CN118099758B - Low-absorption high-transmission radome frequency selection surface based on topological coding - Google Patents
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- 239000002184 metal Substances 0.000 claims abstract description 71
- 229910052751 metal Inorganic materials 0.000 claims abstract description 71
- 239000000758 substrate Substances 0.000 claims abstract description 30
- 239000000463 material Substances 0.000 claims description 16
- 230000010287 polarization Effects 0.000 claims description 10
- 239000011159 matrix material Substances 0.000 claims description 7
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- 238000004422 calculation algorithm Methods 0.000 description 2
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- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
- H01Q15/0006—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices
- H01Q15/0086—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices said selective devices having materials with a synthesized negative refractive index, e.g. metamaterials or left-handed materials
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q1/00—Details of, or arrangements associated with, antennas
- H01Q1/42—Housings not intimately mechanically associated with radiating elements, e.g. radome
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Abstract
The invention discloses a low-absorption high-permeability radome frequency selective surface based on topological coding, which belongs to the field of electromagnetic metamaterials, is applied to a constituent unit of a radome, the novel high-voltage power amplifier comprises a first layer of loss layer, a second layer of dielectric layer and a third layer of wave-transmitting layer, wherein the first layer comprises a first metal layer and a dielectric substrate, and the third layer comprises a second metal layer, a dielectric substrate, a third metal layer, a dielectric substrate and a fourth metal layer. The first metal layer adopts topological structure discretization to represent the configuration of the metal patch, the second metal layer is a circular metal patch, the third metal layer is an aperture type metal patch structure with circular aperture, and the fourth metal layer is a circular metal patch which is the same as the second metal layer. The invention adopts the topological coding idea to discretize the metal patch structure, and simultaneously uses the second-order frequency selective surface to further widen the passband bandwidth, thereby realizing the electromagnetic performance of low-frequency wave absorption and high-frequency wave transmission.
Description
Technical Field
The invention belongs to the technical field of electromagnetic metamaterials, and particularly relates to a low-absorption high-transmission radome frequency selection surface based on topological coding.
Background
The frequency selective surface (Frequency Selective Surface, FSS) is a periodic surface. In general, a complete frequency selective surface is generally structured by a dielectric substrate and a two-dimensional periodic array of metals uniformly distributed on the surface. When an electromagnetic wave is incident on the frequency selective surface, the metal array of the FSS surface resonates with the electromagnetic wave, so that the incident electromagnetic wave can penetrate the frequency selective surface. Meanwhile, due to the distribution of the metal array on the frequency selective surface and the property of the metal array, the incident electromagnetic wave can be completely transmitted, partial transmission or reflection enables the frequency selective surface to show different working characteristics, the frequency selective surface is often used for manufacturing radomes in practical application with the characteristics of band-pass or band-stop filters, the electromagnetic wave in the transmission band and the electromagnetic wave outside the reflection band, but the reflected electromagnetic wave is often detected and received by other base stations, so that the traditional frequency selective radome only has a remarkable effect on the RCS reduction of a single station, and the reflected electromagnetic wave is extremely easy to be found by a double-station or multi-station detection network, thereby greatly threatening the safety of a fight platform.
Based on this, researchers have intensively studied to propose a frequency selective absorber (Frequency Selective Rasorber, FSR) that integrates a conventional FSS Circuit with a simulated absorber (Circuit-Analog Absorber, CAA) to form a new periodic electromagnetic structure, also called an absorptive frequency selective surface (Absorptive Frequency Selective Surface, AFSS), which is commonly used to reduce a two-station or multi-station RCS.
However, with the gradual completion of functions, the structural complexity and the difficulty of electromagnetic performance analysis of the material are increased, and meanwhile, the difficulty is increased gradually due to the dependence of experience of modeling design, which brings great obstacle to the design of researchers. Therefore, an automatic intelligent design method is urgently needed to design the whole structure of the metamaterial, and meanwhile, the electromagnetic simulation time is required to be reduced, so that the manufacturing period is shortened.
Based on the method, the invention designs a low-absorption high-transmission radome frequency selection surface based on topological coding.
Disclosure of Invention
The invention aims to solve the problems that the monitoring of a multi-station base station cannot be dealt with due to out-of-band reflection electromagnetic waves in a traditional structure, the traditional design effect is poor, the structure is complex and experience is dependent.
In order to achieve the above purpose, the present invention adopts the following technical scheme: the low-absorption high-transmission radome frequency selective surface based on the topological coding is characterized in that the frequency selective surface unit structure is a first metal layer, a first dielectric substrate, a dielectric layer, a second metal layer, a second dielectric substrate, a third metal layer, a third dielectric substrate and a fourth metal layer from top to bottom.
The first metal layer and the first dielectric substrate are used together for consuming internally reflected electromagnetic waves in a low-frequency band. Wherein the first metal layer is in a topological coding structure, and the size of the coding matrix is 16 multiplied by 16, and 1 and 0 represent the existence of the small metal patch. The first metal layer is divided into four central symmetrical sub-blocks by the central line of the square boundary, each sub-block is symmetrical along the diagonal, the part to be actually encoded is the diagonal and the symmetrical part, the matrix size representing the sub-block is only 8 multiplied by 8, and the length of the part to be actually encoded in the matrix is only (1+8) multiplied by 8/2.
The second metal layer, the second medium substrate, the third metal layer, the third medium substrate and the fourth metal layer form a second-order band-pass frequency selective surface together and are used for selectively transmitting high-frequency electromagnetic waves and reflecting low-frequency electromagnetic waves, so that the second-order band-pass frequency selective surface has wider wave-transmitting bandwidth and better out-of-band rejection performance. The second metal layer and the fourth metal layer are round metal patches with the same size, and the third metal layer is a round aperture metal patch.
The dielectric layer supports the whole structure for improving the physical strength of the material, and simultaneously simulates the transmission of electromagnetic waves in free space, wherein the dielectric layer is made of a specific material and has a thickness far greater than that of a dielectric substrate.
Further described as the technical scheme is as follows: the period of the integral material, the diameters of the circular patch and the circular aperture, and the thicknesses of the dielectric substrate and the dielectric layer are all expressed by binary numbers, and the binary numbers and the topological codes of the first metal layer form a '01' code matrix which is input into an evolutionary algorithm together for iterative optimization, so that the flexibility and the stability of the design are further improved.
In summary, by adopting the technical scheme, the beneficial results of the invention are as follows: according to the invention, the structure of the metal layer is flexibly represented and designed in a mode of combining topological coding and an evolutionary algorithm, and the wave-transmitting and wave-absorbing performance of the whole structure is further improved by using the second-order band-pass frequency selective surface, so that the problems that the traditional design depends on experience, the structure is complex and difficult to design are solved, the designed structure is simple, the polarization stability is good, and the low-absorption and high-transmission electromagnetic performance is realized.
Drawings
FIG. 1 is a schematic diagram of a low-absorption high-transmission radome frequency selective surface based on topological coding and ideal frequency response;
FIG. 2 is an equivalent circuit model of a low-absorption high-transmission radome frequency selective surface based on topological coding;
FIG. 3 is a block diagram of a topology coding based low-absorption high-transmission radome frequency selective surface unit;
fig. 4 is a schematic diagram of a topology coding configuration of a first metal layer of a frequency selective surface of a radome with low absorption and high transmission based on topology coding;
FIG. 5 shows the return loss and the insertion loss of the low-absorption high-transmission radome frequency selective surface at 0-10 GHz based on topological coding;
FIG. 6 shows the wave absorption rate and wave transmission rate of the low-absorption high-transmission radome frequency selective surface at 0-10 GHz based on topological coding;
Detailed Description
In the description of the present invention, it should be understood that the terms "center", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention.
It should be noted that each layer of the invention belongs to a central symmetry structure for a plane, and has the characteristic of insensitive polarization, so that TE and TM polarizations have little difference, and only simulation results under TE polarization are shown in the illustration.
Referring to fig. 1, electromagnetic waves irradiate into the suction-penetration integrated material from above, impedance matching is carried out between the frequency selective surface and the free space in a low-frequency band, the electromagnetic waves irradiate into the metamaterial, and are reflected back when reaching the bottom frequency selective surface through a medium, and the suction function is realized by the loss layer in a surface loss structure and the medium loss electromagnetic waves; in the high frequency band, the material is transparent to electromagnetic waves, and the electromagnetic waves can be transmitted almost unimpeded with little absorption and reflection.
Referring to fig. 1 and 2 in combination, fig. 2 is an equivalent circuit diagram of a penetration-integrated metamaterial, and when an electromagnetic wave is incident on a material, the electromagnetic wave is absorbed, transmitted and reflected, and good penetration and absorption properties are desired, so that reflection of the electromagnetic wave on the material is reduced, that is, a reflection coefficient Γ is reduced, and therefore, a good penetration property of the penetration-integrated frequency selective surface is desired, and good impedance matching with a spatial electromagnetic wave is required. As shown in the figure, Z R is the equivalent impedance of the loss layer, Z B is the equivalent impedance of the wave-transparent layer, Z 0 is the equivalent impedance of air, and Z in is the input impedance of the integral structure of the absorption-transmission integrated frequency selective surface. The reflection coefficient is（1),
Wherein,As can be seen from the formula (1), Z in is determined by the physical structure of the material itself and the incident electromagnetic wave, and Z in=Z0 is required for f=0, i.e. no reflection in an ideal state, but identity is almost impossible, and an absorption-transmission integrated frequency selection surface needs to be designed reasonably to realize impedance matching.
Meanwhile, if it is desired to achieve transmission, the loss layer and the wave-transmitting layer are required to be almost transparent in the transmission band, and the transmission amount between the two ends can be calculated by the following formula: (2) As shown in the formula (2), when the impedance Z R resonates to infinity, the loss layer can realize signal transmission in a specific frequency band, but Z R easily resonates at a certain point and hardly realizes wireless resonance in a wide frequency band.
Referring to fig. 3 in combination, according to the embodiment of the invention, a first metal layer 1, a first dielectric substrate 2, a dielectric layer 3, a second metal layer 4, a second dielectric substrate 5, a third metal layer 6, a third dielectric substrate 7 and a fourth metal layer 8 are sequentially arranged from top to bottom, and the above eight structures jointly form a low-absorption high-transmission radome frequency selective surface. Wherein, the metal layer 1 is a topological coding structure with central symmetry, and the material is metallic copper (the conductivity is 5.8X10 7S/m2); the material of the dielectric substrate 2 is F4B (the relative dielectric constant is 2.65, the loss tangent is 0.002), and the optimized thickness is 0.58mm; the material of the middle dielectric layer 3 is Air (relative dielectric constant is 1.00059, magnetic conductivity is 1), and the optimized thickness is 6.84mm; the metal layer 4 and the metal layer 8 are of patch type structures, the material is PEC (ideal electric conductor), and the diameter of the PEC is 10.7mm; the metal layer 6 is of an aperture type structure, the material of the metal layer is PEC (ideal electric conductor), and the diameter of the aperture is 8.3mm; the materials of the dielectric substrate 5 and the dielectric substrate 7 were Rogers RO 4350B (relative dielectric constant: 3.66, loss tangent: 0.0037), and the thickness of each layer was 2mm. The period of the whole structure is 15mm (in the simulation of the invention, the thickness of the metal patch is set to be 0mm, the normal processing thickness is set to be 0.03mm, and the effects of the metal patch and the normal processing thickness in the simulation are not greatly different).
Referring to fig. 4 in combination, which shows the coding strategy of the first metal layer 1, the size of the coding matrix is 16×16, where 1 and 0 respectively represent the presence or absence of a metal patch. The invention divides the topological structure of the metal patch into 48 x 8 sub-blocks which are symmetrical with each other in center through the central line of the square boundary, and each sub-block is also symmetrical along the diagonal line. This design allows the entire topology to be represented efficiently by only encoding the symmetric parts of the sub-blocks and the diagonal lines. The method not only ensures the polarization insensitivity of the whole structure and the richness of the surface structure, but also reduces the difficulty of calculation and design.
Referring to fig. 5, the graph shows the return loss and insertion loss curves of the integral structure of the example at 0-10 ghz when the electromagnetic wave of TE polarization mode is perpendicularly incident, and it can be seen that the absolute value of s21 in the broadband range of 5.76-7.78 ghz is smaller than 3dB, and the minimum in-band insertion loss is only 1.15dB; and the absolute value S11 is larger than 10dB in the broadband range of 2.4-6.01 GHz and 6.53-6.92 GHz, and the highest return loss of the absorption band is 38.7dB.
Referring to fig. 6, the graph shows that the integral structure of the example has a wave transmittance and an absorption rate curve of 0-10 GHz when electromagnetic waves of a TE polarization mode are perpendicularly incident, and the wave transmittance is higher than 50% in a broadband range of 5.76-7.78 GHz, and can reach up to 77% at 7.06GHz, so that the integral structure has good broadband wave transmittance performance; the absorption rate is more than 90% in the broadband range of 2.58-4.18 GHz, more than 80% in the broadband range of 2.14-4.9 GHz, and the wave absorption rate can reach up to 95% at 3.27GHz, so that the low-frequency wave absorption performance is good. As can be seen from simulation data, the invention perfectly meets the design requirements, and meanwhile, has a certain performance and efficiency improvement.
The foregoing description of the preferred embodiments of the application is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the application. The foregoing is merely a preferred embodiment of the present application, and it should be noted that it will be apparent to those skilled in the art that modifications and variations can be made without departing from the technical principles of the present application, and these modifications and variations should also be regarded as the scope of the application.
Claims (5)
1. The low-absorption high-permeability radome frequency selective surface based on topological coding is characterized in that the frequency selective surface unit structure is a first metal layer, a first medium substrate, a medium layer, a second medium substrate, a third metal layer, a third medium substrate and a fourth metal layer from top to bottom, each layer is of a square structure with the same side length, the layers are closely attached to each other to form a cuboid structure with a square cross section, and TE polarization and TM polarization of the antenna have the same S parameter curve, namely the antenna has polarization insensitive electromagnetic characteristics;
The first metal layer is printed on the front surface of the first dielectric substrate, is in a topological coding configuration, divides the square surface into 16 multiplied by 16 subareas, each subarea is a small square patch area, is filled with metal patches with the same size and shape in the small square patch area, is filled with metal patches without the small square patch area in the 0 mode, and is a first metal layer;
the metal array is divided into 4 square areas with central symmetry by the central line of the square surface, each square area is divided into 2 triangular sub-blocks with diagonal symmetry by the diagonal line of the square surface, so that the square surface has mathematical configurations with central symmetry and diagonal symmetry; each square area comprises 8×8 small square patch areas, and the coding matrix representing the distribution condition of the metal patches in each square area is as follows:
this coding matrix also characterizes all metal patch distributions of the first metal layer, due to the central symmetry of the square surface.
2. The low-absorption high-transmission radome frequency selective surface based on topological coding according to claim 1, wherein the second metal layer and the fourth metal layer are respectively printed on the front surface of the second dielectric substrate and the central area of the back surface of the third dielectric substrate, and are metal round patches with the same diameter, and the diameters of the second metal layer and the fourth metal layer are smaller than the side length of a square boundary.
3. The low-absorption high-transmission radome frequency selective surface of claim 2, wherein the second dielectric substrate and the third dielectric substrate have the same thickness, but are different from the first dielectric substrate.
4. The low-absorption high-transmission radome frequency selective surface based on topological coding according to claim 1, wherein the third metal layer is printed on the back surface of the second dielectric substrate and the central area of the front surface of the third dielectric substrate, and is an aperture type metal patch structure with circular aperture, and the diameter of the aperture type metal patch structure is smaller than that of the circular patch of the second metal layer.
5. The low-absorption high-transmission radome frequency selective surface based on topological coding according to claim 1, wherein the thickness of the dielectric layer is larger than that of the dielectric substrate, and the dielectric layer is made of special materials to ensure the overall physical strength and electromagnetic performance.
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| CN110265780A (en) * | 2019-06-20 | 2019-09-20 | 南京航空航天大学 | A kind of Stealthy reflector Antenna cover of intermediate frequency broadband wave transparent, high and low frequency polarization conversion |
| CN220439893U (en) * | 2023-07-07 | 2024-02-02 | 中国人民解放军空军工程大学 | Transmission and scattering integrated frequency selective surface |
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| CN115313054A (en) * | 2022-08-10 | 2022-11-08 | 航天特种材料及工艺技术研究所 | Low-frequency wave-absorbing high-frequency wave-transmitting metamaterial structure |
| CN117559141B (en) * | 2023-11-01 | 2024-06-25 | 广东技术师范大学 | Transparent broadband metamaterial wave absorber based on topological optimization and preparation method thereof |
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| CN110265780A (en) * | 2019-06-20 | 2019-09-20 | 南京航空航天大学 | A kind of Stealthy reflector Antenna cover of intermediate frequency broadband wave transparent, high and low frequency polarization conversion |
| CN220439893U (en) * | 2023-07-07 | 2024-02-02 | 中国人民解放军空军工程大学 | Transmission and scattering integrated frequency selective surface |
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