Frequency Selective Surface and Electronic Device

Abstract

The present disclosure provides a frequency selective surface and an electronic device, belonging to the field of microwave technology, which can solve the problems of poor frequency selectivity and relatively thick thickness of the existing frequency selective surface. The frequency selective surface of the present disclosure includes: a dielectric substrate, and a plurality of resonant structures arranged in an array on the dielectric substrate; each resonant structure includes: a plurality of protruding portions arranged in a disconnected manner; the extending directions of the plurality of protruding portions intersect.

Description

Technical Field

[0001] The present invention belongs to the field of microwave technology, and in particular relates to a frequency selective surface and an electronic device. Background Art

[0002] The frequency selective surface (FSS) is a two-dimensional periodic array structure. In essence, it is a spatial filter, and its interaction with electromagnetic waves shows obvious passband or band-stop filtering characteristics. Under the trend of 5G industrial interconnection, in order to achieve high-speed data transmission in factories, industry experts have expressed that the 4.9GHz band (ie, the N79 band: 4800MHz-4900MHz) is expected to become a favorable frequency band for large-scale uplink of industrial Internet data. However, in today's complex electromagnetic wave environment, electromagnetic waves in different frequency bands often affect the quality of communication between communication devices due to crosstalk. Therefore, the development of a band-stop frequency selective surface that can effectively block the penetration and leakage of electromagnetic waves in this frequency band inside and outside the factory will become a hot topic.

[0003] The current frequency selective surfaces are all broadband frequency selective surfaces, that is, low frequency selective surface structures. Although such structures can successfully block the transmission of electromagnetic waves in the target frequency band, such structures will still block electromagnetic waves in other frequency bands outside the target frequency band. Therefore, the frequency selectivity of such structures is not perfect. In order to improve the frequency selectivity, a single-layer structure and a multi-layer cascade are generally used. However, the multi-layer cascade method will increase the thickness of the structure and invisibly increase the weight of the structure as a whole. In addition, the current frequency selective surface structures are all non-transparent structures, which are not conducive to conformity with other structures and affect the aesthetics of the structure. Summary of the invention

[0004] The present disclosure aims to solve at least one of the technical problems existing in the prior art and provide a frequency selective surface and an electronic device.

[0005] In a first aspect, an embodiment of the present disclosure provides a frequency selective surface, the frequency selective surface comprising: a dielectric substrate, and a plurality of resonant structures arranged in an array on the dielectric substrate;

[0006] Each of the resonant structures comprises: a plurality of protrusions which are arranged in a disconnected manner; and the extension directions of the plurality of protrusions intersect with each other.

[0007] Optionally, the protrusion includes: a U-shaped portion, a first connecting portion and a second connecting portion;

[0008] One end of the U-shaped portion is connected to the first connection portion, and the other end is connected to the second connection portion.

[0009] Optionally, the U-shaped part includes: a third connecting part, a fourth connecting part, and a fifth connecting part;

[0010] One end of the third connecting part and one end of the fourth connecting part are respectively connected to both ends of the fifth connecting part, and the third connecting part and the fourth connecting part are arranged oppositely,

[0011] The other end of the third connecting part is connected to the first connecting part, and the other end of the fourth connecting part is connected to the second connecting part.

[0012] Optionally, in the same resonance structure, the sides of adjacent fifth connecting parts are at least partially arranged oppositely.

[0013] Optionally, in the same resonance structure, a plurality of the fifth connecting parts enclose a hollow opening.

[0014] Optionally, the first connecting part, the second connecting part, the third connecting part, the fourth connecting part, and the fifth connecting part are of an integrally formed structure.

[0015] Optionally, each resonance structure includes: four of the protruding parts; wherein,

[0016] Two opposite protruding parts are arranged axially symmetrically.

[0017] Optionally, the dielectric substrate includes: a transparent dielectric substrate.

[0018] Optionally, the protruding part includes: a metal patch.

[0019] Optionally, the metal patch includes: a plurality of metal grid lines.

[0020] In a second aspect, an embodiment of the present disclosure provides an electronic device, including the frequency selective surface provided above. Description of the Drawings

[0021] Figure 1 It is a schematic structural diagram of an exemplary frequency selective surface;

[0022] Figure 2 It is a schematic structural diagram of a frequency selective surface provided by an embodiment of the present disclosure;

[0023] Figure 3 For Figure 2 It is a schematic structural diagram of a resonance structure in the frequency selective surface shown;

[0024] Figure 4 It is a schematic structural diagram of a resonance structure in an exemplary frequency selective surface;

[0025] Figure 5 For Figure 4Schematic diagram of the insertion loss of the frequency selective surface shown;

[0026] Figure 6 Schematic diagram of the structure of the resonant structure in another exemplary frequency selective surface;

[0027] Figure 7 is Figure 6 Schematic diagram of the insertion loss of the frequency selective surface shown;

[0028] Figure 8 is Figure 2 Schematic diagram of the insertion loss of a frequency selective surface shown. Detailed implementation manners

[0029] To enable those skilled in the art to better understand the technical solutions of the present disclosure, the present disclosure will be further described in detail below with reference to the accompanying drawings and specific implementation manners.

[0030] Unless otherwise defined, the technical terms or scientific terms used in the present disclosure shall have the ordinary meanings understood by those of ordinary skill in the art to which the present disclosure pertains. The "first", "second" and similar terms used in the present disclosure do not denote any order, quantity or importance, but are only used to distinguish different components. Similarly, the terms such as "a", "an" or "the" do not denote a quantity limitation, but mean that there is at least one. The terms such as "comprising" or "including" mean that the elements or objects appearing before this word cover the elements or objects listed after this word and their equivalents, without excluding other elements or objects. The terms such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The terms such as "upper", "lower", "left" and "right" are only used to represent relative positional relationships, and when the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0031] Figure 1 Schematic diagram of the structure of an exemplary frequency selective surface, such as Figure 1As shown, the frequency selective surface includes: a dielectric substrate 101, and a plurality of resonant structures 102 arranged in an array on the dielectric substrate 101. The dielectric substrate 101 is generally made of a printed circuit board, which is a hard non-transparent material, and can effectively support the resonant structure 102 formed thereon. The resonant structure 102 can be made of a metal patch, and a hollow opening can be formed in the metal patch to block the electromagnetic waves of the corresponding target frequency band and transmit the electromagnetic waves of other frequency bands, thereby avoiding the interference of signals carried by electromagnetic waves of different frequency bands, and thus improving the communication quality. However, the current frequency selective surfaces are all wide-band stop frequency selective surfaces, that is, low-frequency selective surface structures. Although such structures can successfully block the transmission of electromagnetic waves in the target frequency band, such structures will still have a blocking effect on electromagnetic waves in other frequency bands outside the target frequency band. Therefore, the frequency selectivity of such structures is not perfect. In order to improve the frequency selectivity, a single-layer structure and a multi-layer cascade are generally used. However, the multi-layer cascade method will increase the thickness of the structure and invisibly increase the weight of the structure as a whole. Moreover, the current frequency selective surface structures are all non-transparent structures, which are not conducive to conformity with other structures and affect the aesthetics of the structure.

[0032] In order to solve at least one of the above-mentioned technical problems existing in the frequency selective surface in the related art, the embodiment of the present disclosure provides a frequency selective surface and an electronic device. The frequency selective surface and the electronic device provided by the embodiment of the present disclosure will be further described in detail below in combination with the accompanying drawings and specific implementation methods.

[0033] In a first aspect, an embodiment of the present disclosure provides a frequency selective surface, Figure 2 A schematic diagram of the structure of a frequency selective surface provided by an embodiment of the present disclosure is shown in FIG. Figure 2 As shown, the frequency selective surface includes: a dielectric substrate 101, and a plurality of resonant structures 102 arranged in an array on the dielectric substrate 101; each resonant structure 102 includes: a plurality of protrusions 103 that are arranged in a disconnected manner; and the extension directions of the plurality of protrusions 103 intersect.

[0034] The dielectric substrate 101 can be made of a square plate, which can effectively support the resonant structure 102 printed thereon, and ensure the polarization stability of the resonant structure 102. The specific size of the dielectric substrate 101 can be set according to the size of the resonant structure 102, and is not limited here. It can be understood that the shape of the dielectric substrate 101 can also be other shapes such as triangles and polygons, which are not listed here. Its dielectric constant can be 2.0 to 3.0, and it can be made of a material with a suitable relative dielectric constant according to actual needs.

[0035] The resonant structure 102 may be composed of a plurality of protrusions 103 that are disconnected and arranged, and the extension directions of the plurality of protrusions 103 intersect, wherein the protrusions 103 may be made of a metal material or a non-metal material with good electrical conductivity, which may block electromagnetic waves in the target frequency band and transmit electromagnetic waves other than the target frequency band to ensure good communication quality. The frequency band of electromagnetic waves blocked by the resonant structure 102 as a whole may be adjusted by adjusting the spacing between the internal structures of the protrusions 103 and the spacing between adjacent protrusions 103.

[0036] In the embodiment of the present disclosure, the electromagnetic waves in the 4.9GHz frequency band (i.e., the N79 frequency band: 4800MHz-4900MHz) are taken as the target frequency band. After testing, the frequency selective surface provided in the embodiment of the present disclosure can have good frequency selectivity for the electromagnetic waves in the above target frequency band, and can effectively block the electromagnetic waves in the target frequency band. In this way, only one layer of resonant structure 102 can be used to achieve the steepness of the insertion loss curve on both sides of the target frequency band, so that the insertion loss characteristics of the commonly used low-frequency band (700MHz-3500MHz) can be as low as less than 1dB. Therefore, it is not necessary to adopt a multi-layer cascade method to improve its frequency selectivity. Therefore, while ensuring that the frequency selective surface has good frequency selectivity, the thickness of the frequency selective surface can be reduced, which is conducive to the thinness of the product and improves the user experience.

[0037] Figure 3 for Figure 2 A schematic diagram of the structure of a resonant structure in a frequency selective surface is shown in FIG. Figure 3 As shown, each protrusion 103 in the resonant structure 102 includes: a U-shaped portion, a first connecting portion 1031 and a second connecting portion 1032 ; one end of the U-shaped portion is connected to the first connecting portion 1031 , and the other end is connected to the second connecting portion 1032 .

[0038] In the embodiment of the present disclosure, the same resonant structure 102 may be provided with multiple protrusions 103, that is, multiple U-shaped portions, the bottoms of the U-shaped portions are close to each other, the openings of the U-shaped portions are far away from each other, and are arranged in a surrounding manner. The extension direction of the protrusion 103 is away from the opening of the U-shaped portion. The two ends of the U-shaped portion are respectively connected to the first connecting portion 1031 and the second connecting portion 1032, so as to form a Figure 3 In order to facilitate understanding of the frequency selection characteristics of the frequency selective surface provided by the embodiment of the present disclosure, the frequency selective surface provided by the embodiment of the present disclosure will be described below by comparing with two other frequency selective surfaces in the related art. Figure 4 FIG. 1 is a schematic diagram of a structure of a resonant structure in an exemplary frequency selective surface. Figure 4 As shown, the resonant structure in the frequency selective surface is ring-shaped. Figure 5 forFigure 4 Insertion loss schematic diagram of the frequency selective surface shown, such as Figure 5 shown, the frequency selective surface of the ring resonator structure has good wideband selection characteristics. The frequency selective surface of the ring resonator structure satisfies the insertion loss characteristics of 4.14 GHz - 5.75 GHz (bandwidth: 1.61 GHz) under the -10 dB standard, while the insertion loss in the 3.5 GHz frequency band is only -5.08 dB. Therefore, although the frequency selective surface of this ring resonator structure can easily block the target frequency band (4800 MHz - 4960 MHz), it cannot achieve low loss in the commonly used low frequency band (700 MHz - 3500 MHz). Figure 6 Schematic diagram of the resonator structure in another exemplary frequency selective surface, such as Figure 6 shown, the resonator structure in this frequency selective surface is in a "rice" shape. Figure 7 For Figure 6 Insertion loss schematic diagram of the frequency selective surface shown, such as Figure 7 shown, the "rice" shaped frequency selective surface can satisfy the -10 dB insertion loss bandwidth of 4.49 GHz - 5.32 GHz (bandwidth: 830 MHz). Although the frequency selectivity is improved compared to the ring frequency selective surface, it still cannot effectively reduce the insertion loss characteristics at the 3.5 GHz frequency point. As Figure 7 shown, this "rice" shaped frequency selective surface can only achieve an insertion loss characteristic of -2.3 dB at the 3.5 GHz frequency point, and this "rice" shaped frequency selective surface also cannot reduce the insertion loss at the 3.5 GHz frequency point to less than 1 dB. Figure 8 For Figure 2 Insertion loss schematic diagram of a frequency selective surface shown, such as Figure 8 shown, the frequency selective surface provided by the embodiments of the present disclosure can satisfy the -10 dB insertion loss characteristics of 4.79 GHz - 4.96 GHz (bandwidth: 170 MHz), and can effectively reduce the insertion loss in the 3.5 GHz frequency band to less than 1 dB. Currently, the frequency selective surface provided by the embodiments of the present disclosure can achieve an insertion loss characteristic of -0.74 dB in the 3.5 GHz frequency band. It can be seen that the frequency selective surface provided by the embodiments of the present disclosure has very excellent frequency selection characteristics, ensuring efficient transmission in the commonly used low frequency band (700 MHz - 3500 MHz). In this way, it is not necessary to use a multi-level cascade method to improve its frequency selectivity, so that while ensuring good frequency selectivity of the frequency selective surface, the thickness of the frequency selective surface can be reduced, which is beneficial to the thinning of the product and improves the user experience.

[0039] In some embodiments, the U-shaped portion includes: a third connecting portion 1033, a fourth connecting portion 1034, and a fifth connecting portion 1035; one end of the third connecting portion 1033 and one end of the fourth connecting portion 1034 are respectively connected to two ends of the fifth connecting portion 1035, and the third connecting portion 1033 and the fourth connecting portion 1034 are oppositely arranged, the other end of the third connecting portion 1033 is connected to the first connecting portion 1031, and the other end of the fourth connecting portion 1034 is connected to the second connecting portion 1032.

[0040] The third connecting portion 1033 and the fourth connecting portion 1034 in the U-shaped portion are oppositely arranged. Specifically, the third connecting portion 1033 and the fourth connecting portion 1034 may be parallel to each other and are connected by the fifth connecting portion 1035. It should be noted that in order to ensure excellent frequency selection characteristics of the overall frequency selective surface, the ends of the first connecting portion 1031, the second connecting portion 1032, the third connecting portion 1033, the fourth connecting portion 1034, and the fifth connecting portion 1035 may adopt a chamfered form, that is, each end may be a non-right-angled shape. In practical applications, the frequency band of the electromagnetic wave blocked by the entire frequency selective surface can be adjusted by adjusting the distance between the third connecting portion 1033 and the fourth connecting portion 1034, so as to block the electromagnetic wave in the target frequency band (4800 MHz - 4960 MHz) and enable efficient transmission in the common low frequency band (700 MHz - 3500 MHz). In this way, it is not necessary to adopt a multi-layer cascading method to improve its frequency selectivity. Thus, while ensuring good frequency selectivity of the frequency selective surface, the thickness of the frequency selective surface can be reduced, which is conducive to the thinning and lightening of the product, thereby improving the user experience. It can be understood that in the embodiments of the present disclosure, each protrusion 103 may be composed of five connecting portions to form an "Ω" shape, and the number of connecting portions may also be other numbers to form more "Ω" shapes to improve the overall frequency selection characteristics of the frequency selective surface. The specific number can be set according to actual needs and will not be elaborated here.

[0041] In some embodiments, in the same resonant structure 102, the sides of adjacent fifth connecting portions 1035 are at least partially oppositely arranged.

[0042] The sides of adjacent fifth connecting portions 1035 may be at least partially oppositely arranged, and a certain gap may be formed between them. The overall capacitance value of the resonant structure 102 can be adjusted by adjusting the size of the gap, so that the resonant bandwidth is greatly reduced to meet the -10 dB insertion loss characteristic in the range of 4.79 GHz - 4.96 GHz (bandwidth: 170 MHz), and the insertion loss in the 3.5 GHz frequency band can be effectively reduced to be lower than 1 dB, ensuring good frequency selectivity of the frequency selective surface.

[0043] In some embodiments, in the same resonant structure, the respective fifth connection portions 1035 enclose a hollow opening.

[0044] The hollow opening formed by enclosing the respective fifth connection portions 1035 has the same function as the gap between the adjacent fifth connection portions 1035 described above. It can adjust the overall capacitance value of the resonant structure 102, greatly reducing the resonant bandwidth to meet the -10dB insertion loss characteristic of 4.79 GHz - 4.96 GHz (bandwidth: 170 MHz), and can effectively reduce the insertion loss in the 3.5 GHz frequency band to below 1 dB, ensuring that the frequency selective surface has good frequency selectivity.

[0045] In some embodiments, the first connection portion 1031, the second connection portion 1032, the third connection portion 1033, the fourth connection portion 1034, and the fifth connection portion 1035 are an integrally formed structure.

[0046] In practical applications, the first connection portion 1031, the second connection portion 1032, the third connection portion 1033, the fourth connection portion 1034, and the fifth connection portion 1035 can be formed in one step by an imprinting process or an etching process, which can reduce the preparation steps and save the preparation cost. It can be understood that each connection portion can also be formed separately, and details are not described herein again.

[0047] In some embodiments, each resonant structure 102 includes: four protruding portions 103; two opposite protruding portions 103 are arranged axially symmetrically.

[0048] Specifically, each resonant structure 102 can include four disconnected protruding portions 103, and two opposite protruding portions 103 are arranged axially symmetrically, which can have good frequency selectivity for electromagnetic waves in the above target frequency band (4800 MHz - 4960 MHz), can effectively block the electromagnetic waves in the target frequency band (4800 MHz - 4960 MHz), and can make the insertion loss curves on both sides of the target frequency band steep with only one layer of resonant structure 102, enabling the insertion loss characteristic in the common low frequency band (700 MHz - 3500 MHz) to be as low as below 1 dB, and there is no need to adopt a multi - level cascade method to improve its frequency selectivity. Thus, while ensuring that the frequency selective surface has good frequency selectivity, the thickness of the frequency selective surface can be reduced, which is beneficial to the thinning of the product and improves the user experience. It can be understood that other numbers of protruding portions 103 can also be set to meet the needs of target frequencies in other frequency bands, and the principle is similar to that of the above frequency selective surface, and details are not described herein again.

[0049] In some embodiments, the dielectric substrate 101 includes: a transparent dielectric substrate.

[0050] The dielectric substrate 101 can be a transparent dielectric substrate, which can be a flexible dielectric substrate or a rigid dielectric substrate. The specific material can be a transparent plastic film or glass, so as to ensure that the frequency selective surface is overall transparent, enabling it to have excellent beautification characteristics or concealment. And it can be attached to the surfaces of objects such as transparent glass and transparent plastic to achieve the concealment characteristic and play the role of beautifying the environment.

[0051] In some embodiments, the protrusion 103 includes: a metal patch.

[0052] The protrusion 103 can be made of a metal patch. The width of the metal patch can be 1.5 millimeters to 3 millimeters. There is a certain gap between adjacent metal patches, so that light can pass through the gap, making the frequency selective surface have good light transmittance overall, so as to ensure that the frequency selective surface is overall transparent, enabling it to have excellent beautification characteristics or concealment. And it can be attached to the surfaces of objects such as transparent glass and transparent plastic to achieve the concealment characteristic and play the role of beautifying the environment. It can be understood that the protrusion 103 can also be made of other transparent conductive materials, and the principle is the same, which will not be listed one by one here.

[0053] In some embodiments, the metal patch includes a plurality of metal grid lines.

[0054] The metal patch can be made of metal grid lines. The size of the metal grid lines can reach the micron level. For example, the line width of the metal grid lines can be 2 microns to 30 microns, the thickness can be 1 micron to 10 microns, and the spacing between adjacent metal grid lines can be 50 microns to 200 microns. Since the size of the metal grid lines is small, the metal patch appears transparent as a whole, allowing light to pass through, so that the frequency selective surface as a whole has good light transmittance, ensuring that the frequency selective surface is transparent as a whole, enabling it to have excellent beautification characteristics or concealment. And it can be attached to the surface of objects such as transparent glass and transparent plastic to achieve the hiding feature and play the role of beautifying the environment. Corresponding to each structure in the protrusion 103, the first connecting portion 1031, the second connecting portion 1032, the third connecting portion 1033, the fourth connecting portion 1034, and the fifth connecting portion 1035 are all made of metal grid lines. The third connecting portion 1033 and the fifth connecting portion 1035 can be oppositely arranged, and can be arranged parallel to each other, and a hollow gap can be formed therebetween. Specifically, the spacing between the third connecting portion 1033 and the fifth connecting portion 1035 can be 50 microns to 200 microns. In this way, it can have good frequency selectivity for the electromagnetic waves in the above target frequency band (4800 MHz - 4960 MHz), can effectively block the electromagnetic waves in the target frequency band (4800 MHz - 4960 MHz), and can make the steepness of the insertion loss curves on both sides of the target frequency band be achieved with only one layer of the resonant structure 102. The insertion loss characteristic of the common low frequency band (700 MHz - 3500 MHz) can be as low as below 1 dB, and it is not necessary to adopt a multi-layer cascaded method to improve its frequency selectivity. Thus, while ensuring that the frequency selective surface has good frequency selectivity, the thickness of the frequency selective surface can be reduced, which is beneficial to the thinning of the product and improves the user experience.

[0055] In a second aspect, an embodiment of the present disclosure provides an electronic device, which includes the frequency selective surface provided in any of the above embodiments. The electronic device can be any product or component with a communication function such as a mobile phone, a tablet computer, a television, a laptop computer, a navigator, etc. The implementation principle of the electronic device and the technical effects it has can refer to the discussion of the implementation principle and technical effects of the frequency selective surface above, and will not be elaborated here.

[0056] It can be understood that the above embodiments are merely exemplary embodiments adopted to illustrate the principle of the present disclosure, but the present disclosure is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present disclosure, and these modifications and improvements are also regarded as the protection scope of the present disclosure.

Claims

1. A frequency selective surface, characterized in that, the frequency selective surface comprises: a dielectric substrate, and a plurality of resonant structures arranged in an array on the dielectric substrate; each of the resonant structures comprises: a plurality of protruding portions arranged discontinuously; the extending directions of the plurality of protruding portions intersect; the protruding portion comprises: a U-shaped portion, a first connecting portion and a second connecting portion; one end of the U-shaped portion is connected to the first connecting portion, and the other end is connected to the second connecting portion; the bottoms of the U-shaped portions are close to each other, and the openings of the U-shaped portions are far from each other and are arranged in a surrounding manner; the extending direction of the protruding portion is the direction away from the opening of the U-shaped portion therein.

2. The frequency selective surface according to claim 1, characterized in that, the U-shaped portion comprises: a third connecting portion, a fourth connecting portion and a fifth connecting portion; one end of the third connecting portion and one end of the fourth connecting portion are respectively connected to both ends of the fifth connecting portion, and the third connecting portion and the fourth connecting portion are arranged oppositely, the other end of the third connecting portion is connected to the first connecting portion, and the other end of the fourth connecting portion is connected to the second connecting portion.

3. The frequency selective surface according to claim 2, characterized in that, in the same resonant structure, the sides of adjacent fifth connecting portions are at least partially arranged oppositely.

4. The frequency selective surface according to claim 2, characterized in that, in the same resonant structure, a plurality of the fifth connecting portions enclose a hollow opening.

5. The frequency selective surface according to claim 2, characterized in that, the first connecting portion, the second connecting portion, the third connecting portion, the fourth connecting portion and the fifth connecting portion are of an integrally formed structure.

6. The frequency selective surface according to claim 1, characterized in that, each of the resonant structures comprises: four of the protruding portions; wherein, two opposite protruding portions are arranged axially symmetrically.

7. The frequency selective surface according to claim 1, characterized in that, the dielectric substrate comprises: a transparent dielectric substrate.

8. The frequency selective surface according to claim 1, characterized in that, the protruding portion comprises: a metal patch.

9. The frequency selective surface according to claim 8, characterized in that, the metal patch comprises: a plurality of metal grid lines.

10. An electronic device, characterized in that, comprises the frequency selective surface according to any one of claims 1-9.

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