A feedback oscillator structure applied to a traveling wave tube

Abstract

The application discloses a feedback oscillator structure applied to a traveling wave tube, which comprises waveguide structures, 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 with 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 with the input end of the traveling wave tube; the frequency selection characteristic of the resonant cavity frequency selection structure is used to select the resonant cavity eigenfrequency part from the noise wave output from the output end of the traveling wave tube, the power is adjusted, and then the selected part is input to the input end of the traveling wave tube, so that the self-excited oscillation of the traveling wave tube with adjustable frequency is realized. The application does not need a solid-state oscillation source, in the terahertz frequency band, the feedback oscillator structure can realize the high-power output of the traveling wave tube without input signals, has the frequency modulation function, and the frequency spectrum of the output signal is relatively pure.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of traveling wave tube technology, and particularly relates to a feedback oscillator structure applied to a traveling wave tube. BACKGROUND

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

[0003] In addition to backward wave tube, another common solution for high-power high-frequency power source is to add one or more stages of amplifier (generally traveling wave tube amplifier) after solid-state oscillation source. This multi-stage amplification system makes the overall structure complex, large in size, and increases the heat dissipation problem.

[0004] Therefore, the present application is proposed. SUMMARY

[0005] The present application aims to provide a feedback oscillator structure applied to a traveling wave tube. The feedback oscillator structure does not need a solid-state oscillation source, and realizes high-power output of the traveling wave tube without input signal in the terahertz frequency band, has frequency modulation function, and the frequency spectrum of the output signal is relatively pure.

[0006] The present application is realized by the following technical scheme:

[0007] In a first aspect, the present application provides a feedback oscillator structure applied to a traveling wave tube, which comprises waveguide structure, resonant cavity frequency selection structure and waveguide power regulation 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 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.

[0009] The resonant cavity eigenfrequency part in the spurious wave output from the output end of the traveling wave tube is selected by the frequency selection characteristic of the resonant cavity frequency selection structure, and then re-inputs the input end of the traveling wave tube after adjusting the power by the waveguide power regulation structure, so as to realize self-excited oscillation of the traveling wave tube with adjustable frequency.

[0010] Further, the waveguide structure is a curved rectangular waveguide, which includes a standard rectangular waveguide and a curved waveguide.

[0011] One end of the standard rectangular waveguide is provided with a first waveguide port, and the first waveguide port is connected to the output end of the traveling wave tube;

[0012] One end of the curved waveguide is provided with a second waveguide port, and the second waveguide port is used as the overall output end for outputting the output power from the traveling wave tube;

[0013] A rectangular first coupling slot port is arranged on the side wall of the curved waveguide, and the first coupling slot port is used to transmit part of the output power from the traveling wave tube to the resonant cavity frequency selection structure in an electrically coupled manner.

[0014] Further, the resonant cavity frequency selection structure is a resonant cavity structure with adjustable frequency, and after the part of the output power from the output end of the traveling wave tube is transmitted from the waveguide structure to the resonant cavity structure through the coupling slot, the electromagnetic wave with the intrinsic frequency of the resonant cavity structure is established in the cavity to oscillate, and the electromagnetic wave with other frequencies is reflected or rapidly attenuated. The electromagnetic wave with the intrinsic mode frequency established in the cavity continues to be transmitted and coupled to the waveguide power regulation structure.

[0015] Further, the resonant cavity frequency selection structure is a round rectangular body as a whole, and the working mode of the resonant cavity frequency selection structure is TE101.

[0016] Further, the resonant cavity frequency selection structure includes a round rectangular resonant cavity, and a first bolt hole in a cylindrical shape is arranged at the tail of the resonant cavity, the first bolt hole is used to install a vertically placed tuning bolt, and the intrinsic frequency of the resonant cavity frequency selection structure is adjusted by adjusting the depth of the tuning bolt extending into (i.e. inserted into) the resonant cavity.

[0017] A second coupling slot port is arranged on one side wall of the resonant cavity frequency selection structure, and the second coupling slot port is used to transmit part of the output power 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 arranged on the other side wall of the resonant cavity frequency selection structure, and the third coupling slot port is used to continue to transmit and couple the electromagnetic wave with the intrinsic mode frequency established in the cavity to the waveguide power regulation structure.

[0019] Further, the waveguide power regulation 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 third waveguide port, i.e. the input end port of the traveling wave tube.

[0021] Further, the waveguide power adjustment structure further comprises a cylindrical second bolt hole for mounting an adjustment bolt vertically placed, and the power passing through is adjusted by adjusting the depth of the adjustment bolt into the rectangular waveguide.

[0022] Further, the ratio of the output power 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] Further, the ratio of the power in the resonant cavity frequency selection structure to the power entering the waveguide power adjustment structure is also related to the length of the coupling gap between the resonant cavity frequency selection structure and the waveguide power adjustment structure and the length and width of the port.

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

[0025] Further, the feedback oscillator structure has universality and can be applied 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 application has the following advantages and beneficial effects:

[0027] 1. The feedback oscillator structure applied to the traveling wave tube does not need a solid-state oscillation source, realizes high-power output of the traveling wave tube without input signal in the terahertz frequency band, has a frequency modulation function, and the frequency spectrum of the output signal is relatively pure.

[0028] 2. The feedback oscillator structure applied to the traveling wave tube utilizes the frequency selection characteristic of the resonant cavity to select the resonant cavity eigenfrequency part in the spurious wave to form a positive feedback loop through the feedback structure, realizes self-excitation oscillation of the adjustable frequency traveling wave tube, and is an all-metal structure with low cost.

[0029] 3. The feedback oscillator structure applied to the traveling wave tube can adjust the output signal frequency through the tuning bolt at the resonant cavity and adjust the signal power through the bolt of the output part. DETAILED DESCRIPTION

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

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

[0032] Figure 2Structure diagram of the waveguide structure of the present application;

[0033] Figure 3 Structure diagram of the resonant cavity frequency selection structure of the present application;

[0034] Figure 4 Structure diagram of the waveguide power adjustment structure of the present application;

[0035] Figure 5 Structure diagram of the traveling wave tube of the present application;

[0036] Figure 6 Simulation model diagram of the traveling wave tube of the present application;

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

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

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

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

[0041] Figure 11 Electric field diagram of the resonant cavity structure of the present application and resonant frequencies of different modes solved by the eigenmode solver.

[0042] Reference signs 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 gap port; 15-second waveguide port; 21-second coupling gap port; 22-resonant cavity; 23-first bolt hole; 24-third coupling gap port; 25-tuning bolt; 31-fourth coupling gap port; 32-second bolt hole; 33-third waveguide port; 34-adjustment bolt. DETAILED DESCRIPTION

[0044] Hereinafter, the term "include" or "may include" used in various embodiments of the present application indicates existence of the inventive function, operation, or element, and does not limit one or more additional functions, operations, or elements. Also, the terms "include", "have", and their conjugates as used in various embodiments of the present application, are merely intended to denote specific features, numbers, steps, operations, elements, components, or combinations thereof, and are not intended to, in and of themselves, exclude the existence of one or more other features, numbers, steps, operations, elements, components, or combinations thereof, unless clearly indicated so in the context.

[0045] In various embodiments of the present application, the expression "or" or "at least one of A or / and B" includes any and all combinations of the listed terms. For example, the expression "A or B" or "at least one of A or / and B" can include A, can include B, or can include both A and B.

[0046] The expressions, such as "first", "second", and the like, used in various embodiments of the present application can modify various components in various embodiments, but can not limit the corresponding components. For example, the above expressions do not limit the order and / or importance of the elements. The above expressions are used merely for the purpose of distinguishing a component from other components. For example, a first user device and a second user device indicate different user devices, although both are user devices. For example, a first element can be termed a second element, and likewise, a second element can be termed a first element, without departing from the scope of various embodiments of the present application.

[0047] It should be noted that if a component is "connected to" another component, a first component can be directly connected to a second component, and a third component can be "connected between" the first component and the second component. Conversely, if a component is "directly connected" to another component, it is understood that there are no third components between the first component and the second component.

[0048] The terms used in various embodiments of the present application are used only to describe specific embodiments and are not intended to limit various embodiments of the present application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Unless defined otherwise, all terms used herein, including technical terms and scientific terms, have the same meanings as those generally understood by those having ordinary knowledge in the art to which various embodiments of the present application belong. The terms, such as those defined in a generally used dictionary, are to be interpreted as having the same meanings as those in the context of relevant technology and will not be interpreted to have ideal or excessively formal meanings, unless clearly defined in various embodiments of the present application.

[0049] In order to make the objects, technical solutions and advantages of the present application clearer, further detailed description will be given below in combination with embodiments and drawings, the schematic embodiments and their descriptions are only used to explain the present application, and do not limit the present application.

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

[0051] As can be seen from Figure 10 , the field is squeezed to one side at this time, and such resonant cavity can also be used in actual application. However, in order to further separate the resonant cavity base mode eigenfrequency from other eigenfrequencies, the resonant cavities as shown in Figure 3 and Figure 11 are designed.

[0052] It is obvious that the distance between the frequencies of the first two modes is further separated (the eigenfrequencies of the first two modes of the circular resonant cavity are 275.9 GHz and 371 GHz respectively, and the eigenfrequencies of the circular resonant cavity with bolt hole are 277.9 GHz and 410 GHz respectively). In this way, the interference of other modes can be prevented. In addition, the tuning range of the designed circular 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 regulation structure 3, the present application adopts the same method of inserting the regulating bolt transversely into the waveguide to control the power of the passing wave instead of using an attenuator, which greatly saves the cost. The power entering the waveguide power regulation structure 3 is generally very small, generally less than 1% of the output power. Even if the reflection caused by the inserted regulating bolt causes standing wave oscillation at a place before the regulating bolt of the waveguide power regulation structure 3, since the amplitude of the caused standing wave oscillation is very small, it will not cause instability of the system. Moreover, the all-metal structure is conducive to processing and heat dissipation.

[0054] Embodiment 1

[0055] As shown in Figure 1 , the feedback oscillator structure applied to the traveling wave tube includes the waveguide structure 1, the resonant cavity frequency selection structure 2 and the waveguide power regulation 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 waveguide structure 1 is connected to the output end of traveling wave tube. Waveguide structure 1 and resonant cavity frequency selection structure 2 are connected through a coupling gap (the coupling gap connecting the first coupling gap port 14 and the second coupling gap port 21). Resonant cavity frequency selection structure 2 and waveguide power adjustment structure 3 are connected through a coupling gap (the coupling gap connecting the third coupling gap port 24 and the fourth coupling gap port 31). The output end of waveguide power adjustment structure 3 is connected to the input end of traveling wave tube.

[0057] By utilizing the frequency selection characteristics of the resonant cavity frequency selection structure 2, the resonant cavity eigenfrequency part in the clutter output from the output end of the traveling wave tube is selected, and the power is adjusted by the waveguide power adjustment structure 3 before being re-inputted to the input end of the traveling wave tube to achieve self-excited oscillation of the traveling wave tube with adjustable frequency.

[0058] In this embodiment, each structure is described in detail below:

[0059] First, waveguide structure 1

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

[0061] One end of the standard rectangular waveguide 12 is provided with a first waveguide port 11, which is connected to the output end of the traveling wave tube;

[0062] One end of the curved waveguide 13 is provided with a second waveguide port 15, which serves as the 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 sidewall of the curved waveguide 13. The first coupling slot port 14 uses electrical coupling to transmit part of the output power of the self-propelled wave tube to the resonant cavity frequency selection structure 2.

[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-tunable resonant cavity structure. The overall shape of the resonant cavity frequency selection structure 2 is a rounded rectangle. 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. The tail of the resonant cavity 22 is provided with a cylindrical first bolt hole 23. The first bolt hole 23 is used to install a vertically placed tuning bolt 25. The intrinsic frequency of the resonant cavity frequency selection structure 2 is adjusted by the depth of the tuning bolt 25 extending into (i.e., inserting) 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. 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 to transmit and couple the electromagnetic wave that has established an oscillation of the intrinsic mode frequency in the cavity 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 portion of the power output from the waveguide structure 1 to the resonant cavity 22. Electromagnetic waves that match the intrinsic frequency of the resonant cavity structure establish oscillations within the cavity, while electromagnetic waves of other frequencies are reflected or rapidly attenuated. The established resonant cavity oscillations are then coupled to the waveguide power adjustment structure 3 via 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 within the resonant cavity, resulting in a non-unique selected frequency. However, 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 electromagnetic waves 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. 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 input port of the traveling wave tube, i.e., 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 a whole 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 bolt 34 inserted 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 with each other by coupling slots, so as to realize the function of selecting the frequency of the signal transmitted from the output port of the traveling wave tube, adjusting the power and then inputting the signal to the input port of the traveling wave tube.

[0078] In the specific implementation, when the traveling wave tube just starts to work, there is no input signal, and therefore the output signal spectrum is complex and various frequency signals are mixed. The output signal of the traveling wave tube is fed into the first waveguide port, and then enters the feedback oscillator structure. Most of the power of the signal is output from the second waveguide port 15, and a small part of the power is coupled into 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 enables only the signal with the eigenfrequency of the resonant cavity to oscillate in the cavity, and signals with other frequencies are reflected or quickly attenuated. The electromagnetic wave with the eigenfrequency of the resonant cavity oscillating in the cavity continues to be transmitted through the third coupling slot port 24 and the fourth coupling slot port 31 on the right, and enters the input port of the traveling wave tube through the third waveguide port 33. This is a positive feedback, until the establishment of a steady state. In the steady state, the second waveguide port 15 outputs a large power and a pure electromagnetic wave signal with a frequency equal to the eigenfrequency of the resonant cavity. The specific process of the positive feedback is as follows:

[0079] a) The traveling wave tube has no input signal, resulting in a small output power and mixed frequency signals at the output port of the second waveguide port 15;

[0080] b) A part of the signal enters the feedback structure, is selected in frequency and adjusted in power, and then enters the input port of the traveling wave tube;

[0081] c) The input port of the traveling wave tube receives the single-frequency signal, and then amplifies the signal;

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

[0083] The process does not have a negative feedback.

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

[0085] In order to make the TWT work in the best amplification state, the transmission curve of the feedback oscillator structure should be close to the absolute value of the gain of the TWT at the frequency. When the power screw is fully released (the electromagnetic wave fully 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 TWT gain (to ensure that enough power can enter the input port of the TWT and the under-saturation condition does not occur). The following is an example:

[0086] The following is the gain of the TWT within the normal working bandwidth:

[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 TWT amplifies the power of the input signal by 32.7 dB (1862 times).

[0089] In order to make the TWT not work in the under-saturation state (the input power is less than the optimal input power), the input-output ratio of the feedback structure should be greater than the TWT gain under the condition. For example, when the frequency is 212 GHz in the above example, the TWT amplifies the power of the input signal by 32.7 dB, and the transmission of the feedback structure should be greater than -32.7 dB. Since the TWT amplification gain is different at different frequencies, the transmission of the feedback structure should be greater than the minimum value of the negative TWT gain (within the working frequency band). In the above example, the transmission of the feedback structure should be greater than -29.17 dB to ensure that the TWT does not work in the under-saturation state. In order to make the TWT not work in the over-saturation state, the adjustment screw of the waveguide power adjustment structure 3 will again reduce the transmission of the entire feedback structure, and the input power is adjusted by adjusting the screw of the waveguide power adjustment structure 3 during work to ensure that the TWT works in the best state. Since the gain of the TWT is generally more than 20 dB, generally speaking, more than 99% of the power is directly output through the waveguide structure, and only less than 1% of the power is coupled into the resonant cavity, that is, the power passing through the feedback structure is much smaller than the directly output power. In addition, the frequency range of the resonant cavity frequency modulation is generally wider than the bandwidth of the TWT, so the TWT with the feedback structure is theoretically the same as the bandwidth of the TWT 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 this structure is not suitable for pulse TWT amplifiers with a small duty cycle.

[0091] The key points of the present application are: (1) using the frequency selection characteristics of the resonant cavity, the resonant cavity eigenfrequency part in the noise wave is selected to pass through the feedback structure to form a positive feedback loop, realizing the self-excited oscillation of the adjustable frequency traveling wave tube; and it is a full metal structure, which is cheap in cost. (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 of the output part.

[0092] Example 2

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

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

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

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

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

[0098] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A feedback oscillator structure applied to a traveling wave tube, characterized by, The feedback oscillator structure comprises a waveguide structure (1), a resonant cavity frequency selection structure (2) and a waveguide power regulation structure (3) 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) through a coupling gap, the resonant cavity frequency selection structure (2) is connected to the waveguide power regulation structure (3) through a coupling gap, and the output end of the waveguide power regulation structure (3) is connected to the input end of the traveling wave tube. The resonant cavity eigenfrequency part of the output of the traveling wave tube is selected by using the frequency selection characteristic of the resonant cavity frequency selection structure (2), and the power is adjusted by the waveguide power regulation structure (3) and then input to the input end of the traveling wave tube, so that the self-excited oscillation of the traveling wave tube with adjustable frequency is realized. The waveguide structure (1) is a curved rectangular waveguide, comprising a standard rectangular waveguide (12) and a curved waveguide (13). One end of the standard rectangular waveguide (12) is provided with a first waveguide port (11), and the first waveguide port (11) is connected to the output end of the traveling wave tube. One end of the curved waveguide (13) is provided with a second waveguide port (15), and the second waveguide port (15) is used as the overall output end for outputting the output power from the traveling wave tube. A first coupling gap port (14) is formed on the side wall of the curved waveguide (13), and the first coupling gap port (14) transmits part of the output power from the traveling wave tube to the resonant cavity frequency selection structure (2) in an electrically coupled manner. The resonant cavity frequency selection structure (2) comprises a round-corner rectangular resonant cavity (22), and a cylindrical first bolt hole (23) is arranged at the tail of the resonant cavity (22) for mounting a vertically placed tuning bolt (25), and the eigenfrequency of the resonant cavity frequency selection structure (2) is adjusted by the depth of the tuning bolt (25) extending into the resonant cavity (22). A second coupling gap port (21) is arranged on one side wall of the resonant cavity frequency selection structure (2), and the second coupling gap port (21) is used for transmitting part of the output power from the waveguide structure (1) to the resonant cavity (22). A third coupling gap port (24) is arranged on the other side wall of the resonant cavity frequency selection structure (2), and the third coupling gap port (24) is used for transmitting and coupling the electromagnetic wave with the eigenmode frequency established in the cavity to the waveguide power regulation structure (3).

2. A feedback oscillator structure for a traveling wave tube according to claim 1, wherein The resonant cavity frequency selection structure (2) is an adjustable frequency resonant cavity structure, after part of the output power from the traveling wave tube is transmitted from the waveguide structure (1) to the resonant cavity structure through the coupling gap, the electromagnetic wave with the eigenfrequency of the resonant cavity structure is established in the cavity to oscillate, and the electromagnetic wave with other frequencies is reflected or attenuated; the electromagnetic wave with the eigenmode frequency established in the cavity is transmitted and coupled to the waveguide power regulation structure (3).

3. A feedback oscillator structure for a traveling wave tube according to claim 2, wherein The resonant cavity frequency selection structure (2) is a round-corner rectangular body, and the working mode of the resonant cavity frequency selection structure (2) is TE101.

4. The feedback oscillator structure for a traveling wave tube according to claim 1, wherein 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 by the resonant cavity frequency selection structure (2) as an input signal to the input port of the traveling wave tube, that is, the third waveguide port (33).

5. A feedback oscillator structure for a traveling wave tube according to claim 4, wherein The waveguide power adjustment structure (3) further comprises a cylindrical second bolt hole (32) for mounting a vertically placed adjustment bolt (34), and the depth of the adjustment bolt (34) extending into the rectangular waveguide is adjusted to adjust the power passing through.

6. The feedback oscillator structure for a traveling wave tube according to claim 1, wherein The second waveguide port (15) outputs the ratio of the output power from the traveling wave tube to the part of the power entering the resonant cavity frequency selection structure (2), which is related to the length of the coupling slot between the waveguide structure (1) and the resonant cavity frequency selection structure (2) and the length and width of the coupling slot port.

7. The feedback oscillator structure for a traveling wave tube according to claim 1, wherein The feedback oscillator structure is an all-metal structure.

8. The feedback oscillator structure for a traveling wave tube according to claim 1, wherein The feedback oscillator structure can be adjusted in size to be suitable for 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). The feedback oscillator structure is an all-metal structure. The feedback oscillator structure can be adjusted in size to be suitable for 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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