CN115458890A - Ridge loading inclined-entering type multi-path synthesis TE03 mode input coupler - Google Patents

Abstract

The invention discloses a ridge-loaded oblique-entry multiplexed TE03 mode input coupler, which belongs to the technical field of microwave and millimeter wave electric vacuum devices. The input coupler consists of a power splitting section, a ridge-loaded angled entry multiplexing section, and a cut-off circular waveguide section loaded with a lossy ceramic ring. The TE ₀₃ mode with high purity is coupled in the main circular waveguide by adopting the oblique-entry multiplexing structure. By setting the waveguide ridge on the side wall of the main circular waveguide, the position distribution of the rectangular waveguide and the oblique-entry rectangular waveguide and circular waveguide are adjusted. The angle between them is used to suppress the main competition mode of the TE ₀₃ mode in the main circular waveguide, so as to achieve the effects of suppressing miscellaneous modes, reducing reflection coefficient, improving conversion efficiency and expanding input bandwidth. At the same time, the lossy ceramic ring loading can effectively suppress the reverse wave transmission, and its inner radius is larger than the cut-off waveguide of the traditional input coupler, which reduces the probability of electron interception and improves the flow rate of the electron beam.

Description

A ridge-loaded oblique entry multiplexer TE03-mode input coupler

technical field

The invention belongs to the technical field of microwave and millimeter wave electric vacuum devices, and in particular relates to a ridge-loaded oblique entry type multiplexed TE ₀₃ mode input coupler.

Background technique

The cyclotron traveling wave tube is an electric vacuum device based on the relativistic electron cyclotron maser mechanism. It has the characteristics of high power and wide frequency band in the millimeter wave band, so it has broad application prospects in millimeter wave radar, millimeter wave communication, electronic warfare, etc. , Therefore, it has become one of the research hotspots of many scientific research institutes in the world, and the research strength of the domestic cyclotron traveling wave tube is also gradually strengthened.

The input coupler is the key component of the input system of the gyro TWT. Its main function is to couple the input microwave signal into the circular waveguide to excite the working mode TE _mn mode of the gyro TWT. Therefore, the input coupler needs to meet the characteristics of high conversion efficiency, high mode purity, wide operating bandwidth, large power capacity, simple processing, and compact structure during the design process to ensure the good performance of the gyrotron TWT. The input coupler is a three-port device, which are connected to the rectangular input port of the standard rectangular waveguide, the output port of the circular waveguide connected to the electron gun (the waveguide in this direction is a cut-off waveguide, and microwaves cannot be transmitted), and the input port connected to the beam-wave interaction area. connected to the output port of the circular waveguide. There are many types of gyro TWT input couplers. Among them, the circular waveguide side wall excitation structure input coupler is a more commonly used structure in the convoluted traveling wave tube. It is characterized by wide bandwidth and high conversion efficiency. It can increase the bandwidth and suppress the miscellaneous mode by reasonably adding branches. However, for exciting the high-order modes of the circular waveguide, there are a large number of competing modes, and it is difficult to achieve high-purity broadband input.

In the research work of the traditional gyrotron TWT, the low-order mode (such as TE ₀₁ mode, TE ₁₁ mode, TE ₂₁ mode, etc.) is often used as the working mode. However, with the expansion of application fields and the urgent demand for high power , the research on the gyrotron TWT using the higher-order mode as the working mode is gradually carried out. The present invention proposes a convoluted traveling wave tube input coupler that uses circular waveguide TE ₀₃ mode to work. The difficulty lies in that TE ₀₃ mode is a high-order mode, and there are many competing modes that are difficult to suppress, low conversion efficiency, and limited available frequency bandwidth. Design method, it is difficult to obtain TE ₀₃ mode with high purity.

Contents of the invention

The present invention proposes a ridge-loaded oblique-entry multi-channel synthesized TE ₀₃ mode input coupler for a gyrotraveling wave tube, which is used to solve the difficulty of suppressing competing modes when the traditional input coupler of a gyrotron TWT uses high-order modes as the working mode , low conversion efficiency and relatively narrow bandwidth. The coupler is evenly ridged on the circular waveguide in the angle direction, and adopts the oblique-in type multiplexing structure to couple high-purity TE ₀₃ mode in the circular waveguide. The TE ₀₃ mode in the main circular waveguide is suppressed by changing the size, position distribution, and depth of the ridge on the side wall of the main circular waveguide, the position distribution of the obliquely inserted rectangular waveguide, and the angle between the obliquely inserted rectangular waveguide and the circular waveguide. The field distribution of the main competition mode (TE ₀₁ , TE ₀₂ ) improves impedance matching, thereby achieving the effects of suppressing miscellaneous modes, reducing reflection coefficient, improving conversion efficiency, and increasing bandwidth. In addition, a lossy ceramic ring is used to replace the traditional cut-off waveguide to suppress the reverse propagation wave. This structure can make the inner radius of the cut-off wave larger than that of the traditional cut-off waveguide, thus reducing the probability of electronic interception.

The present invention adopts following technical scheme to realize:

A ridge-loaded slant-entry multi-channel synthesis TE ₀₃ mode input coupler for gyrotron traveling wave tubes, applied in the 210-220GHz frequency band, the working mode is TE ₀₃ mode; the structure includes a power distribution part, ridge-loaded slant-entry Multiplexing section and cut-off circular waveguide.

Wherein, the power distribution part divides the standard rectangular waveguide TE ₁₀ -mode microwave signal at the input end into eight equal-amplitude microwave signals evenly distributed along the radial direction.

The ridge-loaded oblique-entry multi-channel synthesis part includes a main circular waveguide, eight oblique-entry rectangular waveguides, and eight waveguide ridges.

The radius of the main circular waveguide is the same as the radius of the beam-wave interaction high frequency system of the cyclotron traveling wave tube.

The angles of the eight oblique-entry rectangular waveguides are evenly distributed outside the main circular waveguide, the angle between the oblique-entry rectangular waveguides and the main circular waveguide is θ ₅ , and θ ₅ ≠90°.

The waveguide ridges are angularly evenly distributed on the inner wall of the main circular waveguide, and have the same spacing as the adjacent coupling holes.

The eight channels of equal-amplitude microwave signals output by the power distribution part are respectively input into one obliquely inserted rectangular waveguide, and then respectively injected into the main circular waveguide through a coupling hole, and finally the TE ₀₃ mode is synthesized in the main circular waveguide.

The cut-off circular waveguide is a circular waveguide loaded with a ceramic ring, and the upper end of the cut-off circular waveguide is connected with the lower port of the main circular waveguide.

Further, the inner radius of the ceramic ring is the same as the radius of the main circular waveguide.

Further, the power distribution part includes a standard rectangular waveguide A, a T-shaped power splitter A, two transitional waveguides A, two T-shaped power splitters B, four transitional waveguides B, and four Y-shaped power splitters , Eight transitional waveguides C. The TE ₁₀ -mode microwave signal is input into the standard rectangular waveguide A, and is divided into two equal-amplitude 1/2 microwave signals by the T-type power divider A; each 1/2 microwave signal passes through a transitional waveguide A and enters the T Type power splitter B, is divided into two equal-amplitude quarter microwave signals; each quarter microwave signal passes through a transitional waveguide B input Y-type power splitter, is divided into two equal-amplitude One-eighth of the microwave signals; eight channels of one-eighth microwave signals respectively pass through a section of transition waveguide C, and finally eight channels of equal-amplitude microwave signals are uniformly output in the radial direction.

Further, the length of the waveguide ridge ranges from 4.4mm to 4.5mm, the width ranges from 0.4mm to 0.5mm, and the depth ranges from 0.4mm to 0.5mm; the distance between the lower end of the waveguide ridge and the main circular waveguide The value range of the lower end distance is 0.05mm-0.15mm.

The invention proposes a ridge-loaded oblique entry multiplexing TE ₀₃ -mode input coupler. The main features are:

(1) Ridges are uniformly added in the angular direction on the side wall of the main circular waveguide. By changing the size, position distribution, and depth of the ridges, the side gallery mode (competition mode) can be effectively suppressed.

(2) The eight-way oblique-incidence rectangular waveguide and the main circular waveguide constitute the oblique-incidence multi-path synthesis part. Eight rectangular waveguides with identical dimensions are evenly distributed on the outside of the main circular waveguide.

(3) Loading a lossy ceramic ring to replace the cut-off waveguide section can increase the radius and effectively suppress the reverse transmission of waves.

Compared with the traditional structure, the innovation of the present invention has two points: 1. By adopting the ridge-loaded multi-channel oblique-inlet rectangular waveguide to synthesize the high-order TE ₀₃ mode in the circular waveguide as the working mode, its advantage lies in that by adjusting the ridge The relevant parameters, the position distribution of the obliquely inserted rectangular waveguide and the angle between it and the main circular waveguide can realize the phase matching and heterogeneous mode suppression of the microwave signal at the coupling hole. 2. The cut-off circular waveguide is replaced by a structure loaded with a lossy ceramic ring, which can effectively suppress the reverse wave, and its inner radius is larger than that of the traditional structure, reducing the probability of electronic interception.

Description of drawings

Figure 1. The overall schematic diagram of the ridge-loaded oblique-entry multiplexer TE ₀₃ -mode input coupler.

Fig. 2 Schematic diagram of partial structure of ridge-loaded oblique-entry multiplexer TE ₀₃ -mode input coupler.

Figure 3. Transmission coefficients of TE ₀₃ mode and main miscellaneous modes TE ₀₁ , TE ₀₂ , and TE ₈₁ of the ridge-loaded oblique entry multiplexer TE ₀₃ mode input coupler.

Figure 4. Reflection coefficient of ridge-loaded oblique entry multiplexer TE ₀₃ -mode input coupler.

Description of reference numerals: 1. Standard rectangular waveguide, 2. Matching groove A, 3. T-type power divider A, 4. Transition waveguide A, 5. Matching groove B, 6. T-type power divider B, 7 . Transition waveguide B, 8. Y-type power divider, 9. Transition waveguide C, 10. Inclined rectangular waveguide, 11. Waveguide ridge, 12. Main circular waveguide, 13. Ceramic ring.

detailed description

Below in conjunction with a design example and accompanying drawing, the present invention is described in further detail:

The technical index requirements of the ridge-loaded oblique-entry multi-channel synthesis TE ₀₃ mode input coupler in the present invention: working mode: TE ₀₃ mode; working frequency: 210-220GHz.

Figure 1 is the overall schematic diagram of the ridge-loaded oblique entry multiplexing TE ₀₃ -mode input coupler; Figure 2 is the partial structure diagram of the ridge-loading oblique entry multiplexing TE ₀₃ -mode input coupler. The structure includes a power distribution part, a ridge-loaded oblique entry multiplexing part and a cut-off circular waveguide.

The power distribution part includes a standard rectangular waveguide A, a T-type power divider A, two transition waveguides A, two T-type power dividers B, four transition waveguides B, four Y-type power dividers, eight Transition waveguide C. The TE ₁₀ -mode microwave signal is input into the standard rectangular waveguide A, and is divided into two equal-amplitude 1/2 microwave signals by the T-type power divider A; each 1/2 microwave signal passes through a transitional waveguide A and enters the T Type power splitter B, is divided into two equal-amplitude quarter microwave signals; each quarter microwave signal passes through a transitional waveguide B input Y-type power splitter, is divided into two equal-amplitude One-eighth of the microwave signal; the eight-way one-eighth microwave signal respectively passes through a section of transition waveguide C, and finally the standard rectangular waveguide TE ₁₀ -mode microwave signal at the input end is divided into eight equal-amplitude microwave signals evenly distributed along the radial direction. Wherein the T-type power divider A is provided with a matching groove A, and the T-type power divider B is provided with a matching groove B.

The ridge-loaded oblique-entry multi-channel synthesis part includes a main circular waveguide, eight oblique-entry rectangular waveguides, and eight waveguide ridges.

The radius of the main circular waveguide is the same as the radius of the beam-wave interaction high frequency system of the cyclotron traveling wave tube.

The angles of the eight oblique-entry rectangular waveguides are evenly distributed outside the main circular waveguide, and the angle between the oblique-entry rectangular waveguides and the main circular waveguide is θ ₅ .

The waveguide ridges are angularly evenly distributed on the inner wall of the main circular waveguide, and have the same spacing as the adjacent coupling holes.

The eight channels of equal-amplitude microwave signals output by the power distribution part are respectively input into one obliquely inserted rectangular waveguide, and then respectively injected into the main circular waveguide through a coupling hole, and finally the TE ₀₃ mode is synthesized in the main circular waveguide.

The cut-off circular waveguide is a circular waveguide loaded with a ceramic ring, and the upper end of the cut-off circular waveguide is connected with the lower port of the main circular waveguide.

The specific parameters of each structure are as follows:

(1) Standard rectangular waveguide A is the standard rectangular waveguide (BJ1800): wide side size: 1.296mm, narrow side size: 0.648mm.

(2) Matching groove A: wide side size: 1.296mm, narrow side size: 0.648mm, depth 1.265mm.

(3) T-type power divider A: Size of two arms: wide side size: 1.296mm, narrow side size: 0.648mm.

(4) Transition waveguide A: realize 90° turning, wide side size 1.296mm, narrow side size: 0.648mm.

(5) Matching groove B: wide side size: 1.296mm, narrow side size: 0.648mm, depth 1.265mm.

(6) T-type power divider B: The size is the same as that of the T-type power divider.

(7) Transition waveguide B: realize 135° turning, wide side size: 1.296mm, narrow side size: 0.648mm.

(8) Transition waveguide C: The size of the input port is the same as that of transition waveguide B; the output port is connected to the Y-shaped power splitter, which is a square with a side length of 1.000 mm.

(9) Y-type power splitter: the size of the input port is the same as the output port of transition waveguide C; the size of the two arms: wide side size: 1.000mm, narrow side size: 0.608mm.

(10) Transition waveguide D: realize the radial inward transmission of eight channels of microwave signals along the main circular waveguide, the wide side size: 1.000mm, and the narrow side size: 0.608mm.

(11) Inclined-in rectangular waveguide: wide side size: 1.000mm, narrow side size: 0.608mm.

(12) Waveguide ridge: wide side size: 4.557mm, narrow side size: 0.470mm, depth: 0.425mm, distance from the lower edge to the lower end of the main circular waveguide: 0.110mm.

(13) Main circular waveguide: radius: 2.350mm, height: 6.000mm.

(14) The lossy ceramic ring material is: BeO-TiO ₂ attenuation ceramics; inner radius: 2.350mm, outer radius: 2.500mm, height: 3.000mm.

Also, θ ₁ =90°, θ ₂ =135°, θ ₃ =60°, θ ₄ =43.6°, and θ ₅ =136.4°.

As shown in Figure 2, the angle θ ₅ between the obliquely inserted rectangular waveguide and the main circular waveguide is determined according to the microwave propagation theory, and the proper inclination angle can be calculated for the TE ₀₁ mode and TE ₀₂ mode. Certain inhibitory effect. Specifically, define a vertex of the coupling hole close to the cut-off circular waveguide as 1 point, a vertex of the coupling hole adjacent to 1 point and far away from the cut-off circular waveguide as 2 points, and a point located on the narrow side of the inclined rectangular waveguide as 3 points, And the three points form a right triangle. According to microwave propagation theory, in order to improve the coupling strength between TE ₁₀ mode and TE ₀₃ mode, and then improve the mode conversion efficiency, it is necessary to ensure that when TE ₀₃ mode propagates from 1 point to 2 points, the phase transformation is the same as that of TE ₁₀ mode from 3 points The phase transformation when propagating to 2 points remains consistent to achieve phase matching. The calculation formula is:

where β ₁₀ is the phase constant of TE ₁₀ mode, β ₀₃ is the phase constant of TE ₀₃ mode, L ₁₂ is the distance between point 1 and point 2, L ₂₃ is the distance between point 2 and point 3, θ ₅ is the angle between the oblique-entry rectangular waveguide and the main circular waveguide.

Fig. 3 shows the transmission coefficients of TE ₀₃ mode and main miscellaneous modes TE ₀₁ and TE ₀₂ of the ridge-loaded oblique entry multiplexing TE ₀₃ mode input coupler of the present invention. It can be seen from the figure that the relative bandwidth of the transmission coefficient S ₂₁ of the TE ₀₃ mode greater than -2.5dB is 2.7%. The transmission parameters from TE ₁₀ mode to other modes (TE _01, TE ₀₂ ) at the input end are relatively low, and they are all below -10dB in the frequency range of 210GHz to 220GHz. ₁₀ - High-efficiency mode conversion of TE ₀₃ , outputting circular waveguide TE ₀₃ mode with higher purity.

Fig. 4 is the reflection coefficient of the ridge-loaded oblique entry multiplexing TE ₀₃ mode input coupler of the present invention. It can be seen from the figure that the reflection coefficient of the input coupler of the gyrotron TWT is less than -5dB in the frequency range from 210GHz to 220GHz.

Claims (4)

1. A ridge-loaded oblique entry multiplexer TE ₀₃ mode input coupler, which is applied in the 210-220GHz frequency band, and the working mode is TE ₀₃ mode; the structure includes a power distribution part, a ridge-loaded oblique entry multiplexer part and cut-off circular waveguide; Wherein, the power distribution part divides the standard rectangular waveguide TE ₁₀ -mode microwave signal at the input end into eight equal-amplitude microwave signals evenly distributed along the radial direction; The ridge-loaded oblique-entry multi-channel synthesis part includes a main circular waveguide, eight oblique-entry rectangular waveguides, and eight waveguide ridges; The radius of the main circular waveguide is the same as the radius of the beam-wave interaction high-frequency system of the cyclotron traveling wave tube; The angles of the eight oblique-entry rectangular waveguides are uniformly distributed on the outside of the main circular waveguide, the angle between the oblique-entry rectangular waveguides and the main circular waveguide is θ ₅ , and θ ₅ ≠90°; The waveguide ridges are evenly distributed angularly on the inner wall of the main circular waveguide, and have the same spacing as the adjacent coupling holes; The eight channels of equal-amplitude microwave signals output by the power distribution part are respectively input into one channel of obliquely inserted rectangular waveguide, and then respectively injected into the main circular waveguide through a coupling hole, and finally the TE ₀₃ mode is synthesized in the main circular waveguide; The cut-off circular waveguide is a circular waveguide loaded with a ceramic ring, and the upper end of the cut-off circular waveguide is connected with the lower port of the main circular waveguide. 2 . The ridge-loaded oblique entry multiplexing TE ₀₃ mode input coupler according to claim 1 , wherein the inner radius of the ceramic ring is the same as the radius of the main circular waveguide. 3 . 3. A kind of ridge-loaded oblique entry type multiplexing TE ₀₃ mode input coupler as claimed in claim 1 or 2, characterized in that, the length range of the waveguide ridge is 4.4mm-4.5mm, and the width is The value range is 0.4mm-0.5mm, the depth value range is 0.4mm-0.5mm; the distance between the lower end of the waveguide ridge and the lower end of the main circular waveguide is 0.05mm-0.15mm. 4. A kind of ridge-loaded oblique entry type input coupler for multiplexing _TE03 mode as claimed in claim 3, characterized in that, the power distribution part comprises a standard rectangular waveguide A, a T-type power divider A, two One transitional waveguide A, two T-shaped power dividers B, four transitional waveguides B, four Y-shaped power dividers, eight transitional waveguides C; TE ₁₀ -mode microwave signal input standard rectangular waveguide A, through T-shaped power divider The device A is divided into two equal-amplitude 1/2 microwave signals; each 1/2 microwave signal passes through a transitional waveguide A and enters the T-shaped power divider B, and is equally divided into two equal-amplitude four-wave signals. 1/8 microwave signal; each 1/4 microwave signal passes through a section of transition waveguide B and enters the Y-type power splitter, and is divided into two 1/8 microwave signals of equal amplitude; 8 1/8 microwave signals are respectively After a section of transitional waveguide C, eight channels of equal-amplitude microwave signals are finally output uniformly in the radial direction.

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