Frequency selective surface structure and assembling method thereof

Abstract

The invention relates to the technical field of communication, and discloses a frequency selective surface structure and an assembling method thereof.The frequency selective surface structure comprises a plurality of layers of dielectric substrates, and a periodic metal pattern with the preset thickness is printed on the single-side surface of each layer of dielectric substrate; the pattern comprises a composite structure internally composed of a hexagonal grid and a square patch, and through holes and positioning pin holes formed in the outer edge; and the interlayer fixing structure comprises a gasket, a positioning pin and a fastener, the gasket is used for maintaining the air dielectric layer between the adjacent dielectric substrates, the positioning pin is used for being inserted into the positioning pin hole to align the substrate assembly, and the fastener is used for fixing the multiple layers of dielectric substrates by being inserted into the through hole. Good broadband transmission characteristics and angle stability are realized through a composite structure formed by the hexagonal grids and the square patches, air is used as an interlayer medium, the absorption loss of a medium material to electromagnetic waves is reduced, and the production efficiency is improved due to the characteristics of good performance and easiness in processing and assembling.

Description

Technical Field

[0001] The present invention relates to the field of communication technologies, and particularly relates to a frequency selective surface structure and an assembly method thereof. Background Art

[0002] In the new generation of microwave and millimeter-wave receiving technologies, multi-band simultaneous receiving systems have become a research hotspot. The multi-band simultaneous receiving technology can significantly improve the observation efficiency of radio telescopes and reduce the instrument cost, and is an important development direction of modern radio astronomy instrument technologies. The K / Q / W three-band cryogenic receiver integrates the feed horns of the K / Q / W three bands into a dewar, making the structure more compact. This requires designing a unique optical path in the microwave quasi-optical system of the receiver, so that the electromagnetic waves of the K / Q / W three bands can achieve effective isolation and simultaneous reception effects through transmission and reflection.

[0003] The dichroic filter used in the microwave quasi-optical system of a radio telescope receiver is designed based on the frequency selective surface (FSS) technology. A dichroic filter is a device that can selectively transmit or reflect signals of different bands according to the frequency of electromagnetic waves. Among them, FSS is an electromagnetic wave processing technology used to achieve this frequency selection function. It is composed of a specific periodically arranged metal structure. When electromagnetic waves irradiate the FSS at different incident angles and different polarization modes, a frequency-selective filtering phenomenon will occur.

[0004] The FSS technology is mainly divided into all-metal frequency selective surfaces and metal-dielectric frequency selective surfaces, where:

[0005] 1. The all-metal FSS structure has the following technical defects:

[0006] Sensitive to oblique incident angles and relatively narrow bandwidth. The all-metal FSS shows high angle sensitivity when facing oblique incident waves. Specifically, as the incident angle increases, an angle degradation phenomenon will occur, resulting in a sharp narrowing of the passband bandwidth and making it difficult to maintain a stable frequency response, thus limiting its practical application range in environments with large incident angles.

[0007] 2. The metal-dielectric FSS structure has the following technical defects:

[0008] High insertion loss. In the design process of broadening the passband bandwidth of the metal-dielectric FSS structure, it is necessary to increase the number of dielectric layers and the intermediate bonding layer, thereby introducing a high insertion loss. This loss stems from the energy attenuation of electromagnetic waves during transmission in multi-layer dielectric materials, resulting in a decrease in the overall transmission efficiency and making it difficult to meet the requirements of low loss and high-efficiency transmission. Summary of the Invention

[0009] Therefore, the present invention provides a frequency selective surface structure and an assembly method thereof, which overcome the technical problems of high angular sensitivity, limited bandwidth, and large insertion loss existing in the frequency selective surface structure in the prior art.

[0010] To solve the above technical problems, in a first aspect, an embodiment of the present invention provides a frequency selective surface structure, including: a multi-layer dielectric substrate and an interlayer fixing structure, wherein:

[0011] On one side surface of each layer of the multi-layer dielectric substrate, a periodic metal pattern with a preset thickness is printed. The periodic metal pattern includes: a composite structure composed of a hexagonal grid and a square patch inside, and through holes and positioning pin holes arranged at the outer edge;

[0012] The interlayer fixing structure includes gaskets, positioning pins, and fasteners. The gaskets are used to maintain the air dielectric layer between adjacent dielectric substrates. The positioning pins are used to insert into the positioning pin holes for substrate assembly alignment. The fasteners are used to fix the multi-layer dielectric substrate by inserting through the through holes.

[0013] The frequency selective surface structure provided by the embodiment of the present invention is composed of a composite structure of a hexagonal grid and a square patch. The combination of the hexagonal grid and the square patch can more effectively regulate signals such as electromagnetic waves. By precisely regulating the layer spacing and metal pattern parameters, frequency selectivity in the K / Q / W three bands, good broadband transmission characteristics, and angular stability are achieved. The through holes and positioning pin holes arranged at the outer edge facilitate interlayer fixing and the installation of the substrate assembly. The through holes are used to insert fasteners to realize the fixed connection of the multi-layer dielectric substrate, ensuring the mechanical strength and stability of the overall structure; the positioning pin holes cooperate with the positioning pins to accurately align the substrate assembly, ensuring the accurate relative position between layers, which is beneficial to improving the performance and reliability of the product; using air as the interlayer medium to replace the traditional adhesive medium reduces the raw material cost while reducing the absorption loss of the dielectric material to electromagnetic waves.

[0014] In an embodiment, the frequency selective surface structure further includes: an outer frame assembly, including a rigid frame with a preset thickness and a groove with a preset inner side length, for wrapping the multi-layer dielectric substrate. The material composition and inner side length of the outer frame assembly are the same as those of the gasket, but the thickness is different.

[0015] The embodiment of the present invention further enhances the stability of the entire FSS structure through the outer frame assembly. The outer frame is a rigid frame, which can wrap the multi-layer dielectric substrate, protect the internal structure from the influence of the external environment, and prevent the structure from deforming due to external forces, thereby ensuring the long-term stability of the FSS structure performance.

[0016] In one embodiment, the multi-layer dielectric substrate includes upper, middle, and lower dielectric substrates, and each dielectric substrate uses Rogers 5880 material; and / or, the dielectric constant is 2.2; and / or, the loss tangent is 0.0009.

[0017] The multi-layer dielectric substrate of the embodiment of the present invention uses Rogers 5880 material. Compared with common dielectric substrates such as Rogers 4350 and polyimide, it has a lower loss tangent, can significantly reduce the energy loss of signals during transmission, is more suitable for developing frequency selective surfaces with low insertion loss, ensures the high efficiency of signal transmission, and is especially suitable for communication systems with high requirements for signal quality.

[0018] In one embodiment, the periodic metal pattern includes graphic units that are periodic in the horizontal and vertical directions to form the composite structure.

[0019] The graphic units of the embodiment of the present invention are regularly arranged periodically in the horizontal and vertical directions, so that the electromagnetic characteristics of the FSS structure have high repeatability and stability. Different shapes of graphic units are periodically combined to generate electromagnetic resonance and other effects in different frequency intervals respectively. The periodic arrangement in the horizontal and vertical directions enables the electromagnetic effects in these different frequency intervals to be superimposed and coordinated with each other, greatly broadening the frequency range that the FSS structure can select and process.

[0020] In one embodiment, the key dimensional parameters of the graphic unit include: the unit width is 1.50 - 1.70 mm; and / or, the unit length is 2.60 - 2.94 mm; and / or, the line width is 0.05 - 0.10 mm; and / or, the side length of the patch is 0.40 - 0.60 mm; and / or, the side length of the hexagon is 0.80 - 1.00 mm.

[0021] The reasonable setting of the dimensional parameters in the embodiment of the present invention helps to improve the stability of the FSS structure at different incident angles of electromagnetic waves. When electromagnetic waves are obliquely incident on the FSS structure at an angle of 0 - 30°, a suitable dimensional design can enable the graphic unit to maintain good frequency selection characteristics for electromagnetic waves within the incident angle range of 0 - 30°, and reduce the performance fluctuations caused by the change of the incident angle.

[0022] In one embodiment, the preset layer spacing between adjacent dielectric substrates is 0.60 - 1.20 mm; and / or, the thickness of the metal pattern is 0.018 mm; and / or, the thickness of the dielectric substrate is 0.127 mm; the side length of the dielectric substrate is 80 mm; and / or, the preset inner side length of the outer frame and the gasket is 68 mm; and / or, the diameter of the through hole is 3.2 mm; and / or, the diameter of the positioning pin hole is 1.6 mm.

[0023] In the embodiments of the present invention, by setting an appropriate layer spacing, the metal patterns of each layer can generate a synergistic electromagnetic response at a specific frequency, thereby optimizing the frequency selection characteristics of the FSS structure and achieving efficient transmission or reflection of electromagnetic waves in a specific frequency band; an appropriate thickness can enable the metal pattern to achieve the best balance between the reflection and transmission characteristics of electromagnetic waves, improve the overall electromagnetic performance of the FSS structure, and reasonable layer spacing and the setting of each part size enable the FSS structure to maintain a relatively stable frequency response when electromagnetic waves are incident within the range of 0 - 30°, enhancing its adaptability in a complex electromagnetic environment.

[0024] In a second aspect, the embodiments of the present invention provide an assembly method for a frequency selective surface structure, which is used to prepare and assemble the frequency selective surface structure described in the first aspect, including:

[0025] Preparing periodic metal patterns on a dielectric substrate by lithography;

[0026] Alternately stacking and aligning multiple dielectric substrates and spacers through positioning pin holes;

[0027] Performing pre-assembly using positioning pins with a matching coefficient of thermal expansion, and applying fasteners in stages for fastening to form a multi-layer dielectric substrate structure.

[0028] In the embodiments of the present invention, high-precision pattern transfer is achieved through lithography, and periodic metal patterns with specific sizes and shapes can be accurately prepared, ensuring the accuracy and consistency of the metal patterns, which helps to achieve the precise frequency selection characteristics and good electromagnetic performance of the frequency selective surface structure; the alternate stacking method helps to ensure the uniformity of the entire structure in the plane, enabling electromagnetic waves to have similar electromagnetic characteristics at different positions when propagating in the structure, reducing performance fluctuations and non-uniformities;

[0029] The positioning pins are used for aligning the substrate components, which can ensure the accurate alignment of multiple dielectric substrates and spacers during the stacking process, guaranteeing the assembly accuracy of the entire structure; applying fasteners in stages for fastening helps to gradually adjust and optimize the tightness of the structure during the assembly process, avoiding local stress concentration or component misalignment that may be caused by one-time fastening, and improving the mechanical strength and reliability of the structure.

[0030] In one embodiment, the method further includes: installing an outer frame assembly on the multi-layer dielectric substrate structure, and applying uniform pressure to the structure after installing the outer frame assembly to eliminate assembly stress.

[0031] The outer frame component can provide stable mechanical support for the multi-layer dielectric substrate structure. It can serve as an integral mounting frame, facilitating the installation of the frequency selective surface structure into other devices or systems. At the same time, it also helps to accurately position the structure during installation, ensuring the relative position accuracy with other components and facilitating the good integration of the entire system. During the assembly process of the multi-layer dielectric substrate structure, due to the connection and stacking between components, assembly stress will inevitably be generated. In the embodiments of the present invention, by applying uniform pressure, these assembly stresses can be released and evenly distributed, reducing stress concentration inside the structure, thereby improving the stability and reliability of the structure.

[0032] In one embodiment, the method further includes: performing passband insertion loss testing and angle stability testing.

[0033] In the embodiments of the present invention, by measuring the insertion loss within the passband frequency range, the energy loss of the signal during the transmission process through this structure can be accurately quantified. The energy transmission efficiency of the structure within the passband can be clarified, and it can be determined whether it meets the design requirements, providing a key basis for evaluating the signal transmission quality of the structure in practical applications. By changing the incident angle of the electromagnetic wave and measuring the transmission and reflection characteristic parameters of the structure within the incident angle range of 0 - 30°, the performance of the structure under different incident angles can be comprehensively understood. Evaluate whether it can stably maintain the frequency selection function in the face of incoming waves from different directions in a complex electromagnetic environment, and accurately judge the pros and cons of the angle stability of the structure.

[0034] In one embodiment, the method further includes: establishing a database to record the test data for performance comparison and evaluation of different batches or improved frequency selective surface structures.

[0035] In the embodiments of the present invention, by storing the test data of different batches of frequency selective surface structures in the database, the performance of each batch of products can be compared horizontally. The performance differences between different batches can be quickly discovered, which helps to control the quality stability of the products and promptly discover the factors that may affect the product performance during the production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0037] Figure 1 Schematic diagram of the metal pattern of the single-layer dielectric substrate in the embodiments of the present invention;

[0038] Figure 2It is a perspective schematic diagram of the frequency selective surface structure in the embodiment of the present invention;

[0039] Figure 3 It is an assembly schematic diagram of the frequency selective surface structure in the embodiment of the present invention;

[0040] Figure 4 It is a schematic diagram of the graphic unit in the embodiment of the present invention;

[0041] Figure 5 It is a flowchart of the assembly method of the frequency selective surface structure in the embodiment of the present invention;

[0042] Figure 6 In the embodiment, the simulation result of the S parameter of TE polarization when the frequency selective surface is obliquely incident at 30°;

[0043] Figure 7 In the embodiment of the present invention, the simulation result of the S parameter of TM polarization when the frequency selective surface is obliquely incident at 30°.

[0044] Reference numerals:

[0045] 1 - Square patch; 2 - Hexagonal grid; 3 - Through hole; 4 - Locating pin hole; 5 - Outer frame assembly. Detailed implementation manners

[0046] In order to better understand the above technical solutions, exemplary embodiments will be described in detail herein, and the examples are shown in the drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementation manners described in the following exemplary embodiments do not represent all implementation manners consistent with the present application. On the contrary, they are merely examples of devices consistent with some aspects of the present application as detailed in the appended claims.

[0047] Embodiment 1

[0048] This embodiment provides a frequency selective surface structure, including: a multi-layer dielectric substrate and an interlayer fixing structure, wherein:

[0049] On one side surface of each layer of the multi-layer dielectric substrate, a periodic metal pattern with a preset thickness is printed. The periodic metal pattern includes: a composite structure composed of a hexagonal grid and a square patch inside, and through holes and locating pin holes arranged at the outer edge;

[0050] The interlayer fixing structure includes gaskets, locating pins and fasteners. The gaskets are used to maintain the air dielectric layer between adjacent dielectric substrates. The locating pins are used to insert into the locating pin holes for substrate assembly alignment, and the fasteners are used to fix the multi-layer dielectric substrate by inserting into the through holes.

[0051] Specifically, the schematic diagram of the metal pattern of the single-layer dielectric substrate with side length S in the embodiments of the present invention is as follows Figure 1 As shown, the square patch 1 is located at the center of the hexagonal grid 2. The two cooperate to reflect or transmit electromagnetic waves in a specific frequency band, expanding the working frequency band width of the FSS structure and realizing the frequency selection function for a wider frequency band. By precisely controlling the layer spacing and metal pattern parameters, the frequency selectivity in the K / Q / W three bands and good broadband transmission characteristics are achieved. Aiming at the influence of the oblique incidence angle on the FSS performance, through the optimized geometric structure and arrangement of the metal pattern, it can maintain stable frequency selectivity, low loss characteristics and angle stability.

[0052] As Figure 1 shown, a plurality of through holes 3 with diameter D1 and positioning pin holes 4 with diameter D2 are provided on the outer edge, which facilitates the interlayer fixation and the installation of the substrate assembly. The positioning pin holes 4 cooperate with the positioning pins to accurately align the substrate assembly, ensuring that each dielectric substrate printed with a metal pattern can be accurately aligned, improving the accuracy of the multi-layer dielectric substrate stacking, ensuring the consistency of the spatial positions of the metal patterns on each layer, and further ensuring the stability of the frequency selection performance of the FSS structure; the mechanical strength of the entire FSS structure is enhanced through the stable connection method of the through holes 3 and the fixing parts, preventing the structure from loosening due to factors such as vibration and external force impact during use, which affects the electromagnetic performance. In the embodiments of the present invention, the entire structure is positioned and fixed by using positioning pins and fasteners (such as M3 screws), avoiding the performance degradation caused by deformation.

[0053] As Figure 2 shown is the perspective schematic diagram of the frequency selective surface structure. Taking the upper, middle and lower three-layer dielectric substrates and the layer spacing d as an example, the gasket thickness in the embodiments of the present invention determines the layer spacing of the dielectric substrates. Using air as the interlayer medium to replace the traditional adhesive medium reduces the raw material cost and at the same time reduces the absorption loss of electromagnetic waves by the dielectric material. Due to its good performance and easy processing and assembly characteristics, the scrap rate can be reduced during the production process, the production efficiency is improved, and the manufacturing cost is further reduced.

[0054] In the embodiments of the present invention, each dielectric substrate adopts Rogers 5880 material, with a dielectric constant of 2.2 and a loss tangent of 0.0009, and the thickness of a single substrate is 0.127 mm. Compared with the commonly used Rogers4350 and polyimide and other dielectric substrates, the Rogers 5880 dielectric substrate has a lower loss tangent, can significantly reduce the energy loss of signals during transmission, is more suitable for developing frequency selective surfaces with low insertion loss, ensuring the high efficiency of signal transmission, and is especially suitable for communication systems with high requirements for signal quality.

[0055] In one embodiment, the frequency selective surface structure provided by the embodiments of the present invention further includes: an outer frame assembly, including a rigid frame with a preset thickness and a slot on the inner side with a preset length, for wrapping the multi-layer dielectric substrate. The outer frame assembly has the same material composition and structure as the gasket, but different thicknesses. In one embodiment, the thickness of the outer frame assembly is 3 mm, the thickness of the gasket is equal to the spacing d, which is 0.60 - 1.20 mm, and there is a slot with a side length of S1 inside. The assembly schematic diagram of the three-layer dielectric substrate structure with the outer frame assembly is as shown in Figure 3 shown. The stability of the entire FSS structure is further enhanced by the outer frame assembly 5. The outer frame is a rigid frame, which can wrap the multi-layer dielectric substrate, protect the internal structure from the external environment, and prevent the structure from deforming due to external forces, thus ensuring the mechanical stability of the FSS structure and the feasibility of repeated manufacturing.

[0056] Under air dielectric conditions, the embodiments of the present invention fix the three-layer dielectric substrate through the outer frame and the gasket, achieving high flexural rigidity. Under the action of force or changes in the external environment, the deformation of the plate structure is still small, and it can maintain stable strength and performance. In addition, even if the layer spacing changes due to the deformation of the dielectric substrate, the passband loss can still be as low as 0.21 dB within a certain range, which is significantly better than the traditional design.

[0057] Furthermore, the periodic metal pattern is printed on one side surface of the dielectric substrate in the embodiments of the present invention and is composed of copper material with a thickness of 0.018 mm. The periodic metal pattern includes graphic units that are periodic in the horizontal and vertical directions (as shown in Figure 4 shown) to form a composite structure. The key dimensional parameters involved in the graphic units and other structural components are shown in Table 1.

[0058] Table 1 Dimensional Parameter Table

[0059]

[0060]

[0061] The embodiments of the present invention determine the electromagnetic resonance characteristics of the graphic units by designing these dimensional parameters. For example, a specific numerical combination of the unit width, length, and the side lengths of the hexagon and the patch enables the graphic units to resonate within a specific frequency range. This resonance characteristic enables the FSS structure to selectively transmit or reflect electromagnetic waves in a specific frequency band, thereby achieving an accurate frequency selection function. In a communication system, it can accurately filter out signals in the required frequency band, effectively suppress signals in other interference frequency bands, and improve communication quality.

[0062] In addition, precise dimensional parameters help ensure the electromagnetic performance stability of the graphic units. When the external environmental conditions change, appropriate dimensional design can reduce the change in the electromagnetic characteristics of the graphic units, thereby reducing the frequency shift of the FSS structure. This enables the FSS structure to maintain stable frequency selection performance under different environmental conditions and improves the reliability of the system. The reasonable setting of the dimensional parameters also helps improve the stability of the FSS structure under different incident angles of electromagnetic waves. When electromagnetic waves are obliquely incident on the FSS structure at an angle of 0 - 30°, appropriate dimensional design can enable the graphic units to maintain good frequency selection characteristics for electromagnetic waves within the incident angle range of 0 - 30°, reducing the performance fluctuations caused by the change in the incident angle.

[0063] The frequency selective surface structure provided by the embodiments of the present invention can be applied to the scenario of the microwave quasi-optical system of a K / Q / W triple-band refrigeration receiver. The dichroic filter of the embodiments of the present invention can selectively transmit electromagnetic wave signals in the W band (80 - 110 GHz) and reflect electromagnetic wave signals in the K band (18 - 26 GHz) and the Q band (35 - 50 GHz). The subsequent dichroic filter selectively transmits the electromagnetic wave signals in the Q band and reflects the electromagnetic wave signals in the K band according to the reflected electromagnetic wave signals in the K band and the Q band, thereby realizing the simultaneous reception of the K / Q / W three bands.

[0064] Embodiment 2

[0065] The embodiments of the present invention provide an assembly method for a frequency selective surface structure, which is used to prepare the frequency selective surface structure in Embodiment 1, such as Figure 5 , including:

[0066] S1: Prepare periodic metal patterns on the dielectric substrate by photolithography.

[0067] Through the photolithography process, the embodiments of the present invention can achieve high-precision pattern transfer, accurately prepare periodic metal patterns with specific dimensions and shapes, ensure the accuracy and consistency of the metal patterns, and help achieve the precise frequency selection characteristics and good electromagnetic performance of the frequency selective surface structure.

[0068] S2: Stack and align multiple dielectric substrates and spacers alternately through positioning pin holes.

[0069] In the embodiment of the present invention, the distance between adjacent dielectric substrates can be precisely controlled through gaskets, ensuring that the preset layer spacing is accurately achieved. Precise layer spacing is crucial for optimizing the electromagnetic performance of the frequency selective surface structure. It can control the electromagnetic coupling between layers, thereby achieving effective transmission or reflection of electromagnetic waves at specific frequencies. The alternating stacking method helps to ensure the uniformity of the entire structure in the plane, enabling the electromagnetic waves to have similar electromagnetic characteristics at different positions when propagating in the structure, reducing performance fluctuations and non-uniformities.

[0070] S3: Perform pre-assembly using positioning pins with a matched coefficient of thermal expansion, and apply fasteners in stages for fastening to form a multi-layer dielectric substrate structure.

[0071] In the embodiment of the present invention, positioning pins with a matched coefficient of thermal expansion can avoid thermal stress caused by different degrees of thermal expansion of the positioning pins, dielectric substrates, gaskets and other components under different temperature conditions. Thermal stress may cause structural deformation, damage, or change the size and position of the metal pattern, thereby affecting the performance of the frequency selective surface structure. Using positioning pins with a matched coefficient of thermal expansion helps to improve the stability and reliability of the structure in different temperature environments. Applying fasteners in stages for fastening helps to gradually adjust and optimize the tightness of the structure during the assembly process, avoiding local stress concentration or component misalignment that may be caused by one-time fastening, and improving the mechanical strength and reliability of the structure.

[0072] S4: Install the outer frame assembly on the multi-layer dielectric substrate structure, and apply uniform pressure to the structure after installing the outer frame assembly to eliminate assembly stress.

[0073] Specifically, the outer frame assembly can provide stable mechanical support for the multi-layer dielectric substrate structure, making it not easily deformed or damaged when subjected to external force impact or vibration, protecting the internal dielectric substrates, metal patterns and other structures from damage, and ensuring the performance stability of the frequency selective surface structure. The outer frame assembly can serve as an overall installation frame, facilitating the installation of the frequency selective surface structure into other devices or systems. At the same time, it also helps to accurately position the structure during the installation process, ensuring the relative position accuracy with other components, which is beneficial to achieving good integration of the entire system.

[0074] During the assembly process of the multi-layer dielectric substrate structure, due to the connection and stacking of various components, assembly stress will inevitably be generated. These stresses may cause slight deformation or displacement of the structure during use, affecting its performance stability. In the embodiment of the present invention, by applying uniform pressure, these assembly stresses can be released and evenly distributed, reducing stress concentration inside the structure, thereby improving the stability and reliability of the structure.

[0075] S5: Conduct passband insertion loss testing and angular stability testing.

[0076] Specifically, for the passband insertion loss test: By measuring the insertion loss within the passband frequency range under a specific electromagnetic environment, the energy loss of the signal during transmission through this structure can be accurately quantified. The energy transmission efficiency of the structure within the passband is clarified, whether it meets the design requirements is judged, providing a key basis for evaluating the signal transmission quality of the structure in practical applications.

[0077] Angle stability test: In a shielded environment, the incident angle of the electromagnetic wave is changed, and the transmission and reflection characteristic parameters of the structure within the incident angle range of 0 - 30° are measured to comprehensively understand the performance of the structure under different incident angles. Evaluate whether it can stably maintain the frequency selection function in the face of waves coming from different directions in a complex electromagnetic environment, and accurately judge the pros and cons of the angle stability of the structure.

[0078] Based on the electromagnetic field simulation software, the above frequency selective surface structure is simulated within the incident angle range of 0 - 30° in the embodiments of the present invention. Figure 6 And Figure 7 According to the shown simulation results, a set of typical values within the parameter range in Table 1 is used for modeling and simulation. The specific parameters are: P1 = 1.60 mm, P2 = 2.77 mm, W = 0.08 mm, hl = 0.50 mm, L = 0.90 mm, d = 0.90 mm. This set of parameters takes values in the middle of the set range and is representative, capable of reflecting the typical transmission characteristics of the structure within this parameter range. The specific results are as follows:

[0079] As Figure 6 Shown is the simulation result of the S - parameter of TE polarization when the frequency selective surface is obliquely incident at 30°. Within the frequency band range of the K - band and Q - band (18 - 50 GHz), the reflection loss S11 obtained by simulating this frequency selective surface is within 0.20 dB; within the frequency band range of the W - band (80 - 110 GHz), the simulated insertion loss is less than 0.20 dB.

[0080] As Figure 7 Shown is the simulation result of the S - parameter of TM polarization when the frequency selective surface is obliquely incident at 30°. Within the frequency band range of the K - band and Q - band (18 - 50 GHz), the reflection loss S11 obtained by simulating this frequency selective surface is within 0.35 dB; within the frequency band range of the W - band (80 - 110 GHz), the simulated insertion loss is less than 0.21 dB. The simulation results of TE and TM polarizations show excellent angle stability and wide - band characteristics.

[0081] From the above simulations, it can be seen that the frequency selective surface structure provided by the embodiments of the present invention achieves a stable wide operating bandwidth under wide incident angle conditions. In the microwave quasi-optical system of a K / Q / W triple-frequency refrigeration receiver, for the 30° oblique incidence condition, a relative bandwidth of 31.6% with a 0.2 dB is achieved, and excellent passband flatness is exhibited in the range of 80 - 110 GHz.

[0082] S6: Establish a database to record the test data for performance comparison and evaluation of different batches or improved frequency selective surface structures.

[0083] Specifically, the embodiments of the present invention store the test data of frequency selective surface structures of different batches in the database, enabling horizontal comparison of the performance of each batch of products. It can quickly identify performance differences between different batches, such as whether the passband insertion loss is stable within a specific range and the fluctuation of the angle stability parameter. This helps to control the product quality stability and promptly discover factors that may affect product performance during the production process, such as process fluctuations and raw material differences. For performance shortboards found during testing, such as the passband insertion loss exceeding the threshold or the angle stability not meeting the standard, detailed data in the database can be used for analysis. By studying the relationship between structural parameters such as metal pattern size, layer spacing, and dielectric substrate material and performance, the root cause of the problem can be accurately located, guiding the direction for optimizing and improving the structure.

[0084] It should be understood that although terms such as "first" and "second" may be used here to describe various units, these units should not be limited by these terms. These terms are only used to distinguish one unit from another. For example, without departing from the scope of the exemplary embodiments, the first unit may be referred to as the second unit, and similarly, the second unit may be referred to as the first unit.

[0085] The orientation terms such as up, down, left, right, front, back, front side, back side, top, and bottom mentioned or possibly mentioned in this specification are defined relative to the structures shown in the respective drawings. They are relative concepts and may therefore change accordingly depending on their different positions and usage states. Therefore, these or other orientation terms should not be construed as restrictive terms.

[0086] In the description of the present application, it should be noted that unless otherwise clearly specified and defined, the terms "mounted", "connected", and "connected" should be understood in a broad sense. For example, it may be a fixed connection, or an indirect connection through an intermediate medium, or the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0087] In addition, the terms "comprising", "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or apparatus that comprises a series of steps or units need not be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or apparatuses.

[0088] As described above, the above are only the preferred embodiments of the present application and do not impose any formal or substantial limitations on the present application. It should be noted that for those of ordinary skill in the art of this technology, without departing from the method of the present application, several improvements and supplements can still be made, and these improvements and supplements should also be regarded as within the protection scope of the present application. For those skilled in the art, any equivalent changes, such as minor modifications, decorations and evolutions made without departing from the spirit and scope of the present application by using the technical content disclosed above, are equivalent embodiments of the present application; at the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present application still fall within the scope of the technical solution of the present application.

Claims

1. A frequency selective surface structure, characterized in that, It includes a multi-layer dielectric substrate and an interlayer fixing structure, where: On one side surface of each layer of the multi-layer dielectric substrate, a periodic metal pattern with a preset thickness is printed. The periodic metal pattern includes: a composite structure composed of a hexagonal grid and a square patch inside, and through holes and positioning pin holes arranged on the outer edge; The interlayer fixing structure includes gaskets, positioning pins and fasteners. The gaskets are used to maintain the air dielectric layer between adjacent dielectric substrates. The positioning pins are used to insert into the positioning pin holes for alignment of the substrate components. The fasteners are used to fix the multi-layer dielectric substrate by inserting through the through holes.

2. The frequency-selective surface structure according to claim 1, wherein The frequency selective surface structure further includes: An outer frame assembly, including a rigid frame with a preset thickness and a slot on the inner side with a preset length, for wrapping the multi-layer dielectric substrate; the outer frame assembly has the same material composition and structure as the gaskets, but different thicknesses.

3. The frequency-selective surface structure according to claim 1 or 2, characterized in that, The multi-layer dielectric substrate includes upper, middle and lower layers of dielectric substrates, and each layer of dielectric substrate uses Rogers 5880 material; and / or, The dielectric constant is 2.2; and / or, The loss tangent is 0.0009.

4. The frequency-selective surface structure according to claim 1, wherein The periodic metal pattern includes graphic units that are periodic in the horizontal and vertical directions to form the composite structure.

5. The frequency-selective surface structure according to claim 4, characterized in that, The key dimensional parameters of the graphic units include: The unit width is 1.50 - 1.70 mm; and / or, The unit length is 2.60 - 2.94 mm; and / or, The line width is 0.05 - 0.10 mm; and / or, The side length of the patch is 0.40 - 0.60 mm; and / or, The side length of the hexagon is 0.80 - 1.00 mm.

6. The frequency-selective surface structure according to claim 5, characterized in that, The preset layer spacing between adjacent dielectric substrates is 0.60 - 1.20 mm; and / or, The thickness of the metal pattern is 0.018 mm; and / or, The thickness of the dielectric substrate is 0.127 mm; and / or, The side length of the dielectric substrate is 80 mm; and / or, The preset inner side length of the outer frame and the gasket is 68 mm; and / or, The diameter of the through hole is 3.2 mm; and / or, The diameter of the positioning pin hole is 1.6 mm.

7. A method for assembling a frequency selective surface structure, for preparing the assembled frequency selective surface structure according to any one of claims 1-6, characterized in that, It includes: Preparing a periodic metal pattern on the dielectric substrate by photolithography; Stacking and aligning the multi-layer dielectric substrate and the gaskets alternately through the positioning pin holes; Performing pre-assembly using positioning pins with a matching coefficient of thermal expansion, and applying fasteners in stages for fastening to form a multi-layer dielectric substrate structure.

8. The assembly method of the frequency-selective surface structure according to claim 7, characterized in that, It further includes: Installing an outer frame assembly on the multi-layer dielectric substrate structure, and applying uniform pressure to the structure after installing the outer frame assembly to eliminate assembly stress.

9. The assembling method of the frequency-selective surface structure according to claim 7 or 8, characterized in that, It further includes: Performing passband insertion loss testing and angle stability testing.

10. The assembling method of the frequency-selective surface structure according to claim 9, characterized in that, It further includes: Establishing a database to record the test data for performance comparison and evaluation of different batches or improved frequency selective surface structures.

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