Folded waveguide slow wave circuit

Abstract

A folded waveguide slow wave circuit of the present invention comprises: a first waveguide (10) including a first input unit for inputting electromagnetic waves and a first output unit for outputting the electromagnetic waves, forming a space for transmitting the electromagnetic waves in order to output the electromagnetic waves input from the first input unit, to the first output unit, having a rectangular cross-section, and being repeatedly folded in zigzag while having a constant height; a first beam hole (20) which transmits an electronic beam, passes through the center of the first waveguide (10) from the first input unit to the first output unit, and connects the centers of adjacent zigzag-folded portions of the first waveguide (10) to communicate with each other; a second waveguide (30) including a second input unit to which the electromagnetic waves transmitted from the first output unit of the first waveguide (10) are input and a second output unit through which the electromagnetic waves are output, forming a space for transmitting the electromagnetic waves to output the electromagnetic waves input from the second input unit, through the second output unit, having a rectangular cross-section, and having a shape in which zigzag-folded portions are repeatedly folded while having a higher height toward the second output unit; and a second beam hole (40) which transmits the electron beam, passes through the center of the second waveguide (30) from the second input unit to the second output unit, and connects the centers of the adjacent zigzag-folded portions of the second waveguide (30) to communicate with each other.

Description

Folded waveguide slow-wave circuit

[0001] The present disclosure relates to a folded waveguide slow-wave circuit, and more specifically, to a folded waveguide slow-wave circuit that delays the phase of periodic circuits located at the circuit terminal portion without a delay circuit, thereby exhibiting an effect of increasing output and efficiency by delaying the phase in the slow-wave circuit itself of an FW structure.

[0002] Generally, electromagnetic wave generating devices can be broadly categorized into semiconductor devices and vacuum electronic devices. Among these, vacuum electronic devices are representative high-power electromagnetic wave generating devices that amplify electromagnetic waves by converting the energy of electron beams.

[0003] Among these vacuum electronic devices, the traveling-wave tube (TWT) is a representative type of broadband vacuum electronic device that uses a linear electron beam.

[0004] A traveling wave tube is a vacuum tube for ultra-high frequency amplification through traveling wave amplification. The speed of the electron beam generated inside this tube is designed to be slower than the speed of radio waves, so that when radio waves act on the electron beam, dense areas of electrons are created, and these react in turn to the radio waves, amplifying the energy of the radio waves. Compared to the Krystron, which is used for amplifying and generating high-frequency radio waves of the same level, the range of frequencies it amplifies is wider.

[0005] Because this TWT element has broadband characteristics, it is currently widely used as an electromagnetic wave generator for defense radar, and as the operating frequency increases, it is expected to be utilized in various fields such as high-resolution imaging, communications, medical, and personal search devices. This TWT amplifies electromagnetic waves by converting electron beam energy within a low-speed circuit, and its characteristics are determined by this low-speed circuit.

[0006] Among these, the low-speed circuit with a folded waveguide (FW) structure, suitable for application in the THz band, is a simple waveguide with a bent shape, making it easy to micro-process due to its simple pattern shape. Furthermore, because it possesses broadband, high-output characteristics, it is one of the vacuum electronic components suitable for the defense, medical, and imaging fields.

[0007] The slow-wave circuit of the FW structure has an E-bend structure in the form of a rectangular waveguide. This circuit operates in the lowest mode, TE10 mode, which is the most stable single mode without concern for mode conversion during waveguide transmission. The slow-wave circuit has a structure that delays the phase velocity of the circuit in a bent shape to synchronize the phase velocity with the electron beam. This periodic structure interacts to accelerate and decelerate the electron beam, and in this process, the electromagnetic wave is amplified through energy conversion. However, since the circuit is fixed by the initial conditions of the electron beam, the phase velocity of the electron beam shows a difference at the moment when the electromagnetic wave amplification saturates.

[0008] In the past, performance was improved by using a delay circuit that delays the phase of periodic circuits located at the circuit terminals to increase the saturated output power and increase the driving efficiency.

[0009] However, this method has the problem of not only being complex in structure but also causing output loss because it requires a separate delay circuit with phase delay at the circuit end.

[0010] Therefore, there is a need for the development of a folded waveguide low-wave circuit that delays the phase in the low-wave circuit of the FW structure itself without having a delay circuit that delays the phase of periodic circuits located at the circuit termination portion, thereby achieving the effect of increasing output and efficiency.

[0011] The present invention has been devised to solve the above problems, and the purpose of the present invention is to provide a folded waveguide low-speed circuit that delays the phase in the low-speed circuit of the FW structure itself without having a delay circuit that delays the phase of periodic circuits located at the circuit termination portion, thereby achieving an effect of increasing output and efficiency.

[0012] According to one embodiment of the present disclosure, a folded waveguide low-speed circuit comprises: a first waveguide (10) having a first input portion for inputting an electromagnetic wave and a first output portion for outputting an electromagnetic wave, the first waveguide having a rectangular cross-section, the same height, and a shape that is folded in a zigzag pattern repeatedly to form a space for transmitting an electromagnetic wave so that the electromagnetic wave input from the first input portion is output to the first output portion; a first beam hole (20) that transmits an electron beam and penetrates the center of the first waveguide (10) from the first input portion to the first output portion and connects the centers of adjacent zigzag-folded portions of the first waveguide (10) to each other so that they are in communication with each other; A second input section into which electromagnetic waves transmitted from a first output section of the first waveguide (10) are input and a second output section into which electromagnetic waves are output are provided, and a space for transmitting electromagnetic waves so that the electromagnetic waves input from the second input section are output to the second output section is formed, the second waveguide (30) having a rectangular cross-section, and having a height that gradually increases toward the second output section and is folded in a zigzag pattern repeatedly; and a second beam hole (40) that transmits an electron beam and penetrates the center of the second waveguide (30) from the second input section to the second output section and connects the centers of adjacent zigzag-folded portions of the second waveguide (30) so as to be in communication with each other.

[0013] In addition, the height that becomes increasingly higher as it goes toward the second output section of the second waveguide (30) may have a height according to the following formula.

[0014] h n = a*h n+1

[0015] (n is the order of the height increased by the zigzag-folded portion of the second waveguide (30) from the same height of the first waveguide (10), and a is the height increase of the zigzag-folded portion of the second waveguide (30) and is a constant within the range of 1.05 to 1.15.)

[0016] Additionally, the first beam hole (20) and the second beam hole (40) can be connected to each other in a straight line.

[0017] In addition, the section having an increasingly higher height as it goes from the second waveguide (30) to the second output section may be the entire second waveguide (30) or a part of the second waveguide (30) close to the second output section.

[0018] The folded waveguide slow-wave circuit according to various embodiments of the present disclosure, unlike the conventional waveguide slow-wave circuit, does not have a delay circuit that delays the phase of periodic circuits located at the circuit terminal portion, but delays the phase in the slow-wave circuit of the FW structure itself, so that not only is the structure simple, but output loss is reduced, and the effect of increasing output and efficiency can be exhibited.

[0019] Furthermore, various embodiments of the present disclosure have the effect of increasing output performance compared to a typical FW circuit of the same length. Accordingly, the device can be further miniaturized for better output performance, and this can play a significant role in the development of a TWT that achieves high output characteristics.

[0020] FIG. 1 is a drawing showing the overall structure and a partially enlarged internal structure of a folded waveguide (FW) low-speed circuit according to the present invention.

[0021] FIG. 2 is a drawing showing a folded waveguide (FW) low-speed circuit to which an MPT structure according to the present invention is applied.

[0022] FIG. 3 is a drawing showing the change in slope of the straight section 'h' of a folded waveguide (FW) low-speed wave circuit to which an MPT structure according to the present invention is applied.

[0023] FIG. 4 is a diagram showing the change in beam energy of a folded waveguide (FW) low-speed wave circuit to which an MPT structure according to the present invention is applied.

[0024] FIG. 5 is a graph showing the output characteristics of a folded waveguide (FW) low-speed circuit to which an MPT structure according to the present invention is applied.

[0025] Hereinafter, some embodiments of the present disclosure will be described in detail with reference to exemplary drawings. When adding reference numerals to components in each drawing, identical components may have the same numerals as much as possible even if they are shown in different drawings. In addition, when describing the present embodiments, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the technical idea of ​​the present invention, the detailed description may be omitted. When "includes," "has," "consists of," etc. are used in this specification, other parts may be added unless "only" is used. When a component is expressed in the singular, it may include a case in which the plural is included unless specifically stated otherwise.

[0026] Additionally, terms such as first, second, A, B, (a), (b), etc. may be used to describe components of the present disclosure. These terms are only intended to distinguish the components from other components, and the nature, order, sequence, or number of the components are not limited by the terms.

[0027] In a description of the positional relationship of components, when it is described that two or more components are "connected," "combined," or "connected," it should be understood that the two or more components may be directly "connected," "combined," or "connected," but that the two or more components may also be further "interposed" with another component to be "connected," "combined," or "connected." Here, the other component may be included in one or more of the two or more components that are "connected," "combined," or "connected" to each other.

[0028] In the description of the temporal flow relationship related to components, operation methods, or manufacturing methods, for example, when the temporal or flow relationship is described as “after”, “following”, “next to”, “before”, etc., it may also include cases where it is not continuous, unless “immediately” or “directly” is used.

[0029] Meanwhile, when numerical values ​​or corresponding information (e.g., levels, etc.) for components are mentioned, even without separate explicit description, the numerical values ​​or corresponding information may be interpreted as including an error range that may occur due to various factors (e.g., process factors, internal or external impact, noise, etc.).

[0030] Hereinafter, a folded waveguide low-speed circuit according to embodiments of the present disclosure will be described in detail with reference to the relevant drawings.

[0031] FIG. 1 is a drawing showing the overall structure and a partially enlarged internal structure of a folded waveguide (FW) low-speed circuit according to the present invention, and FIG. 2 is a drawing showing a folded waveguide (FW) low-speed circuit to which an MPT structure according to the present invention is applied.

[0032] As shown in FIG. 1, the folded waveguide low-speed circuit according to the present invention includes a first waveguide (10); a first beam hole (20); a second waveguide (30); and a second beam hole (40).

[0033] The first waveguide (10) is provided with a first input section (11) into which electromagnetic waves are input and a first output section (12) from which electromagnetic waves are output, and forms a space for transmitting electromagnetic waves so that the electromagnetic waves input from the first input section are output to the first output section. In addition, the first waveguide (10) has a rectangular cross-section, has the same height, and is formed in a shape that is folded in a zigzag pattern (i.e., a periodically folded shape). The upper and lower portions of the zigzag pattern-folded portion of the first waveguide (10) are formed in a U shape.

[0034] The reason the waveguide has a folded shape like this is to effectively reduce the speed of electromagnetic waves. Typically, in electromagnetic wave interaction circuits, the speed of electromagnetic waves traveling through the waveguide is much faster than the speed of the electron beam. Therefore, forming the waveguide in a folded shape can effectively reduce the speed of electromagnetic waves interacting with the electron beam. Furthermore, waveguides with this folded shape are widely used for electromagnetic wave generation or amplification due to their simple structure and relatively wide operating frequency band.

[0035] In addition, the folded waveguide structure has the advantages of high power capacity while having excellent broadband performance, high mechanical strength, good heat dissipation, large power capacity, relatively easy processing, and a relatively simple input / output coupling structure.

[0036] It is preferable that the above first waveguide (10) has a uniform rectangular cross-sectional shape.

[0037] As illustrated in Fig. 1, a is the width of the rectangular waveguide, b is the thickness of the rectangular waveguide, r is the radius of the beam hole, h is the height of the rectangular waveguide, and p is the axial length of one zigzag periodic structure.

[0038] An electromagnetic wave absorber is inserted into the terminal of the first output section (12), and the electromagnetic wave absorber is known to have a role of catching oscillations generated by reflected waves generated at each stage, that is, removing oscillations generated by going back and forth as reflected waves at the terminal of each stage.

[0039] The above first beam hole (20) transmits an electron beam, and is formed by protruding so as to penetrate the center of the first waveguide (10) from the first input section to the first output section and to connect the centers of adjacent zigzag-folded portions of the first waveguide (10) to each other. The beam hole may be circular or polygonal in shape.

[0040] The size of the above beam hole can be varied depending on the characteristics of the electron beam.

[0041] The second waveguide (30) is provided with a second input portion (31) into which electromagnetic waves transmitted from the first output portion of the first waveguide (10) are input, and a second output portion (32) into which electromagnetic waves are output, and forms a space for transmitting electromagnetic waves so that the electromagnetic waves input from the second input portion are output to the second output portion. It has a rectangular cross-section, and has a height that gradually increases as it goes toward the second output portion, and has a shape that is folded in a zigzag pattern. The upper and lower portions of the zigzag pattern-folded portion of the second waveguide (30) are U-shaped, similar to the first waveguide (10).

[0042] The above second waveguide (30), like the above first waveguide (10), may have a uniform rectangular cross-sectional shape.

[0043] An electromagnetic wave absorber is inserted at the end of the second input section (31) as in the first output section (12), and the electromagnetic wave absorber is known to have a role of catching oscillations generated by reflected waves generated at each stage, that is, removing oscillations generated by going back and forth as reflected waves at the end of each stage.

[0044] In some embodiments, the entire cross-sectional area of ​​the second waveguide (30) may be made the same as that of the first waveguide (10). That is, in order to make the cross-sectional area of ​​the second waveguide (30) the same as that of the first waveguide (10), the cross-sectional area of ​​a portion having an increasingly higher height may be made to become increasingly smaller as it goes toward the second output section of the second waveguide (30).

[0045] The second beam hole (40) transmits an electron beam and is formed by protruding so as to penetrate the center of the second waveguide (30) from the second input section to the second output section and to connect the centers of adjacent zigzag-folded portions of the second waveguide (30) to each other.

[0046] The first waveguide (10) and the first beam hole (20), and the second waveguide (30) and the second beam hole (40) can be formed within a block of a predetermined material. That is, the waveguide and the beam hole can be configured to be formed within a block of a predetermined material.

[0047] At this time, the block may be made of a metal material such as oxygen-free high conductivity copper (OFHC). The inner surface of the waveguide and beam hole may also be coated with a metal layer.

[0048] The folded waveguide low-speed circuit of the present invention, having the above configuration, can overcome the limits of output and efficiency by further configuring the height of the waveguide in a zigzag-like repeated folded shape to become increasingly higher so as to have electromagnetic wave delay characteristics in the terminal region of the FW low-speed circuit for TWT having a periodic structure.

[0049] As illustrated in Fig. 2, the circuit is configured with periodic electromagnetic wave straight sections, such as h0 and h1, and then, by applying multiple stages of physical path delay, such as h2 to h4, to the terminal close to the second output section, the phase velocity is delayed. This effect helps synchronize the variable electron beam phase velocity, thereby increasing the energy conversion efficiency of the circuit and resulting in an increase in output.

[0050] FIG. 3 is a drawing showing the change in slope of the straight section 'h' of a folded waveguide (FW) low-speed wave circuit to which an MPT structure according to the present invention is applied.

[0051] As a result of verifying the performance of the folded waveguide slow-wave circuit of the present invention through simulation, it was found that, in order to fundamentally secure stability, the circuit at the terminal part, i.e., the part where the output power saturates, was implemented with a multi-step phase-velocity taper (MPT) that delays the physical length of the straight section 'h' as ​​shown in Fig. 3, thereby improving efficiency and increasing output. Of course, it was possible to overcome saturation and increase output while maintaining the circuit length.

[0052] FIG. 4 is a drawing showing a change in beam energy of a folded waveguide (FW) low-speed circuit to which an MPT structure according to the present invention is applied, and FIG. 5 is a graph showing the output characteristics of a folded waveguide (FW) low-speed circuit to which an MPT structure according to the present invention is applied.

[0053] As shown in Fig. 4, since the speed change is large in the latter half of the circuit, a large deceleration occurs, as shown in the beam energy change graph, and eventually the delay of the circuit is similarly delayed.

[0054] Circuits using MPT demonstrate improved performance compared to conventional FW circuits of the same length. Comparing the performance of the MPT circuit configured as shown in Fig. 3 with that of a conventional circuit, output performance increased by approximately 38% at 122 GHz, as shown in Fig. 5. This will significantly contribute to the development of smaller, higher-output TWTs.

[0055] In addition, it is preferable that the height, which gradually increases as it goes toward the second output section of the second waveguide (30), has a height according to the following formula.

[0056] h n = a*h n+1

[0057] (Here, n is the order of the height increased by the zigzag-folded portion of the second waveguide (30) from the same height of the first waveguide (10), and a is the height increase of the zigzag-folded portion of the second waveguide (30) and is a constant within the range of 1.05 to 1.15.)

[0058] In addition, it is preferable that the first beam hole (20) and the second beam hole (40) are connected to each other in a straight line.

[0059] In addition, in the present invention, a section having an increasingly higher height as it goes from the second waveguide (30) to the second output section can be the entire second waveguide (30), and can be a part of the second waveguide (30) close to the second output section.

[0060] The above description is merely an illustrative example of the technical idea of ​​the present disclosure, and those skilled in the art to which the present disclosure pertains will appreciate that various modifications and variations can be made without departing from the essential characteristics of the technical idea of ​​the present disclosure. In addition, the present embodiments are not intended to limit the technical idea of ​​the present disclosure but rather to explain it, and therefore the scope of the technical idea of ​​the present disclosure is not limited by these embodiments. The scope of protection of the present disclosure should be interpreted by the claims below, and all technical ideas within a scope equivalent thereto should be interpreted as being included within the scope of the rights of the present disclosure.

[0061]

[0062] CROSS-REFERENCE TO RELATED APPLICATION

[0063] This patent application claims priority under 35 USC §119(a) to Korean Patent Application No. 10-2023-0152534, filed in Korea on November 7, 2023, the entire contents of which are incorporated herein by reference. Furthermore, this patent application claims priority in countries other than the United States for the same reasons, the entire contents of which are incorporated herein by reference.

Claims

1. A first waveguide having a first input section into which electromagnetic waves are input and a first output section from which electromagnetic waves are output, and forming a space for transmitting electromagnetic waves so that electromagnetic waves input from the first input section are output to the first output section, the first waveguide having a rectangular cross-section, the same height, and a shape that is folded in a zigzag pattern; A first beam hole that transmits an electron beam and penetrates the center of the first waveguide from the first input portion to the first output portion and connects the centers of adjacent zigzag-folded portions of the first waveguide so as to be in communication with each other; A second waveguide having a second input section into which an electromagnetic wave transmitted from a first output section of the first waveguide is input and a second output section from which an electromagnetic wave is output, and forming a space for transmitting an electromagnetic wave so that the electromagnetic wave input from the second input section is output to the second output section, the second waveguide having a rectangular cross-section, and having a shape in which the height increases as it goes toward the second output section and is folded in a zigzag pattern; A folded waveguide low-wave circuit characterized by comprising a second beam hole that transmits an electron beam and penetrates the center of the second waveguide from the second input portion to the second output portion and connects the centers of adjacent zigzag-folded portions of the second waveguide so as to be in communication with each other.

2. In paragraph 1, A folded waveguide low-speed circuit characterized in that the height of the second output section of the second waveguide becomes increasingly higher as it goes toward the second output section, and has a height according to the following formula. h n = a*h n+1 Here, n is the order of the height of the zigzag-folded portion of the second waveguide increased from the same height of the first waveguide, and a is the height increase of the zigzag-folded portion of the second waveguide, which is a constant within the range of 1.05 to 1.

15.

3. In paragraph 1, A folded waveguide low-speed circuit characterized in that the first beam hole and the second beam hole are connected to each other in a straight line.

4. In paragraph 1, A folded waveguide low-speed circuit, characterized in that the section in which the height increases as it goes from the second waveguide to the second output section is the entirety of the second waveguide or a part of the second waveguide close to the second output section.

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