A traveling wave tube and its segmented staggered double-grid slow-wave structure

Abstract

The present invention discloses a traveling wave tube and a segmented staggered double-grid slow-wave structure thereof, and the present invention belongs to the field of microwave electronics and electric vacuum technology. The slow-wave structure of the present invention includes a rectangular waveguide, and also includes two rows of segmented metal grids staggeredly loaded on the inner wall of the rectangular waveguide; the segmented metal grids sequentially include a first rectangular segment, an isosceles trapezoidal segment, and a second rectangular segment. The present invention modifies the shape of the sinusoidal metal grid on the basis of the traditional sinusoidal waveguide slow-wave structure. On the one hand, a rectangular structure is introduced at the crest and trough of the sinusoidal line, and on the other hand, the sinusoidal line between the rectangular structures is changed into a straight line, so that the structure retains the characteristic that the cross-sectional dimensions of the sinusoidal waveguide slow-wave structure are equal everywhere, thereby also having low reflection and low ohmic loss. At the same time, the added rectangular structure reduces the distance between the upper and lower metal grid vertices, thereby increasing the longitudinal electric field strength in the electron beam channel, and can obtain a higher coupling impedance.

Description

Technical Field

[0001] The invention belongs to the field of microwave electronics and electric vacuum technology, and in particular relates to a segmented staggered double-grid slow-wave structure applied to a traveling wave tube. Background Art

[0002] As an emerging research discipline in the field of electronic science, terahertz technology has broad application prospects in the fields of communications, medical imaging and security. In the field of terahertz technology, how to generate terahertz waves is a very critical issue. Vacuum electronic devices are currently one of the most effective technologies for broadband high-power terahertz signal sources and amplifiers, and traveling wave tubes are the most widely used broadband high-power amplifiers among many vacuum electronic devices. As a key component of the traveling wave tube, the slow-wave structure largely determines the performance of the traveling wave tube. However, with the increase of operating frequency, the reduction of structural size caused by the co-occurrence effect, the increase of metal loss caused by the skin effect, and the reduction of coupling impedance have become the main problems facing the current terahertz slow-wave structure.

[0003] At present, the slow-wave structures studied in TWTs in the terahertz band mainly include folded waveguides, rectangular staggered double gratings, and sinusoidal waveguides. Among them, the sinusoidal waveguide slow-wave structure is widely used in the research of TWTs of terahertz waveguides due to its low reflection and ohmic loss characteristics.

[0004] The traditional sinusoidal waveguide slow-wave structure consists of a rectangular waveguide and two rows of sinusoidal metal grids staggered on the inner wall of the waveguide. It has the characteristic of equal cross-sectional dimensions everywhere, which is an important source of its low reflection ohmic loss characteristics. However, the setting of the sinusoidal metal grid results in a long distance between the upper and lower metal grid vertices, resulting in a weak longitudinal electric field in its electron beam channel and low coupling impedance, which makes the output power and gain of the sinusoidal waveguide traveling wave tube relatively low. Summary of the invention

[0005] In order to solve the problems of weak longitudinal electric field and low coupling impedance of traditional sinusoidal waveguide slow-wave structures, the present invention provides a traveling wave tube and a segmented staggered double-grid slow-wave structure thereof. The present invention increases the electric field strength in the direction of electromagnetic wave transmission while maintaining the cross-sectional dimensions of the sinusoidal waveguide being equal everywhere, and improves the coupling impedance while having the same loss level as the sinusoidal waveguide.

[0006] The present invention is achieved through the following technical solutions:

[0007] A segmented staggered double-grid slow-wave structure comprises a rectangular waveguide and two rows of segmented metal grids staggeredly loaded on the inner wall of the rectangular waveguide;

[0008] The segmented metal grid includes a first rectangular segment, an isosceles trapezoidal segment and a second rectangular segment in sequence.

[0009] The traditional sinusoidal waveguide slow-wave structure is composed of a rectangular waveguide and two rows of sinusoidal metal grids staggered on the inner wall of the rectangular waveguide. Because the phase of the upper and lower sinusoidal metal grids is staggered at 180 degrees, the size of its cross section is equal everywhere, and it has low reflection and ohmic loss. However, due to the setting of the sinusoidal metal grid, the distance between the upper and lower metal grid vertices is far, resulting in a weak longitudinal electric field in its electron beam channel, which hinders the improvement of coupling impedance. The present invention proposes a segmented staggered double-grid slow-wave structure, which modifies the shape of the sinusoidal metal grid on the basis of the traditional sinusoidal waveguide slow-wave structure. On the one hand, a rectangular structure is introduced at the peak and trough of the sinusoidal line, and on the other hand, the sinusoidal line between the rectangular structures is changed into a straight line, so that the structure retains the characteristics of the sinusoidal waveguide slow-wave structure with equal cross-sectional dimensions everywhere, thereby also having the characteristics of low reflection and low ohmic loss. At the same time, the added rectangular structure reduces the distance between the upper and lower metal grid vertices, thereby increasing the longitudinal electric field strength in the electron beam channel, and can obtain a higher coupling impedance, effectively improving the output power, gain and electronic efficiency of the traveling wave tube.

[0010] As a preferred embodiment, the height of the first rectangular segment of the present invention is h1 and the width is s;

[0011] The upper base of the isosceles trapezoidal segment is s, the lower base is ps, and the height is h;

[0012] The height of the second rectangular segment is h1, and the width is ps;

[0013] Where p is the period length of the slow-wave structure.

[0014] As a preferred embodiment, the upper and lower rows of segmented metal grids of the present invention and the inner wall of the wide side of the metal waveguide form an electromagnetic wave channel.

[0015] As a preferred embodiment, the cross section of the electromagnetic wave channel of the present invention is a rectangle with a width of w and a height of b.

[0016] As a preferred embodiment, the width of the first rectangular segment of the present invention should be less than half of the period length of the slow-wave structure.

[0017] As a preferred embodiment, the cross-sectional dimensions of the slow-wave structure of the present invention are equal everywhere, and it has the characteristics of low reflection and low ohmic loss.

[0018] As a preferred embodiment, the slow-wave structure of the present invention increases the longitudinal electric field strength in the electron beam channel and improves the coupling impedance.

[0019] On the other hand, the present invention provides a traveling wave tube, comprising the above-mentioned segmented staggered grating slow-wave structure of the present invention.

[0020] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0021] The segmented staggered double-grid slow-wave structure proposed in the present invention introduces a rectangular structure on the basis of the traditional sinusoidal waveguide slow-wave structure and changes the sinusoidal line into a straight line, so that the cross-sectional dimensions of the sinusoidal waveguide are kept equal everywhere while increasing the longitudinal electric field strength in the electron injection channel, thereby having a higher coupling impedance while having the same loss level as the sinusoidal waveguide, and can effectively improve the output power, gain and electronic efficiency of the traveling wave tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0023] Figure 1 This is a three-dimensional schematic diagram of the traditional sinusoidal waveguide slow-wave structure.

[0024] Figure 2 It is a three-dimensional schematic diagram of a segmented staggered double-gate slow-wave structure according to an embodiment of the present invention.

[0025] Figure 3 It is a cross-sectional view of a segmented staggered double-gate slow-wave structure according to an embodiment of the present invention.

[0026] Figure 4 It is a comparison diagram of dispersion curves of the segmented staggered double-gate slow-wave structure of an embodiment of the present invention and the traditional sinusoidal waveguide slow-wave structure.

[0027] Figure 5 3 is a comparison diagram of the coupling impedance between the segmented staggered dual-gate slow-wave structure of an embodiment of the present invention and the traditional sinusoidal waveguide slow-wave structure.

[0028] Figure 6 This is a comparison diagram of the attenuation constants of the segmented staggered dual-gate slow-wave structure of an embodiment of the present invention and the traditional sinusoidal waveguide slow-wave structure.

[0029] Reference numerals and corresponding component names:

[0030] 1- rectangular waveguide, 2- sinusoidal metal grid, 3- segmented metal grid, 31- first rectangular segment, 32- isosceles trapezoidal segment, 33- second rectangular segment, 4- electromagnetic wave channel. DETAILED DESCRIPTION

[0031] 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.

[0032] In various embodiments of the present invention, the expression "or" or "at least one of A or / and B" includes any combination or all combinations of the words listed at the same time. For example, the expression "A or B" or "at least one of A or / and B" may include A, may include B, or may include both A and B.

[0033] 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.

[0034] It should be noted that if it is described that one component element is “connected” to another component element, the first component element may be directly connected to the second component element, and a third component element may be “connected” between the first component element and the second component element. Conversely, when one component element is “directly connected” to another component element, it can be understood that there is no third component element between the first component element and the second component element.

[0035] 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.

[0036] 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.

[0037] Example 1

[0038] like Figure 1 As shown, the traditional sinusoidal waveguide slow-wave structure consists of a rectangular waveguide 1 and two rows of sinusoidal metal grids 2 staggered on the inner wall of the waveguide. Because the phase of the upper and lower sinusoidal grids is staggered at 180 degrees, the size of its cross section is equal everywhere, and it has lower reflection and ohmic loss. However, due to the setting of the sinusoidal metal grid, the distance between the upper and lower metal grid vertices is far, resulting in a weak longitudinal electric field in its electron beam channel, which hinders the improvement of coupling impedance. Based on this, this embodiment proposes a segmented staggered double-grid slow-wave structure.

[0039] Specific as Figure 2-Figure 3 As shown, the segmented staggered double-gate slow-wave structure proposed in this embodiment is composed of a rectangular waveguide 1 and two upper and lower rows of segmented metal gates 3 staggeredly loaded on the inner wall of the rectangular waveguide 1, and the segmented metal gate 3 can be divided into three sections: a first rectangular section 31 with a height of h1 and a width of s, an isosceles trapezoidal section 32 with an upper base of s, a lower base of ps and a height of h, and a second rectangular section 33 with a height of h1 and a width of ps, wherein p is the period length of the slow-wave structure.

[0040] The cross section of the electromagnetic wave channel 4 formed by the upper and lower metal grids 3 and the inner wall of the wide side of the rectangular waveguide is equal everywhere, and the cross section is a rectangle with a width of w and a height of b.

[0041] The segmented staggered double-grid slow-wave structure proposed in the present embodiment modifies the shape of the sinusoidal metal grid on the basis of the traditional sinusoidal waveguide slow-wave structure. First, the same rectangular structure is introduced at the peaks and troughs of the sinusoidal line, and then the sinusoidal shape in the middle of the rectangular structure is changed to a straight line to obtain the above-mentioned segmented staggered double-grid slow-wave structure. This structure retains the characteristic of the sinusoidal waveguide having equal cross-sectional dimensions everywhere, and thus also has the characteristics of low reflection and low ohmic loss. At the same time, the added rectangular structure reduces the distance between the upper and lower metal grid vertices, thereby increasing the longitudinal electric field strength in the electron beam channel. Therefore, the segmented staggered double-grid slow-wave structure proposed in the present embodiment has higher coupling impedance, and can effectively improve the output power, gain and electronic efficiency of the traveling wave tube.

[0042] In an optional implementation manner, the width s of the first rectangular segment 31 should be smaller than half of the period length p of the slow-wave structure.

[0043] Example 2

[0044] This embodiment uses three-dimensional electromagnetic simulation software to simulate the segmented staggered double-gate slow-wave structure and the traditional sinusoidal waveguide slow-wave structure proposed in the above embodiment 1.

[0045] Among them, Figure 2-3 As shown, the structure of the segmented staggered double-grid slow-wave structure, w is the width of the slow-wave structure, h is the height of the isosceles trapezoidal part of the segmented metal gate, h1 is the height of the upper rectangular and lower rectangular parts of the segmented metal gate, s is the width of the upper rectangular part of the metal gate, b is the height of the electromagnetic wave channel formed by the upper and lower metal gates, and p is the period length of the structure. The structural dimensions of the segmented staggered double-grid slow-wave structure used in this embodiment are (unit: μm):

[0046] w=490, h=260, h1=50, s=60, b=360, p=282.

[0047] like Figure 1 As shown, the traditional sinusoidal waveguide slow-wave structure, w is the width of the slow-wave structure, h is the height of the sinusoidal grating, b is the height of the electromagnetic wave channel formed by the upper and lower sinusoidal gratings, and p is the period length of the structure. The structural dimensions of the traditional sinusoidal waveguide slow-wave structure used in this embodiment are (unit: μm):

[0048] w=490h=270, b=370, p=280.

[0049] The segmented staggered double-gate slow-wave structure and the traditional sinusoidal waveguide slow-wave structure were simulated using the three-dimensional electromagnetic simulation software HFSS, and the dispersion characteristics, coupling impedance and time consumption of the two slow-wave structures were compared and analyzed. The results are as follows: Figure 4-Figure 6 As shown. Among them, Figure 4 The dispersion characteristic curve (normalized phase velocity versus frequency) of this embodiment is compared with that of the traditional sinusoidal waveguide slow wave structure. Figure 5 The comparison of the coupling impedance of this embodiment and the traditional sinusoidal waveguide slow wave structure with the frequency is shown in FIG. Figure 6 The figure is a comparison of the variation of the attenuation constant of this embodiment with that of the traditional sinusoidal waveguide slow-wave structure with frequency.

[0050] Depend on Figure 4 It can be obtained that the dispersion characteristics of the segmented staggered double-grid slow-wave structure proposed in the embodiment of the present invention are basically the same as those of the traditional sinusoidal waveguide slow-wave structure, and the normalized phase velocities of the two structures are basically the same in the frequency range of 306-430GHz, ensuring that the working environment of the two slow-wave structures is consistent. In addition, the working bandwidth of the segmented staggered double-grid slow-wave structure is slightly increased compared with the traditional sinusoidal waveguide slow-wave structure.

[0051] On this basis, Figure 5It can be obtained that, under basically the same dispersion, the segmented staggered double-gate slow-wave structure proposed in the embodiment of the present invention has a higher coupling impedance than the traditional sinusoidal waveguide slow-wave structure in the entire operating frequency band, and at the typical frequency of 340 GHz, the coupling impedance of the segmented staggered double-gate slow-wave structure is improved by 70% compared with the traditional sinusoidal waveguide slow-wave structure.

[0052] Depend on Figure 6 It can be obtained that the loss of the segmented staggered dual-gate slow-wave structure proposed in the embodiment of the present invention is basically consistent with the attenuation constant of the traditional sinusoidal waveguide slow-wave structure, that is, it has the same low-loss characteristics as the traditional sinusoidal waveguide slow-wave structure.

[0053] In summary, it can be concluded that, under the same working conditions, the segmented interleaved dual-gate slow-wave structure proposed in the embodiment of the present invention has a larger coupling impedance than the traditional sinusoidal waveguide slow-wave structure on the basis of having the same low loss as the traditional sinusoidal waveguide slow-wave structure, which is of great significance to the improvement of the output power, gain and electronic efficiency of the traveling wave tube.

[0054] 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 segmented staggered double-gate slow-wave structure, comprising a rectangular waveguide, characterized in that: It also includes two rows of segmented metal grids staggeredly loaded on the inner wall of the rectangular waveguide; The segmented metal grid includes a first rectangular segment, an isosceles trapezoidal segment, and a second rectangular segment in sequence; the first rectangular segment has a height of h1 and a width of s; The upper base of the isosceles trapezoidal segment is s, the lower base is ps, and the height is h; The height of the second rectangular segment is h1, and the width is ps; Where p is the period length of the slow-wave structure; The width of the first rectangular segment should be less than half of the period length of the slow-wave structure; The cross-sectional dimensions of the slow-wave structure are equal everywhere, and it has the characteristics of low reflection and low ohmic loss; The slow-wave structure increases the longitudinal electric field strength in the electron beam channel and improves the coupling impedance.

2. The segmented staggered double-gate slow-wave structure according to claim 1, characterized in that: The upper and lower rows of segmented metal grids and the inner wall of the wide side of the metal waveguide form an electromagnetic wave channel.

3. The segmented staggered double-gate slow-wave structure according to claim 2, characterized in that: The cross section of the electromagnetic wave channel is a rectangle with a width of w and a height of b.

4. A traveling wave tube, characterized in that: It comprises the segmented staggered grating slow-wave structure as described in any one of claims 1-3.

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