High-frequency circuit of angularly distributed multi-beam traveling-wave amplifier based on coaxial structure

Abstract

This invention discloses a high-frequency circuit for a coaxial distributed multi-beam traveling-wave amplifier. The input signal is converted from a coaxial waveguide TEM mode to a rectangular waveguide TE mode. 10 A 1-to-N power divider feeds N identical slow-wave structures angularly distributed along the centerline of the inner rod of a coaxial waveguide. The electron beam interacts with the input signal, amplifying it, and the signal is ultimately output through a power combiner. Since the coaxial waveguide has a zero cutoff frequency, transmission occurs without exciting angularly asymmetric modes. Simultaneously, the outer radius of the inner conductor and the inner radius of the outer conductor are increased, effectively increasing the device's radial dimensions, reducing the cathode load on the electron gun, and simplifying the design. Multiple slow-wave structures can be cascaded at the output of the power divider, thereby increasing the device's power.

Description

Technical Field

[0001] This invention relates to a high-frequency circuit of a coaxial-structured angular distributed multi-beam traveling wave amplifier, belonging to the field of vacuum electronic device technology. Background Technology

[0002] Semiconductor devices experienced rapid development at the end of the last century, gradually replacing vacuum electronic devices in low-frequency and low-power applications. However, in recent years, the industry has begun to recognize that vacuum electronic devices still possess irreplaceable advantages and promising development prospects in handling high power, wide bandwidth, and high frequency applications.

[0003] Among various types of vacuum electronic devices, traveling wave tubes (TWTs) are widely used in radar, communication, and detection fields due to their compact structure, moderate power, and wide bandwidth. They are commonly used as the final-stage power amplifiers in communication satellite systems. To drive the development of high-performance equipment, TWTs need to be continuously developed towards miniaturization, high power, and high frequency bands. In addition, TWT amplifiers also serve as excitation sources in many high-power devices, becoming important components for achieving wide-bandwidth, high-power, and high-efficiency electromagnetic wave transmission.

[0004] However, existing traveling wave tube amplifier technologies in the microwave, millimeter wave, and terahertz bands still have many problems:

[0005] 1) Vacuum devices operate in high-frequency bands (millimeter wave, terahertz band), and the size of the beam-wave interaction structure is small, which makes machining difficult. If high-precision machining is used, it will lead to high costs.

[0006] 2) For single-stage amplifiers, the output power level of amplifiers currently implemented in the high-frequency band needs to be improved.

[0007] 3) For multi-beam device devices, the entire device device is large in size, not compact enough, and not easy to integrate. Summary of the Invention

[0008] Objective: In order to overcome the shortcomings of the existing technology, the present invention provides a high-frequency circuit of an angular distributed multi-beam traveling wave amplifier based on a coaxial structure, which has the advantages of large structural size and easy integration.

[0009] Technical solution: To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0010] A high-frequency circuit for a coaxial distributed multi-beam traveling wave amplifier includes: N amplification units uniformly arranged along the circumferential direction, with a metal inner rod disposed between the N amplification units, where N is an integer greater than or equal to 3.

[0011] Each amplification unit includes a sector-shaped column. The front end of the sector-shaped column is configured as an input signal port, and the rear end is configured as an output signal port. Two zigzag grooves are provided on the two sides of the sector-shaped column. The front end of the zigzag groove communicates with one end of a straight groove, and the other end of the straight groove extends to the end face of the front end of the sector-shaped column. The rear end of the zigzag groove communicates with one end of the straight groove, and the other end of the straight groove extends to the end face of the rear end of the sector-shaped column. A first groove is provided on the inner surface of each end of the sector-shaped column corresponding to the straight groove, and a second groove is provided on the inner surface of the sector-shaped column corresponding to the zigzag groove.

[0012] The zigzag grooves on two adjacent sector-shaped pillars combine to form a slow-wave structure, while the straight grooves combine to form an electron beam channel. The cylindrical structure formed by the first grooves of the N sector-shaped pillars is used to place the two ends of the inner metal rod, and the cylindrical structure formed by the second grooves of the N sector-shaped pillars is used to place the middle of the inner metal rod.

[0013] As a preferred embodiment, the metal inner rod includes: a large waveguide inner rod, the two ends of which are connected to a small waveguide inner rod via transition slopes.

[0014] As a preferred embodiment, the slope of the transition slope is set to 45°.

[0015] As a preferred embodiment, the input signal is fed into the input signal port, and the amplified signal is output from the output signal port. Input and output windows are respectively installed to ensure the airtightness of the device.

[0016] As a preferred embodiment, the input signal port realizes the equal amplitude conversion of the coaxial waveguide TEM mode to N identical rectangular waveguide ports.

[0017] As a preferred embodiment, the linear grooves are configured as semi-circular grooves, and the electron injection channel formed by the combination of linear grooves is cylindrical for linear injection.

[0018] As a preferred embodiment, the slow wave structure is a tortuous waveguide structure.

[0019] As a preferred embodiment, the linear grooves are configured as rectangular grooves, and the electronic injection channel formed by the combination of linear grooves is rectangular in shape for passing through strip injection.

[0020] As a preferred embodiment, the slow-wave structure adopts an interlaced grid or sinusoidal waveguide structure.

[0021] Beneficial effects: The high-frequency circuit of the angular distributed multi-beam traveling wave amplifier based on a coaxial structure provided by this invention converts the input signal through a coaxial waveguide TEM mode to a rectangular waveguide TE mode. 10A 1-to-N power divider feeds N identical slow-wave structures angularly distributed along the centerline of the inner rod of a coaxial waveguide. Electron beams (depending on the channel shape, not limited to linear or strip beams) interact with the input signal, amplifying it. The final signal is output through a power combiner. Since the coaxial waveguide has a zero cutoff frequency, transmission occurs without exciting angularly asymmetric modes. Simultaneously, the outer radius of the inner conductor and the inner radius of the outer conductor are increased, effectively increasing the device's radial dimensions, reducing the cathode load on the electron gun, and simplifying the design. Multiple slow-wave structures can be cascaded at the output of the power divider, thereby increasing the device's power.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] Vacuum devices are used in practical production and daily life. Due to the high output power requirements, single-beam emission can easily cause device breakdown. Utilizing multiple electron beams overcomes the space charge force's limitation on the electron beam, thereby reducing the single-beam conductivity and increasing the overall conductivity. This lowers the operating voltage and focusing magnetic field, reducing the device's size and weight. Furthermore, because the fundamental mode cutoff frequency of a coaxial waveguide is zero, increasing the inner conductor radius, without generating angular asymmetric modes, not only maintains the frequency but also increases the device's lateral dimensions, reducing manufacturing costs.

[0024] In the angular cascading method of this invention, each cascaded slow-wave structure operates in the fundamental mode, and there is no mode competition due to metal isolation; unlike traditional lateral multi-cavity cascading, which may have competing modes, the angular dimension of the device of this invention is larger than the lateral dimension when the traditional TEn0 mode is operating; unlike single-cavity multi-beam, which has an uneven electric field due to the distribution of electron beam channels. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of a three-segment structure of a high-frequency circuit of a traveling-wave amplifier with angularly distributed multi-beam coaxial waveguide provided by the present invention.

[0026] Figure 2 This is a schematic diagram of a four-segment structure of a high-frequency circuit of a traveling-wave amplifier with angularly distributed multi-beam coaxial waveguide provided by the present invention.

[0027] Figure 3 This is a schematic diagram of the structure of the metal inner rod of the present invention.

[0028] Figure 4 This is a side view of the magnified unit with angular distribution.

[0029] Figure 5 It is a cross-sectional view of an enlarged unit cell with angular distribution.

[0030] Figure 6This is a single-cycle dispersion curve and coupling impedance diagram of the optimized parameters of the device of the present invention, wherein, Figure 6 (a) shows a schematic diagram of the dispersion curve for a single period. Figure 6 (b) shows a schematic diagram of the coupling impedance of the device of the present invention.

[0031] Figure 7 The transmission characteristics S of the optimized parameters of the device of this invention 21 and return loss curve S 11 Schematic diagram.

[0032] Figure 8 This is a schematic diagram showing the output power and signal spectrum of the optimized parameters of the device of the present invention at its operating center frequency. Figure 8 (a) shows a schematic diagram of the output power of the device of the present invention. Figure 8 (b) shows a schematic diagram of the signal spectrum of the output power of the device of the present invention.

[0033] Figure 9 This is a schematic diagram showing the relationship between the output power and gain of the device optimized parameters of the present invention and the frequency. Detailed Implementation

[0034] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0035] The present invention will be further described below with reference to specific embodiments.

[0036] Example 1:

[0037] This embodiment introduces a high-frequency circuit of a coaxial distributed multi-beam traveling wave amplifier, including: N amplification units uniformly arranged along the circumferential direction, with a metal inner rod 5 disposed between the N amplification units, where N is an integer greater than or equal to 3.

[0038] Each amplification unit includes a sector-shaped column. The front end of the sector-shaped column is configured as an input signal port 1, and the rear end of the sector-shaped column is configured as an output signal port 2. Two zigzag grooves 4 are respectively provided on the two sides of the sector-shaped column. The front end of the zigzag groove 4 is connected to one end of a straight groove 3, and the other end of the straight groove 3 extends to the end face of the front end of the sector-shaped column. The rear end of the zigzag groove 4 is connected to one end of the straight groove 3, and the other end of the straight groove 3 extends to the end face of the rear end of the sector-shaped column. A first groove 6 is provided on the inner surface of each end of the sector-shaped column corresponding to the straight groove 3, and a second groove 7 is provided on the inner surface of the sector-shaped column corresponding to the zigzag groove 4.

[0039] The zigzag grooves 4 on two adjacent sector-shaped pillars combine to form a slow-wave structure, and the straight grooves 3 combine to form an electron beam channel. The cylindrical structure formed by the first grooves 6 of the N sector-shaped pillars is used to place the two ends of the metal inner rod 5, and the cylindrical structure formed by the second grooves 7 of the N sector-shaped pillars is used to place the middle part of the metal inner rod 5.

[0040] Furthermore, in one embodiment, such as Figure 1 As shown, a high-frequency circuit of a coaxial distributed multi-beam traveling wave amplifier includes: three amplification units evenly arranged along the circumferential direction, with a metal inner rod 5 disposed in the middle of the three amplification units.

[0041] Each amplification unit includes a sector-shaped column. The front end of the sector-shaped column is configured as an input signal port 1, and the rear end of the sector-shaped column is configured as an output signal port 2. Two zigzag grooves 4 are respectively provided on the two sides of the sector-shaped column. The front end of the zigzag groove 4 is connected to one end of a straight groove 3, and the other end of the straight groove 3 extends to the end face of the front end of the sector-shaped column. The rear end of the zigzag groove 4 is connected to one end of the straight groove 3, and the other end of the straight groove 3 extends to the end face of the rear end of the sector-shaped column. A first groove 6 is provided on the inner surface of each end of the sector-shaped column corresponding to the straight groove 3, and a second groove 7 is provided on the inner surface of the sector-shaped column corresponding to the zigzag groove 4.

[0042] The zigzag grooves 4 on two adjacent sector-shaped pillars combine to form a slow-wave structure, and the straight grooves 3 combine to form an electron beam channel. The cylindrical structure formed by the first grooves 6 of the three sector-shaped pillars is used to place the two ends of the metal inner rod 5, and the cylindrical structure formed by the second grooves 7 of the three sector-shaped pillars is used to place the middle part of the metal inner rod 5.

[0043] Furthermore, in one embodiment, such as Figure 2 As shown, a high-frequency circuit of a coaxial distributed multi-beam traveling wave amplifier includes: four amplification units evenly arranged along the circumferential direction, with a metal inner rod 5 disposed between the four amplification units.

[0044] Each amplification unit includes a sector-shaped column. The front end of the sector-shaped column is configured as an input signal port 1, and the rear end of the sector-shaped column is configured as an output signal port 2. Two zigzag grooves 4 are respectively provided on the two sides of the sector-shaped column. The front end of the zigzag groove 4 is connected to one end of a straight groove 3, and the other end of the straight groove 3 extends to the end face of the front end of the sector-shaped column. The rear end of the zigzag groove 4 is connected to one end of the straight groove 3, and the other end of the straight groove 3 extends to the end face of the rear end of the sector-shaped column. A first groove 6 is provided on the inner surface of each end of the sector-shaped column corresponding to the straight groove 3, and a second groove 7 is provided on the inner surface of the sector-shaped column corresponding to the zigzag groove 4.

[0045] The zigzag grooves 4 on two adjacent sector-shaped pillars combine to form a slow-wave structure, and the straight grooves 3 combine to form an electron beam channel. The cylindrical structure formed by the first grooves 6 of the four sector-shaped pillars is used to place the two ends of the metal inner rod 5, and the cylindrical structure formed by the second grooves 7 of the four sector-shaped pillars is used to place the middle part of the metal inner rod 5.

[0046] Further, such as Figure 3 As shown, the metal inner rod 5 includes: a large waveguide inner rod 503, the two ends of which are connected to the small waveguide inner rod 501 through transition slopes 502 respectively.

[0047] Furthermore, the slope of the transition slope 502 is set to 45°.

[0048] Furthermore, the input signal is fed into the input signal port 1, and the amplified signal is output from the output signal port 2. Input and output windows are respectively installed to ensure the airtightness of the device.

[0049] Furthermore, the input signal port 1 realizes the equal amplitude conversion from the coaxial waveguide TEM mode to N identical rectangular waveguide (TE10 mode) ports.

[0050] Furthermore, the linear groove 3 is configured as a semi-circular groove, and the electron injection channel formed by the combination of the linear grooves 3 is cylindrical, allowing for linear injection.

[0051] Furthermore, the slow-wave structure is a tortuous waveguide structure.

[0052] Furthermore, the straight groove 3 is configured as a rectangular groove, and the electron injection channel formed by the combination of the straight grooves 3 is rectangular in shape, which can be injected through a strip.

[0053] Furthermore, the slow-wave structure adopts a periodic structure, including but not limited to interleaved grids and sinusoidal waveguides.

[0054] Example 2:

[0055] This embodiment introduces a high-frequency circuit for a coaxial-structured angularly distributed multi-beam traveling-wave amplifier. Both the input and output signal ports are coaxial waveguides, each equipped with input and output windows to ensure good vacuum. The input signal achieves energy coupling from the coaxial to N identical rectangular waveguides distributed angularly. The electron beam channel is a cylindrical channel using linear beams, or a rectangular channel using strip beams. The slow-wave structure is a zigzag waveguide, or a periodic structure such as an interlaced grid or sinusoidal waveguide. The inner metal rod has a gradually changing radius, achieving a transition from small waveguides to large waveguides to accommodate the N independent amplification units of the slow-wave structure. The N amplification units are fabricated and designed using photolithography, milling, and other techniques, and finally welded together.

[0056] Its working principle is as follows: A TEM-mode signal is input to the input port and coupled into the coaxial waveguide. A transition section converts the small coaxial waveguide to a large coaxial waveguide. Then, through power distribution within the coaxial waveguide and rectangular waveguide, the input signal is distributed to N slow-wave structure units. An electron gun, constrained by an axial guiding magnetic field, forms and emits multiple electron beams. The electron beams transfer energy to the electromagnetic wave signal, which in turn further modulates the electron beams, achieving velocity modulation and density modulation. As the modulation depth increases, the energy of the high-frequency field gradually increases. Finally, the amplified signal energy generated by the N slow-wave structures is coupled to the output terminal, ultimately outputting as a TEM-mode signal. Improvements to the slow-wave structure can increase its coupling impedance and enhance the beam-wave interaction.

[0057] Example 3:

[0058] This embodiment describes the high-frequency circuit simulation of an angular distributed multi-beam traveling wave amplifier based on a coaxial structure. The amplification units are made of oxygen-free copper, stainless steel, or composite materials. The outer radius of the high-frequency circuit composed of four amplification units is 1.5 mm.

[0059] The electron injection channel is cylindrical with a radius of 0.5 mm.

[0060] like Figure 4 , 5 As shown, the parameters of the meandering groove are: p=1.6mm, l=1.1mm, d=0.35mm, b=1.65mm, a=1.25mm, where: p is the single-cycle length of the waveguide, d is the narrow side length of the waveguide, a is the long side length of the waveguide, b is the waveguide height, and l is the half-cycle bending length of the waveguide.

[0061] Furthermore, the formula for calculating the waveguide half-cycle bending length l is as follows:

[0062]

[0063] Where z represents the distance along the z-direction of the waveguide half-cycle bend.

[0064] Furthermore, the formula for calculating the length 'a' of the long side of the waveguide is as follows:

[0065]

[0066] in, Indicates the waveguide cutoff frequency. It represents the speed of light.

[0067] The radius of the inner rod of the small waveguide is 0.9 mm, and the radius of the inner rod of the large waveguide is 1.35 mm.

[0068] The operating conditions are as follows: current is 0.3A, operating voltage is 20000V, current emission radius is 0.21mm, and input power is 0.02W.

[0069] The electric field distribution and operation process of the above-mentioned traveling wave amplifier based on coaxial waveguide with four slow-wave structures in the angular direction are as follows:

[0070] The input port receives a TEM mode signal, which propagates within the signal channel. A transition from a small coaxial waveguide to a large coaxial waveguide is achieved via a gradient section. Then, through power distribution along the coaxial to rectangular waveguide, the input signal is distributed to four slow-wave structure TEM channels. 10 In this mode, the electron gun is connected to a high potential, and the high-frequency circuit is connected to zero potential, creating a potential difference that draws out multiple electron beams, which are emitted into the electron beam channel. The electron beams interact with the signal energy (in the slow-wave structure, this is a high-frequency interaction structure). The electron beams transfer energy to the electromagnetic signal, and the signal, in turn, further modulates the electron beams, achieving velocity modulation and density modulation. As the modulation depth increases, the energy of the high-frequency field gradually increases. Finally, the signal energy is coupled into a four-in-one power combiner, and then coupled to the output signal port via a coaxial waveguide at TE. 10 The output mode yields an amplified signal. By adjusting the structure and size of the slow-wave structure, as well as the size of the electron beam channel, the coupling impedance and frequency passband are modified to design a device with high frequency, high power, and wide bandwidth to meet specific requirements. A collector is added at the output end to collect waste electrons. Water cooling and air cooling are used to ensure the normal and stable operation of the device unit. The device is fabricated using photolithography and milling techniques; finally, it is welded to the output window to ensure good sealing performance.

[0071] Figure 6 It involves optimizing the dispersion curve and coupling impedance of a single cycle. Figure 6(a) indicates that the passband frequency of the operating mode is 60.3 GHz to 74.2 GHz, and the device operates at the +1st harmonic (2π to 3π). The cutoff frequency is determined by the length of 'a'. Figure 6 (b) represents the pince impedance at the center of the electron beam channel within the passband. Its value is greater than 10Ω in the operating frequency range. The pince impedance indicates the degree of interaction between the electron beam and the high-frequency field. The values ​​of the two parameters are determined by the single-cycle structure parameters.

[0072] Figure 7 These are the optimized S-parameter results for the device of this invention. The solid line represents the insertion loss S. 21 Within the operating range, the loss is greater than -3dB. The dashed line represents the return loss S. 11 The values ​​are all below -5dB within the operating range.

[0073] Figure 8 This is the particle simulation result under optimized parameters of the device of the present invention. Figure 8 (a) The figure shows the power signal diagram of the output port (Port signal) after 1.4ns of stable operation. The output power is 4.5W (the input power is 20mW) and the corresponding gain is 23.58dB. Figure 8 (b) shows the result of the Fourier transform of the output signal. As can be seen from the figure, the operating frequency is 66 GHz, the spectrum is single, and there are no spurious modes.

[0074] Figure 9 This is the curve of output power versus frequency and the corresponding gain result under the optimized parameters of the device of this invention, with an input power of 20mW.

[0075] It should be noted that the size and shape of the electron beam channel, as well as the parameters of the slow wave structure, can be designed according to actual engineering needs. These parameters will affect the coupling impedance, the frequency band, and thus the device performance and application range.

[0076] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high-frequency circuit based on a coaxial structure angularly distributed multi-beam traveling-wave amplifier, characterized in that: include: N magnification units are evenly arranged along the circumference, and a metal inner rod is set in the middle of the N magnification units, where N is an integer greater than or equal to 3; Each amplification unit includes: a sector-shaped column, the front end of which is configured as an input signal port, and the rear end of which is configured as an output signal port. Two zigzag grooves are respectively provided on the two sides of the sector-shaped column. A first straight groove is provided at the front end of the zigzag groove, one end of which is connected to the front end of the zigzag groove, and the other end of which extends to the end face of the front end of the sector-shaped column. A second straight groove is provided at the rear end of the zigzag groove, one end of which is connected to the rear end of the zigzag groove, and the other end of which extends to the end face of the rear end of the sector-shaped column. The inner surfaces of the two ends of the sector-shaped column corresponding to the first and second straight grooves are respectively provided with a first groove, and the inner surface of the sector-shaped column corresponding to the zigzag groove is provided with a second groove. The zigzag grooves on two adjacent sector-shaped pillars combine to form a slow-wave structure, and the first straight groove and the second straight groove on two adjacent sector-shaped pillars combine to form an electron injection channel; the cylindrical structure formed by the first grooves of N sector-shaped pillars is used to place the two ends of the metal inner rod, and the cylindrical structure formed by the second grooves of N sector-shaped pillars is used to place the middle part of the metal inner rod.

2. The high-frequency circuit of the angular distributed multi-beam traveling-wave amplifier based on a coaxial structure according to claim 1, characterized in that: The metal inner rod includes a large waveguide inner rod, the two ends of which are connected to a small waveguide inner rod via transition slopes.

3. The high-frequency circuit of the angular distributed multi-beam traveling wave amplifier based on a coaxial structure according to claim 2, characterized in that: The slope of the transition slope is set to 45°.

4. The high-frequency circuit of the angular distributed multi-beam traveling-wave amplifier based on a coaxial structure according to claim 1, characterized in that: The input signal is fed into the input signal port, and the output signal port outputs the amplified signal, and input and output windows are respectively installed.

5. The high-frequency circuit of the angular distributed multi-beam traveling-wave amplifier based on a coaxial structure according to claim 1, characterized in that: The input signal port enables equal-amplitude conversion of the coaxial waveguide TEM mode to N identical rectangular waveguide ports.

6. The high-frequency circuit of the angular distributed multi-beam traveling-wave amplifier based on a coaxial structure according to claim 1, characterized in that: Both the first and second linear grooves are semi-circular grooves, and the electronic injection channel formed by the combination of the first and second linear grooves is cylindrical for linear injection.

7. The high-frequency circuit of the angular distributed multi-beam traveling wave amplifier based on a coaxial structure according to claim 1, characterized in that: The slow-wave structure is a tortuous waveguide structure, an interlaced grid, or a sinusoidal waveguide structure.

8. The high-frequency circuit of the angular distributed multi-beam traveling-wave amplifier based on a coaxial structure according to claim 1, characterized in that: Both the first and second straight grooves are rectangular grooves, and the electronic injection channel formed by the combination of the first and second straight grooves is rectangular in shape for passing through a strip injection.

9. The high-frequency circuit of the angular distributed multi-beam traveling-wave amplifier based on a coaxial structure according to claim 1, characterized in that: The formula for calculating the waveguide half-cycle bending length l of the slow-wave structure is as follows: ; Where z represents the distance along the z-direction of the waveguide's half-cycle bending, and b is the waveguide height.

10. The high-frequency circuit of the angular distributed multi-beam traveling-wave amplifier based on a coaxial structure according to claim 1, characterized in that: The formula for calculating the waveguide long side length 'a' of the slow-wave structure is as follows: ; in, Indicates the waveguide cutoff frequency. It represents the speed of light.

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