A slow-wave structure and traveling wave tube loaded with a microwave absorbing metamaterial

Abstract

This invention discloses a slow-wave structure and a traveling-wave tube loaded with a microwave absorbing metamaterial; in the field of microwave electronics; comprising: a closed metal cavity structure for transmitting electromagnetic waves, and a microwave absorbing metamaterial structure loaded on the wall of the closed metal cavity structure; the operating frequency band of the microwave absorbing metamaterial structure is the non-operating mode frequency band of the slow-wave structure; this solution is based on the traditional slow-wave structure and improves the structure by loading a microwave absorbing metamaterial in the non-operating mode frequency band into the slow-wave structure to filter out non-operating mode signals; the loading of the microwave absorbing metamaterial has no effect on the operating mode of the slow-wave structure, but absorbs the non-operating mode, achieving a filtering effect, thereby achieving the effect of suppressing mode competition.

Description

Technical Field

[0001] This invention relates to the field of microwave electronics technology, specifically to a slow-wave structure and traveling-wave tube loaded with microwave-absorbing metamaterials. Background Technology

[0002] Traveling wave tubes (TWTs) are crucial microwave vacuum tubes widely used in numerous key fields. In radar systems, whether for long-range early warning air defense radars or airborne radars for air combat detection, TWTs provide high-power signals, significantly improving detection effectiveness. In satellite communications, TWTs serve as core components of communication satellite transponders, effectively amplifying signals to ensure the stability and reliability of intercontinental communication transmissions. Furthermore, in electronic warfare, TWTs can be used by electronic jammers to carry out jamming missions and play a vital role in radar warning receivers. They are also widely used in broadcast television transmission, amplifying signals at high power for broadcast, enabling the widespread dissemination of information.

[0003] In a traveling wave tube (TWT), different microwave signal modes interact with the electron beam, resulting in a competition among them for energy. In the TWT, the interaction between the electron beam and the microwave field in the slow-wave circuit can excite multiple modes of microwave oscillation. These modes compete for electron beam energy, leading to increased amplitude in some modes and decreased or suppressed amplitude in others. This mode competition has a significant negative impact on the TWT. The simultaneous operation of multiple electromagnetic modes results in uneven energy distribution; competing modes consume some electron beam energy, weakening the performance of the dominant mode, thereby reducing output signal gain and power, decreasing operating efficiency, and potentially even causing operational instability. Summary of the Invention

[0004] The technical problem this invention aims to solve is that the simultaneous operation of multiple electromagnetic modes leads to uneven energy distribution in the traveling wave tube. Competing modes consume some of the electron beam energy, weakening the performance of the main mode, thereby reducing the gain and power of the output signal, reducing operating efficiency, and potentially causing operational instability. The purpose of this invention is to provide a slow-wave structure and traveling wave tube loaded with absorbing metamaterials. Based on the traditional slow-wave structure, structural improvements are made by loading absorbing metamaterials in the non-operating mode frequency band into the slow-wave structure to filter out non-operating mode signals and suppress mode competition.

[0005] This invention is achieved through the following technical solution:

[0006] This solution provides a slow-wave structure loaded with a microwave-absorbing metamaterial, comprising: a closed metal cavity structure for transmitting electromagnetic waves, and a microwave-absorbing metamaterial structure loaded on the wall of the closed metal cavity structure.

[0007] The operating frequency band of the 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, 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 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.

[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 c;

[0015] The length of the "—" part of the I-shaped units arranged at the first and last positions is a, and the width is d; the length of the "—" 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 optimized 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] This solution also provides a traveling wave tube, including the aforementioned slow-wave structure loaded with a wave-absorbing metamaterial.

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

[0020] This invention provides a slow-wave structure and traveling-wave tube with a loaded absorbing metamaterial. Based on the traditional slow-wave structure, structural improvements are made by loading a absorbing metamaterial in the non-operating mode frequency band into the slow-wave structure to filter out non-operating mode signals. The loading of the absorbing metamaterial does not affect the operating mode of the slow-wave structure, but absorbs the non-operating mode, achieving a filtering effect and thus suppressing mode competition. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0022] Figure 1 A schematic diagram of a slow-wave structure loaded with a microwave-absorbing metamaterial;

[0023] Figure 2 A schematic diagram illustrating the principle of a slow-wave structure with a loaded microwave-absorbing metamaterial.

[0024] Figure 3 A schematic diagram of an example of an interleaved dual-grid slow-wave structure;

[0025] Figure 4 Top view of the microwave absorbing metamaterial structure;

[0026] Figure 5 This is a schematic diagram of the absorption rate of the microwave absorbing metamaterial.

[0027] Figure 6 A schematic diagram of the Brillouin curve for a traditional slow-wave structure;

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

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

[0030] Figure 9This is a schematic diagram of the field distribution in the operating mode of the slow-wave structure of this scheme;

[0031] Figure 10 A schematic diagram of the field distribution in the non-operating mode of a traditional slow-wave structure;

[0032] Figure 11 This is a schematic diagram of the field distribution in the non-operating mode of the slow-wave structure in this scheme;

[0033] Figure 12 This is a comparison of the reflected wave signal spectra of the slow-wave structure in this scheme and the traditional slow-wave structure;

[0034] Figure 13 This is a schematic diagram of the filtering result of a traditional high-pass filter;

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

[0036] The attached diagram shows the markings and corresponding component names:

[0037] 1- Interlaced dual-grid slow-wave structure, 2- High-pass filter, 3- Absorbing metamaterial structure. Detailed Implementation

[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 examples and drawings. The exemplary embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0039] In the following, the terms “comprising” or “may include” as used in various embodiments of the invention indicate the presence of an inventive function, operation, or element, and do not limit the addition of one or more functions, operations, or elements. Furthermore, as used in various embodiments of the invention, the terms “comprising,” “having,” and their cognates are intended only to indicate a specific feature, number, step, operation, element, component, or combination of the foregoing, and should not be construed as primarily excluding the presence of one or more other features, numbers, steps, operations, elements, components, or combinations of the foregoing, or the possibility of adding one or more combinations of the foregoing.

[0040] The expressions used in the various embodiments of the present invention (such as "first," "second," etc.) may modify various constituent elements in the various embodiments, but do 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 one element from other elements. For example, a first user device and a second user device refer to different user devices, although both are user devices. For example, a first element may be referred to as a second element without departing from the scope of the various embodiments of the present invention, and similarly, a second element may also be referred to as a first element.

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

[0042] The simultaneous operation of multiple electromagnetic modes leads to uneven energy distribution in the traveling wave tube. The competing modes consume some of the electron beam energy, weakening the performance of the main mode, thereby reducing the gain and power of the output signal, reducing operating efficiency, and may even cause instability. In view of this, this solution provides the following embodiments to solve the above-mentioned technical problems.

[0043] Example 1

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

[0045] The operating frequency band of the absorbing metamaterial structure is the non-operating 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; in the working mode of the slow-wave structure, electromagnetic waves propagate in the beam-wave interaction region, while in the non-working mode of the slow-wave structure, 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, sinusoidal waveguides, meandered waveguides, helical lines, and other such slow-wave structures. The high-pass filter in this embodiment can be, 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 traditional high-pass filter overlaps with the loading surface of 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 protrudes, as Figure 13 and Figure 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 modes 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 optional implementation manner, taking the interleaved double-gate slow-wave structure as an example for illustration, as Figure 3 shown. In the figure, label 1 is the interleaved double-gate slow-wave structure, and 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 length of the "—" part of the I-shaped units arranged at the first and last positions is a, and the width is d; the length of the "—" part of the I-shaped units located in the middle position is b, and the width is d; where a > b; the height and width of the "|" part of all I-shaped units 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 metamaterial elements is c.

[0056] Multiple groups of uniformly arranged metamaterial elements can be understood as evenly dividing the dielectric layer into multiple squares with equal areas, and a group of metamaterial elements is set in each square, and each group of metamaterial elements is set 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 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 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 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 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 utilizes CST simulation software to... Figure 4 Simulations were performed on the metamaterial array layer to calculate the absorption rate of the absorbing metamaterial, such as... Figure 5 As shown, from Figure 5 It can be seen that the absorption rate of this absorbing metamaterial can reach more than 70% in the 370GHz to 440GHz frequency band, which exceeds the absorption rate of ceramic materials in this frequency band, proving that the metamaterial has good absorption rate in a wide bandwidth.

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

[0063] The transmission structures of the traditional slow-wave structure and the slow-wave structure of this scheme were calculated using CST simulation software, such as... Figure 8-11 As shown, the operating mode can be propagated in the two contrast structure circuits, while the non-operating mode can be propagated in the traditional interleaved dual-gate slow-wave circuit, but not in the metamaterial-loaded slow-wave structure, proving that the metamaterial-loaded slow-wave structure can effectively absorb the non-operating mode.

[0064] Using CST, PIC simulations were performed on the slow-wave circuits of the traditional slow-wave structure and the slow-wave structure of this scheme. The Fourier spectrum of their reflected signals is shown below. Figure 12 As shown in the figure, the red part is the reflected signal spectrum of the slow-wave circuit loaded with metamaterials, and the gray part is the reflected signal spectrum of the traditional interleaved dual-gate slow-wave circuit. As can be seen from the figure, the spectrum of the slow-wave circuit loaded with metamaterials is purer, which proves that the metamaterial loading scheme can effectively suppress mode competition.

[0065] This scheme loads absorbing metamaterials into the slow-wave structure, which can efficiently absorb non-operating modes while ensuring that the operating mode is not affected. This reduces the loss of electron beam energy by non-operating modes, optimizes the performance of the operating mode, and ultimately makes the operation of the traveling wave tube more stable and significantly improves its 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 a microwave-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 working frequency band of the absorbing metamaterial structure is the non-working mode frequency band of the slow-wave structure; It further includes a high-pass filter loaded on the wall surface of the slow-wave structure; The high-pass filter and the slow-wave structure are loaded to form a loading surface A, and the high-pass filter and the absorbing metamaterial structure are loaded to form a loading surface B; wherein, the area of the loading surface A is smaller than the area of the loading surface B; the loading surface B completely overlaps with the loading wall surface of the high-pass filter; The slow-wave structure is an interleaved double-gate structure; the interleaved double-gate structure includes a first gate structure, a second gate structure and an interleaved gate structure; the first gate structure is parallel to the second gate structure; the interleaved gate structure is opposite to the first gate structure and the second gate structure; The high-pass filter is a rectangular waveguide, and the high-pass filters are continuously arranged and loaded on the first gate structure, the second gate structure and the interleaved gate structure. The first wall surface of the high-pass filter is loaded with the first gate structure, the second gate structure or the interleaved gate structure, and the absorbing metamaterial structure is loaded on the second wall surface of the high-pass filter; the first wall surface and the second wall surface are opposite surfaces.

2. The slow-wave structure with loaded absorbing metamaterial according to claim 1, 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.

3. The slow-wave structure with loaded absorbing metamaterial according to claim 2, characterized in that, The working frequency band of the absorbing metamaterial structure is determined by the structure of the metamaterial array layer.

4. The slow-wave structure with loaded absorbing metamaterial according to claim 2, characterized in 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.

5. A slow-wave structure loaded with a wave-absorbing metamaterial according to claim 4, characterized in that, The metamaterial element includes a plurality of I-shaped units arranged at a pitch c; Wherein, the length of the "—" part of the I-shaped units arranged at the first and last positions is a, and the width is d; the length of the "—" 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 the I-shaped units are equal, and the widths are equal.

6. A slow-wave structure loaded with a wave-absorbing metamaterial according to claim 5, characterized in that, In different metamaterial elements, the heights of the "|" parts of the I-shaped units are different, and the arrangement pitch between the I-shaped units in all the metamaterial elements is c.

7. A slow-wave structure with a loaded absorbing metamaterial according to claim 2, 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.

8. A traveling wave tube, characterized in that, It includes a slow-wave structure loaded with an absorbing metamaterial according to any one of claims 1-7.

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