Non-semicircular curved waveguide boundary folded waveguide slow wave structure and traveling wave tube

Abstract

This invention relates to a non-semi-circular curved waveguide boundary folded waveguide slow-wave structure and a traveling wave tube. The folded waveguide slow-wave structure includes a connected straight waveguide section and a curved waveguide section. The inner arc of the curved waveguide section is perpendicularly offset from the extension line of the straight waveguide section boundary towards the slow-wave structure axis, while the outer arc's center is perpendicularly offset from the extension line of the straight waveguide boundary away from the slow-wave structure axis. The width of the straight waveguide section is smaller than the width of the curved waveguide section. By reducing the width of the straight waveguide section, this invention improves the matching performance of the non-semi-circular curved waveguide boundary folded waveguide slow-wave structure. Its voltage standing wave ratio (VSWR) is lower than that of existing curved waveguide folded waveguide slow-wave structures, which is beneficial for improving the load-carrying capacity of short millimeter-wave and terahertz traveling wave tubes using this folded waveguide slow-wave structure.

Description

Technical Field

[0001] This invention relates to the field of microwave vacuum electronics technology. More specifically, it relates to a folded waveguide slow-wave structure with improved connection waveguides and a traveling wave tube. Background Technology

[0002] Traveling wave tubes (TWTs) are microwave vacuum electronic devices characterized by high power, wide bandwidth, and high gain, making them an important millimeter-wave or terahertz power source to meet the application requirements of next-generation high-speed wireless communication systems. Slow-wave structures are a core component of microwave vacuum electronic devices, their function being to reduce the phase velocity of the electromagnetic waves transmitted within them, keeping them synchronized with the electron beam to achieve effective interaction between standing waves. Based on the current development status of short millimeter-wave and terahertz TWTs both domestically and internationally, folded waveguides have become the most commonly used slow-wave structure. For example... Figure 1 As shown, the folded waveguide slow-wave structure is a periodic structure formed by bending a rectangular waveguide along an electric field to form a series of folded waveguide units, including straight waveguide segments and waveguide connection segments. The circular electron beam channel is located on the central axis of the folded waveguide slow-wave structure. Here, 'a' represents the width of the rectangular waveguide, 'b' represents the width of the rectangular waveguide, the geometric period is 2p, the height of the straight waveguide is 'h', and the radius of the electron beam channel is 'r'. c .

[0003] One advantage of folded waveguide slow-wave structures is their simple coupling structure, allowing direct coupling of input or output via rectangular waveguides. Under normal circumstances, their matching characteristics meet engineering application requirements. However, in special applications such as communications, in addition to power, bandwidth, gain, and efficiency requirements, stringent demands are placed on the device's communication characteristics. As a structure formed by bending a rectangular waveguide along the E-plane, the internal reflections of folded waveguides primarily originate from the electron beam channel region. Especially in the terahertz domain, to achieve high-power continuous-wave operation, large electron beam channel sizes are often used, exacerbating the deterioration of folded waveguide matching and ultimately affecting the device's in-band consistency and other communication characteristics. Therefore, matching of folded waveguide slow-wave structures has become a primary problem to be solved for applications in this field.

[0004] To improve the coupling impedance of folded waveguide slow-wave structures, various novel folded waveguide slow-wave structures have been proposed both domestically and internationally. Most of these are achieved by adding slots or ridges to the existing folded waveguide slow-wave structure, which increases the complexity of the manufacturing process. Especially in short millimeter-wave and terahertz frequencies, these methods are difficult to implement in practical applications or achieve their optimal performance due to limited processing space and current manufacturing precision limitations. Summary of the Invention

[0005] In view of this, the present invention proposes a non-semi-circular curved waveguide boundary folded waveguide slow-wave structure, which includes a connected straight waveguide segment, a non-semi-circular curved waveguide segment, and an electron beam channel.

[0006] The width of the straight waveguide segment is less than the width of the curved waveguide segment.

[0007] Preferably, the inner arc point of the curved waveguide segment is perpendicularly offset from the extension line of the straight waveguide segment boundary towards the electron beam channel of the slow wave structure, or the outer arc center of the curved waveguide segment is perpendicularly offset from the extension line of the straight waveguide boundary away from the electron beam channel of the slow wave structure.

[0008] Preferably, the electron injection channel is a circular channel.

[0009] According to another aspect of the present invention, a traveling wave tube is provided, the traveling wave tube comprising the folded waveguide slow wave structure as described above.

[0010] According to another aspect of the present invention, a folded waveguide slow wave structure device is provided, the device comprising the folded waveguide slow wave structure as described above.

[0011] According to another aspect of the present invention, a method for designing a slow-wave structure of a non-semi-circular curved waveguide boundary folded waveguide is provided, the method comprising:

[0012] An initial non-semi-circular curved waveguide boundary folded waveguide slow-wave structure is designed according to requirements. This initial slow-wave structure includes a connected straight waveguide segment, a non-semi-circular curved waveguide segment, and an electron beam channel. The straight waveguide segment and the non-semi-circular curved waveguide segment have the same width side length.

[0013] By using three-dimensional electromagnetic software, the width of the straight waveguide section is reduced, thereby improving port matching within the operating frequency band.

[0014] Preferably, the inner arc point of the curved waveguide segment is perpendicularly offset from the extension line of the straight waveguide segment boundary towards the electron beam channel of the slow wave structure, or the outer arc center of the curved waveguide segment is perpendicularly offset from the extension line of the straight waveguide boundary away from the electron beam channel of the slow wave structure.

[0015] Preferably, in the step of reducing the width of the straight waveguide section, the step size is 0.01 mm.

[0016] Preferably, the performance of the folded waveguide slow wave structure is optimized by changing the distance between the inner arc dot of the curved waveguide section and the vertical deviation of the electron beam channel of the slow wave structure from the extended line of the straight waveguide section boundary.

[0017] Preferably, the performance of the folded waveguide slow wave structure is optimized by changing the distance between the outer arc dot of the curved waveguide section and the vertical deviation of the electron beam channel of the slow wave structure from the extended line of the straight waveguide section boundary.

[0018] The beneficial effects of this invention are as follows:

[0019] Based on conventional folded waveguides, this invention optimizes the matching performance of slow-wave structures without increasing the complexity and precision of the manufacturing process. This is achieved by reducing the width of the straight waveguide section and creating a stepped structure at the junction of the straight and curved waveguides, which compensates for the reflections caused by the curved waveguide structure. This makes it suitable for improving the load-carrying capacity of short millimeter-wave and terahertz traveling wave tubes using this type of slow-wave structure.

[0020] The improved non-semi-circular curved waveguide boundary folded waveguide slow wave structure, traveling wave tube, and device according to the present invention can be widely used in next-generation mobile communication equipment, mobile communication base station equipment in broadband wireless mobile communication technology, and transmission equipment in the fields of satellite launch and broadcast television networks. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A schematic diagram of a folded waveguide unit for a traditional folded waveguide slow wave structure is shown.

[0023] Figure 2A and 2B A schematic diagram of a prior art non-semicircular curved waveguide boundary folded waveguide is shown.

[0024] Figure 3 A schematic diagram of a folded waveguide slow wave structure according to an embodiment of this application is shown.

[0025] Figure 4A and 4B A cross-sectional schematic diagram of a folded waveguide unit according to an embodiment of this application is shown.

[0026] Figure 5 The VSWR comparison curves of the slow-wave structure of Example 1 and the comparative example of the present invention are shown.

[0027] Figure 6 The VSWR comparison curves of the slow-wave structure of Example 2 and the comparative example of the present invention are shown. Detailed Implementation

[0028] To make the present invention, its technical solutions, and advantages clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0029] Figure 1This diagram illustrates a traditional folded waveguide slow-wave structure. The traditional folded waveguide slow-wave structure is a periodic structure formed by bending a rectangular waveguide along an electric field, creating a series of folded waveguide units including straight waveguide segments and connecting waveguide segments. The circular electron beam channel is located on the central axis of the folded waveguide slow-wave structure. The rectangular waveguide has a wide side length 'a' (not shown), a narrow side length 'b', a geometric period of 2p, a straight waveguide height of 'h', and an electron beam channel radius of 'r'. c .exist Figure 1 In the structure shown, the connecting waveguide segment is a semi-circular structure SC, and the inner arc boundary of the connecting waveguide segment near the electron beam channel has a radius r. in The semicircle, the radius r of the outer arc boundary out The inner and outer semicircles of the traveling wave tube (TWT) share the same center O, located at the midpoint of the connecting line between adjacent straight waveguide edges. The matching performance of the TWT can be constantly measured by the voltage-to-wave ratio (VSWR), which determines whether the TWT can operate stably and reliably. A smaller VSWR indicates better matching; a higher VSWR indicates worse matching. Improving TWT matching has two advantages: firstly, it enhances the TWT's load-carrying capacity; secondly, it ensures stable and reliable operation. Slow-wave structure matching is a key factor determining the overall TWT matching. Poor slow-wave structure matching easily causes TWT oscillation. Oscillation can lead to the following problems: reduced efficiency, decreased signal output power, and even disruption of the TWT's normal amplification; if the oscillation frequency falls within the operating frequency band of the device, it will interfere with the device's normal operation, and in electronic countermeasures systems, it may even cause "ringing" and system collapse; if the oscillation frequency falls within the operating frequency band of other equipment on the platform, it will interfere with the corresponding equipment and increase the difficulty of antenna isolation design.

[0030] Figure 2A and 2B This diagram illustrates a prior art non-semi-circular curved waveguide boundary folded waveguide, including a cylindrical electron beam channel 10 and a non-semi-circular curved waveguide cavity structure 20. The slow-wave structure of the non-semi-circular curved waveguide boundary folded waveguide increases coupling impedance by altering the boundary structure of the curved connecting waveguide segment NSC. As shown in the figure, the midpoint of the extended line of the straight waveguide boundary is O. The center of the arc within the connecting waveguide segment is perpendicularly offset from the extended line of the straight waveguide boundary by a distance, with the offset center being O. in The radius is R in The center of the outer circular arc boundary is a distance away from the extension line of the straight waveguide boundary, perpendicular to the electron beam channel. The center of the offset circle is O. out The radius is R out The inner and outer circular arcs and the narrow sides of the straight waveguide section are connected. Although the non-semi-circular curved waveguide boundary folded waveguide slow wave structure can achieve a significant increase in coupling impedance, the changed structure causes additional reflections inside the folded waveguide, resulting in a deterioration in the matching performance of the slow wave structure.

[0031] Therefore, a new structure is needed to match deformable structures such as non-semi-circular curved folded waveguides in order to reduce VSWR.

[0032] Figure 3 A schematic diagram of a folded waveguide slow wave structure according to an embodiment of the present invention is shown. Figure 4A and 4B A cross-sectional schematic diagram of a folded waveguide unit according to an embodiment of this application is shown. As shown, the improved non-semi-circular curved waveguide boundary folded waveguide slow-wave structure proposed in this invention, compared with the existing non-semi-circular curved waveguide boundary folded waveguide structure, compensates for the reflection caused by the non-semi-circular curved waveguide connection structure by reducing the width of the straight waveguide segment, where the reduced straight waveguide segment is denoted as 30, and the stepped structures formed at the junction of the straight waveguide and the curved waveguide are denoted as 301 and 302, thereby optimizing the slow-wave structure matching performance. Specifically, in the improved non-semi-circular curved waveguide boundary folded waveguide slow-wave structure according to an embodiment of this invention, the radius of the circular electron beam channel is r. c The straight waveguide segment has a wide side length of a-2d, a narrow side length of b, a straight waveguide height of h, and the midpoint of the boundary extension line is O; the non-semi-circular curved connecting waveguide segment has a wide side length of a, and the center of the inner arc is perpendicularly offset from the extension line of the straight waveguide boundary by a distance Y. in The center of the offset circle is O. in The distance Y between the center of the outer circular arc boundary and the extension line of the straight waveguide boundary perpendicularly away from the electron beam channel. out The center of the offset circle is O. out The inner and outer circular arcs and the narrow sides of the straight waveguide section are connected.

[0033] As an alternative embodiment of the present invention, an improved slow-wave structure of a non-semi-circular curved waveguide boundary folded waveguide is provided, wherein the radius of the circular electron beam channel is r. c The straight waveguide segment has a wide side length of a-2d, a narrow side length of b, a height of h, and the midpoint of its boundary extension is O. The non-semi-circular curved connecting waveguide segment has a wide side length of a, with the center of the inner arc located at the midpoint O of the straight waveguide boundary extension, and the center of the outer arc offset by a distance Y from the electron beam channel. out The center of the offset circle is O. out Alternatively, the center of the outer arc is located at the midpoint O of the extended line of the straight waveguide boundary, and the center of the inner arc is offset by a distance Y towards the electron beam channel. in The center of the offset circle is O. in .

[0034] This invention further provides a method for improving the matching of slow-wave structures in non-semi-circular curved waveguide boundary folded waveguides, used to optimize the port matching performance of non-semi-circular curved or other deformable folded waveguides. The method includes designing the slow-wave structure of a non-semi-circular curved waveguide boundary folded waveguide as needed, optimizing the width of the straight waveguide segment using three-dimensional electromagnetic software, and improving port matching within the operating frequency band by reducing the width dimension d of the straight waveguide segment, with values ​​ranging from 0 < d < a / 2. In machine tool processing, based on an existing non-semi-circular curved waveguide boundary folded waveguide, reducing the straight waveguide depth a to (ad) can form an improved slow-wave structure. In the step of reducing the width dimension of the straight waveguide segment, the step size is 0.01 mm. As a preferred embodiment, the performance of the folded waveguide slow-wave structure can be optimized by changing the distance between the inner arc dot of the curved waveguide segment and the vertical deviation of the electron beam channel of the slow-wave structure from the extension line of the straight waveguide segment boundary. In a preferred embodiment, the performance of the folded waveguide slow-wave structure can be optimized by changing the distance between the outer arc point of the curved waveguide section and the vertical deviation of the electron beam channel of the slow-wave structure from the extended boundary of the straight waveguide section. The method of optimizing the port matching performance of non-semi-circular curved and other deformable folded waveguides of the present invention, based on conventional folded waveguides without increasing process complexity or precision, compensates for the reflection caused by the special structure of the curved waveguide by reducing the width of the straight waveguide section and the stepped structure formed at the junction of the straight and curved waveguides, thereby optimizing the slow-wave structure matching performance. This method is suitable for improving the load-carrying capacity of short millimeter-wave and terahertz traveling wave tubes using this type of slow-wave structure.

[0035] Example 1

[0036] Using the three-dimensional electromagnetic software CST, the matching performance of the improved non-semi-circular curved waveguide boundary folded waveguide slow wave structure according to the present invention was calculated for ten geometrical periods. The matching performance was then compared with that of a comparable non-semi-circular curved waveguide boundary folded waveguide slow wave structure with the same number of periods and geometric dimensions. The dimensions of the non-semi-circular curved waveguide boundary folded waveguide slow wave structure according to the present invention are shown in the attached figure. Figure 4A and 4B As shown, the rectangular structure 30 of the reduced straight waveguide is divided into two parts, labeled with parameters d and e. The value of d ranges from 0 to 0 < d < a / 2, and the value of e ranges from e to h. The dimensions of the non-semi-circular curved folded waveguide are set as follows (unit: mm): wide side length a = 1.9, narrow side length b = 0.3, period p = 1.22, straight waveguide height h = 0.7, and electron beam channel radius r. c =0.23, the center of the inner arc deviates from Y in the direction of the electron beam channel. in =0.1, the outer arc center is far from the direction of the electron beam channel, deviating from Y. out =0.2, simulation results are as follows Figure 5As shown by the dashed line, the VSWR of the slow-wave circuit in the 88-100GHz band is ≤3.1. Using the method of this invention to improve the matching of the slow-wave structure of a non-semi-circular curved waveguide boundary folded waveguide, the optimal result is obtained by optimizing the parameter d. When d = 0.06mm and e = 0.7mm, the simulation results are as follows. Figure 5 As shown by the solid line, the VSWR of the slow-wave circuit is ≤1.5 in the 88-98GHz band. Simulation results show that the voltage standing wave ratio of the novel structure of this invention is less than the corresponding value of the slow-wave structure of the non-semi-circular curved waveguide boundary folded waveguide, and the port matching is significantly improved.

[0037] Example 2

[0038] Using the three-dimensional electromagnetic software CST, the matching performance of the improved non-semi-circular curved waveguide boundary folded waveguide slow-wave structure according to the present invention was calculated for ten geometrical periods. The matching performance was then compared with that of a comparable non-semi-circular curved waveguide boundary folded waveguide slow-wave structure with the same number of periods and geometric dimensions. The rectangular structure 30 of the reduced straight waveguide was denoted by parameters d and e, where d ranges from 0 to a / 2 and e ranges from e to h. The dimensions of the non-semi-circular curved folded waveguide were set as follows (unit: mm): wide side length a = 1.9, narrow side length b = 0.3, period p = 1.44, straight waveguide height h = 0.8, and electron beam channel radius r. c =0.24, the inner arc is a semicircle, the center of which is located at the midpoint O of the extended line of the straight waveguide boundary, and the center of the outer arc deviates from the Y direction away from the electron beam channel. out =0.2, simulation results are as follows Figure 6 As shown by the thin line, the VSWR of the slow-wave circuit in the 85-100GHz band is ≤5. Using the method of this invention to improve the matching of the slow-wave structure of a non-semi-circular curved waveguide boundary folded waveguide, the optimal result is obtained by optimizing the parameter d. When d = 0.08mm and e = 0.8mm, the VSWR of the slow-wave circuit in the 85-99GHz band is ≤2. Simulation results show that the voltage standing wave ratio of the novel structure of this invention is lower than the corresponding value of the slow-wave structure of a non-semi-circular curved waveguide boundary folded waveguide, and the port matching is significantly improved.

[0039] The folded waveguide slow wave structure of the present invention solves the problem that the matching performance of the folded waveguide slow wave structure at the non-semi-circular curved waveguide boundary is difficult to further optimize. This structure can achieve a smaller VSWR without increasing the complexity and precision of the process, thereby improving the load capacity of the traveling wave tube.

[0040] Another embodiment of this application proposes a folded waveguide slow-wave traveling wave tube, including the folded waveguide slow-wave structure described above.

[0041] Another embodiment of this application proposes a folded waveguide slow-wave device, including the folded waveguide slow-wave structure described above.

[0042] Based on conventional folded waveguides, this invention optimizes the matching performance of slow-wave structures without increasing the complexity and precision of the manufacturing process. This is achieved by reducing the width of the straight waveguide section and creating a stepped structure at the junction of the straight and curved waveguides, which compensates for the reflections caused by the curved waveguide structure. This makes it suitable for improving the load-carrying capacity of short millimeter-wave and terahertz traveling wave tubes using this type of slow-wave structure.

[0043] In the description of this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0044] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A non-semicircular curved waveguide boundary folded waveguide slow wave structure, characterized by, The folded waveguide slow-wave structure includes a connected straight waveguide section, a non-semi-circular curved waveguide section, and an electron beam channel. Wherein, the width of the straight waveguide segment is less than the width of the curved waveguide segment. The wide side boundary of the straight waveguide section is symmetrical with respect to the electron beam channel; The inner arc of the curved waveguide section is perpendicularly offset from the extension line of the straight waveguide section boundary to the electron beam channel of the slow wave structure, or the outer arc of the curved waveguide section is perpendicularly offset from the extension line of the straight waveguide boundary to the electron beam channel of the slow wave structure. The stepped structure formed at the junction of the straight waveguide and the curved waveguide compensates for the reflection of the curved waveguide, thereby reducing the voltage standing wave ratio and improving the matching performance of the slow wave structure.

2. The folded waveguide slow-wave structure according to claim 1, characterized in that, The electron injection channel is a circular channel.

3. A traveling wave tube, characterized in that, The traveling wave tube includes the folded waveguide slow wave structure according to claim 1.

4. A folded waveguide slow-wave structure device, characterized in that, The device includes the folded waveguide slow wave structure according to claim 1.

5. A design method for a slow-wave structure of a non-semi-circular curved waveguide boundary folded waveguide, characterized in that, The method includes An initial non-semi-circular curved waveguide boundary folded waveguide slow wave structure is designed according to requirements. This initial non-semi-circular curved waveguide boundary folded waveguide slow wave structure includes a connected straight waveguide segment, a non-semi-circular curved waveguide segment, and an electron beam channel. The straight waveguide segment and the non-semi-circular curved waveguide segment have the same width length, and the width boundary of the straight waveguide segment is symmetrical with respect to the electron beam channel. By using three-dimensional electromagnetic software, the width dimension d of the straight waveguide section is reduced, thereby improving port matching within the operating frequency band. The inner arc of the curved waveguide section is perpendicularly offset from the extension line of the straight waveguide section boundary to the electron beam channel of the slow wave structure, or the outer arc of the curved waveguide section is perpendicularly offset from the extension line of the straight waveguide boundary to the electron beam channel of the slow wave structure. The stepped structure formed at the junction of the straight waveguide and the curved waveguide compensates for the reflection of the curved waveguide, thereby reducing the voltage standing wave ratio and improving the matching performance of the slow wave structure.

6. The design method for a slow-wave structure of a non-semi-circular curved waveguide boundary folded waveguide according to claim 5, characterized in that, In the step of reducing the width of the straight waveguide section, the step size is 0.01 mm.

7. The design method for a slow-wave structure of a non-semi-circular curved waveguide boundary folded waveguide according to claim 5, characterized in that, The performance of the folded waveguide slow wave structure is optimized by changing the distance between the inner arc dot of the curved waveguide section and the vertical deviation of the electron beam channel of the slow wave structure from the extended line of the straight waveguide section boundary.

8. The design method for a slow-wave structure of a non-semi-circular curved waveguide boundary folded waveguide according to claim 5, characterized in that, The performance of the folded waveguide slow wave structure is optimized by changing the distance between the outer arc point of the curved waveguide section and the vertical deviation of the electron beam channel of the slow wave structure from the extended line of the straight waveguide section boundary.

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