Variable polarization adjustable attenuator with high power capacity

Abstract

The invention discloses a variable polarization adjustable attenuator with high power capacity, and belongs to the technical field of high-power microwave devices. The adjustable attenuator comprises a circular waveguide polarization pre-attenuator, a circular waveguide polarization main attenuator and a polarization filter which are arranged in sequence, and the circular waveguide polarization pre-attenuator, the circular waveguide polarization main attenuator and the polarization filter are rotatably connected through movable waveguide flanges. And attenuation adjustment and variable polarization adjustment of high-power microwaves are realized. According to the invention, any adjustable attenuation output from 0 to-18dB under the power capacity of 500MW can be realized, and the output of a TE11 mode in any polarization direction within the attenuation range from-3dB to-18dB has the advantages of simple adjustment, large degree of freedom and high power capacity.

Description

Technical Field

[0001] This invention belongs to the field of high-power microwave device technology, specifically relating to an adjustable attenuator based on a circular waveguide polarization attenuator and a radial four-way waveguide polarization filter. Background Technology

[0002] With the development of technologies such as pulsed power, plasma physics, and relativistic vacuum electronics, high-power microwave technology has rapidly advanced and gradually matured in application. As research into high-power microwave technology deepens, researchers' demands for studying high-power microwave effects have reached a new level. However, existing microwave sources suffer from limitations such as restricted output power range and fixed output polarization direction, failing to meet the needs of effect experiments where the test source power or polarization can be adjusted according to site or application requirements. Therefore, researching attenuators for high-power microwave effect experiments is of great value.

[0003] An attenuator is a microwave device that absorbs or dissipates the energy of an input microwave signal into free space, thereby attenuating the output power. Attenuators used in microwave systems generally fall into two categories: absorption attenuators and cutoff attenuators. Absorption attenuators primarily work by inserting a dielectric attenuating substrate into a waveguide, creating a surface current on the substrate. The surface resistance of the attenuator generates Joule heating, converting the electromagnetic energy into heat and dissipating it, thus attenuating the electromagnetic energy. Cutoff attenuators, on the other hand, utilize the principle of cutoff waveguides. By using a specific waveguide structure or adjusting the waveguide dimensions, the guided electromagnetic wave is kept in a cutoff state, causing the amplitude of the electromagnetic wave to decrease exponentially with the transmission distance.

[0004] In high-power microwave systems, due to the high power of the microwave source, conventional cutoff attenuators require limiting waveguide dimensions to achieve attenuation, which cannot meet power capacity requirements. Furthermore, they necessitate additional design of a front-end coupler to guide the microwave energy from the cutoff reflection into the absorption port, resulting in an overly complex overall structure. Existing cutoff microwave attenuators can achieve a power capacity of 2.5MW and adjustable attenuation from 0 to -18dB at a center frequency of 3GHz in the S-band. By changing the position of the internal dielectric reflector, the phase of the reflected wave can be adjusted, thus determining the absorption amplitude of the electromagnetic wave. However, this dielectric reflector placement method inevitably leads to the technical problem of dielectric surface breakdown under high power conditions, failing to meet the application requirements of high-power microwave platforms. Existing absorbing adjustable attenuators mainly employ direct insertion of an attenuator into a circular waveguide, achieving adjustable attenuation by controlling the rotation angle of the attenuator. However, this approach is also prone to heat dissipation and dielectric attenuator surface breakdown problems in high-power microwave systems. Therefore, research on attenuators with novel structures is of great significance.

[0005] In high-power microwave effect experiments, it is necessary to study the effects of beams with different polarization directions on target objects, thus requiring a system with variable polarization. Existing high-power variable polarizers mainly suffer from problems such as large size and easy introduction of clutter modes. If designed separately from the attenuator, they can easily lead to an excessively large overall system size, making them inconvenient to use. Therefore, it is quite necessary to design the attenuator module in conjunction with the variable polarization requirement. Summary of the Invention

[0006] To address the problems of existing high-power microwave attenuators, this invention provides a high-power capacity, variable-polarization adjustable attenuator. This invention consists of a circular waveguide polarization attenuator and a polarization filter at its rear end that controls the polarization direction. By rotating the circular waveguide polarization pre-attenuator, the circular waveguide polarization main attenuator, and the polarization filter, it can achieve an adjustable attenuation output of 0 to -18dB at a power capacity of 500MW, and an attenuation direction TE of any polarization direction within the attenuation range of -3dB to -18dB. 11 The output mode. This invention uses two identical circular waveguide polarized attenuators combined to achieve pre-attenuation and main attenuation of power respectively, which has the advantages of simple adjustment, high degree of freedom, and high power capacity.

[0007] The technical solution adopted in this invention is as follows: A high-power capacity variable polarization adjustable attenuator includes: a circular waveguide polarization pre-attenuator, a circular waveguide polarization main attenuator, and a polarization filter arranged sequentially. The three components are rotatably connected by a live waveguide flange. By rotating the circular waveguide polarization pre-attenuator, the circular waveguide polarization main attenuator, and the polarization filter, the attenuation and polarization of high-power microwaves can be adjusted.

[0008] The circular waveguide polarization pre-attenuator and the circular waveguide polarization main attenuator have the same structure, both including: a circular waveguide body, two T-shaped cavities symmetrically arranged on the outside of the circular waveguide body, and attenuation material; The circular waveguide body is used to transmit the input microwaves to the next stage structure; The T-shaped cavity consists of a horizontal part and a vertical part, both of which are parallel to the microwave transmission direction. The bottom end of the vertical part is connected to the circular waveguide body. The attenuating material is located inside the T-shaped cavity and is used to absorb microwave energy.

[0009] The polarization filter includes: an input circular waveguide, a radial four-way power divider waveguide, a rectangular-to-circular conversion waveguide, and an output circular waveguide arranged sequentially. The input circular waveguide is used to input the microwave transmitted by the circular waveguide polarization main attenuator to the radial four-way power divider waveguide. The radial four-way waveguide is a cross-shaped cavity structure composed of four rectangular waveguides; wherein, two symmetrically placed rectangular waveguides contain attenuation material, and the other two rectangular waveguides are set as bent waveguides so that the two output ports are close to each other and perpendicular to the axial direction of the output circular waveguide, and are connected to the rectangular-circular conversion waveguide. The rectangular-to-circular conversion waveguide has a rectangular waveguide port at one end and a circular waveguide port at the other end, which is connected to the output circular waveguide. The output circular waveguide is used to transmit the attenuated microwaves to subsequent devices.

[0010] Furthermore, the attenuation material in the T-shaped cavity is located in the longitudinal part and is formed by carving two identical isosceles triangular prism grooves in a rectangular column; each end of the two isosceles triangular prism grooves is provided with a triangular pyramid with the same structure, so that the bottom end of the groove transitions to the top end of the groove with a slope, thereby achieving impedance matching.

[0011] Furthermore, the transverse portion of the T-shaped cavity is filled with attenuating material to support and fix the attenuating material in the longitudinal portion.

[0012] Furthermore, the main body of the circular waveguide is a standard circular waveguide with a length of [missing information]. The length of the T-shaped cavity along the main body of the circular waveguide is... , > ; Furthermore, the longitudinal portion of the T-shaped cavity has a rectangular cross-section perpendicular to the axial direction of the circular waveguide body, with its long side being... The width is , The value range is 17.5mm~20mm; the bottom width of the isosceles triangular prism groove is , The value is ~ .

[0013] Furthermore, the height of the triangular pyramid parallel to the axis of the circular waveguide body is... , The value range is 10mm~15mm.

[0014] Furthermore, a stepped matching frustum is provided at the center of the radial four-way waveguide to achieve impedance matching from the input circular waveguide to the four rectangular waveguides.

[0015] Furthermore, the attenuation material inside the rectangular waveguide consists of two wedge-shaped blocks of the same shape, placed symmetrically; the two right-angled bases of the wedge-shaped blocks are respectively attached to the narrow side and the closed end of the rectangular waveguide.

[0016] Furthermore, the input circular waveguide and the output circular waveguide have the same structure, both using standard circular waveguides.

[0017] Furthermore, the length of the rectangular port width of the rectangular-circular conversion waveguide is... The length of the narrow side is The radius of the circular waveguide port is , length is ; The value range is 75mm~80mm. It is 72.14mm. It is 41.81mm. It is 40mm~50mm.

[0018] The beneficial effects of this invention are: This invention employs a novel three-section polarization rotating attenuator unit. By combining a circular waveguide pre-polarization attenuator with the main polarization attenuator of identical structure, both attenuation of the input microwave energy and deflection of the polarization direction can be achieved. By controlling the polarization attenuator, microwave output with a fixed polarization direction can be achieved, while energy from other orthogonal directions can be absorbed. The three sections working together can achieve arbitrary linear polarization TE within a wide bandwidth of 2.7GHz to 3.1GHz under attenuation conditions of -3dB to -18dB. 11 Rotational transmission performance.

[0019] This invention relates to a circular waveguide polarization pre-attenuator and a circular waveguide polarization main attenuator. By loading symmetrical T-shaped cavities on both sides of the circular waveguide and incorporating a novel attenuation material with a sawtooth shape within the T-shaped cavities, the TE (transient current) can be effectively improved. 11 The pattern generates wall currents on both sides of the sawtooth, making energy coupling and absorption easier. This structure allows for a wide adjustable attenuation range, high precision, and large power capacity, enabling microwave transmission with a power output of 500MW.

[0020] Compared to traditional attenuators, this invention employs a circular waveguide structure and utilizes the dominant mode TE of the circular waveguide. 11 The mode features a polarization direction, and an axisymmetric coupling absorption structure was designed; the TE with a fixed polarization direction... 11 After mode input, TE changes with different rotation angles of the circular waveguide polarization attenuator. 11 The amount of wave coupling into the absorption structure also changes accordingly, thus enabling adjustable power attenuation. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the adjustable attenuator according to an embodiment of the present invention.

[0022] Figure 2 This is a schematic diagram of the overall structure of the circular waveguide polarization attenuator according to an embodiment of the present invention.

[0023] Figure 3This is a schematic diagram of the overall structure of the polarization filter according to an embodiment of the present invention.

[0024] Figure 4 This is a schematic diagram of the structural dimensions of a circular waveguide polarized attenuator according to an embodiment of the present invention.

[0025] Figure 5 This is a schematic diagram of the dimensions of the triangular pyramid in the circular waveguide polarization attenuator of this invention.

[0026] Figure 6 The present invention provides a structural dimension diagram of a polarization filter.

[0027] Figure 7 In this embodiment of the invention, the angle of the fixed circular waveguide polarized main attenuator is... Transmission characteristic curves as the circular waveguide polarization pre-attenuator rotates.

[0028] Figure 8 In this embodiment of the invention, the angle of the fixed circular waveguide polarized main attenuator is... Transmission characteristic curves as the circular waveguide polarization pre-attenuator rotates.

[0029] Figure 9 This is the transmission characteristic curve of the device with frequency when the attenuation is at its maximum according to an embodiment of the present invention.

[0030] Figure 10 This is the transmission characteristic curve of the device as the rotation angle of the first two circular waveguide polarization attenuators is maximized when the output polarization direction torsion angle is at its maximum according to an embodiment of the present invention.

[0031] Figure 11 This is a diagram showing the electric field intensity distribution inside the device when the attenuation is minimized in an embodiment of the present invention.

[0032] Figure 12 This is a diagram showing the electric field intensity distribution inside the device when the attenuation is at its maximum according to an embodiment of the present invention.

[0033] Explanation of reference numerals in the attached figures: 1. Circular waveguide polarization pre-attenuator; 2. Circular waveguide polarization main attenuator; 3. Polarization filter; 11. Circular waveguide body; 12. Longitudinal portion of T-cavity; 13. Lateral portion of T-cavity; 14. Attenuation material of T-cavity; 141. Rectangular block; 142. Triangular prism slot; 143. Triangular pyramid; 31. Input circular waveguide; 32. Radial four-way waveguide; 33. Rectangular-circular conversion waveguide; 34. Output circular waveguide; 321. Matching frustum; 322. Wedge-shaped attenuation material. Detailed Implementation

[0034] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0035] This embodiment provides a high-power arbitrary linear polarization TE 11Directional adjustable attenuator, such as Figures 1-3 As shown, it includes a circular waveguide polarization pre-attenuator, a circular waveguide polarization main attenuator, and a polarization filter arranged in sequence; the three are rotatably connected by a live waveguide flange. By rotating the circular waveguide polarization pre-attenuator, the circular waveguide polarization main attenuator, and the polarization filter, the attenuation and polarization of high-power microwaves in the 2.7GHz~3.1GHz frequency band can be adjusted.

[0036] The circular waveguide polarization pre-attenuator and the circular waveguide polarization main attenuator have the same structure, both including: a circular waveguide body, two T-shaped cavities symmetrically arranged on the outside of the circular waveguide body, and attenuation material.

[0037] The circular waveguide body is used to transmit the input microwaves to the next stage structure.

[0038] The T-shaped cavity consists of a horizontal part and a vertical part, both of which are parallel to the microwave transmission direction. The bottom end of the vertical part is connected to the circular waveguide body.

[0039] The attenuation material is located inside the T-shaped cavity and is used to absorb microwave energy. The transverse part of the T-shaped cavity is filled with attenuation material to support and fix the longitudinal attenuation material. The attenuation material in the longitudinal part of the T-shaped cavity is composed of two identical isosceles triangular prism slots carved into a rectangular column. At each end of the two isosceles triangular prism slots, a triangular pyramid with the same structure is provided, so that the bottom end of the slot transitions to the top end of the slot with a slope, thereby achieving impedance matching.

[0040] The polarization filter includes: an input circular waveguide, a radial four-way power divider waveguide, a rectangular-to-circular conversion waveguide, and an output circular waveguide arranged sequentially.

[0041] The input circular waveguide is used to input the microwave transmitted by the circular waveguide polarization main attenuator to the radial four-way power divider waveguide.

[0042] The radial four-way waveguide is a cross-shaped cavity structure composed of four rectangular waveguides. Two symmetrically placed rectangular waveguides contain attenuation material, which consists of two identical symmetrically placed wedge-shaped blocks. The two right-angled bases of the wedge-shaped blocks are respectively attached to the narrow side and closed end of the rectangular waveguide. The other two rectangular waveguides are configured as bent waveguides, so that the two output ports are close to each other and perpendicular to the axial direction of the output circular waveguide, and are connected to the rectangular-to-circular conversion waveguide. A stepped matching frustum is also provided at the center of the radial four-way waveguide, with rounded edges, to achieve impedance matching from the input circular waveguide to the four rectangular waveguides.

[0043] The rectangular-to-circular conversion waveguide has a rectangular waveguide port at one end and a circular waveguide port at the other end, which is connected to the output circular waveguide.

[0044] The output circular waveguide is used to transmit the attenuated microwaves to subsequent devices.

[0045] like Figure 4 , 5 As shown, the structural dimensions of the circular waveguide polarization attenuator in this embodiment are as follows: , , , , , , , , .

[0046] like Figure 6 As shown in (a) and 6(b), the structural dimensions of the radial four-way power divider waveguide polarization filter in this embodiment are as follows: , , , , , , , , , , , , , , , , , .

[0047] The working principle of the adjustable attenuator of this invention is as follows: linear polarization TE 11 A wave is incident at port 1. When the circular waveguide prepolarization attenuator is rotated clockwise by an angle... At that time, assuming TE 11 When the wave polarization direction is consistent with the T-cavity direction, the theoretical absorption of the single-section circular waveguide polarization attenuator is minimized, and it is basically not affected by the T-cavity polarization direction. 11 The polarization direction of the wave is affected; the rotation angle of the main polarization attenuator of the circular waveguide is also affected. The situation is the same as described above; in this case, the polarization direction of TE does not change. 11 The wave enters the polarization filter, and all energy enters the 2-port via the symmetrical bent waveguide. With... , As the angle increases (range 0~60°), TE 11 The wall current generated by the wave at the T-cavity gradually increases, thus gradually increasing the attenuation. Simultaneously, the axisymmetric structure affects the TE... 11 Linearly polarized waves produce a torsional effect, causing TE 11 The polarization direction of the wave line is deflected; when the deflected TE 11After a wave enters the polarization filter, the deflected TE wave can be filtered by the principle of wave superposition. 11 The wave is orthogonally decomposed into two polarization directions, one of which has a TE. 11 After the wave enters the symmetrical curved waveguide, it is output from port 2, and the TE in the other polarization direction... 11 The wave energy is absorbed by the attenuating ceramic within the symmetrical rectangular waveguide, thus achieving a TE with a fixed polarization direction. 11 Mode output. If other polarization directions are required during application, TE... 11 For waves, the polarization filter can be twisted to a specific angle.

[0048] like Figure 7 The figure shows the port transmission characteristic curve of this embodiment, corresponding to a fixed rotation angle of the circular waveguide main polarization attenuator. Rotation angle of the circular waveguide prepolarized attenuator The figure shows the overall transmission characteristic curve of the attenuator. It indicates that when the circular waveguide polarized attenuator is fixed at its minimum attenuation value, the overall attenuation loss is -0.74 dB, and as the circular waveguide pre-polarized attenuator gradually rotates, it reaches... The maximum decay occurs at that time.

[0049] like Figure 8 The figure shows the port transmission characteristic curve of this embodiment, corresponding to a fixed rotation angle of the circular waveguide main polarization attenuator. Time The figure shows the overall transmission characteristic curve of the attenuator. This figure illustrates fixing the circular waveguide main polarization attenuator as... When rotated to At this time, the maximum attenuation of the entire attenuator can be obtained as -18.54dB.

[0050] like Figure 9 The figure shows the port transmission characteristic curve of this embodiment, corresponding to... , The graph shows the overall transmission performance of the attenuator in the operating frequency band. It indicates that the overall reflection of the device is relatively small when the attenuator attenuation is at its maximum, at an operating frequency of 2.9 GHz. 11 <-30dB, and the reflection coefficient is less than -15dB in the 2.7GHz~3.1GHz range; Mode 2 in the figure is the input TE 11 The orthogonal mode of the mode, as shown in the figure, means that input mode 1 will not excite reflection or transmission of mode 2, thus ensuring the purity of the device's input and output modes.

[0051] like Figure 10 The figure shows the device's rotation angle with the first two stages of circular waveguide polarization attenuators when the output polarization direction twist angle is at its maximum (±90°) in the embodiment. , The figure shows the transmission characteristic curve. It indicates that when the required output polarization direction at port 2 deviates most from the initial input polarization direction at port 1, the device can achieve a minimum power attenuation of approximately -3dB for polarization-twisted output by adjusting the angles of the first two stages of circular waveguide polarization attenuators. This demonstrates that the model can achieve arbitrary angle polarization TE within the attenuation range of -3dB to -18dB. 11 The output of the pattern.

[0052] like Figure 11 As shown , The electric field distribution inside the time attenuator. This figure shows the electric field intensity distribution when a 500MW TE is input at port 1. 11 When the attenuation is at its lowest, the electric field strength transmitted in the cavity of the attenuator is basically less than 70MV / m, which is lower than the vacuum breakdown field strength, indicating that the model can withstand 500MW of power transmission.

[0053] like Figure 12 As shown , The electric field distribution inside the time attenuator. This figure shows the electric field intensity distribution when a 500MW TE is input at port 1. 11 When the attenuation is at its highest, the highest field strength inside the attenuator cavity is about 27MV / m, which is much lower than the vacuum breakdown field strength of 70MV / m, indicating that the power capacity of the model is above 500MW and has good power capacity.

Claims

1. A high-power capacity, variable-polarization, adjustable attenuator, characterized in that, include: The circular waveguide polarization pre-attenuator, circular waveguide polarization main attenuator, and polarization filter are arranged in sequence and are rotatably connected by a live waveguide flange. By rotating the circular waveguide polarization pre-attenuator, circular waveguide polarization main attenuator, and polarization filter, the attenuation and polarization of high-power microwaves can be adjusted. The circular waveguide polarization pre-attenuator and the circular waveguide polarization main attenuator have the same structure, both including: a circular waveguide body, two T-shaped cavities symmetrically arranged on the outside of the circular waveguide body, and attenuation material; The circular waveguide body is used to transmit the input microwaves to the next stage structure; The T-shaped cavity consists of a horizontal part and a vertical part, both of which are parallel to the microwave transmission direction. The bottom end of the vertical part is connected to the circular waveguide body. The attenuating material is located inside the T-shaped cavity and is used to absorb microwave energy; The polarization filter includes: an input circular waveguide, a radial four-way power divider waveguide, a rectangular-to-circular conversion waveguide, and an output circular waveguide arranged sequentially. The input circular waveguide is used to input the microwave transmitted by the circular waveguide polarization main attenuator to the radial four-way power divider waveguide. The radial four-way waveguide is a cross-shaped cavity structure composed of four rectangular waveguides; wherein, the two symmetrically placed rectangular waveguides are filled with attenuation material, and the other two rectangular waveguides are set as bent waveguides, so that the two output ports are close to each other and connected to the rectangular-circular conversion waveguide. The rectangular-to-circular conversion waveguide has a rectangular waveguide port at one end and a circular waveguide port at the other end, which is connected to the output circular waveguide. The output circular waveguide is used to transmit the attenuated microwaves to subsequent devices.

2. The high-power capacity variable polarization adjustable attenuator as described in claim 1, characterized in that, The attenuation material inside the T-shaped cavity is located in the longitudinal part and is formed by two identical isosceles triangular prism slots carved out of a rectangular column. At each end of the two isosceles triangular prism slots, a triangular pyramid with the same structure is provided, so that the bottom end of the slot transitions to the top end of the slot with a slope, thereby achieving impedance matching.

3. The high-power capacity variable polarization adjustable attenuator as described in claim 2, characterized in that, The transverse portion of the T-shaped cavity is filled with attenuating material to support and fix the attenuating material in the longitudinal portion.

4. The high-power capacity variable polarization adjustable attenuator as described in claim 3, characterized in that, The main body of the circular waveguide is a standard circular waveguide with a length of [missing information]. ; The length of the T-shaped cavity along the main body of the circular waveguide is... , > .

5. The high-power capacity variable polarization adjustable attenuator as described in claim 4, characterized in that, The longitudinal portion of the T-shaped cavity has a rectangular cross-section perpendicular to the axis of the circular waveguide body, with its longer side being... The width is , The value range is 17.5mm~20mm; the bottom width of the isosceles triangular prism groove is , The value is ~ .

6. The high-power capacity variable polarization adjustable attenuator as described in claim 5, characterized in that, The height of the triangular pyramid parallel to the axis of the circular waveguide body , The value range is 10mm~15mm.

7. A high-power capacity variable polarization adjustable attenuator as described in any one of claims 2-6, characterized in that, A stepped matching frustum is provided at the center of the radial four-way waveguide to achieve impedance matching from the input circular waveguide to the four rectangular waveguides.

8. The high-power capacity variable polarization adjustable attenuator as described in claim 7, characterized in that, The attenuation material inside the rectangular waveguide consists of two identical, symmetrically placed wedge-shaped blocks; the two right-angled bases of the wedge-shaped blocks are respectively attached to the narrow side and the closed end of the rectangular waveguide.

9. A high-power capacity variable polarization adjustable attenuator as described in claim 8, characterized in that, The input circular waveguide and the output circular waveguide have the same structure, both using standard circular waveguides.

10. A high-power capacity variable polarization adjustable attenuator as described in claim 9, characterized in that, The rectangular port width of the circular conversion waveguide is [length missing]. The length of the narrow side is The radius of the circular waveguide port is , length is ; The value range is 75mm~80mm. It is 72.14mm. It is 41.81mm. It is 40mm~50mm.

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