Cross-section channel opening type folded waveguide slow wave structure

Abstract

The invention provides a cross-section channel opening type folded waveguide slow-wave structure. The folded waveguide slow-wave structure comprises two first structure parts which are arranged along the broadside direction of the slow-wave structure; the second structure part and the electron beam channel are arranged between the two first structure parts; the first structure part comprises a first straight waveguide section and a first waveguide connection section; the second structure part comprises a second straight waveguide section and a second waveguide connection section; the first waveguide connecting section comprises a second outer arc boundary, a second outer arc connecting part is arranged between the second outer arc boundary and the first straight waveguide section, and a second interval height is formed between the second outer arc connecting part and the axis of the electron beam channel in the radial direction of the electron beam channel; the second waveguide connecting section comprises a third outer arc boundary, a third outer arc connecting part is arranged between the third outer arc boundary and the second straight waveguide section, a third interval height is formed between the third outer arc connecting part and the axis of the electron beam channel in the radial direction of the electron beam channel, and the third interval height is larger than the second interval height.

Description

Technical Field

[0001] The present invention relates to the field of microwave vacuum electronic technology, and more specifically to a cross-section channel opening type folded waveguide slow-wave structure. Background Art

[0002] A traveling wave tube is a vacuum electronic device that can generate or amplify microwave signals and has broad development prospects in the fields of communications, electronic countermeasures, radar systems, etc. The traveling wave tube is mainly composed of an electron gun, a slow-wave structure, a collector, an input and output device, and a magnetic focusing system. Among them, the slow-wave structure is the place for injection-wave interaction, that is, the key component for realizing the generation or amplification of microwave signals. At present, the folded waveguide type slow-wave structure is one of the main slow-wave structures used in traveling wave tubes in the millimeter wave / terahertz frequency band. This structure is an all-metal waveguide structure with the advantages of simple structure, easy processing, and large power capacity. The open-type folded waveguide slow-wave structure with the same working bandwidth has a higher coupling impedance than the conventional folded waveguide slow-wave structure.

[0003] The open-type folded waveguide slow-wave structure is based on the conventional folded waveguide slow-wave structure. The parameter h that controls the height of the straight waveguide is divided into the inner edge height h1 and the outer edge height h2. By adjusting the size of h1, the height of the inner arc of the waveguide is made smaller than the radius rc of the electron injection channel. The electron injection channel between two adjacent straight waveguides opens in the radial direction and is directly connected to the arc part of the waveguide, forming a channel-opening folded waveguide slow-wave structure, such as Figure 1A-Figure 1C In this structure, since the electron beam channel is directly connected to the arc waveguide, the boundary conditions of the electromagnetic field are changed, forming a new field distribution and dispersion characteristics.

[0004] Although the open-type folded waveguide slow-wave structure has a larger coupling impedance than the conventional folded waveguide slow-wave structure, it is still relatively small for millimeter-wave terahertz traveling wave tubes. In order to pursue greater output power and higher efficiency, the coupling impedance of the slow-wave structure needs to be further improved. Summary of the invention

[0005] In view of the above problems, the present invention provides a cross-section channel opening type folded waveguide slow-wave structure to improve the coupling impedance of the slow-wave structure, thereby improving the output power, gain and electronic efficiency of the broadband traveling wave tube.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention provides a cross-section channel opening type folded waveguide slow-wave structure, comprising a multi-periodic structure defined by a plurality of upper grid bodies and a plurality of lower grid bodies that are staggered and distributed with each other;

[0008] The folded waveguide slow-wave structure comprises:

[0009] In one period, two first structure parts are arranged along the wide side direction of the slow-wave structure;

[0010] In one period, a second structure portion is arranged between two first structure portions in the width direction of the slow-wave structure; and

[0011] Electron injection channel;

[0012] The first structural part includes a first straight waveguide section and a first waveguide connecting section which are connected to each other; the second structural part includes a second straight waveguide section and a second waveguide connecting section which are connected to each other;

[0013] The first waveguide connecting section and the second waveguide connecting section both include the same first inner arc boundary, and the first inner arc boundary is located within the boundary defined by the electron injection channel;

[0014] The first waveguide connecting section includes a second outer arc boundary, a second outer arc intersection portion is included between the second outer arc boundary and the first straight waveguide section, and a second spacing height is formed between the second outer arc intersection portion and the axis of the electron injection channel in the radial direction of the electron injection channel;

[0015] The second waveguide connecting section includes a third outer arc boundary, a third outer arc intersection portion is included between the third outer arc boundary and the second straight waveguide section, a third spacing height is formed between the third outer arc intersection portion and the axis of the electron injection channel in the radial direction of the electron injection channel, and the third spacing height is greater than the second spacing height.

[0016] A preferred solution is that a first inner arc intersection portion is included between the first inner arc boundary and the first straight waveguide segment, a first spacing height is formed between the first inner arc intersection portion and the axis of the electron injection channel in the radial direction of the electron injection channel; and the second spacing height is greater than the first spacing height.

[0017] The preferred solution is to define the radius of the electron beam channel as rc, the half-period length of the slow wave structure as p, and the narrow side length of the straight waveguide section as b; the value range of the first interval height is: greater than 0 and less than rc-(pb) / 2; the value of the second interval height is: greater than rc-(p+b) / 2.

[0018] A preferred solution is that, in the radial direction of the electron injection channel, the first inner arc intersection portion is located between the electron injection channel axis and the second outer arc intersection portion, and the second outer arc intersection portion is located between the electron injection channel axis and the third outer arc intersection portion.

[0019] The preferred solution is to define the radius of the electron beam channel as rc, the width length of the slow wave structure as a1, and the width length of the second structure portion as a2; the value range of a2 is: 2rc<a2<a1.

[0020] A preferred solution is that the folded waveguide slow-wave structure is applied to traveling wave tubes in the millimeter wave and terahertz frequency bands.

[0021] The present invention also provides a traveling wave tube, which comprises the folded waveguide slow-wave structure as described above.

[0022] The present invention also provides a method for designing a cross-section channel opening type folded waveguide slow-wave structure, the method comprising:

[0023] Designing an initial folded waveguide slow-wave structure according to needs, the initial folded waveguide slow-wave structure comprises a connected straight waveguide section, a curved waveguide connecting section and an electron injection channel;

[0024] Using three-dimensional electromagnetic field simulation software, the first inner arc boundary is moved downward to within the boundary defined by the electron injection channel;

[0025] Using three-dimensional electromagnetic field simulation software, the third outer arc boundary is moved upward so that a third spacing height formed between the third outer arc intersection and the axis of the electron injection channel in the radial direction of the electron injection channel is greater than a second spacing height formed between the second outer arc intersection and the axis of the electron injection channel in the radial direction of the electron injection channel.

[0026] The preferred solution is that the radius of the electron injection channel is rc, the width length of the slow wave structure is a1, the width length of the second structure portion is a2, and the value range of a2 is: 2rc<a2<a1.

[0027] A preferred solution is to adjust the normalized phase velocity and coupling impedance of the folded waveguide slow-wave structure by changing the second spacing height, the third spacing height and the wide side length of the second structure portion to optimize the performance of the folded waveguide slow-wave structure.

[0028] The beneficial effects of the present invention are:

[0029] Compared with the conventional channel opening type folded waveguide slow-wave structure, the present invention forms a new slow-wave structure by splitting the outer folded waveguide into two first structure parts and a second structure part located between the two first structure parts, and ensuring that the second structure part is higher than the first structure part in the height direction of the slow-wave structure. The cross-section channel opening type folded waveguide slow-wave structure thus obtained is applied to millimeter wave / terahertz traveling wave tubes. Under the premise of the same working frequency band and similar normalized phase velocity within the band, the axial coupling impedance of the electron injection channel can be greatly improved, which can significantly improve the output power, gain efficiency and electronic efficiency of the traveling wave tube.

[0030] In addition, by designing the cross-section of the slow-wave structure into a cross shape, the area of ​​the waveguide circumscribed circle can be reduced while the bandwidth of the folded waveguide slow-wave structure remains unchanged, thereby reducing the actual cross-sectional size of the slow-wave structure, providing space in terms of structural size for improving the focusing performance of the traveling wave tube focusing system.

[0031] The cross-section channel opening type folded waveguide slow-wave structure and traveling wave tube provided by the present invention can be widely used in new generation mobile communication equipment, mobile communication base station equipment in broadband wireless mobile communication technology, and transmitting equipment in the field of satellite transmission and broadcasting and television network. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0033] Figure 1A-Figure 1C It is a schematic diagram of the structure of a conventional channel opening type folded waveguide slow-wave structure.

[0034] Figure 2A-2C It is a schematic diagram of the structure of a conventional folded waveguide slow-wave structure.

[0035] Figure 3A-3C It is a structural schematic diagram of the cross-section channel opening type folded waveguide slow-wave structure of the present invention.

[0036] Figure 4 It is a dispersion characteristic curve diagram of the cross-section channel opening type folded waveguide slow-wave structure of the present invention.

[0037] Figure 5 It is a normalized phase velocity comparison diagram of the cross-section channel opening type folded waveguide slow-wave structure of the present invention, the channel opening type folded waveguide slow-wave structure with similar intra-band phase velocity, and the conventional folded waveguide slow-wave structure.

[0038] Figure 6 It is a comparison diagram of coupling impedances of the cross-section channel opening type folded waveguide slow-wave structure of the present invention, the channel opening type folded waveguide slow-wave structure with similar intra-band phase velocity, and the conventional folded waveguide slow-wave structure.

[0039] Figure 7 It is a normalized phase velocity curve diagram of the cross-section channel opening type folded waveguide slow-wave structure of the present invention under different h2 conditions.

[0040] Figure 8 It is a coupling impedance curve diagram of the cross-section channel opening type folded waveguide slow-wave structure of the present invention under different h2 conditions.

[0041] Fig. 9 It is a normalized phase velocity curve diagram of the cross-section channel opening type folded waveguide slow-wave structure of the present invention under different h3 conditions.

[0042] Fig.10 It is a coupling impedance curve diagram of the cross-section channel opening type folded waveguide slow-wave structure of the present invention under different h3 conditions.

[0043] Fig.11It is a normalized phase velocity curve diagram of the cross-section channel opening type folded waveguide slow-wave structure of the present invention under different a2 conditions.

[0044] Fig.12 It is a coupling impedance curve diagram of the cross-section channel opening type folded waveguide slow-wave structure of the present invention under different a2 conditions. DETAILED DESCRIPTION

[0045] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless otherwise specifically stated.

[0046] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0047] Techniques and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the techniques and equipment should be considered part of the specification.

[0048] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0049] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0050] The invention provides a cross-section channel opening type folded waveguide slow-wave structure, which is applied to traveling wave tubes in millimeter wave and terahertz frequency bands. Figures 1A to 12As shown, specifically, the cross-section channel opening type folded waveguide slow-wave structure includes a multi-periodic structure defined by a plurality of upper grid bodies and a plurality of lower grid bodies that are staggered and distributed with each other; the folded waveguide slow-wave structure includes: two first structure parts 10 arranged along the wide side direction of the slow-wave structure in one period; a second structure part 20 arranged between the two first structure parts 10 in the wide side direction of the slow-wave structure in one period; and an electron injection channel 30; the first structure part 10 includes a first straight waveguide section and a first waveguide connecting section that are connected; the second structure part 20 includes a second straight waveguide section and a second waveguide connecting section that are connected; the first waveguide connecting section and the second waveguide connecting section both include the same first inner arc boundary C 1, the first inner arc boundary C1 is located within the boundary defined by the electron injection channel 30; the first waveguide connecting section includes a second outer arc boundary C2, a second outer arc intersection Q2 is included between the second outer arc boundary C2 and the first straight waveguide section, and a second spacing height h2 is formed between the second outer arc intersection Q2 and the electron injection channel axis L0 in the radial direction of the electron injection channel; the second waveguide connecting section includes a third outer arc boundary C3, a third outer arc intersection Q3 is included between the third outer arc boundary C3 and the second straight waveguide section, and a third spacing height h3 is formed between the third outer arc intersection Q3 and the electron injection channel axis L0 in the radial direction of the electron injection channel, and the third spacing height h3 is greater than the second spacing height h2. The novel folded waveguide slow-wave structure provided by the present invention is based on the channel opening type folded waveguide slow-wave structure, by splitting the waveguide cavity of the folded waveguide into two first structure parts 10 on both sides and a second structure part 20 in the middle, and the second structure part 20 protrudes outward from the first structure part 10, so that the cross section of the slow-wave structure is cross-shaped, forming the cross-section channel opening type folded waveguide slow-wave structure of the present invention. Compared with the channel opening type folded waveguide slow-wave structure and the conventional folded waveguide slow-wave structure, the structure provided by the present invention has a higher axial coupling impedance.

[0051] For traveling wave tubes, the use of a circular inner hole periodic permanent magnet focusing system is a classic electron beam focusing method. For two sets of periodic permanent magnet focusing systems with the same parameters except for the size of the inner hole, the smaller the inner hole, the greater the focusing magnetic field strength, and the stronger the electron beam bunching ability, which is more conducive to improving the performance of the traveling wave tube. For folded waveguide slow wave structures, their radial cross-section is usually circular to match the circular inner hole periodic permanent magnet focusing system. Therefore, the smaller the radial cross-section of the slow wave structure corresponds to the circumscribed circle, the more conducive it is to reduce the inner hole of the focusing system, thereby improving the electron beam bunching effect. At present, the cross-sectional size of the slow wave structure of millimeter wave terahertz traveling wave tubes limits the focusing performance of the electron beam focusing system, making it impossible to further increase the current density, thereby limiting the output power of the traveling wave tube. In order to improve the focusing performance of the electron beam focusing system, it is necessary to further reduce the radial cross-sectional size of the slow wave structure. Compared with the channel opening type folded waveguide slow-wave structure and the conventional folded waveguide slow-wave structure, the structure provided by the present invention has a smaller radial cross-sectional size, the electron injection channel axial direction is the X direction, the wide side direction of the slow-wave structure is the Y direction, and the height direction of the slow-wave structure is the Z direction. The radial cross-section here refers to the cross-section of the slow-wave structure located in the plane formed by the Y direction and the Z direction. The cross-section channel opening type folded waveguide slow-wave structure provided by the present invention can improve the coupling impedance, thereby improving the output power, gain and electronic efficiency of the broadband traveling wave tube, while reducing the radial cross-sectional size of the slow-wave structure to improve the focusing performance of the matching electron injection focusing system.

[0052] In a specific embodiment, a first inner arc intersection portion Q1 is included between the first inner arc boundary C1 and the first straight waveguide segment, and a first spacing height h1 is formed between the first inner arc intersection portion Q1 and the electron injection channel axis L0 in the radial direction of the electron injection channel; the second spacing height h2 is greater than the first spacing height h1.

[0053] Furthermore, the radius of the electron beam channel is rc, the half-period length of the slow wave structure is p, and the narrow side length of the straight waveguide section is b; the value range of the first interval height h1 is: 0

[0054] In a specific embodiment, in the radial direction of the electron injection channel, the first inner arc intersection Q1 is located between the electron injection channel axis L0 and the second outer arc intersection Q2, and the second outer arc intersection Q2 is located between the electron injection channel axis L0 and the third outer arc intersection Q3.

[0055] In a specific embodiment, the radius of the electron injection channel is rc, the width length of the slow-wave structure is a1, the width length of the second structure portion is a2, and the value range of a2 is: 2rc<a2<a1.

[0056] ​The folded waveguide slow-wave structure provided in the embodiment of the present invention is a broadband slow-wave structure; the folded waveguide slow-wave structure is applied to a traveling wave tube in the millimeter wave / terahertz frequency band.

[0057] Specifically, refer to Figure 1A-Figure 1C The figure shows a single-period geometric diagram of a channel-opening folded waveguide slow-wave structure, where a represents the wide side length of the waveguide, b represents the narrow side length of the waveguide, the geometric half-period is p, the straight waveguide height is h, the electron injection channel radius is rc, and the straight waveguide is divided into an inner side height h1 and an outer side height h2. By adjusting the size of h1, the waveguide inner arc height is made smaller than the electron injection channel radius rc, and the electron injection channel between two adjacent straight waveguides opens in the radial direction and is directly connected to the arc portion of the waveguide. The geometric period contains two interaction gaps of unequal lengths.

[0058] The structural dimensions of the specific scheme of the channel-opening folded waveguide slow-wave structure used for comparison are as follows (unit: mm): a=0.870, b=0.160, p=0.260, h1=0.030, h2=0.140, rc=0.120.

[0059] In addition, the circumscribed circle area corresponding to the radial cross section of the channel opening type folded waveguide slow wave structure is: 0.979mm 2 .

[0060] Reference Figure 2A-2C As shown, it is a single-period geometric schematic diagram of a conventional folded waveguide slow-wave structure. In the figure, a represents the wide side length of the waveguide, b represents the narrow side length of the waveguide, the geometric half-period is p, the straight waveguide height is h, and the electron beam channel radius is rc.

[0061] The structural dimensions of the specific scheme of the conventional folded waveguide slow-wave structure used for comparison are as follows (unit: mm): a=0.86, b=0.16, p=0.305, h=0.26, rc=0.12.

[0062] In addition, the circumscribed circle area corresponding to the radial cross section of the conventional folded waveguide slow-wave structure is: 0.994mm 2 .

[0063] Reference Figure 3A-3C The figure shows a single-period geometrical schematic diagram of a cross-section channel opening type folded waveguide slow-wave structure provided by the present invention. The structure is based on the channel opening type folded waveguide slow-wave structure, and the waveguide cavity of the folded waveguide is split into a first structure part 10 and a second structure part 20 to form a new slow-wave structure. Among them, the height of the outer edge of the straight waveguide of the first structure part is h2, and the height of the outer edge of the straight waveguide of the second structure part is h3; the total width of the waveguide is a1, and the width of the second structure part is a2.

[0064] In the G-band region, the specific structural dimensions of the cross-section channel opening type folded waveguide slow-wave structure of the present invention are as follows (unit: mm): a1=0.89, a2=0.52, b=0.16, p=0.26, h1=0.03, h2=0.04, h3=0.22mm, rc=0.12.

[0065] In addition, the radial cross-section of the cross-section channel opening type folded waveguide slow-wave structure corresponds to the circumscribed circle area of ​​0.818 mm 2 , which is 83.55% of the circumscribed circle area of ​​the radial cross section of the channel opening type folded waveguide slow-wave structure and 82.29% of the circumscribed circle area of ​​the radial cross section of the conventional folded waveguide slow-wave structure.

[0066] The cross-section channel opening type folded waveguide slow-wave structure of the present invention, the channel opening type folded waveguide slow-wave structure with similar in-band phase velocity, and the conventional folded waveguide slow-wave structure are simulated using three-dimensional electromagnetic software, and the relevant dispersion characteristics, field distribution, normalized phase velocity, axial coupling impedance and high-frequency loss characteristics are calculated.

[0067] Reference Figure 4 As shown, the dispersion characteristics of the cross-section channel opening type folded waveguide slow-wave structure are shown, and the working point is selected at the -1 spatial harmonic of the eigenmode 3.

[0068] Reference Figure 5 As shown, the normalized phase velocities of the cross-section channel opening type folded waveguide slow-wave structure, the channel opening type folded waveguide slow-wave structure with similar phase velocity in the band, and the conventional folded waveguide slow-wave structure. In the operating frequency band of 200GHz to 230GHz, the maximum difference among the three is less than 0.001.

[0069] Reference Figure 6 As shown, the coupling impedance comparison of the cross-section channel opening type folded waveguide slow-wave structure, the channel opening type folded waveguide slow-wave structure and the conventional folded waveguide slow-wave structure is shown. In the operating frequency band of 200GHz to 230GHz, the axis coupling impedance of the cross-section channel opening type folded waveguide slow-wave structure of the present invention is 3.25% greater than that of the channel opening type folded waveguide slow-wave structure with similar phase velocity in the band, and is 47.82% greater than that of the conventional folded waveguide slow-wave structure.

[0070] Reference Figure 7 The figure shows the normalized phase velocity of the cross-section channel opening type folded waveguide slow-wave structure under different h2. In the operating frequency band of 200GHz to 230GHz, when h2 increases by 0.01mm, the normalized phase velocity decreases by about 0.003.

[0071] Reference Figure 8The figure shows the coupling impedance of the cross-section channel opening type folded waveguide slow-wave structure under different h2. In the operating frequency band of 200GHz to 230GHz, for the low-frequency end (near 200GHz), h2 increases by 0.01mm and the coupling impedance decreases by about 0.2Ω; for the high-frequency end (near 230GHz), h2 has almost no effect on the coupling impedance.

[0072] Reference Fig. 9 The figure shows the normalized phase velocity of the cross-section channel opening type folded waveguide slow-wave structure under different h3. In the operating frequency band of 200 GHz to 230 GHz, for the low-frequency end (near 200 GHz), h3 has almost no effect on the normalized phase velocity; for the high-frequency end (near 230 GHz), h3 increases by 0.01 mm, and the normalized phase velocity decreases by about 0.0006.

[0073] Reference Fig.10 As shown in Figure 1, the coupling impedance of the cross-section channel opening type folded waveguide slow-wave structure under different h3. In the operating frequency band of 200 GHz to 230 GHz, h3 has almost no effect on the coupling impedance.

[0074] Reference Fig.11 The figure shows the normalized phase velocity of the cross-section channel opening type folded waveguide slow-wave structure under different a2. In the operating frequency band of 200GHz to 230GHz, the effect of a2 change on the normalized phase velocity at the low frequency end (near 200GHz) is smaller than that at the high frequency end (near 230GHz). For the low frequency end (near 200GHz), a2 increases by 0.01mm, and the normalized phase velocity decreases by about 0.0003; for the high frequency end (near 230GHz), a2 increases by 0.01mm, and the normalized phase velocity decreases by about 0.0006.

[0075] Reference Fig.12 As shown in Figure 1, the coupling impedance of the cross-section channel opening type folded waveguide slow-wave structure under different a2. In the operating frequency band of 200 GHz to 230 GHz, a2 has almost no effect on the coupling impedance.

[0076] Therefore, the above characteristics can be used to specifically adjust the normalized phase velocity and coupling impedance at each frequency point within the band.

[0077] According to another aspect of the present invention, the present invention further provides a traveling wave tube, which includes the folded waveguide slow-wave structure as described above.

[0078] According to another aspect of the present invention, the present invention also provides a method for designing a cross-section channel opening type folded waveguide slow-wave structure, the method comprising: designing an initial folded waveguide slow-wave structure as needed, the initial folded waveguide slow-wave structure comprising a connected straight waveguide section, a curved waveguide connecting section and an electron injection channel; using three-dimensional electromagnetic field simulation software, moving the first inner arc boundary C1 downward to within the boundary defined by the electron injection channel; using three-dimensional electromagnetic field simulation software, moving the third outer arc boundary C3 upward so that a third spacing height h3 formed between the third outer arc intersection Q3 and the electron injection channel axis L0 in the radial direction of the electron injection channel is greater than a second spacing height h2 formed between the second outer arc intersection Q2 and the electron injection channel axis L0 in the radial direction of the electron injection channel.

[0079] Furthermore, the radius of the electron injection channel is rc, the width length of the slow-wave structure is a1, the width length of the second structure portion is a2, and the value range of a2 is: 2rc<a2<a1.

[0080] Optionally, by changing the second spacing height h2, the third spacing height h3 and the wide side length a2, the normalized phase velocity and coupling impedance of the folded waveguide slow-wave structure are adjusted to optimize the performance of the folded waveguide slow-wave structure, thereby improving the coupling impedance of the slow-wave structure while reducing the radial cross-sectional size of the slow-wave structure, thereby providing space in terms of structural size for improving the focusing performance of the traveling wave tube focusing system.

[0081] More specifically, an initial folded waveguide slow-wave structure is designed as needed, and the initial folded waveguide slow-wave structure includes a connected straight waveguide segment, a curved waveguide connecting segment, and an electron injection channel; using three-dimensional electromagnetic field simulation software, the first inner arc boundary C1 is moved downward to the boundary defined by the electron injection channel to obtain an open-type folded waveguide slow-wave structure; on the basis of the obtained open-type folded waveguide slow-wave structure, the folded waveguide is divided into two first structural parts on both sides and a second structural part in the middle, wherein a second spacing height h2 is designed between a second outer arc boundary C2 of the first structural part and a second outer arc intersection Q2 between the first straight waveguide segment and the axis L0 of the electron injection channel in the radial direction of the electron injection channel; the third outer arc boundary C3 of the second structural part is moved upward, and a third spacing height h3 is designed between a third outer arc intersection Q3 between the third outer arc boundary C3 of the second structural part and the second straight waveguide segment and the axis L0 of the electron injection channel in the radial direction of the electron injection channel, and h3 is greater than h2, thereby achieving improvement in the coupling impedance of the folded waveguide slow-wave structure.

[0082] In summary, compared with the conventional channel opening type folded waveguide slow-wave structure, the present invention forms a new slow-wave structure by splitting the outer folded waveguide into two first structure parts and a second structure part located between the two first structure parts, and ensuring that the second structure part is higher than the first structure part in the height direction of the slow-wave structure. The cross-section channel opening type folded waveguide slow-wave structure thus obtained is applied to millimeter wave / terahertz traveling wave tubes. Under the premise of the same working frequency band and similar normalized phase velocity within the band, the axial coupling impedance of the electron injection channel can be greatly improved, which can significantly improve the output power, gain efficiency and electronic efficiency of the traveling wave tube.

[0083] In addition, by designing the cross-section of the slow-wave structure into a cross shape, the area of ​​the waveguide circumscribed circle can be reduced while the bandwidth of the folded waveguide slow-wave structure remains unchanged, thereby reducing the actual cross-sectional size of the slow-wave structure, providing space in terms of structural size for improving the focusing performance of the traveling wave tube focusing system.

[0084] The cross-section channel opening type folded waveguide slow-wave structure and traveling wave tube provided by the present invention can be widely used in new generation mobile communication equipment, mobile communication base station equipment in broadband wireless mobile communication technology, and transmitting equipment in the field of satellite transmission and broadcasting and television network.

[0085] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A cross-section channel opening type folded waveguide slow-wave structure, characterized in that: A multi-periodic structure is formed by defining a plurality of upper grid bodies and a plurality of lower grid bodies which are staggered and distributed with each other; The folded waveguide slow-wave structure comprises: In one period, two first structure parts are arranged along the wide side direction of the slow-wave structure; In one period, a second structure portion is arranged between two first structure portions in the width direction of the slow-wave structure; and Electron injection channel; The first structural part includes a first straight waveguide section and a first waveguide connecting section which are connected to each other; the second structural part includes a second straight waveguide section and a second waveguide connecting section which are connected to each other; The first waveguide connecting section and the second waveguide connecting section both include the same first inner arc boundary, and the first inner arc boundary is located within the boundary defined by the electron injection channel; The first waveguide connecting section includes a second outer arc boundary, a second outer arc intersection portion is included between the second outer arc boundary and the first straight waveguide section, and a second spacing height is formed between the second outer arc intersection portion and the axis of the electron injection channel in the radial direction of the electron injection channel; The second waveguide connecting section includes a third outer arc boundary, a third outer arc intersection portion is included between the third outer arc boundary and the second straight waveguide section, a third spacing height is formed between the third outer arc intersection portion and the axis of the electron injection channel in the radial direction of the electron injection channel, and the third spacing height is greater than the second spacing height.

2. The cross-section channel opening type folded waveguide slow-wave structure according to claim 1, characterized in that: A first inner arc intersection portion is included between the first inner arc boundary and the first straight waveguide segment, and a first spacing height is formed between the first inner arc intersection portion and the axis of the electron injection channel in the radial direction of the electron injection channel; the second spacing height is greater than the first spacing height.

3. The cross-section channel opening type folded waveguide slow-wave structure according to claim 2, characterized in that: It is defined that the radius of the electron beam channel is rc, the half-period length of the slow wave structure is p, and the narrow side length of the straight waveguide section is b; the value range of the first interval height is: greater than 0 and less than rc-(pb) / 2; the value of the second interval height is: greater than rc-(p+b) / 2.

4. The cross-section channel opening type folded waveguide slow-wave structure according to claim 2, characterized in that: In the radial direction of the electron injection channel, the first inner arc intersection portion is located between the electron injection channel axis and the second outer arc intersection portion, and the second outer arc intersection portion is located between the electron injection channel axis and the third outer arc intersection portion.

5. The cross-section channel opening type folded waveguide slow-wave structure according to claim 1, characterized in that: It is defined that the radius of the electron beam channel is rc, the length of the wide side of the slow-wave structure is a1, and the length of the wide side of the second structure portion is a2; the value range of a2 is: 2rc<a2<a1.

6. The cross-section channel opening type folded waveguide slow-wave structure according to claim 1, characterized in that: The folded waveguide slow-wave structure is applied to traveling wave tubes in millimeter wave and terahertz frequency bands.

7. A traveling wave tube, characterized in that: The traveling wave tube comprises the folded waveguide slow-wave structure as described in any one of claims 1 to 6.

8. A method for designing a cross-section channel opening type folded waveguide slow-wave structure, characterized in that: The method includes: Designing an initial folded waveguide slow-wave structure according to needs, the initial folded waveguide slow-wave structure comprises a connected straight waveguide section, a curved waveguide connecting section and an electron injection channel; Using three-dimensional electromagnetic field simulation software, the first inner arc boundary is moved downward to within the boundary defined by the electron injection channel; Using three-dimensional electromagnetic field simulation software, the third outer arc boundary is moved upward so that a third spacing height formed between the third outer arc intersection and the axis of the electron injection channel in the radial direction of the electron injection channel is greater than a second spacing height formed between the second outer arc intersection and the axis of the electron injection channel in the radial direction of the electron injection channel.

9. The method for designing a folded waveguide slow-wave structure according to claim 8, characterized in that: The radius of the electron injection channel is rc, the width length of the slow wave structure is a1, the width length of the second structure portion is a2, and the value range of a2 is: 2rc<a2<a1.

10. The method for designing a folded waveguide slow-wave structure according to claim 9, characterized in that: By changing the second spacing height, the third spacing height and the wide side length of the second structure portion, the normalized phase velocity and coupling impedance of the folded waveguide slow-wave structure are adjusted to optimize the performance of the folded waveguide slow-wave structure.

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