Miniaturized multilayer ultra-wideband millimeter wave frequency selective surface

Abstract

The invention provides a miniaturized multilayer ultra-wideband millimeter wave frequency selective surface, and relates to the technical field of frequency selective surfaces, the miniaturized multilayer ultra-wideband millimeter wave frequency selective surface comprises a first metal patch layer, a first dielectric layer, a second metal patch layer, a second dielectric layer, a third metal patch layer and a third dielectric layer which are stacked in sequence, the first metal patch layer comprises a plurality of concave parts, each concave part is arranged on each side of the first metal patch layer, the second metal patch layer comprises a first sub-patch and a second sub-patch, the centers of the first sub-patch and the second sub-patch coincide, and the third metal patch layer comprises a plurality of third sub-patches which are annularly arranged at equal intervals. According to the invention, the angle stability of the frequency selective surface is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of frequency selective surfaces, and in particular to a miniaturized multi-layer ultra-wideband millimeter-wave frequency selective surface. Background Art

[0002] A frequency selective surface (FSS) is a periodic surface that selectively transmits electromagnetic waves and can be used as a spatial filter. It has unique transmission, reflection, and absorption characteristics for electromagnetic waves of selected frequencies and has no special effect on electromagnetic waves outside the selected frequencies. It consists of a dielectric layer and a metal layer, and the metal layer is composed of metal sheets or conductive materials to form a periodic structure. Frequency selective surfaces are widely used in fields such as antenna manufacturing, radome design, filters, electromagnetic absorbers, and electromagnetic shielding devices, and can greatly improve the transmission and shielding performance of communication devices.

[0003] Chinese Patent with Publication No. CN112290225B discloses a large-angle broadband frequency selective surface, which includes a first dielectric substrate, a first metal structure array layer, a second dielectric substrate, a second metal structure array layer, a third dielectric substrate, a third metal structure array layer, and a fourth dielectric substrate stacked in sequence from bottom to top; the first metal structure array layer, the second metal structure array layer, and the third metal structure array layer are all composed of discrete metal patches arranged periodically. However, the frequency range corresponding to the transition band on both sides of the passband in the above solution is often relatively wide, and its angular stability is poor. Therefore, it is very necessary to provide a miniaturized multi-layer ultra-wideband millimeter-wave frequency selective surface to improve the angular stability of the frequency selective surface. Summary of the Invention

[0004] In view of this, the present invention proposes a miniaturized multi-layer ultra-wideband millimeter-wave frequency selective surface. Through the design of multi-layer metal patches, efficient frequency selection in the millimeter-wave band is achieved. The different geometric shapes and arrangement methods of each layer of metal patches further optimize the filtering performance of the frequency selective surface and improve the angular stability of the frequency selective surface through interlayer coupling effects.

[0005] The present invention provides a miniaturized multi-layer ultra-wideband millimeter-wave frequency selective surface, which includes a first metal patch layer, a first dielectric layer, a second metal patch layer, a second dielectric layer, a third metal patch layer, and a third dielectric layer stacked in sequence. The first metal patch layer has a plurality of concave portions, and each concave portion is disposed on each side edge of the first metal patch layer. The second metal patch layer includes a first sub-patch and a second sub-patch, and the centers of the first sub-patch and the second sub-patch coincide. The third metal patch layer includes a plurality of third sub-patches arranged in equally spaced rings.

[0006] Based on the above technical solutions, preferably, the first metal patch layer has four side edges of equal length, the ratio of the width of the concave portion to the side length of the first metal patch layer is 1:12, the ratio of the length of the concave portion to the side length of the first metal patch layer is 1:4, and the ratio of the width of the concave portion to the length of the concave portion is 1:4.

[0007] Based on the above technical solutions, preferably, the first sub-patch is a metal square loop patch, the second sub-patch is disposed inside the first sub-patch and at the central position of the first sub-patch, the second sub-patch is provided with a through hole, the through hole is located at the central position of the second sub-patch, and the cross-sectional shape of the through hole is cross-shaped.

[0008] More preferably, the ratio of the length of the second sub-patch to the length of the first sub-patch is 1:5, and the ratio of the horizontal axis length of the through hole to the length of the first sub-patch is 31:250.

[0009] More preferably, a plurality of the third sub-patches are arranged in a central annular array along the third metal patch layer.

[0010] More preferably, the third sub-patch includes a metal circular ring patch and a cross-shaped patch, and the center of the circular ring metal patch coincides with the center of the cross-shaped patch.

[0011] More preferably, the ratio of the ring width of the metal circular ring patch to the diameter of the metal circular ring patch is 1:8, and the ratio of the horizontal axis length of the cross-shaped patch to the diameter of the metal circular ring patch is 17:40.

[0012] More preferably, the thicknesses of the first metal patch layer, the second metal patch layer, and the third metal patch layer are all 0.3 - 0.5 μm.

[0013] More preferably, the thickness of the first dielectric layer is 0.65 - 0.75 mm, the thickness of the second dielectric layer is 0.5 - 0.6 mm, and the thickness of the third dielectric layer is 0.45 - 0.55 mm.

[0014] More preferably, the first dielectric layer, the second dielectric layer, and the third dielectric layer are all float glass, and the relative dielectric constants of the first dielectric layer, the second dielectric layer, and the third dielectric layer are 6 - 6.5.

[0015] The miniaturized multi-layer ultra-wideband millimeter-wave frequency selective surface provided by the present invention has the following beneficial effects compared with the prior art:

[0016] (1) The efficient frequency selection in the millimeter-wave band is achieved through the design of multi-layer metal patches, which can cover a wider frequency range to meet the requirements of ultra-wideband communication. The concave design of the first metal patch layer enhances the resonance characteristics of electromagnetic waves. The center coincidence design of the second sub-patch optimizes the electromagnetic coupling. The equally spaced circular patches in the third layer further improve the accuracy of frequency selection. Such multi-layer synergistic effects effectively improve the selectivity while reducing the insertion loss, ensuring the efficiency of signal transmission. At the same time, the geometric designs of the concave part, sub-patch, and circular patch make the metal patch structure of each layer compact, reducing the overall size, and making it suitable for miniaturized devices and highly integrated application scenarios. The different geometric shapes and arrangements of the metal patches in each layer further optimize the filtering performance of the frequency selective surface and enhance the angular stability of the frequency selective surface through inter-layer coupling effects.

[0017] (2) By arranging multiple third sub-patches in a central circular array to form a periodic structure, the resonance characteristics of electromagnetic waves are enhanced. And the center coincidence design of the metal circular patch and the cross-shaped patch further optimizes the transmission path of electromagnetic waves through the coupling effect, improving the accuracy of the resonance frequency. At the same time, the ratio of the ring width to the diameter of the circular patch is 1:8, and the ratio of the horizontal axis length of the cross-shaped patch to the diameter of the circular patch is 17:40. This enables the third metal patch layer to precisely control the resonance frequency of electromagnetic waves, thereby achieving high-selectivity passband and stopband responses. Description of the Drawings

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0019] Figure 1 Structural schematic diagram of the miniaturized multi-layer ultra-wideband millimeter-wave frequency selective surface provided by the present invention;

[0020] Figure 2 Unit structure diagram of the first metal patch layer provided by the present invention;

[0021] Figure 3 Unit structure diagram of the second metal patch layer provided by the present invention;

[0022] Figure 4 Unit structure diagram of the third metal patch layer provided by the present invention;

[0023] Figure 5 Simulation result diagram of the S11 and S21 response curves provided by the present invention;

[0024] Figure 6 This is the simulation result diagram of the insertion loss response curve at different incident angles under TE polarization provided by the present invention;

[0025] Figure 7 This is the simulation result diagram of the insertion loss response curve at different incident angles under TM polarization provided by the present invention.

[0026] Explanation of reference numerals: 1. First metal patch layer; 2. First dielectric layer; 3. Second metal patch layer; 4. Second dielectric layer; 5. Third metal patch layer; 6. Third dielectric layer. Detailed implementation manners

[0027] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0028] As Figure 1 shown, the present invention provides a miniaturized multi-layer ultra-wideband millimeter-wave frequency selective surface, which includes a first metal patch layer 1, a first dielectric layer 2, a second metal patch layer 3, a second dielectric layer 4, a third metal patch layer 5, and a third dielectric layer 6 stacked in sequence. The first metal patch layer 1 has a plurality of concave portions, and each concave portion is disposed on each side edge of the first metal patch layer 1. The first metal patch layer 1 has four side edges with equal lengths. The ratio of the width of the concave portion to the side length of the first metal patch layer 1 is 1:12, the ratio of the length of the concave portion to the side length of the first metal patch layer 1 is 1:4, and the ratio of the width of the concave portion to the length of the concave portion is 1:4.

[0029] In this embodiment, the design of the concave portion changes the equivalent circuit characteristics of the metal patch, increases the distribution of capacitance and inductance, thereby enhancing the resonance characteristics of electromagnetic waves. This optimization helps to improve the filtering performance of the frequency selective surface, especially the selectivity in the millimeter-wave band. The geometric ratio design of the concave portion enables the first metal patch layer 1 to more precisely control the transmission and reflection characteristics of electromagnetic waves, thereby achieving higher passband and stopband selectivity and meeting the requirements of ultra-wideband frequency selection. And the design of the concave portion effectively reduces the equivalent size of the metal patch while maintaining good electromagnetic performance. This design makes the size of the frequency selective surface unit smaller (such as 2.5×2.5 mm), which is suitable for miniaturized and highly integrated devices.

[0030] Furthermore, the presence of the concave portion increases the structural complexity of the metal patch, broadens the frequency ranges of the passband and stopband. Combining with the design of other metal patch layers, a broadband response with a -3dB passband (10.51 - 18.53 GHz) and a -10dB stopband (19.73 - 49.76 GHz) can be achieved. And the symmetric distribution design of the concave portion enables the first metal patch layer 1 to maintain a stable electromagnetic response at different incident angles, enhancing the angular stability of the frequency selective surface. At the same time, the geometric design of the concave portion is simple and regular, facilitating implementation through mature manufacturing processes, reducing the production difficulty and cost, while ensuring the repeatability and consistency of the structure.

[0031] The second metal patch layer 3 includes a first sub-patch and a second sub-patch. The centers of the first sub-patch and the second sub-patch coincide. The first sub-patch is a metal square loop patch. The second sub-patch is disposed within the first sub-patch and at the central position of the first sub-patch. The second sub-patch is provided with a through hole. The through hole is located at the central position of the second sub-patch, and the cross-sectional shape of the through hole is cross-shaped. The ratio of the length of the second sub-patch to the length of the first sub-patch is 1:5, and the ratio of the horizontal axis length of the through hole to the length of the first sub-patch is 31:250.

[0032] In this embodiment, the dual-patch design of the second metal patch layer 3, that is, the combination of the square loop and the central rectangular patch, forms a complex equivalent circuit model through interlayer coupling, that is, a parallel combination of an inductor and a capacitor, thereby enhancing the resonant characteristics of electromagnetic waves. The central cross-shaped through hole further increases the distribution path of electromagnetic waves, optimizes the transmission and reflection characteristics of electromagnetic waves, and improves the filtering performance of the frequency selective surface. The ratio of the size of the second sub-patch to the first sub-patch is optimized, enabling this layer structure to precisely control the resonant frequency of electromagnetic waves, thereby achieving efficient selection in the millimeter wave band. The specific ratio of the horizontal axis length of the cross-shaped through hole to the length of the first sub-patch further refines the regulation ability of frequency selection and improves the selectivity of the passband and stopband.

[0033] Furthermore, the central cross-shaped through-hole design of the second sub-patch increases the structural complexity and broadens the passband and stopband ranges of the frequency selective surface. Combining with the designs of other layers, a broadband response with a -3dB passband (10.51 - 18.53 GHz) and a -10dB stopband (19.73 - 49.76 GHz) can be achieved. The second sub-patch is nested within the first sub-patch, and the size ratio is optimized, making the layer structure compact and efficient, reducing the size of the overall frequency selective surface unit, and meeting the requirements of miniaturization and high integration. The design of the central cross-shaped through-hole has symmetry, enabling the second metal patch layer 3 to maintain consistent electromagnetic responses under different polarization states, enhancing the polarization consistency of the frequency selective surface. The geometric design of the second metal patch layer 3 optimizes the distribution path of electromagnetic waves, enabling the frequency selective surface to maintain stable transmission and reflection characteristics within the incident angle range of 0° to 60°. Although the design of the second metal patch layer 3 is complex, its geometric shape is regular, facilitating implementation through mature coating processes, reducing the manufacturing difficulty and cost, while ensuring the repeatability and consistency of the structure.

[0034] The third metal patch layer 5 includes a plurality of third sub-patches arranged in an equally spaced circular pattern. The plurality of third sub-patches are arranged in a central circular array along the third metal patch layer 5. The third sub-patch includes a metal circular patch and a cross-shaped patch, and the center of the circular metal patch coincides with the center of the cross-shaped patch. The ratio of the width of the metal circular patch to its diameter is 1:8, and the ratio of the horizontal axis length of the cross-shaped patch to the diameter of the metal circular patch is 17:40.

[0035] In this embodiment, the plurality of third sub-patches are arranged in a central circular array to form a periodic structure, enhancing the resonant characteristics of electromagnetic waves, especially showing excellent frequency selection performance in the millimeter-wave band. The design with the centers of the metal circular patch and the cross-shaped patch coinciding further optimizes the transmission path of electromagnetic waves through the coupling effect, improving the accuracy of the resonant frequency. The ratio of the width of the circular patch to its diameter is 1:8, and the ratio of the horizontal axis length of the cross-shaped patch to the diameter of the circular patch is 17:40, enabling the third metal patch layer 5 to precisely control the resonant frequency of electromagnetic waves, thereby achieving a highly selective passband and stopband response.

[0036] Multiple sub-patches arranged in equal-spacing rings are periodically arranged, increasing the complexity of the structure, broadening the passband and stopband ranges of the frequency selective surface, and meeting the requirements of ultra-wideband applications. The combined design of the metal circular patch and the cross-shaped patch is compact, and the optimization of the ratio of the ring width to the diameter and the size of the cross-shaped patch enables the overall size of this layer structure to be reduced while maintaining high efficiency, making it suitable for miniaturized devices. The central coincidence design of the metal circular patch and the cross-shaped patch has high symmetry, enabling the third metal patch layer 5 to maintain consistent electromagnetic responses in different polarization states and enhancing the polarization consistency. The sub-patches arranged in equal-spacing rings through periodic structure design enable the frequency selective surface to maintain stable transmission and reflection characteristics within the incident angle range of 0° to 60°, adapting to complex electromagnetic environments.

[0037] The thicknesses of the first metal patch layer 1, the second metal patch layer 3, and the third metal patch layer 5 are all 0.3 - 0.5 μm. The thickness of the first dielectric layer 2 is 0.65 - 0.75 mm, the thickness of the second dielectric layer 4 is 0.5 - 0.6 mm, and the thickness of the third dielectric layer 6 is 0.45 - 0.55 mm. The first dielectric layer 2, the second dielectric layer 4, and the third dielectric layer 6 are all float glass, and the relative dielectric constants of the first dielectric layer 2, the second dielectric layer 4, and the third dielectric layer 6 are 6 - 6.5.

[0038] In this step, the selection of the metal layer thickness ensures good conductivity while avoiding material waste caused by excessive thickness and unstable electromagnetic performance caused by insufficient thickness. This thickness range can effectively support the transmission and reflection of electromagnetic waves in the millimeter wave band, enhancing the filtering performance of the frequency selective surface. At the same time, the design of different dielectric layer thicknesses is optimized to adjust the electromagnetic coupling strength between layers, ensuring the width and stability of the passband and stopband. Float glass with a relative dielectric constant of 6 - 6.5 can provide an appropriate electromagnetic wave transmission speed and energy storage capacity in the millimeter wave band, thereby achieving a broadband filtering effect. The combined design of dielectric layers with different thicknesses and metal patch layers can effectively suppress the influence of incident angle changes on the filtering performance, enhancing the angle stability, and float glass has good thermal stability and can maintain stable dielectric properties in high-temperature environments, thus ensuring the reliability and durability of the frequency selective surface in complex environments.

[0039] Efficient frequency selection in the millimeter-wave band is achieved through the design of multi-layer metal patches, which can cover a wider frequency range to meet the requirements of ultra-wideband communication. The concave design of the first metal patch layer 1 enhances the resonance characteristics of electromagnetic waves. The center coincidence design of the second-layer sub-patches optimizes electromagnetic coupling. The third-layer equally spaced annular patches further improve the accuracy of frequency selection. This multi-layer synergistic effect effectively improves selectivity while reducing insertion loss, ensuring the efficiency of signal transmission. At the same time, the geometric designs of the concave part, sub-patches, and annular patches make the metal patch structure of each layer compact, reducing the overall size, which is suitable for miniaturized devices and high-integration application scenarios. The different geometric shapes and arrangements of the metal patches in each layer further optimize the filtering performance of the frequency selective surface and enhance the angular stability of the frequency selective surface through inter-layer coupling effects.

[0040] In one example, the miniaturized multi-layer ultra-wideband millimeter-wave frequency selective surface includes a plurality of frequency selective surface units arranged periodically. The frequency selective surface units are composed of a dielectric substrate and a metal layer on the surface of the dielectric substrate. The metal layer has three layers, namely the first metal patch layer 1, the second metal patch layer 3, and the third metal patch layer 5. The first metal patch layer 1 is a solid metal square ring, and the basic metal square ring structure is bent. The second metal patch layer 3 includes a solid metal square ring plus a solid rectangular structure with a cross slit in the center. The third metal patch layer 5 includes four solid circular ring structures with a solid cross-shaped structure in the center of the rings. The first metal patch layer 1, the second metal patch layer 3, and the third metal patch layer 5 are aligned and placed. The dielectric between the metal layers is a transparent float soda-lime glass material, and the centers of each metal layer coincide with the center of the surface of the dielectric substrate.

[0041] Please refer to Figures 2 to 4, the length of the square loop on either side in the first metal patch layer 1 is L1 = 1.8 mm, the loop width of the first metal patch layer 1 is W1 = 0.15 mm, the length of the bent part of the square loop structure is L2 = L4 = 0.45 mm, the width of the bent part is L3 = 0.45 mm, L5 = 0.15 mm, and the equivalent circuit of the first metal patch layer 1 is a capacitor and an inductor in series. The length of the square loop on either side in the second metal patch layer 3 is L6 = 2.5 mm, the loop width of the second metal patch layer 3 is W2 = 0.2 mm, the length of the solid rectangular structure is L7 = 0.5 mm, and the cross - slit dimensions are L8 = 0.05 mm, L9 = 0.31 mm. The second metal patch layer 3 includes a solid metal square loop plus a solid rectangular structure, and its equivalent circuit is an inductor in parallel with a capacitor. The four circular - ring metal structures in the third metal patch layer 5 are centrosymmetrically arranged about the center of the third metal patch layer 5. The width of the four circular rings is all W3 = 0.15 mm, the radii of the circular rings are R1 = 0.6 mm, R2 = 0.45 mm respectively, and the cross - shaped dimensions are L10 = 0.05 mm, L11 = 0.51 mm. The equivalent circuit is a capacitor and an inductor in series.

[0042] The height of the first dielectric layer 2 attached with the first metal patch layer 1 and the second metal patch layer 3 is h1 = 0.7 mm, the height of the second dielectric layer 4 attached with the second metal patch layer 3 and the third metal patch layer 5 is h2 = 0.55 mm, and the height of the second dielectric layer 4 is h3 = 0.5 mm. The first metal patch layer 1, the second metal patch layer 3, and the third metal patch layer 5 are all made of gold - plated material, and the thickness is 0.3 - 0.5 μm. In this embodiment, copper with excellent conductivity and stable electromagnetic performance is selected as the material of the metal structure, and the copper plating process is used to plate copper on the float soda - lime glass dielectric substrate.

[0043] As Figure 5 shown, Figure 5It is a simulation result diagram of the response curves of return loss and insertion loss. The horizontal axis represents the frequency range of electromagnetic waves, from 0 GHz to 60 GHz. The vertical axis represents the value of the S parameter, in decibels (dB). The reflection coefficient S11 represents the proportion of the incident signal that is reflected back, and the transmission coefficient S21 represents the proportion of the incident signal that is transmitted after passing through the structure. In most frequency ranges, S11 is close to 0 dB, indicating strong reflection. At certain frequency points (such as near 10 GHz, 30 GHz, and 50 GHz), S11 shows a significant decrease, reaching below -10 dB, indicating weak reflection at these frequency points and that the signal is mainly transmitted or absorbed. Near 10 GHz, 30 GHz, and 50 GHz, the S21 curve reaches a lower value (close to -30 dB), indicating weak transmission at these frequency points and that the signal is mainly reflected or absorbed. In other frequency ranges, S21 is close to 0 dB, indicating strong signal transmission. In the frequency range where S21 is close to 0 dB, the signal transmission is strong, indicating that this is the passband of the frequency selective surface. In the frequency range where S21 drops below -10 dB, the signal transmission is weak, indicating that this is the stopband of the frequency selective surface. It can be understood that this structure exhibits obvious frequency selectivity near 10 GHz, 30 GHz, and 50 GHz and can effectively distinguish between the passband and the stopband.

[0044] As Figure 6 shown, Figure 6 it is a simulation result diagram of the insertion loss response curves at different incident angles under TE polarization. Figure 6 It contains multiple curves, corresponding to different incident angles (0°, 10°, 20°, 30°, 40°, 50°, 60°) respectively. The curves show periodic fluctuations in the entire frequency range. In the frequency range where the transmission coefficient is close to 0 dB, the signal transmission is strong, indicating that this is the passband of the frequency selective surface. In the frequency range where the transmission coefficient drops below -10 dB, the signal transmission is weak, indicating that this is the stopband of the frequency selective surface. The passband mainly appears near 10 GHz, 30 GHz, and 50 GHz, and the transmission coefficient is close to 0 dB, indicating strong signal transmission in these frequency ranges. The stopband appears near 20 GHz and 40 GHz, and the transmission coefficient drops below -30 dB, indicating weak signal transmission in these frequency ranges. In the incident angle range from 0° to 60°, the change trends of the curves are basically the same, and the positions of the passband and the stopband do not shift significantly, indicating that this frequency selective surface has good angular stability. Even when the incident angle increases to 60°, the change amplitude of the transmission coefficient is small, indicating that this structure can maintain stable frequency selection performance in a wide incident angle range. This frequency selective surface exhibits obvious passband and stopband characteristics in the range from 10 GHz to 60 GHz and is suitable for ultra-wideband applications. In the incident angle range from 0° to 60°, the positions and performance of the passband and the stopband remain stable, adapting to complex electromagnetic environments.

[0045] Figure 7 This is the simulation result diagram of the insertion loss response curve at different incident angles under TM polarization provided by the present invention. Under TM polarization, the curve shows periodic fluctuations in the entire frequency range. The passbands also appear near 10 GHz, 30 GHz, and 50 GHz, and the transmission coefficient is close to 0 dB, indicating that the signal transmission is strong in these frequency ranges. The stopbands appear near 20 GHz and 40 GHz, and the transmission coefficient drops below -30 dB, indicating that the signal transmission is weak in these frequency ranges and is mainly reflected or absorbed. In the incident angle range from 0° to 60°, the change trends of each curve are basically the same, and the positions of the passband and stopband do not shift significantly, indicating that the frequency selective surface has good angular stability. Even when the incident angle increases to 60°, the change amplitude of the transmission coefficient is small, indicating that this structure can maintain stable frequency selective performance in a wide incident angle range.

[0046] In summary, for this miniaturized multi-layer ultra-wideband millimeter-wave frequency selective surface structure, the transmittance is greater than 90% at 10.51 - 18.53 GHz, covering the entire Ku band; the transmission coefficient is below -10 dB at 19.73 - 49.76 GHz, which can cover the K band, Ka band, and part of the U band. At the same time, it has good stability and polarization consistency in the incident angle range of 0 - 60°. According to the filtering characteristics of the frequency selective surface, the filtering effect can be achieved at different frequency bands. The unit size of the FSS is generally comparable to the wavelength of the incident electromagnetic wave. Factors such as the unit size of the FSS, the thickness of the metal layer, the shape of the metal layer structure, the properties of the dielectric material, and the thickness of the dielectric layer will all affect the filtering effect. It can be clearly seen that the -3 dB passband is located at 10.51 - 18.53 GHz, and the -10 dB stopband is located at 19.73 - 49.76 GHz. The relative bandwidths are 55.2% and 86.4% respectively, and it maintains good transmission and reflection characteristics in the incident angle range of 0 - 60°, achieving an excellent filtering effect, and having good polarization stability and angular stability.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A miniaturized multi-layer ultra-wideband millimeter-wave frequency selective surface, characterized in that: The invention comprises a first metal patch layer (1), a first dielectric layer (2), a second metal patch layer (3), a second dielectric layer (4), a third metal patch layer (5) and a third dielectric layer (6) which are stacked in sequence, wherein the first metal patch layer (1) has a plurality of concave portions, each of which is arranged on each side of the first metal patch layer (1); the second metal patch layer (3) comprises a first sub-patch and a second sub-patch, the first sub-patch and the second sub-patch have centers that coincide with each other; and the third metal patch layer (5) comprises a plurality of third sub-patch arranged in an annular manner at equal intervals.

2. The miniaturized multi-layer ultra-wideband millimeter-wave frequency selective surface according to claim 1, characterized in that: The first metal patch layer (1) has four sides of equal length, the ratio of the width of the inner recess to the length of the side of the first metal patch layer (1) is 1:12, the ratio of the length of the inner recess to the length of the side of the first metal patch layer (1) is 1:4, and the ratio of the width of the inner recess to the length of the inner recess is 1:

4.

3. The miniaturized multi-layer ultra-wideband millimeter-wave frequency selective surface according to claim 1, characterized in that: The first sub-patch is a metal square ring patch, the second sub-patch is arranged in the first sub-patch and located at the center of the first sub-patch, the second sub-patch is provided with a through hole, the through hole is located at the center of the second sub-patch, and the cross-sectional shape of the through hole is a cross.

4. The miniaturized multi-layer ultra-wideband millimeter-wave frequency selective surface according to claim 3, characterized in that: The ratio of the length of the second sub-patch to the length of the first sub-patch is 1:5, and the ratio of the horizontal axis length of the through hole to the length of the first sub-patch is 31:

250.

5. The miniaturized multi-layer ultra-wideband millimeter-wave frequency selective surface according to claim 1, characterized in that: The plurality of third sub-patches are arranged in a central annular array along the third metal patch layer (5).

6. The miniaturized multi-layer ultra-wideband millimeter-wave frequency selective surface according to claim 5, characterized in that: The third sub-patch includes a metal ring patch and a cross-shaped patch, and the center of the metal ring patch coincides with the center of the cross-shaped patch.

7. The miniaturized multi-layer ultra-wideband millimeter-wave frequency selective surface according to claim 6, characterized in that: The ratio of the ring width of the metal ring patch to the diameter of the metal ring patch is 1:8, and the ratio of the horizontal axis length of the cross-shaped patch to the diameter of the metal ring patch is 17:

40.

8. The miniaturized multi-layer ultra-wideband millimeter-wave frequency selective surface according to claim 1, characterized in that: The thickness of the first metal patch layer (1), the second metal patch layer (3) and the third metal patch layer (5) are all 0.3 to 0.5 μm.

9. The miniaturized multi-layer ultra-wideband millimeter-wave frequency selective surface according to claim 1, characterized in that: The thickness of the first dielectric layer (2) is 0.65 to 0.75 mm, the thickness of the second dielectric layer (4) is 0.5 to 0.6 mm, and the thickness of the third dielectric layer (6) is 0.45 to 0.55 mm.

10. The miniaturized multi-layer ultra-wideband millimeter-wave frequency selective surface according to claim 9, characterized in that: The first dielectric layer (2), the second dielectric layer (4) and the third dielectric layer (6) are all made of float soda-lime glass, and the relative dielectric constants of the first dielectric layer (2), the second dielectric layer (4) and the third dielectric layer (6) are 6 to 6.5.

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