Groove loading folded waveguide slow wave structure with vertical electronic channel

Abstract

The invention belongs to the technical field of microwave electronics and electric vacuum, and particularly relates to a groove loading folded waveguide slow-wave structure with a vertical electronic channel, which comprises a shell, a slow-wave structure is arranged in the shell, and the slow-wave structure is formed by connecting a series of arc bent waveguides and straight waveguides end to end. The waveguide is equivalent to a folded waveguide formed by bending a rectangular waveguide in a U shape; an expanding groove which penetrates through the straight waveguide part and is self-adaptive along with bending deformation is formed in the middle line of the folded waveguide wall, and the expanding groove of the straight waveguide part is communicated with the folded waveguide cavity to form an electron beam channel. According to the invention, the expansion groove and the folded waveguide are conformally arranged, so that the maximum expansion of the size of an electron beam channel is realized, the electron beam with larger size can be borne, and the working power is improved. A coupling impedance analysis result shows that the folded waveguide slow wave structure has higher coupling impedance and can effectively improve gain and output power.

Description

Technical Field

[0001] The invention belongs to the field of microwave electronics and electric vacuum technology, and in particular relates to a groove-loaded folded waveguide slow-wave structure with a vertical electron channel. Background Art

[0002] With the continuous advancement of science and technology and the rapid development of communications technology, vacuum devices must meet increasingly stringent operating frequency requirements. The terahertz frequency band, with its unique advantages, has demonstrated significant application value in communications, imaging, security inspection, and other fields. In high-speed wireless communications, this frequency band can support transmission rates far exceeding existing frequency bands, providing a technical foundation for the high-speed transmission of massive amounts of data. In the security inspection field, terahertz imaging technology can clearly reveal the fine features of concealed objects, significantly improving the recognition accuracy and operational efficiency of security inspection systems.

[0003] Traditional slow-wave structures achieve the deceleration of the phase velocity of electromagnetic waves through periodic structural design, thereby promoting the effective interaction between electron beams and electromagnetic waves. However, when the application scenarios expand to the terahertz frequency band, the limitations of this structure become increasingly prominent. First, in terms of transmission characteristics, as the frequency increases to the terahertz range, the dielectric loss and conductor loss in the signal transmission process increase significantly, resulting in serious degradation of signal integrity. Secondly, in terms of energy conversion efficiency, limited by the coupling impedance characteristics of traditional structures, the energy exchange efficiency between electron beams and electromagnetic waves shows an exponential downward trend. These two factors jointly restrict the performance of traditional slow-wave structures, making it difficult for their gain levels and saturated output power to break through technical bottlenecks - when operating in the terahertz frequency band, their output power can only be maintained at the milliwatt level, which is far from meeting the demand for high-power devices in actual application scenarios. Summary of the Invention

[0004] The purpose of the present invention is to provide a groove-loaded folded waveguide slow-wave structure with a vertical electron channel to address the problems of insufficient gain and output power in the above-mentioned traditional slow-wave structure.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A groove-loaded folded waveguide slow-wave structure with a vertical electron channel is characterized by including a shell with a slow-wave structure arranged inside the shell. The slow-wave structure is formed by a series of arc-curved waveguides and straight waveguides connected end to end, which is equivalent to a folded waveguide structure formed by a U-shaped bend of a rectangular waveguide. An expansion groove is opened along the midline of the folded waveguide wall, which runs through the entire structure and adapts to the bending deformation. The folded waveguide cavity is connected to the expansion groove through the straight waveguide part to form an electron injection channel.

[0007] Furthermore, the width th of the expanded groove is greater than 0 and less than the width w of the folded waveguide.

[0008] Furthermore, the height hg of the extended groove is one quarter of the period length p minus half of the folded waveguide height h, that is, (p / 4-h / 2).

[0009] Furthermore, the electron channel width s of the internal cavity of the shell is 2 mm, the period length P is 0.6 mm; the folded waveguide width w is 0.77 mm, the folded waveguide height h is 0.125 mm, the expansion groove height hg is 0.0875 mm, and the electron injection channel height wh is 0.2 mm.

[0010] This invention builds on the traditional folded waveguide slow-wave structure by providing an expansion slot conforming to the folded waveguide to connect each waveguide cavity to form an electron channel. Specifically, a continuous expansion slot, adaptively conforming to the folded waveguide, is provided. The straight waveguide portion of the expansion slot connects the folded waveguide cavity to form an electron injection channel. By adopting a conformal design with the expansion slot and the folded waveguide, the electron injection channel can be expanded to its maximum size, thereby carrying a larger electron beam and increasing operating power. Analysis of coupling impedance shows that this folded waveguide slow-wave structure has a higher coupling impedance, which is beneficial for improving gain and output power.

[0011] After adopting the above technical solution, the present invention has the following advantages:

[0012] 1. After the expansion slot is introduced into the present invention, the electron channel is widened, so that a larger electron beam can be used to increase the working power.

[0013] 2. The transmission characteristics of the present invention are superior to those of the traditional structure. Compared with the traditional folded waveguide loaded strip beam electron channel, the reflection coefficient is more than 10dB smaller, which can support the stable operation of the traveling wave tube.

[0014] 3. In terms of coupling impedance, the present invention increases by more than 50% compared with the traditional structure, and is particularly suitable for the design of high-power ribbon beam terahertz devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the traditional folded waveguide structure with vertical electron channels, with gray representing the cross section;

[0016] Figure 2 This is an embodiment of a groove-loaded folded waveguide slow-wave structure with a vertical electron channel, where the gray represents the cross section;

[0017] Figure 3 A front view of a groove-loaded folded waveguide slow-wave structure with a vertical electron channel;

[0018] Figure 4 Schematic diagram comparing the performance of the present invention and the traditional structure; (a) is a traditional folded waveguide slow-wave structure, (b) is a folded waveguide slow-wave structure of an embodiment;

[0019] Figure 5 Schematic diagram of saturation gain and output power of an example of the present invention;

[0020] Figure 6 Schematic diagram of the slow-wave structure of the present invention.

[0021] Figure Number:

[0022] 1 is the shell, 2 is the folded waveguide slow-wave structure; 3 is the expansion slot, and 4 represents the electron injection channel. DETAILED DESCRIPTION

[0023] The technical solution of the present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0024] Figure 1 It is a traditional slow-wave structure. Figure 1 As shown, the traditional slow-wave structure includes a shell 1, in which a folded waveguide slow-wave structure 2 is provided. The electron channel width s in the folded waveguide slow-wave junction 2 is 2 mm, the electron injection channel height wh is 0.2 mm, the folded waveguide width w is 0.74 mm, the folded waveguide height h is 0.125 mm, and the period length P is 0.6 mm.

[0025] Figure 2 The folded waveguide slow-wave structure of this embodiment is shown. Figure 6 FIG. 1 is a schematic diagram of the slow-wave structure of the present invention. Figure 2 As shown, the slow-wave structure includes a housing 1, in which a slow-wave structure 2 is provided. The slow-wave structure is formed by connecting a series of arc-shaped waveguides and straight waveguides end to end, which is equivalent to a folded waveguide structure formed by periodic U-shaped bending of a rectangular waveguide along the electric field. The folded waveguide structure is provided with an expansion slot 3, which is conformal to the folded waveguide structure 2. All the expansion slots of the straight waveguide parts are connected to form electron injection channels 2-4. Figure 3 In this embodiment, the following dimensions are specifically set:

[0026] The width of the electron channel in the cavity inside the shell is s = 2 mm, and the period length is P = 0.6 mm; the width of the middle folded waveguide is w = 0.77 mm, the height of the folded waveguide is h = 0.125 mm, the height of the introduced groove extending in the vertical direction of the folded waveguide is hg = 0.0875 mm, and the height of the electron injection channel is wh = 0.2 mm.

[0027] The operating frequency band of the traditional slow-wave structure and the slow-wave structure of this embodiment is 218-220 GHz, and the cold cavity is analyzed using 3D simulation software. Figure 4 (a) and Figure 4 As shown in (b), compared with the traditional structure, the coupling impedance of the slow-wave structure of this embodiment is increased by 50%, and the power and gain characteristics are greatly improved. Figure 5As shown in the figure, an output power of over 1 kW and a gain of over 40 dB can be achieved in the terahertz band. It can be seen that in the same frequency band, the slow-wave structure of the present invention has a higher gain per unit length and a smaller size, which can save a lot of space.

[0028] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A groove-loaded folded waveguide slow-wave structure with a vertical electron channel, characterized in that: The invention comprises a shell in which a slow-wave structure is arranged. The slow-wave structure is formed by connecting a series of arc-shaped curved waveguides and straight waveguides end to end, which is equivalent to a folded waveguide structure formed by a U-shaped bend of a rectangular waveguide. An expansion groove is provided along the center line of the folded waveguide wall, which runs through the entire wall and adapts to the bending deformation. The expansion groove of the straight waveguide part is connected to the folded waveguide cavity to form an electron injection channel.

2. A groove-loaded folded waveguide slow-wave structure with a vertical electron channel according to claim 1, characterized in that: The width th of the expanded groove is greater than 0 and smaller than the width w of the folded waveguide.

3. The groove-loaded folded waveguide slow-wave structure with a vertical electron channel according to claim 1, characterized in that: The height hg of the extended groove is one quarter of the period length p minus half of the folded waveguide height h, that is, (p / 4-h / 2).

4. A groove-loaded folded waveguide slow-wave structure with a vertical electron channel according to any one of claims 1 to 3, characterized in that: The electron channel width s of the inner cavity of the shell is 2 mm, and the period length P is 0.6 mm; the folded waveguide width w is 0.77 mm, the folded waveguide height h is 0.125 mm, the expansion groove height hg is 0.0875 mm, and the electron injection channel height wh is 0.2 mm.

Images