High power microwave frequency selective surface disc-shaped honeycomb stealth antenna cover

Abstract

The present invention discloses a high-power microwave frequency selective surface disc-type honeycomb stealth antenna cover, and the purpose is to provide an antenna cover with both electromagnetic stealth performance and good electromagnetic transmission characteristics. The present invention is disc-shaped, and is composed of N FSS units that are periodically and evenly arranged. Each FSS unit includes a first dielectric layer, a frequency selective surface layer, and a second dielectric layer. The first dielectric layer, the frequency selective surface layer, and the second dielectric layer are coaxially connected in the order from input to output. The FSS unit is a regular hexagonal prism, and the first dielectric layer and the second dielectric layer are symmetrically loaded on both sides of the frequency selective surface layer. The frequency selective surface layer is composed of a regular hexagonal metal ring and a filling medium. The present invention can selectively transmit or reflect electromagnetic waves within a specific frequency range, reduce the radar scattering cross section of the high-power microwave antenna, and achieve electromagnetic stealth in a specific frequency range, solving the problem that the high-power microwave antenna cannot have both electromagnetic transmission characteristics and electromagnetic stealth functions.

Description

Technical Field

[0001] The present invention belongs to the technical field of microwave frequency band electromagnetic wave control, and in particular relates to a frequency selective surface disc-shaped honeycomb stealth antenna cover applied to the high-power microwave field. 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. 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, high-power microwave antennas currently cannot have both electromagnetic transmission characteristics and electromagnetic stealth functions. Although individual technologies such as electromagnetic stealth and high-power microwave antennas have been widely studied, there is still a lack of in-depth research on antennas with electromagnetic stealth functions in the field of high-power microwaves.

[0003] In current stealth technology, in order to achieve the stealth effect of the target and reduce the detectability of the target, the research mainly focuses on how to reduce the radar cross section (RCS) of the target. Traditional stealth methods include appearance design, coating with absorbing materials, and plasma stealth. However, the antenna is an electromagnetic field radiator. If the traditional stealth method is used to coat the absorbing material or change its shape, it will seriously affect the radiation performance of the antenna. Therefore, under the condition of maintaining the basic working performance of the antenna unchanged, the mainstream method to effectively reduce the radar cross section of the antenna is to use a radome to physically protect the antenna and electromagnetically stealth it.

[0004] Frequency Selective Surface (FSS) can selectively control the transmission, reflection and absorption of electromagnetic waves, thereby achieving the regulation of electromagnetic waves within a specific frequency range, which not only exhibits certain filtering characteristics, but also can reduce RCS, which has greatly promoted the development of stealth technology to a certain extent. Combining the frequency selective surface with the traditional all-dielectric radome can produce an FSS stealth radome that is transparent in the passband and reflective outside the passband, which can effectively reduce the RCS of the target. For every 12dB reduction in RCS, the detectability of the target is reduced by 50%, thereby improving the electromagnetic stealth performance of the target.

[0005] However, the application of FSS in the field of high-power microwaves to achieve stealth will cause the following problems: First, the FSS structure will expand and deform due to thermal effects under the strong electromagnetic radiation of high-power microwaves, which will affect the filtering characteristics and the stability of the incident wave; second, the FSS structure is prone to field enhancement when it resonates. If the power capacity of the FSS structure cannot reach the GW level, the antenna cover will be broken down by the high-power microwave and fail; finally, the FSS structure used in the field of high-power microwaves needs to take into account higher power capacity and electromagnetic field strength, and factors such as the high temperature resistance and dielectric properties of the material need to be considered, which increases the design complexity, processing difficulty and manufacturing cost. At present, there is no public literature involving the application of frequency selective surfaces to the field of high-power microwaves as a technical solution to achieve electromagnetic stealth. Combined with the current development trend of the widespread application of high-power microwave antennas, it is increasingly urgent to develop a antenna cover that can be used in the field of high-power microwaves and has both electromagnetic stealth performance and good transmission characteristics. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a high-power microwave frequency selective surface disc-type honeycomb stealth antenna cover, which has both electromagnetic stealth performance and good electromagnetic transmission characteristics, a power capacity of up to GW level, good polarization stability and incident angle stability, and can selectively transmit or reflect electromagnetic waves within a specific frequency range, without affecting the normal radiation of the high-power microwave antenna within the working frequency band, and can reduce the radar scattering cross section RCS of the high-power microwave antenna within the specific frequency range, thereby solving the problem that the current high-power microwave antenna cover cannot have both electromagnetic transmission characteristics and electromagnetic stealth functions, and the ordinary FSS structure is easily penetrated by strong electromagnetic radiation, and meets the requirements for the development of high-power microwave antennas.

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

[0008] The high-power microwave frequency selective surface disc-type cellular stealth antenna cover provided by the present invention is disc-shaped, has a diameter of d, a thickness of t, and is composed of N FSS units with the same structure arranged periodically and evenly, and the geometric center period spacing between adjacent FSS units is p.

[0009] The end of the high-power microwave frequency selective surface disc-shaped honeycomb stealth antenna cover close to the high-power microwave antenna is defined as the output end, and the end away from the high-power microwave antenna is defined as the input end. Each FSS unit includes a first dielectric layer, a frequency selective surface layer, and a second dielectric layer. The first dielectric layer, the frequency selective surface layer, and the second dielectric layer are coaxially connected in order from input to output. The surface of the first dielectric layer close to the output end is completely in contact with the surface of the frequency selective surface layer close to the input end, and the surface of the frequency selective surface layer close to the output end is completely in contact with the surface of the second dielectric layer close to the input end. An xy two-dimensional coordinate system is established with the surface of the frequency selective surface layer close to the output end as the reference plane, and the center O of the surface of the frequency selective surface layer close to the output end is set as the coordinate origin, and the output end-input end is set as the positive direction of the z-axis, thereby forming an xyz three-dimensional coordinate system, and the subsequent description is based on this coordinate system.

[0010] The high-power microwave frequency selective surface disc-type honeycomb stealth radome is composed of N FSS units in the shape of regular hexagonal prisms arranged periodically and evenly. Each FSS unit is a regular hexagonal prism with a side length of l. The height of the regular hexagonal prism is equal to the thickness t of the radome. The periodic spacing between the geometric centers of adjacent FSS units is p. Define the FSS unit located at the origin O to be in row 0 and column 0. Then the geometric center of all FSS units can be represented by the coordinates (x, y) in the xy plane, and y=1.5·n·l, x is the horizontal coordinate of the coordinate (x, y) corresponding to the geometric center of the FSS unit at different positions, y is the vertical coordinate (x, y), m represents the column number of the FSS unit in the antenna cover, n represents the row number of the FSS unit in the antenna cover, and m and n are integers.

[0011] The first dielectric layer is made of polyethylene material and is a regular hexagonal dielectric substrate with a side length of l and a thickness of t1. Its dielectric constant ε r =2.4; the second dielectric layer is also made of polyethylene material and is a regular hexagonal dielectric substrate with a side length equal to l and a thickness of t3. Its material properties and size are exactly the same as those of the first dielectric layer, that is, t1=t3, and the first dielectric layer and the second dielectric layer are symmetrically loaded on both sides of the frequency selective surface layer.

[0012] The frequency selective surface layer is composed of a regular hexagonal metal ring and a layer of filling medium, and the regular hexagonal metal ring is embedded in the filling medium. The regular hexagonal metal ring is made of aluminum, and its inner ring side length is a, the outer ring side length is b, the metal ring width is w, the metal ring thickness is h, and the side wall edges of the metal ring parallel to the z-axis are chamfered, and the chamfer radius is r1; the metal edges on the two surfaces of the regular hexagonal metal ring parallel to the xy plane close to the input end and the output end are also chamfered, and the chamfer radius of the inner ring edge on both surfaces is r2, and the chamfer radius of the outer ring edge is r3; for processing considerations, the filling medium is made of the same polyethylene material as the first and second dielectric layers, and the dielectric constant ε r =2.4, the filling medium is also a regular hexagonal prism with a side length equal to l, the thickness of the filling medium is equal to the thickness t2 of the frequency selective surface layer, and is equal to the thickness of the metal ring, that is, t2=h.

[0013] When an electromagnetic wave of the passband frequency is incident on the surface of the antenna cover near the input end at a pitch angle θ, since the periodic spacing p of the periodic arrangement of the FSS units is related to the wavelength of the incident electromagnetic wave, when the electromagnetic wave interacts with the frequency selective surface, the FSS unit can resonate only when electromagnetic waves within the working frequency band are incident, allowing the electromagnetic wave to pass through, and electromagnetic waves outside the working frequency band will be reflected or absorbed, thereby achieving a filtering effect on electromagnetic waves of a specific frequency. At the same time, the periodic structure of the frequency selective surface will cause the incident electromagnetic wave to diffract on the surface, and electromagnetic waves of different wavelengths will interfere with each other in different ways, resulting in beam deviation or beam diffusion effects. By designing a periodic structure and geometric shape corresponding to the working frequency band, it is possible to control different frequency components and achieve a filtering effect.

[0014] For the convenience of description, the conditions satisfied by the structural parameters of the above designs are introduced here:

[0015] 1. Loading the first dielectric layer and the second dielectric layer on both sides of the frequency selective surface layer will reduce the resonant frequency of the FSS unit. The corresponding operating frequency of the FSS unit is f0 is the frequency of the incident wave in free space, f0 = c / λ0, where c is the speed of light in a vacuum, λ0 is the wavelength of the incident wave in free space, ε r is the relative dielectric constant of the first dielectric layer and the second dielectric layer, ε r =2.4.

[0016] 2. The thickness h of the regular hexagonal metal ring in the FSS unit should satisfy 0 mm < h < 20 mm. The larger the thickness h of the metal ring, the better the filtering characteristics of the FSS unit. However, if the thickness of the metal ring is too large, it will affect the incident angle stability of the FSS unit and the overall volume and weight of the radome. The width w of the regular hexagonal metal ring should satisfy 0 mm < w < 10 mm. Otherwise, if the width of the metal ring is too small, the structural strength of the radome will be insufficient, and if the width is too large, the transmission loss will be too high. The inner side length a and the outer side length b of the regular hexagonal metal ring satisfy

[0017] 3. In the present invention, the FSS units are arranged periodically, uniformly, and equidistantly in the form of regular hexagonal prisms. The center connection lines of three adjacent FSS units form an equilateral triangle. To avoid the generation of grating lobes, the distance p between adjacent FSS units should be ensured to be less than λ / 2, where λ is the operating wavelength of the incident wave in the medium. Therefore and it satisfies θ is the maximum pitch angle of the incident electromagnetic wave, θ ∈ [0°, 45°]. Therefore, the side length l of the regular hexagon of the FSS unit should satisfy

[0018] 4. The diameter d of the radome is consistent with the aperture of the high-power microwave antenna. The thickness t of the radome is the sum of the thickness t1 of the first dielectric layer, the thickness t2 of the frequency selective surface layer, and the thickness t3 of the second dielectric layer. Loading the first dielectric layer and the second dielectric layer helps to improve the incident angle stability of the FSS unit. However, the thicknesses t1 and t3 of the first dielectric layer and the second dielectric layer should not be too large, otherwise the overall profile of the radome will be too high. Therefore, 0 mm < t1 = t3 < 5 mm, 0 mm < t2 = h < 20 mm, and t = t1 + t2 + t3, 0 mm < t < 30 mm.

[0019] 5. The larger the fillet radius r1 of the side wall edge of the regular hexagonal metal ring in the FSS unit parallel to the z-axis, the higher the power capacity of the radome. However, if r1 is too large, the metal ring tends to be circular, deviating from the original design intention of the regular hexagonal metal ring. Therefore, 0 mm < r1 < 12 mm. When fillet processing is performed on the metal edges of the two surfaces parallel to the xoy plane near the input end and the output end, the sum of the fillet radius r2 of the inner ring edge and the fillet radius r3 of the outer ring edge should be less than the width w of the metal ring, that is, it satisfies r2 + r3 < w. Otherwise, the fillet operation cannot be completed.

[0020] 6. The coordinates (x, y) of the geometric center of the FSS unit in the x-y plane are y = 1.5·n·l, x is the horizontal coordinate of the coordinate (x, y) corresponding to the geometric center of the FSS unit at different positions, y is the vertical coordinate (x, y), m represents the number of columns of the FSS unit in the radome, n represents the number of rows of the FSS unit in the radome, m and n are integers. Due to the limited array surface of the radome, m and n must satisfy Right now

[0021] 7. The radome is composed of N FSS units of the same structure arranged evenly and periodically. N is the maximum number of FSS units with a side length of l that the radome can accommodate under a plane with a diameter of d. If the FSS units have 2|m|+1 columns and 2|n|+1 rows, then N satisfies i is the maximum number of FSS units that can be accommodated in the nth row. i is an integer and an even number, 0≤i≤2|m|+1, and the distance from the i-th FSS unit in the nth row to the center O must be less than the radius of the radome, so Right now

[0022] Through the electromagnetic simulation software CST Studio Suit, when 0<a<b is satisfied, ε r =2.4,0mm <h<20mm, 0mm <t1=t3<5mm,0mm<t2=h<20mm,t=t1+t2+t3,0mm<t<30mm,0mm<r1<12mm,r2+r3<w,0mm<w<10mm, y=1.5·n·l, m and n are integers, Under the condition that i is an integer and an even number, d is consistent with the aperture of the high-power microwave antenna, the FSS unit resonance is set at the operating frequency of the high-power microwave antenna, the reflection coefficient S11<-20dB at the operating frequency, the insertion loss is less than 0.5dB, and the power capacity reaches the GW level as the optimization goal. The parameters are optimized through the scanning parameter function of the simulation software, and the optimal and accurate values ​​of parameters a, b, d, h, i, l, p, r1, r2, r3, t, t1, t2, t3, w, and N can be obtained.

[0023] The working process of the present invention is:

[0024] When electromagnetic waves within the working frequency band of the high-power microwave antenna are incident on the surface of the antenna cover near the input end at a pitch angle θ, each FSS unit in the antenna cover resonates, so that the incident waves of vertical polarization and horizontal polarization can generate transmission coefficient waveforms with stable center frequency and bandwidth in the corresponding incident surface as the incident angle increases, and the incident waves are transmitted from the surface near the output end and transmitted to the high-power microwave antenna; when electromagnetic waves outside the working frequency band of the high-power microwave antenna are incident on the surface of the antenna cover near the input end, the FSS unit can reflect or scatter the incident electromagnetic waves to other directions, and electromagnetic waves outside the working frequency band cannot be transmitted normally to the high-power microwave antenna. Therefore, the high-power microwave antenna can transmit and receive electromagnetic waves normally within the working frequency band, and the electromagnetic waves are cut off outside the working frequency band, thereby achieving a stable filtering function.

[0025] At the same time, the periodically arranged FSS units can interact with the wavelength of the incident electromagnetic wave. When the wavelength of the incident wave matches the periodic spacing of the FSS unit, the metal conductor or dielectric structure in the FSS unit will exhibit resonance, causing an enhancement effect of the local electromagnetic field, and the FSS unit will selectively transmit or reflect the electromagnetic wave of this wavelength; while for electromagnetic waves of other wavelengths, the FSS unit will exhibit a higher reflectivity or absorption rate, reducing the reflected echo in other frequency bands, thereby achieving the effect of reducing the RCS of the high-power microwave antenna within a specific frequency range and reducing the possibility of being detected by radar, thereby realizing the function of electromagnetic stealth.

[0026] Compared with the prior art, the present invention can achieve the following technical effects:

[0027] 1. The present invention adopts the FSS unit as the basic unit of the antenna cover. Due to the filtering characteristics of the frequency selective surface itself, when electromagnetic waves propagate in the FSS antenna cover, only waves in a specific frequency band can be transmitted, while waves in other frequency bands will be efficiently reflected or absorbed, so that the antenna cover can achieve a selective transmission effect of transmitting waves within the working frequency band and cutting off waves outside the working frequency band.

[0028] 2. The present invention can reduce the radar cross section of a high-power microwave antenna within a specific frequency range without affecting the transmission performance within the passband of the high-power microwave antenna, thereby reducing the possibility of being detected by radar and achieving the function of electromagnetic stealth within a specific frequency range.

[0029] 3. The FSS unit in the present invention is a bandpass unit. The FSS units are arranged uniformly, equidistantly and periodically to avoid the generation of grating lobes. At the same time, the FSS unit has high transmittance at the operating frequency of the high-power microwave antenna and high reflectivity at other frequencies.

[0030] 4. The present invention rounds off all edges of the regular hexagonal metal ring in the FSS unit to avoid excessive concentration of the electric field at the sharp points of the metal, thereby effectively improving the overall power capacity of the present invention and can be applied to high-power microwave radiation antennas.

[0031] 5. The present invention has the characteristics of good polarization performance, high incident angle stability and large power capacity, which meets the requirements that high-power microwave antennas can effectively transmit electromagnetic waves.

[0032] 6. The present invention is highly flexible and can adjust the size of the antenna cover according to the aperture size of the high-power microwave antenna. It can still maintain a stable electromagnetic stealth function and good filtering characteristics within a certain size range, which meets the requirements for the development of high-power microwave antennas. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the overall structure of the high-power microwave frequency selective surface disc-shaped honeycomb stealth antenna cover of the present invention. Figure 1 (a) is the overall isometric view of the radome. Figure 1 (b) Yes Figure 1 (a) A magnified partial view.

[0034] Figure 2 It is a schematic diagram of the layered structure of a high-power microwave frequency selective surface disc-type honeycomb stealth antenna cover.

[0035] Figure 3 This is a schematic diagram of the FSS unit arrangement pattern.

[0036] Figure 4 This is a schematic diagram of the FSS unit structure. Figure 4 (a) is a schematic diagram of the hierarchical structure of the FSS unit. Figure 4 (b) is the isometric view of the regular hexagonal metal ring in the FSS unit.

[0037] Figure 5 This is the curve diagram of the FSS unit S parameter simulation results. Figure 5 (a) is the S11 curve of the FSS unit when the TE wave and TM wave are incident at θ = 0° respectively. Figure 5 (b) is the S21 curve diagram of the FSS unit when the TE wave and TM wave are incident at θ=0° respectively.

[0038] Figure 6 It is the S parameter simulation result curve diagram of the FSS unit when the incident wave is incident at the pitch angle θ of 0°, 15°, 30°, and 45° respectively. Figure 6 (a) is the S11 curve of the FSS unit when the TM wave is incident at an elevation angle θ of 0°, 15°, 30°, and 45° respectively. Figure 6(b) is the S21 curve of the FSS unit when the TM wave is incident at pitch angles θ of 0°, 15°, 30°, and 45° respectively.

[0039] Figure 7 The electric field distribution diagram of the FSS unit array in an infinite plane when the TE wave and TM wave are incident at θ = 0°, Figure 7 (a) is the electric field distribution diagram of the FSS unit array when the TE wave is incident at θ = 0°. Figure 7 (b) is the electric field distribution diagram of the FSS unit array when the TM wave is incident at θ=0°.

[0040] Figure 8 It is a curve chart of simulation results of the RCS reduction effect of the high-power microwave frequency selective surface disc-type honeycomb stealth antenna cover and the all-dielectric antenna cover of the present invention on the high-power microwave antenna. DETAILED DESCRIPTION

[0041] The specific implementation of the present invention is further described below in conjunction with the drawings and examples.

[0042] Figure 1 It is a schematic diagram of the overall structure of the high-power microwave frequency selective surface disc-shaped honeycomb stealth antenna cover of the present invention. Figure 1 (a) is an overall isometric view of the high-power microwave frequency selective surface disc-shaped honeycomb stealth radome. Figure 1 (b) Yes Figure 1 (a) is a partial enlarged view. Figure 1 As shown, the high-power microwave frequency selective surface disc-type honeycomb stealth antenna cover provided by the present invention is disc-shaped, with a diameter of d, which is the same as the diameter of the high-power microwave antenna, and a thickness of t. It is composed of N FSS units with the same structure arranged periodically and evenly at equal intervals, and the geometric center period interval of adjacent FSS units is p. N is a positive integer.

[0043] Figure 2 The figure is a schematic diagram of the layered structure of a high-power microwave frequency selective surface disc-shaped honeycomb stealth antenna cover. Figure 2As shown, the end of the antenna cover close to the high-power microwave antenna is defined as the output end, and the end away from the high-power microwave antenna is defined as the input end. Each FSS unit includes a first dielectric layer 1, a frequency selective surface layer 2, and a second dielectric layer 3, and their thicknesses are t1, t2, and t3, respectively, and t1+t2+t3=t. The first dielectric layer 1, the frequency selective surface layer 2, and the second dielectric layer 3 are coaxially connected in order from input to output. The surface of the first dielectric layer 1 close to the output end is completely in contact with the surface of the frequency selective surface layer 2 close to the input end, and the surface of the frequency selective surface layer 2 close to the output end is completely in contact with the surface of the second dielectric layer 3 close to the input end. An xy two-dimensional coordinate system is established with the surface of the frequency selective surface layer 2 close to the output end as the reference plane, and the center O of the surface of the frequency selective surface layer 2 close to the output end is set as the coordinate origin, and the output end-input end is set as the positive direction of the z-axis, thereby forming an xyz three-dimensional coordinate system.

[0044] like Figure 2 As shown, when the electromagnetic wave of the passband frequency (i.e., the incident wave) is incident on the surface of the antenna cover close to the input end at a pitch angle θ, each FSS unit of the antenna cover generates resonance, so that the vertically polarized and horizontally polarized incident waves can generate transmission coefficient waveforms with stable center frequency and bandwidth in the corresponding incident plane as the incident angle increases, and are transmitted from the other side surface, thereby realizing a stable filtering function.

[0045] Figure 3 This is a schematic diagram of the FSS unit arrangement. Figure 3 As shown in FIG. 1 , the high-power microwave frequency selective surface disk-type honeycomb stealth radome is composed of N FSS units arranged periodically and evenly. Each FSS unit is a regular hexagonal prism with a side length of l. The height of the regular hexagonal prism is equal to the thickness t of the radome. The periodic spacing between the geometric centers of adjacent FSS units is p. Define the FSS unit located at the origin O to be in row 0 and column 0. Then the geometric center of all FSS units can be represented by the coordinates (x, y) in the xy plane, and y=1.5·n·l, x is the horizontal coordinate of the coordinate (x, y) corresponding to the geometric center of the FSS unit at different positions, y is the vertical coordinate (x, y), m represents the column number of the FSS unit in the antenna cover, n represents the row number of the FSS unit in the antenna cover, and m and n are integers.

[0046] Figure 4 This is a schematic diagram of the FSS unit structure. Figure 4 (a) is a schematic diagram of the hierarchical structure of the FSS unit. Figure 4 (b) is the isometric view of the regular hexagonal metal ring in the FSS unit. Figure 4As shown in (a), the first dielectric layer 1 is made of polyethylene material and is a regular hexagonal dielectric substrate with a side length of l and a thickness of t1. The dielectric constant of the polyethylene material is ε r =2.4; the second dielectric layer 3 is also made of polyethylene material and is a regular hexagonal dielectric substrate with a side length of l and a thickness of t2. Its material properties and size are completely consistent with the first dielectric layer 1, that is, t1=t2, and the first dielectric layer 1 and the second dielectric layer 3 are symmetrically loaded on both sides of the frequency selective surface layer 2. The frequency selective surface layer 2 is composed of a regular hexagonal metal ring 4 and a layer of filling medium, and the regular hexagonal metal ring 4 is embedded in the filling medium. The regular hexagonal metal ring 4 is made of aluminum, with an inner ring side length of a, an outer ring side length of b, a ring width of w, and a thickness of h; the side wall edges of the regular hexagonal metal ring 4 parallel to the z-axis are chamfered, and the chamfer radius is r1; the metal edges on the two surfaces of the regular hexagonal metal ring 4 parallel to the xy plane close to the input end and the output end are also chamfered, and the chamfer radius of the inner ring edges on both surfaces is r2, and the chamfer radius of the outer ring edges is r3; for processing considerations, the filling medium uses the same polyethylene material as the first medium layer and the second medium layer, and the filling medium is also a regular hexagonal prism with a side length equal to l. The thickness of the filling medium is equal to the thickness t3 of the frequency selective surface layer, and is equal to the thickness h of the regular hexagonal metal ring 4, that is, t2=h.

[0047] Example 1

[0048] The specific design dimensions of Example 1 of a high-power microwave frequency selective surface disc-type honeycomb stealth antenna cover for 4.3 GHz (corresponding to a microwave wavelength of 69.72 mm) are given below:

[0049] At this operating frequency, the diameter of the high-power microwave frequency selective surface disc-shaped honeycomb stealth antenna cover is d = 800mm, the thickness is t = 15mm, the number of FSS units is N = 241, the side length of each FSS unit is l = 27.43mm, the thickness of the regular hexagonal prism is equal to the thickness of the antenna cover t = 15mm, and the geometric center period spacing of adjacent FSS units is The thickness of the first dielectric layer 1 is t1=3mm, the thickness of the frequency selective surface layer 2 is t3=9mm, and the thickness of the second dielectric layer 3 is t2=3mm. The regular hexagonal metal ring 4 is made of aluminum, with an inner ring side length a=17.5mm, an outer ring side length b=21.66mm, a ring width w=3.6mm, and a thickness h=9.0mm. The side wall edges of the regular hexagonal metal ring 4 parallel to the z-axis are chamfered, and the chamfer radius is r1=8.0mm; the metal edges of the regular hexagonal metal ring 4 on the two surfaces parallel to the xy plane close to the input end and the output end are also chamfered, and the chamfer radius of the inner ring edge on the two surfaces is r2=1.5mm, and the chamfer radius of the outer ring edge is r3=2.0mm; for processing considerations, the filling medium is made of the same polyethylene material as the first dielectric layer 1 and the second dielectric layer 3, and the dielectric constant ε r =2.4, the filling medium is also a regular hexagonal prism with a side length of l = 27.43 mm, and the thickness of the filling medium is equal to the thickness of the frequency selective surface layer, t3 = h = 9.0 mm.

[0050] Example 1 The S parameter simulation results of the FSS unit in the high-power microwave frequency selective surface disk-type honeycomb stealth antenna cover with a center frequency of 4.3 GHz are as follows Figure 5 As shown, Figure 5 (a) is the S11 curve of the FSS unit when the TE wave and TM wave are incident at θ = 0° respectively. Figure 5 (a) The horizontal axis is the frequency, and the vertical axis is the FSS unit reflection coefficient S11; Figure 5 (b) is the S21 curve of the FSS unit when the TE wave and TM wave are incident at θ = 0° respectively. Figure 5 (b) The horizontal axis is the frequency, and the vertical axis is the FSS unit transmission coefficient S21. Figure 5 It can be seen that because the FSS unit is a regular hexagon with extremely high geometric symmetry, the S parameter curves of the TE wave and the TM wave almost completely overlap, indicating that the FSS unit has excellent polarization stability.

[0051] The S parameter simulation results of the FSS unit when the incident wave is incident at a pitch angle θ of 0°, 15°, 30°, and 45° are shown in the figure below: Figure 6 As shown, Figure 6 (a) is the S11 curve of the FSS unit when the TM wave is incident at an elevation angle θ of 0, 15°, 30°, and 45° respectively. Figure 6 (a) The horizontal axis is the frequency, and the vertical axis is the FSS unit reflection coefficient S11; Figure 6 (b) is the S21 curve of the FSS unit when the TM wave is incident at an elevation angle θ of 0°, 15°, 30°, and 45° respectively. Figure 6 (b) The horizontal axis is the frequency, and the vertical axis is the FSS unit transmission coefficient S21. Figure 6It can be seen that the FSS unit is insensitive to changes in the incident angle, and the S parameters have a consistent trend within the working frequency band and a high degree of coincidence, indicating that the FSS unit has good incident angle stability in the range of θ∈[0°,45°].

[0052] Figure 7 The electric field distribution diagram of the FSS unit in the infinite plane is simulated when the TE wave and TM wave are incident at θ = 0°. Figure 7 (a) is the electric field distribution diagram of the FSS unit array when the TE wave is incident at θ = 0°. Figure 7 (b) is the electric field distribution diagram of the FSS unit array when the TM wave is incident at θ = 0°. Figure 7 It can be seen that the electric field is mainly concentrated at the junction of the regular hexagonal metal ring 4 and the filling medium, and the electric field distribution inside the regular hexagonal metal ring 4 is relatively uniform. When the TE wave is incident at θ=0°, the maximum value of the electric field strength after the FSS unit array is 1550.44V / m; when the TM wave is incident at θ=0°, the maximum value of the electric field strength is 1766.53V / m. When the injection power is 0.5W, according to the dielectric window surface breakdown threshold of 60kV / cm, the power capacity of the present invention when the TE wave is incident is 3.83GW / m when working at 4.3GHz. 2 , the power capacity when TM wave is incident is 2.95GW / m 2 , all reaching the GW level, meeting the power capacity requirements of high-power microwave strong electromagnetic radiation.

[0053] The frequency selective surface layer 2 in the high-power microwave frequency selective surface disk-type honeycomb stealth antenna cover of the present invention is replaced with a dielectric layer with a thickness of t3, and the dielectric material is selected from polyethylene that is the same as the first dielectric layer 1 and the second dielectric layer 3, thereby forming a full dielectric antenna cover. The full dielectric antenna cover and Example 1 are respectively combined with the same high-power microwave antenna for simulation, and the simulation result curve of the full dielectric antenna cover and Example 1 for the RCS reduction effect of the high-power microwave antenna is obtained, as shown in FIG. Figure 8 As shown. Figure 8 It can be seen that compared with the all-dielectric antenna cover, the high-power microwave frequency selective surface disc-type honeycomb stealth antenna cover of Example 1 of the present invention has a significant reduction in RCS within the frequency band of 8GHz-10GHz, with an average RCS reduction of 5.17dB within 8GHz-10GHz, and a maximum RCS reduction of 19.58dB at 8.8GHz. This shows that the FSS unit structure design of Example 1 is better, and the overall performance of Example 1 is better. It can effectively selectively reflect electromagnetic waves, play a role in reducing the RCS of a single station within a specific frequency range, reduce the detectability of high-power microwave antennas, and have a certain electromagnetic stealth effect.

[0054] The present invention has both electromagnetic stealth performance and good electromagnetic transmission characteristics, the power capacity can reach the GW level, it has good polarization stability and incident angle stability, and can selectively transmit or reflect electromagnetic waves within a specific frequency range, which does not affect the normal radiation of the high-power microwave antenna within the working frequency band, and can reduce the radar scattering cross-section of the high-power microwave antenna within the specific frequency range. It can solve the problem that the current high-power microwave antenna cannot have both electromagnetic transmission characteristics and electromagnetic stealth functions, and the ordinary FSS structure is easily penetrated by strong electromagnetic radiation. The present invention is highly flexible and can adjust the size of the antenna cover according to the high-power microwave antennas with different array sizes, which meets the requirements for the development of high-power microwave antennas.

[0055] 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 frequency selective surface disc-shaped honeycomb stealth antenna cover, characterized in that The high-power microwave frequency selective surface disc-type honeycomb stealth antenna cover is disc-shaped, with a diameter d that is the same as the high-power microwave antenna aperture and a thickness of t. It is composed of N FSS units with the same structure that are periodically and evenly arranged at equal intervals. The center lines of three adjacent FSS units form an equilateral triangle, and the periodic spacing of the geometric centers of adjacent FSS units is p; N is a positive integer; The high-power microwave frequency selective surface disk-shaped honeycomb stealth antenna cover is defined as an output end at one end close to the high-power microwave antenna, and an input end at one end away from the high-power microwave antenna; each FSS unit comprises a first dielectric layer (1), a frequency selective surface layer (2) and a second dielectric layer (3), and the thicknesses thereof are t1, t2 and t3 respectively, and t1+t2+t3=t; the first dielectric layer (1), the frequency selective surface layer (2) and the second dielectric layer (3) are coaxially connected in the order from input to output, and the surface of the first dielectric layer (1) close to the output end is completely in contact with the surface of the frequency selective surface layer (2) close to the input end, and the surface of the frequency selective surface layer (2) close to the output end is completely in contact with the surface of the second dielectric layer (3) close to the input end; When the electromagnetic wave of the passband frequency is incident on the surface of the radome near the input end at a pitch angle θ, each FSS unit of the radome will resonate, so that the incident waves of vertical polarization and horizontal polarization can generate transmission coefficient waveforms with stable center frequency and bandwidth in the corresponding incident plane as the incident angle increases, and transmit out from the other side surface, realizing a stable filtering function; Each FSS unit is a regular hexagonal prism, the side length of the regular hexagon is l, the height of the regular hexagonal prism is equal to t, and the geometric center period spacing of adjacent FSS units is p. A two-dimensional xy coordinate system is established with the surface of the frequency selective surface layer (2) near the output end as a reference plane, the center O of the surface of the frequency selective surface layer (2) near the output end is set as the coordinate origin, and the output end-input end is set as the positive direction of the z-axis, thereby forming an xyz three-dimensional coordinate system; the FSS unit located at the coordinate origin O is defined as being in the 0th row and the 0th column, and the geometric centers of all FSS units are represented by coordinates (x, y) in the xy plane, and there is y=1.5·n·l, x is the abscissa of the coordinates (x, y) corresponding to the geometric center of the FSS unit at different positions, y is the ordinate of (x, y), m represents the column number of the FSS unit in the radome, n represents the row number of the FSS unit in the radome, and m and n are integers; The first dielectric layer (1) is made of polyethylene material and is a regular hexagonal dielectric substrate with a side length of l and a thickness of t1; The second dielectric layer (3) is also made of polyethylene material and is a regular hexagonal dielectric substrate with a side length of l and a thickness of t3. Its material properties and size are completely consistent with those of the first dielectric layer (1), that is, t1=t3, and the first dielectric layer (1) and the second dielectric layer (3) are symmetrically loaded on both sides of the frequency selective surface layer (2); the frequency selective surface layer (2) is composed of a regular hexagonal metal ring (4) and a layer of filling medium, and the regular hexagonal metal ring (4) is embedded in the filling medium; the regular hexagonal metal ring (4) has an inner ring side length of a, an outer ring side length of b, a ring width of w, and a thickness of h; the side wall edges of the regular hexagonal metal ring (4) parallel to the z-axis are chamfered, and the chamfer radius is r1; the metal edges on the two surfaces of the regular hexagonal metal ring (4) parallel to the xy plane close to the input end and close to the output end are also chamfered, and the chamfer radius of the inner ring edge on both surfaces is r2, and the chamfer radius of the outer ring edge is r3; The filling medium is made of the same polyethylene material as the first and second dielectric layers. The filling medium is a regular hexagonal prism with a side length of l. The thickness of the filling medium is equal to the thickness t2 of the frequency selective surface layer and is equal to the thickness h of the regular hexagonal metal ring (4), that is, t2=h.

2. The high-power microwave frequency selective surface disc-shaped honeycomb stealth antenna cover as claimed in claim 1, characterized in that The dielectric constant ε of the polyethylene material r =2.4; the regular hexagonal metal ring (4) is made of aluminum.

3. The high-power microwave frequency selective surface disc-shaped honeycomb stealth antenna cover as claimed in claim 1, characterized in that The FSS unit corresponds to the operating frequency f0 is the frequency of the incident wave in free space, f0 = c / λ0, where c is the speed of light in a vacuum, λ0 is the wavelength of the incident wave in free space, ε r is the relative dielectric constant of the polyethylene material used in the first dielectric layer (1).

4. The high-power microwave frequency selective surface disc-shaped honeycomb stealth antenna cover as claimed in claim 1, characterized in that Spacing between adjacent FSS units and λ0 is the wavelength of the incident wave in free space, ε r is the relative dielectric constant of the polyethylene material used in the first dielectric layer (1), λ is the working wavelength of the incident wave in the medium, θ is the maximum pitch angle of electromagnetic wave incidence, θ∈[0°,45°], and the side length l of the FSS unit regular hexagon satisfies 5. The high-power microwave frequency selective surface disc-shaped honeycomb stealth antenna cover as claimed in claim 1, characterized in that The thickness h of the regular hexagon metal ring (4) in the FSS unit satisfies 0 mm < h < 20 mm, and the ring width w of the regular hexagon metal ring (4) satisfies 0 mm < w < 10 mm; the inner side length a and the outer side length b of the regular hexagon metal ring (4) satisfy 6. The high-power microwave frequency selective surface disc-shaped honeycomb stealth antenna cover as claimed in claim 1, characterized in that The thickness t of the high-power microwave frequency selective surface disc-type honeycomb stealth radome satisfies 0 mm < t < 30 mm, and the thicknesses t1 of the first dielectric layer (1), t2 of the frequency selective surface layer (2), and t3 of the second dielectric layer (3) satisfy 0 mm < t1 = t3 < 5 mm, 0 mm < t2 = h < 20 mm, and t = t1 + t2 + t3.

7. The high-power microwave frequency selective surface disc-shaped honeycomb stealth antenna cover as claimed in claim 1, characterized in that For the FSS unit, the fillet radius r1 of the side wall edges of the regular hexagonal metal ring (4) parallel to the z-axis satisfies 0 mm < r1 < 12 mm. When fillet processing is performed on the metal edges on the two surfaces close to the input end and the output end parallel to the xoy plane, the inner ring edge fillet radius r2 and the outer ring edge fillet radius r3 satisfy r2 + r3 < w.

8. The high-power microwave frequency selective surface disc-shaped honeycomb stealth antenna cover as claimed in claim 1, characterized in that The coordinates (x, y) of the geometric center of the FSS unit in the xy plane satisfy y = 1.5·n·l, x is the horizontal coordinate of the coordinate (x, y) corresponding to the geometric center of the FSS unit at different positions, y is the vertical coordinate (x, y), m represents the number of columns of the FSS unit in the radome, n represents the number of rows of the FSS unit in the radome, m and n are integers, and m and n must satisfy When the FSS units have 2|m|+1 columns and 2|n|+1 rows, the maximum number of FSS units with a side length of l that can be accommodated by the high-power microwave frequency selective surface disc-shaped cellular stealth antenna cover under the array surface with a diameter of d is i is the maximum number of FSS units that can be accommodated in the nth row. i is an integer and an even number, and satisfies 0≤i≤2|m|+1 and 9. The high-power microwave frequency selective surface disc-shaped honeycomb stealth antenna cover according to any one of claims 1 to 8, characterized in that When 0<a<b, ε r =2.4,0mm <h<20mm, θ∈[0°,45°], 0mm <t1=t3<5mm,0mm<t2=h<20mm,t=t1+t2+t3,0mm<t<30mm,0mm<r1<12mm,r2+r3<w,0mm<w<10mm, y=1.5·n·l, m and n are integers, 0≤i≤2|m|+1, Under the condition that i is an integer and an even number, d is consistent with the aperture of the high-power microwave antenna, the FSS unit resonance is set at the operating frequency of the high-power microwave antenna, the reflection coefficient S11<-20dB at the operating frequency, the insertion loss is less than 0.5dB, and the power capacity reaches the GW level as the optimization goal. The scanning parameter function of the simulation software is used to optimize each parameter to obtain the optimal and precise values ​​of parameters a, b, d, h, i, l, p, r1, r2, r3, t, t1, t2, t3, w, and N.

10. The high-power microwave frequency selective surface disc-shaped honeycomb stealth antenna cover as claimed in claim 9, characterized in that The simulation software is the electromagnetic simulation software CST Studio Suit.

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