Slow wave structure loaded with wave-absorbing metamaterial and traveling wave tube

Abstract

The invention discloses a slow wave structure loaded with a wave-absorbing metamaterial and a traveling wave tube. The technical field of microwave electronics; comprising a closed metal cavity structure for transmitting electromagnetic waves and a wave-absorbing metamaterial structure loaded on the wall surface of the closed metal cavity structure, the working frequency band of the wave-absorbing metamaterial structure is the non-working mode frequency band of the slow wave structure; according to the scheme, structural improvement is carried out on the basis of a traditional slow wave structure, and non-working mode signals are filtered out by loading the wave-absorbing metamaterial of the non-working mode frequency band in the slow wave structure; the loading of the wave-absorbing metamaterial has no influence on the working mode of the slow wave structure, but absorbs the non-working mode to achieve the filtering effect, thereby achieving the effect of inhibiting mode competition.

Description

Technical Field

[0001] The invention relates to the field of microwave electronic technology, and in particular to a slow-wave structure and a traveling wave tube loaded with a wave-absorbing metamaterial. Background Art

[0002] The traveling wave tube is a crucial microwave electron tube that is widely used in many key areas. In radar systems, whether it is an air defense radar for long-range early warning or an airborne radar for air combat detection, the traveling wave tube can provide high-power signals and significantly improve detection efficiency. In the field of satellite communications, the traveling wave tube, as the core component of the communication satellite transponder, effectively amplifies the signal to ensure the stability and reliability of intercontinental communication transmission. In addition, in electronic warfare, the traveling wave tube can be used by electronic jammers to implement jamming tasks and plays an important role in radar warning receivers. At the same time, it is also widely used in radio and television transmission, amplifying the signal at high power and broadcasting it to achieve widespread dissemination of information.

[0003] In a traveling wave tube, when microwave signals of different modes interact with an electron beam, they compete with each other to obtain the energy of the electron beam. In a traveling wave tube, the electron beam interacts with the microwave field in the slow-wave circuit, which can excite microwave oscillations of multiple modes. These modes compete with each other for the energy of the electron beam, causing the amplitude of some modes to increase while the amplitude of other modes to decrease or be suppressed. Mode competition has a significant negative impact on traveling wave tubes. The simultaneous operation of multiple electromagnetic modes leads to uneven energy distribution. The competing modes consume part of the electron beam energy, weakening the performance of the main mode, thereby reducing the gain and power of the output signal, reducing work efficiency, and may even cause work instability. Summary of the invention

[0004] The technical problem to be solved by the present invention is that: the simultaneous operation of multiple electromagnetic modes leads to uneven energy distribution of the traveling wave tube, the competition mode consumes part of the electron beam energy, weakens the performance of the main mode, thereby reducing the gain and power of the output signal, reducing the working efficiency, and may even cause working instability; the purpose of the present invention is to provide a slow-wave structure and a traveling wave tube loaded with absorbing metamaterials, and the structural improvement is made on the basis of the traditional slow-wave structure. By loading absorbing metamaterials in the non-working mode frequency band in the slow-wave structure, the non-working mode signals are filtered out to suppress mode competition.

[0005] The present invention is achieved through the following technical solutions:

[0006] The present invention provides a slow-wave structure loaded with a wave-absorbing metamaterial, comprising: a closed metal cavity structure for transmitting electromagnetic waves, and a wave-absorbing metamaterial structure loaded on the wall surface of the closed metal cavity structure;

[0007] The operating frequency band of the wave-absorbing metamaterial structure is the non-operating mode frequency band of the slow-wave structure.

[0008] Working principle of this solution: In the traditional slow-wave structure, both the working mode and the non-working mode are transmitted in the beam-wave interaction region. Therefore, when the working mode signal and the electron beam perform beam-wave interaction, the non-working mode will also interact with the electron beam, consuming the energy of the electron beam, weakening the performance of the main mode, thus reducing the gain and power of the output signal and decreasing the working efficiency. This solution provides a slow-wave structure loaded with microwave absorbing metamaterials, which improves the structure based on the traditional slow-wave structure. By loading microwave absorbing metamaterials in the non-working mode frequency band in the slow-wave structure, the non-working mode signal is filtered out to suppress mode competition.

[0009] A further optimized solution is that it also includes a high-pass filter loaded on the wall surface of the slow-wave structure.

[0010] A further optimized solution is that the high-pass filter and the slow-wave structure are loaded to form loading surface A, and the high-pass filter and the microwave absorbing metamaterial structure are loaded to form loading surface B. Among them, the area of loading surface A is smaller than that of loading surface B; loading surface B completely overlaps with the loading wall surface of the high-pass filter.

[0011] A further optimized solution is that the microwave absorbing metamaterial structure includes: a metamaterial array layer, a dielectric layer, and a base layer; the base layer is loaded on the wall surface of the closed metal cavity structure; the dielectric layer covers the wall surface of the base layer, and the metamaterial array layer covers the wall surface of the dielectric layer.

[0012] A further optimized solution is that the working frequency band of the microwave absorbing metamaterial structure is determined by the structure of the metamaterial array layer.

[0013] A further optimized solution is that the metamaterial array layer includes multiple groups of metamaterial elements arranged uniformly. The structures of each group of metamaterial elements are the same, but the sizes are different. The uniform arrangement includes uniformly dividing the dielectric layer into multiple squares with equal areas, and setting a group of metamaterial elements in each square. Each group of metamaterial elements is set at the center of the square.

[0014] A further optimized solution is that the metamaterial element includes: multiple I-shaped units arranged at a spacing of c;

[0015] The length of the "one" part of the I-shaped units arranged at the first and last positions is a, and the width is d; the length of the "one" part of the I-shaped units in the middle position is b, and the width is d; where a > b; the heights of the "|" parts of all I-shaped units are equal, and the widths are equal.

[0016] A further optimized solution is that in different metamaterial elements, the heights of the "|" parts of the I-shaped units are different, and the arrangement spacing between the I-shaped units in all metamaterial elements is c.

[0017] A further optimization scheme is that the material of the metamaterial array layer is metallic copper; the material of the dielectric layer is silicon dioxide; and the material of the substrate layer is metallic copper.

[0018] The present solution also provides a traveling wave tube, comprising the above-mentioned slow-wave structure loaded with absorbing metamaterial.

[0019] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0020] The present invention provides a slow-wave structure and a traveling wave tube loaded with absorbing metamaterials. The structure is improved on the basis of the traditional slow-wave structure. By loading absorbing metamaterials in a non-working mode frequency band in the slow-wave structure, non-working mode signals are filtered out. The loading of the absorbing metamaterial has no effect on the working mode of the slow-wave structure, but absorbs the non-working mode, achieving a filtering effect, thereby achieving an effect of suppressing mode competition. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work. In the drawings:

[0022] Figure 1 Schematic diagram of the slow-wave structure loaded with absorbing metamaterials;

[0023] Figure 2 Schematic diagram of the slow-wave structure principle loaded with absorbing metamaterials;

[0024] Figure 3 It is a schematic diagram of an example structure of a staggered double-gate slow-wave structure;

[0025] Figure 4 It is a top view of the wave-absorbing metamaterial structure;

[0026] Figure 5 Schematic diagram of the absorption rate of the absorbing metamaterial;

[0027] Figure 6 Schematic diagram of the Brillouin curve of the traditional slow-wave structure;

[0028] Figure 7 This is a schematic diagram of the Brillouin curve of the slow-wave structure of this scheme;

[0029] Figure 8 Schematic diagram of field distribution in the working mode of the traditional slow-wave structure;

[0030] Fig. 9This is a schematic diagram of the field distribution of the working mode of the slow-wave structure of this scheme;

[0031] Fig.10 Schematic diagram of field distribution in non-working mode of traditional slow-wave structure;

[0032] Fig.11 This is a schematic diagram of the field distribution of the non-working mode of the slow-wave structure of this scheme;

[0033] Fig.12 This is a comparison diagram of the return wave signal spectrum between the slow-wave structure of this scheme and the traditional slow-wave structure;

[0034] Fig.13 This is a schematic diagram of the filtering results of a traditional high-pass filter;

[0035] Fig.14 This is a schematic diagram of the filtering results of the high-pass filter in this scheme.

[0036] Marks and corresponding parts names in the attached drawings:

[0037] 1-interlaced double-gate slow-wave structure, 2-high-pass filter, 3-wave-absorbing metamaterial structure. DETAILED DESCRIPTION

[0038] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0039] Hereinafter, the term "include" or "may include" used in various embodiments of the present invention indicates the presence of the invented function, operation or element, and does not limit the addition of one or more functions, operations or elements. In addition, as used in various embodiments of the present invention, the terms "include", "have" and their cognates are intended only to indicate specific features, numbers, steps, operations, elements, components or combinations of the foregoing items, and should not be understood as first excluding the presence of one or more other features, numbers, steps, operations, elements, components or combinations of the foregoing items or the possibility of adding one or more features, numbers, steps, operations, elements, components or combinations of the foregoing items.

[0040] The expressions (such as "first", "second", etc.) used in various embodiments of the present invention may modify the various constituent elements in various embodiments, but may not limit the corresponding constituent elements. For example, the above expressions do not limit the order and / or importance of the elements. The above expressions are only used for the purpose of distinguishing an element from other elements. For example, the first user device and the second user device indicate different user devices, although both are user devices. For example, without departing from the scope of various embodiments of the present invention, the first element may be referred to as the second element, and similarly, the second element may also be referred to as the first element.

[0041] The terms used in various embodiments of the present invention are only used for the purpose of describing specific embodiments and are not intended to limit various embodiments of the present invention. As used herein, the singular form is intended to also include the plural form, unless the context clearly indicates otherwise. Unless otherwise limited, all terms used here (including technical terms and scientific terms) have the same meaning as the meaning generally understood by those of ordinary skill in the art to which the various embodiments of the present invention belong. The terms (such as the terms defined in the dictionary generally used) will be interpreted as having the same meaning as the contextual meaning in the relevant technical field and will not be interpreted as having an idealized meaning or an overly formal meaning, unless clearly defined in various embodiments of the present invention.

[0042] The simultaneous operation of multiple electromagnetic modes leads to uneven energy distribution of the traveling wave tube. The competition mode consumes part of the electron beam energy, weakens the performance of the main mode, and thus reduces the gain and power of the output signal, reduces work efficiency, and may even cause work instability. In view of this, the present solution provides the following embodiments to solve the above technical problems.

[0043] Example 1

[0044] This embodiment provides a slow-wave structure loaded with absorbing metamaterials, such as Figure 1 and Figure 2 As shown, it includes: a closed metal cavity structure for transmitting electromagnetic waves, and an absorbing metamaterial structure loaded on the wall surface of the closed metal cavity structure;

[0045] The working frequency band of the wave-absorbing metamaterial structure is the non-working mode frequency band of the slow-wave structure.

[0046] It also includes a high-pass filter loaded on the wall of the slow-wave structure; when the slow-wave structure is in working mode, electromagnetic waves are transmitted in the injection-wave interaction zone, while when the slow-wave structure is in non-working mode, electromagnetic waves are absorbed by the absorbing metamaterial, thereby achieving the effect of suppressing mode competition.

[0047] Further, the slow-wave structure of this embodiment can be any type of slow-wave structure, such as conventional interleaved double-gates, sine waveguides, meander waveguides, helical lines, and other such slow-wave structures. The high-pass filter in this embodiment can employ, but is not limited to, a rectangular waveguide, as long as its cut-off frequency is greater than the operating mode frequency and less than the non-operating mode frequency.

[0048] The high-pass filter and the slow-wave structure are loaded to form loading surface A, and the high-pass filter and the absorbing metamaterial structure are loaded to form loading surface B; wherein, the area of loading surface A is smaller than the area of loading surface B; loading surface B completely overlaps with the loading wall surface of the high-pass filter. The loading surface of the traditional high-pass filter overlaps with the slow-wave structure, that is, the loading wall surface of the high-pass filter is equal to loading surface A, while in this solution, the loading wall surface of the high-pass filter is set to protrude, as Fig.13 and Fig.14 shown. The simulation effect diagram shows that the traditional high-pass filter can only filter out signals above 384 GHz and cannot completely filter out the non-operating mode between 370 GHz and 384 GHz. The improved high-pass filter structure can filter out signals above 337 GHz, and the filtering effect of the improved high-pass filter structure is better.

[0049] In an alternative embodiment, taking the interleaved double-gate slow-wave structure as an example for illustration, as Figure 3 shown, the label 1 in the figure is the interleaved double-gate slow-wave structure, and the label 2 is the high-pass filter. The high-pass filter in this embodiment is a rectangular waveguide. The traditional closed metal wall is replaced by continuously arranged rectangular waveguides on the wide side of the interleaved double-gates. The metal material used for the interleaved double-gate slow-wave structure 1 is highly conductive oxygen-free copper; the absorbing metamaterial structure 3 is loaded on the wall surface of the high-pass filter.

[0050] The absorbing metamaterial structure 3 includes: a metamaterial array layer, a dielectric layer, and a substrate layer; the substrate layer is loaded on the wall surface of the closed metal cavity structure; the dielectric layer covers the wall surface of the substrate layer, and the metamaterial array layer covers the wall surface of the dielectric layer.

[0051] The operating frequency band of the absorbing metamaterial structure is determined by the structure of the metamaterial array layer.

[0052] The metamaterial element includes: a plurality of I-shaped units arranged at a spacing c;

[0053] The "one" part of the I-shaped units arranged at the first and last positions has a length of a and a width of d; the "one" part of the I-shaped units located in the middle position has a length of b and a width of d; wherein, a > b; the heights of the "|" parts of all I-shaped units are equal and the widths are equal.

[0054] The metamaterial array layer includes multiple groups of uniformly arranged metamaterial elements, and the structures of each group of metamaterial elements are the same but the sizes are different.

[0055] Among different metamaterial elements, the height of the "|" part of the I-shaped unit is different, and the arrangement spacing between the I-shaped units in all the metamaterial elements is c.

[0056] A plurality of groups of uniformly arranged metamaterial elements can be understood as evenly dividing the dielectric layer into a plurality of squares with equal areas, and a group of metamaterial elements is arranged in each square, and each group of metamaterial elements is arranged at the center of the square. As Figure 4 shown, the size of the metamaterial array layer in this embodiment is 450um×400um. In the staggered double-gate slow-wave structure and the high-pass filter structure, h = 250um, t = 150um, w = 800um, g = 100um, s = 100um, p = 500um; the metamaterial array layer includes four groups of uniformly arranged metamaterial elements. The first group of metamaterial elements includes 3 I-shaped units arranged at a spacing of c. The length of the "-" part of the I-shaped units arranged at the first and last positions is a = 50um, and the width is d = 20um; the length of the "-" part of the I-shaped unit in the middle position is b = 40um, and the width is d = 20um; the height of the "|" part of all the I-shaped units is equal, e1 = 104um, and the width is equal. The second group of metamaterial elements includes 3 I-shaped units arranged at a spacing of c. The length of the "-" part of the I-shaped units arranged at the first and last positions is a = 50um, and the width is d = 20um; the length of the "-" part of the I-shaped unit in the middle position is b = 40μm, and the width is d = 20um; the height of the "|" part of all the I-shaped units is equal, e2 = 92μm, and the width is equal. The third group of metamaterial elements includes 3 I-shaped units arranged at a spacing of c. The length of the "-" part of the I-shaped units arranged at the first and last positions is a = 50um, and the width is d = 20um; the length of the "-" part of the I-shaped unit in the middle position is b = 40um, and the width is d = 20um; the height of the "|" part of all the I-shaped units is equal, e3 = 85μm, and the width is equal. The fourth group of metamaterial elements includes 3 I-shaped units arranged at a spacing of c. The length of the "-" part of the I-shaped units arranged at the first and last positions is a = 50um, and the width is d = 20um; the length of the "-" part of the I-shaped unit in the middle position is b = 40um, and the width is d = 20um; the height of the "|" part of all the I-shaped units is equal, e4 = 80um, and the width is equal.

[0057] The material of the metamaterial array layer is copper, and the thickness is 1μm;; The material of the dielectric layer is silicon dioxide, and the thickness is 30um; the material of the base layer is copper.

[0058] Embodiment 2

[0059] This embodiment provides a traveling wave tube, including a slow-wave structure loaded with an absorbing metamaterial described in Embodiment 1.

[0060] Example 3

[0061] This embodiment uses CST simulation software to Figure 4 The metamaterial array layer is simulated and the absorption rate of the absorbing metamaterial is calculated as follows: Figure 5 As shown, from Figure 5 It can be seen that the absorption rate of the absorbing metamaterial can reach more than 70% in the frequency band of 370GHz to 440GHz, and the absorption rate in this frequency band exceeds the absorption rate of ceramic materials, which proves that the metamaterial has good absorption rate in a wide bandwidth.

[0062] The Brillouin curves of the traditional staggered double-gate slow-wave structure (traditional slow-wave structure) and the metamaterial-loaded staggered double-gate slow-wave structure (slow-wave structure of this scheme) are shown in Figure 6 and Figure 7 As shown by Figure 6 It can be seen that the frequency band of the non-working mode of the traditional slow-wave structure is 370 GHz to 430 GHz; Figure 7 As shown, the slow-wave structure of this scheme is the metamaterial absorption band in the non-working mode frequency band of 370GHz to 440GHz, which proves that the absorbing frequency band of the absorbing metamaterial can cover the frequency band of the non-working mode.

[0063] The transmission structure of the traditional slow-wave structure and the slow-wave structure of this scheme is calculated using CST simulation software. Figure 8-11 As shown, the working mode can be transmitted in the two comparison structure circuits, while the non-working mode can be transmitted in the traditional interlaced dual-gate slow-wave circuit but cannot be transmitted in the slow-wave structure loaded with metamaterials, proving that the slow-wave structure loaded with metamaterials can effectively absorb the non-working mode.

[0064] CST is used to perform PIC simulation on the slow-wave circuits of the traditional slow-wave structure and the slow-wave structure of this scheme. The Fourier spectrum of the reflected signal is shown in the following figure: Fig.12 As shown, the red color is the reflected signal spectrum of the slow-wave circuit loaded with metamaterials, and the gray color is the reflected signal spectrum of the traditional interlaced double-gate slow-wave circuit. It can be seen from the figure that the spectrum of the slow-wave circuit loaded with metamaterials is purer, proving that the scheme of loading absorbing metamaterials can effectively suppress mode competition.

[0065] This solution loads absorbing metamaterials into the slow-wave structure, which can efficiently absorb the non-working mode while ensuring that the working mode is not affected, reduce the loss of electron beam energy in the non-working mode, optimize the performance of the working mode, and ultimately stabilize the operation of the traveling wave tube and significantly improve the working efficiency.

[0066] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A slow-wave structure loaded with absorbing metamaterial, characterized in that: Comprising: A closed metal cavity structure for transmitting electromagnetic waves, and an absorbing metamaterial structure loaded on the wall surface of the closed metal cavity structure; The operating frequency band of the absorbing metamaterial structure is the non-operating mode frequency band of the slow-wave structure.

2. The slow-wave structure loaded with absorbing metamaterial according to claim 1, characterized in that: It further includes a high-pass filter loaded on the wall surface of the slow-wave structure.

3. The slow-wave structure loaded with absorbing metamaterial according to claim 2, characterized in that: The high-pass filter and the slow-wave structure are loaded to form loading surface A, and the high-pass filter and the absorbing metamaterial structure are loaded to form loading surface B; wherein, the area of loading surface A is smaller than the area of loading surface B; loading surface B completely overlaps with the loading wall surface of the high-pass filter.

4. The slow-wave structure loaded with absorbing metamaterial according to claim 2, characterized in that: The absorbing metamaterial structure includes: a metamaterial array layer, a dielectric layer, and a substrate layer; the substrate layer is loaded on the wall surface of the closed metal cavity structure; the dielectric layer covers the wall surface of the substrate layer, and the metamaterial array layer covers the wall surface of the dielectric layer.

5. The slow-wave structure loaded with absorbing metamaterial according to claim 4, characterized in that: The operating frequency band of the absorbing metamaterial structure is determined by the structure of the metamaterial array layer.

6. The slow-wave structure loaded with absorbing metamaterial according to claim 4, characterized in that: The metamaterial array layer includes multiple groups of metamaterial elements arranged uniformly, and the structures of each group of metamaterial elements are the same, but the sizes are different.

7. The slow-wave structure loaded with absorbing metamaterial according to claim 6, characterized in that: The metamaterial element includes a plurality of I-shaped units arranged at a spacing c; Wherein, the length of the "one" part of the I-shaped units arranged at the first and last positions is a, and the width is d; the length of the "one" part of the I-shaped units located in the middle position is b, and the width is d; wherein, a > b; the heights of the "|" parts of all I-shaped units are equal, and the widths are equal.

8. The slow-wave structure loaded with absorbing metamaterial according to claim 7, characterized in that: In different metamaterial elements, the heights of the "|" parts of the I-shaped units are different, and the arrangement spacing between the I-shaped units in all metamaterial elements is c.

9. The slow-wave structure loaded with absorbing metamaterial according to claim 3, characterized in that: The material of the metamaterial array layer is copper; the material of the dielectric layer is silicon dioxide; the material of the substrate layer is copper.

10. A traveling wave tube, characterized in that: It includes a slow-wave structure loaded with an absorbing metamaterial according to any one of claims 1-9.

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