Elliptical local loading folded waveguide slow wave structure and device

Abstract

The application relates to an ellipsoid local loading folded waveguide slow wave structure and device, the slow wave structure comprising a plurality of folded waveguide units of a periodic structure and an electron beam channel, the folded waveguide unit comprising a straight waveguide section and a connecting waveguide section, and the metal grid forming the folded waveguide unit and the electron beam channel having an ellipsoid local protruding structure towards the straight waveguide section. By loading the ellipsoid local metal structure in the area near the electron beam channel of the straight waveguide section, the reflection of the wide side of the straight waveguide caused by the existence of the electron beam channel can be compensated in the same plane, the matching performance of the slow wave structure is improved, and the application prospect is wide in the field of short millimeter wave and terahertz traveling wave tubes.

Description

Technical Field

[0001] This invention relates to the field of microwave vacuum electronics technology. More specifically, it relates to an ellipsoidal locally loaded folded waveguide slow-wave structure and device. 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 connecting waveguide segments. The electron beam channel is located on the central axis of the folded waveguide slow-wave structure, where '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, larger electron beam channel sizes are often used, exacerbating the deterioration of the folded waveguide's matching and ultimately affecting the device's in-band consistency and other communication characteristics. Summary of the Invention

[0004] In view of this, the present invention proposes an ellipsoidal locally loaded folded waveguide slow wave structure and device.

[0005] In a first aspect, the present invention provides an ellipsoidal locally loaded folded waveguide slow-wave structure, the slow-wave structure comprising multiple folded waveguide units of a periodic structure and an electron beam channel.

[0006] The folded waveguide unit includes a straight waveguide segment and a connecting waveguide segment, and the metal grid forming the folded waveguide unit and the electron beam channel has an ellipsoidal local protrusion structure toward the straight waveguide segment.

[0007] Preferably, the locally protruding structure of the ellipsoid is symmetrical about the axis of the electron injection channel.

[0008] Preferably, the ellipsoidal local protruding structure is symmetric about a symmetry plane of the folded waveguide unit.

[0009] Preferably, the folded waveguide is a rectangular waveguide, and a dimension of the ellipsoidal local protruding structure along the electron beam passage axis is less than half of a length of a narrow side of the straight waveguide section.

[0010] Preferably, the folded waveguide is a rectangular waveguide, and a dimension of the ellipsoidal local protruding structure perpendicular to the electron beam passage axis is greater than a dimension of the electron beam passage and less than a height of the straight waveguide section.

[0011] Preferably, the electron beam passage is a circular cross-section passage.

[0012] Preferably, the ellipsoidal local protruding structure of the metal grid is an ellipsoidal structure about the electron beam axis and a longitudinal symmetry plane of the metal grid.

[0013] A second aspect of the present application provides a traveling wave tube, comprising the ellipsoidal local loading folded waveguide slow wave structure as described above.

[0014] A third aspect of the present application provides a folded waveguide slow wave structure, comprising a folded waveguide and an electron beam passage, the folded waveguide comprising connected straight waveguide sections and connecting waveguide sections, each straight waveguide section having a waveguide space tapering down towards the electron beam passage, and the electron beam passage being a circular cross-section passage.

[0015] According to a fourth aspect of the present application, there is provided a folded waveguide device, comprising the folded waveguide slow wave structure as described above.

[0016] Preferably, the waveguide is a rectangular waveguide, and the waveguide space of each straight waveguide section presents symmetric ellipsoidal tapering on a first side and a second side thereof along a direction of electron beam travel.

[0017] The present application has the following beneficial effects:

[0018] The present application proposes an ellipsoidal local loading folded waveguide slow wave structure, a traveling wave tube and a device, which load an ellipsoidal local metal structure in a region near the electron beam passage of the straight waveguide section, coplanarly compensate and suppress reflection of the straight waveguide wide side due to existence of the electron beam passage, improve matching performance of the slow wave structure, and have wide application prospects in the field of short millimeter wave and terahertz traveling wave tubes.

[0019] The ellipsoidal local loading folded waveguide slow wave structure, the traveling wave tube and the device according to the present application can be widely applied to a new generation of mobile communication equipment, mobile communication base station equipment in broadband wireless mobile communication technology, and transmitting equipment in the field of satellite transmission and the field of broadcast television network. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without any creative effort.

[0021] Figure 1 A schematic diagram of a conventional folded waveguide slow wave structure is shown.

[0022] Figure 2 A schematic diagram of a folded waveguide unit according to an embodiment of the present application is shown.

[0023] Figure 3 A cross-sectional schematic diagram of a folded waveguide unit according to an embodiment of the present application is shown.

[0024] Figure 4 A cross-sectional schematic diagram of a folded waveguide unit according to an embodiment of the present application is shown.

[0025] Figure 5 A comparison diagram between the reflection coefficient of the slow wave structure of the present embodiment and the conventional structure is shown.

[0026] Figure 6 A comparison diagram between the voltage standing wave ratio of the novel structure of the present embodiment and the conventional structure is shown. DETAILED DESCRIPTION

[0027] In order to make the technical solutions and advantages of the present application clearer, the embodiments of the present application will be further described in detail below with reference to the drawings.

[0028] In the terahertz field, in order to realize the high-power continuous wave operation of the device, a larger electron beam channel size is often used, which aggravates the deterioration of the folded waveguide matching, and finally affects the in-band consistency and other communication characteristics of the device. Therefore, the matching of the folded waveguide slow wave structure has become the primary problem to be solved in the application in this field. At present, the matching optimization of the folded waveguide is generally realized by a coupling structure, for example, by setting a gradual change or a sudden change in one or two sizes on the rectangular waveguide. However, for the matching performance of the folded waveguide, the degree of improvement is limited.

[0029] The present application is based on a folded waveguide slow wave structure as shown in Figure 1 The present application proposes a folded waveguide slow wave structure with an ellipsoid locally loaded metal grid. Referring to Figure 2The folded waveguide slow wave structure is symmetrically loaded with ellipsoid partial structures near the electron beam channel region on the wide side of the straight waveguide, with the intersection of the electron beam channel axis and the longitudinal symmetry plane of the metal grating as the center, and the electron beam channel penetrates the slow wave structure along the axis, and other structures coincide with the metal structure of the original folded waveguide.

[0030] The slow wave structure of the embodiment of the present application comprises a plurality of folded waveguide units of periodic structure and an electron beam channel, Figures 2 to 4 One of the folded waveguide units is schematically shown, and the geometric period of the folded waveguide unit is 2p. The metal structure including the metal grating forms a first curved waveguide section 1, a first straight waveguide section 2, a second curved waveguide section 3, a second straight waveguide section 4, and a third curved waveguide section 5, which are sequentially connected, wherein the first curved waveguide section 1 and the third curved waveguide section 5 are symmetric about the midline of the second curved waveguide section 3, the first straight waveguide section 2 and the second straight waveguide section 4 are symmetric about the midline of the second curved waveguide section 2, the first straight waveguide section 2 includes a first metal loading 20 and a second metal loading 22 near the electron beam channel, and the second straight waveguide section 4 includes a third metal loading 40 and a fourth metal loading 42 near the electron beam channel. The electron beam channel at the center position of the first straight waveguide section 2 and the second straight waveguide section 4 penetrates each metal loading 20, 22, 40, and 42.

[0031] In a specific example, the first metal loading, the second metal loading, the third metal loading, and the fourth metal loading are local ellipsoids protruding from the metal grating toward the straight waveguide section, the electron beam channel is a circular cross-section channel, and the center of each metal loading coincides with the axis of the electron beam channel. In a specific example, the waveguide structure of the folded waveguide is a rectangular waveguide, and the waveguide space of each straight waveguide section presents symmetric ellipsoidal reduction on the first side and the second side thereof in the electron beam running direction.

[0032] The length of each metal loading in the straight waveguide section in the direction of the electron beam axis is less than half the size of the straight waveguide section in the direction of the electron beam axis, the height perpendicular to the direction of the electron beam axis is greater than the height of the electron beam channel in the direction of the electron beam axis, and the height is less than the height of the straight waveguide section. When the waveguide is a rectangular waveguide and the electron beam channel is a circular channel, the length of each metal loading in the straight waveguide section in the direction of the electron beam axis is less than half the length of the narrow side of the rectangular waveguide, and the height is greater than the diameter of the electron beam channel and less than the height of the straight waveguide section.

[0033] In a specific example, as shown in Figure 4 the wide side length of the first curved waveguide section 1 is a, the narrow side length of the first curved waveguide section 1 is b, the height of the first straight waveguide section 2 is h, and the radius of the electron beam channel is r c, the first metal loading 20 is a partial ellipsoid structure, the long semi-axis perpendicular to the axis of the electron beam channel is ty, r c ty is less than h / 2, and the short semi-axis is tx, tx is less than b. Thus, the ellipsoid partial protruding structure of the metal grid protruding towards the straight waveguide section forms a waveguide space gradually narrowing towards the electron beam channel near the straight waveguide section. In a preferred embodiment, the metal grid and the metal loading formed in the straight waveguide section on both sides have an ellipsoid shape, and the electron beam channel penetrates through the ellipsoid, as shown in Figure 4

[0034] In the slow wave structure of the present application, by symmetrically loading the ellipsoid partial structure near the region of the electron beam channel on the wide side of the straight waveguide, the reflection of the wide side of the straight waveguide due to the existence of the electron beam channel can be suppressed by coplanar compensation, and the matching performance of the slow wave structure is improved.

[0035] In a specific example, the structural dimensions (unit: mm) of the slow wave structure of the present application are as follows: the length of the wide side of the rectangular waveguide a = 1.9, the length of the narrow side of the rectangular waveguide b = 0.3, the period p = 1.2, the height of the straight waveguide section h = 1, the radius of the electron beam channel r c = 0.22, the half of the dimension of the ellipsoid metal loading perpendicular to the electron beam channel ty = 0.31, and the dimension along the direction of the electron beam channel tx = 0.29. The slow wave structure of the comparative example is the same as the above except for the ellipsoid metal loading. The ellipsoid partial loading folded waveguide slow wave structure of the example and the folded waveguide slow wave structure of the comparative example are simulated by using the three-dimensional electromagnetic software CST Microwave Studio, and the matching performance of the ten-geometric-period slow wave structure is calculated. The matching performance of the two is compared.

[0036] The simulation results of the reflection coefficient (S11) and the voltage standing wave ratio (VSWR) of the folded waveguide slow wave structure of the example of the present application and the folded waveguide slow wave structure of the comparative example are shown in Figure 5 and Figure 6 As can be seen from Figure 5 , the reflection coefficient of the folded waveguide slow wave structure of the present application is smaller, that is, by loading the ellipsoid partial structure in the region of the electron beam channel, the reflection caused by the electron beam channel is reduced by coplanar compensation. Further, as shown in Figure 6 , the voltage standing wave ratio of the slow wave structure of the present application is reduced from 1.28 of the existing structure of the comparative example to 1.02 of the present application at 90-100 GHz. Therefore, the ellipsoid loading folded waveguide slow wave structure proposed in the present application greatly improves the matching performance of the folded waveguide slow wave structure.

[0037] Another embodiment of the present application proposes a folded waveguide slow wave traveling wave tube comprising the above-mentioned folded waveguide slow wave structure. ​

[0038] In the description of the application, relational terms such as first and second and the like can merely be used to distinguish one entity or action from another, without necessarily requiring or implying that the entities or actions are in any way mutually exclusive or directional. Moreover, the terms "comprising," "including," containing" or any other open-ended language, when used in a description of a process, method, article, or apparatus, is intended to encompass the instances of non-exclusive inclusion, such that the process, method, article, or apparatus that comprises a list of elements can include additional elements not expressly listed, or can further include elements that are inherent to such process, method, article, or apparatus. Without limitation, an element preceded by "comprises a" does not, without more constraints, foreclose additional identical elements from being added.

[0039] Obviously, the above-described embodiments of the present application are only examples for clearly illustrating the present application, and are not intended to limit the implementation manners of the present application. Based on the above description, other different forms of changes or variations can be made by those skilled in the art, and it is impossible to enumerate all the implementation manners here. Any obvious changes or variations derived from the technical solutions of the present application are still within the protection scope of the present application.

Claims

1. A locally loaded folded waveguide slow-wave structure on an ellipsoid, characterized in that, It includes multiple folded waveguide units with a periodic structure and electron beam channels. The folded waveguide unit includes a straight waveguide segment and a connecting waveguide segment. The metal grid forming the folded waveguide unit and the electron beam channel has an ellipsoidal local protrusion structure facing the straight waveguide segment. The waveguide space of each straight waveguide segment is symmetrically reduced in an ellipsoidal shape on its first and second sides along the electron beam travel direction. The ellipsoidal local protrusion structure of the metal grid is an ellipsoidal structure about the electron beam channel axis and the longitudinal symmetry plane of the metal grid.

2. The ellipsoidal locally loaded folded waveguide slow-wave structure according to claim 1, characterized in that, The locally protruding structure of the ellipsoid is symmetrical about the axis of the electron injection channel.

3. The ellipsoidal locally loaded folded waveguide slow-wave structure according to claim 1, characterized in that, The locally protruding structure of the ellipsoid is symmetrical about the folded waveguide unit.

4. The ellipsoidal locally loaded folded waveguide slow-wave structure according to claim 1, characterized in that, The folded waveguide is a rectangular waveguide, and the dimension of the locally protruding ellipsoidal structure along the electron beam channel axis is less than half the length of the narrow side of the straight waveguide segment.

5. The ellipsoidal locally loaded folded waveguide slow-wave structure according to claim 1, characterized in that, The folded waveguide is a rectangular waveguide, and the dimension of the locally protruding structure of the ellipsoid perpendicular to the electron beam channel axis is larger than the dimension of the electron beam channel but smaller than the height of the straight waveguide section.

6. The ellipsoidal locally loaded folded waveguide slow-wave structure according to claim 1, characterized in that, The electron injection channel is a circular cross-section channel.

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

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

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