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

Abstract

The invention discloses a high-frequency circuit of an angular distribution type multi-beam traveling wave amplifier based on a coaxial structure, which is characterized in that an input signal is fed into N same slow wave structures which are angularly distributed along the positive center line of a coaxial waveguide inner rod through a one-to-N power divider for converting a coaxial waveguide TEM mode into a rectangular waveguide TE10 mode, and electron beams and the input signal generate beam-wave interaction; and finally, the signal is output through the power combiner. The cut-off frequency of the coaxial waveguide is zero, transmission is carried out on the premise of not exciting an angular asymmetric mode, and the outer radius of the coaxial inner conductor and the inner radius of the outer conductor are increased, so that the radial size of the device is effectively increased, the cathode load of the electron gun is reduced, and the design difficulty is reduced. Cascade connection of a plurality of slow wave structures can be realized through the output end of the power divider, so that the power of the device is increased.

Description

Technical Field

[0001] The invention relates to a high-frequency circuit of an angularly distributed multi-beam traveling wave amplifier based on a coaxial structure, and belongs to the technical field of vacuum electronic devices. Background Art

[0002] Semiconductor devices have developed rapidly 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 realize that vacuum electronic devices still have irreplaceable advantages and development prospects in terms of processing high power, wide bandwidth and high frequency.

[0003] Among various types of vacuum electronic devices, traveling wave tubes are widely used in radar, communication, detection and other fields due to their compact structure, moderate power and wide bandwidth. They are often used as the final power amplifier of communication satellite systems. In order to promote the development of high-performance equipment, traveling wave tubes need to continue to develop in the direction of miniaturization, high power and high frequency band. In addition, traveling wave tube amplifiers also act as excitation sources in many high-power devices, becoming an important device for achieving broadband, high-power and high-efficiency emission of electromagnetic waves.

[0004] However, there are still many problems with the existing microwave, millimeter wave, terahertz and other band traveling wave tube amplifier technologies:

[0005] 1) Vacuum devices work in high-frequency bands (millimeter wave and terahertz band), and the size of the injection wave interaction structure is small, which makes mechanical processing difficult. If high-precision processing is used, the cost will be high.

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

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

[0008] Purpose: In order to overcome the deficiencies in the prior art, the present invention provides a high-frequency circuit of an angularly 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:

[0010] A high-frequency circuit of an angularly distributed multi-beam traveling wave amplifier based on a coaxial structure comprises: N amplifying units evenly arranged along the circumferential direction, a metal inner rod is arranged in the middle of the N amplifying units, wherein 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 set as an input signal port, the rear end of the sector-shaped column is set as an output signal port, and the two side surfaces of the sector-shaped column are respectively provided with zigzag grooves, the front end of the zigzag groove is connected with one end of the straight groove, and the other end of the straight groove extends to the end surface of the front end of the sector-shaped column, the rear end of the zigzag groove is connected with one end of the straight groove, and the other end of the straight groove extends to the end surface of the rear end of the sector-shaped column. The inner surfaces of the two ends of the sector-shaped column corresponding to the straight groove are respectively provided with first grooves, and the inner surface of the sector-shaped column corresponding to the zigzag groove is provided with second grooves.

[0012] The zigzag grooves on two adjacent sector-shaped cylinders are combined into a slow wave structure, and the straight grooves are combined into an electron injection channel. The cylindrical structure formed by the first grooves of N sector-shaped cylinders 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 cylinders is used to place the middle of the metal inner rod.

[0013] As a preferred solution, the metal inner rod comprises: a large waveguide inner rod, and both ends of the large waveguide inner rod are connected to the small waveguide inner rod through transition slopes.

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

[0015] As a preferred solution, the input signal port is fed with an input signal, the output signal port outputs an amplified signal, and input and output windows are respectively provided to ensure the airtightness of the device.

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

[0017] As a preferred solution, the linear grooves are configured as semicircular grooves, and the electron injection channel formed by the linear grooves is cylindrical and is used for passing the linear injection.

[0018] As a preferred solution, the slow-wave structure is a meandering waveguide structure.

[0019] As a preferred solution, the linear grooves are configured as rectangular grooves, and the electron injection channel formed by the linear grooves is rectangular in shape and is used for passing the strip injection.

[0020] As a preferred solution, the slow-wave structure adopts a staggered grating or a sinusoidal waveguide structure.

[0021] Beneficial effect: The high-frequency circuit of the angular distributed multi-beam traveling wave amplifier based on the coaxial structure provided by the present invention converts the input signal into the rectangular waveguide TE mode through the coaxial waveguide TEM mode. 10The one-to-N power divider of the mode is fed into N identical slow-wave structures distributed angularly along the center line of the inner rod of the coaxial waveguide. The electron beam (depending on the channel shape, not limited to linear beam and strip beam) interacts with the input signal to achieve amplification, and finally outputs the signal through the power synthesizer. Since the cutoff frequency of the coaxial waveguide is zero, transmission is carried out without exciting the angular asymmetric mode. At the same time, the outer radius of the coaxial inner conductor and the inner radius of the outer conductor are increased, thereby effectively increasing the radial size of the device, reducing the cathode load of the electron gun, and reducing the design difficulty. The cascade of multiple slow-wave structures can be achieved through the output end of the power divider, thereby increasing the power of the device.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] Vacuum devices are used in actual production and life. Due to the high requirements for output power, single-beam emission can easily cause device breakdown. Multi-electron beams are fully utilized to break through the limitation of space charge force on electron beams, thereby reducing the single-beam conductivity and increasing the total conductivity, reducing its operating voltage and focusing magnetic field, and reducing its volume and weight. In addition, due to the zero cutoff frequency of the fundamental mode of the coaxial waveguide, under the premise of not generating angular asymmetric modes, increasing the radius of the inner conductor can not only keep the frequency unchanged, but also increase the lateral size of the device and reduce the processing cost.

[0024] In the angular cascade mode of the present invention, the slow-wave structure of each cascade works in the fundamental mode, and there is no mode competition through metal partition; it is different from the traditional lateral multi-cavity cascade, which has the possibility of competition mode. The angular size of the device of the present invention is larger than the lateral size when the traditional TEn0 mode works; it is different from the single-cavity multi-injection, which has an uneven electric field due to the distribution of electron injection channels. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The present invention provides a three-section structural schematic diagram of a high-frequency circuit of a coaxial waveguide angularly distributed multi-injection traveling wave amplifier.

[0026] Figure 2 The present invention provides a four-section structural schematic diagram of a high-frequency circuit of a coaxial waveguide angularly distributed multi-injection traveling wave amplifier.

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

[0028] Figure 4 is a side view of the angularly distributed amplification unit.

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

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

[0031] Figure 7 is the transmission characteristic S of the device optimization parameters of the present invention 21 And the return loss curve S 11 Schematic diagram.

[0032] Figure 8 Schematic diagram of the output power and signal spectrum of the working center frequency of the device with optimized parameters of the present invention, wherein: Figure 8 (a) is a schematic diagram showing the output power of the device of the present invention. Figure 8 (b) is a schematic diagram showing the signal spectrum of the output power of the device of the present invention.

[0033] Fig. 9 It is a schematic diagram of the relationship between the output power and gain of the optimized parameters of the device of the present invention and the frequency. DETAILED DESCRIPTION

[0034] The following is a clear and complete description of the technical solutions in the examples of the present invention in conjunction with the accompanying drawings in the examples of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the protection scope of the present invention.

[0035] The present invention will be further described below in conjunction with specific embodiments.

[0036] Embodiment 1:

[0037] This embodiment introduces a high-frequency circuit of an angularly distributed multi-beam traveling wave amplifier based on a coaxial structure, comprising: N amplifying units evenly arranged along the circumferential direction, a metal inner rod 5 is arranged in the middle of the N amplifying units, wherein 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 set as an input signal port 1, the rear end of the sector-shaped column is set as an output signal port 2, and the two sides of the sector-shaped column are respectively provided with a zigzag groove 4, the front end of the zigzag groove 4 is connected with one end of the 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, and the rear end of the zigzag groove 4 is connected with 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. The inner surfaces of the two ends of the sector-shaped column corresponding to the straight groove 3 are respectively provided with a first groove 6, and the inner surface of the sector-shaped column corresponding to the zigzag groove 4 is provided with a second groove 7.

[0039] The zigzag grooves 4 on two adjacent sector-shaped cylinders are combined into a slow wave structure, and the straight grooves 3 are combined into an electron injection channel. The cylindrical structure formed by the first grooves 6 of the N sector-shaped cylinders 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 cylinders is used to place the middle part of the metal inner rod 5.

[0040] Further, an embodiment, such as Figure 1 As shown, a high-frequency circuit of an angularly distributed multi-beam traveling wave amplifier based on a coaxial structure comprises: three amplifying units evenly arranged along the circumferential direction, and a metal inner rod 5 is arranged between the three amplifying units.

[0041] Each amplification unit includes: a sector-shaped column, the front end of the sector-shaped column is set as an input signal port 1, the rear end of the sector-shaped column is set as an output signal port 2, and the two sides of the sector-shaped column are respectively provided with a zigzag groove 4, the front end of the zigzag groove 4 is connected with one end of the 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, and the rear end of the zigzag groove 4 is connected with 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. The inner surfaces of the two ends of the sector-shaped column corresponding to the straight groove 3 are respectively provided with a first groove 6, and the inner surface of the sector-shaped column corresponding to the zigzag groove 4 is provided with a second groove 7.

[0042] The zigzag grooves 4 on two adjacent sector-shaped cylinders are combined into a slow wave structure, and the straight grooves 3 are combined into an electron injection channel. The cylindrical structure formed by the first grooves 6 of the three sector-shaped cylinders 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 cylinders is used to place the middle part of the metal inner rod 5.

[0043] Further, an embodiment, such as Figure 2 As shown, a high-frequency circuit of an angularly distributed multi-beam traveling wave amplifier based on a coaxial structure comprises: four amplifying units evenly arranged along the circumferential direction, and a metal inner rod 5 is arranged between the four amplifying units.

[0044] Each amplification unit includes: a sector-shaped column, the front end of the sector-shaped column is set as an input signal port 1, the rear end of the sector-shaped column is set as an output signal port 2, and the two sides of the sector-shaped column are respectively provided with a zigzag groove 4, the front end of the zigzag groove 4 is connected with one end of the 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, and the rear end of the zigzag groove 4 is connected with 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. The inner surfaces of the two ends of the sector-shaped column corresponding to the straight groove 3 are respectively provided with a first groove 6, and the inner surface of the sector-shaped column corresponding to the zigzag groove 4 is provided with a second groove 7.

[0045] The zigzag grooves 4 on two adjacent sector-shaped columns are combined into a slow wave structure, and the straight grooves 3 are combined into an electron injection channel. The cylindrical structure formed by the first grooves 6 of the four sector-shaped columns 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 columns 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 comprises: a large waveguide inner rod 503 , and two ends of the large waveguide inner rod 503 are connected to the small waveguide inner rod 501 through transition slopes 502 .

[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 output signal port 2 outputs the amplified signal, and input and output windows are respectively installed to ensure the airtightness of the device.

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

[0050] Furthermore, the linear grooves 3 are configured as semicircular grooves, and the electron injection channel formed by the linear grooves 3 is cylindrical and can pass through linear injection.

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

[0052] Furthermore, the linear grooves 3 are configured as rectangular grooves, and the electron injection channel formed by the linear grooves 3 is in a rectangular shape, through which strip injection can be performed.

[0053] Furthermore, the slow-wave structure adopts a periodic structure, including but not limited to a staggered grating and a sinusoidal waveguide.

[0054] Embodiment 2:

[0055] This embodiment introduces a high-frequency circuit of an angularly distributed multi-beam traveling wave amplifier based on a coaxial structure, wherein the input signal port and the output signal port are both coaxial waveguides, respectively equipped with input and output windows to ensure a good vacuum degree; the input signal realizes energy coupling from the coaxial to N identical rectangular waveguides distributed angularly; the electron injection channel is a cylindrical channel, using linear injection, or a rectangular channel, using strip injection; the slow-wave structure is a zigzag waveguide, or a periodic structure such as a staggered grating or a sinusoidal waveguide; the metal inner rod has a gradual radius change to realize the transition from a small waveguide to a large waveguide, so as to adapt to the independent amplification units of the N slow-wave structures; the N amplification units are processed and designed by photolithography, milling and other technologies; and finally, they are welded and synthesized.

[0056] Its working principle is as follows: TEM mode signal is input at the input port, the signal is coupled into the coaxial waveguide, and the conversion from small coaxial waveguide to large coaxial waveguide is realized through the gradient section. Then, the input signal is distributed to N slow-wave structure units through the power distribution from coaxial waveguide to rectangular waveguide. Under the constraint of the axial guide magnetic field, the matching electron gun forms a multi-electron beam and emits it. The electron beam transfers energy to the electromagnetic wave signal, and the signal in turn further modulates the electron beam to realize speed 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 N slow-wave structures is coupled to the output end and finally output in TEM mode. By improving the slow-wave structure, its coupling impedance can be increased and the degree of beam-wave interaction can be increased.

[0057] Embodiment 3:

[0058] This embodiment introduces a high-frequency circuit simulation of an angularly distributed multi-beam traveling wave amplifier based on a coaxial structure, wherein the amplification unit is made of oxygen-free copper, stainless steel or synthetic materials, etc.; the outer radius of the high-frequency circuit composed of four amplification units is 1.5 mm.

[0059] The electron injection channel is configured to be cylindrical, wherein the radius is 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 calculation formula of the waveguide half-period bending length l is as follows:

[0062]

[0063] Wherein, z represents the distance of the waveguide half-period bending along the z direction.

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

[0065]

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

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

[0068] The working condition parameters of the given parameters are: current is 0.3A, working voltage is 20000V, current emission surface radius is 0.21mm, and input power is 0.02W.

[0069] The electric field distribution working process of the above-mentioned coaxial waveguide-based traveling wave amplifier having four slow-wave structures distributed angularly is as follows:

[0070] The input TEM mode signal at the input port is transmitted in the signal channel, and the conversion from the small coaxial waveguide to the large coaxial waveguide is realized through the gradient section. Then, the input signal is distributed to the TE of the four slow-wave structures through the power distribution of the coaxial rectangular waveguide. 10 mode, the electron gun is connected to high potential, and the high-frequency circuit is connected to zero potential, forming a potential difference, pulling out multiple electron beams and emitting them into the electron beam channel. The electron beam interacts with the signal energy (the slow-wave structure is a high-frequency interaction structure), and the electron beam transfers energy to the electromagnetic wave signal, which in turn further modulates the electron beam to achieve speed modulation and density modulation. As the modulation depth increases, the energy of the high-frequency field gradually increases. Finally, the signal energy is coupled to the four-in-one power synthesizer, and then coupled to the output signal port through the coaxial waveguide to form a TE 10 The mode output is used to obtain the amplified signal. By adjusting the structure and size of the slow-wave structure, the size of the electron injection channel, etc., the coupling impedance and frequency passband are adjusted to design devices with high frequency, high power, wide bandwidth and other characteristics to meet the needs. A collector is provided at the output end to collect the waste electrons. The normal and stable operation of the device unit is ensured by cooling measures such as water cooling and air cooling. The device is processed and designed by photolithography, milling and other technologies; finally, it is welded and synthesized with the output window to ensure good sealing performance.

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

[0072] Figure 7 It is the S parameter result of the device optimization of the present invention. The solid line represents the insertion loss S 21 , which is greater than -3dB within the working range. The dotted line indicates the return loss S 11 , all below -5dB within the working range.

[0073] Figure 8 This is the particle simulation result under the optimized parameters of the device of the present invention. Figure 8 (a) shows the power signal diagram of the output port (Port signal) working stably for 1.4ns, the output power is 4.5W, (the input power is 20mW) and the corresponding gain is 23.58dB; Figure 8 (b) is the result of Fourier transform of the output signal. It can be seen from the figure that the operating frequency is 66 GHz, the spectrum is single, and there is no noise mode.

[0074] Fig. 9 It is a curve showing the output power changing with frequency and the corresponding gain result under the optimized parameters of the device of the present invention at an input power of 20 mW.

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

[0076] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A high-frequency circuit of an angularly distributed multi-beam traveling wave amplifier based on a coaxial structure, characterized in that: include: N amplifying units are evenly arranged along the circumferential direction, and a metal inner rod is arranged in the middle of the N amplifying units, wherein N is an integer greater than or equal to 3; Wherein, each amplification unit comprises: a fan-shaped column, the front end of the fan-shaped column is set as an input signal port, the rear end of the fan-shaped column is set as an output signal port, the two side surfaces of the fan-shaped column are respectively provided with zigzag grooves, the front end of the zigzag groove is connected with one end of the straight groove, and the other end of the straight groove extends to the end face of the front end of the fan-shaped column, the rear end of the zigzag groove is connected 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 fan-shaped column; the inner surfaces of the two ends of the fan-shaped column corresponding to the straight groove are respectively provided with first grooves, and the inner surface of the fan-shaped column corresponding to the zigzag groove 4 is provided with a second groove; The zigzag grooves on two adjacent fan-shaped cylinders are combined into a slow-wave structure, and the straight grooves are combined into an electron injection channel; the cylindrical structure formed by the first grooves of N fan-shaped cylinders is used to place the two ends of the metal inner rod, and the cylindrical structure formed by the second grooves of N fan-shaped cylinders is used to place the middle part of the metal inner rod.

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

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

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

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

6. The high frequency circuit of the angularly distributed multi-beam traveling wave amplifier based on the coaxial structure according to claim 1, characterized in that: The linear grooves are configured as semicircular grooves, and the electron injection channel formed by the linear grooves is cylindrical and is used for passing the linear injection.

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

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

9. The high frequency circuit of the angularly distributed multi-beam traveling wave amplifier based on the coaxial structure according to claim 1, characterized in that: The calculation formula of the waveguide half-period bending length l of the slow-wave structure is as follows: ; Wherein, z represents the distance of the half-period bending of the waveguide along the z direction.

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

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