Dual-passband frequency selective surface structure and dual-passband antenna cover

Abstract

The embodiment of the application discloses a kind of double-passband frequency selective surface structure and double-passband antenna cover, double-passband frequency selective surface structure includes: substrate, the first surface of substrate is formed with the periodic arrangement of multiple double-passband units.Each double-passband unit has center point, to define cross line with center point as origin, it will be divided into four quadrants with double-passband unit, four quadrants include first quadrant group and second quadrant group;Each double-passband unit includes: at least two first resonant elements, at least two first resonant elements are located in two quadrants of one of first quadrant group and second quadrant group respectively, and first resonant element is used to generate first resonant frequency;Multiple second resonant elements, multiple second resonant elements are arranged in two quadrants of the other of first quadrant group and second quadrant group respectively, and second resonant element is used to generate second resonant frequency, and second resonant frequency is higher than first resonant frequency.

Description

Technical Field

[0001] This application relates to the field of electromagnetic wave and microwave technology, and in particular to a dual-passband frequency selective surface structure and a dual-passband radome. Background Technology

[0002] Dual-passband frequency-selective surface structures in related technologies can achieve dual-passband characteristics using a multi-layer cascaded structure. The multi-layer cascaded structure generates two transmission passbands by stacking multiple metal layers and a dielectric substrate.

[0003] In this dual-passband frequency selective surface structure, the two passbands originate from interlayer coupling. When the frequency of one passband needs to be adjusted, the frequency of the other passband will also change accordingly. Designers cannot design and adjust the two passbands independently; they can only optimize the overall structure through repeated simulation experiments, resulting in a long design cycle and high design difficulty. In addition, the thickness of the multi-layer cascaded structure is large, making it difficult to manufacture. Summary of the Invention

[0004] This application discloses a dual-passband frequency selective surface structure. The two passbands of the dual-passband frequency selective surface structure can be designed independently, and the design difficulty is relatively low.

[0005] In a first aspect, this application provides a dual-passband frequency selective surface structure, comprising: a substrate, wherein a first surface of the substrate has a plurality of periodically arranged dual-passband units, each dual-passband unit having a center point, and mutually perpendicular cross lines defined with the center point as the origin dividing the dual-passband unit into four quadrants, the four quadrants including a first quadrant group opposite along a first diagonal and a second quadrant group opposite along a second diagonal; each dual-passband unit comprising: at least two first resonant elements disposed on the first surface of the substrate, the at least two first resonant elements being respectively located in two quadrants of one of the first quadrant group and the second quadrant group, the first resonant elements being used to generate a first resonant frequency; and a plurality of second resonant elements disposed on the first surface of the substrate, the plurality of second resonant elements being respectively located in two quadrants of the other of the first quadrant group and the second quadrant group, the second resonant elements being used to generate a second resonant frequency, the second resonant frequency being higher than the first resonant frequency.

[0006] In one possible implementation, the at least two first resonant elements are periodically arranged within the dual-passband unit with a first period size, the first period size being the center-to-center distance between the two first resonant elements along the extension direction of the target line in the cross-shaped line; the plurality of second resonant elements are periodically arranged within the dual-passband unit with a second period size, the second period size being the center-to-center distance between two adjacent second resonant elements along the extension direction of the target line. Wherein, the first period size is greater than or equal to the second period size.

[0007] In one possible implementation, the first period size p L With the second period size p H Between satisfy p L / p H It is an integer, and 1 ≤ p L / p H ≤4.

[0008] In some embodiments, the first period size p L Satisfying 15mm≤ p L ≤25mm; Second period dimension p H Satisfying 6mm≤ p H ≤12.5mm.

[0009] In one possible implementation, the at least two first resonant elements distributed in two quadrants of one of the first quadrant group and the second quadrant group are centrally symmetrical with respect to the center point; and / or the plurality of second resonant elements distributed in two quadrants of the other of the first quadrant group and the second quadrant group are centrally symmetrical with respect to the center point; and / or the areas of the four quadrants are equal.

[0010] In one possible implementation, the first resonant element includes a first metal square ring and a first metal patch located within the first metal square ring, with a gap between the first metal patch and the first metal square ring. The inner and outer edges of the first metal square ring are parallel to the edges of the dual-passband unit, and the edge of the first metal patch is parallel to the edge of the dual-passband unit. And / or the second resonant element includes a second metal square ring and a second metal patch located within the second metal square ring, with a gap between the second metal patch and the second metal square ring. The inner and outer edges of the second metal square ring are parallel to the edges of the dual-passband unit, and the edge of the second metal patch is parallel to the edge of the dual-passband unit.

[0011] In one possible implementation, the inner side length of the first metal square ring is... d L Satisfy: 10mm≤ d L≤24.8mm, the gap width between the first metal square ring and the first metal patch s L Satisfy: 0.1mm≤ s L ≤2mm; Inner side length of the second metal square ring d H Satisfies: 4mm≤ d H ≤12.3mm, the gap width between the second metal square ring and the first metal patch s H Satisfy: 0.1mm≤ s H ≤1mm.

[0012] In one possible implementation, the dual-passband frequency selective surface structure further includes a plurality of isolators spaced apart along the crosshairs and the outer edge of the dual-passband unit.

[0013] In one possible implementation, each of the isolation elements includes: a through-hole extending through the substrate, and a conductive material attached to the wall of the through-hole.

[0014] In one possible implementation, the relative permittivity of the substrate ranges from 1 to 4, the loss tangent angle of the substrate is tanδ < 0.02, and the thickness of the substrate ranges from 0.1 mm to 1.5 mm.

[0015] In one possible implementation, the first resonant element and the second resonant element are connected in series in the equivalent circuit model.

[0016] Secondly, embodiments of this application also provide a dual-passband radome, comprising: a radome body, the radome body comprising the dual-passband frequency selective surface structure provided in the first aspect of this application.

[0017] In the dual-passband frequency selective surface structure provided in this application embodiment, the first resonant element is concentrated in one set of opposing quadrants, and the second resonant element is concentrated in another set of opposing quadrants. The two types of resonant elements physically belong to different diagonal quadrants and each independently generates its own resonant frequency. When the first resonant frequency needs to be adjusted, the structural parameters of the first resonant element can be changed without significant change in the second resonant frequency. Similarly, when the second resonant frequency needs to be adjusted, the structural parameters of the second resonant element can be changed without significant change in the first resonant frequency. Designers can first independently design the structural parameters of the first resonant element to determine the first resonant frequency, then independently design the structural parameters of the second resonant element to determine the second resonant frequency, and then combine the two types of elements in the same dual-passband unit according to the aforementioned quadrant arrangement rules. The design process of the dual-passband frequency selective surface structure is transformed from overall optimization to step-by-step independent design, reducing design difficulty and shortening the design cycle.

[0018] Additional aspects and advantages of this application 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 this application. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is one of the structural schematic diagrams of a dual-passband unit in a dual-passband frequency selective surface structure provided in an embodiment of this application; Figure 2 This is a second schematic diagram of the structure of a dual-passband unit in a dual-passband frequency selective surface structure provided in an embodiment of this application; Figure 3 A schematic diagram of an equivalent circuit model of a dual-passband frequency-selective surface structure provided in an embodiment of this application; Figure 4 A transmission coefficient curve of a dual-passband frequency selective surface structure provided in this application under the condition of perpendicular incidence of TE polarized electromagnetic waves and TM polarized electromagnetic waves; Figure 5 A transmission coefficient curve of a dual-passband frequency selective surface structure provided in this application embodiment when the inner side length of the first metal square ring takes different values; Figure 6 A transmission coefficient curve of a dual-passband frequency selective surface structure provided in this application for different values ​​of the inner side length of the second metal square ring; Figure 7 A transmission coefficient curve of a dual-passband frequency selective surface structure provided in this application embodiment when the gap width between the first metal square ring and the first metal patch takes different values; Figure 8 The transmission coefficient curves of a dual-passband frequency selective surface structure provided in this application are shown when the gap width between the second metal square ring and the second metal patch takes different values.

[0021] Explanation of reference numerals in the attached figures: 1-Dual passband unit; 10-First resonant element; 101-First metal square ring; 102-First metal patch; 11-Second resonant element; 111-Second metal square ring; 112-Second metal patch; Through hole 12; First quadrant A; Second quadrant B; Third quadrant C; Fourth quadrant D. Detailed Implementation

[0022] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0024] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0025] Furthermore, the terms "installation," "setup," "equipped with," "connection," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0026] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, components, or parts (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, components, or parts. Unless otherwise stated, "a plurality of" means two or more.

[0027] like Figure 1 As shown, this application provides a dual-passband frequency selective surface structure, which can be applied to scenarios such as multi-frequency communication systems and radar radomes that require simultaneous transmission of two different frequency bands of electromagnetic waves.

[0028] The dual-passband frequency selective surface structure includes a substrate. The substrate can be a dielectric substrate. The substrate has a first surface facing away from each other along its thickness direction and a second surface opposite to the first surface. The substrate is used to support and provide structural support for the metal structure. The substrate can be made of a dielectric material, such as a polytetrafluoroethylene (PTFE) fiberglass laminate. The dielectric constant and thickness of the substrate can be selected according to the requirements of the operating frequency band.

[0029] A plurality of dual-passband units 1 are formed on the first surface of the substrate in a periodic arrangement. The periodic arrangement can be understood as a plurality of array arrangements; exemplarily, the plurality of dual-passband units 1 can be arranged at equal intervals along the first surface of the substrate in the X-axis and Y-axis directions to form an array arrangement. Each dual-passband unit 1 has the same structure. Adjacent dual-passband units 1 are adjacent to each other.

[0030] like Figure 1 As shown, each dual-passband unit 1 has a center point O. The center point can be understood as the geometric center of the dual-passband unit 1. For example, for a square dual-passband unit 1, its center point is located at the intersection of the two diagonals.

[0031] Define mutually perpendicular cross lines with the center point as the origin. These cross lines divide the dual-passband unit 1 into four quadrants. The cross lines can be understood as two mutually perpendicular line segments. One segment is parallel to the X-axis of the dual-passband unit 1, and the other is parallel to the Y-axis. These two line segments divide the dual-passband unit 1 into four regions, each called a quadrant. These four quadrants include the second quadrant (B) and the fourth quadrant (D) opposite each other along the first diagonal, and the first quadrant (A) and the third quadrant (C) opposite each other along the second diagonal.

[0032] The first diagonal can be understood as the direction of the diagonal connecting quadrant B and quadrant D. The second diagonal can be understood as the direction of the diagonal connecting quadrant A and quadrant C. The first and second diagonals are perpendicular to each other. Specifically, as... Figure 1As shown, the region enclosed by the center point as the origin and along the positive X-axis and positive Y-axis is the first quadrant A. The region enclosed by the negative X-axis and positive Y-axis is the second quadrant B. The region enclosed by the negative X-axis and negative Y-axis is the third quadrant C. The region enclosed by the positive X-axis and negative Y-axis is the fourth quadrant D.

[0033] Quadrant B and Quadrant D can be arranged opposite each other along the first diagonal, forming a first quadrant group. Quadrant A and Quadrant C can be arranged opposite each other along the second diagonal, forming a second quadrant group.

[0034] Each dual-passband unit 1 includes at least two first resonant elements 10. The first resonant element 10 can be a metal layer structure. The first resonant element 10 is disposed on a first surface of the substrate. The first resonant element 10 interacts with incident electromagnetic waves to generate resonance in the low-frequency band, thereby allowing the low-frequency electromagnetic waves to pass through. The first resonant element 10 may include a groove-shaped structure formed by removing part of the metal material, such as a square ring, annular ring, or other irregular groove structure. The size, structure, and shape of the first resonant element 10 determine its generated resonant frequency. The first resonant element 10 is used to generate a first resonant frequency.

[0035] At least two first resonant elements 10 may be located in two quadrants of either a first quadrant group or a second quadrant group. Specifically, in one embodiment, the first resonant elements 10 may be distributed in the first quadrant group, that is, a portion of the first resonant elements 10 may be disposed in the second quadrant B, and another portion of the first resonant elements 10 may be disposed in the fourth quadrant D. In another embodiment, the first resonant elements 10 may be distributed in the second quadrant group, that is, a portion of the first resonant elements 10 may be disposed in the first quadrant A, and another portion of the first resonant elements 10 may be disposed in the third quadrant C.

[0036] For example, such as Figure 1 As shown, each dual-passband unit 1 may include two first resonant elements 10. The two first resonant elements 10 may be respectively disposed in the second quadrant B and the fourth quadrant D. Alternatively, the two first resonant elements 10 may be respectively disposed in the first quadrant A and the third quadrant C.

[0037] The second resonant element 11 can be a metal layer structure. The second resonant element 11 is disposed on the first surface of the substrate. The second resonant element 11 interacts with the incident electromagnetic wave, generating resonance at a high frequency, thereby allowing the high-frequency electromagnetic wave to pass through. The second resonant element 11 may include a groove-shaped structure formed by removing part of the metal material, such as a square ring, annular ring, or other irregular groove structure. The size, structure, and shape of the second resonant element 11 determine its generated resonant frequency. The second resonant element 11 generates a second resonant frequency, which is higher than the first resonant frequency.

[0038] Multiple second resonant elements 11 are located in two quadrants of the other of the first and second quadrant groups. That is, the first resonant element 10 can be located in the second quadrant B and the fourth quadrant D, in which case the second resonant element 11 is located in the first quadrant A and the third quadrant C. Alternatively, the first resonant element 10 can also be located in the first quadrant A and the third quadrant C, in which case the second resonant element 11 is located in the second quadrant B and the fourth quadrant D. Both arrangements allow the first resonant element 10 and the second resonant element 11 to be distributed in different quadrant groups. In other words, the first resonant element 10 and the second resonant element 11 are not mixed in the same quadrant and belong to different diagonal quadrant groups in physical location. Designers can choose the arrangement method according to actual needs (such as power supply network layout, coordination with other devices, etc.) without affecting the performance of the dual-passband frequency selective surface structure.

[0039] Because the first resonant element 10 and the second resonant element 11 belong to different diagonal quadrants in physical location, they are spatially isolated. Therefore, the first resonant frequency generated by the first resonant element 10 and the second resonant frequency generated by the second resonant element 11 are independent of each other. When it is necessary to adjust the first resonant frequency, only the structural parameters (shape, size, etc.) of the first resonant element 10 need to be changed, while the structural parameters of the second resonant element 11 remain unchanged, and the second resonant frequency will not change significantly. Similarly, when it is necessary to adjust the second resonant frequency, only the structural parameters of the second resonant element 11 need to be changed, and the first resonant frequency will not change significantly.

[0040] For example, such as Figure 1 As shown, each dual-passband unit 1 can be provided with eight second resonant elements 11. Four of the second resonant elements 11 are located in the first quadrant A, and the other four are located in the third quadrant C. The second resonant elements 11 are small in size and can be used to generate a second resonant frequency in a higher frequency band.

[0041] Both the first resonant element 10 and the second resonant element 11 can be made of copper material and formed on the first surface of the substrate by an etching process.

[0042] In related technologies, regardless of whether a multi-layer cascaded structure or a single composite unit structure is used, the two transmission frequencies originate from mutual coupling within the same resonant system. In a multi-layer cascaded structure, there is interlayer electromagnetic coupling between the high-frequency layer and the low-frequency layer; changing the structural parameters of one layer will affect the resonant frequency of the other layer. In a single composite unit structure, the two frequencies originate from the composite resonance within the same unit; changing any structural parameter of the unit will simultaneously affect both frequencies. Therefore, the overall structure can only be optimized through repeated simulation experiments, resulting in a long design cycle and high design difficulty. In the dual-passband frequency selective surface structure of this application embodiment, the first resonant frequency and the second resonant frequency are independently generated by two types of resonant elements located in different diagonal quadrants. Therefore, the designer can first independently design the structural parameters of the first resonant element 10 to determine the first resonant frequency, then independently design the structural parameters of the second resonant element 11 to determine the second resonant frequency, and then combine the first resonant element 10 and the second resonant element 11 according to the above quadrant arrangement rules within the same dual-passband unit 1. In this way, the design process of the dual-passband frequency selective surface structure is transformed from overall optimization to step-by-step independent design, reducing design difficulty and shortening the design cycle.

[0043] Furthermore, multi-layer cascade schemes in related technologies require stacking multiple metal layers and dielectric substrates, resulting in a large overall thickness and complex processing steps. While single-composite-unit schemes have fewer layers, they require complex patterns such as nested rings and fractal structures within the unit, demanding high processing precision. In contrast, the dual-passband frequency selective surface structure of this application uses a single-layer metal structure, eliminating the need for stacking multiple metal layers and dielectric substrates, and avoiding complex nested structures. Only one layer of metal pattern is formed on the first surface of the substrate, consisting of multiple periodically arranged dual-passband units 1. Compared to multi-layer cascade schemes, the dual-passband frequency selective surface structure of this application has a smaller thickness and simpler processing. Compared to single-composite-unit schemes, the unit structure of the dual-passband frequency selective surface structure of this application is more regular, more flexible in design, has lower requirements for processing precision, and is easier to fabricate on a large area.

[0044] Thus, in the dual-passband frequency selective surface structure provided in this application embodiment, the first resonant element 10 is concentrated in one set of opposite quadrants, and the second resonant element 11 is concentrated in another set of opposite quadrants. The two types of resonant elements physically belong to different diagonal quadrants and each independently generates its own resonant frequency. When the first resonant frequency needs to be adjusted, the structural parameters of the first resonant element 10 can be changed without significant change in the second resonant frequency. When the second resonant frequency needs to be adjusted, the structural parameters of the second resonant element 11 can be changed without significant change in the first resonant frequency. Designers can first independently design the structural parameters of the first resonant element 10 to determine the first resonant frequency, then independently design the structural parameters of the second resonant element 11 to determine the second resonant frequency, and then combine the two types of elements in the same dual-passband unit 1 according to the above quadrant arrangement rules. The design process of the dual-passband frequency selective surface structure is transformed from overall optimization to step-by-step independent design, reducing design difficulty and shortening the design cycle.

[0045] In some embodiments, the at least two first resonant elements 10 are arranged periodically with a first period size within the dual passband unit 1.

[0046] The first period dimension can be understood as the center-to-center distance between the two first resonant elements 10 along the extension direction of the target line in the cross-shaped line. The target line can be a segment of the cross-shaped line, extending along the X-axis or the Y-axis. The distance between the center points of the two first resonant elements 10 along the extension direction of the target line, that is, along the X-axis or the Y-axis, is the first period dimension.

[0047] The distance between the center points of the two first resonant elements 10 can be obtained by measuring the coordinate difference between the center points of the two first resonant elements 10 in the direction of the target line.

[0048] like Figure 1 As shown, the centers of the two first resonant elements 10 are O1 and O2, respectively, and their first period dimensions are shown in the figure. p L In one implementation, such as Figure 1 As shown, when the first resonant element 10 is constructed as a square structure, and one first resonant element 10 is respectively disposed in the second quadrant B or the fourth quadrant D, the outer side length of the first resonant element 10 is the first period dimension. p L . p L The larger the value, the lower the first resonant frequency generated by the first resonant element 10. p L The smaller the value, the higher the first resonant frequency generated by the first resonant element 10.

[0049] In some embodiments, a plurality of second resonant elements 11 are arranged periodically in the second quadrant B or the fourth quadrant D with a second period size.

[0050] The second period dimension can be understood as the center-to-center distance between two adjacent second resonant elements 11 along the extension direction of the target line. The distance between the center points of two second resonant elements 11 along the extension direction of the target line, i.e., along the X-axis or Y-axis, is the second period dimension. The second period dimension can be obtained by measuring the coordinate difference between the center points of two adjacent second resonant elements 11 along the target line direction. Figure 1 As shown, the centers of the two second resonant elements 11 are O3 and O4, respectively, and their second period dimensions are shown in the figure. p H . p H The larger the value, the lower the second resonant frequency generated by the second resonant element 11. P H The smaller the value, the higher the second resonant frequency generated by the second resonant element 11.

[0051] The size of the first cycle is greater than or equal to the size of the second cycle. The ratio between the sizes of the first and second cycles can be selected according to the requirements of the operating frequency band.

[0052] The first period's size is larger than the second period's size, and the first resonant frequency is lower than the second resonant frequency, forming a frequency interval between them. The larger the difference between the first and second period's sizes, the larger the interval between the first and second resonant frequencies. Conversely, the smaller the difference, the smaller the interval. Designers can control the interval between the first and second resonant frequencies by adjusting the difference between the first and second period's sizes, ensuring that both frequencies fall within the desired frequency bands.

[0053] In this way, designers can control the interval between the first resonant frequency and the second resonant frequency by adjusting the size of the first cycle and the size of the second cycle.

[0054] In some embodiments, the first period size p L It can be 15mm-25mm. Second cycle size. p H It can be 6mm-12.5mm.

[0055] Will p L The value range is limited to between 15mm and 25mm. p HThe value range is limited to 6mm to 12.5mm, which allows the first resonant frequency to be in the range of 2.66GHz to 3.71GHz and the second resonant frequency to be in the range of 5.68GHz to 6.32GHz. This frequency range is suitable for S-band and C-band communication systems.

[0056] In some embodiments, p L =20mm, p H =10mm. When p L =20mm p H When the aperture is 10 mm, the first resonant frequency is approximately 3.20 GHz, and the second resonant frequency is approximately 5.94 GHz. The interval between the two frequencies is approximately 2.74 GHz. This interval allows the two transmission passbands to be separated, avoiding passband overlap.

[0057] In some embodiments, the first period size p L With the second period size p H The following condition must be met between them: 1≤ p L / p H ≤4.

[0058] when p L / p H When the value is 1, the size of the first period is equal to the size of the second period. At this time, the first resonant frequency generated by the first resonant element 10 is close to the second resonant frequency generated by the second resonant element 11, and the interval between the two frequencies is small.

[0059] when p L / p H When the value is 4, the size of the first period is four times the size of the second period. At this time, the interval between the first resonant frequency generated by the first resonant element 10 and the second resonant frequency generated by the second resonant element 11 is relatively large. If p L / p H When the value is greater than 4, the size of the first cycle is much larger than the size of the second cycle. The size of the first resonant element 10 is too large, which leads to an increase in the overall size of the dual-passband unit 1, which is not conducive to the miniaturization of the dual-passband frequency selective surface structure.

[0060] When 1≤ p L / pH When ≤4, the interval between the first resonant frequency and the second resonant frequency varies. p L / p H It increases with the increase of, and with p L / p H The size of the dual-passband unit 1 is reduced as the transmission frequency decreases. In this way, the size can be controlled within a reasonable range while ensuring that the two transmission frequencies are located in the desired frequency bands.

[0061] In one specific embodiment p L and p H The ratio is 2. That is, the size of the first period is twice the size of the second period. This ratio allows the first resonant element 10 and the second resonant element 11 to be arranged in a regular manner within the dual-passband unit 1. Two first resonant elements 10 and multiple second resonant elements 11 can be arranged exactly within the dual-passband unit 1 to form a complete periodic structure.

[0062] p L and p H The ratio is an integer. If p L and p H If the lengths are not integer multiples of each other, then the side length of dual-passband unit 1 in the target line direction may not be simultaneously equal to... p L and p H This mismatch leads to a misalignment or incomplete arrangement of the first resonant element 10 and the second resonant element 11. p L Set as p H The integer multiples of the number of elements can ensure that both types of resonant elements can form a complete periodic arrangement within the dual-passband unit 1, which facilitates the formation of a periodic array of metal patterns on the first surface of the substrate by multiple dual-passband units 1.

[0063] In some implementations, the at least two first resonant elements 10, located in two quadrants of either the first quadrant group or the second quadrant group, are centrally symmetrical with respect to the center point.

[0064] The following explanation uses the example of the first resonant element 10 being distributed in the first quadrant group, namely, in the second quadrant B and the fourth quadrant D. Central symmetry can be understood as follows: for each first resonant element 10 distributed in the second quadrant B, there is a corresponding first resonant element 10 in the fourth quadrant D. The line connecting the center points of this pair of first resonant elements 10 passes through the center point of the dual-passband unit 1, and the distances from the center points of the two first resonant elements 10 to the center point of the dual-passband unit 1 are equal. Alternatively, after rotating one first resonant element 10 180° around the center point of the dual-passband unit 1, that first resonant element 10 coincides with the other first resonant element 10.

[0065] In some implementations, the second resonant element 11, which is located in two quadrants of the other of the first quadrant group and the second quadrant group, is centrally symmetrical with respect to the center point.

[0066] Similarly, the following explanation uses the example of second resonant elements distributed in the second quadrant group, i.e., in the first quadrant A and the third quadrant C. Multiple second resonant elements 11 distributed in the first quadrant A and the third quadrant C are centrally symmetrical with respect to the center point of the dual-passband unit 1. For each second resonant element 11 distributed in the first quadrant A, there is a corresponding second resonant element 11 in the third quadrant C, and the line connecting the center points of these two second resonant elements 11 passes through the center point of the dual-passband unit 1. The distances from the center points of the two second resonant elements 11 to the center point of the dual-passband unit 1 are equal.

[0067] For example, taking the center point O of the dual-passband unit 1 as the origin, the second resonant element 11 is arranged in the first quadrant A and the third quadrant C, and the first resonant element 10 is arranged in the second quadrant B and the fourth quadrant D. Alternatively, the second resonant element 11 is arranged in the second quadrant B and the fourth quadrant D, and the first resonant element 10 is arranged in the first quadrant A and the third quadrant C. Both arrangements allow the first resonant element 10 and the second resonant element 11 to belong to different diagonal quadrant combinations, and are essentially equivalent.

[0068] The following explanation uses the example of second resonant element 11 located in the first quadrant A and the third quadrant C, and first resonant element 10 located in the second quadrant B and the fourth quadrant D. Each dual-passband unit 1 contains eight second resonant elements 11 and two first resonant elements 10. Of the eight second resonant elements 11, four are located in the first quadrant A and four are located in the third quadrant C. Of the two first resonant elements 10, one is located in the second quadrant B and one is located in the fourth quadrant D.

[0069] like Figure 2 As shown, the second resonant element 11 in the first quadrant A is arranged in the following positions. The center of the second resonant element 11a is located at coordinate ( ) in the first quadrant A. pH / 2,3× p H The center of the second resonant element 11b is located at coordinate (3×) within the first quadrant A. p H / 2,3× p H The center of the second resonant element 11c is located at coordinate ( / 2) within the first quadrant A. p H / 2, p H The center of the second resonant element 11d is located at coordinate (3×) within the first quadrant A. p H / 2, p H / 2) at this location. Among them, p H The period size of the second resonant element 11.

[0070] The first resonant element 10 in the second quadrant B is arranged in the following positions. The center of the first resonant element 10a is located at the coordinate (-) in the second quadrant B. p L / 2, p L / 2) at this location. Among them, p L The period size of the first resonant element 10.

[0071] The second resonant element 11 in the third quadrant C is obtained by rotating the second resonant element 11 in the first quadrant A by 180° around the center point of the dual-passband unit 1. Specifically, rotating the second resonant element 11a in the first quadrant A by 180° around the center point yields the second resonant element 11e in the third quadrant C. Rotating the second resonant element 11b in the first quadrant A by 180° around the center point yields the second resonant element 11f in the third quadrant C. Rotating the second resonant element 11c in the first quadrant A by 180° around the center point yields the second resonant element 11g in the third quadrant C. Rotating the second resonant element 11d in the first quadrant A by 180° around the center point yields the second resonant element 11h in the third quadrant C.

[0072] The first resonant element 10 in the fourth quadrant D is obtained by rotating the first resonant element 10 in the second quadrant B by 180° around the center point of the dual passband unit 1. Specifically, the first resonant element 10a located in the second quadrant B is rotated by 180° around the center point to obtain the first resonant element 10b located in the fourth quadrant D.

[0073] According to the above arrangement rules, the eight second resonant elements 11 and the two first resonant elements 10 are centrally symmetrically distributed within the dual-passband unit 1. The four second resonant elements 11 in the first quadrant A and the four second resonant elements 11 in the third quadrant C are centrally symmetrical about the center point. The one first resonant element 10 in the second quadrant B and the one first resonant element 10 in the fourth quadrant D are centrally symmetrical about the center point.

[0074] In some embodiments, such as Figure 1 and Figure 2 As shown, the areas of the four quadrants are equal. Each quadrant is a region divided by a perpendicular crosshair. Each crosshair consists of two perpendicular line segments, and the intersection of these two segments is the center point of the dual-passband unit 1. When the two line segments are perpendicular and their intersection point is located at the center of the dual-passband unit 1, the areas of the four regions are equal. This equal-area division ensures that the total area of ​​the first quadrant group (including the second quadrant B and the fourth quadrant D) is equal to the total area of ​​the second quadrant group (including the first quadrant A and the third quadrant C).

[0075] When the areas of the four quadrants are equal, the total area of ​​the region where the first resonant element 10 is located is equal to the total area of ​​the region where the second resonant element 11 is located. This is beneficial for balancing the arrangement of the two types of resonant elements within the limited area of ​​the dual-passband unit 1, ensuring that each type of resonant element has sufficient arrangement space, and facilitating the formation of a stable periodic arrangement for each type of resonant element.

[0076] With a fixed total area of ​​the dual-passband unit 1, if the areas of each quadrant are not equal, the number of resonant elements that can be arranged in the quadrant with the smaller area is limited, or the size of the resonant elements is restricted, resulting in a reduction in the design freedom of this type of resonant element.

[0077] Thus, when the first resonant element 10 and / or the second resonant element 11 are centrally symmetrically distributed relative to the center point, the overall structure of the dual-passband unit 1 possesses central symmetry. The central symmetry of the dual-passband unit 1 ensures that the dual-passband frequency-selective surface structure responds consistently to TE-polarized and TM-polarized electromagnetic waves. When the polarization direction of the incident electromagnetic wave changes, the transmission frequency and transmittance of the dual-passband frequency-selective surface structure remain stable.

[0078] In some embodiments, such as Figure 1 and Figure 2 As shown, the first resonant element 10 includes a first metal square ring 101 and a first metal patch 102 located within the first metal square ring 101.

[0079] The first metal square ring 101 can be a ring structure made of metal material. The first metal square ring 101 has an inner edge and an outer edge. The inner edge is the inner boundary of the first metal square ring 101, and the outer edge is the outer boundary of the first metal square ring 101. Both the inner and outer edges are square. The inner and outer edges of the first metal square ring 101 are parallel to the edges of the dual-passband unit 1. The edges of the dual-passband unit 1 can be understood as the outer boundary of the dual-passband unit 1, and this boundary can be square. When the inner and outer edges of the first metal square ring 101 are parallel to the edges of the dual-passband unit 1, the four sides of the first metal square ring 101 are parallel to the four sides of the dual-passband unit 1.

[0080] The first metal patch can be a square sheet structure made of metal. The first metal patch is located inside the first metal square ring 101 and coincides with the center of the first metal square ring 101. The edge of the first metal patch is parallel to the edge of the dual-passband unit 1. When the edge of the first metal patch is parallel to the edge of the dual-passband unit 1, the four sides of the first metal patch are parallel to the four sides of the dual-passband unit 1, respectively. This parallel structure allows the first resonant element 10 to produce the same response to electromagnetic waves polarized in both the X and Y directions, which is beneficial for achieving dual-polarization characteristics.

[0081] There may be a gap between the first metal square ring 101 and the first metal patch 102. This gap can be understood as the distance between the inner edge of the first metal square ring 101 and the outer edge of the first metal patch 102. No metal material is placed in this gap, that is, the first metal square ring 101 and the first metal patch 102 are physically separated from each other. In other words, the groove structure included in the first resonant element 10 is a square groove structure.

[0082] The first metal square ring 101 and the first metal patch 102 can be formed on the same metal layer by an etching process. Specifically, a metal layer is covered on the first surface of the substrate, and then the metal material between the first metal square ring 101 and the first metal patch 102 is removed by etching. The removed metal material forms a gap between the first metal square ring 101 and the first metal patch 102, that is, a square groove structure, thereby obtaining the first metal square ring 101 and the first metal patch 102 that are separated from each other.

[0083] The first metal square ring 101 and the first metal patch 102 together constitute the first resonant element 10. When an electromagnetic wave is incident on the first resonant element 10, the first metal square ring 101 and the first metal patch 102 jointly participate in resonance, generating a first resonant frequency. The value of the first resonant frequency is determined by the inner and outer side lengths of the first metal square ring 101, the side length of the first metal patch 102, and the gap width between them. Figure 1 and Figure 2In the example shown, the outer side length of the first metal square ring 101 is the first period size. p L .

[0084] like Figure 1 and Figure 2 As shown, the second resonant element 11 includes a second metal square ring 111 and a second metal patch 112 located within the second metal square ring 111.

[0085] The second metal square ring 111 can be a ring structure made of metallic material. The second metal square ring 111 has an inner edge and an outer edge. The inner edge is the inner boundary of the second metal square ring 111, and the outer edge is the outer boundary of the second metal square ring 111. Both the inner and outer edges are square. The inner and outer edges of the second metal square ring 111 are parallel to the edges of the dual-passband unit 1. This parallel structure allows the second resonant element 11 to produce the same response to electromagnetic waves polarized in both the X and Y directions, which is beneficial for achieving dual-polarization characteristics.

[0086] The second metal patch 112 can be a square sheet structure made of metal material. The second metal patch 112 is located inside the second metal square ring 111 and coincides with the center of the second metal square ring 111. The edge of the second metal patch 112 is parallel to the edge of the dual-band unit 1. There is a gap between the second metal square ring 111 and the second metal patch 112. There is no metal material in this gap, and the second metal square ring 111 and the second metal patch 112 are physically separated. That is, the groove structure included in the second resonant element 11 is a square groove structure. Both the second metal square ring 111 and the second metal patch 112 are made of metal material and are located on the first surface of the substrate. The gap between the second metal square ring 111 and the second metal patch 112, i.e., the square groove structure, can be formed on the metal layer by an etching process.

[0087] The second metal square ring 111 and the second metal patch 112 together constitute the second resonant element 11. When electromagnetic waves are incident on the second resonant element 11, the second metal square ring 111 and the second metal patch 112 jointly participate in resonance, generating a second resonant frequency. The value of the second resonant frequency is determined by the inner and outer side lengths of the second metal square ring 111, the side length of the second metal patch 112, and the gap width between them. Figure 1 and Figure 2 In the example shown, the outer side length of the second metal square ring 111 is the second period dimension. p H .

[0088] In some embodiments, the side length of the first metal square ring 101 is greater than the side length of the second metal square ring 111. The side length of the first metal patch 102 is greater than the side length of the second metal patch 112. Therefore, the first resonant frequency generated by the first resonant element 10 is lower than the second resonant frequency generated by the second resonant element 11. Designers can control the specific values ​​of the first and second resonant frequencies by adjusting the inner and outer side lengths of the metal square rings, the side lengths of the metal patches, and the gap width between them.

[0089] In this embodiment, both the first resonant element 10 and the second resonant element 11 adopt a structure of a square ring plus a metal patch. The gap between the metal square ring and the metal patch generates a capacitive effect, and the metal path of the metal square ring and the metal patch itself generates an inductive effect, together forming an LC resonant circuit. This LC resonant circuit resonates at a specific frequency, allowing electromagnetic waves of the corresponding frequency to pass through.

[0090] In some embodiments, the inner side length of the first metal square ring 101 is... d L Satisfy: 10mm≤ d L The gap width between the first metal square ring 101 and the first metal patch 102 is ≤24.8mm. s L Satisfy: 0.1mm≤ s L ≤2mm.

[0091] The inner side length of the first metal square ring 101 d L The inner side length is greater than that of the second metal square ring 111 d H The gap width between the first metal square ring 101 and the first metal patch 102 s L The gap width between the second metal square ring 111 and the second metal patch 112 s H They can be equal or unequal.

[0092] The gap between the first metal square ring 101 and the first metal patch 102 s L This can be understood as the ring width of the groove-shaped structure formed between the first metal square ring 101 and the first metal patch 102. In the first resonant element 10... p L and d L If it remains unchanged, s L The larger the value, the higher the resonant frequency of the first resonant element 10. sL The smaller the value, the lower the resonant frequency of the first resonant element 10.

[0093] when d L When the distance is less than 10 mm, the interval between the second resonant frequency and the second resonant frequency decreases, and the two transmission passbands may overlap. d L When the size is greater than 24.8mm, the size of the first resonant element 10 is too large, which may lead to an increase in the overall area of ​​the dual-passband unit 1.

[0094] Specifically, d L =19mm, s L =0.2mm.

[0095] In some embodiments, the inner side length of the second metal square ring 111 d H Satisfies: 4mm≤ d H ≤12.3mm, the gap width between the second metal square ring 111 and the second metal patch 112 s H Satisfy: 0.1mm≤ s H ≤1mm.

[0096] when d H When the size is less than 4mm, the second resonant element 11 is too small, increasing the requirements for processing precision and raising manufacturing costs. d H When the distance is greater than 12.3 mm, the interval between the frequency and the first resonant frequency decreases, and the two transmission passbands may overlap.

[0097] The gap between the second metal square ring 111 and the second metal patch 112 s H This determines the ring width of the groove structure formed between the second metal square ring 111 and the second metal patch 112. In the second resonant element 11... p H and d H If it remains unchanged, s H The larger the value, the higher the resonant frequency of the second resonant element 11. s H The smaller the value, the lower the resonant frequency of the second metal resonant element 11.

[0098] when s L Less than 0.1mm or sH When the gap is less than 0.1mm, the distance between the metal square ring and the metal patch is too narrow, increasing the processing difficulty and increasing the resistance of the first metal square ring 101 and the first metal patch 102, leading to increased insertion loss. s L Greater than 2mm or s H When the size is greater than 1mm, the size of the resonant element needs to be increased accordingly to achieve the required resonant frequency, which is not conducive to the miniaturization of dual-passband frequency selective surface structures.

[0099] Specifically, d H =9.5mm, s H =0.1mm.

[0100] Thus, in this embodiment of the application, the inner side length of the first metal square ring 101 is... d L The inner side length of the second metal square ring 111 is limited to the range of 10mm to 24.8mm. d H Limited to a range of 4mm to 12.3mm, the first resonant frequency can be located in the range of 2.66GHz to 3.71GHz, and the second resonant frequency in the range of 5.68GHz to 6.32GHz. This is suitable for S-band and C-band communication systems. The gap width between the first metal square ring 101 and the first metal sticker is adjusted. s L The gap width between the second metal square ring 111 and the second metal sticker is limited to a range of 0.1 mm to 2 mm. s H If the width is limited to the range of 0.1mm to 1mm, the slot structure in the first resonant element 10 and the second resonant element 11 has a sufficient and suitable width, so that the first resonant element 10 and the second resonant element 11 have accurate frequency tuning capability, good impedance matching and stable radiation performance, while avoiding problems such as manufacturing difficulties, bandwidth degradation or efficiency reduction caused by the slot structure being too narrow or too wide.

[0101] like Figure 1 and Figure 2 As shown, the dual-passband frequency selective surface structure also includes multiple isolators. These isolators are used to form an electromagnetic isolation structure within the substrate to reduce electromagnetic coupling between the first resonant element 10 and the second resonant element 11, as well as between different dual-passband units 1.

[0102] Multiple isolators are arranged at intervals along the crosshairs and the outer edge of the dual-passband unit. The isolators arranged along the crosshairs are located on the boundary between the first quadrant group and the second quadrant group, which can effectively reduce the electromagnetic coupling between the first resonant element 10 and the second resonant element 11, making the resonant frequencies generated by the two types of resonant elements more independent, which is conducive to realizing the independent design of the two transmission passbands.

[0103] Isolators arranged along the outer edge of the dual-passband unit 1 separate adjacent dual-passband units 1 from each other. When multiple dual-passband units 1 are periodically arranged on the first surface of the substrate, two adjacent dual-passband units 1 can share an outer edge. The isolators arranged along this outer edge are located between two adjacent dual-passband units 1, which can reduce the electromagnetic coupling between adjacent dual-passband units 1, enabling each dual-passband unit 1 to work independently and avoiding crosstalk between units from affecting the overall frequency selection performance.

[0104] In one implementation, the isolator can be a solid metal pillar embedded in the substrate, that is, a metal pin or metal needle pre-processed and directly embedded inside the substrate, arranged along a predetermined isolation path to form an electromagnetic barrier.

[0105] In another implementation, the isolation element can be a continuous or intermittent metal partition, that is, a metal sheet or metal wall extending along the isolation path is provided inside or on the surface of the substrate to achieve electromagnetic shielding.

[0106] Thus, by setting isolation elements along the cross lines and the outer edge of the dual passband unit 1, the mutual influence between the first resonant element 10 and the second resonant element 11 can be reduced, and the mutual influence between adjacent dual passband units 1 can also be reduced, so that the two types of resonant elements in each dual passband unit 1 can generate their respective resonant frequencies more independently, thereby improving the passband independence and design flexibility of the dual passband frequency selective surface structure as a whole.

[0107] In some embodiments, the insulating member includes through-holes and conductive material. Each through-hole 12 penetrates the substrate. The through-hole 12 can be a hole extending from a first surface of the substrate to a second surface of the substrate. The shape of the through-hole 12 can be circular or square. The diameter of the through-hole 12 can be selected according to processing capabilities and design requirements.

[0108] Each through-hole 12 has a conductive material attached to its wall. The conductive material can be copper, gold, silver, or other metals with conductive properties. The conductive material can be attached to the inner wall of the through-hole 12 via an electroplating process. The through-hole 12 with the conductive material attached to its wall can form a conductive path, connecting the conductive structures of the first and second surfaces of the substrate. In this embodiment, since no metal layer is provided on the second surface of the substrate, the conductive material on the wall of the through-hole 12 is mainly used to form an electromagnetic shielding structure.

[0109] Multiple through holes 12 are arranged at intervals along a cross line. Multiple through holes 12 are also arranged at intervals along the outer edge of the dual-passband unit 1. There is a gap between adjacent through holes 12, and the spacing between the through holes 12 can be selected according to isolation requirements.

[0110] The cross-shaped line consists of two mutually perpendicular line segments connected to the outer edge of the dual-passband unit 1. Along each line segment of the cross-shaped line, a plurality of through holes 12 are arranged at intervals. These through holes 12 are located on the cross-shaped line, meaning the center of each through hole 12 is located on the cross-shaped line.

[0111] Multiple through-holes 12 are also arranged at intervals along the outer edge of the dual-passband unit 1. The outer edge of the dual-passband unit 1 can be understood as the boundary line of the dual-passband unit 1. Each dual-passband unit 1 has four outer edges. Multiple through-holes 12 are arranged at intervals along each outer edge.

[0112] The through holes 12 arranged along the cross lines and the through holes 12 arranged along the outer edge can be connected to form a closed ring arrangement. Specifically, the through holes 12 arranged along the cross lines and the through holes 12 arranged along the outer edge meet at the intersection of the cross lines and the outer edge, so that the array of through holes 12 forms a closed isolation structure around the periphery of each quadrant.

[0113] The through-holes 12 arranged along the cross lines separate the first quadrant A, the second quadrant B, the third quadrant C, and the fourth quadrant D from each other. The first resonant element 10 is concentrated in the first quadrant group (such as the second quadrant B and the fourth quadrant D), and the second resonant element 11 is concentrated in the second quadrant group (such as the first quadrant A and the third quadrant C). The through-holes 12 arranged along the cross lines are located on the boundary line between the first and second quadrant groups, which can reduce the electromagnetic coupling between the first resonant element 10 and the second resonant element 11, making the resonant frequencies generated by the two types of resonant elements more independent.

[0114] Through-holes 12 arranged along the outer edge of the dual-passband unit 1 separate adjacent dual-passband units 1 from each other. When multiple dual-passband units 1 are periodically arranged on the first surface of the substrate, two adjacent dual-passband units 1 share an outer edge. The through-holes 12 arranged along this outer edge are located between two adjacent dual-passband units 1, which can reduce the electromagnetic coupling between adjacent dual-passband units 1 and enable each dual-passband unit 1 to work independently.

[0115] The walls of the through-holes 12 are coated with a conductive material, making the through-holes 12 conductive. These conductive through-holes 12 form vertically oriented conductive pillars inside the dielectric substrate, reflecting and shielding electromagnetic waves. Compared with the structure without through-holes 12, the electromagnetic isolation effect between different quadrants and between different dual-passband units 1 is improved after the conductive through-holes 12 are provided.

[0116] Thus, by providing conductive vias 12 along the cross lines and the outer edge of the dual-passband unit 1, the mutual influence between the first resonant element 10 and the second resonant element 11 can be reduced, as can the mutual influence between adjacent dual-passband units 1. This allows the two types of resonant elements within each dual-passband unit 1 to generate their respective resonant frequencies more independently, which is beneficial for achieving independent design of the two transmission passbands.

[0117] In some embodiments, the substrate has three parameters: relative permittivity, loss tangent, and thickness.

[0118] The relative permittivity of the substrate ranges from 1 to 4. The relative permittivity is the ratio of the substrate material's permittivity to the vacuum permittivity. The relative permittivity determines the degree of wavelength shortening of electromagnetic waves propagating within the substrate. A higher relative permittivity results in a shorter wavelength of electromagnetic waves within the substrate. Conversely, a lower relative permittivity results in a longer wavelength of electromagnetic waves within the substrate.

[0119] When the relative permittivity is 1, the dielectric properties of the substrate are close to those of air. When the relative permittivity is 4, the dielectric properties of the substrate are close to those of common dielectric substrates (such as FR4). Limiting the relative permittivity to the range of 1 to 4 allows the dual-passband frequency-selective surface structure to operate in the S-band and C-band, while ensuring the substrate is readily available. Specifically, a relative permittivity of 3.55 is used.

[0120] The loss tangent angle of the substrate, tanδ, is less than 0.02. The loss tangent angle can be used to measure the degree of energy loss of electromagnetic waves by the substrate material. The smaller the loss tangent angle, the less energy is lost when electromagnetic waves propagate in the substrate. The larger the loss tangent angle, the greater the energy loss when electromagnetic waves propagate in the substrate.

[0121] When the loss tangent is less than 0.02, the substrate exhibits lower absorption loss for electromagnetic waves, resulting in less energy attenuation when electromagnetic waves pass through the frequency-selective surface structure. This is beneficial for reducing the insertion loss of the dual-passband frequency-selective surface structure, allowing the electromagnetic waves within the transmission passband to maintain higher energy. Specifically, the substrate's loss tangent is tanδ = 0.0027.

[0122] The thickness of the substrate ranges from 0.1mm to 1.5mm. The substrate thickness can be considered as the perpendicular distance between the first and second surfaces of the substrate. The substrate thickness determines the path length for electromagnetic waves to propagate within the substrate and also affects the overall thickness of the frequency-selective surface structure.

[0123] When the substrate thickness is 0.1mm-1.5mm, the overall thickness of the dual-passband frequency selective surface structure is relatively small, making it suitable for applications with strict thickness requirements (such as conformal radomes and thin communication devices). Specifically, the substrate thickness can be 0.254mm.

[0124] Thus, with the substrate having relative permittivity, loss tangent, and thickness within the aforementioned ranges, the dual-passband frequency-selective surface structure can operate in the S-band and C-band. This frequency band is suitable for applications such as satellite communications and radar systems.

[0125] In some embodiments, such as Figure 3 As shown, the first resonant element 10 and the second resonant element 11 are connected in series in the equivalent circuit model. The equivalent circuit model can be a circuit model used to describe the electromagnetic characteristics of a dual-passband frequency-selective surface structure. In this equivalent circuit model, the first resonant element 10 is represented as a first resonant circuit, and the second resonant element 11 is represented as a second resonant circuit.

[0126] The equivalent circuit model corresponding to the dual-passband frequency selective surface structure described in this embodiment is as follows: The first resonant element 10 is equivalent to the first inductor. L 1L and the first capacitor C 1L A second inductor is then connected in parallel after being connected in series. L 2L That is, the first resonant circuit. Among them, the first inductor... L 1L and the first capacitor C 1L The series branch corresponds to the resonant path formed between the first metal square ring 101 and the first metal patch 102, and the second inductor L 2L This corresponds to the inductive effect of the first metal square ring 101 itself.

[0127] The second resonant element 11 is equivalent to the third inductor. L 1H Second capacitor C 1H A fourth inductor is then connected in parallel after being connected in series. L 2H This is the second resonant circuit. The third inductor... L 1H Second capacitor C 1H The series branch corresponds to the resonant path formed between the second metal square ring 111 and the second metal patch 112, the fourth inductor L 2H This corresponds to the inductive effect of the second metal square ring 111 itself.

[0128] For the first resonant circuit alone, its impedance The following relationship must be satisfied:

[0129] For a standalone second resonant circuit, its impedance The following relationship must be satisfied:

[0130] Separately and denominator and If the value is 0, the transmission poles of each individual circuit can be determined. The transmission poles of the first resonant circuit... The first resonant frequency corresponds to the first resonant frequency generated by the first resonant element 10. The transmission pole of the second resonant circuit. The second resonant frequency generated by the second resonant element 11, wherein, , .

[0131] The first resonant element 10 and the second resonant element 11 are connected in series. Series connection can be understood as electromagnetic waves passing sequentially through the first and second resonant circuits. For the series equivalent circuit model of the dual-passband frequency-selective surface mount structure corresponding to this embodiment, the overall impedance... The following relationship must be satisfied:

[0132] make Since the denominator is 0, its resonant poles can be obtained, which is the overall transmission passband of the dual-passband frequency-selective surface structure. The transmission passband of this embodiment... for × The solution is 0. Therefore, the solution of the series equivalent circuit model in this embodiment is the combination of the solutions of the first resonant circuit and the second resonant circuit.

[0133] Thus, the two transmission passbands of the dual-passband frequency-selective surface structure described in this embodiment are respectively connected to the transmission passband of the first resonant element 10. The transmission passband of the second resonant element 11 Consistent. When the first resonant circuit and the second resonant circuit are connected in series, the transmission poles of the equivalent circuit model of the dual-passband frequency selective surface structure are jointly determined by the transmission poles of the two resonant circuits. The transmission passband frequency of the equivalent circuit model is the combination of the transmission passband frequencies of the first and second resonant circuits. That is, the first resonant frequency generated by the first resonant circuit and the second resonant frequency generated by the second resonant circuit can both pass through the equivalent circuit model, forming two independent transmission passbands.

[0134] To verify the dual-polarization characteristics, dual-passband characteristics, and independent control characteristics of the two passbands of the dual-passband frequency selective surface structure provided in this embodiment, a full-wave simulation of the dual-passband frequency selective surface structure described in this embodiment was performed using simulation software. The results are as follows: Figures 4 to 8The transmission coefficient curve in the figure.

[0135] Figure 4 The transmission curves of the dual-passband frequency-selective surface structure provided in this application embodiment are shown under perpendicular incidence of TE-polarized electromagnetic waves and TM-polarized electromagnetic waves. Figure 4 As can be seen, the dual-passband frequency selective surface structure provided in this embodiment exhibits completely identical responses to vertically incident TE-polarized and TM-polarized electromagnetic waves. This dual-passband frequency selective surface structure provides two transmission passbands at 3.20 GHz and 5.94 GHz, respectively, with insertion losses of 0.03 dB and 0.12 dB, respectively. The relative bandwidths of the -3 dB transmission passbands of the two passbands are 33.0% and 10.7%, respectively.

[0136] The above results show that the dual-passband frequency selective surface structure provided in this embodiment has dual polarization characteristics, responds consistently to TE-polarized and TM-polarized electromagnetic waves, and has both low insertion loss and a wide passband bandwidth.

[0137] Figure 5 This illustrates changing the inner side length of the first metal square ring 101 while keeping other structural parameters constant. d L The transmission curves corresponding to the dual-passband frequency selection surface structure provided in this embodiment are shown for different values. d L We took four values: 18.4mm, 18.7mm, 19.0mm, and 19.3mm.

[0138] from Figure 5 It can be seen that, with d L Increasing the diameter from 18.4 mm to 19.3 mm shifts the center frequency of the first resonant frequency from 3.40 GHz to 3.06 GHz. Simultaneously, the center frequency of the second resonant frequency remains essentially unchanged at 5.94 GHz. This indicates that changing the structural parameters of the first resonant element 10, such as the inner side length of the first metal square ring 101, can control the first resonant frequency, and this control has no significant impact on the second resonant frequency.

[0139] Figure 6 This illustrates changing the inner side length of the second metal square ring 111 while keeping other structural parameters constant. d H The transmission curves corresponding to the dual-passband frequency selection surface structure provided in this embodiment are shown for different values. Figure 6 It can be seen that, with d HIncreasing the diameter from 9.3 mm to 9.6 mm shifts the second resonant frequency from 6.16 GHz to 5.76 GHz. Meanwhile, the first resonant frequency remains essentially unchanged at 3.20 GHz. This indicates that changing the structural parameters of the second resonant element 11, such as the inner side length of the second metal square ring 111, can control the second resonant frequency without significantly affecting the first resonant frequency.

[0140] Figure 7 This illustrates changing the gap width between the first metal square ring 101 and the first metal patch 102 while keeping other structural parameters constant. s L The transmission curves corresponding to the dual-passband frequency selection surface structure provided in this embodiment are shown for different values. Figure 7 It can be seen that, with s L Increasing the diameter from 0.1 mm to 0.4 mm shifts the first resonant frequency from 3.09 GHz to 3.38 GHz. Simultaneously, the second resonant frequency remains essentially unchanged at 5.94 GHz. This indicates that changing the structural parameters of the first resonant element 10, such as altering the gap width between the first metal square ring 101 and the first metal patch 102, will improve the resonant frequency. s L The first resonant frequency of the first resonant element 10 can be adjusted, and this adjustment does not have a significant effect on the second resonant frequency.

[0141] Figure 8 This illustrates changing the gap width between the second metal square ring 111 and the second metal patch 112 while keeping other structural parameters constant. s H The transmission curves corresponding to the dual-passband frequency selection surface structure provided in this embodiment are shown for different values. Figure 8 It can be seen that, with s H Increasing the diameter from 0.1 mm to 0.4 mm shifted the second resonant frequency from 5.94 GHz to 6.45 GHz. Meanwhile, the first resonant frequency remained essentially unchanged at 3.20 GHz. This indicates that changing the structural parameters of the second resonant element, such as altering the gap width between the second metal square ring 111 and the second metal patch 112, can improve the resonant frequency. s H The second resonant frequency of the second resonant element 11 can be adjusted, and this adjustment does not have a significant impact on the first resonant frequency.

[0142] A second aspect of this application also provides a dual-passband radome, including a radome body that includes the dual-passband frequency selective surface structure provided in any embodiment of the first aspect of this application. Since the dual-passband radome includes the dual-passband frequency selective surface structure, it possesses all the beneficial effects of the dual-passband frequency selective surface structure, which will not be elaborated further here.

[0143] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A dual-passband frequency selective surface structure, characterized in that, include: A substrate, wherein a first surface of the substrate is provided with a plurality of periodically arranged dual-passband units, each dual-passband unit having a center point, and mutually perpendicular cross lines are defined with the center point as the origin to divide the dual-passband unit into four quadrants, the four quadrants including a first quadrant group opposite along a first diagonal and a second quadrant group opposite along a second diagonal. Each of the dual passband units includes: At least two first resonant elements, the at least two first resonant elements being located in two quadrants of one of the first quadrant group and the second quadrant group, respectively, the first resonant elements being used to generate a first resonant frequency; A plurality of second resonant elements are respectively disposed in two quadrants of the first quadrant group and the second quadrant group. The second resonant elements are used to generate a second resonant frequency, which is higher than the first resonant frequency.

2. The dual-passband frequency selective surface structure according to claim 1, characterized in that, The at least two first resonant elements are arranged periodically within the dual-passband unit with a first period size, the first period size being the center-to-center distance between the two first resonant elements along the extension direction of the target line in the cross-shaped line. The plurality of second resonant elements are arranged periodically within the dual-passband unit with a second period size, the second period size being the center-to-center distance between two adjacent second resonant elements along the extension direction of the target line; Wherein, the first period size is greater than or equal to the second period size.

3. The dual-passband frequency selective surface structure according to claim 2, characterized in that, First period size p L With the second period size p H The following conditions must be met: p L / p H It is an integer, and 1 ≤ p L / p H ≤4.

4. The dual-passband frequency selective surface structure according to claim 1, characterized in that, The at least two first resonant elements, distributed in two quadrants of either the first quadrant group or the second quadrant group, are centrally symmetrical with respect to the center point; and / or The plurality of second resonant elements, distributed in two quadrants of the first quadrant group and the other of the second quadrant group, are centrally symmetrical with respect to the center point; and / or The areas of the four quadrants are equal.

5. The dual-passband frequency selective surface structure according to claim 1, characterized in that, The first resonant element includes a first metal square ring and a first metal patch located within the first metal square ring. A gap exists between the first metal patch and the first metal square ring. The inner and outer edges of the first metal square ring are parallel to the edges of the dual-passband unit, and the edge of the first metal patch is parallel to the edge of the dual-passband unit; and / or The second resonant element includes a second metal square ring and a second metal patch located inside the second metal square ring. There is a gap between the second metal patch and the second metal square ring. The inner edge and outer edge of the second metal square ring are parallel to the edge of the dual passband unit, and the edge of the second metal patch is parallel to the edge of the dual passband unit.

6. The dual-passband frequency selective surface structure according to claim 5, characterized in that, The inner side length of the first metal square ring d L Satisfy: 10mm≤ d L ≤24.8mm, the gap width between the first metal square ring and the first metal patch s L Satisfy: 0.1mm≤ s L ≤2mm; The inner side length of the second metal square ring d H Satisfies: 4mm≤ d H ≤12.3mm, the gap width between the second metal square ring and the second metal patch s H Satisfy: 0.1mm≤ s H ≤1mm.

7. The dual-passband frequency selective surface structure according to any one of claims 1 to 6, characterized in that, The dual-passband frequency selective surface structure further includes: Multiple isolators are spaced apart along the crosshairs and the outer edge of the dual passband unit.

8. The dual-passband frequency selective surface structure according to any one of claims 1 to 6, characterized in that, The relative permittivity of the substrate ranges from 1 to 4, the loss tangent tanδ of the substrate is less than 0.02, and the thickness of the substrate ranges from 0.1 mm to 1.5 mm.

9. The dual-passband frequency selective surface structure according to any one of claims 1 to 6, characterized in that, The first resonant element and the second resonant element are connected in series in the equivalent circuit model.

10. A dual-bandpass radome, characterized in that, include: The cover includes the dual passband frequency selective surface structure as described in any one of claims 1 to 9.

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