Metamaterial broadband microwave absorber

Abstract

The invention provides a metamaterial broadband microwave absorber which comprises a metal bottom plate and a dielectric layer located above the metal bottom plate, and a plurality of semiconductor periodic structure units are periodically laid and arranged on the upper surface of the dielectric layer; each semiconductor periodic structure unit comprises a segmented ring-shaped structure and a cross-shaped structure which are connected with each other; the segmented circular ring structure comprises at least three segmented circular rings which are concentrically arranged and have different radiuses; each segmentation circular ring is divided into four arc pairs which are symmetrically distributed by a cross-shaped structure; the metal bottom plate is made of a conductive metal material; the dielectric layer is made of an insulating electrolyte material; and the product of the thickness and the conductivity of the semiconductor periodic structure unit is a fixed value. By adopting the metamaterial absorber, the problems of narrow band and polarization sensitivity in the existing metamaterial absorber can be relieved.

Description

Technical Field

[0001] The present invention relates to the technical field of metamaterial electromagnetic wave applications, and in particular to a metamaterial broadband microwave absorber. Background Art

[0002] Metamaterials are artificial materials that can exhibit electromagnetic properties such as negative refractive index and inverse Doppler effect that natural materials do not have through fine design of the structure on a subwavelength scale. Among the many metamaterial devices that have been proposed, metamaterial absorbers can almost completely absorb electromagnetic waves incident on their surfaces, and have a wide range of applications in communications, radar stealth, sensors, and energy collection. The core principle of metamaterial absorbers is to design specific structures and materials so that the incident electromagnetic waves resonate in the material and are completely absorbed by the material, avoiding reflection and transmission of electromagnetic waves, and ultimately converting microwave energy into heat or other forms of energy. However, most existing metamaterial absorbers have problems such as narrowband (only good absorption of electromagnetic waves within a narrow frequency range) and polarization sensitivity. Summary of the invention

[0003] In view of this, an object of the present invention is to provide a metamaterial broadband microwave absorber to alleviate the problems of narrowband and polarization sensitivity existing in existing metamaterial absorbers.

[0004] An embodiment of the present invention provides a metamaterial broadband microwave absorber, comprising: a metal base plate and a dielectric layer located above the metal base plate, wherein a plurality of semiconductor periodic structural units are periodically arranged on the upper surface of the dielectric layer; the semiconductor periodic structural unit comprises a segmented circular ring structure and a cross structure connected to each other; the segmented circular ring structure comprises at least three segmented circular rings arranged concentrically and having different radii, and the segmented spacing of the segmented circular rings decreases as the radius increases; each segmented circular ring is divided into four symmetrically distributed circular arc pairs by the cross structure; each circular arc pair consists of two symmetrically distributed circular arcs, the two circular arcs of the same circular arc pair have equal angles and each has one end that is not connected at the corresponding segmentation position; the metal base plate is made of conductive metal material; the dielectric layer is made of insulating electrolyte material; the product of the thickness and conductivity of the semiconductor periodic structural unit is a fixed value.

[0005] A metamaterial broadband microwave absorber provided in an embodiment of the present invention adopts a sandwich structure of "semiconductor periodic structure-dielectric layer-metal base plate", and changes the metal metamaterial periodic structure adopted by the existing metamaterial absorber into a symmetrically designed semiconductor periodic structure, and the semiconductor periodic structure unit is at least covered with three layers of split rings. Compared with the existing metamaterial absorber, the internal resistance of the metamaterial periodic structure is increased, and the absorption peak is increased, thereby enhancing the absorption effect of microwave energy and expanding the absorption bandwidth, and can also realize the non-polarization direction absorption of microwave energy, and has broadband and polarization-insensitive microwave absorption characteristics.

[0006] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description, claims and drawings.

[0007] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0009] Figure 1 This is a schematic diagram of a unit structure of a metamaterial broadband microwave absorber according to an embodiment of the present invention;

[0010] Figure 2 A schematic diagram of the structure of a semiconductor periodic structure unit in an embodiment of the present invention;

[0011] Figure 3 This is a power absorption spectrum of the first metamaterial broadband microwave absorber in the embodiment of the present invention at 4 GHz-8 GHz;

[0012] Figure 4 This is a distribution diagram of electromagnetic wave loss power density of the first metamaterial broadband microwave absorber in an embodiment of the present invention when the electric field polarization direction of the incident electromagnetic wave is in the X-axis direction;

[0013] Figure 5 This is a distribution diagram of electromagnetic wave loss power density of the first metamaterial broadband microwave absorber in an embodiment of the present invention when the electric field polarization direction of the incident electromagnetic wave is in the Y-axis direction;

[0014] Figure 6 This is a power absorption spectrum of the second metamaterial broadband microwave absorber in the embodiment of the present invention at 1 GHz-5 GHz;

[0015] Figure 7 This is the power absorption spectrum of the third metamaterial broadband microwave absorber in the embodiment of the present invention at 8 GHz-16 GHz.

[0016] Icons: 100 - metal base plate; 200 - dielectric layer; 300 - semiconductor periodic structure unit; 310 - segmented circular ring structure; 311 - first segmented circular ring; 312 - second segmented circular ring; 313 - third segmented circular ring; 320 - cross structure. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be clearly and completely described in combination with the embodiments below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] The embodiment of the present invention discloses a metamaterial broadband microwave absorber, the structure of which is shown in FIG. Figure 1 and Figure 2 As shown, it comprises: a metal base plate 100 and a dielectric layer 200 located above the metal base plate 100, wherein a plurality of semiconductor periodic structure units 300 are periodically arranged on the upper surface of the dielectric layer 200; the semiconductor periodic structure unit 300 comprises a segmented circular ring structure 310 and a cross structure 320 connected to each other; the segmented circular ring structure 310 comprises at least three segmented circular rings arranged concentrically and having different radii, and the segmented spacing of the segmented circular rings decreases as the radius increases; each segmented circular ring is divided into four symmetrically distributed circular arc pairs by the cross structure 320; each circular arc pair consists of two symmetrically distributed circular arcs, and the two circular arcs of the same circular arc pair have equal angles and each has one end that is not connected at the corresponding segmentation position;

[0019] The metal base plate 100 may be made of conductive metal materials, such as copper, gold, silver, aluminum, etc., which is not limited.

[0020] Since the conductivity value and thickness of the semiconductor material are closely related, it is necessary to ensure that the product of the conductivity and thickness of the semiconductor material is a certain value, that is, the product of the thickness and conductivity of the semiconductor periodic structure unit 300 is a fixed value. When the conductivity of the material selected for the semiconductor periodic structure unit 300 increases, the thickness of the semiconductor periodic structure unit 300 decreases accordingly; when the conductivity of the material selected for the semiconductor periodic structure unit 300 decreases, the thickness of the semiconductor periodic structure unit 300 increases accordingly. For example, when the conductivity of the semiconductor periodic structure unit 300 is selected as 300S / m, the thickness of the semiconductor periodic structure unit 300 can be designed to be 0.1mm; when the conductivity of the semiconductor periodic structure unit 300 is selected as 3000S / m, the thickness of the semiconductor periodic structure unit 300 can be designed to be 0.01mm.

[0021] The dielectric layer 200 may be made of insulating dielectric materials, such as FR-4 materials, polyimide materials, 92ML materials, etc., without limitation. When the dielectric layer 200 is made of different dielectric materials, the thickness of the dielectric layer 200 may vary; for example Figure 1 and Figure 2 As shown, if the dielectric layer 200 is made of FR-4 material, the thickness of the dielectric layer 200 can be about 5.5 mm; if the dielectric layer 200 is made of polyimide material, the thickness of the dielectric layer 200 can be about 6.5 mm; if the dielectric layer 200 is made of 92ML material, the thickness of the dielectric layer 200 can be about 4.7 mm.

[0022] The above-mentioned metamaterial broadband microwave absorber adopts a sandwich structure of "semiconductor periodic structure-dielectric layer-metal base plate", which changes the metal metamaterial periodic structure used in the existing metamaterial absorber into a symmetrically designed semiconductor periodic structure, and the semiconductor periodic structure unit is at least covered with three layers of split rings. Compared with the existing metamaterial absorber, the internal resistance of the metamaterial periodic structure is increased, and the absorption peak is increased, thereby enhancing the absorption effect of microwave energy and expanding the absorption bandwidth. It can also realize the non-polarization direction absorption of microwave energy, and has broadband and polarization-insensitive microwave absorption characteristics.

[0023] As a possible implementation, the radius difference between every two adjacent divided circular rings in the divided circular ring structure 310 is equal.

[0024] As a possible implementation, see Figure 1 and Figure 2 As shown, the segmented circular ring structure 310 may have three segmented circular rings, and the three segmented circular rings are a first segmented circular ring 311, a second segmented circular ring 312 and a third segmented circular ring 313, whose radii increase successively.

[0025] For example Figure 2 As shown, Figure 2 The middle split circular ring structure 310 is composed of a first split circular ring 311, a second split circular ring 312, and a third split circular ring 313. The respective radii of the first split circular ring 311, the second split circular ring 312, and the third split circular ring 313 are r3, r2, and r1 respectively, where r3 < r2 < r1, and r2 - r3 = r1 - r2.

[0026] As a possible implementation, referring to Figure 1 and Figure 2 shown, the split positions of the first split circular ring 311, the second split circular ring 312, and the third split circular ring 313 corresponding to the same circular arc pair are on the same straight line as the central position of the cross-shaped structure 320, and the circular arc angles of the circular arc pairs corresponding to the first split circular ring 311, the second split circular ring 312, and the third split circular ring 313 increase in sequence.

[0027] Continuing the previous example, as Figure 2 shown, Figure 2 in the first split circular ring 311, the second split circular ring 312, and the third split circular ring 313, the circular arc pairs corresponding to each are each composed of two symmetrically distributed circular arcs. The two circular arcs of the same circular arc pair have equal angles and one end of each is not connected at the corresponding split position. The circular arc angles of the circular arc pairs corresponding to the first split circular ring 311, the second split circular ring 312, and the third split circular ring 313 (i.e., Figure 2 the θ3, θ2, and θ1 in

[0028] Specifically, referring to Figure 1 and Figure 2 shown, the circular arc angles of the circular arc pairs corresponding to the first split circular ring 311, the second split circular ring 312, and the third split circular ring 313 (i.e., Figure 2 the θ3, θ2, and θ1 in

[0029] For ease of understanding, the structure and technical effects of the above-mentioned metamaterial broadband microwave absorber are described exemplarily below with a specific application as an example.

[0030] As one of the application examples, the embodiment of the present invention provides a first type of metamaterial broadband microwave absorber. Referring to Figure 1 and Figure 2As shown, the metamaterial broadband microwave absorber may include a metal bottom plate 100 and a dielectric layer 200 located above the metal bottom plate 100, wherein a plurality of semiconductor periodic structure units 300 are periodically arranged on the upper surface of the dielectric layer 200; the semiconductor periodic structure unit 300 is composed of a segmented circular ring structure 310 and a cross-shaped structure 320 connected to each other; the segmented circular ring structure 310 is composed of a first segmented circular ring 311, a second segmented circular ring 312 and a third segmented circular ring 313 which are arranged concentrically and have increasing radii in sequence, and the segmentation spacings of the first segmented circular ring 311, the second segmented circular ring 312 and the third segmented circular ring 313 are respectively reduced in sequence; ... The segmented circular rings 313 are each divided into four symmetrically distributed circular arc pairs by the cross-shaped structure 320; the segmentation positions corresponding to the same circular arc pair of the first segmented circular ring 311, the second segmented circular ring 312 and the third segmented circular ring 313 are on the same straight line as the center position of the cross-shaped structure 320; the circular arc pairs corresponding to the first segmented circular ring 311, the second segmented circular ring 312 and the third segmented circular ring 313 are each composed of two symmetrically distributed circular arcs, the two circular arcs of the same circular arc pair have equal angles and each has one end that is not connected at the corresponding segmentation position; the circular arc angles (i.e. Figure 2 θ3, θ2 and θ1) are specifically θ3=36°, θ2=40°, θ1=44°; the metal base plate 100 is made of copper; the dielectric layer 200 is made of FR-4 material, and the thickness of the dielectric layer 200 is h=5.5 mm.

[0031] See also Figure 2 As shown, in the first metamaterial broadband microwave absorber, the segmented circular ring structure corresponds to the concentric square area on the upper surface of the dielectric layer 200 (i.e. Figure 2 The side length of the square area in the figure is a=22mm; the radii of the first dividing ring 311, the second dividing ring 312 and the third dividing ring 313 (i.e., r3, r2 and r1) are specifically r3=6mm, r2=8mm, r10mm; the line width of the semiconductor periodic structure unit 300 is w=0.5mm; the thickness of the semiconductor periodic structure unit 300 is d=0.1mm, and the conductivity of the semiconductor periodic structure unit 300 is 300S / m.

[0032] In order to verify the microwave absorption effect of the metamaterial broadband microwave absorber, a microwave absorption experiment can be carried out on the first metamaterial broadband microwave absorber. The microwave absorption experiment is mainly used to verify the broadband and polarization-insensitive microwave absorption characteristics of the metamaterial broadband microwave absorber. The main operation mode of the microwave absorption experiment can be divided into the following two parts:

[0033] (1) When an electromagnetic wave is incident on the first metamaterial broadband microwave absorber, the power absorption spectrum of the first metamaterial broadband microwave absorber within a certain frequency range can be obtained by analyzing the absorption power, reflection power and incident power of the metamaterial broadband microwave absorber, such as Figure 3 As shown, it can be seen that the electromagnetic wave absorption rate (i.e. the ratio of absorbed power to incident power) of the metamaterial broadband microwave absorber in the C-band (i.e. the frequency range of 4GHz-8GHz) is on average more than 90%, which can well achieve broadband microwave absorption.

[0034] (2) When the electromagnetic wave is incident on the first metamaterial broadband microwave absorber, the corresponding electromagnetic wave loss power density distribution diagram can be obtained by analyzing the electromagnetic wave loss power density distribution when the electric field polarization direction of the incident electromagnetic wave is in the X-axis direction and the Y-axis direction, such as Figure 4 and Figure 5 As shown, it can be seen that the electromagnetic wave loss power density distribution results of the metamaterial broadband microwave absorber are completely symmetrical, which can verify that the symmetry of the structural design of the metamaterial broadband microwave absorber can make the metamaterial broadband microwave absorber present the characteristics of non-polarization.

[0035] The microwave absorption experiment finally verifies that the first metamaterial broadband microwave absorber provided by the embodiment of the present invention has a non-polarized broadband microwave absorption effect with high absorptivity in the C-band.

[0036] As another application example, the present invention provides a second metamaterial broadband microwave absorber, see Figure 1 and Figure 2 As shown, the differences between the second metamaterial broadband microwave absorber and the first metamaterial broadband microwave absorber are a=12mm, r1=5mm, r2=4mm, r3=3mm, w=0.3mm, h=2.6mm, and the material properties and other structural parameters are consistent with the first metamaterial broadband microwave absorber.

[0037] In order to verify the microwave absorption effect of the metamaterial broadband microwave absorber, a microwave absorption experiment can be carried out on the second metamaterial broadband microwave absorber. The microwave absorption experiment is mainly to verify the broadband microwave absorption characteristics of the metamaterial broadband microwave absorber. The main operation mode of the microwave absorption experiment is: when the electromagnetic wave is incident on the second metamaterial broadband microwave absorber, the power absorption spectrum of the first metamaterial broadband microwave absorber within a certain frequency range can be obtained by analyzing the absorption power, reflection power and incident power of the metamaterial broadband microwave absorber. Figure 6As shown, it can be seen that the metamaterial broadband microwave absorber can achieve good microwave absorption effect (ie, the average electromagnetic wave absorption rate reaches more than 90%) in the P band (ie, the frequency range of 2GHz-4GHz), and can well realize broadband microwave absorption.

[0038] The microwave absorption experiment finally verifies that the second metamaterial broadband microwave absorber provided by the embodiment of the present invention has a broadband microwave absorption effect with high absorptivity in the P band.

[0039] As another application example, the present invention provides a second metamaterial broadband microwave absorber, see Figure 1 and Figure 2 As shown, the differences between the second metamaterial broadband microwave absorber and the first metamaterial broadband microwave absorber are a=42mm; r1=20mm; r2=16mm; r3=12mm; w=1.0mm; h=11mm, and the material properties and other structural parameters are consistent with the first metamaterial broadband microwave absorber.

[0040] In order to verify the microwave absorption effect of the metamaterial broadband microwave absorber, a microwave absorption experiment can be carried out on the third metamaterial broadband microwave absorber. The microwave absorption experiment is mainly to verify the broadband microwave absorption characteristics of the metamaterial broadband microwave absorber. The main operation mode of the microwave absorption experiment is: when the electromagnetic wave is incident on the third metamaterial broadband microwave absorber, the power absorption spectrum of the first metamaterial broadband microwave absorber within a certain frequency range can be obtained by analyzing the absorption power, reflection power and incident power of the metamaterial broadband microwave absorber. Figure 7 As shown, it can be seen that the metamaterial broadband microwave absorber can achieve good microwave absorption effect (i.e., the average electromagnetic wave absorption rate reaches more than 90%) in the X-band (i.e., the frequency range of 8GHz-16GHz), and can well achieve broadband microwave absorption. The microwave absorption experiment finally verifies that the second metamaterial broadband microwave absorber provided by the embodiment of the present invention has a broadband microwave absorption effect with high absorption rate in the P-band.

[0041] In summary, compared with general metamaterial absorbers, the most important feature of the metamaterial broadband microwave absorber of the present invention is that the metal metamaterial periodic structure surface is changed to a semiconductor periodic structure surface, and the structure form can be further expanded. Compared with general microwave absorbers, the metamaterial broadband microwave absorber of the present invention has the following advantages:

[0042] 1) By changing the traditional metal metamaterial periodic structure surface to the semiconductor metamaterial periodic structure surface of the present invention, the internal resistance of the metamaterial periodic structure unit can be increased, thereby increasing the absorption of electromagnetic energy and expanding the absorption bandwidth.

[0043] 2) The semiconductor metamaterial structural unit adopts a structural design of circular rings with different radii, which can increase the absorption peak and thus expand the absorption bandwidth.

[0044] 3) The semiconductor metamaterial structural unit adopts a symmetrical design, and the structure of the semiconductor metamaterial structural unit in the lateral direction is completely consistent with the structure in the longitudinal direction, ultimately achieving non-polarized directional absorption of microwave energy.

[0045] Unless otherwise specifically stated, the relative steps, numerical expressions and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present invention.

[0046] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0047] Finally, it should be noted that the above-described embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention is described in detail with reference to the above-described embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-described embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A metamaterial broadband microwave absorber, characterized in that: include: A metal base plate and a dielectric layer located above it, wherein a plurality of semiconductor periodic structural units are periodically arranged on the upper surface of the dielectric layer; the semiconductor periodic structural unit comprises a segmented circular ring structure and a cross structure connected to each other; the segmented circular ring structure comprises at least three segmented circular rings arranged concentrically and having different radii, and the segmented spacing of the segmented circular rings decreases as the radius increases; each segmented circular ring is divided into four symmetrically distributed arc pairs by the cross structure; each arc pair consists of two symmetrically distributed arcs, the two arcs of the same arc pair have equal angles and each has one end that is not connected at the corresponding segmentation position; the metal base plate is made of conductive metal material; the dielectric layer is made of insulating electrolyte material; the product of the thickness and conductivity of the semiconductor periodic structural unit is a fixed value.

2. The metamaterial broadband microwave absorber according to claim 1, characterized in that: The radius difference between every two adjacent segmented circular rings in the segmented circular ring structure is equal.

3. The metamaterial broadband microwave absorber according to claim 1, characterized in that: The segmented circular ring structure has three segmented circular rings, and the three segmented circular rings are a first segmented circular ring, a second segmented circular ring and a third segmented circular ring, the radii of which increase successively.

4. The metamaterial broadband microwave absorber according to claim 3, characterized in that: The division positions of the first divided circular ring, the second divided circular ring and the third divided circular ring corresponding to the same arc pair are on the same straight line as the center position of the cross structure, and the arc angles of the arc pairs corresponding to the first divided circular ring, the second divided circular ring and the third divided circular ring increase successively.

5. The metamaterial broadband microwave absorber according to claim 4, characterized in that: The arc angles of the arc pairs corresponding to the first segmented circular ring, the second segmented circular ring and the third segmented circular ring are 36°, 40° and 44° respectively.

6. The metamaterial broadband microwave absorber according to claim 1, characterized in that: The dielectric layer is made of one of the following materials: FR-4 material, polyimide material, and 92ML material.

7. The metamaterial broadband microwave absorber according to claim 5, characterized in that: The side length of the concentric square area of ​​the segmented circular ring structure corresponding to the upper surface of the dielectric layer is 22 mm, the thickness of the semiconductor periodic structure unit is 0.1 mm, the line width of the semiconductor periodic structure unit is 0.5 mm, and the radii of the first segmented ring, the second segmented ring and the third segmented ring are 6 mm, 8 mm and 10 mm respectively.

8. The metamaterial broadband microwave absorber according to claim 5, characterized in that: The side length of the concentric square area of ​​the segmented circular ring structure corresponding to the upper surface of the dielectric layer is 12 mm, the thickness of the semiconductor periodic structure unit is 2.6 mm, the line width of the semiconductor periodic structure unit is 0.3 mm, and the radii of the first segmented ring, the second segmented ring and the third segmented ring are 3 mm, 4 mm and 5 mm respectively.

9. The metamaterial broadband microwave absorber according to claim 5, characterized in that: The side length of the concentric square area of ​​the segmented circular ring structure corresponding to the upper surface of the dielectric layer is 42 mm, the thickness of the semiconductor periodic structure unit is 11 mm, the line width of the semiconductor periodic structure unit is 1 mm, and the radii of the first segmented circular ring, the second segmented circular ring and the third segmented circular ring are 12 mm, 16 mm and 20 mm respectively.

10. The metamaterial broadband microwave absorber according to claim 6, characterized in that: If the dielectric layer is made of FR-4 material, the thickness of the dielectric layer is 5.5 mm; if the dielectric layer is made of polyimide material, the thickness of the dielectric layer is 6.5 mm; if the dielectric layer is made of 92ML material, the thickness of the dielectric layer is 4.7 mm.

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