Frequency selective surface structure

Abstract

The application provides a frequency selective surface structure, which comprises a first metal layer, a dielectric substrate and a second metal layer, the dielectric substrate comprises a first surface and a second surface, the first surface and the second surface are oppositely arranged, the first metal layer is arranged on the first surface, and the second metal layer is arranged on the second surface; the first metal layer is formed with a cross aperture unit, a connecting aperture arranged on the circumferential side of the cross aperture unit and a zigzag aperture; the cross aperture unit and the zigzag aperture are communicated through the connecting aperture; the zigzag aperture extends periodically and is bent; and the second metal layer comprises a square patch unit. The structure effectively increases the electrical size through the zigzag design, realizes the miniaturization of the structure, maintains good filtering characteristics when electromagnetic waves are incident at a large angle, and is excellent in angle stability and polarization stability; and the square patch structure of the second metal layer is loaded, so that the frequency selection characteristics and the out-of-band suppression characteristics are improved.

Description

Technical Field

[0001] This application belongs to the field of electromagnetic wave and microwave technology, specifically relating to a frequency selective surface structure. Background Technology

[0002] A frequency selective surface (FSS) is a one-dimensional or two-dimensional periodic array structure composed of a large number of identical metal patch units or aperture units on a metal screen. It exhibits band-stop or band-pass filtering characteristics for electromagnetic waves of different frequencies. The filtering characteristics of the frequency selective surface make it widely used in many fields such as electromagnetic stealth, radar communication, electromagnetic shielding, and electromagnetic compatibility.

[0003] A frequency selective surface (FSS) is essentially a spatially structured filter. Unlike ordinary filters, its frequency response depends not only on its structural parameters but also significantly on the incident angle, polarization, and operating frequency of the electromagnetic wave. Theoretically, a FSS is an infinitely large periodic array structure, relying primarily on the interaction between its elements to achieve its filtering characteristics. A sufficient number of periodic elements must be arranged within a finite space to simulate an infinitely large periodic structure and achieve ideal filtering characteristics. However, in practical applications, FSSs are often limited by their structural size; too few periodic elements cannot maintain the characteristics of an infinitely large period. The resonant wavelength of a FSS is an integer multiple of its element size. By reducing the element size, more elements can be arranged within the same area, breaking the limitation of the operating wavelength and allowing the FSS to still achieve ideal filtering characteristics within a finite space. Therefore, designing miniaturized FSSs has significant practical value.

[0004] Miniaturization of frequency selective surfaces (FSSs) is an important direction in their development. Techniques such as unit cell curling, interdigital bonding, and coupling between inductive and capacitive surfaces are generally used to reduce the unit cell size, overcoming the limitation that unit cell size must match the resonant wavelength, thus achieving low-frequency filtering characteristics in a small structure. Unit cell curling and interdigital bonding techniques increase the effective electrical length by densely filling the units; however, a large number of grids or gaps can easily lead to interactions between unit cell resonant modes, severely impacting the filtering characteristics. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art or related art.

[0006] To this end, this application provides a frequency selective surface structure, including a first metal layer, a dielectric substrate, and a second metal layer. The dielectric substrate includes a first surface and a second surface, with the first surface and the second surface disposed opposite to each other. The first metal layer is disposed on the first surface, and the second metal layer is disposed on the second surface. A cross-shaped aperture unit and a connecting aperture and a zigzag aperture disposed on the circumferential side of the cross-shaped aperture unit are formed on the first metal layer. The cross-shaped aperture unit and the zigzag aperture are connected through the connecting aperture. The zigzag aperture extends in a periodic bending manner. The second metal layer includes square patch units.

[0007] Optionally, the cross aperture unit forms a cross aperture unit structure with the corresponding connecting aperture and the zigzag aperture. The cross aperture unit structure is a centrally symmetrical structure. The first metal layer includes multiple identical and periodically arranged cross aperture unit structures. The second metal layer includes multiple identical and periodically arranged square patch unit structures.

[0008] Optionally, the connecting aperture includes a first segment, a second segment, and a third segment connected in sequence. The first segment is set at an angle to the second segment, and the second segment is set at an angle to the third segment. The end of the first segment away from the second segment is connected to one end of the cross aperture unit, and the end of the third segment away from the second segment is connected to one end of the zigzag aperture.

[0009] Optionally, the first segment and the second segment are arranged perpendicularly to each other so that the whole formed by the first segment and the second segment has an L-shaped structure, the second segment and the third segment are arranged perpendicularly to each other so that the whole formed by the second segment and the third segment has an L-shaped structure, the first segment is perpendicularly connected to the cross aperture unit, and the third segment is perpendicularly connected to the zigzag aperture.

[0010] Optionally, the zigzag aperture extends in a periodic bend along a section from the second segment toward the cross aperture unit connected to the first segment. The zigzag aperture includes a fourth segment, a fifth segment, a sixth segment, a seventh segment, and an eighth segment that are vertically connected in sequence. The first segment, the third segment, the fifth segment, and the seventh segment extend in the same direction, as do the second segment, the fourth segment, the sixth segment, and the eighth segment.

[0011] Optionally, the third, fifth, and seventh segments have the same length, the fourth, sixth, and eighth segments have the same length, and each segment in the cross aperture unit, the first segment, the second segment, the third segment, the fourth segment, the fifth segment, the sixth segment, the seventh segment, and the eighth segment have the same width.

[0012] Optionally, the first metal layer includes an outer frame, the outer frame having a square annular structure, the side length of the outer frame being D, where D = 6.3 to 6.5 mm, and the width of a single side of the outer frame being g, where g = 0.1 to 0.3 mm;

[0013] The length of the first segment is l, where l = 2.7–2.9 mm;

[0014] The width of the second segment is s, where s = 0.3–0.5 mm;

[0015] The shortest interval between the third segment and the cross aperture unit, and the shortest interval between the seventh segment and the cross aperture unit, is w, where w = 0.2–0.4 mm.

[0016] Optionally, the dielectric substrate has a cubic structure, the second metal layer has a square structure, and the center point of the dielectric substrate and the center point of the second metal layer are located on the same normal line of the second metal layer.

[0017] Optionally, half of the spacing between adjacent square patch units on the second metal layer is e, where e = 0.1 to 0.3 mm.

[0018] Optionally, the vertical distance between the first metal layer and the second metal layer is h, where h = 0.2 mm to 2 mm.

[0019] Beneficial effects

[0020] The frequency selective surface structure provided in the embodiments of the present invention comprises a first metal layer and a second metal layer disposed on a dielectric substrate. The first metal layer has cross-shaped aperture units and connecting apertures and zigzag apertures disposed on the circumferential sides of the cross-shaped aperture units. The cross-shaped aperture units and the zigzag apertures are connected through the connecting apertures, and the zigzag apertures extend in a periodic bend. This design effectively increases the resonant length, reduces the resonant frequency, and achieves miniaturization of the frequency selective surface structure, while maintaining good filtering characteristics under large-angle electromagnetic wave incidence conditions. By loading square patch periodic units on the second metal layer, the frequency selectivity is further improved, achieving good out-of-band rejection characteristics. The frequency selective surface structure proposed in this embodiment is simple, has low insertion loss, good angular stability and polarization stability, and achieves highly selective bandpass filtering characteristics. Attached Figure Description

[0021] Figure 1 This is a three-dimensional structural schematic diagram of the frequency selective surface structure of the present invention;

[0022] Figure 2 This is a schematic diagram of the structure of the first metal layer of the present invention;

[0023] Figure 3 This is a schematic diagram showing the dimensional parameters of the first metal layer of the present invention;

[0024] Figure 4 This is a schematic diagram of the structure of the second metal layer of the present invention;

[0025] Figure 5 The transmission characteristics of the frequency-selective surface structure of the present invention when electromagnetic waves are incident perpendicularly in TE polarization mode;

[0026] Figure 6 The transmission characteristics of the frequency-selective surface structure of the present invention when electromagnetic waves are incident perpendicularly in TM polarization mode.

[0027] Figure 7 The transmission characteristics of the frequency-selective surface structure of the present invention under different incident angles of electromagnetic waves in TE polarization mode;

[0028] Figure 8 The transmission characteristics of the frequency-selective surface structure of the present invention under different incident angles in electromagnetic wave TM polarization mode are shown.

[0029] The reference numerals in the attached figures are as follows:

[0030] 1. First metal layer; 11. Outer frame; 121. First segment; 122. Second segment; 123. Third segment; 124. Fourth segment; 125. Fifth segment; 126. Sixth segment; 127. Seventh segment; 128. Eighth segment; 13. Cross-shaped aperture unit; 2. Dielectric substrate; 3. Second metal layer. Detailed Implementation

[0031] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0032] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0033] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0034] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0035] See also Figures 1 to 4 As shown, according to an embodiment of this application, a frequency selective surface structure includes a first metal layer 1, a dielectric substrate 2, and a second metal layer 3. The dielectric substrate 2 includes a first surface and a second surface, which are disposed opposite to each other. The first metal layer 1 is disposed on the first surface, and the second metal layer 3 is disposed on the second surface. A cross-shaped aperture unit 13 is formed on the first metal layer 1, and a connecting aperture and a zigzag aperture are disposed on the circumferential side of the cross-shaped aperture unit 13. The cross-shaped aperture unit 13 and the zigzag aperture are connected through the connecting aperture. The zigzag aperture extends in a periodic bending manner. The second metal layer 3 includes a square patch unit.

[0036] By setting a first metal layer 1 and a second metal layer 3 on the dielectric substrate 2, the first metal layer 1 is formed with a cross-shaped aperture unit 13 and a connecting aperture and a zigzag aperture disposed on the circumferential side of the cross-shaped aperture unit 13. The cross-shaped aperture unit 13 and the zigzag aperture are connected through the connecting aperture, and the zigzag aperture extends in a periodic bending manner, which effectively increases the resonance length and improves the miniaturization. It still has good filtering characteristics under the condition of large-angle incident electromagnetic waves, and has good angular stability and polarization stability, realizing stable bandpass filtering characteristics. By loading a square patch unit on the second metal layer 3, the frequency selectivity is improved by utilizing the interlayer coupling effect with the first metal layer 1, and good out-of-band suppression characteristics are achieved.

[0037] The dielectric substrate 2 can be a cube structure. The first surface and the second surface are two opposing surfaces of the cube structure in the normal direction of the first surface or the normal direction of the second surface. Alternatively, the first surface and the second surface can be understood as two opposing surfaces of the cube structure.

[0038] The outer edge of the first metal layer 1 is disposed along the edge of the first surface.

[0039] Among them, the cross-shaped aperture unit 13 has a cross-shaped structure.

[0040] The circumferential side of the cross aperture element 13, that is, the circumferential side of the center point of the cross aperture element 13, can also be understood as the circumferential side of the central axis of the cross aperture element 13.

[0041] Among them, the zigzag aperture extends in a periodic bend, that is, the zigzag aperture bends in a certain periodic pattern and extends in one direction as a whole.

[0042] Specifically, in this embodiment, the cross aperture unit 13 is divided into four segments around its own center point, and the entire zigzag aperture extends toward one segment of the cross aperture unit 13 that is connected to the zigzag aperture itself.

[0043] The frequency-selective surface structure comprises multiple periodically arranged periodic units; that is, multiple periodic units arranged periodically form the frequency-selective surface structure. Figure 1 A three-dimensional structural schematic diagram of a periodic unit is shown, wherein each periodic unit includes a cross aperture unit 13 and a connecting aperture and a broken line aperture disposed on the circumferential side corresponding to the cross aperture unit 13.

[0044] The cross aperture unit 13, together with the corresponding connecting aperture and the zigzag aperture, forms a cross aperture unit structure. The cross aperture unit structure is a centrally symmetrical structure. The first metal layer 1 includes multiple identical and periodically arranged cross aperture unit structures. The second metal layer 3 includes multiple identical and periodically arranged square patch unit structures, which improves the polarization stability of the frequency selective surface structure and maintains stable filtering characteristics for electromagnetic waves with different polarization modes.

[0045] The axis of symmetry of the cross-shaped aperture unit structure is the normal to the first surface passing through the center point of the first metal layer 1.

[0046] Among them, such as Figure 1 As shown, a periodic unit includes a cross aperture unit 13. The number of connecting apertures and polygonal apertures in the periodic unit is even. One connecting aperture and one polygonal aperture form a group. All groups of connecting apertures and polygonal apertures are symmetrically arranged with the center of the cross aperture unit 13 as the axis of symmetry.

[0047] Specifically, in this embodiment, there are four connecting apertures and four broken-line apertures in one periodic unit, forming four groups with one-to-one correspondence between the connecting apertures and the broken-line apertures. Each group of connecting apertures and broken-line apertures is connected to a segment of the cross-aperture unit 13 in the periodic unit. The channel formed by the four groups of connecting apertures and broken-line apertures and the cross-aperture unit 13 in the periodic unit is a centrally symmetrical structure with the center of the cross-aperture unit 13 as the axis of symmetry.

[0048] Specifically, such as Figure 2As shown, one set of connecting apertures and zigzag apertures is positioned to the upper left of the center point of the cross aperture unit 13. Another set of connecting apertures and zigzag apertures is positioned to the upper right of the center point of the cross aperture unit 13. A third set of connecting apertures and zigzag apertures is positioned to the lower left of the center point of the cross aperture unit 13. Finally, a fourth set of connecting apertures and zigzag apertures is positioned to the lower right of the center point of the cross aperture unit 13.

[0049] The connecting aperture includes a first segment 121, a second segment 122, and a third segment 123 connected in sequence. The first segment 121 and the second segment 122 are set at an angle, and the second segment 122 and the third segment 123 are set at an angle. The end of the first segment 121 away from the second segment 122 is connected to one end of the cross aperture unit 13, and the end of the third segment 123 away from the second segment 122 is connected to one end of the zigzag aperture.

[0050] The first segment 121 and the second segment 122 are set at an angle that is neither 0° nor 180°.

[0051] The second segment 122 and the third segment 123 are set at an angle that is neither 0° nor 180°.

[0052] The first segment 121 is perpendicular to the second segment 122, so that the overall structure formed by the first segment 121 and the second segment 122 is L-shaped. The second segment 122 is perpendicular to the third segment 123, so that the overall structure formed by the second segment 122 and the third segment 123 is L-shaped. The first segment 121 is perpendicularly connected to the cross-shaped aperture unit 13, and the third segment 123 is perpendicularly connected to the zigzag aperture. By setting the connecting aperture and the zigzag aperture as a zigzag structure, the electrical size is further increased, the resonant frequency is reduced, the miniaturization of the frequency selective surface structure is achieved, and the angular stability of the filtering characteristics is improved.

[0053] In this section, the end of the first segment 121 that is away from the cross aperture unit 13 is perpendicularly connected to the end of the second segment 122 that is away from the cross aperture unit 13, forming an L-shape.

[0054] The connecting aperture and the broken line aperture are arranged on the circumferential side of the cross aperture unit 13. Each set of connecting aperture and broken line aperture is located between two segments of the cross aperture unit 13 in the circumferential direction. The second segment 122 extends parallel to one segment of the cross aperture unit 13 connected to the first segment 121, and the second segment 122 extends perpendicularly toward one segment of the adjacent cross aperture unit 13.

[0055] One end of the third segment 123 is perpendicularly connected to the end of the second segment 122 that is away from the first segment 121, and the other end of the third segment 123 extends perpendicularly toward a section of the cross-shaped aperture 13 that is connected to the first segment 121.

[0056] Specifically, the first section 121 and the third section 123 extend in the same direction, that is, both the first section 121 and the third section 123 extend perpendicularly towards one section of the cross-aperture unit 13 connected to the first section 121.

[0057] Specifically, the overall shape formed by the first section 121, the second section 122, and the third section 123 is generally a U-shaped structure. Among the two parallel sides of this U-shaped structure, the length of one side is greater than that of the other side.

[0058] The folded-line aperture extends periodically in a bent manner along the direction from the second section 122 towards one section of the cross-aperture unit 13 connected to the first section 121. The folded-line aperture includes a fourth section 124, a fifth section 125, a sixth section 126, a seventh section 127, and an eighth section 128 that are vertically connected in sequence. The first section 121, the third section 123, the fifth section 125, and the seventh section 127 extend in the same direction, and the second section 122, the fourth section 124, the sixth section 126, and the eighth section 128 extend in the same direction, further increasing the electrical size, raising the resonant wavelength, and lowering the resonant frequency.

[0059] Among them, the overall folded-line aperture extends periodically in a bent manner along the direction perpendicular to one section of the cross-aperture unit 13 connected to the first section 121 from the second section 122.

[0060] Among them, the fourth section 124, the fifth section 125, the sixth section 126, the seventh section 127, and the eighth section 128 are vertically connected in sequence.

[0061] Specifically, the fifth section 125 and the seventh section 127 are arranged in parallel. The fifth section 125 is perpendicularly connected to the ends of the fourth section 124 and the sixth section 126 far from the third section 123 respectively, and the seventh section 127 is perpendicularly connected to the ends of the sixth section 126 and the eighth section 128 far from the fifth section 125 respectively, so that the overall shape formed by the fourth section 124, the fifth section 125, the sixth section 126, the seventh section 127, and the eighth section 128 is generally a "ji" shape.

[0062] The third section 123, the fifth section 125, and the seventh section 127 have the same length. The fourth section 124, the sixth section 126, and the eighth section 128 have the same length. The widths of each section in the cross-aperture unit 13, the first section 121, the second section 122, the third section 123, the fourth section 124, the fifth section 125, the sixth section 126, the seventh section 127, and the eighth section 128 are the same.

[0063] Among them, the lengths of the fourth section 124, the sixth section 126, and the eighth section 128 are all greater than the lengths of the third section 123, the fifth section 125, and the seventh section 127.

[0064] Among them, the widths of each segment in the cross aperture unit 13, the first segment 121, the second segment 122, the third segment 123, the fourth segment 124, the fifth segment 125, the sixth segment 126, the seventh segment 127 and the eighth segment 128 are the same, that is, the widths of all apertures are the same.

[0065] Among them, each segment of the cross aperture unit 13, the first segment 121, the second segment 122, the third segment 123, the fourth segment 124, the fifth segment 125, the sixth segment 126, the seventh segment 127 and the eighth segment 128 are all elongated strips, with the length direction being the extension direction and the width direction being the direction parallel to the first surface and perpendicular to the length direction.

[0066] The first metal layer 1 includes an outer frame 11, which has a square structure and a side length of D, where D = 6.3–6.5 mm. The width of a single side of the outer frame 11 is g, where g = 0.1–0.3 mm. The length of the first segment 121 is l, where l = 2.7–2.9 mm. The width of the second segment 122 is s, where s = 0.3–0.5 mm. The shortest interval between the third segment 123 and the cross-shaped aperture unit 13, and the shortest interval between the seventh segment 127 and the cross-shaped aperture unit 13, are w, where w = 0.2–0.4 mm.

[0067] Specifically, in this embodiment, D = 6.4 mm, g = 0.2 mm, w = 0.3 mm, s = 0.4 mm, and l = 2.8 mm.

[0068] The width of a single side of the outer frame 11 is half the distance between adjacent periodic units.

[0069] The first metal layer 1 includes an outer frame 11 and an inner extension bending portion. One end of the inner extension bending portion is connected to the inner edge of the outer frame 11, and the other end of the inner extension bending portion bends and extends into the area enclosed by the outer frame 11, and bends at a right angle during the extension process, dividing the outer frame 11 into internal spaces to form a cross aperture unit 13, a connecting aperture, and a broken line aperture.

[0070] The outer frame 11 encloses a square closed-loop structure.

[0071] The outer frame 11 and the inner extension bending part are an integral structure.

[0072] Specifically, the first metal layer 1 can be disposed on the first surface using photolithography or printed circuit board fabrication processes. The second metal layer 3 can be disposed on the second surface using photolithography or printed circuit board fabrication processes.

[0073] The outer frame 11 and its inner extension bending portion within its range form a group, and the first metal layer 1 includes multiple groups of outer frames 11 and their inner extension bending portions within their range. Each group of outer frames 11 and its inner extension bending portion within its range is disposed on the first surface, and the outer edge of the outer frame 11 is connected to the outer edge of the adjacent outer frame 11.

[0074] The dielectric substrate 2 has a cubic structure, and the second metal layer 3 has a square structure. The center point of the dielectric substrate 2 and the center point of the second metal layer 3 are located on the same normal line of the second metal layer 3.

[0075] In each periodic unit, the dielectric substrate 2 has a cubic structure, the second metal layer 3 in each periodic unit has a square structure, and the center point of the dielectric substrate 2 in each periodic unit and the center point of the second metal layer 3 in that periodic unit are on the same normal line of the second metal layer 3.

[0076] The spacing between adjacent square patch units of the second metal layer 3 is half of e, where e = 0.1 to 0.3 mm.

[0077] Specifically, in this embodiment, e = 0.2 mm.

[0078] The vertical distance between the first metal layer 1 and the second metal layer 3 is h, where h = 0.2 mm to 2 mm.

[0079] The vertical distance between the first metal layer 1 and the second metal layer 3 is also the thickness of the dielectric substrate 2.

[0080] Specifically, in this embodiment, h = 0.5 mm.

[0081] To verify the performance of the frequency selective surface structure in this embodiment, simulation analysis was performed to analyze the filtering characteristics of the frequency selective surface structure under different polarization modes and incident angles.

[0082] Figure 5 The transmission characteristic curves of the frequency selective surface structure of this embodiment when electromagnetic waves are vertically incident in TE polarization are given. It can be seen that the frequency selective surface structure of this embodiment forms a resonant frequency band in the C-band, with a center resonant frequency of 4.02 GHz, a -3 dB bandwidth of 0.72 GHz (3.63 GHz to 4.35 GHz), and an in-band insertion loss of only 0.15 dB. The frequency selective surface structure of this embodiment has extremely strong frequency selectivity near 4.02 GHz, and the out-of-band suppression in the frequency ranges below 2.80 GHz and above 4.96 GHz is below -10 dB, which has a strong suppression effect on out-of-band signals.

[0083] Figure 6The transmission characteristic curves of the frequency selective surface structure of this embodiment when electromagnetic waves are vertically incident in TM polarization mode are given. The frequency selective surface structure of this embodiment has a resonant band around 4.02 GHz, a -3 dB bandwidth of 0.70 GHz to 3.60 GHz to 4.30 GHz, and an in-band insertion loss of only 0.14 dB. The frequency selective surface structure of this embodiment forms a highly selective bandpass filtering characteristic around 4.02 GHz, and the out-of-band rejection in the frequency ranges below 2.82 GHz and above 4.89 GHz is below -10 dB.

[0084] contrast Figure 5 and Figure 6 The transmission wave characteristic curve shows that the frequency selective surface structure in this embodiment has C-band bandpass filtering performance under TE polarization and TM polarization, and the structure has excellent polarization stability.

[0085] Furthermore, in order to study the angular stability of the frequency selective surface structure in this embodiment, electromagnetic waves with TE polarization and TM polarization were incident at incident angles of 0°, 30°, 45° and 60°, respectively, and the filtering characteristics of the frequency selective surface structure in this embodiment were obtained. Figure 7 This embodiment describes the transmission characteristics of electromagnetic waves incident at different incident angles using the frequency-selective surface structure in TE polarization. Figure 8 This describes the transmission characteristics of electromagnetic waves incident at different incident angles when the frequency-selective surface structure of this embodiment is TM polarized.

[0086] from Figure 7 It can be seen that under TE polarization, when the incident angle of the electromagnetic wave increases from 0° to 60°, the frequency selective surface structure of this embodiment has stable resonance characteristics at 4.02GHz, and the center resonant frequency shift is very small, only 0.04GHz, which has excellent transmission characteristics and anti-interference ability.

[0087] from Figure 8 As can be seen, under TM polarization, when electromagnetic waves are incident at different angles, the frequency selective surface structure of this embodiment still has stable filtering characteristics at 4.02 GHz, and the center resonant frequency shift is still very small, only 0.03 GHz, which has excellent transmission characteristics and anti-interference ability.

[0088] comprehensive Figure 7 and Figure 8 As can be seen, the frequency selective surface structure of this embodiment always has stable bandpass filtering characteristics in the C-band when electromagnetic waves under TE polarization and TM polarization are incident at different angles, and the resonant frequency remains stable, exhibiting excellent angular stability.

[0089] The first metal layer 1 and the second metal layer 3 are made of gold, copper, silver or aluminum, and can achieve good out-of-band suppression characteristics through the interlayer coupling effect of the first metal layer 1 and the second metal layer 3.

[0090] The second metal layer 3 is composed of periodically arranged square metal patch units.

[0091] Specifically, in this embodiment, the first metal layer 1 and the second metal layer 3 are made of copper.

[0092] The dielectric substrate 2 is made of fiber or resin material or a composite material of fiber and resin.

[0093] Specifically, in this embodiment, the dielectric substrate 2 is made of F4B polytetrafluoroethylene, with a relative permittivity ε r =2.65, dielectric loss tangent tanδ =0.002, thickness h =0.5mm.

[0094] Specifically, in this embodiment, the unit size of the first metal layer 1 and the second metal layer 3 is 6.4mm × 6.4mm. 6.4mm is equivalent to 0.086 times the resonant wavelength, which meets the trend of miniaturization.

[0095] Frequency selective surface structures can be used in satellite communication equipment, radar antenna equipment, and other devices.

[0096] Specifically, frequency selective surface structures can be used in radar radomes and sub-reflector antennas, such as in C-band radar radomes.

[0097] An embodiment of the present invention provides a frequency selective surface structure and a radar communication system, wherein the frequency selective surface structure has the following beneficial effects:

[0098] 1. The frequency selective surface structure in this embodiment has extremely strong filtering characteristics near 4.02GHz and good out-of-band suppression performance, which can ensure that the communication signals in the corresponding frequency band are not interfered with by other frequency signals.

[0099] 2. In this embodiment, the frequency selection surface structure is a centrally symmetric structure, which has excellent polarization stability and maintains a stable resonant frequency when electromagnetic waves are incident under different polarizations.

[0100] 3. The frequency-selective surface structure in this embodiment has excellent angular stability. When electromagnetic waves are incident at angles of 0° to 60°, the resonant frequency remains stable with very small deviation.

[0101] 4. In this embodiment, the frequency selective surface structure utilizes the interlayer coupling effect of the first metal layer 1 and the second metal layer 3 to improve the frequency selectivity characteristics and has good out-of-band suppression characteristics.

[0102] 5. The frequency-selective surface structure in this embodiment has a unit spacing of only 6.4mm × 6.4mm. 6.4mm is only 0.086 times the resonant wavelength. The structure is simple and easy to manufacture.

[0103] 6. The frequency-selective surface structure in this embodiment has an insertion loss of only 0.15dB, which enables it to achieve high in-band transmittance.

[0104] 7. The frequency selective surface structure in this embodiment can be applied to C-band radar radomes.

[0105] It will be readily understood by those skilled in the art that the aforementioned advantageous methods can be freely combined and superimposed without conflict.

[0106] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application. The above are merely preferred embodiments of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the protection scope of this application.

Claims

1. A frequency-selective surface structure, characterized in that, The device includes a first metal layer (1), a dielectric substrate (2), and a second metal layer (3). The dielectric substrate (2) includes a first surface and a second surface, which are disposed opposite to each other. The first metal layer (1) is disposed on the first surface, and the second metal layer (3) is disposed on the second surface. A cross-shaped aperture unit (13) and a connecting aperture and a zigzag aperture disposed on the circumferential side of the cross-shaped aperture unit (13) are formed on the first metal layer (1). The cross-shaped aperture unit (13) and the zigzag aperture are connected through the connecting aperture. The zigzag aperture extends in a periodic bending manner. The second metal layer (3) includes a square patch unit. The cross aperture unit (13) forms a cross aperture unit structure with the corresponding connecting aperture and the zigzag aperture. The cross aperture unit structure is a centrally symmetrical structure. The first metal layer (1) includes multiple identical and periodically arranged cross aperture unit structures. The second metal layer (3) includes multiple identical and periodically arranged square patch unit structures. The connecting aperture includes a first segment (121), a second segment (122), and a third segment (123) connected in sequence. The first segment (121) is set at an angle to the second segment (122), and the second segment (122) is set at an angle to the third segment (123). The end of the first segment (121) away from the second segment (122) is connected to one end of the cross aperture unit (13), and the end of the third segment (123) away from the second segment (122) is connected to one end of the zigzag aperture. The first segment (121) and the second segment (122) are arranged perpendicularly to each other so that the whole formed by the first segment (121) and the second segment (122) is L-shaped. The second segment (122) and the third segment (123) are arranged perpendicularly to each other so that the whole formed by the second segment (122) and the third segment (123) is L-shaped. The first segment (121) is perpendicularly connected to the cross aperture unit (13), and the third segment (123) is perpendicularly connected to the zigzag aperture. The zigzag aperture extends periodically along a section from the second segment (122) toward the cross aperture unit (13) connected to the first segment (121). The zigzag aperture includes a fourth segment (124), a fifth segment (125), a sixth segment (126), a seventh segment (127), and an eighth segment (128) that are connected vertically in sequence. The first segment (121), the third segment (123), the fifth segment (125), and the seventh segment (127) extend in the same direction. The second segment (122), the fourth segment (124), the sixth segment (126), and the eighth segment (128) extend in the same direction.

2. The frequency selective surface structure according to claim 1, characterized in that, The third segment (123), the fifth segment (125), and the seventh segment (127) have the same length. The fourth segment (124), the sixth segment (126), and the eighth segment (128) have the same length. The widths of each segment in the cross aperture unit (13), the first segment (121), the second segment (122), the third segment (123), the fourth segment (124), the fifth segment (125), the sixth segment (126), the seventh segment (127), and the eighth segment (128) are the same.

3. The frequency-selective surface structure according to claim 2, characterized in that, The first metal layer (1) includes an outer frame (11), which has a square annular structure and a side length of [missing information]. D , D =6.3~6.5mm, the width of a single side of the outer frame (11) is g , g =0.1~0.3mm; The length of the first segment (121) is l , l =2.7~2.9mm; The width of the second segment (122) is s , s =0.3~0.5mm; The shortest interval between the third segment (123) and the cross aperture unit (13) and the shortest interval between the seventh segment (127) and the cross aperture unit (13) are: w , w =0.2~0.4mm.

4. The frequency selective surface structure according to claim 1, characterized in that, The dielectric substrate (2) has a cubic structure, and the second metal layer (3) has a square structure. The center point of the dielectric substrate (2) and the center point of the second metal layer (3) are on the same normal line of the second metal layer (3).

5. The frequency-selective surface structure according to claim 1, characterized in that, Half of the spacing between adjacent square patch units on the second metal layer (3) is e , e =0.1~0.3mm.

6. The frequency selective surface structure according to claim 1, characterized in that, The vertical distance between the first metal layer (1) and the second metal layer (3) is h , h =0.2mm~2mm.

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