Planar slow wave structure integrated with graphene metamaterial wave absorber

Abstract

The invention discloses a planar slow wave structure of an integrated graphene metamaterial wave absorber, and belongs to the field of microwave devices. A novel planar slow wave structure loaded with a graphene metamaterial wave absorber is designed by utilizing the perfect wave absorbing characteristic and good heat conductivity coefficient of a graphene metamaterial, electromagnetic waves are propagated in a microstrip line of the structure, and a wave absorber which is parallel to the transmission direction of the electromagnetic waves and has frequency selectivity is arranged below the structure. The designed planar slow wave structure of the integrated graphene metamaterial wave absorber conforms to the miniaturization and integration development trend of traveling wave tubes, and has wide application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of microwave devices, and in particular to a planar slow-wave structure integrating a graphene metamaterial absorber. Background Art

[0002] The back-wave oscillation and harmonic output in the planar periodic slow-wave structure traveling wave tube device will reduce the output performance of the traveling wave tube and affect the working stability of the traveling wave tube. The existing solution is to set an attenuator (add a dielectric coating layer on the dielectric substrate at a certain length on the slow-wave structure). The traditional coating layer attenuator relies on its high loss tangent angle to absorb electromagnetic waves. It is not very sensitive to frequency. The absorption rate of the back wave, high-order harmonics and working signals is the same, which means that while the former two are insufficiently absorbed, the working signal may be overabsorbed, and the manufacturing process is difficult. Therefore, the attenuator in the current traveling wave tube has the problem of no frequency selective absorption characteristics (both the working frequency and high-order harmonics are absorbed, reducing the output gain of the traveling wave tube). The existing electromagnetic absorbing structures are mainly based on electromagnetic waves incident vertically or in a certain direction. The incident angle is generally less than 90°, and as the incident angle increases, the absorbing effect decreases significantly, so it cannot be directly applied to the planar periodic slow-wave structure traveling wave tube. Summary of the invention

[0003] The present invention utilizes the perfect wave absorbing characteristics and good thermal conductivity of graphene metamaterials to propose a planar slow-wave structure of an integrated graphene metamaterial absorber. In the absorber with the planar slow-wave structure, electromagnetic waves propagate in a microstrip line, and there is an absorbing structure parallel to the transmission direction of the electromagnetic waves below, which conforms to the development trend of miniaturization and integration of traveling wave tube devices and has broad application prospects.

[0004] An embodiment of the present invention provides a planar slow-wave structure with an integrated graphene metamaterial absorber, wherein the planar slow-wave structure comprises from top to bottom: a zigzag microstrip line, a slow-wave structure dielectric layer, a graphene absorbing pattern layer, a graphene absorbing dielectric layer and a metal bottom plate, wherein two ends of the zigzag microstrip line are respectively connected to a signal input port and a signal output port; the zigzag microstrip line and the slow-wave structure dielectric layer constitute a zigzag line slow-wave structure, and the graphene absorbing pattern layer, the graphene absorbing dielectric layer and the metal bottom plate constitute a planar absorbing structure.

[0005] Optionally, in one embodiment of the present invention, the meandering microstrip line is composed of a plurality of metal lines with periodic cross sections of U-shape, V-shape or N-shape arranged at equal intervals.

[0006] Optionally, in one embodiment of the present invention, the material of the meander microstrip line is copper or gold.

[0007] Optionally, in one embodiment of the present invention, the material of the slow-wave structure dielectric layer includes quartz, boron nitride, or Rogers plate.

[0008] Optionally, in one embodiment of the present invention, the graphene absorbing pattern layer is a high-conductivity graphene film etched into a resonant ring array structure with complementary openings, and the conductivity of the graphene film is ≥1.1*10 6 S / m.

[0009] Optionally, in one embodiment of the present invention, the material of the graphene absorbing medium layer includes quartz and boron nitride.

[0010] In an embodiment of the present invention, a planar slow-wave structure with integrated graphene metamaterial absorber is designed by utilizing the perfect wave absorption characteristics and good thermal conductivity of graphene metamaterial. Electromagnetic waves propagate in the microstrip line of the structure, and there is a frequency-selective absorber parallel to the transmission direction of the electromagnetic wave below. The designed planar slow-wave structure with integrated graphene metamaterial absorber conforms to the development trend of miniaturization and integration of traveling wave tubes and has broad application prospects.

[0011] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0013] Figure 1 A simulation modeling diagram of a planar slow-wave structure of an integrated graphene metamaterial absorber provided according to an embodiment of the present invention;

[0014] Figure 2 A side view of a planar slow-wave structure of an integrated graphene metamaterial absorber according to an embodiment of the present invention;

[0015] Figure 3 A schematic diagram of a single graphene complementary open resonant ring and its array structure loaded in an embodiment of the present invention;

[0016] Figure 4 This is a graph of the absorptivity of an absorber based on a single graphene complementary open ring resonator array loaded according to an embodiment of the present invention;

[0017] Figure 5 A schematic diagram of a loaded double graphene open resonant ring array and its array structure according to an embodiment of the present invention;

[0018] Figure 6This is a graph showing the absorption rate of an absorber based on a loaded double graphene open resonant ring array according to an embodiment of the present invention. DETAILED DESCRIPTION

[0019] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0020] The back-wave oscillation and harmonic output in the planar periodic slow-wave structure traveling wave tube device will reduce the output performance of the traveling wave tube and affect the working stability of the traveling wave tube. The general existing solution is to set an attenuator (add a dielectric coating layer on the dielectric substrate at a certain length on the slow-wave structure). The traditional coating layer attenuator relies on its high loss tangent angle to absorb electromagnetic waves. It is not very sensitive to frequency and has the same absorption rate for back-wave, high-order harmonics and working signals, which means that while the former two are insufficiently absorbed, the working signal may be overabsorbed, and the manufacturing process is difficult. In response to this problem, the present invention proposes a planar slow-wave structure with an integrated graphene metamaterial absorber.

[0021] like Figure 1 and Figure 2 As shown, the planar slow-wave structure of the integrated graphene metamaterial absorber includes from top to bottom: a zigzag microstrip line 1, a slow-wave structure dielectric layer 2, a graphene absorbing pattern layer 3, a graphene absorbing dielectric layer 4 and a metal bottom plate 5, and the two ends of the zigzag microstrip line are respectively connected to a signal input port 6 and a signal output port 7. The zigzag microstrip line 1 and the slow-wave structure dielectric layer 2 form a zigzag line slow-wave structure, and the graphene absorbing pattern layer 3, the graphene absorbing dielectric layer 4 and the metal bottom plate 5 are a planar absorbing structure.

[0022] In an embodiment of the present invention, the meandering microstrip line is composed of a plurality of metal lines with periodic cross sections of U-shape, V-shape or N-shape arranged at equal intervals, and the material of the meandering microstrip line 1 is metal materials such as copper and gold.

[0023] In the embodiment of the present invention, the material of the slow-wave structure dielectric layer includes quartz, boron nitride, and Rogers plate. The material of the slow-wave structure dielectric layer is quartz stone, and the relative dielectric constant is 3.8.

[0024] In the embodiment of the present invention, the graphene absorbing pattern layer is a high conductivity graphene film, and its conductivity is 1.38*10 6 S / m, the thickness of the graphene film is 17μm, and it can be patterned using laser etching technology.

[0025] In an embodiment of the present invention, the graphene absorbing dielectric layer material includes quartz and boron nitride, the material is quartz stone, and the relative dielectric constant is 3.8.

[0026] In an embodiment of the present invention, the metal bottom plate is a metal ground plane, which is generally an inner wall of a rectangular waveguide.

[0027] In the embodiment of the present invention, the graphene absorbing pattern layer is a high conductivity graphene film etched into a resonant ring array structure with complementary openings, and the conductivity of the graphene film is ≥1.1*10 6 S / m.

[0028] Figure 3 To etch the high conductivity graphene film into a unit structure complementary to the square open ring, the white part is the etched graphene, and its width is w. The gap of the open ring is g. x and p y Directions are arranged into array structures of different combinations, such as p x There are 3 unit structures in the direction, p y If there are three unit structures in the direction, it is called a 3*3 array. CST 2021 3D electromagnetic simulation software is used to test the transmission characteristics of the 9*3 array and calculate its absorption rate. By adjusting the structural parameters to observe the changes in the absorption spectrum, the law of electromagnetic wave absorption by different absorbing structural units can be determined. The adjusted structural parameters include the length p of the unit structure x , width p y , the width w of the etched graphene and the gap g of the open ring.

[0029] like Figure 4 As shown, by appropriate adjustment Figure 3 With the structural parameters in , an absorption rate of 98% was achieved at 79.2 GHz, 92% at 129.8 GHz, and 87% at 186.5 GHz.

[0030] like Figure 5 As shown in the figure, the high conductivity graphene film is etched into a unit structure complementary to the square opening ring, where the white part is the etched graphene, forming two opening rings with opposite opening directions, and their widths are w1 and w2 respectively. The gaps of the opening rings are g1 and g2. x1 and p y2 Directions are arranged into array structures of different combinations, such as p x1 There are 3 unit structures in the direction, p y1If there are three unit structures in the direction, it is called a 3*3 array. CST 2021 3D electromagnetic simulation software is used to test the transmission characteristics of the 9*3 array and calculate its absorption rate. By adjusting the structural parameters to observe the changes in the absorption spectrum, the law of electromagnetic wave absorption by different absorbing structural units can be determined. The adjusted structural parameters include the length p of the unit structure x1 , width p y1 , the etched graphene widths w1 and w2, and the gaps of the open rings g1 and g2.

[0031] like Figure 6 As shown, by appropriate adjustment Figure 5 The structural parameters in the figure can achieve double absorption peaks. Specifically, 98% absorption rate is achieved at 79.2 GHz, 92% absorption rate is achieved at 129.8 GHz, and 87% absorption rate is achieved at 186.5 GHz.

[0032] The embodiment of the present invention proposes a planar slow-wave structure with integrated graphene metamaterial absorber. By utilizing the perfect wave absorption characteristics and good thermal conductivity of graphene metamaterial, a novel planar slow-wave structure loaded with graphene metamaterial absorber is designed. Electromagnetic waves propagate in the microstrip line of the structure, and there is a frequency-selective absorber parallel to the transmission direction of the electromagnetic wave below. The designed planar slow-wave structure with integrated graphene metamaterial absorber conforms to the development trend of miniaturization and integration of traveling wave tubes and has broad application prospects.

[0033] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0034] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "N" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

Claims

1. A planar slow-wave structure with integrated graphene metamaterial absorber, characterized in that: The planar slow-wave structure includes from top to bottom: a zigzag microstrip line, a slow-wave structure dielectric layer, a graphene absorbing pattern layer, a graphene absorbing dielectric layer and a metal bottom plate, wherein two ends of the zigzag microstrip line are respectively connected to a signal input port and a signal output port; the zigzag microstrip line and the slow-wave structure dielectric layer constitute a zigzag line slow-wave structure, and the graphene absorbing pattern layer, the graphene absorbing dielectric layer and the metal bottom plate constitute a planar absorbing structure.

2. The planar slow-wave structure of the integrated graphene metamaterial absorber according to claim 1, characterized in that: The meandering microstrip line is composed of a plurality of metal lines with periodic cross sections of U-shape, V-shape or N-shape arranged at equal intervals.

3. The planar slow-wave structure of the integrated graphene metamaterial absorber according to claim 1, characterized in that: The material of the meandering microstrip line is copper or gold.

4. The planar slow-wave structure of the integrated graphene metamaterial absorber according to claim 1, characterized in that: The material of the slow-wave structure dielectric layer includes quartz, boron nitride, and Rogers plate.

5. The planar slow-wave structure of the integrated graphene metamaterial absorber according to claim 1, characterized in that: The graphene wave absorbing pattern layer is a high conductivity graphene film etched into a resonant ring array structure with complementary openings, and the conductivity of the graphene film is ≥1.1*10 6 S / m.

6. The planar slow-wave structure of the integrated graphene metamaterial absorber according to claim 1, characterized in that: The materials of the graphene absorbing medium layer include quartz and boron nitride.

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