Feedback oscillator structure applied to traveling wave tube

Abstract

The invention discloses a feedback oscillator structure applied to a traveling wave tube. The feedback oscillator structure comprises a waveguide structure, a resonant cavity frequency selection structure and a waveguide power regulation structure which are connected in sequence, the input end of the waveguide structure is connected to the output end of the traveling wave tube, the waveguide structure and the resonant cavity frequency selection structure are connected through a coupling gap, the resonant cavity frequency selection structure and the waveguide power regulation structure are connected through a coupling gap, and the output end of the waveguide power regulation structure is connected to the input end of the traveling wave tube; by utilizing the frequency selection characteristic of the resonant cavity frequency selection structure, the resonant cavity eigenfrequency part in clutters output by the output end of the traveling wave tube is selected, and the clutters are input into the input end of the traveling wave tube again after the power is adjusted, so that the self-oscillation of the traveling wave tube with the adjustable frequency is realized. The feedback oscillator structure does not need a solid-state oscillation source, realizes high-power output of the traveling wave tube when input signals are not added in a terahertz frequency band, has a frequency modulation function, and is relatively pure in frequency spectrum of output signals.

Description

Technical Field

[0001] The invention relates to the technical field of traveling wave tubes, and in particular to a feedback oscillator structure applied to traveling wave tubes. Background Art

[0002] As a microwave power source, the frequency modulation capability of the traditional backward wave tube depends on the adjustment of the emission electron voltage. However, it is a great challenge to ensure the electron flow rate while adjusting the frequency (electron voltage), so the backward wave tube generally has a huge cooling system. The traveling wave tube amplifier is famous for its excellent bandwidth characteristics and amplification ability, and is widely used in aerospace technology, military equipment, medical equipment and other industries. The stability of the electron flow rate of the traveling wave tube is higher than that of the backward wave tube.

[0003] In addition to the backward wave tube, another commonly used solution for high-power and high-frequency power sources is to add one or more amplifiers (usually traveling wave tube amplifiers) after the solid-state oscillator source. This multi-stage amplification system makes the overall structure complex and large in size, and will increase heat dissipation problems.

[0004] In view of this, this application is hereby filed. Summary of the invention

[0005] The purpose of the present invention is to provide a feedback oscillator structure applied to a traveling wave tube. The present invention does not require a solid-state oscillation source. In the terahertz frequency band, the feedback oscillator structure achieves high-power output when the traveling wave tube does not have an input signal, and has a frequency modulation function. The spectrum of the output signal is relatively pure.

[0006] The present invention is achieved through the following technical solutions:

[0007] In a first aspect, the present invention provides a feedback oscillator structure applied to a traveling wave tube, the feedback oscillator structure comprising a waveguide structure, a resonant cavity frequency selection structure and a waveguide power adjustment structure connected in sequence;

[0008] The input end of the waveguide structure is connected to the output end of the traveling wave tube, the waveguide structure is connected to the resonant cavity frequency selection structure through a coupling gap, the resonant cavity frequency selection structure and the waveguide power adjustment structure are connected through a coupling gap, and the output end of the waveguide power adjustment structure is connected to the input end of the traveling wave tube;

[0009] By utilizing the frequency selection characteristics of the resonant cavity frequency selection structure, the eigenfrequency part of the resonant cavity in the clutter output from the output end of the traveling wave tube is selected out, and after the power is adjusted through the waveguide power adjustment structure, it is re-input into the input end of the traveling wave tube to realize the self-excited oscillation of the traveling wave tube with adjustable frequency.

[0010] Further, the waveguide structure is a curved rectangular waveguide, including a standard rectangular waveguide and a curved waveguide;

[0011] A first waveguide port is provided at one end of the standard rectangular waveguide, and the first waveguide port is connected to the output end of the traveling wave tube;

[0012] A second waveguide port is provided at one end of the curved waveguide, and the second waveguide port serves as an output end of the whole, and is used to output the output power from the traveling wave tube;

[0013] A rectangular first coupling slot port is provided on the side wall of the curved waveguide. The first coupling slot port transmits part of the output power from the waveguide to the resonant cavity frequency selection structure by electrical coupling. The coupling slot connects the first coupling slot port and the second coupling slot port.

[0014] Furthermore, the resonant cavity frequency selection structure is a frequency-adjustable resonant cavity structure. After the coupling gap transmits part of the power output from the output end of the traveling wave tube from the waveguide structure to the resonant cavity structure, the electromagnetic wave that meets the eigenfrequency of the resonant cavity structure establishes oscillation in the cavity, while the electromagnetic waves of other frequencies are reflected or rapidly attenuated; the electromagnetic wave of the eigenmode frequency that establishes oscillation in the cavity continues to be transmitted and coupled to the waveguide power adjustment structure.

[0015] Furthermore, the overall shape of the resonant cavity frequency selection structure is a rounded rectangular body, and the working mode of the resonant cavity frequency selection structure is TE101.

[0016] Furthermore, the resonant cavity frequency selection structure includes a resonant cavity of a rounded rectangular shape, a cylindrical first bolt hole is provided at the tail of the resonant cavity, the first bolt hole is used to install a vertically placed tuning bolt, and the eigenfrequency of the resonant cavity frequency selection structure is adjusted by the depth of the tuning bolt extending into (i.e., inserted into) the resonant cavity;

[0017] A second coupling slot port is provided on one side wall of the resonant cavity frequency selection structure, and the second coupling slot port is used to transmit part of the power output from the output end of the traveling wave tube from the first coupling slot port of the waveguide structure to the resonant cavity;

[0018] A third coupling slot port is provided on the other side wall of the resonant cavity frequency selection structure, and the third coupling slot port is used to continue transmitting the electromagnetic wave of the eigenmode frequency of the oscillation established in the cavity and couple it to the waveguide power adjustment structure.

[0019] Further, the waveguide power adjustment structure includes a rectangular waveguide, one end of the rectangular waveguide receives the electromagnetic wave transmitted from the third coupling slot port of the resonant cavity frequency selection structure through the fourth coupling slot port, the third coupling slot port and the fourth coupling slot port are two ports of the same coupling slot, and the other end of the rectangular waveguide is connected to the input end of the traveling wave tube;

[0020] The rectangular waveguide is used to transmit the power transmitted from the resonant cavity frequency selection structure as an input signal to the input port of the traveling wave tube, that is, the third waveguide port.

[0021] Furthermore, the waveguide power adjustment structure also includes a cylindrical second bolt hole, which is used to install a vertically placed adjustment bolt, and the power passing through is adjusted by adjusting the depth of the bolt extending into the rectangular waveguide.

[0022] Furthermore, the ratio of the output power of the second waveguide port from the traveling wave tube to the partial power entering the resonant cavity frequency selection structure is related to the length of the coupling gap between the waveguide structure and the resonant cavity frequency selection structure and the length and width of the port.

[0023] Furthermore, the ratio of the power in the resonant cavity frequency selection structure to the power entering the waveguide power regulation structure is also related to the length of the coupling gap between the resonant cavity frequency selection structure and the waveguide power regulation structure and the length and width of the port.

[0024] Furthermore, the feedback oscillator structure is an all-metal structure.

[0025] Furthermore, the feedback oscillator structure is universal and can be adapted to traveling wave tubes of various frequency bands by adjusting the sizes of the waveguide structure, the resonant cavity frequency selection structure and the waveguide power adjustment structure.

[0026] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0027] 1. The present invention discloses a feedback oscillator structure applied to a traveling wave tube. The present invention does not require a solid-state oscillation source. In the terahertz frequency band, the feedback oscillator structure realizes high-power output of the traveling wave tube when no input signal is added, and has a frequency modulation function. The spectrum of the output signal is relatively pure.

[0028] 2. The feedback oscillator structure of the present invention is applied to a traveling wave tube. The frequency selection characteristic of the resonant cavity is utilized to select the eigenfrequency part of the resonant cavity in the clutter and form a positive feedback loop through the feedback structure to realize the self-excited oscillation of the traveling wave tube with adjustable frequency. The structure is all-metal and the cost is low.

[0029] 3. The feedback oscillator structure of the present invention is applied to a traveling wave tube. The frequency of the output signal can be adjusted by a tuning bolt at the resonant cavity, and the signal power can be adjusted by adjusting the bolts at the output part. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0031] Figure 1 It is a structural schematic diagram of a feedback oscillator structure applied to a traveling wave tube of the present invention;

[0032] Figure 2is a schematic structural diagram of the waveguide structure of the present invention;

[0033] Figure 3 It is a structural schematic diagram of the resonant cavity frequency selection structure of the present invention;

[0034] Figure 4 It is a structural schematic diagram of the waveguide power adjustment structure of the present invention;

[0035] Figure 5 It is a structural schematic diagram of a traveling wave tube of the present invention;

[0036] Figure 6 A simulation model diagram of a traveling wave tube of the present invention;

[0037] Figure 7 When the frequency is 221.94 GHz, (a) the output signal curve and (b) the spectrum of the present invention;

[0038] Figure 8 When the frequency is 228 GHz, (a) the output signal curve and (b) the spectrum of the present invention;

[0039] Fig. 9 Electric field distribution of a circular resonant cavity structure for comparison with the resonant cavity structure of the present invention Figure 1 ;

[0040] Fig.10 Electric field distribution of a circular resonant cavity structure with bolt holes for comparison with the resonant cavity structure of the present invention Figure 2 and the resonant frequencies of different modes solved by the eigenmode solver;

[0041] Fig.11 It is the electric field diagram of the resonant cavity structure of the present invention and the resonant frequencies of different modes solved by the eigenmode solver.

[0042] Reference numerals and corresponding component names:

[0043] 1-waveguide structure; 2-resonant cavity frequency selection structure; 3-waveguide power adjustment structure; 11-first waveguide port; 12-standard rectangular waveguide; 13-bent waveguide; 14-first coupling slot port; 15-second waveguide port; 21-second coupling slot port; 22-resonant cavity; 23-first bolt hole; 24-third coupling slot port; 25-tuning bolt; 31-fourth coupling slot port; 32-second bolt hole; 33-third waveguide port; 34-adjusting bolt. DETAILED DESCRIPTION

[0044] Hereinafter, the term "include" or "may include" used in various embodiments of the present invention indicates the presence of the invented function, operation or element, and does not limit the addition of one or more functions, operations or elements. In addition, as used in various embodiments of the present invention, the terms "include", "have" and their cognates are intended only to indicate specific features, numbers, steps, operations, elements, components or combinations of the foregoing items, and should not be understood as first excluding the presence of one or more other features, numbers, steps, operations, elements, components or combinations of the foregoing items or the possibility of adding one or more features, numbers, steps, operations, elements, components or combinations of the foregoing items.

[0045] In various embodiments of the present invention, the expression "or" or "at least one of A or / and B" includes any combination or all combinations of the words listed at the same time. For example, the expression "A or B" or "at least one of A or / and B" may include A, may include B, or may include both A and B.

[0046] The expressions (such as "first", "second", etc.) used in various embodiments of the present invention may modify the various constituent elements in various embodiments, but may not limit the corresponding constituent elements. For example, the above expressions do not limit the order and / or importance of the elements. The above expressions are only used for the purpose of distinguishing an element from other elements. For example, the first user device and the second user device indicate different user devices, although both are user devices. For example, without departing from the scope of various embodiments of the present invention, the first element may be referred to as the second element, and similarly, the second element may also be referred to as the first element.

[0047] It should be noted that if it is described that one component element is “connected” to another component element, the first component element may be directly connected to the second component element, and a third component element may be “connected” between the first component element and the second component element. Conversely, when one component element is “directly connected” to another component element, it can be understood that there is no third component element between the first component element and the second component element.

[0048] The terms used in various embodiments of the present invention are only used for the purpose of describing specific embodiments and are not intended to limit various embodiments of the present invention. As used herein, the singular form is intended to also include the plural form, unless the context clearly indicates otherwise. Unless otherwise limited, all terms used here (including technical terms and scientific terms) have the same meaning as the meaning generally understood by those of ordinary skill in the art to which the various embodiments of the present invention belong. The terms (such as the terms defined in the dictionary generally used) will be interpreted as having the same meaning as the contextual meaning in the relevant technical field and will not be interpreted as having an idealized meaning or an overly formal meaning, unless clearly defined in various embodiments of the present invention.

[0049] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0050] The main innovation of the feedback oscillator structure of the present invention is the resonant cavity frequency selection structure 2. If a cylindrical resonant cavity is selected, the main resonant mode is the TM010 mode, and the electric field distribution is as follows Fig. 9 Under this condition, if the tuning bolt is inserted from top to bottom, the resonant frequency will not change significantly; however, if the tuning bolt is inserted from the side, the resonant frequency can meet the requirements, and its electric field distribution is as follows Fig.10 shown.

[0051] Depend on Fig.10 It can be seen that the field is squeezed to one side at this time. This resonant cavity can also be used in practical applications. However, in order to further increase the distance between the fundamental mode eigenfrequency of the resonant cavity and other eigenfrequencies, the following is designed: Figure 3 and Fig.11 The resonant cavity shown.

[0052] It is obvious that the distance between the frequencies of the first two modes is further widened (the eigenfrequencies of the first two modes of the circular resonant cavity are 275.9GHz and 371GHz respectively; the eigenfrequencies of the rounded rectangular resonant cavity with bolt holes are 277.9GHz and 410GHz respectively). This can prevent interference from other modes. In addition, the tuning range of the designed rounded rectangular resonant cavity is generally larger than the bandwidth range of the traveling wave tube, so the bandwidth of the oscillator is the bandwidth of the traveling wave tube and will not be reduced.

[0053] In addition, in the waveguide power adjustment structure 3, the present invention adopts the same method of inserting the adjustment bolt into the waveguide horizontally to control the power of the wave passing through instead of using an attenuator, which greatly saves costs. The power entering the waveguide power adjustment structure 3 is generally very small, generally less than 1% of the output power. Even if the reflection caused by inserting the adjustment bolt will cause standing wave oscillation in the place before the adjustment bolt of the waveguide power adjustment structure 3, since the amplitude of the standing wave oscillation is very small, it will not cause instability of the system. In addition, the all-metal structure is conducive to processing and helps heat dissipation.

[0054] Example 1

[0055] like Figure 1 As shown, the present invention is a feedback oscillator structure applied to a traveling wave tube, the feedback oscillator structure includes a waveguide structure 1, a resonant cavity frequency selection structure 2 and a waveguide power adjustment structure 3 connected in sequence; each part transmits microwave energy through a rectangular coupling slot, and the feedback oscillator structure is an all-metal structure.

[0056] The input end of the waveguide structure 1 is connected to the output end of the traveling wave tube, the waveguide structure 1 is connected to the resonant cavity frequency selection structure 2 via a coupling slot (a coupling slot connecting the first coupling slot port 14 and the second coupling slot port 21), the resonant cavity frequency selection structure 2 and the waveguide power adjustment structure 3 are connected via a coupling slot (a coupling slot connecting the third coupling slot port 24 and the fourth coupling slot port 31), and the output end of the waveguide power adjustment structure 3 is connected to the input end of the traveling wave tube;

[0057] By utilizing the frequency selection characteristics of the resonant cavity frequency selection structure 2, the eigenfrequency part of the resonant cavity in the clutter output from the output end of the traveling wave tube is selected out, and after the power is adjusted through the waveguide power adjustment structure 3, it is re-input into the input end of the traveling wave tube, thereby realizing the self-excited oscillation of the traveling wave tube with adjustable frequency.

[0058] In this embodiment, each structure is specifically described as follows:

[0059] First, waveguide structure 1

[0060] like Figure 2 As shown, the waveguide structure 1 is a curved rectangular waveguide, including a standard rectangular waveguide 12 and a curved waveguide 13;

[0061] A first waveguide port 11 is provided at one end of the standard rectangular waveguide 12, and the first waveguide port 11 is connected to the output end of the traveling wave tube;

[0062] A second waveguide port 15 is provided at one end of the curved waveguide 13, and the second waveguide port 15 serves as an output end of the whole, and is used to output the output power from the traveling wave tube;

[0063] A rectangular first coupling slot port 14 is provided on the arc-shaped side wall of the curved waveguide 13 . The first coupling slot port 14 transmits part of the output power from the waveguide to the resonant cavity frequency selection structure 2 by means of electrical coupling.

[0064] Second, the resonant cavity frequency selection structure 2

[0065] like Figure 3 As shown, the resonant cavity frequency selection structure 2 is a frequency-adjustable resonant cavity structure. The overall shape of the resonant cavity frequency selection structure 2 is a rounded rectangular body. The working mode of the resonant cavity frequency selection structure 2 is TE101.

[0066] Specifically, the resonant cavity frequency selection structure 2 includes a rounded rectangular resonant cavity 22, and a cylindrical first bolt hole 23 is provided at the tail of the resonant cavity 22. The first bolt hole 23 is used to install a vertically placed tuning bolt 25. The eigenfrequency of the resonant cavity frequency selection structure 2 is adjusted by the depth of the tuning bolt 25 extending into (i.e., inserted into) the resonant cavity 22.

[0067] A second coupling slot port 21 is provided on one side wall of the resonant cavity frequency selection structure 2, and the second coupling slot port 21 is used to transmit part of the power output from the output end of the traveling wave tube from the first coupling slot port 14 of the waveguide structure 1 to the resonant cavity 22;

[0068] A third coupling slot port 24 is provided on the other side wall of the resonant cavity frequency selection structure 2 . The third coupling slot port 24 is used to continue transmitting the electromagnetic wave of the eigenmode frequency of the oscillation established in the cavity and couple it to the waveguide power adjustment structure 3 .

[0069] It should be noted that the first coupling slot port 14 and the second coupling slot port 21 form an integral rectangular coupling slot.

[0070] In the above technical solution, the second coupling slot port 21 on the left side of the resonant cavity 22 transmits a part of the power output from the output end of the traveling wave tube from the waveguide structure 1 to the resonant cavity 22, and the electromagnetic wave that meets the intrinsic frequency of the resonant cavity structure establishes oscillation in the cavity, while the electromagnetic waves of other frequencies are reflected or rapidly attenuated; then the established resonant cavity oscillation is also coupled to the electromagnetic wave of this frequency to the waveguide power adjustment structure 3 at the third coupling slot port 24 on the right side of the resonant cavity.

[0071] It is worth mentioning that different modes may be excited in the resonant cavity, resulting in a non-unique selected frequency, but fortunately the proportion of signals from other higher-order modes is very small.

[0072] Third, waveguide power adjustment structure 3

[0073] like Figure 4 As shown, the waveguide power adjustment structure 3 is mainly composed of a rectangular waveguide, one end of the rectangular waveguide receives the electromagnetic wave transmitted from the third coupling slot port 24 of the resonant cavity frequency selection structure 2 through the fourth coupling slot port 31, the third coupling slot port 24 and the fourth coupling slot port 31 are two ports of the same coupling slot, and the other end of the rectangular waveguide is connected to the input end of the traveling wave tube;

[0074] The rectangular waveguide is used to transmit the power transmitted from the resonant cavity frequency selection structure 2 as an input signal to the traveling wave tube input port, that is, the third waveguide port 33 .

[0075] It should be noted that the third coupling slot port 24 and the fourth coupling slot port 31 form an integral rectangular coupling slot.

[0076] In addition, the waveguide power adjustment structure 3 also includes a cylindrical second bolt hole 32, the diameter of which is the same as the width of the rectangular waveguide; the second bolt hole 32 is used to install a vertically placed adjustment bolt 34, and the power passing through is adjusted by adjusting the depth of the adjustment bolt 34 extending into the rectangular waveguide.

[0077] The three parts of the above waveguide structure 1, the resonant cavity frequency selection structure 2 and the waveguide power adjustment structure 3 are connected to each other by coupling gaps to realize the function of frequency selection of part of the signal transmitted from the output port of the traveling wave tube and re-inputting it to the input end of the traveling wave tube after adjusting the power.

[0078] In specific implementation, when the traveling wave tube just starts working, since there is no input signal, the output signal spectrum at this time is complex, and signals of various frequencies are mixed. The output signal of the traveling wave tube will be fed into the first waveguide port, thereby entering the feedback oscillator structure, and then most of the power of the signal is output by the second waveguide port 15, and a small part is coupled to the resonant cavity 22 through the first coupling slot port 14 and the second coupling slot port 21. The frequency selection function of the resonant cavity will allow only the signal of the eigenfrequency of the resonant cavity to oscillate in the cavity, and signals of other frequencies will be reflected or quickly attenuated. The electromagnetic wave of the eigenmode frequency that oscillates in the cavity will continue to transmit through the third coupling slot port 24 and the fourth coupling slot port 31 on the right, and enter the input port of the traveling wave tube from the third waveguide port 33. This is a positive feedback until the final steady state is established. In the steady state, the second waveguide port 15 will output a relatively high power and a pure spectrum electromagnetic wave signal, and the frequency is equal to the eigenfrequency of the resonant cavity. The following is the specific process of positive feedback:

[0079] a) There is no input signal to the traveling wave tube, resulting in very low output power and mixed frequencies at the second waveguide port 15 at its output end;

[0080] b) A part of the signal enters the feedback structure and enters the input port of the traveling wave tube after frequency selection and power adjustment;

[0081] c) The single-frequency signal is received at the input end of the traveling wave tube and then amplified;

[0082] d) At this time, the signal spectrum at the output port of the traveling wave tube is relatively pure, and then returns to b).

[0083] There is no negative feedback in this process.

[0084] In addition, the ratio of the output power from the traveling wave tube outputted from the second waveguide port 15 to the partial power entering the resonant cavity frequency selection structure 2 is related to the length of the coupling gap between the waveguide structure 1 and the resonant cavity frequency selection structure 2 and the length and width of the coupling gap port; the ratio of the power in the resonant cavity frequency selection structure 2 to the power entering the waveguide power adjustment structure 3 is also related to the length of the coupling gap between the resonant cavity frequency selection structure 2 and the waveguide power adjustment structure 3 and the length and width of the coupling gap port.

[0085] In order to make the traveling wave tube work in the best amplification state, the transmission curve of the feedback oscillator structure at a certain frequency should be close to the absolute value of the gain of the traveling wave tube in the best working state at this frequency. When the power adjustment bolt is completely released (the electromagnetic wave completely passes through the waveguide power adjustment structure 3), the absolute value of the transmission curve of the feedback oscillator structure should be less than the corresponding traveling wave tube gain (to ensure that enough power can enter the traveling wave tube input port and there will be no undersaturation). The following example illustrates:

[0086] Below is the gain within the bandwidth of a traveling wave tube when it is working normally:

[0087] Frequency (GHz) 212 214 216 218 220 222 224 226 Gain(dB) 32.7 33.58 32.5 33.65 35 35.6 34.4 29.17

[0088] For example, when the frequency is 212 GHz, the traveling wave tube amplifies the power of the input signal by 32.7 dB (1862 times).

[0089] In order to prevent the traveling wave tube from operating in an undersaturated state (input power is less than the optimal input power), the input-output ratio of the feedback structure must be greater than the traveling wave tube gain under this condition. For example, in the above example, when the frequency is 212GHz, the traveling wave tube amplifies the power of the input signal by 32.7dB, so the transmission of the feedback structure must be greater than -32.7dB. Since the amplification gain of the traveling wave tube at different frequencies is different, the transmission of the feedback structure must be greater than the minimum value of the negative traveling wave tube gain (within the operating frequency band). In the above example, the transmission of the feedback structure must be greater than -29.17dB to ensure that the traveling wave tube does not operate in an undersaturated state. In order to prevent the traveling wave tube from operating in an oversaturated state, the adjustment bolts of the waveguide power adjustment structure 3 will again reduce the transmission of the entire feedback structure. During operation, the input power is adjusted by adjusting the bolts of the waveguide power adjustment structure 3 to ensure that the traveling wave tube operates in the optimal state. Since the gain of the traveling wave tube is generally above 20dB, generally speaking, more than 99% of the power will be directly output through the waveguide structure, and only less than 1% of the power will be coupled into the resonant cavity, that is, the power through the feedback structure is much less than the direct output power. In addition, the frequency range of the resonant cavity frequency modulation is generally wider than the bandwidth of the traveling wave tube, so the bandwidth of the traveling wave tube with this feedback structure is theoretically the same as the bandwidth of the traveling wave tube itself.

[0090] It is worth mentioning that the steady-state establishment time of the feedback oscillator structure may be relatively long (tens or even hundreds of nanoseconds), so the structure is not suitable for pulse traveling wave tube amplifiers with a relatively small duty cycle.

[0091] The key points of the present invention are: (1) utilizing the frequency selection characteristics of the resonant cavity, selecting the eigenfrequency part of the resonant cavity in the clutter and forming a positive feedback loop through the feedback structure, so as to realize the self-excited oscillation of the traveling wave tube with adjustable frequency; and the all-metal structure is cheap. (2) the output signal frequency can be adjusted by the tuning bolt at the resonant cavity, and the signal power can be adjusted by adjusting the bolt at the output part.

[0092] Example 2

[0093] like Figure 5 and Figure 6 As shown, the difference between this embodiment and embodiment 1 is that this embodiment is used to prove the effectiveness of the feedback structure. Since the feedback oscillator structure is universal, this embodiment is adapted to a traveling wave tube model working in the terahertz band by adjusting the size of the waveguide structure 1, the resonant cavity frequency selection structure 2 and the waveguide power adjustment structure 3. The two are connected in the simulation software and simulated.

[0094] After connecting the feedback oscillator structure to the traveling wave tube and adjusting the tuning bolts to select two frequency points, the following data is obtained:

[0095] When the frequency is 221.94GHz, the output signal curve is as follows Figure 7 As shown in (a), the spectrum is Figure 7 (b) as shown.

[0096] When the frequency is 228GHz, the output signal curve is as follows Figure 8 As shown in (a), the spectrum is Figure 8 (b) as shown.

[0097] The output power of this feedback oscillator structure is more than 50W at two frequency points, and the spectrum is relatively pure. Although there are some other single-frequency clutter, the proportion is relatively small.

[0098] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A feedback oscillator structure applied to a traveling wave tube, characterized in that: The feedback oscillator structure comprises a waveguide structure (1), a resonant cavity frequency selection structure (2) and a waveguide power adjustment structure (3) which are connected in sequence; The input end of the waveguide structure (1) is connected to the output end of the traveling wave tube, the waveguide structure (1) is connected to the resonant cavity frequency selection structure (2) via a coupling gap, the resonant cavity frequency selection structure (2) and the waveguide power adjustment structure (3) are connected via a coupling gap, and the output end of the waveguide power adjustment structure (3) is connected to the input end of the traveling wave tube; By utilizing the frequency selection characteristics of the resonant cavity frequency selection structure (2), the resonant cavity intrinsic frequency portion of the clutter output from the output end of the traveling wave tube is selected, and after the power is adjusted by the waveguide power adjustment structure (3), it is re-input into the input end of the traveling wave tube, thereby realizing self-excited oscillation of the traveling wave tube with adjustable frequency.

2. The feedback oscillator structure applied to a traveling wave tube according to claim 1, characterized in that: The waveguide structure (1) is a curved rectangular waveguide, comprising a standard rectangular waveguide (12) and a curved waveguide (13); A first waveguide port (11) is provided at one end of the standard rectangular waveguide (12), and the first waveguide port (11) is connected to the output end of the traveling wave tube; A second waveguide port (15) is provided at one end of the curved waveguide (13), and the second waveguide port (15) serves as an output end of the whole and is used to output the output power from the traveling wave tube; A first coupling slot port (14) is provided on the side wall of the curved waveguide (13), and the first coupling slot port (14) transmits part of the output power of the waveguide to the resonant cavity frequency selection structure (2) by means of electrical coupling.

3. The feedback oscillator structure applied to a traveling wave tube according to claim 1, characterized in that: The resonant cavity frequency selection structure (2) is a frequency-adjustable resonant cavity structure. After the coupling gap transmits part of the power output from the output end of the traveling wave tube from the waveguide structure (1) to the resonant cavity structure, an electromagnetic wave that meets the eigenfrequency of the resonant cavity structure oscillates in the cavity, while electromagnetic waves of other frequencies are reflected or attenuated; the electromagnetic wave of the eigenmode frequency that oscillates in the cavity continues to be transmitted and coupled to the waveguide power adjustment structure (3).

4. The feedback oscillator structure applied to a traveling wave tube according to claim 3, characterized in that: The shape of the resonant cavity frequency selection structure (2) is a rounded rectangular body, and the working mode of the resonant cavity frequency selection structure (2) is TE101.

5. The feedback oscillator structure applied to a traveling wave tube according to claim 4, characterized in that: The resonant cavity frequency selection structure (2) comprises a resonant cavity (22) in a rounded rectangular shape, a first cylindrical bolt hole (23) being provided at the tail of the resonant cavity (22), the first bolt hole (23) being used to install a vertically placed tuning bolt (25), and the eigenfrequency of the resonant cavity frequency selection structure (2) being adjusted by the depth of the tuning bolt (25) extending into the resonant cavity (22); A second coupling slot port (21) is provided on one side wall of the resonant cavity frequency selection structure (2), and the second coupling slot port (21) is used to transmit part of the power output from the output end of the traveling wave tube from the waveguide structure (1) to the resonant cavity (22); A third coupling slot port (24) is provided on the other side wall of the resonant cavity frequency selection structure (2), and the third coupling slot port (24) is used to continue transmitting the electromagnetic wave of the eigenmode frequency oscillating in the cavity and couple it to the waveguide power adjustment structure (3).

6. The feedback oscillator structure applied to a traveling wave tube according to claim 1, characterized in that: The waveguide power adjustment structure (3) comprises a rectangular waveguide, one end of the rectangular waveguide receives electromagnetic waves from the resonant cavity frequency selection structure (2) through a fourth coupling slot port (31), the third coupling slot port (24) and the fourth coupling slot port (31) are two ports of the same coupling slot, and the other end of the rectangular waveguide is connected to the input end of the traveling wave tube; The rectangular waveguide is used to transmit the power transmitted from the resonant cavity frequency selection structure (2) as an input signal to the traveling wave tube input port, i.e., the third waveguide port (33).

7. The feedback oscillator structure applied to a traveling wave tube according to claim 6, characterized in that: The waveguide power adjustment structure (3) further comprises a cylindrical second bolt hole (32), wherein the second bolt hole (32) is used to install a vertically placed adjustment bolt (34), and the power passing through is adjusted by the depth of the adjustment bolt (34) extending into the rectangular waveguide.

8. The feedback oscillator structure applied to a traveling wave tube according to claim 2, characterized in that: The ratio of the output power from the traveling wave tube outputted by the second waveguide port (15) to the partial power entering the resonant cavity frequency selection structure (2) is related to the length of the coupling gap between the waveguide structure (1) and the resonant cavity frequency selection structure (2) and the length and width of the coupling gap port.

9. The feedback oscillator structure applied to a traveling wave tube according to claim 1, characterized in that: The feedback oscillator structure is an all-metal structure.

10. The feedback oscillator structure applied to a traveling wave tube according to claim 1, characterized in that: The feedback oscillator structure can be adapted to traveling wave tubes of various frequency bands by adjusting the sizes of the waveguide structure (1), the resonant cavity frequency selection structure (2) and the waveguide power adjustment structure (3).

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