High Power Microwave Circularly Polarized Radial Line Slot Array Antenna

Abstract

The present invention discloses a high-power microwave circularly polarized radial line slot array antenna, the purpose of which is to solve the problems of low compactness and insufficient power capacity of high-power microwave antennas. The present invention is composed of a coaxial waveguide, a radial line leaky waveguide, a flange, and an antenna cover. The coaxial waveguide, the radial line leaky waveguide, the flange, and the antenna cover are coaxially connected in order from input to output; one end of the coaxial waveguide is connected to a microwave source, and the other end is connected to the center of the radial line leaky waveguide; the output end of the radial line leaky waveguide is welded to the lower surface of the flange, and the upper surface of the flange is connected to the antenna cover. The radial line leaky waveguide is composed of a radial line bottom plate, a radial line middle plate, a short-circuit cylinder, a slot array mouth surface, and a waveguide wall. A plurality of slots are opened on the slot array mouth surface to radiate microwaves. Each circle of slots is distributed with metal walls on both sides of the radial direction, and the surface of the radial line middle plate has a reflection-offsetting metal ridge. The present invention has a compact structure, good circular polarization performance, and high power capacity and gain.

Description

Technical Field

[0001] The present invention relates to a radiation antenna in the technical field of high-power microwaves, in particular to a high-power microwave antenna operating in a high frequency band (300 MHz to 300 GHz). Background Art

[0002] High-power microwave (HPM) generally refers to strong electromagnetic radiation with a frequency of 300MHz to 300GHz, a peak power greater than 100MW or an average power greater than 1MW. The applications of high-power microwaves are diverse, mainly including: high-power pulse radar, used for accurate target resolution under wide frequency band; high-energy particle radio frequency accelerator, used in high-energy physics and nuclear physics research; controlled thermonuclear plasma heating based on the electron cyclotron resonance mechanism and high-power microwave weapons.

[0003] As the terminal of the entire high-power microwave system, the high-power microwave antenna radiates the energy generated by the microwave source into the free space in a specific form. Its performance directly determines whether the energy generated by the microwave source can be effectively radiated outward and accurately act on the target. With the development of high-power microwave applications towards practicality, new and higher requirements are put forward for the polarization mode of high-power microwave antennas. Circularly polarized antennas are increasingly attracting the attention of researchers due to their strong anti-interference ability and stable performance. However, in the field of high-power microwaves, the antenna structure that currently realizes circularly polarized radiation is relatively simple, and there are generally problems such as low circular polarization purity and complex antenna structure. These problems seriously limit the application of circularly polarized antennas in high-power microwave antennas.

[0004] So far, the research results of high-power microwave sources are mainly concentrated in the L, S, C, X bands (all with frequencies below 12 GHz), and the development of higher-frequency high-power microwave equipment will be one of the next focuses in the field of high-power microwave research. Combined with the trend of high-frequency development of high-power microwave systems, it is increasingly urgent to develop high-frequency compact high-power microwave radiation antennas such as Ku band (frequency range of 12 to 18 GHz).

[0005] Since the existing Ku-band radiating antennas have large losses and insufficient power capacity, and the circularly polarized antennas in the high-power microwave field have complex structures and low circular polarization purity, which cannot meet the application requirements of high-power microwaves, how to design a new circularly polarized feed antenna with a simple structure, compact axial direction and high power capacity is a technical issue that technicians in this field are very concerned about. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a new type of high-power microwave circularly polarized radial line slot array antenna, which has a compact structure, coaxial input and output, good circular polarization performance, and high power capacity and gain. It solves the problems of current high-power microwave antennas that are not compact, have insufficient power capacity, and are difficult to apply in high-frequency bands, and meets the requirements for the development of high-power microwave devices towards miniaturization and compactness.

[0007] The technical solution adopted by the present invention to solve its technical problem is:

[0008] The present invention consists of four parts: a coaxial waveguide, a radial line leaky waveguide, a flange, and an antenna cover. It is defined that the end of the coaxial waveguide, radial line leaky waveguide, flange, and antenna cover close to the microwave source is the input end, and the end away from the microwave source is the output end; the coaxial waveguide, radial line leaky waveguide, flange, and antenna cover are coaxially connected in order from input to output; one end of the coaxial waveguide is connected to the microwave source as the input port of the high-power microwave circularly polarized radial line slot array antenna, and the other end is connected to the center of the radial line leaky waveguide; the center of the input end of the radial line leaky waveguide is connected to the coaxial waveguide, and the output end of the radial line leaky waveguide is welded to the lower surface of the flange; the lower surface of the flange is welded to the output end of the radial line leaky waveguide, and the upper surface of the flange is connected and fixed to the antenna cover by screws.

[0009] The coaxial waveguide consists of an outer conductor and an inner conductor, both of which are made of metal materials. The input ends of the outer and inner conductors of the coaxial waveguide are connected to the microwave source; the inner conductor is a solid cylinder with a diameter of D1 and a height of H1+H2+H3; the outer conductor is a hollow cylinder with an inner diameter of D2 and a height of H1+H2, and the wall thickness of the outer conductor is S; the inner conductor is coaxially nested inside the outer conductor, and the output end of the inner conductor is connected to the radial line mid-plate, and a 45° angle is chamfered at the connection, and the chamfer radius is R2.

[0010] Coaxial waveguide receives TE from high power microwave source 11 Mode microwave, for TE 11 Mode microwave transmission makes TE 11 The mode microwave is fed into a radial line leaky waveguide, in which the annular channel between the inner and outer conductors of the coaxial waveguide is used to transmit TE 11 Mode microwave, the outer conductor of the coaxial waveguide is used to shield external electromagnetic interference and protect the TE transmitted in the coaxial waveguide. 11 Mode microwaves are not affected by external electromagnetic waves.

[0011] The radial line leaky waveguide is composed of a radial line bottom plate, a radial line middle plate, a short-circuit cylinder, a slot array surface, and a waveguide wall, all of which are made of metal materials. The radial line bottom plate is annular, the radial line middle plate and the slot array surface are disc-shaped, and are arranged in parallel from input to output. The radial line bottom plate, the slot array surface and the waveguide wall together form a cylindrical cavity. The radial line bottom plate is a metal ring with a through hole in the center. The thickness of the radial line bottom plate is H2, the outer diameter of the radial line bottom plate is D6, the diameter of the central through hole of the radial line bottom plate is equal to D2, and is the same as the inner diameter of the outer conductor of the coaxial waveguide. The central through hole of the radial line bottom plate is connected to the output end of the outer conductor, the lower end of the central through hole of the radial line bottom plate is welded to the output end of the outer conductor of the coaxial waveguide, and the inner edge of the welding place between the central through hole of the radial line bottom plate and the outer conductor of the coaxial waveguide is chamfered at 45°, and the chamfer radius is R1; the radial line middle plate is located at the center of the cylindrical cavity, the diameter of the radial line middle plate is D3, the thickness is H4, the edge of the radial line middle plate is chamfered at 45°, the chamfer radius is R3, and the diameter is The distance from the surface of the radial line midplane close to the input end to the surface of the radial line bottom plate close to the output end is H3, and the distance from the surface of the radial line midplane close to the output end to the surface of the slot array mouth close to the input end is H5; the short-circuit cylinder is a metal cylinder, the diameter of the short-circuit cylinder is D7, and the height is equal to H5; the waveguide wall is a metal ring, the outer diameter of the waveguide wall is equal to D6, the inner diameter is D4, and the height is H7; a plurality of slots are opened on the slot array mouth surface to radiate microwaves, the diameter of the slot array mouth surface is D6, and the thickness of the slot array mouth surface is equal to the slot depth H6 thereon, and a 45° angle is chamfered on the inner side of the connection between the radial line bottom plate and the waveguide wall and the inner side of the connection between the slot array mouth surface and the waveguide wall, and the chamfer radius is R4. The central through hole of the radial line bottom plate is welded with the output end of the coaxial waveguide outer conductor, the surface of the radial line bottom plate close to the output end is connected to the surface of the waveguide wall close to the input end, and the surface of the waveguide wall close to the output end is connected to the surface of the slot array mouth surface close to the input end; at the center of the radial line middle plate and the slot array mouth surface, a short-circuit cylinder is used to connect the two in a direction perpendicular to the disk surfaces of the two, and the center of the radial line middle plate is set as point O, and the center of the slot array mouth surface is set as point O', and the two points are connected to form a central axis OO'; the input end of the short-circuit cylinder is connected to the surface of the radial line middle plate close to the output end, and the output end of the short-circuit cylinder is connected to the surface of the slot array mouth surface close to the input end; the surface of the slot array mouth surface close to the input end is connected to the surface of the waveguide wall close to the output end, and a flange is welded on the surface of the slot array mouth surface close to the output end; the short-circuit cylinder, the radial line middle plate and the slot array mouth surface are coaxial.

[0012] Microwaves in radial leaky waveguide cavities will generate standing wave fields during transmission. 11In the process of transmitting toward the center axis OO', the mode microwave radiates part of the electromagnetic energy to the output end through the gap coupling, avoiding the breakdown phenomenon caused by excessive concentration of the standing wave field at the center axis OO', thereby effectively improving the overall power capacity of the antenna. The radial line bottom plate is equivalent to the continuation of the outer conductor of the coaxial waveguide, shielding external electromagnetic interference; the radial line middle plate is equivalent to the continuation of the inner conductor of the coaxial waveguide, which is the TE transmitting radially away from the center axis OO'. 11 The mode microwave is folded and converted to obtain the TE propagating radially toward the central axis OO'. 11 Mode microwave; the short-circuited cylinder transmits TE along the radial direction close to the central axis OO' 11 The mode microwave is reflected back and transmitted along the radial direction close to the central axis OO' 11 mode microwave and TE propagating radially away from the central axis OO' 11 The mode microwaves are coherently superimposed to form a standing wave field in the radial line leaky waveguide cavity. The slot array surface is used to 11 The waveguide wall, radial line bottom plate, and slot array aperture form a closed cylindrical cavity, which radiates TE 11 The microwave mode is confined in a cylindrical cavity to prevent TE 11 The mode microwave is lost during the transmission process, and at the same time, mechanical support is provided to the slot array aperture surface to maintain the structural stability of the radial line leaky waveguide.

[0013] The flange is annular and made of metal material, with an outer diameter equal to D6, an inner diameter of D5 and a height of H8. The lower surface of the flange is welded to the slot array surface, and the upper surface is fixedly connected to the radome by screws; the radome is disc-shaped and made of polytetrafluoroethylene, with a diameter of D6 and a thickness of H9, and the radome is fixedly connected to the flange by screws. The flange provides sufficient mechanical support for the radome and withstands vibration and impact from the external environment. The radome protects the high-power microwave circularly polarized radial line slot array antenna from damage by the external environment, increases the reliability of the high-power microwave circularly polarized radial line slot array antenna, and improves the long-term stability and service life of the high-power microwave circularly polarized radial line slot array antenna.

[0014] There are N circles of slots on the surface of the slot array aperture near the output end (i.e., the upper surface) for radiating microwaves. There are N circles of slots in total, where N is a positive integer. The value range of N is generally 5≤N≤13. The innermost circle of slots is the first circle, and the distance from the center of the innermost circle of slots to the center O' of the slot array aperture is ρ1. The distance from the center of the nth circle of slots to the center O' of the slot array aperture is ρ n Each circle of gaps is composed of several capsule-shaped gap units, which are arranged uniformly, equally spaced, and parallel along the circumferential direction. The circumferential spacing between the centers of adjacent capsule-shaped gap units is S. Φ, radial spacing is S ρ , and ρ n =ρ n-1 +S ρ The capsule-shaped gap unit is at an angle of θ to the radial direction, θ = 45°, and the length of the capsule-shaped gap unit in the nth circle of gaps is L n The width of the capsule-shaped gap unit is represented by W n It means that the depth of the capsule-shaped gap unit is equal to the thickness H6 of the gap array surface. From the first gap to the nth gap, the length L of the capsule-shaped gap unit in each gap is n Different, the length L of the capsule-shaped gap unit n As n increases, the gap length close to the central axis OO' is smaller, while the gap length away from the central axis OO' is longer, so as to ensure that the equivalent impedance of each circle of gaps is equal. The width W of the capsule-shaped gap unit in each circle of gaps is n The same, 2≤n≤N. The N circles of slots on the slot array surface are used to radiate TE to the output end. 11 mode microwave, in which the capsule-type slot unit is at an angle of 45° to the radial direction. The capsule-type slot unit inclined at 45° effectively cuts the wall current on the slot array mouth surface in the radial direction. When combined in the circumferential direction, the capsule-type slot units can be closely arranged to improve the wall current cutting efficiency.

[0015] On the surface of the slot array mouth surface close to the output end, each circle of slots is distributed with metal walls on both sides of the radial direction. The number of metal walls is one more than the number of slots, and there are N+1 metal walls in total. The metal wall is circular in the top view of the slot array mouth surface, and rectangular in the cross-sectional view along the BB' plane. The width of the metal wall is w1 and the height is h1. The innermost circle of metal walls is the first circle, and the distance from the center of the innermost circle of metal walls to the center O' of the slot array mouth surface is q1, and the distance from the center of the mth circle of metal walls to the center O' of the slot array mouth surface 24 is q m , the radial distance between the center of the m-1th metal wall and the center of the mth metal wall is equal to S ρ , and there is q m =q m-1 +S ρ , 2≤m≤N+1. Two adjacent metal walls are equivalent to a parallel plate waveguide, and N+1 metal walls are equivalent to N parallel plate waveguides. The slots inclined at a 45° angle effectively cut the wall current on the slot array surface, generating a displacement current perpendicular to the slot in the slot. According to electromagnetic theory, the changing displacement current generates a radiation electric field, which is at an angle of 45° to the radial direction. The radiation electric field can be decomposed into equal amplitude and same phase x-direction electric fields E x and the electric field E in the y direction y The electric field E in the x direction x and the electric field E in the y directiony After propagating through the metal wall, a 90° phase difference is generated, and the x-direction electric field E with a 90° phase difference x and the electric field E in the y direction y The synthesized circularly polarized wave is radiated into the free space, thereby realizing the radiation output of converting the linearly polarized wave into the circularly polarized wave.

[0016] On the surface of the radial line mid-plate close to the output end, a reflection-cancelling metal ridge is loaded. The number of turns of the reflection-cancelling metal ridge is the same as the number of turns of the gap, and the number of turns of the reflection-cancelling metal ridge is equal to N turns. The reflection-cancelling metal ridge is in a circular shape in the top view of the radial line mid-plate, and in a rectangular shape in the front cross-sectional view along the BB' plane. The width of the reflection-cancelling metal ridge is w2, and the height is h2. The surface edge of the reflection-cancelling metal ridge close to the output end is rounded, and the chamfer radius is R5. The innermost circle of the reflection-cancelling metal ridge is the first circle, and the center of the innermost circle of the reflection-cancelling metal ridge is aligned with the center of the first circle of gaps, the center of the nth circle of the reflection-cancelling metal ridge is aligned with the center of the nth circle of gaps, the distance between the center of the innermost circle of the reflection-cancelling metal ridge and the center O of the radial line mid-plate is equal to ρ1, and the distance from the center of the nth circle of the reflection-cancelling metal ridge to the center O of the radial line mid-plate is equal to ρ n , the radial distance between the center of the n-1th reflection-cancelling metal ridge and the center of the nth reflection-cancelling metal ridge is equal to S ρ , which is the same as the radial spacing between the centers of adjacent capsule-shaped gap units, and ρ n =ρ n-1 +S ρ , 2≤n≤N. The reflection-cancelling metal ridge is used to cancel the reflected waves excited by the capsule-type slot unit on each circle of slots on the slot array mouth surface. If the reflection-cancelling metal ridge is not added, the reflected waves excited by each circle of slots on the slot array mouth surface are in the same phase state and will be superimposed on each other, resulting in a large electromagnetic reflection to the input end of the present invention.

[0017] For the convenience of description, the conditions satisfied by the structural parameters of the above designs are introduced here:

[0018] 1. The parameters D1 and D2 of the coaxial waveguide must meet the propagation conditions of the TE11 mode in the coaxial waveguide, that is, λ0 is the wavelength of input microwave in free space, Where c is the speed of light in vacuum and f is the input TE 11 The frequency of the mode microwave, and D2>D1>0, H1>H3>H2>0.

[0019] 2. The 45° chamfer radius at the connection between the outer conductor of the coaxial waveguide and the central through hole of the radial line bottom plate is R1, and the 45° chamfer radius at the connection between the inner conductor of the coaxial waveguide and the radial line middle plate is R2, satisfying R1>0, R2>0.

[0020] 3. The outer diameter of the waveguide wall of the radial-line leaky waveguide (equal to the outer diameter D6 of the radial-line bottom plate of the radial-line leaky waveguide), the inner diameter D4 of the waveguide wall, the inner-wall chamfer radius R4, the height H7, and the diameter D3, thickness H4, and edge chamfer radius R3 of the radial-line middle plate satisfy D6 > D4 > D3 > 0 and R4 > R3 > 0. To suppress the generation of higher-order modes in the radial-line leaky waveguide, the distance H5 between the surface of the radial-line middle plate near the output end and the surface of the slot array aperture near the input end needs to be less than half of the waveguide wavelength. Since the wave propagating in the radial-line leaky waveguide is TE 11 wave, its waveguide wavelength λ g is also equal to the free-space wavelength λ0, that is, 0 < H5 < 0.5λ0. Usually, H3 = H5 > 0, H4 > 0, H7 = H3 + H4 + H5, and the specific values of D6, D4, D3, R4, R3, H3, H4, and H5 are optimized and designed by the electromagnetic simulation software CST Studio Suit.

[0021] 4. The radial spacing S between the centers of the capsule-shaped slot elements on the slot array aperture ρ should satisfy the operating conditions of the standing-wave antenna, that is, S ρ = λ0. To ensure the maximum improvement of the aperture efficiency of the present invention, the circumferential spacing S Φ between the centers of adjacent capsule-shaped slot elements = λ0 / 3, and the angle θ between the capsule-shaped slot element and the radial direction is a constant of 45°. The distance ρ1 from the center of the innermost slot to the center O' of the slot array aperture is determined according to actual needs, but this value should neither be too small nor too large. If it is too small, the innermost slot will be too narrow, resulting in field breakdown and low power capacity. If it is too large, the utilization rate of the antenna aperture will be reduced, causing a decrease in aperture efficiency. Generally, 0.5λ0 < ρ1 < 1.5λ0.

[0022] 5. The length L of the nth turn of the capsule-shaped slot elements n is determined by the electric-field distribution on the slot array aperture. When the electric-field distribution on the slot array aperture satisfies uniform distribution, the normalized equivalent resistance r n of the nth turn of the slot should satisfy where ρ n is the distance from the center of the nth turn of the slot to the center O' of the slot array aperture, and ρ n = ρ n-1 + S ρ , 2 ≤ n ≤ N, where N represents the total number of turns of the slots, and the value range of N is generally 5 ≤ N ≤ 13. The width W n of the capsule-shaped slot element and the mathematical relationship with the equivalent resistance r n can be obtained through simulation by the electromagnetic simulation software CST Studio Suit (after the shape of the capsule-shaped slot element is determined, the width W n of the capsule-shaped slot element and the equivalent resistance rn There must be a unique corresponding mathematical relationship). After determining ρ1 and the total number of slits N, the distance ρ from the center of the nth slit to the center of the slit array surface O' is n It is also uniquely determined, so the normalized equivalent resistance r of the nth gap is n It can be calculated, and then the width W of the gap in the nth circle can be obtained n From the first circle of gaps to the nth circle of gaps, the length of the capsule-shaped gap unit in each circle of gaps is different. The length of the capsule-shaped gap unit L n As n increases, L1<L2<…<L n <…<L N , the gap length close to the central axis OO' is smaller, while the gap length away from the central axis OO' is longer, so as to ensure that the equivalent impedance of each circle of gaps is equal, and the width of the capsule-shaped gap unit in each circle of gaps is the same, W1 = W2 = ... = W n =…=W N The depth of the capsule-shaped slit unit is equal to the thickness of the slit array surface H6,0 <H6<0.5λ0。

[0023] 6. On the surface of the slot array near the output end, each circle of slots has metal walls on both sides of the radial direction, and the height of the metal wall is h1,0 m , the radial distance between the center of the m-1th metal wall and the center of the mth metal wall is equal to S ρ , and there is q m =q m-1 +S ρ , 2≤m≤N+1. The number of metal wall turns is one more than the number of gap turns, and the metal wall has a total of N+1 turns. Since the first circle of metal wall is distributed on the side of the first circle of gap close to the central axis OO', 0<q1<ρ1. After determining q1 and the total number of metal wall turns N+1, the distance from the center of the mth circle of metal wall to the center O' of the gap array mouth is q m The only certainty.

[0024] ​7. On the surface of the radial line mid-plate near the output end, a reflection-cancelling metal ridge is loaded. The height of the reflection-cancelling metal ridge is h2 and the width is w2. <h2<H5,w2> 0, the edge of the surface of the reflection-cancelling metal ridge close to the output end is rounded, and the chamfer radius is R5, R5>0; the innermost reflection-cancelling metal ridge is the first circle, the center of the innermost reflection-cancelling metal ridge is aligned with the center of the first circle gap, the center of the nth reflection-cancelling metal ridge is aligned with the center of the nth circle gap, the distance from the center of the innermost reflection-cancelling metal ridge to the center O of the radial midplane is equal to ρ1, and the distance from the center of the nth reflection-cancelling metal ridge to the center O of the radial midplane is equal to ρ n , the radial distance between the center of the n-1th reflection-cancelling metal ridge and the center of the nth reflection-cancelling metal ridge is equal to S ρ , which is the same as the radial spacing between the centers of adjacent capsule-shaped gap units, and ρ n =ρ n-1 +S ρ The number of turns of the reflection-cancelling metal ridge is the same as the number of turns of the gap, and the number of turns of the reflection-cancelling metal ridge is equal to N turns, 2≤n≤N. The specific values ​​of h2, w2 and R5 need to be optimized and designed by the electromagnetic simulation software CST Studio Suit.

[0025] 8. The diameter D7 of the short-circuit cylinder should satisfy the standing wave field superposition condition, that is, D7=2ρ1-λ0, and 0<D7<2λ0.

[0026] 9. The inner diameter D5 and height H8 of the flange are determined according to actual needs, and D6>D5>0, H8>2λ0. The thickness H9 of the antenna cover should be an integer multiple of λ / 2, where λ is the waveguide wavelength of the microwave when passing through the antenna cover, and get where ε r is the relative dielectric constant of the radome dielectric material. When the radome is made of polytetrafluoroethylene, ε r =2.55, K is a positive integer.

[0027] Through the electromagnetic simulation software CST Studio Suit, under the conditions of D6>D5>D4>D3>D2>D1>0, D7=2ρ1-λ0, 0<D7<2λ0, R1>0, R2>0, R4>R3>0, R5>0, H1>0, H2>0, H3=H5>0, H4>0, H7=H3+H4+H5,H8>0, w1=λ0-d,0<w1<λ0, w2>0, 0 n <…<L N ​, W1=W2=…=W n =…=W N , under the condition of S>0, setting the antenna radiation efficiency greater than 99%, we can obtain parameters D1, D2, D3, D4, D5, D6, D7, R1, R2, R3, R4, R5, H1, H2, H3, H4, H5, H6, H7, H8, H9, w1, w2, h1, h2, W n , L n , ρ1, q1. S is usually 2 to 5 mm.

[0028] The working process of the present invention is:

[0029] Coaxial waveguide receives TE from high power microwave source 11 Mode microwave, coaxial waveguide to TE 11 Mode microwave transmission makes TE 11 The mode microwave is fed into the radial line leaky waveguide from the center O of the radial line midplane, forming a TE transmission in the radial direction away from the central axis OO' 11 Mode microwave, TE transmission of radial line midplane in the radial direction away from the central axis OO' 11 The mode microwave is folded and converted to obtain the TE propagation along the radial direction close to the central axis OO' 11 mode microwave, the short-circuited cylinder transmits the TE in the radial direction close to the central axis OO' 11 The mode microwave is reflected back and transmitted along the radial direction close to the central axis OO' 11 mode microwave and TE propagating radially away from the central axis OO' 11 The coherent superposition of the TE mode microwaves forms a standing wave in the radial line leaky waveguide cavity. 11 When the mode microwave propagates in the radial line leaky waveguide, the radial line middle plate is equivalent to the continuation of the inner conductor of the coaxial waveguide, and the radial line bottom plate is equivalent to the continuation of the outer conductor of the coaxial waveguide.

[0030] The geometric centers of the capsule-shaped slot units distributed on the slot array mouth surface are arranged uniformly, equally spaced, and parallel along the circumference, at an angle of 45° to the radial direction. The capsule-shaped slot units inclined at an angle of 45° effectively cut the wall current on the slot array mouth surface in the radial direction, and then generate a displacement current perpendicular to the capsule-shaped slot unit in the middle of the capsule-shaped slot unit. The close arrangement of the capsule-shaped slot units in the circumferential direction can improve the wall current cutting efficiency. According to electromagnetic theory, the changing displacement current generates a radiation electric field, which is -45° to the radial direction. The radiation electric field can be decomposed into an equal amplitude and same phase x-direction electric field E x and the electric field E in the y direction y Each circle of gaps has metal walls on both sides of the radial direction. The two adjacent circles of metal walls are equivalent to a parallel plate waveguide. The electric field E in the x direction is xand the electric field E in the y direction y After propagating through the metal wall, a 90° phase difference is generated, and the x-direction electric field E with a 90° phase difference x and the electric field E in the y direction y After synthesis, it is equivalent to the circularly polarized wave radiating into the free space, thereby realizing the radiation output of the linearly polarized wave converted into a circularly polarized wave.

[0031] In order to suppress the generation of high-order modes in the radial line leaky waveguide, the spacing between the surface of the radial line mid-plate near the output end and the surface of the slot array mouth near the input end is less than half the waveguide wavelength. A reflection-cancelling metal ridge is loaded on the surface of the radial line mid-plate near the output end, which can cancel the in-phase superimposed reflected waves excited by the capsule-shaped slot unit on each circle of slots on the slot array mouth. If the reflection-cancelling metal ridge is not added, the reflected waves excited by each circle of slots on the slot array mouth are in the same phase state and will be superimposed on each other, resulting in a large reflection to the input end of the present invention.

[0032] Compared with the prior art, the present invention can achieve the following technical effects:

[0033] 1. The present invention adopts a radial line leaky waveguide so that microwaves radiate part of the electromagnetic energy through gap coupling during the inward propagation of the radial line leaky waveguide cavity, thereby avoiding excessive concentration of the electric field at the central axis OO', thereby effectively improving the overall power capacity of the present invention.

[0034] 2. In the present invention, the capsule-shaped slot units on the slot array mouth surface are at an angle of 45° to the radial direction. The capsule-shaped slot units inclined at an angle of 45° effectively cut the wall current on the slot array mouth surface in the radial direction. The capsule-shaped slot units are arranged uniformly, equally spaced, and in parallel in the circumferential direction to improve the wall current cutting efficiency.

[0035] 3. The spacing between the surface of the radial line mid-plate close to the output end and the surface of the slot array aperture close to the input end of the present invention is less than half the waveguide wavelength, which effectively suppresses the generation of high-order modes in the radial line waveguide.

[0036] 4. The present invention loads a reflection-cancelling metal ridge on the surface of the radial line mid-plate near the output end to cancel the in-phase superimposed reflected waves excited by the capsule-type slot units on each circle of slots on the slot array aperture surface, so that the overall reflection of the present invention will not be very large.

[0037] 5. The combination of the capsule-type slot unit structure of the present invention with the metal wall and the reflection-cancelling metal ridge enables the present invention to have a higher power capacity and gain, and can be applied to high-power microwave radiation antennas in high-frequency bands.

[0038] 6. The present invention has the characteristics of compact structure, high gain, good circular polarization performance and high power capacity, which meets the requirements of the development of high-power microwave devices towards miniaturization and compactness. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a schematic diagram of the overall structure of the high-power microwave circularly polarized radial line slot array antenna of the present invention.

[0040] Figure 2 yes Figure 1 Isometric section view along the AA' plane.

[0041] Figure 3 yes Figure 1 Front section view along the AA' plane.

[0042] Figure 4 yes Figure 2 A top view and a partially enlarged view of the middle slot array surface 24.

[0043] Figure 5 yes Figure 2 A top view and a partially enlarged view of the radial line waveguide midplate 22.

[0044] Figure 6 yes Figure 4 Sectional view along plane BB' and partial enlarged view.

[0045] Figure 7 It is a two-dimensional directional diagram of embodiment 1 of the present invention.

[0046] Figure 8 It is a two-dimensional directional diagram of embodiment 2 of the present invention. DETAILED DESCRIPTION

[0047] The specific implementation of the present invention is further described below in conjunction with the drawings and examples.

[0048] Figure 1 Schematic diagram of the overall structure of the high-power microwave circularly polarized radial line slot array antenna of the present invention; Figure 1 As shown, the present invention is composed of a coaxial waveguide 1, a radial line leaky waveguide 2, a flange 3, and an antenna cover 4. The coaxial waveguide 1, the radial line leaky waveguide 2, the flange 3, and the antenna cover 4 are defined as the input end at one end close to the microwave source, and the output end at the other end far from the microwave source. The coaxial waveguide 1, the radial line leaky waveguide 2, the flange 3, and the antenna cover 4 are coaxially connected in the order from input to output, as shown in FIG. Figure 1As shown, the input end is at the bottom, the output end is at the top, and the coaxial waveguide 1, the radial line leaky waveguide 2, the flange 3, and the antenna cover 4 are coaxially connected from bottom to top. One end of the coaxial waveguide 1 is connected to the microwave source as the input port of the high-power microwave circularly polarized radial line slot array antenna, and the other end is connected to the center of the radial line leaky waveguide 2; the center of the input end of the radial line leaky waveguide 2 is connected to the coaxial waveguide 1, and the output end of the radial line leaky waveguide 2 is welded to the lower surface of the flange 3; the lower surface of the flange 3 is welded to the output end of the radial line leaky waveguide 2, and the upper surface of the flange 3 is connected and fixed to the antenna cover 4 by screws.

[0049] Coaxial waveguide 1 receives TE from a high power microwave source 11 Mode microwave, TE 11 Mode microwave transmission makes TE 11 The mode microwave is fed into the radial line leaky waveguide 2. The microwave in the radial line leaky waveguide 2 cavity will generate a standing wave field during the transmission process, TE 11 The mode microwave radiates part of the electromagnetic energy to the output end through slot coupling during transmission near the central axis OO', avoiding the breakdown phenomenon caused by excessive concentration of the standing wave field at the central axis OO', thereby effectively improving the overall power capacity of the antenna. The flange 3 provides sufficient mechanical support for the antenna cover 4 and withstands the vibration and impact of the external environment, which is conducive to the TE transmission in the radial line leaky waveguide 2. 11 The high-power microwave circularly polarized radial line slot array antenna provides shielding protection to prevent external interference signals from entering the high-power microwave circularly polarized radial line slot array antenna, thereby ensuring the stability of the high-power microwave circularly polarized radial line slot array antenna. The radome 4 protects the high-power microwave circularly polarized radial line slot array antenna from damage by the external environment, reduces the influence of factors such as temperature changes and mechanical vibrations caused by changes in the external environment on the antenna performance, increases the reliability of the high-power microwave circularly polarized radial line slot array antenna, and improves the long-term stability and service life of the high-power microwave circularly polarized radial line slot array antenna.

[0050] Figure 2 yes Figure 1 Isometric section view along the AA' plane. Figure 3 yes Figure 1 Front section view along AA' plane. Figure 2 , Figure 3As shown, the coaxial waveguide 1 is composed of an outer conductor 11 and an inner conductor 12, both of which are made of metal materials. The input end of the coaxial waveguide 1 (i.e., the input end of the outer conductor 11 and the inner conductor 12) is connected to the microwave source. The outer conductor 11 is a cylinder, whose inner diameter is D2, height is H1+H2, and the cylinder wall thickness of the outer conductor 11 is S; the inner conductor 12 is coaxially nested inside the outer conductor 11, and the output end of the inner conductor 12 is connected to the radial line middle plate 22, and a 45° angle is chamfered at the connection, and the chamfer radius is R2; the output end of the outer conductor 11 is connected to the bottom of the radial line leaky waveguide 2 (i.e., the center of the radial line bottom plate 21); the annular channel between the inner conductor 12 and the outer conductor 11 of the coaxial waveguide is used to transmit TE 11 mode microwave, the outer conductor 11 is used to shield external electromagnetic interference and protect the TE transmitted in the inner conductor 12 11 Mode microwaves are not affected by external electromagnetic waves.

[0051] like Figure 2 , Figure 3As shown, the radial line leaky waveguide 2 is composed of a radial line bottom plate 21, a radial line middle plate 22, a short-circuit cylinder 23, a slot array surface 24, and a waveguide wall 25, all of which are made of metal materials. The radial line bottom plate 21 is annular, the radial line middle plate 22 and the slot array surface 24 are disc-shaped, the radial line bottom plate 21, the radial line middle plate 22, and the slot array surface 24 are arranged in parallel in the order from input to output, the surface of the radial line bottom plate 21 close to the output end, the surface of the slot array surface 24 close to the input end and the waveguide wall 25 together form a cylindrical cavity, and the radial line middle plate 22 is located at the center of the cylindrical cavity (the radial line bottom plate 21 and the slot array surface 24 are parallel in the horizontal direction, and the radial line middle plate 22 is at the same vertical distance from the radial line bottom plate 21 and the slot array surface 24). At the center O' of the radial line mid-plate 22 and the slot array opening 24, a short-circuit cylinder 23 is used to connect the radial line mid-plate 22 and the slot array opening 24 in a direction perpendicular to the disk surface of the radial line mid-plate 22 and the slot array opening 24. The inner conductor 12 is a solid cylinder with a diameter of D1 and a height of H1+H2+H3, where H1 is the distance between the surface of the coaxial waveguide 1 near the input end and the surface of the radial line bottom plate 21 near the input end, H2 is the thickness of the radial line bottom plate 21, and H3 is the distance between the surface of the radial line bottom plate 21 near the output end and the surface of the radial line mid-plate 22 near the input end; the output end of the outer conductor 11 is connected to the center of the radial line bottom plate 21. The radial line bottom plate 21 is a metal ring, the outer diameter of the radial line bottom plate 21 is D6, the inner diameter of the radial line bottom plate 21 is equal to the inner diameter D2 of the coaxial waveguide outer conductor 11, the central through hole of the radial line bottom plate 21 is connected to the output end of the outer conductor 11, the lower end of the central through hole of the radial line bottom plate 21 is welded to the output end of the outer conductor 11, and the inner edge of the central through hole and the outer conductor 11 is chamfered at 45°, and the chamfer radius is R1. The waveguide wall 25 is a metal ring, the outer diameter of the waveguide wall 25 is D6, the inner diameter is D4, and the height is H7; the surface of the radial line bottom plate 21 near the output end is connected to the surface of the waveguide wall 25 near the input end, and the surface of the waveguide wall 25 near the output end is connected to the surface of the slot array aperture 24 near the input end. A plurality of capsule-shaped slot units are provided on the slot array aperture 24 to radiate microwaves. The slot array aperture 24 has a diameter of D6 and a thickness of H6. Its surface near the input end is connected to the surface near the output end of the waveguide wall 25, and a flange 3 is welded on the output end surface. A 45° angle is chamfered at the inner side of the connection between the radial line bottom plate 21 and the waveguide wall 25 and at the inner side of the connection between the slot array aperture 24 and the waveguide wall 25, and the chamfer radius is R4. The radial line middle plate 22 has a diameter of D3 and a thickness of H4; the edge of the radial line middle plate 22 is chamfered at a 45° angle, and the chamfer radius is R3. The distance from the surface near the input end of the radial line middle plate 22 to the surface near the output end of the radial line bottom plate 21 is equal to H3, and the distance from the surface near the output end of the radial line middle plate 22 to the surface near the input end of the slot array aperture 24 is equal to H6.The input end of the short-circuit cylinder 23 is connected to the surface of the radial line mid-plate 22 near the output end, and the output end of the short-circuit cylinder 23 is connected to the surface of the slot array mouth surface 24 near the input end. The short-circuit cylinder 23, the radial line mid-plate 22 and the slot array mouth surface 24 are coaxial. The diameter of the short-circuit cylinder 23 is D7, and the height is equal to H6. The radial line bottom plate 21 is equivalent to the continuation of the coaxial waveguide outer conductor 11, shielding external electromagnetic interference; the radial line mid-plate 22 is equivalent to the continuation of the coaxial waveguide inner conductor 12, and transmits TE in the radial direction away from the central axis OO'. 11 The mode microwave is folded and converted to obtain the TE propagating radially toward the central axis OO'. 11 Mode microwave; short-circuit cylinder 23 will be transmitted in the radial direction close to the central axis OO 'TE 11 The mode microwave is reflected back and transmitted along the radial direction close to the central axis OO' 11 mode microwave and TE propagating radially away from the central axis OO' 11 The mode microwaves are coherently superimposed to form a standing wave field in the radial line leaky waveguide 2 cavity. The slot array aperture 24 is used to 11 The waveguide wall 25, the radial line bottom plate 21, and the slot array aperture 24 form a closed cylindrical cavity, which radiates the TE 11 The microwave mode is confined in a cylindrical cavity to prevent TE 11 The mode microwaves are lost during the transmission process, and at the same time provide mechanical support to the slot array aperture 24 to maintain the structural stability of the radial line leaky waveguide 2.

[0052] like Figure 1 and Figure 3 As shown, the flange 3 is annular and made of metal material, with an outer diameter equal to D6, an inner diameter of D5, and a height of H8. The lower surface of the flange 3 is welded to the surface (i.e., the upper surface) of the slot array opening 24 close to the output end, and the upper surface is fixedly connected to the lower surface of the antenna cover 4 by screws. The flange 3 provides sufficient mechanical support for the antenna cover 4 and withstands the vibration and impact of the external environment to ensure the stability of the high-power microwave circularly polarized radial line slot array antenna.

[0053] The radome 4 is disc-shaped, with a diameter equal to D6 and a thickness of H9. It is made of polytetrafluoroethylene with a relative dielectric constant of 2.55. The lower surface of the radome 4 is fixedly connected to the upper surface of the flange 3 by screws. The radome 4 is used to protect the high-power microwave circularly polarized radial line slot array antenna from damage by the external environment, reduce the influence of factors such as temperature changes and mechanical vibrations caused by changes in the external environment on the antenna performance, increase the reliability of the high-power microwave circularly polarized radial line slot array antenna, and improve the long-term stability and service life of the high-power microwave circularly polarized radial line slot array antenna.

[0054] Figure 4 is a top view of the slot array surface 24 of the present invention, Figure 4 (a) is a top view of the slot array surface 24 of the present invention, Figure 4 (b) Yes Figure 4 (a) Enlarged view at I, Figure 4 (c) Yes Figure 4 (b) Enlarged view of II. Figure 4 As shown, the surface (i.e., the upper surface) of the slot array aperture surface 24 close to the output end has N circles of slots, such as Figure 4 As shown in (a), there are N circles of gaps, in this figure N = 13, the innermost circle of gaps is the first circle, the distance from the center of the innermost circle of gaps to the center of the gap array surface O' is ρ1, and the distance from the center of the nth circle of gaps to the center of the gap array surface O' is ρ n Each circle of gaps is composed of several capsule-shaped gap units, which are arranged evenly, equally spaced and parallel along the circumferential direction. Figure 4 As shown in (b), the circumferential spacing between the centers of adjacent capsule-shaped gap units is S Φ , radial spacing is S ρ , and ρ n =ρ n-1 +S ρ , the capsule-shaped gap unit is at an angle θ to the radial direction, θ = 45°; Figure 4 As shown in (c), the length of the capsule-shaped gap unit in the nth gap is L n The width of the capsule-shaped gap unit in the nth gap is represented by W n It means that the depth of the capsule-shaped slit unit is equal to the thickness H6 of the slit array surface 24. From the first slit to the nth slit, the length of the capsule-shaped slit unit in each slit is different. The length L of the capsule-shaped slit unit is n As n increases, L1<L2<…<L n <…<L N , the gap length close to the central axis OO' is smaller, while the gap length away from the central axis OO' is longer, so as to ensure that the equivalent impedance of each circle of gaps is equal, and the width of the capsule-shaped gap unit in each circle of gaps is the same, W1 = W2 = ... = W n =…=W N , 2≤n≤N. The N circles of slots on the slot array aperture 24 are used to radiate TE to the output end. 11 mode microwave, wherein the capsule-type slot unit is at an angle of 45° to the radial direction, and the capsule-type slot unit inclined at an angle of 45° effectively cuts the wall current on the slot array mouth surface 24 in the radial direction, and the close arrangement of the capsule-type slot units in the circumferential direction can improve the wall current cutting efficiency.

[0055] Figure 5It is a top view and a partial enlarged view of the radial line middle plate 22 of the present invention. Figure 5 (a) is a top view of the radial line mid-plate 22 of the present invention, Figure 5 (b) Yes Figure 5 (a) Enlarged view of III. Figure 5 As shown in (a), the radial line mid-plate 22 is disc-shaped. On the surface of the radial line mid-plate 22 close to the output end, N circles of reflection-cancelling metal ridges are loaded. Figure 5 (a) is a circular, reflection-cancelling metal ridge in the front cross-sectional view along the BB' plane. Figure 6 (a)) is rectangular, the width of the reflection cancellation metal ridge is w2, the height is h2, and the edge of the surface of the reflection cancellation metal ridge near the output end is rounded, and the chamfer radius is R5 (see Figure 6 (a)); Figure 6 yes Figure 4 Front view and partial enlarged view along BB' plane. Figure 6 (b) Yes Figure 4 Sectional view along plane BB', Figure 6 (a) Yes Figure 6 (b) Enlarged view of IV. Figure 6 As shown in (b), the reflection canceling metal ridges are numbered 221, 222, 223, 224, 225, 226, 227, 228, 229, 2210, 2211, 2212, and 2213. Figure 5 As shown in (a), the innermost reflection-cancelling metal ridge is the first circle, the distance between the center of the innermost reflection-cancelling metal ridge 221 and the center O of the radial midplane 22 is equal to ρ1, and the distance between the center of the nth reflection-cancelling metal ridge 22n and the center O of the radial midplane 22 is equal to ρ n ;like Figure 5 As shown in (b), the center of the nth circle of reflection-cancelling metal ridge is aligned with the center of the nth circle of gaps, and the radial spacing between the center of the n-1th circle of reflection-cancelling metal ridge and the center of the nth circle of reflection-cancelling metal ridge is equal to S ρ , which is the same as the radial spacing between the centers of adjacent capsule slot units. The reflection-cancelling metal ridge is used to cancel the reflected waves excited by the capsule slot units on each circle of slots on the slot array aperture 24. If the reflection-cancelling metal ridge is not added, the reflected waves excited by each circle of slots on the slot array aperture 24 are in the same phase state and will be superimposed on each other, resulting in a large electromagnetic reflection on the input end of the present invention.

[0056] like Figure 4 As shown in (a), on the surface of the slot array aperture 24 close to the output end, metal walls are distributed on both sides of each circle of slots, and the metal walls are in a circular shape in the top view of the slot array aperture 24; Figure 6As shown in (a), the metal wall is rectangular in the cross-sectional view along the BB' plane, and the width of the metal wall is w1 and the height is h1; Figure 6 As shown in (b), the metal walls are numbered 241, 242, 243, 244, 245, 246, 247, 248, 249, 2410, 2411, 2412, 2413, and 2414. Figure 4 As shown in (a), the innermost metal wall 241 is the first circle, the distance between the center of the innermost metal wall 241 and the center O' of the slot array mouth surface 24 is q1, and the distance between the center of the mth metal wall 24m and the center O' of the slot array mouth surface 24 is q m , the radial distance between the center of the m-1th metal wall and the center of the mth metal wall is equal to S ρ , the number of metal wall turns is one more than the number of slot turns, the metal wall has N+1 turns in total, and 2≤m≤N+1. Two adjacent turns of metal wall are equivalent to a parallel plate waveguide, and N+1 turns of metal wall are equivalent to N parallel plate waveguides. The slots inclined at an angle of 45° effectively cut the wall current on the slot array aperture 24, generating a displacement current perpendicular to the slot in the slot. According to electromagnetic theory, the changing displacement current generates a radiation electric field, which is -45° to the radial direction. The radiation electric field can be decomposed into equal amplitude and same phase x-direction electric fields E x and the electric field E in the y direction y The electric field E in the x direction x and the electric field E in the y direction y After propagating through the metal wall, a 90° phase difference is generated, and the x-direction electric field E with a 90° phase difference x and the electric field E in the y direction y After synthesis, it is equivalent to the circularly polarized wave radiating into the free space, thereby realizing the radiation output of the linearly polarized wave converted into a circularly polarized wave.

[0057] In order to clearly indicate the central axis OO', Figure 1 , Figure 2 , Figure 3 , Figure 6 The O is not marked at the center of the radial line in the plate 22, and O' is not marked at the center of the slot array mouth surface (24) (because the lines are crossed when marked at the center), and Figure 4 O' is clearly marked in Figure 5 O is clearly marked in the figure. Taking OO' as the central axis is just for the convenience of description and to clearly illustrate that O and O' are located on the central axis.

[0058] Example 1

[0059] The specific design dimensions of Example 1 of a high-power microwave circularly polarized radial line slot array antenna for 10 GHz (i.e., the frequency of the input microwave source is 10 GHz, corresponding to a microwave wavelength of 30 mm) are given below when N=7:

[0060] At this frequency, the diameter D1 of the inner conductor 11 of the coaxial waveguide 1 is 32 mm, the inner diameter D2 of the outer conductor 12 is 56 mm, the length of the inner conductor 11 is H1+H2+H3=37.83 mm, and the length of the outer conductor 12 is H1+H2=55+5=60 mm; the outer diameter D6 of the waveguide wall 25 of the radial line leaky waveguide 2 is 460 mm, the chamfer radius R1 of the connection between the outer conductor 11 and the radial line bottom plate 21 is 6.26 mm, and the chamfer radius R2 of the connection between the inner conductor 12 and the radial line middle plate 22 is 8.78 mm; the inner diameter D4 of the waveguide wall 25 of the radial line leaky waveguide 2 is 450 mm, and the inner side chamfer radius R4 is 8.8 mm. The diameter D3 of the radial line middle plate 22 is 426 mm, the thickness H4 is 10 mm, and the chamfer radius R3 of the edge of the radial line middle plate 22 is 2.2 mm. The distance H3 from the radial line middle plate 22 near the input end surface to the radial line bottom plate 21 near the output end surface is 12 mm, and the distance H5 from the radial line middle plate 22 near the output end surface to the slot array 24 near the input end surface is 12 mm. Select N = 7, the innermost circle of slots is the first circle, and the distance from the center of the first circle of slots to the center of the slot array 24 is ρ1 = 25 mm. The width W of the capsule-shaped slot unit n =4mm, the depth H6 of the optimized capsule-shaped gap unit is =2mm. The circumferential spacing S between the centers of adjacent capsule-shaped gap units Φ =10mm, radial spacing S ρ =30mm, the included angle between the capsule-shaped gap unit and the radial direction is θ=45°, and the size parameters corresponding to each circle of gaps are shown in Table 1.

[0061] Table 1 Design parameters of the gaps in each circle in Example 1

[0062]

[0063] Table 2 Radius of metal wall in each circle in Example 1

[0064]

[0065] The distance between the center of each circle of metal wall and the center of the slot array surface O' is shown in Table 2. The metal wall width w1 = 11.72 mm, the height h1 = 6.57 mm, and the radial spacing between the center of the mth circle of metal wall and the center of the m+1th circle of metal wall is S ρ=30mm; the width of the reflection-cancelling metal ridge w2 = 2mm, the height h2 = 2.4mm, the chamfer radius of the edge of the reflection-cancelling metal ridge R5 = 0.7mm, the center distance between two adjacent reflection-cancelling metal ridges S ρ =30mm.

[0066] The diameter of the short-circuit cylinder 23 is D7 = 20 mm, and the height is H5 = 12 mm. The distance from the upper surface of the radial line bottom plate 21 to the lower surface of the slot array opening 24 is H7 = 34 mm. The outer diameter of the flange 3 is D6 = 460 mm, the inner diameter is D5 = 450 mm, and the height is H8 = 70 mm. The antenna cover 4 is disc-shaped and made of polytetrafluoroethylene with a relative dielectric constant of ε r =2.55. The diameter D6 of the radome 4 is 460 mm, and the thickness K = 3. The wall thickness S of the outer conductor 12 of the coaxial waveguide 1 is 5 mm.

[0067] Example 1 The radiation performance of a high-power microwave circularly polarized radial line slot array antenna with a center frequency of 10 GHz is as follows: Figure 7 As shown, Figure 7 The two-dimensional radiation pattern of Example 1 of the present invention is given, where the horizontal axis is the pitch angle, which is the angle between the vector and the central axis OO' in the spherical coordinate system, and the vertical axis is the gain of the antenna. The dotted line represents the actual test result in the laboratory, and the solid line represents the simulation result obtained by the electromagnetic simulation software CST Studio Suit. Figure 7 It can be seen that at the center frequency of 10GHz, when using TE 11 During mode injection, due to the central symmetry of the antenna structure and the electromagnetic wave mode fed, the antenna gain is maximum at a pitch angle of 0°, regardless of simulation or test. The simulation results are consistent with the measured results, and the maximum antenna gain is 28.74dB. When the injection power is 0.5W, the maximum internal electric field is 1668V / m. According to the metal surface breakdown field strength of 50MV / m under vacuum conditions, the power capacity of the present invention when working at 10GHz is approximately 0.64GW.

[0068] Example 2

[0069] The specific design dimensions of Example 2 of a high-power microwave circularly polarized radial line slot array antenna for 14.25 GHz (i.e., the frequency of the input microwave source is 14.25 GHz, corresponding to a microwave wavelength of 21.04 mm) are given below, when N=13:

[0070] At this frequency, the diameter of the inner conductor 11 of the coaxial waveguide 1 is D1=84mm, the inner diameter of the outer conductor 12 is D2=100mm, the length of the inner conductor 11 is H1+H2+H3=27+4+8=39mm, and the length of the outer conductor 12 is H1+H2=27+4=31mm; the outer diameter of the waveguide wall 25 of the radial line leaky waveguide 2 is D6=600mm, the chamfer radius R1=2mm at the connection between the outer conductor 11 and the radial line bottom plate 21, and the chamfer radius R2=6.5mm at the connection between the inner conductor 12 and the radial line middle plate 22; the inner diameter of the waveguide wall 25 of the radial line leaky waveguide 2 is D4=570mm, and the inner side chamfer radius R4=6.17mm. The diameter of the radial line middle plate 22 is D3=554mm, the thickness H4=8mm, and the chamfer radius R3=1.8mm at the edge of the radial line middle plate 22. The distance H3 from the radial line middle plate 22 near the input end surface to the radial line bottom plate 21 near the output end surface is 8mm, and the distance H5 from the radial line middle plate 22 near the output end surface to the slot array 24 near the input end surface is 8mm. Select N = 13, the innermost circle of slots is the first circle, and the distance from the center of the first circle of slots to the antenna axis is ρ1 = 28.325mm. Capsule-type slot unit width W n =3.5mm, the depth of the optimized capsule gap unit H6 = 2mm. The circumferential spacing S between the centers of adjacent capsule gap units Φ =7.01mm, radial spacing S ρ =21.04mm, the included angle between the capsule-shaped gap unit and the radial direction is θ=45°, and the size parameters corresponding to each circle of gaps are shown in Table 3.

[0071] Table 3 Design parameters of the gaps in each circle in Example 2

[0072]

[0073]

[0074] Table 4 Radius of metal wall in each circle in Example 2

[0075]

[0076] The distances between each circle of metal wall and the center O' of the slot array are shown in Table 4. The metal wall width w1 = 6.73 mm, the height h1 = 5.98 mm, and the radial spacing between the center of the mth circle of metal wall and the center of the m+1th circle of metal wall is S ρ =20.1mm; the width of the reflection-cancelling metal ridge w2 = 1.426mm, the height h2 = 1.695mm, the chamfer radius of the reflection-cancelling metal ridge edge R5 = 0.5mm, the center distance between two adjacent reflection-cancelling metal ridges S ρ =20.1mm.

[0077] The diameter of the short-circuit cylinder 23 is D7 = 36 mm, and the length is H5 = 8 mm. The distance from the upper surface of the radial line bottom plate 21 to the lower surface of the slot array opening 24 is H7 = 24 mm. The outer diameter of the flange 3 is D6 = 600 mm, the inner diameter is D5 = 580 mm, and the height is H8 = 50 mm. The antenna cover 4 is disc-shaped and made of polytetrafluoroethylene with a relative dielectric constant of ε r =2.55. The diameter D6 of the radome 4 is 600 mm, and the thickness K = 2. The wall thickness S of the outer conductor 12 of the coaxial waveguide 1 is 2 mm.

[0078] The radiation performance of the high-power microwave circularly polarized radial line slot array antenna with a central frequency of 14.25 GHz in this embodiment is shown in Figure 8 As shown, Figure 8 The two-dimensional radiation pattern of Example 2 of the present invention is given, where the horizontal axis is the pitch angle, which is the angle between the vector and the central axis OO' in the spherical coordinate system, and the vertical axis is the gain of the antenna. The dotted line represents the actual test results in the laboratory, and the solid line represents the simulation results obtained by the electromagnetic simulation software CST Studio Suit. Figure 8 It can be seen that at the center frequency of 14.25GHz, when TE 11 During mode injection, due to the central symmetry of the antenna structure and the electromagnetic wave mode fed, the antenna gain is maximum at a pitch angle of 0°, regardless of simulation or test, and the simulation results are consistent with the test results, with a maximum antenna gain of 38.4dB. When the injection power is 0.5W, the maximum internal electric field is 1171V / m. According to the metal surface breakdown field strength of 50MV / m under vacuum conditions, the power capacity of the present invention when working at 14.25GHz is approximately 0.91GW.

[0079] By comparing Example 1 with Example 2, it can be concluded that the larger the number of slot turns N on the slot array mouth surface, the higher the gain of the present invention at the corresponding working frequency point, and the greater the power capacity. The present invention has strong flexibility, and the number of slot turns N can be flexibly adjusted according to actual application requirements. The present invention adopts a radial line leakage waveguide so that microwaves radiate a part of the electromagnetic energy through slot coupling during the inward propagation of the radial line leakage waveguide cavity, thereby avoiding excessive concentration of the electric field to the central axis OO', thereby effectively improving the overall power capacity of the antenna. At the same time, the combination of the capsule-type slot unit structure with the metal wall and the reflection-offsetting metal ridge makes the entire radiating antenna have a higher gain. The present invention has coaxial input and output, compact circumferential size structure, good circular polarization performance, high power capacity and gain, and solves the problems of low compactness, limited power capacity and difficulty in application in high frequency bands of current high-power microwave antennas.

[0080] The above implementation modes are only used to illustrate the present invention, but not to limit the present invention. Ordinary technicians in the relevant technical field can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions also fall within the protection scope of the present invention.

Claims

1. A high-power microwave circularly polarized radial line slot array antenna, characterized in that: The high-power microwave circularly polarized radial line slot array antenna is composed of a coaxial waveguide (1), a radial line leaky waveguide (2), a flange (3), and an antenna radome (4); it is defined that one end of the coaxial waveguide (1), the radial line leaky waveguide (2), the flange (3), and the antenna radome (4) close to the microwave source is the input end, and the end far from the microwave source is the output end; the coaxial waveguide (1), the radial line leaky waveguide (2), the flange (3), and the antenna radome (4) are coaxially connected in sequence from the input to the output, with the input end at the bottom and the output end at the top, and the coaxial waveguide (1), the radial line leaky waveguide (2), the flange (3), and the antenna radome (4) are coaxially connected from bottom to top; one end of the coaxial waveguide (1) is connected to the microwave source as the input port of the high-power microwave circularly polarized radial line slot array antenna, and the other end is connected to the center of the radial line leaky waveguide (2); the center of the input end of the radial line leaky waveguide (2) is connected to the coaxial waveguide (1), and the output end of the radial line leaky waveguide (2) is welded to the lower surface of the flange (3); the lower surface of the flange (3) is welded to the output end of the radial line leaky waveguide (2), and the upper surface of the flange (3) is fixedly connected to the antenna radome (4) by screws; The coaxial waveguide (1) is composed of an outer conductor (11) and an inner conductor (12), both of which are made of metal materials. The outer conductor (11) is a cylinder with an inner diameter of D2; the inner conductor (12) is a solid cylinder with a diameter of D1. The inner conductor (12) is coaxially nested inside the outer conductor (11); the output end of the inner conductor (12) is connected to a radial line middle plate (22) and is chamfered at 45° at the connection point, with a chamfer radius of R2; the output end of the outer conductor (11) is connected to the center of a radial line bottom plate (21) of a radial line leaky waveguide (2); the annular channel between the inner conductor (12) and the outer conductor (11) of the coaxial waveguide is used to transmit TE 11 mode microwave, making TE 11 The mode microwave is fed into the radial line leaky waveguide (2), and the outer conductor (11) is used to shield external electromagnetic interference; The radial line leaky waveguide (2) is composed of a radial line bottom plate (21), a radial line middle plate (22), a short-circuit cylinder (23), a slot array mouth surface (24), and a waveguide wall (25), all of which are made of metal materials; the radial line bottom plate (21) is in a circular ring shape, the radial line middle plate (22) and the slot array mouth surface (24) are in a disc shape, the radial line bottom plate (21), the radial line middle plate (22), and the slot array mouth surface (24) are arranged in parallel in the order from input to output, the surface of the radial line bottom plate (21) close to the output end, the surface of the slot array mouth surface (24) close to the input end and the waveguide wall (25) together form a cylindrical cavity, the radial line middle plate (22) is located at the center of the cylindrical cavity, and the radial line middle plate (22) is 1.5 meters away from the radial line bottom plate (21). and the vertical distance from the slot array mouth surface (24); at the center O' of the radial line middle plate (22) and the slot array mouth surface (24), a short-circuit cylinder (23) is used to connect the radial line middle plate (22) and the slot array mouth surface (24) in a direction perpendicular to the disk surface of the radial line middle plate (22) and the slot array mouth surface (24); the radial line bottom plate (21) is a metal ring, the outer diameter of the radial line bottom plate (21) is D6, the inner diameter of the radial line bottom plate (21) is equal to the inner diameter D2 of the coaxial waveguide outer conductor (11), the central through hole of the radial line bottom plate (21) is connected to the output end of the outer conductor (11), the lower end of the central through hole of the radial line bottom plate (21) is welded to the output end of the outer conductor (11), and the central through hole and the The inner edge of the welding position of the outer conductor (11) is chamfered at 45°, and the chamfer radius is R1; the waveguide wall (25) is a metal ring, the outer diameter of the waveguide wall (25) is equal to D6, the inner diameter is D4, and the height is H7; the surface of the radial line bottom plate (21) close to the output end is connected to the surface of the waveguide wall (25) close to the input end, and the surface of the waveguide wall (25) close to the output end is connected to the surface of the slot array mouth surface (24) close to the input end; a plurality of capsule-shaped slot units are opened on the slot array mouth surface (24) to radiate microwaves, the diameter of the slot array mouth surface (24) is equal to D6, the thickness is H6, the surface of the slot array mouth surface (24) close to the input end is connected to the surface of the waveguide wall (25) close to the output end, and a flange plate (3) is welded on the output end surface; the radial line bottom plate (21) and the waveguide wall (25) are connected to each other. The inner side of the connection of the guide wall (25) and the inner side of the connection of the slot array mouth surface (24) and the waveguide wall (25) are chamfered at 45°, and the chamfer radius is R4; the diameter of the radial line middle plate (22) is D3, and the thickness is H4; the edge of the radial line middle plate (22) is chamfered at 45°, and the chamfer radius is R3; the distance from the surface of the radial line middle plate (22) close to the input end to the surface of the radial line bottom plate (21) close to the output end is equal to H3, and the distance from the surface of the radial line middle plate (22) close to the output end to the surface of the slot array mouth surface (24) close to the input end is H5; the input end of the short-circuit cylinder (23) is connected to the surface of the radial line middle plate (22) close to the output end, and the output end of the short-circuit cylinder (23) is connected to the surface of the slot array mouth surface (24) close to the input end;The short-circuit cylinder (23), the radial line middle plate (22) and the slot array opening surface (24) are coaxial; the diameter of the short-circuit cylinder (23) is D7, and the height is equal to H6; the radial line bottom plate (21) shields external electromagnetic interference; the radial line middle plate (22) transmits TE in a radial direction away from the central axis OO'; 11 The mode microwave is folded and converted to obtain the TE propagating radially toward the central axis OO'. 11 Mode microwave; short-circuited cylinder (23) will be close to the central axis OO 'direction of the TE radial transmission 11 The mode microwave is reflected back and transmitted along the radial direction close to the central axis OO' 11 mode microwave and TE propagating radially away from the central axis OO' 11 The mode microwaves are coherently superimposed to form a standing wave field in the radial line leaky waveguide (2) cavity; the slot array aperture (24) is used to 11 The mode microwave radiates part of the electromagnetic energy to the output end through slot coupling; The closed cylindrical cavity formed by the waveguide wall (25), the radial line bottom plate (21) and the slot array aperture (24) forms a TE 11 The microwave mode is confined in a cylindrical cavity to prevent TE 11 The mode microwaves are lost during the transmission process, and at the same time, mechanical support is provided to the slot array aperture surface (24), thereby maintaining the structural stability of the radial line leaky waveguide (2); The surface of the slot array aperture (24) near the output end has N circles of slots, and there are N circles of slots in total, where N is a positive integer; the innermost circle of slots is the first circle, and the distance between the center of the innermost circle of slots and the center O' of the slot array aperture is ρ1, and the distance between the center of the nth circle of slots and the center O' of the slot array aperture is ρ n , 2≤n≤N; each circle of gaps is composed of a number of capsule-shaped gap units, which are arranged uniformly, equally spaced, and parallel along the circumferential direction. The circumferential spacing between the centers of adjacent capsule-shaped gap units is S Φ , radial spacing is S ρ , the capsule-shaped slot unit forms an angle θ with the radial direction; the N circles of slots on the slot array aperture surface (24) are used to radiate TE to the output end 11 Modular microwave; The radial line middle plate (22) is in the shape of a disk. The surface of the radial line middle plate (22) near the output end is loaded with N circles of reflection-cancelling metal ridges. The reflection-cancelling metal ridges are in the shape of a ring in the top view of the radial line middle plate and in the shape of a rectangle in the front view along the BB' plane. The width of the reflection-cancelling metal ridges is w2 and the height is h2. The surface edge of the reflection-cancelling metal ridges near the output end is rounded, and the chamfer radius is R5. The innermost circle of reflection-cancelling metal ridges is the first circle. The distance between the center of the innermost circle of reflection-cancelling metal ridges (221) and the center O of the radial line middle plate (22) is equal to ρ1. The distance between the center of the nth circle of reflection-cancelling metal ridges (22n) and the center O of the radial line middle plate (22) is equal to ρ n The center of the nth circle of reflection-cancelling metal ridge is aligned with the center of the nth circle of gaps, and the radial spacing between the center of the n-1th circle of reflection-cancelling metal ridge and the center of the nth circle of reflection-cancelling metal ridge is equal to S ρ , which is the same as the radial spacing between the centers of adjacent capsule slot units; the reflection-offsetting metal ridge is used to offset the reflected waves excited by the capsule slot units on each circle of slots on the slot array mouth surface (24); On the surface of the slot array mouth surface (24) close to the output end, metal walls are distributed on both sides of each circle of slots, and the metal walls are in a circular ring shape in the top view of the slot array mouth surface (24); the metal walls are in a rectangular shape in the cross-sectional view along the BB' plane, and the width of the metal wall is w1 and the height is h1; the innermost circle of metal walls (241) is the first circle, and the distance between the center of the innermost circle of metal walls (241) and the center O' of the slot array mouth surface (24) is q1, and the distance between the center of the mth circle of metal walls (24m) and the center O' of the slot array mouth surface (24) is q m , the radial distance between the center of the m-1th metal wall and the center of the mth metal wall is equal to S ρ The number of metal wall turns is one more than the number of slot turns, and the metal wall has a total of N+1 turns, 2≤m≤N+1; two adjacent turns of metal wall are equivalent to a parallel plate waveguide, and N+1 turns of metal wall are equivalent to N parallel plate waveguides; the capsule-shaped slot unit cuts the wall current on the slot array mouth surface (24) in the radial direction, generating a displacement current perpendicular to the slot in the slot, and the changing displacement current generates a radiation electric field, which is -45° with the radial direction, and the radiation electric field is decomposed into equal amplitude and same phase x-direction electric fields E x and the electric field E in the y direction y ; Electric field E in the x direction x and the electric field E in the y direction y After propagating through the metal wall, a 90° phase difference is generated, and the x-direction electric field E with a 90° phase difference x and the electric field E in the y direction y After synthesis, it is equivalent to the circular polarization wave radiating into free space, thus realizing the radiation output of the linear polarization wave converted into the circular polarization wave; The flange (3) is annular and made of metal material, with an outer diameter equal to D6, an inner diameter of D5, and a height of H8; the lower surface of the flange (3) is welded to the surface of the slot array opening (24) close to the output end, and the upper surface of the flange (3) is fixedly connected to the lower surface of the antenna cover (4) by screws; the flange (3) provides mechanical support for the antenna cover (4), withstands vibration and impact of the external environment, and has a great impact on the TE transmitted in the radial line leaky waveguide (2). 11 Mode microwave provides shielding protection to prevent external interference signals from entering the high-power microwave circularly polarized radial line slot array antenna; The antenna radome (4) is disk-shaped, with a diameter equal to D6 and a thickness of H9, and is made of polytetrafluoroethylene. The lower surface of the antenna radome (4) is fixedly connected to the upper surface of the flange (3) by screws; the antenna radome (4) is used to protect the high-power microwave circularly polarized radial line slot array antenna from damage by the external environment.

2. A high-power microwave circularly polarized radial line slot array antenna as claimed in claim 1, characterized in that The diameter D1 of the inner conductor (12) and the inner diameter D2 of the outer conductor (11) of the coaxial waveguide (1) need to satisfy the propagation conditions of the TE11 mode in the coaxial waveguide (1), namely: λ0 is the wavelength of input microwave in free space, Where c is the speed of light in vacuum and f is the input TE 11 The frequency of the mode microwave is D2>D1>0, H1>H3>H2>0; the height of the outer conductor (11) is H1+H2; the height of the inner conductor (12) is H1+H2+H3, H1 is the distance between the surface of the coaxial waveguide (1) close to the input end and the surface of the radial line bottom plate (21) close to the input end, H2 is the thickness of the radial line bottom plate (21), and H3 is the distance between the surface of the radial line bottom plate (21) close to the output end and the surface of the radial line middle plate (22) close to the input end; the cylindrical wall thickness of the outer conductor (11) is S and is 2 to 5 mm.

3. A high-power microwave circularly polarized radial line slot array antenna as claimed in claim 1, characterized in that The chamfer radius R1 of the 45° chamfer at the connection between the outer conductor (11) of the coaxial waveguide and the central through-hole of the radial line bottom plate (21) is greater than 0, and the chamfer radius of the 45° chamfer at the connection between the inner conductor (12) of the coaxial waveguide and the radial line middle plate (22) is R2 > 0.

4. A high-power microwave circularly polarized radial line slot array antenna as claimed in claim 1, characterized in that The outer diameter D6 of the radial line bottom plate (21) of the radial line leaky waveguide (2), the inner diameter D4 of the waveguide wall (25) of the radial line leaky waveguide (2), the inner wall chamfer radius R4, the height H7, and the diameter D3 of the radial line middle plate (22), and the edge chamfer radius R3 satisfy D6 > D4 > D3 > 0, R4 > R3 > 0; the distance H5 between the surface of the radial line middle plate (22) close to the output end and the surface of the slot array aperture (24) close to the input end is less than half of the waveguide wavelength, 0 < H5 < 0.5λ0, the distance H3 between the surface of the radial line bottom plate (21) close to the output end and the surface of the radial line middle plate (22) close to the input end is H3 = H5 > 0, the thickness H4 of the radial line middle plate (22) > 0, H7 = H3 + H4 + H5, and the specific values of D6, D4, D3, R4, R3, H3, H4, and H5 are optimized and designed by the electromagnetic simulation software CST Studio Suit.

5. A high-power microwave circularly polarized radial line slot array antenna as claimed in claim 1, characterized in that The number of slit circles N of the slit array mouth surface (24) satisfies 5≤N≤13, and the radial spacing S of the centers of the capsule-shaped slit units on the slit array mouth surface (24) is ρ =λ0, the circumferential spacing S between the centers of adjacent capsule-shaped gap units Φ =λ0 / 3, λ0 is the wavelength of input microwave in free space, Where c is the speed of light in vacuum and f is the input TE 11 The frequency of the mode microwave, the angle between the capsule-shaped slot unit and the radial direction θ = 45°; the distance ρ1 between the center of the innermost circle of slots and the center of the slot array aperture O' satisfies 0.5λ0<ρ1<1.5λ0; the length L of the nth circle of capsule-shaped slot units n Determined by the electric field distribution of the slot array aperture (24), when the electric field distribution of the slot array aperture (24) satisfies uniform distribution, the normalized equivalent resistance r of the nth circle of slots n satisfy where ρ n is the distance from the center of the nth circle of slots to the center O' of the slot array aperture (24), and ρ n =ρ n-1 +S ρ , 2≤n≤N, from the first circle of gaps to the nth circle of gaps, the length of the capsule-shaped gap unit in each circle of gaps is different, and the length of the capsule-shaped gap unit in the nth circle of gaps is L n As n increases, L1 <L2<…<L n <… <L N The width of the capsule-shaped gap unit in the nth gap is W n Indicates that the width of the capsule-shaped gap units in each circle of gaps is the same, satisfying W1=W2=…=W n =…=W N ; Width W of capsule-shaped gap unit n And the equivalent resistance r n The mathematical relationship of is obtained by simulation with electromagnetic simulation software CST Studio Suit. After determining ρ1 and the total number of gaps N, the distance ρ from the center of the nth gap to the center O' of the gap array surface (24) is n It is also uniquely determined, so the normalized equivalent resistance r of the nth gap is n Calculate and obtain the width W of the gap in the nth circle n ; The depth of the capsule-shaped slit unit is equal to the thickness H6 of the slit array surface (24) satisfies 0 <H6<0.5λ0。 6. A high-power microwave circularly polarized radial line slot array antenna as claimed in claim 1, characterized in that The height h2 of the reflection cancellation metal ridge satisfies 0 < h2 < H5, the width w2 > 0, where H5 is the distance between the surface of the radial line middle plate (22) near the output end and the surface of the slot array aperture (24) near the input end; the chamfer radius R5 of the surface edge of the reflection cancellation metal ridge near the output end is > 0; the specific values of h2, w2, and R5 still need to be optimized and designed by the electromagnetic simulation software CST Studio Suit.

7. A high-power microwave circularly polarized radial line slot array antenna as claimed in claim 1, characterized in that The height h1 of the metal wall distributed on both sides of each circle of gaps satisfies 0 Where c is the speed of light in vacuum and f is the input TE 11 The frequency of the mode microwave, the distance q1 from the center of the innermost metal wall to the center O' of the slot array aperture, the distance q from the center of the mth metal wall to the center O' of the slot array aperture (24) m , the radial distance between the center of the m-1th metal wall and the center of the mth metal wall is equal to S ρ , there is q m =q m-1 +S ρ , 0 <q1<ρ1。​ 8. A high-power microwave circularly polarized radial line slot array antenna as claimed in claim 1, characterized in that The diameter D7 of the short - circuited cylinder (23) satisfies D7 = 2ρ1 - λ0, and 0 < D7 < 2λ0, where λ0 is the free - space wavelength of the input microwave. where c is the speed of light in vacuum, and f is the frequency of the input TE 11 mode microwave.

9. A high-power microwave circularly polarized radial line slot array antenna as claimed in claim 1, characterized in that The inner diameter D5 and height H8 of the flange (3) are determined according to actual needs, satisfying D6>D5>0, H8>2λ0; the thickness H9 of the antenna cover (4) is an integer multiple of λ / 2, where λ is the waveguide wavelength of the microwave when passing through the antenna cover, and Right now where ε r is the relative dielectric constant of the radome dielectric material. When the radome is made of polytetrafluoroethylene, ε r =2.55, K is a positive integer, λ0 is the wavelength of input microwave in free space, Where c is the speed of light in vacuum and f is the input TE 11 The frequency of the microwave.

10. A high-power microwave circularly polarized radial line slot array antenna as claimed in claim 1, characterized in that Through the electromagnetic simulation software CST Studio Suit, when D6>D5>D4>D3>D2>D1>0, D7=2ρ1-λ0,0 <D7<2λ0,R1> 0, R2>0, R4>R3>0, R5>0, H1>0, H2>0, H3=H5>0, H4>0, H7=H3+H4+H5,H8>0, where ε r is the relative dielectric constant of the radome dielectric material, K is a positive integer, 0 <w1<λ0, w2>0,0 n <… <L N , W1=W2=…=W n =…=W N , under the condition of S>0, set the antenna radiation efficiency to be greater than 99%, and obtain parameters D1, D2, D3, D4, D5, D6, D7, R1, R2, R3, R4, R5, H1, H2, H3, H4, H5, H6, H7, H8, H9, w1, w2, h1, h2, W n , L n , ρ1, q1, λ0 is the wavelength of the input microwave in free space, Where c is the speed of light in vacuum and f is the input TE 11 The frequency of the microwave mode, L n is the length of the nth capsule-shaped gap unit, W n is the width of the capsule-shaped gap unit in the nth circle of gaps, and S is the thickness of the cylindrical wall of the outer conductor (11).​

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