Frequency selective surface unit, array, structure and antenna

Abstract

The invention discloses a frequency selective surface unit, an array, a structure and an antenna. The frequency selective surface unit comprises a dielectric plate; the first metal patch comprises a plurality of first extension parts connected with the central part of the dielectric plate, and the plurality of first extension parts extend towards the periphery from the central part of the dielectric plate; the second metal patch comprises a plurality of second extension parts, each second extension part is connected to the tail end of one first extension part, the plurality of second extension parts extend along the edge of the dielectric plate, and the second extension parts are arranged at intervals; wherein the first metal patch and the second metal patch form an LC equivalent resonance circuit. According to the frequency selective surface unit, the array, the structure and the antenna provided by the invention, the frequency response range can be expanded, multi-band electromagnetic waves can be effectively processed, and the performance of the frequency selective surface unit in the aspects of working band, bandwidth coverage, angle stability and the like can be improved.

Description

Technical Field

[0001] The present invention belongs to the field of communication technology, and in particular relates to a frequency selective surface unit, array, structure and antenna. Background Art

[0002] With the continuous development of communication technology, the coverage requirements of 4G and 5G networks are increasing, and the deployment of base station antennas has become a key link in the communication infrastructure. In order to achieve the same tower and height coverage of 4G and 5G base station antennas, active and passive integrated base station antennas with fusion characteristics have been widely used and promoted. The co-tower deployment of 4G and 5G not only saves infrastructure costs, but also effectively improves the quality and stability of network coverage. However, the existing passive and active base station antenna deployment scheme still has certain technical bottlenecks and limitations.

[0003] The current mainstream deployment scheme of active and passive integrated base station antennas is usually to place the passive antenna module and the active antenna module in front and behind. By using the frequency selective surface (FSS), the reflection of the passive antenna module and the transmission of the active antenna module are achieved. However, one of the main problems faced by this design method is that due to the different operating frequency bands of active and passive antennas, the transmission bandwidth of the existing FSS is relatively narrow, resulting in insufficient frequency adaptability. In practical applications, 4G networks usually operate in the frequency band of 698-960MHz, while 5G networks mainly cover higher frequency bands such as 3400-3800MHz and 2496-2690MHz. The collaborative work of passive antennas and active antenna modules in these frequency ranges is limited by the frequency selectivity of FSS. The existing FSS structure is difficult to provide sufficient transmission and reflection performance in multiple frequency bands at the same time, resulting in large transmission losses and affecting the transmission quality of signals.

[0004] Therefore, it is necessary to provide a new solution to the above technical problems. Summary of the invention

[0005] The object of the present invention is to provide a frequency selective surface unit, array, structure and antenna, which can broaden the operating frequency range and adapt to the multi-band requirements of 4G and 5G.

[0006] To achieve the above purpose, the technical solution provided by the present invention is as follows:

[0007] In the first aspect, the present invention provides a frequency selective surface unit, which includes: a dielectric plate; a first metal patch, including a plurality of first extension portions connected to the central portion of the dielectric plate, and the plurality of first extension portions extend from the central portion of the dielectric plate toward the surrounding areas; a second metal patch, including a plurality of second extension portions, each of the second extension portions is respectively connected to the end of one of the first extension portions, and the plurality of second extension portions extend along the edge of the dielectric plate, and the second extension portions are spaced apart from each other; wherein the first metal patch and the second metal patch constitute an LC equivalent resonant circuit.

[0008] In one or more embodiments, the first extension portion is formed of a meandering metal wire that can form an inductor.

[0009] In one or more embodiments, the first extension portion is serpentine or spiral.

[0010] In one or more embodiments, the second extension portion is formed of an elongated metal wire, and a terminal end of the first extension portion is connected to a middle portion of the second extension portion.

[0011] In one or more embodiments, the dielectric plate is provided with a first metallized via hole that passes through the front and back sides of the dielectric plate, the first extension portion includes a first metal wire provided on the front side of the dielectric plate and a second metal wire provided on the back side of the dielectric plate, and the first metal wire and the second metal wire are connected through the first metallized via hole.

[0012] In one or more embodiments, the first metal line and the second metal line are connected to each other in a serpentine shape along the normal direction of the dielectric plate, with their projections on a plane perpendicular to the normal of the dielectric plate.

[0013] In one or more embodiments, the dielectric plate is provided with a second metallized via that passes through the front and back sides of the dielectric plate, the second extension portion includes a third metal wire provided on the front side of the dielectric plate and a fourth metal wire provided on the back side of the dielectric plate, and the third metal wire and the fourth metal wire are connected through the second metallized via.

[0014] In one or more embodiments, projections of the third metal line and the fourth metal line along the normal direction of the dielectric plate on a plane perpendicular to the normal of the dielectric plate overlap with each other.

[0015] In one or more embodiments, the first metal patch includes four first extension portions respectively extending toward four sides of the dielectric plate.

[0016] In one or more embodiments, the four first extension portions are centrally symmetrically arranged.

[0017] In one or more embodiments, two of the four first extension portions are disposed on the front side of the dielectric plate, and the other two first extension portions are disposed on the back side of the dielectric plate.

[0018] In one or more embodiments, the first extension portion disposed on the front side of the dielectric plate and the first extension portion disposed on the back side of the dielectric plate are connected via a metallized via hole located in the center of the dielectric plate.

[0019] In one or more embodiments, the second extension portion connected to the first extension portion provided on the front surface of the dielectric plate extends to the front surface of an adjacent frequency selective surface unit, and the second extension portion connected to the first extension portion provided on the back surface of the dielectric plate extends to the back surface of an adjacent frequency selective surface unit.

[0020] In one or more embodiments, the second extension portion extending to the front side of the adjacent frequency selective surface unit and the second extension portion on the back side of the adjacent frequency selective surface unit have projections on the normal direction of the dielectric plate that overlap with each other; the second extension portion extending to the back side of the adjacent frequency selective surface unit and the second extension portion on the front side of the adjacent frequency selective surface unit have projections on the normal direction of the dielectric plate that overlap with each other.

[0021] In one or more embodiments, the dielectric plate is square, and the second metal patch includes four second extension portions adjacent to an edge of the dielectric plate and extending along four sides of the dielectric plate.

[0022] In a second aspect, the present invention provides a frequency selective surface array, which comprises a plurality of periodically arranged frequency selective surface units as described above, wherein the plurality of frequency selective surface units constitute an equivalent resonant circuit of cascaded series LC and parallel C.

[0023] In a third aspect, the present invention provides a multi-layer frequency selective surface structure, characterized in that it comprises a plurality of layers of the frequency selective surface units described above.

[0024] In one or more embodiments, a spacing dielectric layer is provided between the frequency selective surface units of adjacent layers, and the thickness of the spacing dielectric layer is one quarter of the central wavelength of the multi-layer frequency selective surface structure.

[0025] In a fourth aspect, the present invention provides an antenna comprising the aforementioned frequency selective surface array or multi-layer frequency selective surface structure.

[0026] Compared with the prior art, the frequency selective surface unit, array, structure and antenna provided by the present invention form an LC equivalent resonant circuit inside the unit and construct a cascaded series LC and parallel C resonant network through series capacitors provided by adjacent units; this design can improve the frequency response range, can effectively process multi-band electromagnetic waves, and improve the performance of the frequency selective surface unit in terms of operating frequency band, bandwidth coverage and angle stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 A schematic diagram of the structure of a frequency selective surface unit in one embodiment of the present invention;

[0029] Figure 2 A schematic diagram of the structure of a frequency selective surface array according to an embodiment of the present invention;

[0030] Figure 3 for Figure 2 The stopband performance simulation diagram of the frequency selective surface array shown;

[0031] Figure 4 for Figure 2 The passband performance simulation diagram of the frequency selective surface array shown;

[0032] Figure 5 It is a structural schematic diagram of a frequency selective surface array in another embodiment of the present invention;

[0033] Figure 6 A schematic diagram of the structure of a frequency selective surface array in yet another embodiment of the present invention;

[0034] Figure 7 for Figure 6 The stopband performance simulation diagram of the frequency selective surface array shown;

[0035] Figure 8 for Figure 6 The passband performance simulation diagram of the frequency selective surface array shown;

[0036] Fig. 9 A schematic structural diagram of a multi-layer frequency selective surface structure in another embodiment of the present invention;

[0037] Fig.10 for Fig. 9 Equivalent circuit diagram of the multilayer frequency selective surface structure shown. DETAILED DESCRIPTION

[0038] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0039] Unless explicitly stated otherwise, throughout the specification and claims, the term “comprise” or variations such as “include” or “comprising”, etc., will be understood to include the stated elements or components but not to exclude other elements or components.

[0040] The frequency selective surface unit of the present invention is intended to solve the limitations of the existing communication base station antenna system in terms of multi-band adaptability and frequency selection performance, especially in the application scenario where 4G and 5G base station antennas share the same tower and height for coverage. The existing technology has many deficiencies in terms of frequency bandwidth, angle stability and multi-band compatibility. Through the analysis of the prior art, the inventors found that the existing frequency selective surface (FSS) structure cannot meet the needs of the new generation of communication technology in terms of bandwidth coverage and angle adaptability. Especially in the scenario where active and passive antennas are deployed in an integrated manner, the existing FSS design has problems such as narrow transmission frequency bandwidth, poor angle stability, and poor multi-band compatibility, which limits the performance and adaptability of the antenna system.

[0041] Based on this, the present invention proposes a new frequency selective surface unit, the design idea of ​​which is to achieve wide adaptability to different frequency bands and improve the stability of the signal under multi-angle incidence conditions through optimized metal patch structure and coupling design. The present invention broadens the operating frequency band by constructing a resonant structure of inductance and capacitance of an optimized frequency selective surface unit, and effectively improves the frequency response stability of the antenna at different angles through structural design and routing optimization, thereby achieving multi-band coverage and multi-angle stability.

[0042] Please refer to Figure 1 As shown, the frequency selective surface unit in one embodiment of the present invention includes a dielectric plate 130 , a first metal patch 110 and a second metal patch 120 .

[0043] The first metal patch 110 includes a plurality of first extensions 111 connected to the central portion of the dielectric plate 130, and the plurality of first extensions 111 extend from the central portion of the dielectric plate 130 toward the surroundings. The second metal patch includes a plurality of second extensions 121, each second extension 121 is respectively connected to the end of a first extension 111, and the plurality of second extensions 121 extend along the edge of the dielectric plate 130, and the second extensions 121 are spaced apart from each other. The first metal patch 110 and the second metal patch 120 form a parallel LC equivalent resonant circuit, thereby realizing selective regulation of the frequency of electromagnetic waves.

[0044] The dielectric plate 130, as the carrier component of the entire frequency selective surface unit, provides a stable bearing platform for supporting the distribution and extension of the metal patch. The dielectric plate 130 can not only carry the aforementioned metal patch, but also affect the conduction, transmission and reflection of electromagnetic waves on its surface through its material properties. Since the propagation speed and impedance of electromagnetic waves in the dielectric material are directly related to its dielectric constant, a suitable dielectric material can be selected according to actual design requirements. The thickness of the dielectric plate 130 is preferably within 0.762 mm. It serves as a carrier for the metal elements in structure, and helps the FSS work in the required low-frequency band in terms of performance; and a thinner dielectric plate 130 is conducive to reducing the passband loss of the FSS and improving the passband transmission rate.

[0045] The first metal patch 110 mainly plays the role of forming inductance in the frequency selective surface unit. The first metal patch 110 extends from the central position of the dielectric plate 130 to the surrounding of the dielectric plate 130 through a plurality of first extension portions 111. This extended layout not only increases the surface area of ​​the metal patch, but also extends the path of electromagnetic wave transmission, thereby increasing the equivalent inductance.

[0046] Connected to the first metal patch 110 is a second metal patch 120 located at the edge of the dielectric plate 130. The second metal patch 120 cooperates with the first metal patch to form an inductor on the one hand, and is used to form a capacitor on the other hand. The second metal patch 120 has a plurality of second extensions 121, which are respectively connected to the ends of the first extension 111 and are distributed along the edge of the dielectric plate 130. Since the second extensions 121 are spaced apart and do not contact each other and there are gaps, these gaps constitute the key elements of the capacitor. By adjusting the spacing between the second extensions 121, the capacitance value can be controlled. The extension design of the second metal patch 120 at the edge not only enhances the electromagnetic wave reflection performance of the FSS unit to the edge area, but also realizes the effective regulation of electromagnetic waves in different directions through the gaps, thereby achieving a precise frequency selection effect.

[0047] The first metal patch 110 and the second metal patch 120 are connected to each other and together form an LC equivalent resonant circuit. The mutual inductance between the first extensions 111, between the second extensions 121, and between the first extension 111 and the second extension 121 forms a parallel capacitor. The combination of the inductor and the capacitor in the resonant circuit can accurately control the resonant frequency of the electromagnetic wave by adjusting its specific geometric parameters, so that the frequency selective surface unit can adapt to different frequency band requirements.

[0048] In an exemplary embodiment, the first extension portion 111 is composed of a meandering metal wire that can form an inductor. Compared with a straight metal trace, the meandering structure can not only extend the transmission path of the electromagnetic wave on the limited surface of the dielectric plate 130, but also increase the interaction time between the metal wire and the electromagnetic wave. By increasing the length of this trace, the equivalent inductance (L value) of the frequency selective surface unit is increased. This design utilizes the conductivity of the metal and guides the current to flow along a tortuous path to generate strong electromagnetic induction, thereby forming an inductance effect. The size of the inductance value directly affects the resonant frequency of the FSS. Increasing the inductance can reduce the resonant frequency of the system, making it suitable for electromagnetic wave control needs in lower frequency bands.

[0049] Each bend in the meandering line changes the direction of the current, making the magnetic field distribution in the current path more complex, thereby strengthening the coupling effect between the electromagnetic wave and the FSS structure. Compared with straight metal wires, meandering metal wires can more flexibly control the resonant behavior of electromagnetic waves, allowing the FSS unit to show good selectivity in electromagnetic wave transmission in different frequency bands.

[0050] In addition to increasing the inductance value, the meandering metal wire also plays an important role in frequency tuning. By adjusting the length, width and bend density of the metal wire, the distribution of current in the trace can be accurately controlled, affecting the resonant frequency of the FSS unit. The design of the meandering trace can broaden the range of frequency response without increasing the volume of the structure. Therefore, according to the actual application requirements, the geometric parameters of the meandering metal wire can be changed to achieve the adjustment of electromagnetic waves in different frequency bands.

[0051] The meandering metal wire structure also has a certain anti-interference ability. Since the flow direction of the current in the meandering path is constantly changing, the FSS unit can maintain a relatively stable frequency response when dealing with electromagnetic waves incident from different directions. Even at different incident angles, the meandering line can still effectively guide the propagation of electromagnetic waves on the metal surface and maintain the resonant performance of the FSS unit.

[0052] Preferably, the first extension portion 111 is serpentine or spiral. The serpentine structure can be a metal wire arranged in a plurality of tortuous paths, which extends along the surface of the dielectric plate 130 in a winding manner. The spiral structure further improves the density and flow efficiency of the current through the spiral arrangement. The spiral design is conducive to achieving a longer current path in a compact area, similar to the effect of a coil. This structure can more effectively generate inductance, so that the electromagnetic wave produces a strong resonance effect in the frequency selective surface unit.

[0053] In an exemplary embodiment, the second extension portion 121 is formed of a thin and long metal wire, and the end of the first extension portion 111 is connected to the middle of the second extension portion 121. Compared with the winding or spiral shape of the first extension portion 111, the second extension portion 121 extends along the edge of the dielectric plate 130 in a thin and long line, the main purpose of which is to provide a stable capacitor path.

[0054] The thin and long metal wires enable electromagnetic waves to propagate effectively in the edge area and form an electric field between the metal wires. This design not only helps to form capacitance, but also achieves response to different frequency bands through distributed metal wires, so as to maintain stable electromagnetic wave transmission and reflection effects within a wide bandwidth.

[0055] The end of the first extension 111 is connected to the middle of the second extension 121, so that the metal trace parts are combined with each other, thereby forming a series inductor-capacitor network. The first extension 111 is mainly responsible for forming the inductor, and the second extension 121 provides the edge-related capacitance effect. By connecting the end of the first extension 111 to the middle of the second extension 121, the inductor and the capacitor can be combined to work together to construct a series LC equivalent resonant circuit.

[0056] Please refer to Figure 2 FIG. 2 is a schematic diagram of a frequency selective surface array 20 in an embodiment of the present invention. The frequency selective surface array 20 includes a plurality of frequency selective surface units 200 arranged in an array. Each frequency selective surface unit 200 includes a square dielectric plate 230 as a supporting platform for the entire frequency selective surface unit 200, and a first metal patch 210 and a second metal patch 220 are distributed on the dielectric plate 230.

[0057] The first metal patch 210 includes four first serpentine extensions 211, and extends in four directions toward the dielectric plate 230 in a centrally symmetrical manner. The serpentine design hereby serves to extend the current path and increase the inductance. The centrally symmetrical layout further optimizes the distribution of the electromagnetic field, and can exhibit good angular stability at different incident angles. This symmetrical design ensures that the current can be evenly distributed on each extension, and there will be no phenomenon of excessive current concentration or uneven electromagnetic field distribution due to structural asymmetry.

[0058] The second metal patch 220 is located at the edge of the dielectric plate 230 and extends along four sides to form four slender second extensions 221. The second extensions 221 are arranged adjacent to the edge of the dielectric plate, and there is a certain gap between the second extensions 221 of two adjacent frequency selective surface units 200, which can provide a series capacitance effect. The size of these series capacitors is determined by the geometric properties (such as length and width) of the second extensions 221 and the gaps between them. By optimizing these geometric parameters, the capacitance value of the system can be adjusted, and then the overall resonant frequency of the system can be regulated. The slender design of the second extensions 221 can not only enhance the edge reflection effect of the system on electromagnetic waves, but also make the capacitance effect of the entire unit more uniform and stable by being distributed along the edge of the dielectric plate 230.

[0059] The end of the first extension part 211 is connected to the middle of the second extension part 221. Through this connection, the inductance effect of the first extension part 211 and the capacitance effect of the second extension part 221 are combined to form a parallel LC equivalent resonant circuit. This circuit can accurately select the frequency of the electromagnetic wave, and by adjusting the values ​​of the inductance and capacitance, it can achieve the regulation of electromagnetic waves in different frequency bands. Specifically, the end of the first extension part 211 guides the current from the center to the edge and is connected to the middle of the second extension part 221. This design ensures that the electromagnetic field is evenly distributed on the dielectric plate 230, forming an effective current loop, thereby enhancing the electromagnetic coupling effect.

[0060] Figure 3 and Figure 4 for Figure 2 The stopband and passband performance simulation diagrams of the frequency selective surface array are shown in Figure 1. Figure 3 and Figure 4 It can be seen that the frequency selective surface array achieves a -10 dB passband of 1.5 GHz to 2.7 GHz while ensuring a -10 dB stopband of 0.612 to 0.96, and the relative passband bandwidth is 57.1%.

[0061] Please refer to Figure 5 FIG. 5 is a schematic diagram of a frequency selective surface array 50 in an embodiment of the present invention. The frequency selective surface array 50 includes a plurality of frequency selective surface units 500 arranged in an array. Each frequency selective surface unit 500 includes a square dielectric plate 530 as a supporting platform for the entire frequency selective surface unit 500, and a first metal patch 510 and a second metal patch 520 are distributed on the dielectric plate 530. The first metal patch 510 has a first extension portion 511 extending toward the four sides of the dielectric plate 530, and the second metal patch 520 has a second extension portion 521.

[0062] exist Figure 5In the illustrated embodiment, the first extension portion 511 includes a first metal line 512 disposed on the front side of the dielectric plate 530 and a second metal line 513 disposed on the back side of the dielectric plate 530. The dielectric plate 530 is provided with a first metallized via 540 that passes through the front side and the back side thereof, forming a path for current conduction, connecting the first metal line 512 disposed on the front side of the dielectric plate and the second metal line 513 disposed on the back side.

[0063] With this structure, the length of the metal wire can be extended in a limited space, thereby enhancing the inductance, and the current can flow freely between the front and back sides of the dielectric plate 530, thereby enhancing the electromagnetic coupling effect of the entire frequency selective surface unit. By providing the first metallized via 540 on the dielectric plate 530, the space on both sides of the dielectric plate is effectively utilized, so that the electromagnetic waves can interact between the front and back sides, extending the path of the current, thereby enhancing the inductance effect.

[0064] The first metal wire 512 and the second metal wire 513 are respectively located on the front and back of the dielectric plate, and they are interconnected through the first metallized via 540 to form a three-dimensional current loop. This three-dimensional structure of the metal wire design allows the current to flow freely on both sides, thereby improving the strength of the inductance (L value) and widening the bandwidth. In the traditional two-dimensional design, the current is limited to flowing on one surface of the dielectric plate, and the electromagnetic coupling effect is relatively limited. By connecting the metal wires on both sides through metallized vias, the current can switch between the two surfaces, forming a more complex current path, thereby increasing the inductance effect of the system. This increase in inductance directly improves the frequency selection capability of the frequency selective surface unit, enabling it to resonate at a lower frequency.

[0065] The advantage of this double-sided connection structure is that it can significantly extend the current transmission path and improve the overall inductance without increasing the physical size of the system. At the same time, by using both sides of the dielectric plate, the system achieves higher space utilization, allowing the frequency selective surface unit to have stronger frequency response capabilities in a smaller size.

[0066] Specifically, the first metal wire 512 and the second metal wire 513 are connected to each other in a serpentine shape along the normal direction of the dielectric plate 530, and their projections on a plane perpendicular to the normal of the dielectric plate 530. The serpentine structure, as a geometric form for optimizing the current path, has a significant effect in electromagnetic regulation. The serpentine design extends the total length of the metal wire through multiple bends and turns, making the current flow path more complex and tortuous. Each bending point causes the direction of the current to change, thereby increasing the distribution area and inductance of the electromagnetic field. When the first metal wire 512 and the second metal wire 513 are projected in the normal direction to form a serpentine structure, the current can not only flow along the surface of the dielectric plate, but also guide the current to switch in the vertical direction at the bend, further enhancing the overall electromagnetic coupling effect.

[0067] Please refer to Figure 5 As shown, the dielectric plate 530 is provided with a second metallized via 550 that passes through the front and back sides of the dielectric plate 530 , and the second extension portion 521 includes a third metal wire 522 provided on the front side of the dielectric plate and a fourth metal wire 523 provided on the back side of the dielectric plate 530 , and the third metal wire 522 and the fourth metal wire 523 are connected via the second metallized via 550 .

[0068] The second metallized via 550 is a conductive channel that runs through the dielectric plate 530. The inside of the via is metallized to ensure that the current can flow with low impedance, connecting the metal wires on the front and back of the dielectric plate 530. Through this design, the current can flow on both sides of the dielectric plate 530, which not only extends the current path, but also effectively increases the inductance value of the system, thereby enhancing the control capability of electromagnetic waves.

[0069] The third metal line 522 is located on the front side of the dielectric plate 530, and is mainly responsible for forming a capacitive effect in the system and constructing a resonant circuit together with the fourth metal line 523. The third metal line 523 is connected to the fourth metal line 524 through a via, thereby forming a system with a wider electromagnetic field distribution and tighter coupling.

[0070] Specifically, the projections of the third metal wire 522 and the fourth metal wire 523 on a plane perpendicular to the normal of the dielectric plate 530 overlap each other along the normal direction of the dielectric plate 530. The design of overlapping projections is to optimize the conduction path of the current by accurately aligning the geometric positions of the metal wires on both sides, ensuring that a consistent electromagnetic response can be generated at different frequencies. When the third metal wire 522 and the fourth metal wire 523 are strictly aligned in the normal direction, the propagation paths of the electromagnetic waves on both sides will be more consistent, thereby enhancing the electromagnetic field distribution of the system.

[0071] Please refer to Figure 6FIG. 1 is a schematic diagram of a frequency selective surface array 60 in one embodiment of the present invention. The frequency selective surface array 60 includes a plurality of frequency selective surface units 600 arranged in an array. Each frequency selective surface unit 600 includes a square dielectric plate 630 as a supporting platform for the entire frequency selective surface unit 600, and a first metal patch 610 and a second metal patch 620 are distributed on the dielectric plate 630.

[0072] exist Figure 6 In the illustrated embodiment, the first metal patch 610 includes four first extension portions 611 extending toward the four sides of the dielectric plate 630. Among them, two first extension portions 611 of the four first extension portions 611 are arranged on the front side of the dielectric plate 630, and the other two first extension portions 611 are arranged on the back side of the dielectric plate 630. The first extension portions 611 on the front and back sides of the dielectric plate 630 can be connected through the connection wires 612 arranged on the front and back sides, and the connection wires on the front and back sides can be connected through metallized vias.

[0073] The main metal wire portion of the first extension 611 adopts an Archimedean spiral structure. The Archimedean spiral is a spiral metal trace, which is characterized by equal intervals between each turn and the direction of the current in the trace being consistent. This design can significantly reduce the total length of the trace while maintaining the inductance value (L value), thereby optimizing the performance of the frequency selective surface unit, especially in terms of angle stability and component integration density per unit area.

[0074] The Archimedean spiral structure has a high space utilization rate. Compared with the serpentine routing, the spiral structure can extend the current path in a more compact way in a limited space. Through this geometric design, the direction of the current flowing in the routing is always consistent, avoiding the uneven distribution of the electromagnetic field caused by complex changes in the current direction. This feature not only improves the current flow efficiency, but also makes the inductance effect more uniform, ensuring that the frequency selective surface unit can operate stably under different working conditions.

[0075] Due to the compactness of the Archimedean spiral trace, it can achieve a longer current path in a smaller area, thereby increasing the inductance value while reducing the total length of the trace. This design can optimize the unit period, that is, integrate more frequency selective surface units (FSS units) without increasing the size of the component.

[0076] The consistency of the current direction in the trace is an important feature of the Archimedean spiral design. When the current flows along the spiral, its direction is always consistent, which avoids the loss and interference caused by the frequent changes in direction of the current in complex traces. With this feature, the current flows more efficiently in the trace, thereby enhancing the electromagnetic induction effect and improving the overall inductance value.

[0077] In addition, the Archimedean spiral design also significantly improves angular stability. Due to the symmetry and compactness of the spiral structure, the spiral can receive and respond uniformly regardless of the angle from which the electromagnetic wave is incident. This geometric symmetry ensures that the frequency selective surface unit maintains consistent electromagnetic wave selection performance under multi-angle incidence conditions, reducing frequency offset or response instability caused by changes in the incident angle.

[0078] Please refer to Figure 6 As shown, the second extension portion 621 connected to the first extension portion 611 disposed on the front side of the dielectric plate 630 extends to the front side of the adjacent frequency selective surface unit, and the second extension portion 621 connected to the first extension portion 611 disposed on the back side of the dielectric plate 630 extends to the back side of the adjacent frequency selective surface unit.

[0079] The second extension 621 on the front and back sides of the dielectric plate 630 forms an overlapping structure on the front and back sides of the dielectric plate 630 through the connection of adjacent units. This overlap not only increases the interaction between adjacent units, but also improves the electromagnetic wave coupling strength. Traditional designs may only rely on connections on a single plane, but through this extended overlap on both sides, the current can be evenly distributed on both sides, thereby achieving a higher electromagnetic effect. The overlapping design enables the electric field to have a stronger interaction between the front and back sides. This coupling not only optimizes the electric field distribution, but also significantly increases the series capacitance effect and improves the frequency selection performance.

[0080] Compared with the interdigital structure, this overlapping design also solves the problems that may occur in the interdigital structure. Although the interdigital structure can also increase capacitance, it is easy to produce resonance within the band, resulting in unnecessary interference and frequency response deviation. However, through the overlapping connection of the front and back second extensions 621, this design effectively avoids the defects of the interdigital structure. Especially in high-frequency applications, this design can provide a larger capacitance value while reducing the risk of resonance within the band, thereby ensuring that the system can maintain good performance within a wide frequency band. Moreover, this overlapping extension design simplifies the manufacturing process, reduces the difficulty and cost of processing, and can improve the consistency and reliability of processing.

[0081] Specifically, the projections of the second extension portion 621 extending to the front of the adjacent frequency selective surface unit and the second extension portion 621 on the back of the adjacent frequency selective surface unit in the normal direction of the dielectric plate 630 overlap with each other. The projections of the second extension portion 621 extending to the back of the adjacent frequency selective surface unit and the second extension portion 621 on the front of the adjacent frequency selective surface unit in the normal direction of the dielectric plate 630 overlap with each other.

[0082] The second extension portion 621 extending to the front of the adjacent frequency selective surface unit and the second extension portion 621 on the back of the adjacent frequency selective surface unit overlap in the normal direction of the dielectric plate 630. The second extension portion 621 extending to the back of the adjacent frequency selective surface unit and the second extension portion 621 on the front of the adjacent frequency selective surface unit overlap in the normal direction of the dielectric plate 630.

[0083] The design of overlapping projections of the second extension 621 on the front and back optimizes the current transmission path and the distribution of the electromagnetic field. The second extension 621 extends from the front of one unit to the front of the adjacent unit, and at the same time, the second extension 621 on the back also extends to the back of the adjacent unit accordingly. When these extensions on the front and back are projected and overlapped with each other in the normal direction, the current can be conducted with high consistency on both the front and back sides. This structural overlap creates a strong coupling effect between the electromagnetic waves on the front and back sides, thereby making the electric field more evenly distributed throughout the system, reducing current interference and electromagnetic wave losses during transmission.

[0084] Figure 7 and Figure 8 for Figure 6 The stopband and passband performance simulation diagrams of the frequency selective surface array are shown in Figure 1. Figure 7 and Figure 8 It can be seen that the frequency selective surface array achieves a -10dB passband of 2.1GHz to 4GHz while ensuring a -10dB stopband of 0.612 to 0.96, and the relative passband bandwidth reaches 62.3%.

[0085] The frequency selective surface array in the present invention can form a parallel LC equivalent resonant circuit inside the frequency selective surface unit, and provide series capacitance through adjacent frequency selective surface units, thereby forming a cascaded series LC and parallel C equivalent resonant circuit.

[0086] Please refer to Fig. 9 FIG. 1 is a schematic diagram of a multi-layer frequency selective surface structure in an embodiment of the present invention, wherein the multi-layer frequency selective surface structure 900 includes a plurality of layered frequency selective surface units 901. The routing of the frequency selective surface units 901 is arranged along the xy direction, and the layering direction is arranged along the z direction.

[0087] A spacing dielectric layer 902 is provided between adjacent layers of the frequency selective surface units 901 . The thickness of the spacing dielectric layer 902 is one quarter of the central wavelength of the multi-layer frequency selective surface structure 900 .

[0088] The routing of the frequency selective surface unit 901 is arranged on the xy plane, that is, the metal wire structure of the unit extends along the xy plane. The routing of each unit is responsible for generating local inductance effect and capacitance effect, thereby forming an independent LC equivalent resonant circuit. This design can effectively select the frequency of the incident electromagnetic wave, and by controlling the length, width and shape of the routing, the system's response to electromagnetic waves of different frequency bands can be accurately adjusted. In addition, the arrangement of the routing in the xy direction enables the system to handle electromagnetic waves incident at different angles, thereby enhancing angular stability.

[0089] The layer arrangement direction is arranged along the z direction, indicating that multiple frequency selective surface units 901 are arranged in a stacked manner. The frequency selective units of each layer are parallel to each other and arranged perpendicular to the z direction. This three-dimensional stacking design maximizes the space utilization and further broadens the frequency response range of the system through the interaction between layers. This vertical arrangement can effectively enhance the propagation path of electromagnetic waves in the vertical plane, allowing the system to more accurately control incident waves at different heights and angles.

[0090] A spacing dielectric layer 902 is provided between the frequency selective surface units 901 of adjacent layers, and the thickness of the spacing dielectric layer 902 is one quarter of the central wavelength of the multi-layer frequency selective surface structure 900. The spacing dielectric layer 902 not only serves as a physical separation, but also acts as a transmission line of one quarter of the wavelength. Since the thickness of the spacing dielectric layer 902 matches one quarter of the central wavelength, the transmission length of the electromagnetic wave in the spacing dielectric layer 902 can just form a complete waveform reflection when passing through each frequency selective surface unit, thereby generating a dual resonant frequency point and widening the passband and stopband bandwidth. The spacing dielectric layer 902 can be an air layer or a dielectric layer of other materials.

[0091] The equivalent circuit of the multilayer frequency selective surface structure 900 can be expressed as Fig.10 The equivalent circuit inside each frequency selective surface unit 901 can be represented as a parallel LC circuit. The inductance L is generated from the metal wiring in the unit, which provides a corresponding inductive reactance, thereby reducing the resonant frequency. At the same time, a parallel capacitor C2 is formed between the metal wires inside the unit, providing a reactance value matching the inductance, so that the system can resonate with electromagnetic waves of a specific frequency.

[0092] The series capacitor C1 is generated by the coupling between adjacent frequency selective surface units 901. Since adjacent units influence each other in the electromagnetic field, the system forms a capacitive effect between each unit through the close arrangement of the metal layer and the dielectric layer. This series capacitor expands the frequency response range, allowing different units to resonate together to form a wider frequency band response, while being able to better handle the transmission of high-frequency signals.

[0093] In addition, the role of the spacer dielectric layer 902 is reflected in the equivalent circuit as a quarter-wavelength transmission line, whose resistance is approximately the air impedance. This part not only enhances the overall electrical impedance matching capability of the system, but also enables the system to maintain a high resonance efficiency in a wider frequency band by extending the propagation path of the electromagnetic wave. The quarter-wavelength design of the spacer dielectric layer ensures that the reflection and transmission process of the electromagnetic wave between each layer unit can be seamlessly coordinated, further improving the working performance.

[0094] The present invention also provides an antenna, which can be applied to the field of wireless communication antennas such as 4G and 5G. The antenna includes the aforementioned frequency selective surface array or multi-layer frequency selective surface structure.

[0095] In summary, the frequency selective surface unit, array, structure and antenna provided by the present invention form a parallel LC equivalent resonant circuit inside the unit and construct a cascaded series LC and parallel C resonant network through the series capacitors provided by adjacent units; this design can improve the frequency response range, can effectively process multi-band electromagnetic waves, and improve the performance of the frequency selective surface unit in terms of operating frequency band, bandwidth coverage and angle stability.

[0096] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0097] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A frequency selective surface unit, characterized in that: include: Dielectric plate; A first metal patch includes a plurality of first extensions connected to the central portion of the dielectric plate, wherein the plurality of first extensions extend from the central portion of the dielectric plate toward surrounding areas; A second metal patch, comprising a plurality of second extensions, each of which is connected to a terminal end of one of the first extensions, the plurality of second extensions extending along the edge of the dielectric plate, and the second extensions being spaced apart from each other; The first metal patch and the second metal patch form an LC equivalent resonant circuit.

2. The frequency selective surface unit according to claim 1, characterized in that The first extension portion is formed of a meandering metal wire capable of forming an inductor.

3. The frequency selective surface unit according to claim 2, characterized in that: The first extension portion is in a serpentine or spiral shape.

4. The frequency selective surface unit according to claim 1, characterized in that: The second extension portion is formed by a thin and long metal wire, and the end of the first extension portion is connected to the middle portion of the second extension portion.

5. The frequency selective surface unit according to claim 1, characterized in that: The dielectric plate is provided with a first metallized via hole penetrating the front and back sides of the dielectric plate, the first extension portion includes a first metal wire provided on the front side of the dielectric plate and a second metal wire provided on the back side of the dielectric plate, and the first metal wire and the second metal wire are connected through the first metallized via hole.

6. The frequency selective surface unit according to claim 5, characterized in that: The projections of the first metal line and the second metal line on a plane perpendicular to the normal line of the dielectric plate are connected to each other in a serpentine shape along the normal line direction of the dielectric plate.

7. The frequency selective surface unit according to claim 1, characterized in that: The dielectric plate is provided with a second metallized via hole penetrating the front and back sides of the dielectric plate, the second extension portion includes a third metal wire provided on the front side of the dielectric plate and a fourth metal wire provided on the back side of the dielectric plate, and the third metal wire and the fourth metal wire are connected through the second metallized via hole.

8. The frequency selective surface unit according to claim 7, characterized in that: The projections of the third metal line and the fourth metal line along the normal direction of the dielectric plate on a plane perpendicular to the normal of the dielectric plate overlap with each other.

9. The frequency selective surface unit according to claim 1, characterized in that: The first metal patch includes four first extension parts respectively extending toward the four sides of the dielectric plate.

10. The frequency selective surface unit according to claim 9, characterized in that: The four first extension portions are centrally symmetrically arranged.

11. The frequency selective surface unit according to claim 9, characterized in that: Two of the four first extensions are arranged on the front side of the dielectric plate, and the other two first extensions are arranged on the back side of the dielectric plate.

12. The frequency selective surface unit according to claim 11, characterized in that: The first extension portion arranged on the front side of the dielectric plate and the first extension portion arranged on the back side of the dielectric plate are connected through a metallized via hole located in the center of the dielectric plate.

13. The frequency selective surface unit according to claim 12, characterized in that: The second extension part connected to the first extension part arranged on the front side of the dielectric plate extends to the front side of the adjacent frequency selective surface unit, and the second extension part connected to the first extension part arranged on the back side of the dielectric plate extends to the back side of the adjacent frequency selective surface unit.

14. The frequency selective surface unit according to claim 13, characterized in that: The projections of the second extension portion extending to the front of the adjacent frequency selective surface unit and the second extension portion on the back of the adjacent frequency selective surface unit in the normal direction of the dielectric plate overlap with each other; The projections of the second extension portion extending to the back side of the adjacent frequency selective surface unit and the second extension portion on the front side of the adjacent frequency selective surface unit in the normal direction of the dielectric plate overlap with each other.

15. The frequency selective surface unit according to claim 1, characterized in that: The dielectric plate is in a square shape, and the second metal patch includes four second extension portions which are adjacent to the edge of the dielectric plate and extend along four sides of the dielectric plate.

16. A frequency selective surface array, characterized in that: The method comprises a plurality of periodically arranged frequency selective surface units according to any one of claims 1 to 15, wherein the plurality of frequency selective surface units constitute an equivalent resonant circuit of cascaded series LC and parallel C.

17. A multi-layer frequency selective surface structure, characterized in that: A frequency selective surface unit according to any one of claims 1 to 15 comprising a plurality of layers.

18. The multi-layer frequency selective surface structure according to claim 17, characterized in that: A spacing dielectric layer is provided between the frequency selective surface units of adjacent layers, and the thickness of the spacing dielectric layer is one quarter of the central wavelength of the multi-layer frequency selective surface structure.

19. An antenna, characterized in that: The frequency selective surface array comprising claim 16; Or comprising the multi-layer frequency selective surface structure according to any one of claims 17 and 18.

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