A design method and system of a stable performance conical surface tunable frequency selective surface

Abstract

The application belongs to the technical field of electromagnetic materials, and provides a design method and system of a conical surface tunable frequency selective surface with stable performance. According to the performance evolution law of the FSS under the conical surface conformal transformation, the FSS period shape and arrangement mode are determined. Whether the geometric parameter value of the optimized conical surface tunable frequency selective surface structure meets the set target IL value is judged. If the geometric parameter value of the optimized conical surface tunable frequency selective surface structure does not meet the set target IL value, the geometric parameter value of the conical surface tunable frequency selective surface structure is redesigned according to the insertion loss improvement strategy. The proposed curved surface TFSS design process has low IL, high conformality and wide angle domain stability.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic materials technology, and in particular relates to a method and system for designing a stable, tunable, frequency-selective conical surface. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Aircraft radomes are typically streamlined structures and must possess sufficient strength and thermal insulation to protect radar antennas and ensure their proper functioning under harsh operating conditions. High-performance aircraft radomes often also require bandpass characteristics (high transmittance within the operating frequency band and weak reflection outside the operating frequency band). This ensures normal communication with friendly radar within the band while simultaneously reflecting enemy detection electromagnetic waves to non-primary detection directions outside the band, reducing the echo intensity and achieving electromagnetic stealth.

[0004] Adding an electromagnetic functional layer to an aircraft radome is an effective way to achieve high wave transmission within the operating frequency band and weak reflection outside the operating frequency band. The radome wall structure mainly consists of an electromagnetic functional layer and a dielectric layer. The electromagnetic functional layer is essentially a frequency selective surface (FSS), which is a periodic microstructure array composed of metal units. It can achieve spatial filtering of electromagnetic waves of different frequencies, polarizations, and incident angles. Generally, it can be divided into low-pass, high-pass, band-stop, and band-pass FSS structures, while those added to aircraft radomes are usually band-pass FSS structures. With the increasing complexity of the external electromagnetic environment and the increasing maturity of internal radar antenna communication functions, band-pass FSS structures with multiple transmission passbands, wide transmission passbands, and wide-angle domain stability are constantly emerging. However, once the aircraft radome with such an electromagnetic functional layer is manufactured, its bandpass characteristics cannot be adjusted in real time.

[0005] To achieve wide-spectrum stealth performance for aircraft radomes and enhance their penetration capabilities, a new type of aircraft radome equipped with an active electromagnetic functional layer has emerged. The active electromagnetic functional layer is essentially an active frequency selective surface (AFSS), composed of a microstructure array of load-parameter-controllable elements, which require external excitation sources for adjustment. Compared to PIN diodes, AFSSs equipped with varactor diodes are better suited to the complex and ever-changing operational environment of modern warfare. Regardless of whether the radar is on or off, the radome's operating frequency can be adjusted online in real time by regulating the varactor diodes, achieving wide-spectrum stealth design. Simultaneously, it can also meet the frequency-following requirements of modern multi-band, wide-bandwidth, and frequency-converting radar antenna systems. This tunable AFSS can be further termed a tunable frequency selective surface.

[0006] To achieve the high-performance characteristics of an aircraft radome—"in-band active control of wave transmission and out-of-band broadband electromagnetic stealth"—a bandpass-type TFSS structure needs to be loaded onto the radome. However, current research on bandpass-type TFSS structures is limited to planar structures. Considering that in practical applications, the outer profile of high-performance aircraft radomes is often a high-order non-developable surface, if the planar TFSS structure is pieced together and composited onto the non-developable outer profile using transfer screen technology, it will disrupt the unit period and feed network of the TFSS structure, leading to the failure of the active control function in the transmission passband. If the non-developable TFSS structure is designed directly, it is constrained by the difficulty in solving the electromagnetic model of large-size, multi-scale non-developable TFSS structures, the low efficiency of iterative optimization, and the difficulty in finding the optimal solution. Under current mainstream hardware resources, it is not possible to directly perform simulation optimization design of non-developable TFSS structures. The design basis of the non-developable TFSS structure is the developable TFSS structure. If the planar TFSS structure that meets the target response is directly conformally transformed to the developable surface, the corresponding transmission performance will be distorted.

[0007] To achieve the design of a non-developable TFSS structure with high transmission stability, the following three major challenges still need to be addressed: 1. Study on the performance evolution of FSS under conformal transformation. Since the TFSS structure is developed by adding varactor diodes and feeding network on the basis of the FSS structure, considering that the planar TFSS structure needs to load a large number of varactor diodes and the metal pattern is generally more complex, the computational mesh after conformal transformation is more numerous, making it difficult to conduct a large number of numerical simulation analyses to obtain the influence of microstructure shape changes and arrangement on wave transmission performance under conformal transformation.

[0008] 2. Design of a planar TFSS structure with wide-angle domain stability. High-performance aircraft radomes are generally streamlined structures with a large range of incident angles θʹ in different regions. To load a TFSS structure onto a high-performance aircraft radome and achieve the performance of "in-band active control of wave transmission and out-of-band broadband electromagnetic stealth," the loaded TFSS structure needs to be designed for planar wide-angle domain stability under conformal transmission performance constraints to ensure that the curved TFSS structure after conformal transformation has good transmission performance and stability. Simultaneously, considering the adverse effects of conformal transformation on wide-angle domain stability, the planar TFSS structure needs to have stable transmission performance within a large incident angle range (typically 0-70°). However, current wide-angle domain stability designs for planar TFSS structures are mostly limited to 45° or 60°, which is insufficient to meet the requirements for wide-angle domain stability of planar TFSS structures under conformal constraints. Since the planar TFSS structure is the design basis for the curved TFSS structure... Summary of the Invention

[0009] To overcome the shortcomings of the prior art, the present invention provides a stable method and system for designing a conical tunable frequency selective surface, which has low IL, high conformal performance and wide-angle domain stability.

[0010] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for designing a stable, tapered, tunable frequency-selective surface, comprising: Based on the performance evolution law of FSS under conical conformal transformation, the periodic shape and arrangement of FSS are determined; Set the target IL value and design a cone-shaped tunable frequency selection surface structure based on the insertion loss improvement strategy; Determine whether the optimized cone-shaped tunable frequency selection surface structure meets the set target IL value; If the optimized cone-shaped tunable frequency selection surface structure meets the set target IL value, then the process ends; If the optimized conical tunable frequency selection surface structure does not meet the set target IL value, then the geometric parameter values ​​of the conical tunable frequency selection surface structure should be re-optimized.

[0011] Furthermore, the top bandpass structure of the designed conical tunable frequency selective surface unit has a hexagonal periodic shape and is arranged in a triangular pattern.

[0012] Furthermore, the top bandpass structure of the cone-shaped tunable frequency selective surface element was determined through simulation, specifically as follows: Simulation of the transmission coefficients of conical FSS structures with different half-angles β under polarized waves in the y and x directions when the incident wave is along the positive z-axis; Simulation of the transmission coefficients of conical FSS structures with different half-angles β under polarized waves in the y and x directions when the incident wave is along the negative z-axis. Based on the simulation results, the half-angle β of the conical FSS structure with good conformal stability when electromagnetic waves are incident along both the negative and positive z-axis directions was determined, and the top bandpass structure with high conformal stability was determined.

[0013] Furthermore, the simulation calculation process for the transmission coefficient is as follows: Calculate the far-field reflection coefficient of a finite large frequency selective structure in the transmission direction; Calculate the total field in the transmission direction of the air layer with the same dimensions as the finite large frequency selective structure; The transmission coefficient of the finite large frequency selective structure can be obtained by subtracting the total field of the air layer with the same size as the finite large frequency selective structure in the transmission direction from the far-field reflection coefficient of the finite large frequency selective structure obtained by simulation in the transmission direction.

[0014] Furthermore, after determining the top bandpass structure with high conformal stability, the bottom feed structure is designed. Considering the size of the varactor diode, a strip is added inside the outer hexagonal ring of the top bandpass structure. The bottom feed structure consists of three strips with overlapping centers and an outer hexagonal ring, resulting in the initial conical TFSS unit structure.

[0015] Furthermore, based on the initial conical TFSS unit structure, a unit zigzag method is adopted to increase the miniaturization of the underlying power supply structure.

[0016] Furthermore, based on the initial conical TFSS unit structure and considering conformal stability constraints, the curved strip inside the top bandpass structure is changed to a patch, and the bottom feed structure strip is bent in the first order. The material and thickness of the dielectric substrate and the position of the loaded varactor diode remain unchanged, resulting in a conical tunable frequency-selective surface unit structure.

[0017] Furthermore, the designed conical tunable frequency selection surface structure has a hexagonal shape and consists of a top bandpass structure, a dielectric substrate, metal vias, and a bottom feed structure. The top bandpass structure consists of an outer hexagonal ring and an inner deformed hexagonal patch; the center positions of the outer hexagonal ring and the inner deformed hexagonal patch are the same; the bottom feed structure consists of an outer hexagonal ring and an inner bent metal patch; the inner bent metal patch is composed of a metal strip with a first-order bend; the center positions of the bottom hexagonal ring and the bottom inner bent metal patch are the same.

[0018] Furthermore, the varactor diode is placed in the gap formed by the outer hexagonal ring of the top layer and the deformed hexagonal patch inside the top layer; the anode of the varactor diode is connected to the outer hexagonal ring of the top layer, and the cathode of the varactor diode is connected to the center of the bottom layer bent metal strip with first-order bending through a metal through-hole located at the center position; multiple varactor diodes are connected in parallel.

[0019] Furthermore, an equivalent circuit model is established for the designed conical tunable frequency selection surface. The effectiveness of the established equivalent circuit model is verified by comparing the transmission coefficient calculated from the equivalent circuit model with the simulated transmission coefficient.

[0020] Furthermore, the first constraint for reducing the IL value of the curved TFSS structure is that the frequency point at which the impedance matching between the bottom-level feed structure and the top-level bandpass structure is achieved should not exceed the transmission pole of the top-level bandpass structure; the second constraint for reducing the IL value of the curved TFSS structure is to ensure that the top-level bandpass structure has a small IL value.

[0021] Secondly, the present invention provides a high-performance, tunable, frequency-selective surface design system for conical surfaces, comprising: The determination module is configured to: determine the periodic shape and arrangement of the FSS based on the performance evolution law of the FSS under the conical conformal transformation; The design module is configured to: set the target IL value and design a conical tunable frequency selection surface structure based on the insertion loss improvement strategy; The judgment module is configured to: determine whether the optimized conical tunable frequency selection surface structure meets the set target IL value; if the optimized conical tunable frequency selection surface structure meets the set target IL value, then end; if the optimized conical tunable frequency selection surface structure does not meet the set target IL value, then re-optimize the geometric parameter values ​​of the conical tunable frequency selection surface structure.

[0022] Thirdly, the present invention provides an electronic device including a memory and a processor, and computer instructions stored in the memory and running on the processor, wherein the computer instructions, when executed by the processor, perform the method described in the first aspect.

[0023] Fourthly, the present invention provides a computer-readable storage medium for storing computer instructions, which, when executed by a processor, perform the method described in the first aspect.

[0024] Fifthly, the present invention provides a computer program product, including a computer program that, when executed by a processor, implements the method described in the first aspect.

[0025] The above one or more technical solutions have the following beneficial effects: In this invention, based on the performance evolution law of FSS under conical conformal transformation, the periodic shape and arrangement of FSS are determined. It is then determined whether the geometric parameter values ​​of the optimized conical tunable frequency selective surface structure meet the set target IL value. If the optimized geometric parameter values ​​do not meet the target IL value, the geometric parameter values ​​of the conical tunable frequency selective surface structure are redesigned based on the insertion loss improvement strategy. The proposed surface TFSS design flow, which combines low IL, high conformality, and wide-angle domain stability, reduces the IL of the optimized TFSS by 60.7% compared to the initial TFSS, while satisfying the constraints of high conformality and wide-angle domain stability (≥60°). This provides a solution for designing surface TFSSs with the above characteristics, overcoming the design challenges of surface TFSSs.

[0026] In this invention, under the constraint of transmission performance, when the periodic shape of the FSS is hexagonal, a triangular arrangement is required, which provides theoretical and technical support for designing a curved surface TFSS with high conformal stability.

[0027] This invention proposes a simulation method for calculating the transmission performance of finite-size plane and finite-size curved surface frequency-selective structures. A Gaussian plane wave is used to simulate actual plane wave incidence, allowing for the simulation of the far-field values ​​in the transmission direction for both the finite-size frequency-selective structure and an air layer of the same size. Subtracting these two far-field values ​​yields the transmission coefficient of the finite-size frequency-selective structure. The simulation method proposed in this invention does not neglect the influence of edge diffraction effects on transmission performance, thus improving simulation accuracy.

[0028] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0029] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0030] Figure 1 This is a flowchart illustrating the design process of a conical TFSS structure with high transmission stability in an embodiment of the present invention. Figure 2 This is a schematic diagram of the top bandpass structure in an embodiment of the present invention; wherein, (a) is a 3D diagram, (b) is a front view, and (c) is a side view; Figure 3 The diagrams show the conical FSS structures with different half-angles and the corresponding planar sector FSS structures in the embodiments of the present invention; wherein, (a) is a schematic diagram of the planar sector FSS structure with different half-angles, and (b) is a schematic diagram of the conical FSS structure with different half-angles. Figure 4The transmission coefficient of the conical FSS structure in this embodiment of the invention is the incident wave direction along the positive z-axis; where (a) is the y-direction polarized wave and (b) is the x-direction polarized wave. Figure 5 Here, represents the transmission coefficient of the conical FSS structure in the embodiment of the present invention when the incident wave direction is along the negative z-axis; where (a) is the y-direction polarized wave and (b) is the x-direction polarized wave. Figure 6 This is a schematic diagram of the initial TFSS unit structure in an embodiment of the present invention; wherein, (a) is a 3D diagram, (b) is a front view, and (c) is a side view; Figure 7 The transmission coefficients of the initial TFSS structure under oblique incidence in this embodiment of the invention are: (a) TE polarized wave, (b) TM polarized wave. Figure 8 This is a schematic diagram of the final conical TFSS unit structure in an embodiment of the present invention; wherein, (a) is a 3D diagram, (b) is the top-level structure, and (c) is the bottom-level structure; Figure 9 The simulated transmission coefficients of the TFSS structure in a planar array are shown in the embodiments of the present invention. Figure 10 This is an ECM diagram of the TFSS structure in an embodiment of the present invention; Figure 11 This is a comparison chart of the transmission coefficients calculated by ECM and simulated by CST in an embodiment of the present invention; Figure 12 The transmission coefficient of the TFSS structure under oblique incidence in a planar array in the embodiment of the present invention is given by (a) C. 11= 0.55pF, TE polarization wave; (b) C 11 =0.55pF, TM polarized wave, (c) C 11 =0.21pF, TE polarized wave; (d) C 11 =0.21pF, TM polarized wave; Figure 13 These are planar and conical TFSS structure samples in the embodiments of the present invention; wherein, (a) is a planar TFSS structure sample; and (b) is a conical TFSS structure sample. Figure 14 The transmission coefficient of the conical TFSS structure sample under vertical incidence in the embodiment of the present invention is shown; where (a) is a TE polarized wave and (b) is a TM polarized wave. Figure 15 This represents the test transmission coefficient of the conical TFSS sample under oblique incidence in an embodiment of the present invention; wherein, (a) V 11 =6V, TE polarization wave; (b) V11 = 6V, TM polarized wave, (c) V 11 = 20V, TE polarized wave; (d) V 11 = 20V, TM polarized wave. Detailed Implementation

[0031] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0032] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations of the present invention.

[0033] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0034] Terminology Explanation: A Fast Spectrometer (FSS) is an infinitely periodic array composed of unit cells that can transmit or reflect electromagnetic waves within a certain frequency range. The unit cell structure mainly consists of a metal pattern and a dielectric substrate. The frequency response of an FSS is affected by factors such as the metal pattern, the dielectric layer, the arrangement of the unit cells, the polarization of the incident electromagnetic wave, and the incident angle.

[0035] Example 1 This embodiment addresses the design problem of non-developable TFSS structures, focusing on the design method of "flat-then-curved based on conformal technology" to achieve the design of non-developable TFSS structures with "in-band active control of wave transmission and out-of-band broadband electromagnetic stealth" characteristics. This provides a useful reference for improving the stealth technology and penetration capability of high-performance aircraft radomes.

[0036] like Figure 1 As shown, this embodiment provides a stable cone-shaped tunable frequency selective surface design method, the specific steps of which are as follows: Based on the performance evolution law of FSS under conical conformal transformation, the periodic shape and arrangement of FSS are determined; Set the target IL value and design a cone-shaped tunable frequency selection surface structure based on the insertion loss improvement strategy; Determine whether the optimized cone-shaped tunable frequency selection surface structure meets the set target IL value; If the optimized cone-shaped tunable frequency selection surface structure meets the set target IL value, then the process ends; If the optimized conical tunable frequency selection surface structure does not meet the set target IL value, then the geometric parameter values ​​of the conical tunable frequency selection surface structure should be re-optimized.

[0037] A conical surface can be equivalent to a combination of cylindrical surfaces with different bending radii. Therefore, FSS unit structures with high conformal stability can be screened under the conformal transformation of cylindrical surfaces and placed on a planar sector structure in a certain arrangement. Then, the influence of different arrangement methods on the transmission performance of the conical FSS structure can be explored, and the evolution law of FSS performance under the conformal transformation of conical surfaces can be revealed.

[0038] Based on the principle of the bow measurement method proposed by the U.S. Naval Research Laboratory, this embodiment proposes a simulation method for calculating the transmission performance of frequency-selective structures with finite large planes and finite large curved surfaces.

[0039] When a plane wave is incident on an infinitely large structure, the relationship between the total field, the incident field, and the scattered field in the transmission region of the structure satisfies: (1) in, For the main field, To remove the incident field of the test sample during air testing; This is the scattered field. Since an ideal metal plate has a transmission coefficient of 0 and a reflection coefficient of 1 when a plane wave is incident perpendicularly, we have: (2) in, , , Let represent the total field, incident field, and scattered field of the transmission region of an ideal metallic plate, respectively. When a plane wave is incident on an infinitely large dielectric plate or an infinitely large metallic plate, the reflection coefficient and transmission coefficient are calculated as follows: (3) in, These are the reflection coefficient and transmission coefficient of the dielectric substrate, respectively. These represent the scattered field and the total field of the transmission region of the dielectric plate, respectively. Based on this, the reflection coefficient of the infinitely large frequency-selective structure... It can be defined as: (4) in, This represents the scattering field of a frequency-selective structure.

[0040] When a plane wave is incident perpendicularly into an ideal air layer, its transmission coefficient is 1 and its reflection coefficient is 0. Therefore: (5) in, as well as These represent the total field, incident field, and scattered field of an ideal air layer in the transmission region, respectively. Based on this, the transmission coefficient of the infinitely large frequency-selective structure... It can be defined as: (6) in, The total field of the frequency-selective structure. Based on the above analysis, formulas (2) and (5) hold true when the metal plate is totally reflective and the air layer is totally transmissive, and formulas (4) and (6) hold true only when these conditions are met. and This is the incident field when there is no metal plate or air layer. .

[0041] The simulation calculation process for the transmission coefficient of a finite large frequency selective structure is as follows: a Gaussian plane wave is used to simulate the actual plane wave incidence, and the far field of the finite large frequency selective structure in the transmission direction is simulated and calculated. ; Calculate the far-field of the air layer with dimensions consistent with the finite large frequency selective structure in the transmission direction. The simulation results minus The transmission coefficient of a finite large frequency selective structure can be obtained.

[0042] The simulation calculation process for the reflection coefficient of a finite large frequency selective structure is as follows: a Gaussian plane wave is used to simulate the actual plane wave incident, and the far field of the finite large frequency selective structure in the scattering direction is calculated. ; Calculate the far-field of a metal plate with dimensions consistent with a finite large frequency selective structure in the scattering direction. The simulation results minus The reflection coefficient of a finite large frequency selective structure can be obtained.

[0043] For a conical tunable frequency selective surface (TFSS) structure, the periodic shape and arrangement of the FSS elements must first be determined. Based on this, in this embodiment, the periodic shape of the conical TFSS elements is hexagonal, and a fan-shaped arrangement is adopted. Under the constraints of high conformality and wide-angle domain stability, in order to achieve a conical TFSS element structure design with low IL, the top bandpass structure must have high conformal stability.

[0044] The first constraint for reducing the impedance IL value of a curved TFSS structure is the frequency at which the bottom-level feed structure and the top-level bandpass structure (TBS) achieve impedance matching. It should not exceed the transmission limit of TBS. The second constraint for reducing the IL value of the curved TFSS structure is that the TBS must have a small IL value.

[0045] Based on this, the pattern of the top bandpass structure is as follows: Figure 2As shown, the periodic shape is hexagonal, with hexagonal ring patches at the edges. The central pattern consists of bent hexagonal ring patches and six patches with first-order bends, with the centers of the bent hexagonal ring patches and the six patches with first-order bends coinciding. The dimensions of this top-layer structure pattern are: hexagonal periodic dimensions. p = 15mm; the dimensions of the central pattern are: g 1 = 2.96mm, g 2 = 1.34mm, l 1 = 2.0mm l 2 = 2.0mm l 3 = 4.275mm l 4 = 1.75mm s = 0.81mm; Width of the hexagonal ring at the edge d =2.7mm. The dielectric substrate of this structure has a thickness of... t The F4B-2 is 0.25mm thick.

[0046] To ensure high conformal stability of the conical FSS structure composed of hexagonal FSS units, a triangular arrangement is required. Figure 3 The diagram shows the arrangement of the top bandpass structure on a planar sector structure with different central angles δ, and the diagram of the resulting conical FSS structure with different half angles β.

[0047] To verify the transmission performance stability of the top-level bandpass structure under conical conformal transformation, simulations were performed with different half-angles. β The conical FSS structure along the incident wave z In the positive direction of the axis, y and x The transmission coefficient under directional polarization, such as Figure 4 As shown. Compared to the planar FSS structure, when the half-angle β When it reaches 30°, at y Under directional polarization, the resonant frequency shift rate | k f_c | 1.72%, -3dB bandwidth BW Reduced from 1.58 GHz to 0.921 GHz; x Under directional polarization waves, | k f_c | is 1.58%, BW The frequency decreased from 1.58 GHz to 0.989 GHz. It can be seen that... x The -3dB bandwidth under directional polarization is greater than y The -3dB bandwidth under directional polarized waves is due to the wide-angle domain stability of the planar FSS structure.

[0048] Figure 5 This demonstrates the effect of the conical FSS structure along the incident wave. z In the negative direction of the axis, y and x Transmission coefficient under directional polarization. When half-angle... β When it reaches 30°, at y and x Resonant frequency shift rate under directional polarization wave | k f_c The percentages are 1.18% and 0.98% respectively, with a bandwidth of -3dB. BW The bandwidth was reduced from 1.58 GHz to 1.32 GHz and 1.35 GHz, respectively. It can be seen that the change in -3 dB bandwidth under these conditions is less than the change along the incident wave direction. z The -3dB bandwidth variation in the positive axis direction is due to the different transmission paths generated under different incident wave directions. From Figure 4 and Figure 5 It can be seen that when β reaches 30°, the conical FSS structure has good conformal stability when electromagnetic waves are incident along both the negative and positive z-axis directions.

[0049] After determining the top-level bandpass structure with high conformal stability, the bottom-level feed structure design is required. The initial conical TFSS unit structure is as follows: Figure 6 As shown, considering the size of the varactor diode (SMV2201-040LF), a strip needs to be added inside the outer hexagonal ring of the top bandpass structure to make the gap g3 = 0.3mm. The bottom feed structure consists of three strips with overlapping centers and an outer hexagonal ring. The dielectric substrate is F4B with a thickness t of 0.25mm. In this TFSS structure, the cathode of the varactor diode is connected to the outer square ring of the top layer, and the anode is connected to the bottom hexagonal ring through a via. The specific geometric dimensions are as follows: p =15mm, g 1 = 2.664 mm g 2 = 0.30mm, l 1 = 4.275mm, l 2 = 2.62mm, l 3 = 5mm, l 4 = 3.0mm m = 2mm, d 1 = 2.7mm d 2 = 0.7mm, s = 0.50mm.

[0050] Figure 7The simulated transmission coefficients of the initial conical TFSS unit structure under planar array and oblique electromagnetic wave incidence are presented, with a junction capacitance of 0.21 pF. The varactor diode is equivalent to a series combination of parasitic resistance and junction capacitance. Under perpendicular incidence, the structure generates an IL of 0.84 dB. When the incident wave angle increases to 60°, the resonant frequency offset |kf_θ| is 1.21% under TE polarized wave incidence; however, under TM polarized wave incidence, strong parasitic resonances appear in the low-frequency band of the passband, severely damaging the transmission performance of the target transmission passband.

[0051] To improve the wide-angle stability of the conical TFSS cell structure in a planar array, a cell bend method is employed to increase the miniaturization of the bottom-layer feed structure. Simultaneously, to reduce the inductance (IL) of the TFSS structure, the equivalent inductance of the inner strips in the top layer needs to be reduced. Based on this, and considering conformal stability constraints, the bent strips in the top layer are replaced with patches, and the bottom strips undergo first-order bending. The material and thickness of the dielectric substrate, as well as the position of the varactor diode, remain unchanged. The final conical TFSS cell structure is shown below. Figure 8 As shown, the corresponding geometric dimensions are: hexagonal periodic dimensions p = 15mm, the gap between the outer hexagonal ring and the inner hexagonal patch of the top layer. g 1 = 2.664mm, the size of the loaded varactor diode. g 2 = 0.30mm, the width of the metal patch for placing the varactor diode. l 1 = 4.275mm, the length of the metal patch for placing the varactor diode. l 2 = 2.62mm, the length of the first-order bend of the bottom curved strip. l 3 = 5mm l 4 = 3.0mm, the width of the patch connected to the hexagonal ring at the top edge. m = 2mm, width of the hexagonal ring at the top edge d 1 = 2.7mm, the width of the hexagonal ring at the bottom edge. d 2 = 0.7mm, and the width of the bottom curved strip s = 0.50mm.

[0052] The cone-shaped tunable frequency selectable surface structure has a hexagonal periodic shape; it consists of a top bandpass structure, a dielectric substrate, metal vias, and a bottom feed structure. The top bandpass structure comprises an outer hexagonal ring and an inner deformed hexagonal patch. The outer hexagonal ring connects six square patches, each of which can overlap after rotating 60°. The inner deformed hexagonal patch consists of a hexagonal patch and six "arrow-like" patterns located at the corners of the hexagon. The center positions of the outer hexagonal ring and the inner deformed hexagonal patch are the same. The bottom feed structure consists of an outer hexagonal ring and an inner bent metal patch. Composition: The internal curved metal patch consists of 6 metal strips with first-order bends, each of which can be rotated 60° to coincide with the next curved metal strip; the bottom hexagonal ring and the bottom internal curved metal patch are centered at the same position; 6 varactor diodes are placed in the gap formed by the top outer hexagonal ring and the top internal deformed hexagonal patch; the 6 varactor diodes are connected in parallel; the anodes of the 6 varactor diodes are connected to the top outer hexagonal ring; the cathodes of the 6 varactor diodes are connected to the center of the 6 bottom curved metal strips with first-order bends through a metal through-hole located at the center.

[0053] Figure 9 The simulated transmission coefficients of the designed TFSS cell structure in a planar array are shown. When the junction capacitance value... C 11 When the resonant frequency is increased from 0.21pF to 0.55pF, the resonant frequency... f p As the IL value decreased from 3.06 GHz to 2.55 GHz, it increased from 0.33 dB to 1.71 dB.

[0054] Table 1 shows the IL values ​​of the initial and final TFSS cells of the conical surface in the planar array when different varactor diodes (SMV2201-040LF and MA46580-1209) are applied. The parasitic resistances of SMV2201-040LF and MA46580-1209 are also included. R 11 The Ω and 1Ω are respectively 5.41Ω and 1Ω. It can be seen that compared to the initial TFSS structure, the final TFSS structure has a smaller IL value, and when the varactor diode is SMV2201-040LF, C 11 When the value is 0.21pF, the IL value can be reduced by up to 60.7%.

[0055] Table 1. IL values ​​of initial and final TFSS elements on a conical surface in a planar array. Note #: Loading varactor diode SMV2201-040LF; Note : Loading varactor diode MA46580-1209.

[0056] To reveal the working mechanism of this TFSS structure, a corresponding ECM was established, such as... Figure 10 As shown. The outer hexagonal rings of the top and bottom layers can be made of inductors respectively. L 01 and L 02 Equivalently, the top layer internal surface mount is composed of an inductor L 10 Equivalently, the bottom curved strip is made of inductance L 20 Equivalent, L T This is the equivalent inductance of the dielectric substrate. C 10 This refers to the gap capacitance between the outer hexagonal ring and the inner surface mount of the top layer. C 20 The coupling capacitance between the underlying stripes is represented by the varactor diode, which is equivalent to the parasitic resistance. R 11 Series junction capacitance C 11 .

[0057] By fitting Figure 9 middle C 11 The simulated transmission coefficient at 0.21 pF yielded the following fitted circuit parameter values: L 01 =3.75nH L 10 = 0.92nH, C 10 = 0.212pF L 02 = 4.51nH, L 20 = 2.56nH, C 20 = 0.45pF. Figure 11 The comparison between the transmission coefficients calculated by ECM and the transmission coefficients simulated by CST is shown, and it can be seen that the two have a good agreement, which verifies the effectiveness of the established ECM.

[0058] Figure 12 The simulated transmission coefficients of this TFSS cell structure in a planar infinite array are shown when TE and TM polarized waves are obliquely incident. When the incident angle reaches 80°, the junction capacitance is... C 11 At 0.55 pF and 0.21 pF respectively, under TE polarization, such as Figure 12 As shown in (a) and (c), the resonant frequency offset rate | k f_θ | respectively 0.91% and 0.51%; under TM polarized waves, such as Figure 12 As shown in (b) and (d), the resonant frequency offset rate | k f_θ The values ​​are 0.63% and 0.65%, respectively. When the incident angle increases to 60°, weak parasitic resonances appear in the high-frequency band of the transmission passband under TE polarization; under TM polarization, parasitic resonances caused by the bending mode of the bottom strip appear in both the low-frequency and high-frequency bands of the transmission passband. However, since these parasitic resonances are far from the target frequency band, they have little impact on the performance of the target transmission passband. It can be seen that this TFSS element has good resonant frequency stability in a planar infinite array within the incident angle range of 0-80°.

[0059] To verify the transmission performance stability of the designed TFSS structure under conical conformal transformation, a corresponding planar sector prototype was fabricated, such as... Figure 13 As shown in (a), the radius ξ It is 230mm, and the central angle is... δ It is 240°. Figure 13 (b) shows a schematic diagram of the conical TFSS structure with a half-angle of 41.9°, obtained by bending the planar fan-shaped TFSS structure conformally onto the conical foam. The conical TFSS structure was placed in the middle of the absorbing screen, and the transmission coefficient of the structure was tested using the free space method.

[0060] Figure 14 This is the transmission coefficient of the conical TFSS structure sample under perpendicular electromagnetic wave incidence. The varactor diode bias voltage is... V 11 When the voltage changes from 6V to 20V, under TE polarization, the resonant frequency is... f p As the frequency band increased from 2.54 GHz to 3.07 GHz, the inter-band transmission coefficient (IL) decreased from 1.89 dB to 0.34 dB. Within the 3.21-5.0 GHz frequency range, the out-of-band high-frequency transmission coefficient remained below -10 dB, demonstrating strong wideband out-of-band suppression capability. Under TM polarization, the resonant frequency... f p As the frequency increased from 2.52 GHz to 3.05 GHz, the inter-band transmission coefficient (IL) changed from 1.88 dB to 0.33 dB. Within the 3.06-5.0 GHz frequency range, the out-of-band high-frequency transmission coefficient remained below -10 dB. This shows that compared to... Figure 9 The transmission performance of the planar TFSS structure shown is relatively stable, while the transmission performance of the conical TFSS structure does not change much and exhibits high conformal stability.

[0061] Figure 15 The transmission coefficient of the conical TFSS sample under oblique electromagnetic wave incidence is shown. When the incident angle reaches 75°, V 11 At 6V, under TE and TM polarized waves, the resonant frequency of the conical TFSS sample shifted by 1.58% and 1.81%, respectively; when V 11 When the voltage is changed to 20V, the resonant frequency of the conical TFSS sample shifts by 1.31% and 0.78% under TE and TM polarized waves, respectively. Therefore, it can be concluded that this conical TFSS structure has stable transmission performance within the 0-75° range. In summary, from... Figure 14 and Figure 15 It can be seen that the designed conical TFSS structure achieves high transmission stability. As shown in Table 1, in order to further reduce the IL value of the conical TFSS structure under large-angle incident TE polarized waves, a varactor diode with smaller parasitic resistance can be used.

[0062] Example 2 The purpose of this embodiment is to provide a stable, tapered, tunable frequency-selective surface design system, including: The determination module is configured to: determine the periodic shape and arrangement of the FSS based on the performance evolution law of the FSS under the conical conformal transformation; The design module is configured to: set the target IL value and design a conical tunable frequency selection surface structure based on the insertion loss improvement strategy; The judgment module is configured to: determine whether the optimized conical tunable frequency selection surface structure meets the set target IL value; if the optimized conical tunable frequency selection surface structure meets the set target IL value, then end; if the optimized conical tunable frequency selection surface structure does not meet the set target IL value, then re-optimize the geometric parameter values ​​of the conical tunable frequency selection surface structure.

[0063] In further embodiments, the following is also provided: A server that can be used to execute the methods provided in the above embodiments. Specifically: A server includes a Central Processing Unit (CPU), system memory comprising Random Access Memory (RAM) and Read Only Memory (ROM), and a system bus connecting the system memory and the CPU. The server also includes a basic input / output system (I / O system) to facilitate information transfer between various components within the computer, and mass storage devices for storing the operating system, applications, and other program modules.

[0064] A basic input / output system includes a display for showing information and input devices such as a mouse and keyboard for user input. Both the display and the input devices are connected to the central processing unit via an input / output controller connected to the system bus. The basic input / output system may also include an input / output controller for receiving and processing input from multiple other devices such as a keyboard, mouse, or electronic stylus. Similarly, the input / output controller also provides output to a display screen, printer, or other types of output devices.

[0065] Mass storage devices are connected to the central processing unit via a mass storage controller (not shown) connected to the system bus. The mass storage devices and their associated computer-readable media provide non-volatile storage for the server. That is, mass storage devices may include computer-readable media (not shown) such as hard disks or CD-ROM (CompactDisc Read-Only Memory) drives.

[0066] Computer-readable media can include computer storage media and communication media. Computer storage media includes volatile and non-volatile, removable and non-removable media implemented using any method or technology for storing information such as computer-readable instructions, data structures, program modules, or other data. Computer storage media include RAM, ROM, EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable Programmable Read Only Memory), flash memory or other solid-state storage technologies, CD-ROM, DVD (Digital Versatile Disc) or other optical storage, magnetic tape cassettes, magnetic tape, disk storage, or other magnetic storage devices. Of course, those skilled in the art will understand that computer storage media are not limited to the above-mentioned types. The aforementioned system memories and mass storage devices can be collectively referred to as memory.

[0067] According to various embodiments of the present invention, the server can also connect to and operate on a remote computer on a network such as the Internet. That is, the server can connect to the network through a network interface unit connected to the system bus, or it can use a network interface unit to connect to other types of networks or remote computer systems (not shown).

[0068] The aforementioned memory also includes one or more programs, which are stored in the memory and configured to be executed by the CPU.

[0069] One embodiment provides a terminal that can be used to perform the methods provided in the above embodiments. The terminal may be a portable mobile terminal, such as a smartphone, tablet computer, MP3 player (Moving Picture Experts Group Audio Layer III), MP4 player (Moving Picture Experts Group Audio Layer IV), laptop computer, or desktop computer. The terminal may also be referred to by other names such as user terminal, portable terminal, laptop terminal, desktop terminal, etc.

[0070] Typically, a terminal includes a processor and memory.

[0071] The processor may include one or more processing cores, such as a quad-core processor or an octa-core processor. The processor may be implemented using at least one of the following hardware forms: DSP (Digital Signal Processing), FPGA (Field-Programmable Gate Array), or PLA (Programmable Logic Array). The processor may also include a main processor and coprocessors. The main processor, also known as the CPU (Central Processing Unit), is used to process data in the wake-up state; the coprocessor is a low-power processor used to process data in the standby state. In some embodiments, the processor may integrate a GPU (Graphics Processing Unit), which is responsible for rendering and drawing the content to be displayed on the screen. In some embodiments, the processor may also include an AI (Artificial Intelligence) processor, which handles computational operations related to machine learning.

[0072] The memory may include one or more computer-readable storage media, which may be non-transitory. The memory may also include high-speed random access memory and non-volatile memory, such as one or more disk storage devices or flash memory devices. In some embodiments, the non-transitory computer-readable storage media in the memory are used to store at least one instruction, which is executed by a processor to implement the sound reverberation method provided in the method embodiments of this application.

[0073] In some embodiments, the terminal may also optionally include: a peripheral device interface and at least one peripheral device. The processor, memory, and peripheral device interface can be connected via a bus or signal line. Each peripheral device can be connected to the peripheral device interface via a bus, signal line, or circuit board. Specifically, the peripheral device includes at least one of: a radio frequency circuit, a display screen, a camera assembly, an audio circuit, a positioning assembly, or a power supply.

[0074] Peripheral device interfaces can be used to connect at least one I / O (Input / Output) related peripheral device to the processor and memory. In some embodiments, the processor, memory, and peripheral device interface are integrated on the same chip or circuit board; in some other embodiments, any one or two of the processor, memory, and peripheral device interface can be implemented on separate chips or circuit boards, which is not limited in this embodiment.

[0075] Radio frequency (RF) circuits are used to receive and transmit RF signals, also known as electromagnetic signals. RF circuits communicate with communication networks and other communication devices via electromagnetic signals. RF circuits convert electrical signals into electromagnetic signals for transmission, or convert received electromagnetic signals back into electrical signals. Optionally, RF circuits include: antenna systems, RF transceivers, one or more amplifiers, tuners, oscillators, digital signal processors, codec chipsets, user identity module cards, etc. RF circuits can communicate with other terminals through at least one wireless communication protocol. These wireless communication protocols include, but are not limited to: the World Wide Web, metropolitan area networks, intranets, various generations of mobile communication networks (2G, 3G, 4G, and 5G), wireless local area networks, and / or WiFi (Wireless Fidelity) networks. In some embodiments, the RF circuit may also include circuitry related to NFC (Near Field Communication), which is not limited in this application.

[0076] The display screen is used to display the UI (User Interface). This UI can include graphics, text, icons, videos, and any combination thereof. When the display screen is a touch screen, it also has the ability to collect touch signals on or above the surface of the display. These touch signals can be input as control signals to a processor for processing. In this case, the display screen can also be used to provide virtual buttons and / or a virtual keyboard, also known as soft buttons and / or a soft keyboard. In some embodiments, there can be one display screen, which serves as the front panel of the terminal; in other embodiments, there can be at least two display screens, respectively disposed on different surfaces of the terminal or in a folded design; in still other embodiments, the display screen can be a flexible display screen, disposed on a curved or folded surface of the terminal. Furthermore, the display screen can be configured as a non-rectangular, irregular shape, i.e., a non-rectangular screen. The display screen can be made of materials such as LCD (Liquid Crystal Display) and OLED (Organic Light-Emitting Diode).

[0077] A camera assembly is used to capture images or videos. Optionally, the camera assembly includes a front-facing camera and a rear-facing camera. Typically, the front-facing camera is located on the front panel of the terminal, and the rear-facing camera is located on the back of the terminal. In some embodiments, there are at least two rear-facing cameras, which are any one of a main camera, a depth-sensing camera, a wide-angle camera, and a telephoto camera, to achieve background blurring by fusion of the main camera and the depth-sensing camera, panoramic shooting by fusion of the main camera and the wide-angle camera, VR (Virtual Reality) shooting, or other fusion shooting functions. In some embodiments, the camera assembly may also include a flash. The flash can be a single-color temperature flash or a dual-color temperature flash. A dual-color temperature flash refers to a combination of a warm-light flash and a cool-light flash, which can be used for light compensation at different color temperatures.

[0078] The audio circuitry may include a microphone and a speaker. The microphone is used to collect sound waves from the user and the environment, converting them into electrical signals that are input to a processor for processing, or to radio frequency (RF) circuitry for voice communication. For stereo sound acquisition or noise reduction purposes, multiple microphones may be used, positioned at different locations on the terminal. The microphone may also be an array microphone or an omnidirectional microphone. The speaker is used to convert electrical signals from the processor or RF circuitry into sound waves. The speaker may be a traditional diaphragm speaker or a piezoelectric ceramic speaker. When the speaker is a piezoelectric ceramic speaker, it can convert electrical signals not only into audible sound waves but also into inaudible sound waves for purposes such as distance measurement. In some embodiments, the audio circuitry may also include a headphone jack.

[0079] The positioning component is used to determine the current geographical location of the terminal to enable navigation or LBS (Location Based Service). The positioning component can be based on the US GPS (Global Positioning System), China's BeiDou system, or Russia's Galileo system.

[0080] The power supply is used to power the various components in the terminal. The power supply can be alternating current (AC), direct current (DC), a disposable battery, or a rechargeable battery. When the power supply includes a rechargeable battery, it can be a wired or wirelessly rechargeable battery. A wired rechargeable battery is charged via a wired connection, while a wirelessly rechargeable battery is charged via a wireless coil. The rechargeable battery can also be used to support fast charging technology.

[0081] In some embodiments, the terminal further includes one or more sensors. These one or more sensors include, but are not limited to, accelerometers, gyroscopes, pressure sensors, fingerprint sensors, optical sensors, and proximity sensors.

[0082] An accelerometer can detect the magnitude of acceleration along the three axes of a coordinate system established by the terminal. For example, an accelerometer can be used to detect the components of gravitational acceleration along the three axes. The processor can then control the touchscreen to display the user interface in either landscape or portrait view based on the gravitational acceleration signals acquired by the accelerometer. Accelerometers can also be used for collecting motion data in games or for other applications.

[0083] The gyroscope sensor can detect the terminal's orientation and rotation angle. It can work in conjunction with an accelerometer to capture the user's 3D movements on the terminal. Based on the data collected by the gyroscope sensor, the processor can perform the following functions: motion sensing (e.g., changing the UI based on the user's tilt), image stabilization during shooting, game control, and inertial navigation.

[0084] The pressure sensor can be located on the side bezel of the terminal and / or under the touchscreen display. When the pressure sensor is located on the side bezel, it can detect the user's grip signal on the terminal, and the processor can perform left / right hand recognition or quick operation based on the grip signal collected by the pressure sensor. When the pressure sensor is located under the touchscreen display, the processor can control the operable controls on the UI interface based on the user's pressure on the touchscreen display. Operable controls include at least one of button controls, scroll bar controls, icon controls, or menu controls.

[0085] A fingerprint sensor is used to collect a user's fingerprint. The processor identifies the user based on the fingerprint collected by the sensor, or vice versa. When the user's identity is verified as trusted, the processor authorizes the user to perform relevant sensitive operations, including unlocking the screen, viewing encrypted information, downloading software, making payments, and changing settings. The fingerprint sensor can be located on the front, back, or side of the terminal. When the terminal has physical buttons or a manufacturer's logo, the fingerprint sensor can be integrated with those buttons or the logo.

[0086] An optical sensor is used to collect ambient light intensity. In one embodiment, the processor can control the display brightness of the touch screen based on the ambient light intensity collected by the optical sensor. Specifically, when the ambient light intensity is high, the display brightness of the touch screen is increased; when the ambient light intensity is low, the display brightness of the touch screen is decreased. In another embodiment, the processor can also dynamically adjust the shooting parameters of the camera assembly based on the ambient light intensity collected by the optical sensor.

[0087] A proximity sensor, also known as a distance sensor, is typically located on the front panel of a terminal. It is used to detect the distance between the user and the front of the terminal. In one embodiment, when the proximity sensor detects that the distance between the user and the front of the terminal is gradually decreasing, the processor controls the touchscreen display to switch from a screen-on state to a screen-off state; conversely, when the proximity sensor detects that the distance between the user and the front of the terminal is gradually increasing, the processor controls the touchscreen display to switch from a screen-off state to a screen-on state.

[0088] Those skilled in the art will understand that the structure shown does not constitute a limitation on the terminal, and may include more or fewer components than shown, or combine certain components, or employ different component arrangements.

[0089] An electronic device includes a memory and a processor, as well as computer instructions stored in the memory and running on the processor. When executed by the processor, the computer instructions perform the method described in Embodiment 1. For brevity, further details are omitted here.

[0090] It should be understood that in this embodiment, the processor can be a central processing unit (CPU), or it can be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor, etc.

[0091] Memory may include read-only memory and random access memory, and provides instructions and data to the processor. A portion of memory may also include non-volatile random access memory. For example, memory may also store information about the device type.

[0092] A computer-readable storage medium for storing computer instructions, which, when executed by a processor, perform the method described in Embodiment 1.

[0093] The method in Embodiment 1 can be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules within the processor. The software modules can reside in readily available storage media in the art, such as random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, or registers. This storage medium is located in memory; the processor reads information from the memory and, in conjunction with its hardware, completes the steps of the above method.

[0094] The computer storage medium of this embodiment can be any combination of one or more computer-readable media. The computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. For example, a computer-readable storage medium can be—but is not limited to—an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of computer-readable storage media (a non-exhaustive list) include: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this document, a computer-readable storage medium can be any tangible medium that contains or stores a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0095] Computer-readable signal media may include data signals propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. Computer-readable signal media may also be any computer-readable medium other than computer-readable storage media, capable of sending, propagating, or transmitting programs for use by or in connection with an instruction execution system, apparatus, or device.

[0096] Program code contained on a computer-readable medium may be transmitted using any suitable medium, including—but not limited to—wireless, wire, optical fiber, RF, etc., or any suitable combination thereof.

[0097] Computer program code for performing the operations of this invention can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, as well as conventional procedural programming languages ​​such as "C" or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0098] A computer program product includes a computer program that, when executed by a processor, implements the method described in Embodiment 1.

[0099] The present invention also provides at least one computer program product tangibly stored on a non-transitory computer-readable storage medium. The computer program product includes computer-executable instructions, such as instructions included in program modules, which execute in a device on a target real or virtual processor to perform the processes / methods described above. Typically, program modules include routines, programs, libraries, objects, classes, components, data structures, etc., that perform specific tasks or implement specific abstract data types. In various embodiments, the functionality of program modules can be combined or divided among program modules as needed. The machine-executable instructions for the program modules can execute within a local or distributed device. In a distributed device, the program modules can reside in both local and remote storage media.

[0100] The computer program code used to implement the methods of the present invention may be written in one or more programming languages. This computer program code may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that when executed by the computer or other programmable data processing device, the program code causes the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code may be executed entirely on a computer, partially on a computer, as a stand-alone software package, partially on a computer and partially on a remote computer, or entirely on a remote computer or server.

[0101] In the context of this invention, computer program code or related data may be carried by any suitable carrier to enable a device, apparatus, or processor to perform the various processes and operations described above. Examples of carriers include signals, computer-readable media, and the like. Examples of signals may include electrical, optical, radio, sound, or other forms of propagation signals, such as carrier waves, infrared signals, etc.

[0102] Those skilled in the art will recognize that the units and algorithm steps described in conjunction with the embodiments herein can be implemented in electronic hardware or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0103] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for designing a high-performance, tunable, frequency-selective conical surface, characterized in that, include: Based on the performance evolution law of FSS under conical conformal transformation, the periodic shape and arrangement of FSS are determined; Set the target IL value and design a cone-shaped tunable frequency selection surface structure based on the insertion loss improvement strategy; Determine whether the optimized cone-shaped tunable frequency selection surface structure meets the set target IL value; If the optimized cone-shaped tunable frequency selection surface structure meets the set target IL value, then the process ends; If the optimized conical tunable frequency selection surface structure does not meet the set target IL value, then the geometric parameter values ​​of the conical tunable frequency selection surface structure should be re-optimized.

2. The method for designing a stable, tunable, frequency-selective conical surface as described in claim 1, characterized in that, The top bandpass structure of the designed conical tunable frequency selective surface unit has a hexagonal periodic shape and is arranged in a triangular pattern.

3. The method for designing a stable, tunable, conical surface for frequency selection as described in claim 1, characterized in that, The top bandpass structure of the conical tunable frequency selective surface element was determined through simulation, specifically as follows: Simulation of the transmission coefficients of conical FSS structures with different half-angles β under polarized waves in the y and x directions when the incident wave is along the positive z-axis; Simulation of the transmission coefficients of conical FSS structures with different half-angles β under polarized waves in the y and x directions when the incident wave is along the negative z-axis. Based on the simulation results, the half-angle β of the conical FSS structure with good conformal stability when electromagnetic waves are incident along both the negative and positive z-axis directions was determined, and the top bandpass structure with high conformal stability was determined.

4. The method for designing a stable, tunable, frequency-selective conical surface as described in claim 3, characterized in that, The simulation calculation process for the transmission coefficient is as follows: Calculate the far-field reflection coefficient of a finite large frequency selective structure in the transmission direction; Calculate the total field in the transmission direction of the air layer with the same dimensions as the finite large frequency selective structure; The transmission coefficient of the finite large frequency selective structure can be obtained by subtracting the total field of the air layer with the same size as the finite large frequency selective structure in the transmission direction from the far-field reflection coefficient of the finite large frequency selective structure obtained by simulation in the transmission direction.

5. The method for designing a stable, tunable, conical surface for frequency selection as described in claim 3, characterized in that, After determining the top bandpass structure with high conformal stability, the bottom feed structure is designed. Taking into account the size of the varactor diode, a strip is added inside the hexagonal ring outside the top bandpass structure. The bottom feed structure consists of three strips with overlapping centers and an outer hexagonal ring, resulting in the initial conical TFSS unit structure.

6. The method for designing a stable, tunable, frequency-selective conical surface as described in claim 5, characterized in that, Based on the initial conical TFSS unit structure, the miniaturization of the underlying power supply structure is increased by adopting a unit zigzag method.

7. The method for designing a stable, tunable, frequency-selective conical surface as described in claim 5, characterized in that, Based on the initial conical TFSS unit structure, and considering conformal stability constraints, the curved strip inside the top bandpass structure is changed to a patch, and the bottom feed structure strip is bent in the first order. The material and thickness of the dielectric substrate and the position of the loaded varactor diode remain unchanged, resulting in a conical tunable frequency selective surface unit structure.

8. The method for designing a stable, tunable, frequency-selective conical surface as described in claim 1, characterized in that, The designed cone-shaped tunable frequency selection surface structure has a hexagonal periodic shape and consists of a top bandpass structure, a dielectric substrate, metal vias, and a bottom feed structure. The top bandpass structure consists of an outer hexagonal ring and an inner deformed hexagonal patch; the center positions of the outer hexagonal ring and the inner deformed hexagonal patch are the same; the bottom feed structure consists of an outer hexagonal ring and an inner bent metal patch; the inner bent metal patch is composed of a metal strip with a first-order bend; the center positions of the bottom hexagonal ring and the bottom inner bent metal patch are the same.

9. The method for designing a stable, tunable, frequency-selective conical surface as described in claim 8, characterized in that, The varactor diode is placed in the gap formed by the outer hexagonal ring of the top layer and the deformed hexagonal patch inside the top layer; the anode of the varactor diode is connected to the outer hexagonal ring of the top layer, and the cathode of the varactor diode is connected to the center of the bottom layer bent metal strip with first-order bending through a metal through-hole located at the center position; multiple varactor diodes are connected in parallel.

10. A method for designing a high-performance, tunable, frequency-selective conical surface as described in any one of claims 1-9, characterized in that, An equivalent circuit model is established for the designed conical tunable frequency selective surface. The effectiveness of the established equivalent circuit model is verified by comparing the transmission coefficient calculated by the equivalent circuit model with the simulated transmission coefficient.

11. A method for designing a high-performance, tunable, frequency-selective conical surface as described in any one of claims 1-9, characterized in that, The first constraint for reducing the IL value of the curved TFSS structure is that the frequency point at which the impedance matching between the bottom-level feed structure and the top-level bandpass structure is achieved should not exceed the transmission pole of the top-level bandpass structure. The second constraint for reducing the IL value of the curved TFSS structure is to ensure that the top-level bandpass structure has a small IL value.

12. A high-performance, tunable, frequency-selective surface design system for a conical surface, characterized in that, include: The determination module is configured to: determine the periodic shape and arrangement of the FSS based on the performance evolution law of the FSS under the conical conformal transformation; The design module is configured to: set the target IL value and design a conical tunable frequency selection surface structure based on the insertion loss improvement strategy; The judgment module is configured to: determine whether the optimized cone-shaped tunable frequency selection surface structure meets the set target IL value; If the optimized cone-shaped tunable frequency selection surface structure meets the set target IL value, then the process ends; If the optimized conical tunable frequency selection surface structure does not meet the set target IL value, then the geometric parameter values ​​of the conical tunable frequency selection surface structure should be re-optimized.

13. An electronic device, characterized in that, It includes a memory and a processor, as well as computer instructions stored in the memory and running on the processor, which, when executed by the processor, perform a performance-stable tapered tunable frequency-selective surface design method as described in any one of claims 1-11.

14. A computer-readable storage medium, characterized in that, Used to store computer instructions, which, when executed by a processor, complete the performance-stable tapered tunable frequency selective surface design method according to any one of claims 1-11.

15. A computer program product, characterized in that, The invention includes a computer program that, when executed by a processor, implements a performance-stable tapered tunable frequency-selective surface design method according to any one of claims 1-11.

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