Trapezoidal waveguide slow wave structure with trapezoidal top
By setting an isosceles trapezoidal undulation on a trapezoidal waveguide in the terahertz band, the problem of low coupling impedance is solved, and higher output power and gain are achieved, as well as an easy-to-manufacture trapezoidal waveguide slow wave structure.
Patent Information
- Application Number
- CN202511206426.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-27
- Publication Date
- 2025-11-21
AI Technical Summary
The existing slow-wave structures in the terahertz band have low coupling impedance, which affects the performance of terahertz vacuum electronic devices.
A trapezoidal waveguide slow wave structure with a trapezoidal apex is adopted, and the coupling impedance is improved by setting an isosceles trapezoidal undulation on the trapezoidal waveguide.
It enhances the interaction between the electron beam and the electromagnetic field, improves the output power and gain, and has a simple structure that is easy to manufacture, ensuring accuracy.
Smart Images
Figure CN120998758A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of vacuum electron technology, more particularly, it relates to a trapezoidal waveguide slow wave structure with trapezoidal top. BACKGROUND
[0002] Terahertz waves have a wide range of applications in radar, communication, electronic countermeasures and other fields due to their unique properties, and the research of terahertz radiation sources has thus become an important research direction. Traveling wave tubes and backward wave tubes are vacuum electron devices based on the interaction between electron beams and electromagnetic fields, and are one of the main terahertz radiation sources. Traveling wave tubes have the advantages of wide operating bandwidth, high output power, high efficiency, small size, stable and reliable operation, and are widely used in radar, satellite communication, space exploration and scientific experiments, and are particularly suitable for microwave signal applications that require high power and wideband amplification. Backward wave tubes have important applications in continuous wave imaging systems, radio astronomy observation and remote sensing, spectral analysis and material detection in the millimeter wave and terahertz frequency bands due to their wideband tuning characteristics, high output power and electromagnetic interference resistance.
[0003] The slow wave structure, as the core component of the traveling wave tube and the backward wave tube, is the place where the traveling wave tube and the backward wave tube exchange energy, and has an important influence on its performance. In recent years, domestic and foreign researchers have proposed a variety of terahertz slow wave structures, such as zigzag waveguides, staggered double grids, sinusoidal waveguides and their variants. They all have their own advantages, but due to the high loss of terahertz waves, the existing slow wave structures have low coupling impedance. This has become one of the factors restricting the development of terahertz vacuum electron devices.
[0004] Therefore, the present application provides a trapezoidal waveguide slow wave structure with a trapezoidal top to solve the above problems. SUMMARY
[0005] The present application is aimed at the problem of low coupling impedance of existing slow wave structures in the terahertz frequency band, and provides a trapezoidal waveguide slow wave structure with a trapezoidal top, which improves the coupling impedance of the slow wave structure by setting a trapezoidal top on the trapezoidal waveguide.
[0006] The above technical purpose of the present application is achieved by the following technical scheme: including: an upper grid part and a lower grid part disposed on the upper and lower sides, the upper grid part and the lower grid part are both provided with undulating parts periodically and equally spaced along the transmission direction of the electron beam, the undulating parts on the upper and lower sides are oppositely arranged with a half undulating period staggered; the undulating part includes a first trapezoidal part with an isosceles trapezoidal cross section along the transmission direction of the electron beam and a second trapezoidal part with an isosceles trapezoidal cross section perpendicular to the transmission direction of the electron beam, the top surface of the first trapezoidal part is the bottom surface of the second trapezoidal part, and the bottom surface of the first trapezoidal part is arranged on the upper and lower grid parts.
[0007] In a possible implementation, the electron beam channel height satisfies the equation: hb=b-h*2-l*2; wherein hb is the electron beam channel height, b is the cross-sectional narrow side length of the trapezoidal waveguide slow wave structure with a trapezoidal top, h is the periodic fluctuation height of the first trapezoidal part, and l is the height of the second trapezoidal part.
[0008] In a possible implementation, the cross-sectional wide side length a of the trapezoidal waveguide slow wave structure with a trapezoidal top is 0.5 mm, and the cross-sectional narrow side length b of the trapezoidal waveguide slow wave structure with a trapezoidal top is 0.36 mm.
[0009] In a possible implementation, the periodic fluctuation height h of the first trapezoidal part is 0.24 mm, the spacing width w1 between two adjacent isosceles trapezoids in the first trapezoidal part is 0.06 mm, and the fluctuation period length p of the first trapezoidal part is 0.2376 mm.
[0010] In a possible implementation, the height l of the second trapezoidal part is 0.02 mm, and the top surface length w2 of the second trapezoidal part is 0.25 mm.
[0011] In a possible implementation, the electron beam channel height hb is 0.08 mm.
[0012] In a possible implementation, the fluctuation part is formed by milling.
[0013] In a possible implementation, the trapezoidal waveguide slow wave structure with a trapezoidal top is made of an all-metal material.
[0014] In a possible implementation, the trapezoidal waveguide slow wave structure with a trapezoidal top is made of an all-metal material.
[0015] In a possible implementation, the trapezoidal waveguide slow wave structure with a trapezoidal top is made of an all-metal material.
[0016] Compared with the prior art, the present application has the following beneficial effects: by setting a special trapezoidal waveguide, the longitudinal and transverse fluctuation shapes are both isosceles trapezoids; the trapezoidal waveguide with a trapezoidal top has higher electron beam channel center axis coupling impedance and electron beam cross-section average coupling impedance under the same level of normalized phase velocity, the electromagnetic field is more uniformly distributed in the electron beam channel cross-section, the interaction between the electron beam and the electromagnetic field is stronger, and higher output power and gain can be obtained; the trapezoidal waveguide with a trapezoidal top has longitudinal and transverse fluctuation shapes that are both isosceles trapezoids, and the top surface of the trapezoid has a certain width in the longitudinal direction, which avoids the problem that a milling cutter cannot process at the wave peaks and wave troughs of a conventional sinusoidal fluctuation line, and is easier to process than other shapes and easier to ensure precision; in addition, the trapezoidal top structure provides multiple structure parameters such as bottom width, top width, and height, and more ideal electric field distribution can be obtained by adjusting the structure parameters, thereby further enhancing the beam-wave interaction. Attached Figure Description
[0017] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings: Figure 1 A three-dimensional structural diagram of a trapezoidal waveguide slow wave structure with a trapezoidal top provided in an embodiment of this application; Figure 2 A front view of a trapezoidal waveguide slow-wave structure with a trapezoidal top provided in an embodiment of this application; Figure 3 A side view of a trapezoidal waveguide slow-wave structure with a trapezoidal top provided in an embodiment of this application; Figure 4 A three-dimensional structural diagram of an existing cosine gate-loaded sinusoidal waveguide slow-wave structure provided in the embodiments of this application; Figure 5 A three-dimensional structural diagram of an existing trapezoidal waveguide slow wave structure provided in the embodiments of this application; Figure 6 A comparison diagram of the dispersion characteristics of a trapezoidal waveguide with a trapezoidal top, a cosine grating-loaded sinusoidal waveguide, and a trapezoidal waveguide provided for embodiments of this application; Figure 7 A comparison diagram of the central axis coupling impedance of the electron beam channel of a trapezoidal waveguide with a trapezoidal top, a cosine-grating-loaded sinusoidal waveguide, and a trapezoidal waveguide provided for embodiments of this application; Figure 8 A comparison diagram of the average coupling impedance of the electron beam channel cross section of a trapezoidal waveguide with a trapezoidal top, a cosine-grating-loaded sinusoidal waveguide, and a trapezoidal waveguide provided for embodiments of this application; Figure 9 A high-frequency transmission characteristic diagram of a trapezoidal waveguide with a trapezoidal top provided for an embodiment of this application. Detailed Implementation
[0018] In the following, the terms “comprising” or “may include” as used in the various embodiments of this application indicate the presence of the claimed function, operation, or element, and do not limit the addition of one or more functions, operations, or elements. Furthermore, as used in the various embodiments of this application, 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.
[0019] The expressions used in the various embodiments of the present application, such as "first", "second", etc., can modify various constituent elements in the various embodiments, but can 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 for the purpose of distinguishing one 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 the various embodiments of the present application, a first element can be referred to as a second element, and likewise, a second element can be referred to as a first element.
[0020] The terms used in the various embodiments of the present application are only for the purpose of describing specific embodiments and are not intended to limit the various embodiments of the present application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly dictates otherwise. Unless otherwise defined, all terms used herein, including technical terms 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 present application belong. The terms such as those defined in a generally used dictionary will be interpreted to have the same meaning as the contextual meaning in the relevant technical field and will not be interpreted to have an idealized or overly formal meaning, unless clearly defined in the various embodiments of the present application.
[0021] To make the purposes, technical solutions and advantages of the present application clearer, further detailed description of the present application is made below in conjunction with embodiments and drawings, the illustrative embodiments of the present application and the description thereof are only for the purpose of explaining the present application and do not limit the present application.
[0022] Please refer to Figure 1 shown, Figure 1 A three-dimensional structure diagram of a trapezoidal waveguide slow wave structure with a trapezoidal top is provided for embodiments of the present application. The trapezoidal waveguide slow wave structure with a trapezoidal top includes an upper gate portion and a lower gate portion disposed on the upper and lower sides, respectively. The upper gate portion and the lower gate portion are both provided with undulating portions periodically and equally spaced in the direction of electron beam transmission. The undulating portions on the upper and lower sides are oppositely arranged with a half undulating period offset. The undulating portions include a first trapezoidal portion with an isosceles trapezoidal cross section in the direction of electron beam transmission and a second trapezoidal portion with an isosceles trapezoidal cross section perpendicular to the direction of electron beam transmission. The top surface of the first trapezoidal portion is the bottom surface of the second trapezoidal portion, and the bottom surface of the first trapezoidal portion is disposed on the upper and lower gate portions.
[0023] Specifically, as Figures 1-3As shown, the trapezoidal waveguide slow wave structure with trapezoidal top (referred to as trapezoidal top trapezoidal waveguide) has a cross-sectional wide edge length a and a cross-sectional narrow edge length b. The upper and lower sides of the trapezoidal top trapezoidal waveguide are periodically undulated in the longitudinal direction (i.e., the electron beam transmission direction) in the shape of an isosceles trapezoid. Adjacent two isosceles trapezoids are separated by a flat plate structure to form a first trapezoidal part. Starting from the electron beam input port, the periodic undulation height of the first trapezoidal part is h, the spacing width between adjacent two isosceles trapezoids in the first trapezoidal part is w1, and the undulation period length of the first trapezoidal part is p. The electron beam channel is between the periodic undulations of the upper and lower sides of the first trapezoidal part, and the width of the natural electron beam channel is the cross-sectional wide edge length a of the trapezoidal waveguide. The top surface of the first trapezoidal part close to the electron beam channel is also undulated in the transverse direction (i.e., the wide edge direction) to form an isosceles trapezoid, thereby obtaining a second trapezoidal part. The height of the second trapezoidal part is l, the length of the top surface of the second trapezoidal part is w2, the length of the bottom surface of the second trapezoidal part (i.e., the transverse width) is a, and the longitudinal thickness of the second trapezoidal part is w1. The spacing between the upper and lower sides of the second trapezoidal part along the narrow edge direction, i.e., the height of the electron beam channel, is hb.
[0024] The principle of the present application is that the trapezoidal top trapezoidal waveguide reduces the phase velocity of electromagnetic waves by the trapezoidal periodic structure of the first trapezoidal part, realizes synchronization of the phase velocity of electromagnetic waves and the speed of the electron beam, enhances the beam-wave interaction, thereby improving the coupling impedance and output power. The second trapezoidal part (referred to as trapezoidal top) forms a local enhanced electric field concentration area on the top surface of the trapezoidal top, i.e., the electric field is more concentrated near the top surface and the inclined surface of the trapezoidal top, thereby enhancing the longitudinal electric field strength near the electron beam channel.
[0025] The improvement of the present application is that by setting a special trapezoidal waveguide, the undulation shapes in the longitudinal and transverse directions are both isosceles trapezoids. The trapezoidal top trapezoidal waveguide has higher electron beam channel central axis coupling impedance and electron beam cross-section average coupling impedance under the same level of normalized phase velocity, the electromagnetic field is more uniformly distributed in the electron beam channel cross-section, the interaction between the electron beam and the electromagnetic field is stronger, and higher output power and gain can be obtained. The undulation shapes of the trapezoidal top trapezoidal waveguide in the longitudinal and transverse directions are both isosceles trapezoids, which is simpler in structure. The top surface of the trapezoidal top has a certain width in the longitudinal direction, which avoids the problem that the milling cutter cannot process at the wave peak and wave valley of the conventional sinusoidal undulation line, and is easier to process than other shapes and easier to ensure precision. In addition, the trapezoidal top structure provides multiple structural parameters such as bottom width, top width, and height, which can be adjusted to optimize the electric field distribution and further enhance the beam-wave interaction.
[0026] Furthermore, the structural parameters of the trapezoidal waveguide slow wave structure are designed to optimize and adjust the phase velocity and field distribution of the electromagnetic wave propagating therein, so as to have more sufficient beam-wave interaction with the electron beam, thereby improving the coupling impedance and output power.
[0027] In a possible implementation, the electron beam channel height satisfies the equation: hb=b-h×2-l×2; where hb is the electron beam channel height, b is the length of the narrow side of the cross section of the trapezoidal top trapezoidal waveguide, h is the periodic fluctuation height of the first trapezoidal part, and l is the height of the second trapezoidal part.
[0028] In a possible implementation, the structural dimensions are selected as: a=0.5mm, b=0.36mm; where a is the length of the wide side of the cross section of the trapezoidal top trapezoidal waveguide, and b is the length of the narrow side of the cross section of the trapezoidal top trapezoidal waveguide.
[0029] Further, h=0.24mm, w1=0.06mm, p=0.2376mm; where h is the periodic fluctuation height of the first trapezoidal part, w1 is the spacing width of two adjacent isosceles trapezoids in the first trapezoidal part, and p is the fluctuation period length of the first trapezoidal part.
[0030] Further, l=0.02mm, w2=0.25mm; where l is the height of the second trapezoidal part, and w2 is the length of the top surface of the second trapezoidal part.
[0031] Further, hb=0.08mm; where hb is the electron beam channel height.
[0032] Specifically, by setting the above structural parameters, the trapezoidal waveguide slow wave structure with a trapezoidal top can be applied to the 340GHz frequency band.
[0033] In a possible implementation, the fluctuation part is formed by milling.
[0034] In a possible implementation, the trapezoidal waveguide slow wave structure with a trapezoidal top is made of an all-metal material.
[0035] Specifically, the trapezoidal waveguide slow wave structure is of an all-metal structure, and the machining material can use copper or other metals. The mechanical machining, milling, and other metal machining processes are used, the overall structure is simple and easy to process, and the machining difficulty of the curved fluctuation can be effectively avoided.
[0036] A traveling wave tube includes a trapezoidal waveguide slow wave structure with a trapezoidal top as shown in Figure 1 .
[0037] A backward wave tube includes a trapezoidal waveguide slow wave structure with a trapezoidal top as shown in Figure 1 .
[0038] It can be understood that, Figure 1 the slow wave structure as shown in is applied to the slow wave structure of the traveling wave tube and the backward wave tube, as the place for energy exchange between the electromagnetic field and the electron beam of the traveling wave tube and the backward wave tube, and mainly works in the millimeter wave terahertz frequency band.
[0039] Please see Figures 4-5 As shown, embodiments of this application also provide comparative structures to verify the effectiveness of the trapezoidal waveguide slow wave structure with trapezoidal top provided in this application.
[0040] Figure 4 A three-dimensional structural diagram of an existing cosine-grating-loaded sinusoidal waveguide slow-wave structure provided in this application embodiment. Figure 4 It can be seen that the comparative cosine grating loaded sinusoidal waveguide includes a flat-top sinusoidal waveguide, and the clipped part has a periodic cosine undulation in the wide side direction to form a cosine grating. The minimum vertical distance between the upper and lower cosine gratings is the height of the electron beam channel.
[0041] Figure 5 A three-dimensional structural diagram of an existing trapezoidal waveguide slow-wave structure provided for embodiments of this application. Figure 5 It can be seen that the comparative trapezoidal waveguide includes a trapezoidal waveguide with periodic undulations in the shape of an isosceles trapezoidal line, and the minimum vertical distance between the upper and lower trapezoidal waveguides is the height of the electron beam channel.
[0042] Please see Figures 6-9 As shown, for the slow wave structure (trapezoidal waveguide with trapezoidal top) provided in this application and the two comparative structures mentioned above (cosine grating loaded sinusoidal waveguide and trapezoidal waveguide), a comparison diagram of dispersion characteristics, a comparison diagram of coupling impedance of the central axis of the electron beam channel, a comparison diagram of average coupling impedance of the cross section of the electron beam channel, and a high-frequency transmission characteristic diagram are drawn to illustrate the improvement effect.
[0043] Figure 6 A comparison diagram of the dispersion characteristics of a trapezoidal waveguide with a trapezoidal apex, a cosine-grating-loaded sinusoidal waveguide, and a trapezoidal waveguide provided in the embodiments of this application. Figure 6 As can be seen, in this embodiment, the dispersion characteristics of the three slow-wave structures are basically at the same level. Among them, the dispersion characteristics of the trapezoidal waveguide with the trapezoidal top and the comparative trapezoidal waveguide are flatter.
[0044] Figure 7 , 8 A comparison diagram of the central axis coupling impedance and average cross-sectional coupling impedance of the electron beam channel for a trapezoidal waveguide with a trapezoidal apex, a cosine-grating-loaded sinusoidal waveguide, and a trapezoidal waveguide, provided for embodiments of this application. Figure 7 , 8It can be seen that in the embodiment, the center axis coupling impedance and the electron beam channel cross section average coupling impedance of the trapezoidal waveguide with trapezoidal top of the application are higher than those of the other two slow wave structures. At the frequency point of 340 GHz, the center axis coupling impedance of the trapezoidal waveguide with trapezoidal top of the application is increased by about 11% compared with the cosine grid loaded sinusoidal waveguide, and by about 25% compared with the trapezoidal waveguide; the electron beam channel cross section average coupling impedance of the trapezoidal waveguide with trapezoidal top of the application is increased by about 47% compared with the cosine grid loaded sinusoidal waveguide, and by about 26% compared with the trapezoidal waveguide. In combination with Figure 5 With the higher coupling impedance of the trapezoidal waveguide with trapezoidal top of the application under the condition that the dispersion characteristics are almost at the same level, it means that the trapezoidal waveguide with trapezoidal top of the application can enhance the interaction between the electron beam and the electromagnetic field, thereby improving the output power and gain of the traveling wave tube and the backward wave tube.
[0045] Figure 9 The high-frequency transmission characteristic diagram of the trapezoidal waveguide with trapezoidal top provided in the embodiment of the application is provided. It can be seen from the diagram that Figure 9 It can be seen that in the embodiment, the trapezoidal waveguide with trapezoidal top of the application has lower reflection parameters and transmission loss in the frequency range of 320-380 GHz, and has good transmission performance.
[0046] In summary, the trapezoidal waveguide with trapezoidal top provided in the application can enhance the longitudinal electric field intensity of the interaction region, enhance the degree of beam-wave interaction, thereby improve the coupling impedance of the structure and increase the output power; the trapezoidal top has many adjustable parameters and is easy to optimize, and the structure is simple, which is convenient for ensuring the machining precision.
[0047] The above specific embodiments further illustrate the purpose, technical solutions and advantages of the application. It should be understood that the above description is only a specific embodiment of the application and is not used to limit the protection scope of the application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application should be included in the protection scope of the application.
Claims
1. A trapezoidal waveguide slow wave structure with a trapezoidal top, characterized in that, The application relates to a trapezoidal waveguide slow wave structure with a trapezoidal top. The upper and lower trapezoidal waveguide slow wave structures are provided with fluctuation parts which are periodically and equidistantly arranged along the transmission direction of the electron beam, and the fluctuation parts on the upper and lower sides are oppositely arranged with a half fluctuation period. The fluctuation part comprises a first trapezoidal part with an isosceles trapezoidal cross section along the transmission direction of the electron beam and a second trapezoidal part with an isosceles trapezoidal cross section along the direction perpendicular to the transmission direction of the electron beam, the top surface of the first trapezoidal part is the bottom surface of the second trapezoidal part, and the bottom surface of the first trapezoidal part is arranged on the upper and lower trapezoidal waveguide slow wave structures.
2. The trapezoidal waveguide slow wave structure with trapezoidal top of claim 1, wherein, The electron beam channel height satisfies the equation hb=b-h*2-l*2, wherein hb is the electron beam channel height, b is the cross section narrow side length of the trapezoidal waveguide slow wave structure with a trapezoidal top, h is the periodic fluctuation height of the first trapezoidal part, and l is the height of the second trapezoidal part.
3. The trapezoidal waveguide slow wave structure with trapezoidal top of claim 1, wherein, The cross section wide side length a of the trapezoidal waveguide slow wave structure with a trapezoidal top is 0.5 mm, and the cross section narrow side length b of the trapezoidal waveguide slow wave structure with a trapezoidal top is 0.36 mm.
4. A trapezoidal waveguide slow wave structure with trapezoidal top according to claim 3, characterized in that, The periodic fluctuation height h of the first trapezoidal part is 0.24 mm, the spacing width w1 of two adjacent isosceles trapezoids in the first trapezoidal part is 0.06 mm, and the fluctuation period length p of the first trapezoidal part is 0.2376 mm.
5. A trapezoidal waveguide slow wave structure with trapezoidal top according to claim 4, characterized in that, The height l of the second trapezoidal part is 0.02 mm, and the top surface length w2 of the second trapezoidal part is 0.25 mm.
6. A trapezoidal waveguide slow wave structure with trapezoidal top according to claim 5, characterized in that, The electron beam channel height hb is 0.08 mm.
7. The trapezoidal waveguide slow wave structure with trapezoidal top of claim 1, wherein, The fluctuation part is formed by milling.
8. The trapezoidal waveguide slow wave structure with trapezoidal top of claim 1, wherein, The trapezoidal waveguide slow wave structure with a trapezoidal top is made of full metal materials.
9. A traveling wave tube, characterized by, The application relates to a trapezoidal waveguide slow wave structure with a trapezoidal top.
10. A backward wave tube, characterized by The application relates to a trapezoidal waveguide slow wave structure with a trapezoidal top.