-frequency absorbing material, wherein the material of the metal backplane includes but is not limited to aluminum alloy, and the present application has no special requirements for the selection of the material of the metal backplane 1. In some specific implementations, the magnetic material layer 2 is a composite of an absorbent and a resin matrix. In some specific implementations, the absorbent includes but is not limited to one or more of soft magnetic alloy powder, carbonyl iron or ferroferric oxide, preferably soft magnetic alloy powder, and the present application has no special requirements for the selection of the absorbent. The higher the magnetic permeability of the magnetic material layer 2, the stronger the ability to lose low-frequency electromagnetic waves. In order to achieve low-frequency absorption, the effect of selecting soft magnetic alloy powder as an absorbent is better. In some specific implementations, the resin matrix includes epoxy resin and / or polyurethane, preferably epoxy resin, and the present application has no special requirements for the selection of the resin matrix. In some specific implementations, the material of the metal patch includes but is not limited to copper and / or aluminum, and the present application has no special requirements for the selection of the material of the metal backplane 1. In some specific implementations, the conductivity of the metal patch is 5.6×10 7 S / m. In some specific implementations, the dielectric substrate includes but is not limited to polyimide and / or polyetheretherketone, and the present application has no special requirements for the selection of the dielectric substrate. In some specific implementations, the thickness of the dielectric substrate is 0.8 mm, the dielectric constant is 3.5, the dielectric loss tangent is 0.0027, and the magnetic permeability is 1.

[0064] The present application is further described below in conjunction with the following embodiments. The protection scope of the present application is not limited by the following embodiments.

[0065] Example 1

[0066] This embodiment provides a double-layer low-frequency wave absorbing material, comprising a metal back plate 1, a magnetic material layer 2 and a patterned layer 3 stacked in sequence;

[0067] The patterned layer 3 includes a dielectric substrate and a metal patterned graphic layer arranged on the surface of the dielectric substrate. The metal patterned graphic layer includes rectangular pattern units arranged in an array. The rectangular pattern units are composed of metal patches. When the array is arranged, all the metal patches are not in contact. The material of the metal patches is copper. The conductivity of the five metal patches is the same, which is 5.6×10 7S / m.

[0068] The rectangular pattern unit includes a first square pattern 10 at the center, a first notched square pattern 11 at the first corner, a second notched square pattern 21 at the second corner, a third notched square pattern 31 at the third corner, and a fourth notched square pattern 41 at the fourth corner;

[0069] The four corners of the first square pattern 10 are respectively provided with a first square notch 101, a second square notch 102, a third square notch 103 and a fourth square notch 104;

[0070] The first square notch pattern 11 has a square notch, which is arranged opposite to the first square notch 101;

[0071] The second square notch pattern 21 has a square notch, which is arranged opposite to the second square notch 102;

[0072] The third notch square pattern 31 has a square notch, which is arranged opposite to the third square notch 103;

[0073] The fourth square notch pattern 41 has a square notch, and is arranged opposite to the fourth square notch 104 .

[0074] The thickness of the magnetic material layer 2 is 0.5mm, and the thickness of the patterned layer 3 is 0.8mm. In the patterned layer 3, the side length of the rectangular pattern unit is 24mm, the gap between adjacent rectangular pattern units is 5mm, and the thickness of the rectangular pattern unit is 0.15mm. The side length a of the first square pattern 10 is 5.5mm, the side length b of the first square notch 101, the second square notch 102, the third square notch 103 and the fourth square notch 104 is 1.0mm, the first notch square pattern 11, the second notch square pattern 21, the third notch square pattern 31 and the fourth notch square pattern 41 are of the same size and are rotationally symmetrical around the center of the rectangular pattern unit. The side length c of the first notch square pattern 11, the second notch square pattern 21, the third notch square pattern 31 and the fourth notch square pattern 41 is 8mm, and the first notch square pattern 10 is 5.5mm. The length d of the notch edge of the square pattern 11, the notch edge of the second notch square pattern 21, the notch edge of the third notch square pattern 31 and the notch edge of the fourth notch square pattern 41 is 5.5 mm, the length e of the notch of the first notch square pattern 11, the notch of the second notch square pattern 21, the notch of the third notch square pattern 31 and the notch of the fourth notch square pattern 41 is 2.5 mm, and the spacing f between two adjacent ones of the first notch square pattern 11, the second notch square pattern 21, the third notch square pattern 31 and the fourth notch square pattern 41 is 6 mm. The thickness of the metal back plate 1 is 8 mm.

[0075] The preparation method of the double-layer low-frequency absorbing material comprises: providing a metal back plate 1, spraying a magnetic material on the metal back plate 1 by compressed air to form a magnetic material layer 2, and curing and molding; a metal patch made of copper is located at the center according to the first square pattern 10, the first notch square pattern 11 is located at the first corner, the second notch square pattern 21 is located at the second corner, the third notch square pattern 31 is located at the third corner, and the fourth notch square pattern 41 is located at the fourth corner, and inkjet printing is performed on the surface of a dielectric substrate with the above side length to obtain a rectangular pattern unit to form a patterned layer 3, and the patterned layer 3 is laid on the magnetic material layer 2 to obtain a double-layer low-frequency absorbing material.

[0076] The reflectivity test of the obtained double-layer low-frequency absorbing material is performed. The reflectivity test graph of the double-layer low-frequency absorbing material is shown in FIG. Figure 4 shown.

[0077] Example 2

[0078] This embodiment provides a double-layer low-frequency wave absorbing material, comprising a metal back plate 1, a magnetic material layer 2 and a patterned layer 3 stacked in sequence;

[0079] The patterned layer 3 includes a dielectric substrate and a metal patterned graphic layer arranged on the surface of the dielectric substrate. The metal patterned graphic layer includes rectangular pattern units arranged in an array. The rectangular pattern units are composed of metal patches. When the array is arranged, all the metal patches are not in contact. The material of the metal patches is copper. The conductivity of the five metal patches is the same, which is 5.6×10 7 S / m.

[0080] The rectangular pattern unit includes a first square pattern 10 at the center, a first notched square pattern 11 at the first corner, a second notched square pattern 21 at the second corner, a third notched square pattern 31 at the third corner, and a fourth notched square pattern 41 at the fourth corner;

[0081] The four corners of the first square pattern 10 are respectively provided with a first square notch 101, a second square notch 102, a third square notch 103 and a fourth square notch 104;

[0082] The first square notch pattern 11 has a square notch, which is arranged opposite to the first square notch 101;

[0083] The second square notch pattern 21 has a square notch, which is arranged opposite to the second square notch 102;

[0084] The third notch square pattern 31 has a square notch, which is arranged opposite to the third square notch 103;

[0085] The fourth square notch pattern 41 has a square notch, and is arranged opposite to the fourth square notch 104 .

[0086] The thickness of the magnetic material layer 2 is 0.8 mm, and the thickness of the patterned layer 3 is 0.8 mm. In the patterned layer 3, the side length of the rectangular pattern unit is 24 mm, the gap between adjacent rectangular pattern units is 6 mm, and the thickness of the rectangular pattern unit is 0.2 mm. The side length a of the first square pattern 10 is 5 mm, the side length b of the first square notch 101, the second square notch 102, the third square notch 103 and the fourth square notch 104 is 1.5 mm, the first notch square pattern 11, the second notch square pattern 21, the third notch square pattern 31 and the fourth notch square pattern 41 are of the same size, and are rotationally symmetrical about the center of the rectangular pattern unit. The side length c of the first notch square pattern 11, the second notch square pattern 21, the third notch square pattern 31 and the fourth notch square pattern 41 is 8 mm, and the first notch square pattern 10 is 5 mm. The length d of the notch edge of the square pattern 11, the notch edge of the second notch square pattern 21, the notch edge of the third notch square pattern 31 and the notch edge of the fourth notch square pattern 41 is 5.5 mm, the length e of the notch of the first notch square pattern 11, the notch of the second notch square pattern 21, the notch of the third notch square pattern 31 and the notch of the fourth notch square pattern 41 is 2.5 mm, and the spacing f between two adjacent ones of the first notch square pattern 11, the second notch square pattern 21, the third notch square pattern 31 and the fourth notch square pattern 41 is 6 mm. The thickness of the metal back plate 1 is 6 mm.

[0087] The preparation method of the double-layer low-frequency absorbing material comprises: providing a metal back plate 1, spraying a magnetic material on the metal back plate 1 by compressed air to form a magnetic material layer 2, and curing and molding; a metal patch made of copper is located at the center according to the first square pattern 10, the first notch square pattern 11 is located at the first corner, the second notch square pattern 21 is located at the second corner, the third notch square pattern 31 is located at the third corner, and the fourth notch square pattern 41 is located at the fourth corner, and inkjet printing is performed on the surface of a dielectric substrate with the above side length to obtain a rectangular pattern unit to form a patterned layer 3, and the patterned layer 3 is laid on the magnetic material layer 2 to obtain a double-layer low-frequency absorbing material.

[0088] The reflectivity test of the obtained double-layer low-frequency absorbing material is performed. The reflectivity test graph of the double-layer low-frequency absorbing material is shown in FIG. Figure 5 shown.

[0089] Example 3

[0090] This embodiment provides a double-layer low-frequency wave absorbing material, comprising a metal back plate 1, a magnetic material layer 2 and a patterned layer 3 stacked in sequence;

[0091] The patterned layer 3 includes a dielectric substrate and a metal patterned graphic layer arranged on the surface of the dielectric substrate. The metal patterned graphic layer includes rectangular pattern units arranged in an array. The rectangular pattern units are composed of metal patches. When the array is arranged, all the metal patches are not in contact. The material of the metal patches is copper. The conductivity of the five metal patches is the same, which is 5.6×10 7 S / m.

[0092] The rectangular pattern unit includes a first square pattern 10 at the center, a first notched square pattern 11 at the first corner, a second notched square pattern 21 at the second corner, a third notched square pattern 31 at the third corner, and a fourth notched square pattern 41 at the fourth corner;

[0093] The four corners of the first square pattern 10 are respectively provided with a first square notch 101, a second square notch 102, a third square notch 103 and a fourth square notch 104;

[0094] The first square notch pattern 11 has a square notch, which is arranged opposite to the first square notch 101;

[0095] The second square notch pattern 21 has a square notch, which is arranged opposite to the second square notch 102;

[0096] The third notch square pattern 31 has a square notch, which is arranged opposite to the third square notch 103;

[0097] The fourth square notch pattern 41 has a square notch, and is arranged opposite to the fourth square notch 104 .

[0098] The thickness of the magnetic material layer 2 is 0.85mm, and the thickness of the patterned layer 3 is 0.8mm. In the patterned layer 3, the side length of the rectangular pattern unit is 24mm, the gap between adjacent rectangular pattern units is 4mm, and the thickness of the rectangular pattern unit is 0.2mm. The side length a of the first square pattern 10 is 5mm, the side length b of the first square notch 101, the second square notch 102, the third square notch 103 and the fourth square notch 104 is 1.5mm, the first notch square pattern 11, the second notch square pattern 21, the third notch square pattern 31 and the fourth notch square pattern 41 are of the same size, and are rotationally symmetrical about the center of the rectangular pattern unit. The side length c of the first notch square pattern 11, the second notch square pattern 21, the third notch square pattern 31 and the fourth notch square pattern 41 is 8mm, and the first notch square pattern 10 is 5mm. The length d of the notch edge of the square pattern 11, the notch edge of the second notch square pattern 21, the notch edge of the third notch square pattern 31 and the notch edge of the fourth notch square pattern 41 is 5 mm, the length e of the notch of the first notch square pattern 11, the notch of the second notch square pattern 21, the notch of the third notch square pattern 31 and the notch of the fourth notch square pattern 41 is 3 mm, and the spacing f between two adjacent ones of the first notch square pattern 11, the second notch square pattern 21, the third notch square pattern 31 and the fourth notch square pattern 41 is 6 mm. The thickness of the metal back plate 1 is 6 mm.

[0099] The preparation method of the double-layer low-frequency absorbing material comprises: providing a metal back plate 1, spraying a magnetic material on the metal back plate 1 by compressed air to form a magnetic material layer 2, and curing and molding; a metal patch made of copper is located at the center according to the first square pattern 10, the first notch square pattern 11 is located at the first corner, the second notch square pattern 21 is located at the second corner, the third notch square pattern 31 is located at the third corner, and the fourth notch square pattern 41 is located at the fourth corner, and inkjet printing is performed on the surface of a dielectric substrate with the above side length to obtain a rectangular pattern unit to form a patterned layer 3, and the patterned layer 3 is laid on the magnetic material layer 2 to obtain a double-layer low-frequency absorbing material.

[0100] The reflectivity test of the obtained double-layer low-frequency absorbing material is performed. The reflectivity test graph of the double-layer low-frequency absorbing material is shown in FIG. Figure 6 shown.

[0101] The performance test of the double-layer low-frequency absorbing materials provided in Examples 1 to 3 was carried out, and the test method was as follows:

[0102] Reflectivity: vertical reflectivity test is carried out according to the bow method of GJB 2038A;

[0103] The performance test results are shown in Table 1.

[0104] Table 1

[0105]

[0106] According to the data in Table 1, Examples 1 to 3 use the double-layer low-frequency absorbing material provided by the present technical solution, and their reflectivity at 1-2 GHz frequencies is ≤-1.6 dB, their reflectivity at 2-4 GHz frequencies is ≤-4.5 dB, and their reflectivity at 4-8 GHz frequencies is ≤-3.3 dB. By adjusting the parameters of the magnetic material layer 2 and the patterned layer 3, the reflectivity performance can be adjusted.

[0107] The above is only a preferred specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can make equivalent substitutions or changes within the technical scope disclosed in the present application according to the technical solution and application concept of the present application, which should be covered by the protection scope of the present application.

Claims

1. A double-layer low-frequency absorbing material, characterized in that: It includes a metal back plate, a magnetic material layer and a patterned layer stacked in sequence; The patterned layer includes a dielectric substrate and a metal patterned graphic layer disposed on the surface of the dielectric substrate, wherein the metal patterned graphic layer includes rectangular pattern units arranged in an array; The rectangular pattern unit includes a first rectangular pattern at the center, a first notched square pattern at the first corner, a second notched square pattern at the second corner, a third notched square pattern at the third corner, and a fourth notched square pattern at the fourth corner; The four corners of the first rectangular pattern are respectively provided with a first rectangular notch, a second rectangular notch, a third rectangular notch and a fourth rectangular notch; The first notch square pattern has a square notch, which is arranged opposite to the first rectangular notch; The second notch square pattern has a square notch, which is arranged opposite to the second rectangular notch; The third notch square pattern has a square notch, which is arranged opposite to the third rectangular notch; The notch of the fourth notch square pattern is square and is arranged opposite to the fourth rectangular notch.

2. The double-layer low-frequency absorbing material according to claim 1, characterized in that: The rectangular pattern unit is a square pattern unit, and the side length of the square pattern unit is 20 mm to 40 mm.

3. The double-layer low-frequency absorbing material according to claim 1, characterized in that: The first rectangular pattern is a first square pattern, the first rectangular notch is a first square notch, the second rectangular notch is a second square notch, the third rectangular notch is a third rectangular notch, and the fourth rectangular notch is a fourth square notch. The side length of the first square pattern is 4 mm to 6 mm; the side lengths of the first square notch, the second square notch, the third rectangular notch and the fourth square notch are each independently 0.5 mm to 2 mm.

4. The double-layer low-frequency absorbing material according to claim 1, characterized in that: The side lengths of the first notched square pattern, the second notched square pattern, the third notched square pattern and the fourth notched square pattern are each independently 7 mm to 9 mm; the side lengths of the notches of the first notched square pattern, the second notched square pattern, the third notched square pattern and the fourth notched square pattern are each independently 2 mm to 4 mm.

5. The double-layer low-frequency absorbing material according to claim 1, characterized in that: The gap between adjacent rectangular pattern units is 3 mm to 7 mm.

6. The double-layer low-frequency absorbing material according to claim 1, characterized in that: In the first notch square pattern, the second notch square pattern, the third notch square pattern and the fourth notch square pattern, the interval between two adjacent ones is 5 mm to 7 mm.

7. The double-layer low-frequency absorbing material according to claim 1, characterized in that: The thickness of the metal patterned graphic layer is 0.6 mm to 1 mm.

8. The double-layer low-frequency absorbing material according to claim 1, characterized in that: The thickness of the rectangular pattern unit is 0.1 mm to 0.3 mm.

9. The double-layer low-frequency absorbing material according to claim 1, characterized in that: The thickness of the magnetic material layer is 0.4 mm to 0.9 mm.

10. The double-layer low-frequency absorbing material according to claim 1, characterized in that: The magnetic material layer includes a resin matrix and an absorbent; the absorbent includes one or more of soft magnetic alloy powder, carbonyl iron or ferroferric oxide; the resin matrix includes epoxy resin and / or polyurethane; the metal material in the metal patterned graphic layer includes copper and / or aluminum; the dielectric substrate includes polyimide and / or polyetheretherketone; the material of the metal backplane is aluminum alloy.

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