Hexagonal dual-polarized high-selectivity frequency selective surface

Abstract

The application discloses a hexagonal dual-polarized high-selectivity frequency selective surface, which comprises an intermediate filtering layer and two magneto-electric dipole antennas, and the cross section is hexagonal; the two magneto-electric dipole antennas have the same structure and are symmetrically arranged about the intermediate filtering layer; the intermediate filtering layer is an intermediate metal layer with a central slot, the shape of the intermediate metal layer is a regular hexagon, the central slot is composed of a central hexagonal hollow and six edge slots respectively extending outward from the six sides of the hexagonal hollow, and each edge slot is directed to an end point of the regular hexagonal shape of the intermediate metal layer; the intermediate filtering layer serves as a band-pass filter, transmits electromagnetic waves at resonance and realizes suppression of low-frequency and high-frequency stop bands, and simultaneously serves as a common ground plane of the two magneto-electric dipole antennas. The application can solve the problems of high insertion loss of a wave transmission window of an existing frequency selective surface, insufficient out-of-band suppression, excessively wide transition band and poor angle stability.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic field and microwave technology, and specifically relates to a hexagonal dual-polarization high-selectivity frequency selective surface. Background Technology

[0002] High-selective frequency-selective surfaces (HFSSs) refer to surfaces that achieve high selectivity through methods such as introducing resonant cavities and multi-layer cascading. High selectivity typically refers to a filter response with a flatter passband, steeper sidebands, and no high-order resonances over a wider out-of-band frequency range. This is usually achieved by introducing multiple transmission poles within the passband to improve passband flatness and introducing transmission zeros at the passband edges to achieve sideband jitter cutoff and out-of-band suppression. HFSS radomes can reduce the impact on in-band antenna performance and improve out-of-band stealth performance, making them of significant research value.

[0003] Patent CN114498061A discloses a frequency selective surface unit, a frequency selective surface, and a frequency selection method. The advantages of the high-selectivity frequency selective surface proposed in this patent are wide passband, low profile, and dual-polarization application. The disadvantages are narrow stopband bandwidth and only angular stability of TE polarization.

[0004] The paper “Filtenna-Filter-Filtenna-Based FSS With Simultaneous Wide Passband and Wide Out-of-Band Rejection Using Multiple-Mode Resonators” proposes a quadrilateral high-selectivity frequency selective surface based on FA-F-FA. The advantages of its FSS structure are that it has a wide passband and stopband and a narrow transition band. The disadvantage is that it only has angular stability of TE polarization.

[0005] Many high-selectivity frequency-selective surfaces have been studied, but they still suffer from problems such as high insertion loss within the transmission window, insufficient out-of-band suppression, and poor angular stability, which means that the performance of current high-selectivity frequency-selective surfaces needs to be improved. Summary of the Invention

[0006] In order to overcome the shortcomings of the prior art, the present invention aims to provide a hexagonal dual-polarization high-selectivity frequency selective surface, in order to solve one or all of the problems of high insertion loss in the transmission window, insufficient out-of-band suppression, excessively wide transition band, and poor angular stability of the existing frequency selective surface.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A hexagonal dual-polarization high-selectivity frequency selective surface includes an intermediate filter layer and two magnetoelectric dipole antennas, with a hexagonal cross-section;

[0009] The two magnetoelectric dipole antennas have the same structure and are symmetrically arranged about the intermediate filter layer. The intermediate filter layer is an intermediate metal layer with a central slot. The shape of the intermediate metal layer is a regular hexagon. The central slot consists of a hexagonal cutout located in the center and six side slots extending outward from the six sides of the hexagonal cutout. Each side slot faces one end of the regular hexagonal shape of the intermediate metal layer. The intermediate filter layer acts as a bandpass filter, which transmits electromagnetic waves at resonance and achieves low-frequency and high-frequency stopband suppression. At the same time, it serves as the common ground plane for the two magnetoelectric dipole antennas.

[0010] In one embodiment, the two magnetoelectric dipole antennas are antenna one and antenna two. Antenna one includes a top metal layer, and antenna two includes a bottom metal layer. The top metal layer and the bottom metal layer have the same shape and structure, both being hexagons composed of six identical isosceles triangular metal patches. There is a first gap between adjacent isosceles triangular metal patches on the same horizontal plane. Two isosceles triangular metal patches on the same projection plane are connected by a metal pillar, which passes through the middle metal layer.

[0011] In one embodiment, the top metal layer is located on the upper surface of the hexagonal first dielectric layer, and the bottom metal layer is located on the lower surface of the hexagonal third dielectric layer. There are equal-sized second gaps between the six isosceles triangular metal patches that make up the top metal layer and the edge of the first dielectric layer, and between the six isosceles triangular metal patches that make up the bottom metal layer and the edge of the third dielectric layer.

[0012] In one embodiment, the intermediate metal layer is located on the lower surface of the first dielectric layer or the upper surface of the hexagonal second dielectric layer, wherein the first dielectric layer, the second dielectric layer, and the third dielectric layer have the same shape and size and are projected opposite each other.

[0013] In one embodiment, the first dielectric layer and the third dielectric layer have the same relative permittivity, but the first dielectric layer has a different relative permittivity than the second dielectric layer; the first dielectric layer and the third dielectric layer have the same loss tangent, but the second dielectric layer has a different loss tangent.

[0014] In one embodiment, a metal ring is provided in each of the six side slots, and the middle metal layer is composed of a metal sheet obtained by slotting the center, opening the edges and opening the ends of a hexagonal metal block, and the metal rings.

[0015] The metal ring is connected to the metal sheet, and the edge opening is provided at the midpoint of each of the six sides of the hexagonal metal block. The end opening is provided at the six end points of the hexagonal metal block.

[0016] The first and second openings have different sizes. The first and second openings introduce new transmission zeros at high frequencies, enhancing the out-of-band suppression effect of the high-frequency stopband.

[0017] In one embodiment, both the first opening and the second opening are rectangular, with the length of the first opening being less than the length of the second opening and the width being less than the width of the second opening.

[0018] In one embodiment, the metal sheet has six circular openings, each located at the line connecting the center of the hexagonal metal block and the center of the first opening. The circular openings are used for the metal column to pass through and connect the two magnetoelectric dipole antennas.

[0019] In one embodiment, the metal ring is composed of five metal strips connected in sequence, wherein metal strip one, metal strip three and metal strip five are parallel and perpendicular to metal strip two and metal strip four, and are located on the same side of metal strip two, and metal strip two and metal strip four are located on the same side of metal strip three.

[0020] Metal strip three and metal strip five are of equal length and are shorter than the length of metal strip one; the length of metal strip four is shorter than the length of metal strip two.

[0021] One end of metal strip one is connected to a metal sheet, and the other end is connected to metal strip two, metal strip three, metal strip four and metal strip five in sequence. The end of metal strip five is connected to metal strip two and has a gap with metal strip one.

[0022] In one embodiment, the metal strip is perpendicularly connected to the metal sheet, that is, the metal strip is perpendicularly connected to the side groove where it is located.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] First, compared to conventional high-selectivity frequency selective surfaces based on magnetoelectric dipoles (antenna-filter-antenna type), this invention employs an overall hexagonal structure, enabling angular stability for both TE and TM dual polarization. Specifically, when a TM wave is obliquely incident, a quadrilateral magnetoelectric dipole-based high-selectivity frequency selective surface will induce common-mode resonance in the passband or differential-mode resonance in the high-frequency stopband, leading to performance degradation in both the passband and stopband—that is, the appearance of transmission zeros in the passband or transmission poles in the stopband. The hexagonal structure, however, can significantly suppress common-mode resonance in the passband or differential-mode resonance in the high-frequency stopband, thereby achieving angular stability for both TE and TM dual polarization.

[0025] Secondly, compared with a typical high-selectivity frequency selective surface, the present invention introduces two types of through holes at the edge. Since the high-frequency stopband has high-order resonances that affect the high-frequency stopband suppression effect, and two high-order resonance frequency points appear before and after, two different sizes of openings are made to generate transmission zeros at two different frequency points, thereby suppressing the high-order resonances at the two frequency points respectively, thereby enhancing the high-frequency out-of-band suppression effect and making the structure have better out-of-band suppression and a wider stopband.

[0026] Third, compared to typical high-selectivity frequency selective surfaces, this invention has a narrower transition band, a wider passband, and lower insertion loss. The narrower transition band is achieved by controlling the positions of the low-frequency transmission zero generated by the magnetoelectric dipole and the high-frequency transmission zero generated by the "e"-shaped metal ring in the intermediate layer. The wider passband and lower insertion loss are achieved through multimode resonance technology, which excites the four modes of the magnetoelectric dipole antenna. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the overall structure of the high-selectivity frequency-selective surface of the present invention.

[0028] Figure 2 This is a structural diagram of the top / bottom metal layer of the high-selectivity frequency selective surface of the present invention.

[0029] Figure 3 This is a schematic diagram showing the dimensions of the top / bottom metal layers of the high-selectivity frequency selective surface of the present invention.

[0030] Figure 4 This is a structural diagram of the second metal layer of the high-selectivity frequency-selective surface of the present invention.

[0031] Figure 5 This is a structural diagram showing the dimensions of the second metal layer of the high-selectivity frequency-selective surface of the present invention.

[0032] Figure 6 This is the transmission coefficient curve under TE / TM polarization when the incident wave is incident at an incident angle of 0° in Embodiment 1 of the present invention.

[0033] Figure 7 These are the transmission coefficient curves of Embodiment 1 of the present invention under different incident angles of the incident wave, where (a) is the transmission coefficient curve under TE polarization and (b) is the transmission coefficient curve under TM polarization. Detailed Implementation

[0034] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings and examples.

[0035] As mentioned earlier, existing high-selectivity frequency selective surfaces still face some challenges in terms of transmission window, out-of-band suppression, and angular stability. To address these issues, this invention provides a hexagonal dual-polarization high-selectivity frequency selective surface based on multimode resonance technology. This surface features a wide passband and a wide stopband, while maintaining polarization and angular stability in both the passband and stopband. It is suitable for wireless communication systems in complex electromagnetic environments, such as radar, radomes, and aircraft stealth applications.

[0036] For details, please refer to [link / reference]. Figures 1-5 As shown, the present invention discloses a hexagonal dual-polarization high-selectivity frequency selective surface, which includes two magnetoelectric dipole antennas and an intermediate filter layer. The device as a whole has a hexagonal prism structure, that is, the cross-section is hexagonal. Obviously, the hexagon referred to in the present invention should be a regular hexagon in actual engineering.

[0037] The two magnetoelectric dipole antennas of this invention have identical structures and are connected back-to-back, i.e., symmetrically arranged about the intermediate filter layer, and are connected through the intermediate filter layer by connecting components. This forms an antenna-filter-antenna (AFA) structure. This invention, through two back-to-back magnetoelectric dipole antennas and a ground plane embedded in the filter, utilizes a combination of magnetic (M) dipole and electric (E) dipole modes, possessing an inherent high-pass filtering response and wide operating bandwidth. Broadband out-of-band suppression in both the low and high bands is controlled by the central slot and six rotationally symmetrical closed "e"-shaped rings in the intermediate filter layer. Furthermore, two different sized vias form additional "LC" series resonances to eliminate higher-order mode resonances, further enhancing high-frequency out-of-band suppression. The ground plane also plays a crucial role in the impedance matching of the FSS.

[0038] The intermediate filter layer of the present invention is an intermediate metal layer 13 with a central slot. The intermediate metal layer 13 is in the shape of a regular hexagon, with the central slot located at the center of the hexagon. Its shape is similar to that of a snowflake, consisting of a central hexagonal cutout and six side slots extending outward from the six sides of the hexagonal cutout. Specifically, it can be formed by rotating a rectangular slot co-centered with the intermediate metal layer 13 by 60°, 120°, or 180° around the center. Here, the angle is defined with the top and bottom sides of the regular hexagonal cutout as the 0° reference. That is, each side slot faces one end of the regular hexagonal shape of the intermediate metal layer 13. In other words, each end of the regular hexagonal shape corresponds one-to-one with the midpoint of each side of the hexagonal cutout.

[0039] According to the above structure, the intermediate filter layer acts as a bandpass filter, enabling electromagnetic waves to pass through at resonance while suppressing low-frequency and high-frequency stopbands. Simultaneously, the filter serves as the common ground plane for the two magnetoelectric dipole antennas, playing a crucial role in impedance matching. Therefore, this invention achieves transmission characteristics with both wide passband and wide external suppression, while maintaining polarization stability at the resonant frequency and angular stability of the dual polarization. It is suitable for wireless communication systems in complex electromagnetic environments and can be applied to radomes.

[0040] In a further embodiment of the present invention, the two magnetoelectric dipole antennas are designated as antenna one and antenna two, and reference is made again. Figures 1-5 As shown, antenna one includes a top metal layer 11, and antenna two includes a bottom metal layer 16. The top metal layer 11 and the bottom metal layer 16 have the same shape and structure, both being hexagons composed of six identical isosceles triangular metal patches. Figure 2 Patches 111, 112, 113, 114, 115, and 116 are centrally symmetrical. On the same horizontal plane, i.e., in the top metal layer 11 or the bottom metal layer 16, there is a first gap 117 between two adjacent isosceles triangular metal patches. The two patches of the top metal layer 11 and the bottom metal layer 16 on the same projection plane are tightly connected to the upper and lower surfaces of a metal pillar 17, which passes through the intermediate metal layer 13. In this invention, the upper half of the metal pillar 17 and the top metal layer 11 constitute antenna one, and the lower half of the metal pillar 17 and the bottom metal layer 16 constitute antenna two.

[0041] By adopting the above patch combination method, the preliminary design of a back-to-back hexagonal magnetoelectric dipole antenna was completed, realizing the basic functions of a receiving antenna and a transmitting antenna.

[0042] In a further embodiment of the present invention, dielectric layers are designed for the top metal layer 11 and the bottom metal layer 16, respectively, referring again to Figures 1-5 As shown, the top metal layer 11 is located on the upper surface of the first dielectric layer 12, and the bottom metal layer 16 is located on the lower surface of the third dielectric layer 15. The cross-sections of the first dielectric layer 12 and the third dielectric layer 15 are obviously hexagonal, and their cross-sectional dimensions are larger than those of the top metal layer 11 and the bottom metal layer 16. As a result, second gaps 118 of equal size are formed between the six patches of the top metal layer 11 and the edge of the first dielectric layer 12, and between the six patches of the bottom metal layer 16 and the edge of the third dielectric layer 15.

[0043] Since the frequency selective surface has a periodic structure, the second gap 118 can separate adjacent magnetoelectric dipole units, allowing the frequency selective surface to function normally.

[0044] In a further embodiment of the present invention, the intermediate metal layer 13 can be directly disposed on the lower surface of the first dielectric layer 12, or a second dielectric layer 14 can be added thereon and disposed on the upper surface of the second dielectric layer 14. Obviously, the cross-section of the second dielectric layer 14 is also hexagonal. When the intermediate metal layer 13 is disposed on the lower surface of the first dielectric layer 12, the characteristic is that the intermediate metal layer 13 is directly connected to the first dielectric layer 12, and there is no air layer in between.

[0045] In this embodiment, the intermediate metal layer 13 is disposed on the upper surface of the second dielectric layer 14. At this time, the lower surface of the second dielectric layer 14 is in direct contact with the third dielectric layer 15. The first dielectric layer 12, the second dielectric layer 14, and the third dielectric layer 15 have the same shape and size, and their projections are opposite each other. The first dielectric layer 12 and the third dielectric layer 15 have the same relative permittivity and the same loss tangent. However, the relative permittivity of the second dielectric layer 14 is different from that of the first dielectric layer 12 and the third dielectric layer 15, and its loss tangent is different from that of the first dielectric layer 12 and the third dielectric layer 15.

[0046] In this embodiment, a second dielectric layer 14 is added, and an intermediate metal layer 13 is arranged on its upper surface. The feature is that the intermediate metal layer 13 is directly connected to the second dielectric layer 14, and there is no air layer in between.

[0047] In a further embodiment of the invention, refer again Figures 1-5 As shown, a metal ring 135 is disposed in each of the six side slots. The intermediate metal layer 13 consists of a metal sheet 136 obtained by slotting the center, creating edge holes, and creating end holes in a hexagonal metal block, and the metal rings 135. Specifically, the metal rings 135 are connected to the metal sheet 136. The edge holes refer to holes 131 located at the midpoints of the six sides of the hexagonal metal block, and the end holes refer to holes 132 located at the six endpoints of the hexagonal metal block. In this invention, holes 131 and 132 have different dimensions. Holes 131 and 132 introduce new transmission zeros at high frequencies, further enhancing the out-of-band suppression effect of the high-frequency stopband.

[0048] The metal ring 135 serves two purposes: first, it introduces a transmission zero close to the passband in the high-frequency stopband, enhancing out-of-band suppression and shortening the transition band between the passband and the high-frequency stopband, thus improving selectivity; second, it generates the fundamental transmission mode, participating in the construction of a flat passband on the frequency selectivity surface. Since higher-order resonances in the high-frequency stopband affect the high-frequency stopband suppression effect, a transmission zero is first constructed at this higher-order resonance using aperture 132 to suppress it. However, it is found that suppressing this higher-order resonance results in a new higher-order resonance at another frequency. Therefore, a transmission zero is constructed at the newly generated higher-order resonance using aperture 131, completing the final design. Thus, apertures 131 and 132 serve to construct transmission zeros and suppress higher-order resonances, thereby enhancing out-of-band suppression. Additionally, apertures 131 and 132 also improve the impedance matching between antennas 1 and 2, reducing the insertion loss in the passband.

[0049] Both the first aperture 131 and the second aperture 132 of this invention are rectangular in shape. The first aperture 131 is smaller than the second aperture 132; specifically, its length is less than the length of the second aperture 132, and its width is less than the width of the second aperture 132. Since higher-order resonances in the high-frequency stopband affect the high-frequency stopband suppression effect, resulting in two higher-order resonance frequency points, two apertures of different sizes are made to generate transmission zeros at two different frequency points, suppressing the higher-order resonances at the two frequency points respectively, thereby enhancing the high-frequency out-of-band suppression effect.

[0050] In a further embodiment of the invention, refer again Figures 1-5 As shown, the metal sheet 136 has six circular openings 133. Each circular opening 133 is located on the line connecting the center of the hexagonal metal block and the center of opening 131. One circular opening 133 is used for a metal post 17 to pass through and connect two magnetoelectric dipole antennas.

[0051] In a further embodiment of the invention, refer again Figures 1-5 As shown, the metal ring 135 is shaped like the letter "e" and is composed of five metal strips connected sequentially: metal strip 1351, metal strip 1352, metal strip 1353, metal strip 1354, and metal strip 1355. Adjacent metal strips are perpendicular to each other. That is, metal strips 1351, 1353, and 1355 are parallel and perpendicular to metal strips 21352 and 41354. Furthermore, metal strips 1351, 31353, and 1355 are on the same side of metal strip 21352, and metal strips 21352 and 41354 are on the same side of metal strip 1353. Metal strips 31353 and 1355 are of equal length and shorter than the length of metal strip 1351, while the length of metal strip 41354 is shorter than the length of metal strip 21352.

[0052] One end of metal strip 1351 is connected to metal sheet 136, specifically, it can be a perpendicular connection, that is, metal strip 1351 is perpendicularly connected to the groove it is located in. If described in the aforementioned rectangular groove format, then metal strip 1351 is perpendicular to the long side 1342 of the rectangular groove it is located in, and parallel to the short side 1341 of the rectangular groove it is located in. The other end of metal strip 1351 is sequentially connected to metal strip 2 1352, metal strip 3 1353, metal strip 4 1354, and metal strip 5 1355. The end of metal strip 5 1355 is connected to metal strip 2 1352 and has a gap from metal strip 1351.

[0053] The “e”-shaped metal rings 135 used in this embodiment are a total of 6, with identical structures. They can be formed by rotating an “e”-shaped metal ring that is co-centered with the intermediate metal layer 13 around the center by 60°, 120°, 180°, 240°, or 300°.

[0054] In general, in a detailed embodiment of the present invention, from top to bottom, it mainly includes a top metal layer 11, a first dielectric layer 12, an intermediate metal layer 13, a second dielectric layer 14, a third dielectric layer 15, a bottom metal layer 16, and a metal pillar 17. The bottom metal layer 16 is located on the lower surface of the third dielectric layer 15 and is exactly the same as the top metal layer 11. The radius of the metal pillar 17 is the radius of the circular opening 131, and it passes through the circular opening 131 to connect the top metal layer 11 and the bottom metal layer 16.

[0055] The first dielectric layer 12 and the third dielectric layer 15 adopt a regular hexagonal structure of Rogers RO4350 with a relative permittivity of 3.66 and a side length W1 = 7.5 mm. The thickness of the first dielectric layer 12 is H1 = 2.9 mm and the thickness of the third dielectric layer 15 is H3 = 2.9 mm. The second dielectric layer 14 adopts a regular hexagonal structure of Rogers RO4003 with a relative permittivity of 3.55 and a side length W1 = 7.5 mm. The thickness of the second dielectric layer 14 is H2 = 0.1 mm.

[0056] The isosceles triangular patch of the top metal layer 11 has a height a1 = 6.065 mm, a distance a2 = 6.195 mm from the vertex to the edge of the hexagonal dielectric plate, a base length W2 = 7 mm, and a width W3 = 0.3 mm for the first gap 117.

[0057] The rectangular slot of the intermediate metal layer 13 has a width of Lr = 6.8 mm and a width of Wr = 2 mm. The width of each metal strip in the metal ring 135 is W4 = 0.2 mm. The lengths of metal strip 1351, metal strip 2 1352, metal strip 3 1353, metal strip 4 1354 and metal strip 5 1355 are L1 = 1.85 mm, L2 = 1.51 mm, L3 = 1.7 mm, L4 = 1.15 mm and L5 = 1.5 mm, respectively. The dimensions of opening 131 are WS1 = 1.5 mm and LS1 = 1.8 mm. The dimensions of opening 2 132 are WS2 = 1.6 mm and LS2 = 2.3 mm. The diameter of the circular opening 133 is Dvia = 1.4 mm. The distance between the two symmetrical circular openings 133 is Dele = 7 mm.

[0058] The bottom metal layer 16 has the same structure as the top metal layer 11.

[0059] The effects of this invention can be further illustrated by the following simulations:

[0060] I. Simulation Software:

[0061] Commercial Ansoft HFSS19.0 software.

[0062] II. Simulation Content:

[0063] Simulation 1, Embodiment 1 of the present invention, transmission coefficient curve when the incident wave is incident at an incident angle of 0°, simulation results under TE polarization / TM polarization are as follows. Figure 6 As shown. By Figure 6 As can be seen, Example 1 achieves a -1dB passband of 4.56-7.33GHz, a -1dB bandwidth of 46.6%, a low-frequency -10dB stopband bandwidth of 0.1-4.35GHz, a high-frequency -10dB stopband bandwidth of 7.54-17.96GHz, a relative bandwidth of 175.2%, a low-frequency transition band (-3dB to -10dB) of 0.06GHz, and a high-frequency transition band (-3dB to -10dB) of 0.12GHz.

[0064] Simulation 2, Example 1 of the present invention, shows the transmission coefficient curves under different incident angles of the incident wave. The simulation results under TE polarization are as follows: Figure 7 As shown in (a), the simulation results under TM polarization are as follows: Figure 7 As shown in (b). From Figure 7 It can be seen that Example 1 can maintain a good passband (S) within a 30° incident angle under TE polarization. 21 >-3dB), the in-band insertion loss drops to 3.38dB at 45°, but the insertion loss at most frequencies within the passband remains less than 3dB, and the stopband angle stability is good. Under TM polarized oblique incidence, it can achieve a 30° (S 21The proposed FSS maintains a good passband within an incident angle of >-3dB. At 45°, the in-band insertion loss decreases to 4.64dB, but the insertion loss at most frequencies within the passband remains less than 3dB. While its out-of-band suppression capability is not as good as that under TE polarization, it can still achieve a suppression effect of -10dB within 18GHz. Therefore, the proposed FSS can maintain a relatively stable response within a 30° oblique incident angle range, making it flexible for application to various types of radomes, with excellent angular stability in both the passband and stopband.

[0065] The above description is merely one embodiment of the present invention and does not constitute any limitation on the present invention. Obviously, those skilled in the art, after understanding the content and principles of the present invention, may make various modifications and changes in form and detail without departing from the principles and structure of the present invention. However, these modifications and changes based on the ideas of the present invention are still within the scope of the claims and protection of the present invention.

Claims

1. A hexagonal dual-polarization high-selectivity frequency-selective surface, characterized in that, It includes an intermediate filter layer and two magnetoelectric dipole antennas, with a hexagonal cross-section; The two magnetoelectric dipole antennas have the same structure and are symmetrically arranged about the intermediate filter layer. The intermediate filter layer is an intermediate metal layer (13) with a central slot. The intermediate metal layer (13) is hexagonal in shape. The central slot consists of a hexagonal cutout located in the center and six side slots extending outward from the six sides of the hexagonal cutout. Each side slot faces one end of the regular hexagonal shape of the intermediate metal layer (13). The intermediate filter layer acts as a bandpass filter, which transmits electromagnetic waves at resonance and suppresses low-frequency and high-frequency stopbands. It also serves as the common ground plane for the two magnetoelectric dipole antennas. The two magnetoelectric dipole antennas are antenna one and antenna two. Antenna one includes a top metal layer (11), and antenna two includes a bottom metal layer (16). The top metal layer (11) and the bottom metal layer (16) have the same shape and structure, both being hexagons composed of six identical isosceles triangular metal patches. There is a first gap (117) between adjacent isosceles triangular metal patches on the same horizontal plane. Two isosceles triangular metal patches on the same projection plane are connected by a metal column (17). A metal ring (135) is provided in each of the six side slots. The middle metal layer (13) is composed of a metal sheet (136) obtained by slotting the center, opening the edge and opening the end of the hexagonal metal block, and the metal ring (135). The metal ring (135) is connected to the metal sheet (136). The edge opening is provided at the midpoint of the six sides of the hexagonal metal block, and the end opening is provided at the six end points of the hexagonal metal block, respectively. The dimensions of the first opening (131) and the second opening (132) are different; The metal ring (135) is composed of five metal strips connected in sequence. Metal strip one (1351), metal strip three (1353) and metal strip five (1355) are parallel and perpendicular to metal strip two (1352) and metal strip four (1354). One end of metal strip one (1351) is connected to metal sheet (136), and the other end is connected to metal strip two (1352), metal strip three (1353), metal strip four (1354) and metal strip five (1355) in sequence. The end of metal strip five (1355) is connected to metal strip two (1352) and has a gap with metal strip one (1351).

2. The hexagonal dual-polarization high-selectivity frequency selective surface according to claim 1, characterized in that, The metal column (17) passes through the intermediate metal layer (13).

3. The hexagonal dual-polarization high-selectivity frequency selective surface according to claim 2, characterized in that, The top metal layer (11) is located on the upper surface of the hexagonal first dielectric layer (12), and the bottom metal layer (16) is located on the lower surface of the hexagonal third dielectric layer (15). There are equal-sized second gaps (118) between the six isosceles triangular metal patches that make up the top metal layer (11) and the edge of the first dielectric layer (12), and between the six isosceles triangular metal patches that make up the bottom metal layer (16) and the edge of the third dielectric layer (15).

4. The hexagonal dual-polarization high-selectivity frequency selective surface according to claim 3, characterized in that, The intermediate metal layer (13) is located on the lower surface of the first dielectric layer (12) or the upper surface of the hexagonal second dielectric layer (14). The first dielectric layer (12), the second dielectric layer (14) and the third dielectric layer (15) have the same shape and size and are projected opposite each other.

5. The hexagonal dual-polarization high-selectivity frequency selective surface according to claim 4, characterized in that, The first dielectric layer (12) and the third dielectric layer (15) have the same relative permittivity, but different relative permittivity from the second dielectric layer (14); the first dielectric layer (12) and the third dielectric layer (15) have the same loss tangent, but different loss tangent from the second dielectric layer (14).

6. The hexagonal dual-polarization high-selectivity frequency-selective surface according to any one of claims 1 to 5, characterized in that, The first aperture (131) and the second aperture (132) introduce new transmission zeros at high frequencies, enhancing the out-of-band suppression effect of the high-frequency stopband.

7. The hexagonal dual-polarization high-selectivity frequency selective surface according to claim 6, characterized in that, Both the first opening (131) and the second opening (132) are rectangular. The length of the first opening (131) is less than the length of the second opening (132), and the width is less than the width of the second opening (132).

8. The hexagonal dual-polarization high-selectivity frequency selective surface according to claim 6, characterized in that, The metal sheet (136) has six circular openings (133), each of which is located at the line connecting the center of the hexagonal metal block and the center of opening one (131). The circular openings (133) are used for the metal column (17) to pass through and connect the two magnetoelectric dipole antennas.

9. The hexagonal dual-polarization high-selectivity frequency selective surface according to claim 8, characterized in that, The first metal strip (1351), the third metal strip (1353), and the fifth metal strip (1355) are located on the same side of the second metal strip (1352), and the second metal strip (1352) and the fourth metal strip (1354) are located on the same side of the third metal strip (1353). Metal strip three (1353) and metal strip five (1355) are of equal length and shorter than the length of metal strip one (1351), and the length of metal strip four (1354) is shorter than the length of metal strip two (1352).

10. The hexagonal dual-polarization high-selectivity frequency-selective surface according to claim 8, characterized in that, The metal strip (1351) is perpendicularly connected to the metal sheet (136), that is, the metal strip (1351) is perpendicularly connected to the side groove where it is located.

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