Frequency selective surface design method for realizing performance superposition through patch combination

Abstract

The invention belongs to the field of electromagnetic wave-absorbing frequency selective surface design, and particularly relates to a frequency selective surface design method for realizing performance superposition through patch combination, which comprises the following steps: establishing a corresponding FSS basic unit model by using simulation software according to design requirements; the method comprises the following steps of: acquiring a wave-absorbing performance index, establishing a wave-absorbing performance database corresponding to different FSS basic units, performing parameter sweep frequency analysis, decomposing the performance index into a regional performance index according to a wave-absorbing performance requirement, and screening FSS patches meeting the regional performance index from the wave-absorbing performance database; combining the screened FSS patches to obtain a frequency selective surface scheme meeting performance requirements; the designed FSS scheme is prepared by using a surface processing means, the data volume in a database is accumulated and increased in the use process, more samples for screening are provided for subsequent design, the optimal solution under the performance target can be obtained under any condition, the combination mode in the combination process is optimized, and the design efficiency is improved. And the problem of polarization sensitivity is avoided.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of electromagnetic wave absorbing frequency selective surface design. Specifically, it is a frequency selective surface design method for realizing performance superposition through patch combination. The design method combines simple patches to realize the superposition of the advantages of simple patches and obtain a wideband, high-polarization-stable electromagnetic wave absorbing design scheme. BACKGROUND

[0002] At present, wave-absorbing materials have been widely used in the field of aerospace, especially in the aspect of equipment, and the requirements for wave-absorbing performance are higher. However, due to the structure design of wave-absorbing materials and the dielectric and magnetic properties of the materials themselves, the wave-absorbing materials only have good wave-absorbing performance in a specific frequency band, and there is a problem of narrow wave-absorbing bandwidth. In addition, the thickness of the wave-absorbing material directly affects its wave-absorbing performance. Generally, thicker materials can provide better wave-absorbing effect, because the increase in thickness can improve the multiple reflection and absorption of electromagnetic waves by the material. However, too thick wave-absorbing materials not only increase the weight, but also may adversely affect the mechanical properties of the substrate, especially in the field of aerospace and other fields with extremely high requirements for weight and structure.

[0003] Frequency selective surface (FSS) is a periodic array structure composed of a large number of passive resonant units, which can be metal patches or apertures arranged periodically on metal patches. By adjusting the unit shape, size, dimension, and period of such periodic structure material, the transmission and reflection characteristics of electromagnetic waves can be effectively controlled, significantly expanding the research and application range of wave-absorbing materials.

[0004] CN118970474A discloses a frequency selective surface with the coupling effect of multiple metal patches, forming multiple

[0005] resonant cavities, each of which produces multiple modes of electromagnetic resonance due to different frequencies of electromagnetic waves, thereby improving the absorption performance of electromagnetic waves and realizing high absorption and thin thickness of the super surface, but its application frequency band is limited to the S band; China CN118920111A proposes a wideband wave-absorbing frequency selective surface and a design method thereof. The frequency selective surface obtained by the design method is a single-layer structure, and the surface FSS is a solid patch type unit shape, but it limits the shape, arrangement size parameters, etc. of the FSS unit, which is not conducive to wide range of applications.

[0006]

[0007] SUMMARY

[0008] ​​To solve the above problems in the prior art, a wide-band, multi-shape and freely combined wide-band frequency selective surface unit combination design method is provided.The frequency selective surface designed by the method can be compatible with the excellent performance of each basic unit, widen the absorption bandwidth, and is simple and convenient to design, thereby greatly reducing the time cost of traversal screening calculation under different design requirements.

[0009] The complete technical solution of the application comprises:

[0010] A frequency selective surface design method for achieving performance superposition through patch combination, according to design requirements, a plurality of FSS basic unit models are established by using simulation software;

[0011] A set of wave absorption performance data corresponding to the plurality of FSS basic units is established;

[0012] For the target performance of the frequency selective surface, the target performance is decomposed into regional performance indicators according to the absorption peak distribution position of the wave absorption curve in the wave absorption performance database;

[0013] FSS basic units meeting the regional performance indicators are screened in the wave absorption performance database;

[0014] The screened FSS basic units are combined to obtain a frequency selective surface design scheme.

[0015] Further, the establishment of the set of wave absorption performance data corresponding to the plurality of FSS basic units comprises: determining the periodic size of the plurality of shape FSS basic units that meet the preset requirements of wave absorption intensity and wave absorption bandwidth; setting the size of the plurality of FSS basic units under the periodic size, and performing parameter sweep analysis to obtain wave absorption performance; the set of wave absorption performance data established comprises the shape, size and corresponding wave absorption performance of the FSS basic unit.

[0016] Further, the establishment of the set of wave absorption performance data corresponding to the plurality of FSS basic units comprises setting the same feature size, simulating the models of different shape FSS basic units under different periodic sizes, and screening out the periodic sizes that meet the preset requirements of intensity and wave absorption bandwidth according to the output wave absorption performance intensity and bandwidth.

[0017] Further, the target performance comprises one or more of the following: wave absorption bandwidth, wave band, wave absorption intensity under each wave band, and average wave absorption intensity under all wave bands.

[0018] Further, in the screening of FSS basic units meeting the regional performance indicators in the wave absorption performance database, the FSS basic unit screening is based on one or more of the following: wave absorption bandwidth, wave absorption intensity, and the number of feature sizes of the FSS basic unit.

[0019] Further, under the premise that the wave absorption bandwidth and the wave absorption intensity meet the requirements, the FSS basic unit with the least number of characteristic dimensions is selected.

[0020] Further, the combination of the screened FSS basic units to obtain the frequency selective surface design scheme comprises: the screened FSS basic units are arranged in a central symmetry, and the arrangement mode with the smallest overall period size is selected.

[0021] Further, the size of the FSS basic unit is not changed during the arrangement.

[0022] Further, the frequency selective surface design scheme after the arrangement of the FSS basic units is simulated and analyzed to obtain a reflection loss performance curve, the coincidence degree of the wave absorption performance of the frequency selective surface design scheme and the target performance is calculated, and whether the design requirements are met is determined according to the coincidence degree.

[0023] Further, a frequency selective surface is obtained by using any one of the frequency selective surface design methods and by a surface processing method.

[0024] Further, the surface processing scheme used includes but is not limited to magnetron sputtering, screen printing and surface laser processing and other surface processing means known to those skilled in the art.

[0025] The advantages of the present application over the prior art are:

[0026] (1) The existence of the wave absorption performance database can increase the accumulation of data in the database during use, provide more samples for subsequent design, and save the calculation time cost of repeated modeling.

[0027] (2) The performance segmentation and screening according to the database content can obtain the optimal solution under the performance target in any case, which improves the design feasibility compared with the pre-segmentation and setting of the performance target and then the searching for the corresponding FSS patch performance.

[0028] (3) Compared with the prior art, the combination mode in the combination process is greatly optimized, the selection of the central symmetry combination mode avoids the occurrence of polarization sensitivity problems, and the small period size after the combination ensures the performance stability of the FSS design scheme when applied to small-sized workpieces.

[0029] (4) The use of a mask in the magnetron sputtering and screen printing processes can conveniently prepare a complex FSS surface shape, and will not increase the process complexity. The use of laser processing can prepare a complex pattern shape on a smaller-sized workpiece surface, and the process is simple and the machining precision is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a flow chart of the design method of the present invention.

[0031] Figure 2 It is an example diagram of the FSS model of the design method of the present invention.

[0032] Figure 3 This is a partial data diagram in the database involved in Examples 1 and 2 of the design method of the present invention.

[0033] Figure 4 This is a schematic diagram of a combination mode used in Example 1 of the design method of the present invention.

[0034] Figure 5 This is a reflection loss performance diagram after combining Example 1 of the design method of the present invention.

[0035] Figure 6 It is a combination pattern diagram adopted in Example 2 of the design method of the present invention.

[0036] Figure 7 This is a reflection loss performance diagram after combining Example 2 of the design method of the present invention.

[0037] Figure 8 This is a partial data diagram in the database involved in Example 3 of the design method of the present invention.

[0038] Figure 9 It is a combination pattern diagram adopted in Example 3 of the design method of the present invention.

[0039] Figure 10 This is a reflection loss performance diagram after combining Example 3 of the design method of the present invention. DETAILED DESCRIPTION

[0040] The present invention is described in detail below with reference to the embodiments and accompanying drawings. However, it should be understood that the embodiments and accompanying drawings are merely exemplary descriptions of the present invention and do not constitute any limitation on the scope of protection of the present invention. All reasonable variations and combinations within the scope of the inventive concept of the present invention fall within the scope of protection of the present invention.

[0041] According to an embodiment of the present invention, Figure 1 As shown, the present invention provides a design method for a broadband absorbing frequency selective surface, comprising the following steps:

[0042] Step (1): Model the FSS model according to actual needs. Figure 2 shown.

[0043] Step (2): Size optimization of the model to determine the appropriate period size, specifically: for the strength of the wave absorption performance and bandwidth requirements, first set the same feature size, using different shape FSS patch (i.e. FSS basic unit) in different period size model for simulation, according to the output of the wave absorption performance strength and bandwidth are selected out the highest intensity, the largest wave absorption bandwidth period size.

[0044] In this period size set different FSS patch shape and size and parameter sweep analysis to establish a database, in which the sweep step is set according to the actual needs, specifically according to the time cost, calculation amount and FSS size in the process to determine, if the sweep frequency of the time is short, can be set to sweep frequency step larger, if there is no time requirement or requirement for high calculation accuracy, can be set to sweep frequency step smaller, to output a plurality of data for enriching the database volume, in the above process need to consider the size of the FSS patch itself, such as for mm level patch size, sweep frequency step can be set to 0.01mm, 0.05m, 0.1mm, 0.5mm, etc., if the patch itself size is μm level, the sweep frequency step should also be reduced accordingly, not strictly set here. After sweep, all the results are summarized to form a database; performance data example summary as shown in Figure 3 .

[0045] Step (3): According to the distribution of wave absorption performance in the database, the target performance is matched and decomposed.

[0046] Among them, the target performance (i.e. wave absorption performance) includes the bandwidth of wave absorption, wave band, wave absorption intensity under each wave band, and average wave absorption intensity under all wave bands, etc. The wave absorption intensity under each wave band is expressed by reflection loss, specifically: i <R Li , where f i is the i-th wave band, R Li is the reflection loss of the i-th wave band. The average wave absorption intensity is specifically:

[0047] The target performance decomposition step is decomposed according to the distribution position of the absorption peak of the wave absorption curve in the database, such as the absorption peak is roughly divided into X wave band, Ku wave band, X and Ku junction three categories, then the target performance decomposition is also divided into X, Ku, X and Ku junction three segments, if the absorption peak distribution position changes, the corresponding decomposition form will also change.

[0048] Step (4): According to the target performance decomposition results, the corresponding FSS patch is selected from the database. The selection basis is: Under the premise of ensuring the target bandwidth, the FSS patch with higher absorption strength is selected. However, if the bandwidth is ≤ 0.2 GHz and the absorption strength is < -10 dB, the FSS patch also meets the requirements, and the FSS patch with a simpler shape is selected from the FSS patches that meet the requirements.

[0049] In this paper, the simplicity of FSS patches is characterized by the number of characteristic dimensions. For example, a circle has only one radius and is the simplest shape. A square has one side and is the next simplest shape. A rectangle has two sides and has two characteristic dimensions, making it more complex than a square. This is analogous to more complex patterns such as hexagonal snowflakes. Therefore, patch shapes with fewer characteristic dimensions are preferred during screening.

[0050] Step (5): The screened FSS patches are combined and arranged according to the principle of central symmetry, requiring the overall period size after combination to be as small as possible while not changing the size of the original FSS patch itself.

[0051] Step (6): Simulate and analyze the performance of the combined FSS patch to obtain the final reflection loss performance curve, determine the absorbing performance of the broadband absorbing frequency selective surface obtained by the above frequency selective surface method, and its consistency with the set indicators, and whether it can achieve a satisfactory design effect.

[0052] In the present invention, the degree of coincidence is characterized by the absorption bandwidth and intensity, and the degree of coincidence δ is defined as:

[0053] δ=∑(f j / f i )

[0054] f j It is in the band f i Within, meet the absorption strength requirements ( <RL i Preferably, in the present invention, δ≥95% is considered to be a good match.

[0055] The corresponding steps (1) to (3) Figure 2 and Figure 3 After optimization of the model and performance data shown in FIG, a broadband frequency selective absorbing surface is obtained, such as Figure 4 As shown, it includes: multiple FSS units arranged in a periodic manner, each FSS unit contains multiple metal patches of different shapes and sizes, and each FSS unit also includes a dielectric plate, on which a combination of FSS patches of different shapes and sizes is arranged according to the principle of central symmetry. Adjacent metal patches are arranged closely according to their period, and the patch spacing can be fixed or not.

[0056] To further verify the beneficial effects of the frequency selective surface (FSS) designed by the design method of the broadband wave-absorbing frequency selective surface of the application, the following examples are provided for further illustration.

[0057] Example 1

[0058] A FSS structure unit with broadband wave-absorbing performance is prepared, and the performance requirements are as follows: the wave-absorbing frequency band is 9-17 GHz, the bandwidth is 8 GHz, and the target wave-absorbing resonance performance is that the wave-absorbing intensity S11 is -5 dB.

[0059] Step (1): In order to obtain the broadband wave-absorbing performance of the wave-absorbing coating, four simple patches are modeled under a period size of 5 mm x 5 mm, as shown in Figure 2 .

[0060] Step (2): The FSS model is optimized, the frequency scanning step is set to 0.05 mm, and all the results are summarized to obtain a database containing the above four patch shapes, and part of the data is shown as follows Figure 3 .

[0061] Step (3): According to the performance target 9-17 GHz <-5 dB and the performance distribution in the database, the target performance is divided into three sections: 8-11 GHz <-5 dB, 11-14 GHz <-5 dB and 14-18 GHz <-5 dB, and the database data meeting the conditions in the above three sections are selected to obtain the optimal results of different patch reflection loss absorption peaks located in the target section.

[0062] Step (4): Among the data in the database, the r=0.80 mm circular patch with the highest absorption intensity in the range of 11-14 GHz and the 2.00 mm x 1.50 mm cross-shaped patch with the highest absorption intensity in the ranges of 8-11 GHz and 14-18 GHz are selected for combination.

[0063] Step (5): According to the principle of central symmetry, the selected patches are combined in a 4:5 ratio. Since it is necessary to ensure that the period size after combination is as small as possible, a central diffuse distribution mode of circular patches and cross-shaped patches is selected, as shown in Figure 4 .

[0064] Step (6): The reflection loss curve obtained after the combination design retains the reflection loss absorption peaks in the three frequency bands of 8-11 GHz, 11-14 GHz and 14-18 GHz, as shown in Figure 5 , the overall absorption bandwidth is greatly improved, achieving a broadband absorption of 8.57-17.08 GHz with a reflection loss performance of <-5 dB, a total of 8.51 GHz.

[0065] The above is described in detail taking the wave-absorbing frequency band as (9-17) GHz and the bandwidth as 8 GHz. For any target wave-absorbing frequency band, the wave-absorbing performance of the wideband wave-absorbing frequency selection surface obtained by the design method of the application is highly consistent with the set index, and a satisfactory design effect can be achieved. That is, the wideband wave-absorbing frequency selection surface designed by the method of the application has the advantages of continuous wideband wave-absorbing, simple design, and repeated accumulation of database use, and the designed wideband wave-absorbing frequency selection surface is more central symmetric than the prior art, has higher stability of incident angle, and has better cross-polarization suppression capability.

[0066] Example 2

[0067] A FSS structure unit with wideband absorbing performance is prepared, and the performance requirements are as follows: the wave-absorbing frequency band is Ku band (12-18 GHz), the wave-absorbing intensity is less than -10 dB in the range of 12-16.5 GHz, the wave-absorbing intensity is less than -5 dB in the range of 16.5-18 GHz, and the average wave-absorbing intensity in the frequency band is less than -12.5 dB.

[0068] Step (1): consistent with example 1, in order to obtain the wideband absorbing performance of the wave-absorbing coating, four simple patches are modeled under a period size of 5 mm x 5 mm, as shown in Figure 2 .

[0069] Step (2): the FSS model is optimized, the frequency scanning step is set to 0.05 mm, and all the results are summarized to obtain a database containing the above four patch shapes, part of the database is as shown in Figure 3 .

[0070] Step (3): according to the performance target 12-16.5 GHz <-10 dB, 16.5-18 GHz <-5 dB and the performance distribution in the database, the target performance is divided into 12-13.5 GHz <-10 dB, 13.5-15 GHz <-10 dB, 15-16.5 GHz <-10 dB and 16.5-18 GHz <-5 dB, and the data in the database that meet the conditions in the above four segments are screened to obtain the optimal results of different patch reflection loss absorption peaks located in the target segment.

[0071] Step (4): the 1.25 mm x 1.25 mm square patch with the highest absorption intensity in the range of 12-13.5 GHz, the 0.25 mm x 0.25 mm square patch with the highest absorption intensity in the range of 13.5-15 GHz, and the 4.50 mm x 0.50 mm cross-shaped patch with the highest absorption intensity in the range of 15-16.5 GHz and the absorption intensity less than -5 dB in the range of 16.5-18 GHz are selected from the database for combination.

[0072] Step (5): According to the principle of central symmetry, the patches obtained by screening are combined in a ratio of 1:4:4. Since it is necessary to ensure that the periodic size after combination is small, a large and small square patch and a cross-shaped patch are selected for central dispersive distribution mode, as shown in Figure 6 .

[0073] Step (6): As shown in Figure 7 , the reflection loss curve obtained after combination design and superposition retains the reflection loss absorption peaks in the 12-13.5 GHz, 13.5-15 GHz, 15-16.5 GHz, and 16.5-18 GHz frequency bands. The overall absorption bandwidth is greatly improved, achieving the above-mentioned Ku-band wide frequency absorption performance index.

[0074] Example 3

[0075] A FSS structure unit with wide frequency absorption performance needs to be prepared, and the performance specific requirements are: under the required thickness index (not more than 1 mm), the absorption frequency band is X band (8-12 GHz), the full-band absorption performance is <-5 dB, and the average absorption intensity is <-8 dB.

[0076] Step (1): In order to control the absorption performance to X band, we set the coating thickness to 0.8 mm according to the needs when modeling. We model 4 simple patches under a periodic size of 5 mm x 5 mm, as shown in Figure 2 .

[0077] Step (2): Optimize the structure of the above FSS model, set the frequency sweep step to 0.05 mm, and collect all the results to obtain a database containing the above four patch shapes. Part of the database is shown in Figure 8 .

[0078] Step (3): According to the performance target 8-12 GHz <-5 dB and the performance distribution in the database, the target performance is divided into 8-10 GHz <-5 dB and 10-12 GHz <-5 dB. The data in the database that meets the conditions in the above two sections is screened to obtain the optimal results of different patch reflection loss absorption peaks located in the target section.

[0079] Step (4): Among the data in the database, the 1.50 mm x 2.60 mm strip patch with the highest absorption intensity in the 10-12 GHz range and the 2.60 mm x 1.50 mm strip patch, and the 1.00 mm x 0.50 mm cross patch with the highest absorption intensity in the 10-12 GHz range are selected for combination.

[0080] Step (5): According to the principle of central symmetry, the patches obtained by screening are combined in a ratio of 2:2:5. Since the periodic size after combination needs to be as small as possible, two kinds of strip patches and cross-shaped patch central dispersive distribution mode are selected, as shown in Figure 9 .

[0081] Step (6): As shown in Figure 10 , the reflection loss curve obtained by superimposing the combined design retains the reflection loss absorption peaks in the 8-10 GHz and 10-12 GHz frequency bands, and the overall absorption bandwidth is greatly improved, meeting the design requirements.

[0082] The above application is only some embodiments of the application. Those skilled in the art can make several modifications and improvements without departing from the inventive concept of the application, and these all belong to the protection scope of the application.

Claims

1. A method for designing a frequency selective surface that achieves performance superposition through patch combination, characterized in that: Based on design requirements, various FSS basic unit models are established using simulation software; Establishing a radar absorption performance data set corresponding to the multiple FSS basic units; For the target performance of the frequency selective surface, the target performance is decomposed into regional performance indicators according to the absorption peak distribution position of the absorption curve in the absorption performance database; Screening the FSS basic units that meet the regional performance indicators in the radar absorption performance database; The screened FSS basic units are combined to obtain the frequency selective surface design scheme.

2. A method for designing a frequency selective surface that achieves performance superposition through patch combination according to claim 1, characterized in that: The establishing of the absorption performance data sets corresponding to the various FSS basic units includes: determining a periodic size at which the various shapes of the FSS basic units all meet preset requirements for absorption intensity and absorption bandwidth; setting the sizes of the various FSS basic units under the periodic size, and performing a parameter sweep analysis to obtain absorption performance; the established absorption performance data set includes the shapes, sizes, and corresponding absorption performance of the FSS basic units.

3. The method for designing a frequency selective surface that achieves performance superposition through patch combination according to claim 1, characterized in that: The establishment of the absorption performance data set corresponding to the multiple FSS basic units includes setting the same characteristic size, using models of FSS basic units of different shapes at different period sizes for simulation, and screening out period sizes whose intensity and absorption bandwidth meet preset requirements based on the output absorption performance intensity and bandwidth.

4. The method for designing a frequency selective surface that achieves performance superposition through patch combination according to claim 1, characterized in that: The target performance includes one or more of the bandwidth, waveband, absorption intensity in each waveband and average absorption intensity in all wavebands of the wave absorption.

5. The method for designing a frequency selective surface that achieves performance superposition through patch combination according to claim 1, characterized in that: In the screening of the FSS basic units that meet the regional performance index in the wave absorption performance database, the FSS basic units are screened based on one or more of the wave absorption bandwidth, the wave absorption intensity, and the number of characteristic dimensions of the FSS basic units.

6. The method for designing a frequency selective surface that achieves performance superposition through patch combination according to claim 5, characterized in that: On the premise that the absorption bandwidth and absorption intensity meet the requirements, the FSS basic unit with the least number of characteristic dimensions is selected.

7. The method for designing a frequency selective surface that achieves performance superposition through patch combination according to claim 1, characterized in that: The method of combining the screened FSS basic units to obtain a frequency selective surface design includes arranging the screened FSS basic units in a centrally symmetrical manner and selecting a combination arrangement with the smallest overall period size.

8. The method for designing a frequency selective surface that achieves performance superposition through patch combination according to claim 7, characterized in that: During the combination and arrangement process, the size of the FSS basic unit itself does not change.

9. The method for designing a frequency selective surface for achieving performance superposition through patch combination according to claim 8, characterized in that: The frequency selective surface design scheme after the combination and arrangement of FSS basic units is simulated and analyzed to obtain the reflection loss performance curve. The degree of consistency between the frequency selective surface design scheme's absorption performance and the target performance is calculated, and whether it meets the design requirements is judged based on the degree of consistency.

10. A frequency selective surface, characterized in that The frequency selective surface is a frequency selective surface design scheme obtained by using any one of the frequency selective surface design methods in claims 1-9, and is prepared by a surface processing method.

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