Parallel dual spherical cavity passive pulse compressor

Abstract

The application discloses a parallel double-spherical resonant cavity passive pulse compressor and belongs to the technical field of high-power microwave pulse compression. The device comprises a dual-polarization mode coupler, two spherical resonant cavities and two coupling transition structures. The dual-polarization mode coupler comprises a T-shaped joint, two standard circular waveguides and a symmetrical structure. The spherical resonant cavities are coupled with the standard circular waveguides of the dual-polarization mode coupler through the coupling transition structures. Two identical spherical resonant cavities are arranged in parallel on the upper and lower parts of the dual-polarization mode coupler, so that the quality factor of the whole pulse compressor is improved, and the peak power gain of pulse compression is obviously improved.

Description

Technical Field

[0001] This invention pertains to high-power microwave pulse compression technology, specifically relating to a parallel dual-sphere resonant cavity passive pulse compressor. Background Technology

[0002] To achieve higher power, besides power combining, pulse compression is another method. The main principle of pulse compression technology is to first input a microwave pulse into an energy storage device, and then rapidly extract the energy stored in the device to achieve a high-power microwave pulse output. Pulse compression can increase the success rate of compressing long, low-power microwave pulses into short microwave pulses several times or even tens of times. Pulse compression is mainly divided into two types: passive pulse compression, which mainly uses signal inversion to release energy from the energy storage device (primarily used in accelerators); and active pulse compression, which mainly uses changes in the microwave parameters of the energy storage device, such as coupling, to release energy (commonly used in high-power microwave (HPM) applications).

[0003] The earliest passive pulse compressor was the SLED pulse compressor proposed by SLAC in 1973. This pulse compressor consists of two identical high-quality factor resonant cavities and a 3dB coupler. Its principle is that a microwave pulse is input from one port of the 3dB coupler. After part of the energy enters the resonant cavity, a microwave field is established and stored in the resonant cavity. If the signal is inverted before the input pulse ends, the energy in the resonant cavity will be superimposed with the inverted signal and output as a microwave pulse with a very high peak power from the other port of the 3dB coupler.

[0004] Subsequently, the development of SLED pulse compressors has focused on higher efficiency, higher peak power gain, and compact design. In 2018, Wang Ping of Tsinghua University proposed an S-band SLED pulse compressor based on TE... 112 A compact SLED pulse compressor with a spherical resonant cavity was developed and used in the dual-speed tuner experimental platform at Tsinghua University. This device replaces the 3dB coupler in traditional SLED pulse compressors with a three-port dual-mode circularly polarized coupler, and its key feature is that it requires only one resonant cavity, resulting in a very compact structure.

[0005] In a pulse compressor, a higher quality factor in the resonant cavity results in a stronger energy storage capacity. The quality factor of a spherical resonant cavity is related to the radius of the sphere; the larger the radius, the higher the quality factor. If a higher-performance mode, such as TE, is used in the spherical resonant cavity... 113 While a higher resonant cavity quality factor is desirable, a larger cavity radius also results in a larger volume. Furthermore, as the cavity volume increases, the number of modes increases, leading to greater mode competition. This means the gain of the pulse compressor doesn't increase significantly; instead, the entire compression system becomes too large and its efficiency decreases. Summary of the Invention

[0006] To address the shortcomings of existing passive pulse compression technologies, this invention provides a parallel dual-sphere resonant cavity passive pulse compressor. This method involves connecting an identical spherical resonant cavity in parallel below a dual-polarization mode coupler. By adjusting the lengths of the upper and lower circular waveguides, the length difference between the two waveguides is made to be 5 / 8λ. g The power gain is an integer multiple of the value. Compared to pulse compressors with a single resonant cavity, this method can significantly improve the peak power gain and efficiency of pulse compression.

[0007] The technical solution adopted in this invention is as follows:

[0008] A parallel dual-sphere resonant cavity passive pulse compressor is characterized in that the compressor comprises: a dual-polarization mode coupler, two sphere resonant cavities, and two coupling transition structures.

[0009] The dual-polarization mode coupler includes a T-junction, two standard circular waveguides, and a symmetrical structure. The T-junction is composed of two standard rectangular waveguides and one overmode waveguide. The two standard circular waveguides are symmetrically arranged on the E-plane of the overmode waveguide. The symmetrical structure, used to suppress clutter modes, is obtained by chamfering the corners on both sides and the middle of the rectangular waveguide. Its input end is connected to the output end of the overmode waveguide, and the dimensions of the connection surface are the same.

[0010] The coupling transition structure consists of a transition section with a gradually changing radius and a coupling circular waveguide section. The radius of the coupling circular waveguide section is smaller than that of the standard circular waveguide. The transition section is used to smoothly connect the standard circular waveguide to the coupling circular waveguide section.

[0011] The spherical resonant cavity is coupled to the standard circular waveguide through the coupling transition structure.

[0012] Furthermore, the length difference between the two standard circular waveguides is 5 / 8λ. g Integer multiples of λ g Indicates the operating wavelength.

[0013] Furthermore, the position of the standard circular waveguide is: 1 / 4λ distance from the connection surface between the standard rectangular waveguide and the overmode waveguide. g At integer multiples of .

[0014] Furthermore, the T-junction has a chamfer in the middle to optimize the isolation between the input and output ends; the H-planes of the two standard rectangular waveguides have identical matching structures to optimize the reflection coefficient.

[0015] Furthermore, the position of the matching structure is: 1 / 4λ distance from the connection surface between the standard rectangular waveguide and the overmode waveguide. g At integer multiples of .

[0016] Furthermore, the width of the overmode waveguide is between λ and λ. g ~1.5λ g between.

[0017] In a T-junction, one standard rectangular waveguide serves as the input terminal, and the other standard rectangular waveguide serves as the output terminal; TE is input from the input terminal. 10 The mode is coupled out in the overmode waveguide. 10 Model and TE 20 The mode is then transmitted to a standard circular waveguide and converted into two orthogonal TE signals. 11 The mode, after being coupled through a transition structure, excites the TE in the spherical resonant cavity. 112 The energy stored in the spherical resonant cavity is finally output as TE at the output terminal. 10 mold.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] (1) The present invention improves the quality factor of the entire pulse compressor by connecting two identical spherical resonant cavities in parallel between the upper and lower standard circular waveguides of the dual polarization mode coupler, thereby significantly improving the peak power gain of pulse compression.

[0020] (2) The passive pulse compressor of the present invention contains two resonant cavities, and the distance difference between the two resonant cavities and the overmode waveguide is 5 / 8λ. g Integer multiples of this value can effectively suppress stray modes in the resonant cavity, increase mode spacing, and thus improve device efficiency.

[0021] (3) The output microwave pulse attenuation of the present invention is slower than that of the output pulse attenuation of a single resonant cavity pulse compressor, and the pulse width is wider, thus significantly improving the compression efficiency.

[0022] (4) Compared with the use of higher modes such as TE, the present invention 113 Compared to a spherical resonant cavity, a pulse compressor is smaller and more compact. Attached Figure Description

[0023] Figure 1 This is a structural diagram of a parallel dual-resonant cavity pulse compressor in an embodiment of the present invention.

[0024] Figure 2 A schematic diagram of a dual-polarization mode coupler structure in an embodiment of the present invention.

[0025] Figure 3 TE is a spherical resonant cavity 112 Model field distribution diagram.

[0026] Figure 4This invention presents a comparison of the S-parameters of a single-cavity pulse compressor and a parallel dual-cavity pulse compressor in an embodiment of the invention. (a) is an S-parameter curve of the single-cavity pulse compressor; (b) is an S-parameter curve of the parallel dual-cavity pulse compressor.

[0027] Figure 5 This is a comparison of the input and output signals of a single-cavity pulse compressor and a parallel dual-cavity pulse compressor in an embodiment of the present invention. (a) Comparison of the input and output signals of the single-cavity pulse compressor; (b) Comparison of the input and output signals of the parallel dual-cavity pulse compressor.

[0028] Among them: 1. Standard rectangular waveguide; 2. Overmode waveguide; 3. Standard circular waveguide; 4. Symmetrical structure; 5. Coupled transition structure; 6. Spherical resonant cavity; 7. Matching structure. Detailed Implementation

[0029] To more clearly illustrate the purpose, features, and advantages of the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is a complete S-band (2.458MHz) parallel dual-resonant cavity pulse compressor.

[0030] like Figure 1 , Figure 2 As shown, the standard rectangular waveguide in this dual-polarization mode coupler is a BJ22 (a = 109.2 mm, b = 54.6 mm), and the overmode waveguide contains two modes: TE. 10 and TE 20 Therefore, the wide side of the overmode waveguide should be between λ and λ. g ~1.5λ g In this embodiment, the length is 143mm. To suppress higher-order modes, the length of the overmode waveguide is appropriately increased so that higher-order modes attenuate during transmission; in this embodiment, it is 164mm. The standard circular waveguide used is the standard circular waveguide WC385 (R = 48.93mm), and its position is 3 / 4λ away from the interface between the standard rectangular waveguide and the overmode waveguide. g Adding a symmetrical structure at the end of the overmode waveguide can suppress clutter modes and enhance mode conversion between the overmode waveguide and the standard circular waveguide. Matching structures are added to the input and output ports of the T-junction to reduce reflections; the matching structure is located at a distance of 1 / 4λ from the interface between the standard rectangular waveguide and the overmode waveguide. g Place.

[0031] like Figure 3 The radius of the spherical resonant cavity is 149.3 mm, and the resonant cavity mode is TE. 112The mode has a quality factor of 85000. The coupling transition structure between the resonant cavity and the standard circular waveguide consists of a transition section with a gradually changing radius and a circular waveguide section. The size of the coupling aperture affects the coupling degree, thereby affecting the power gain of the pulse compressor. Therefore, it is necessary to optimize and adjust the size of the coupling aperture to be within a suitable range. In this embodiment, the radius of the coupling aperture, i.e., the radius of the coupling circular waveguide section, is 30 mm.

[0032] In a complete parallel dual-cavity pulse compressor, the lengths of the upper and lower standard circular waveguides are adjusted to differ by 5 / 8λ. g The S-parameters of the parallel dual-resonant cavity pulse compressor are as follows: Figure 4 As shown, compared to a single-cavity pulse compressor, a parallel dual-cavity pulse compressor has fewer miscellaneous modes. Figure 4 (b) It can be seen that S 21 Within the 2.4-2.5 GHz range, there is only one peak, indicating that there is only one operating mode within this 100 MHz bandwidth, and the mode interval has increased.

[0033] like Figure 5 (a) When the input signal pulse width is 2µs and it is inverted at 1.4µs, the peak power gain of the single-cavity pulse compressor is 6.49, the output signal pulse width is approximately 200ns, the compression ratio is 10, and the efficiency is approximately 22.6%. Figure 5 As shown in (b), under the same signal excitation, the peak power gain of the parallel dual-resonant cavity pulse compressor is increased to 7.52, the pulse width of the output signal is approximately 540 ns, the compression ratio is 3.7, and the efficiency is increased to 52.43%. Through comparison, the parallel dual-resonant cavity pulse compressor can significantly improve the peak power gain and efficiency. Furthermore, compared to using higher-order modes such as TE... 113 The single-cavity pulse compressor of the mode is smaller, has better mode suppression, and is easier to manufacture.

Claims

1. A parallel dual-sphere resonant cavity passive pulse compressor, characterized in that, The compressor includes: a dual-polarization mode coupler, two spherical resonant cavities, and two coupling transition structures; The dual-polarization mode coupler includes a T-junction, two standard circular waveguides, and a symmetrical structure. The T-junction is composed of two standard rectangular waveguides and one overmode waveguide. The two standard circular waveguides are symmetrically arranged on the E-plane of the overmode waveguide. The symmetrical structure, used to suppress unwanted modes, is obtained by chamfering the corners on both sides and the middle of the rectangular waveguide. Its input end is connected to the output end of the overmode waveguide, and the dimensions of the connection surfaces are the same. The coupling transition structure consists of a transition section with a gradually changing radius and a coupling circular waveguide section. The radius of the coupling circular waveguide section is smaller than that of the standard circular waveguide. The transition section is used to smoothly connect the standard circular waveguide to the coupling circular waveguide section. The spherical resonant cavity is coupled to the standard circular waveguide through the coupling transition structure.

2. The parallel dual-sphere resonant cavity passive pulse compressor as described in claim 1, characterized in that, The length difference between the two standard circular waveguides is 5 / 8λ g Integer multiples of λ g Indicates the operating wavelength.

3. A parallel dual-sphere resonant cavity passive pulse compressor as described in claim 2, characterized in that, The standard circular waveguide is positioned at a distance of 1 / 4λ from the interface between the standard rectangular waveguide and the overmode waveguide. g At integer multiples of .

4. A parallel dual-sphere resonant cavity passive pulse compressor as described in claim 2 or 3, characterized in that, The T-junction has a chamfer in the middle to optimize the isolation between the input and output ends; the H-planes of the two standard rectangular waveguides have identical matching structures to optimize the reflection coefficient.

5. A parallel dual-sphere resonant cavity passive pulse compressor as described in claim 4, characterized in that, The matching structure is located at a distance of 1 / 4λ from the connection surface between the standard rectangular waveguide and the overmode waveguide. g At integer multiples of .

6. A parallel dual-sphere resonant cavity passive pulse compressor as described in claim 2 or 3, characterized in that, The width of the overmode waveguide is between λ and λ. g ~1.5λ g between.

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