Dual-band and angle-stable frequency selective surface unit and structure

Abstract

The invention relates to the technical field of antenna microwaves, in particular to a dual-band and angle-stable frequency selective surface unit and structure. The dual-band and angle-stable frequency selective surface unit comprises a first base layer, a metal periodic structure layer and a second base layer which are stacked in sequence, wherein the metal periodic structure layer comprises a first hexagonal metal ring, a second hexagonal metal ring and a third hexagonal metal ring which correspond to each other in angle, are sleeved in sequence and are arranged at intervals; the width of the second hexagonal metal ring is larger than the width of the first hexagonal metal ring and the width of the third hexagonal metal ring, notches are formed in the six corners of the second hexagonal metal ring, and polygonal metal blocks spaced from the second hexagonal metal ring and the third hexagonal metal ring are arranged at the notches. The problems of poor angle stability, large passband insertion loss, out-of-band grating lobes and rejection deterioration existing in the existing FSS design in the prior art can be solved.

Description

Technical Field

[0001] The invention relates to the field of antenna microwave technology, and in particular to a dual-band and angle-stable frequency selective surface unit and structure. Background Art

[0002] A frequency selective surface (FSS) refers to a two-dimensional periodic structure composed of metal patch units or aperture units periodically arranged on a dielectric surface. It can cause electromagnetic waves to be fully reflected (patch-type FSS) or fully transmitted (aperture-type FSS) at the resonant frequency. It is a spatial filter that selects the incident angle, polarization mode, and frequency of electromagnetic waves. It is widely used in various bands of the electromagnetic spectrum, such as radome bandpass filters, frequency separators and polarization separators for satellite communications, and frequency selective windows used in architectural glass.

[0003] With the continuous improvement of radome stealth performance and the rapid development of modern communication technology, miniaturization and multi-frequency FSS have become research hotspots.

[0004] However, existing FSS designs have problems such as poor angular stability, large passband insertion loss, and deteriorated suppression due to the appearance of grating lobes out of band. Summary of the invention

[0005] In view of the defects existing in the prior art, the purpose of the present invention is to provide a dual-band and angle-stable frequency selective surface unit and structure, which can solve the problems of poor angle stability, large passband insertion loss, out-of-band grating lobes, and deteriorated suppression in the existing FSS design in the prior art.

[0006] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0007] On the one hand, the present invention provides a dual-band and angle-stable frequency selective surface unit, comprising: a first base layer, a metal periodic structure layer and a second base layer stacked in sequence, the metal periodic structure layer comprising a first hexagonal metal ring, a second hexagonal metal ring and a third hexagonal metal ring which are angle-corresponding, sequentially nested and spaced apart; the width of the second hexagonal metal ring is greater than the widths of the first hexagonal metal ring and the third hexagonal metal ring, and notches are provided on the six corners of the second hexagonal metal ring, and polygonal metal blocks spaced apart from the second hexagonal metal ring and the third hexagonal metal ring are provided at the notches.

[0008] In some optional schemes, the polygonal metal block is a regular hexagon, a parallelogram, a regular quadrilateral, an equilateral triangle or a Y shape.

[0009] In some optional schemes, the gap is a parallelogram, and the polygonal metal block is a parallelogram.

[0010] In some optional schemes, the side length of the notch in the shape of a parallelogram is 0.4 mm, and the side length of the polygonal metal block in the shape of a parallelogram is 0.3 mm.

[0011] In some optional schemes, the first base layer includes a first fiberglass reinforced plastic and a first adhesive film which are arranged in sequence, and the first fiberglass reinforced plastic is located at the outermost side.

[0012] In some optional schemes, the second base layer includes a polyimide film, a second adhesive film and a second fiberglass reinforced plastic arranged in sequence, and the second fiberglass reinforced plastic is located at the outermost side.

[0013] In some optional schemes, the thickness of the first fiberglass reinforced plastic and the second fiberglass reinforced plastic is 0.2-0.6 mm, and the dielectric constant is 2.1-3.1.

[0014] In some optional schemes, the dielectric constant of the first adhesive film and the second adhesive film is 2.0-2.6, and the thickness is 0.01-0.035 mm.

[0015] In some optional schemes, the polyimide film has a thickness of 0.02-0.06 mm and a dielectric constant of 1.9-3.3.

[0016] On the other hand, the present invention further provides a dual-band and angle-stable frequency selective surface structure, which includes a plurality of the above-mentioned dual-band and angle-stable frequency selective surface units arranged in sequence.

[0017] Compared with the prior art, the advantages of the present invention are: a first base layer and a second base layer are respectively arranged on both sides of the metal periodic structure layer, which can improve the strength of the entire structure; the metal periodic structure layer is designed to correspond in angle, to be nested in sequence, and to be spaced apart, and to couple to achieve dual-band broadband; notches are arranged at the six corners of the second hexagonal metal ring, and polygonal metal blocks are arranged at the notches, and are spaced apart from the second hexagonal metal ring and the third hexagonal metal ring; the incompleteness of the second hexagonal metal ring is utilized to achieve resonance interruption and avoid grating lobes. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 It is a schematic structural diagram of a dual-band and angle-stable frequency selective surface unit in an embodiment of the present invention;

[0020] Figure 2 Schematic diagram of the structure of a metal periodic structure layer in an embodiment of the present invention;

[0021] Figure 3 is an S12 curve diagram of the frequency selective surface structure in an embodiment of the present invention;

[0022] Figure 4 is a graph of S11 of the frequency selective surface structure according to an embodiment of the present invention;

[0023] In the figure: 1. first base layer; 11. first glass fiber reinforced plastic; 12. first adhesive film; 2. metal periodic structure layer; 21. first hexagonal metal ring; 22. second hexagonal metal ring; 23. third hexagonal metal ring; 24. polygonal metal block; 3. second base layer; 31. polyimide film; 32. second adhesive film; 33. second glass fiber reinforced plastic. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0025] The embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0026] Figure 1 is a schematic diagram of the structure of a dual-band and angle-stable frequency selective surface unit in an embodiment of the present invention, Figure 2 Schematic diagram of the structure of the metal periodic structure layer in the embodiment of the present invention, Figure 1 and Figure 2 As shown, on the one hand, the present invention provides a dual-band and angle-stable frequency selective surface unit, comprising: a first base layer 1, a metal periodic structure layer 2 and a second base layer 3 are stacked in sequence, the metal periodic structure layer 2 comprises a first hexagonal metal ring 21, a second hexagonal metal ring 22 and a third hexagonal metal ring 23 which are arranged in sequence and at intervals at corresponding angles; the width of the second hexagonal metal ring 22 is greater than the widths of the first hexagonal metal ring 21 and the third hexagonal metal ring 23, and the six corners of the second hexagonal metal ring 22 are provided with notches, and a polygonal metal block 24 spaced from the second hexagonal metal ring 22 and the third hexagonal metal ring 23 is provided at the notch.

[0027] In this solution, a first base layer 1 and a second base layer 3 are respectively arranged on both sides of the metal periodic structure layer 2, which can improve the strength of the entire structure. The metal periodic structure layer 2 is designed to be angle-corresponding, sequentially nested, and spaced apart. The first hexagonal metal ring 21, the second hexagonal metal ring 22, and the third hexagonal metal ring 23 are coupled to achieve dual-band broadband. The first hexagonal metal ring 21 regulates the first frequency band, and the third hexagonal metal ring 23 regulates the second frequency band. Notches are set on the six corners of the second hexagonal metal ring 22, and polygonal metal blocks 24 are set at the notches and spaced apart from the second hexagonal metal ring 22 and the third hexagonal metal ring 23. The incompleteness of the second hexagonal metal ring 22 is used to achieve resonance interruption and avoid grating lobes.

[0028] In this example, the outer contours of the first base layer 1, the metal periodic structure layer 2 and the second base layer 3 are all regular hexagons, and the first hexagonal metal ring 21, the second hexagonal metal ring 22 and the third hexagonal metal ring 23 are also regular hexagons.

[0029] The first hexagonal metal ring 21 in the metal periodic structure layer 2 has an outer side length of 2.2-2.8 mm and a width of 0.1-0.25 mm, the outer side length of the third hexagonal metal ring 23 is 0.81-1.02 mm, and the gap between the polygonal metal block 24 and the second hexagonal metal ring 22 is 0.1-0.35 mm.

[0030] In some optional embodiments, the polygonal metal block 24 is a regular hexagon, a parallelogram, a regular quadrilateral, a regular triangle or a Y shape.

[0031] In this embodiment, the notches provided at the six corners of the second hexagonal metal ring 22 may also be a regular hexagon, a parallelogram, a regular quadrilateral, an equilateral triangle or a Y shape, and the polygonal metal block 24 may be a regular hexagon, a parallelogram, a regular quadrilateral, an equilateral triangle or a Y shape, and the incompleteness caused by providing notches at the six corners of the second hexagonal metal ring 22 may be utilized to achieve resonance interruption and avoid grating lobes. The specific shape may be selected based on the optimal shape and size selected according to the test.

[0032] In some optional embodiments, the notch is a parallelogram, and the polygonal metal block 24 is a parallelogram.

[0033] In this embodiment, according to experiments, the notch is a parallelogram and the polygonal metal block 24 is a parallelogram, which can bring better stability, achieve resonance interruption, and avoid the effect of grating lobes.

[0034] In some optional embodiments, the side length of the notch in the shape of a parallelogram is 0.4 mm, and the side length of the polygonal metal block 24 in the shape of a parallelogram is 0.3 mm.

[0035] In addition, in this solution, the outer side length of the first hexagonal metal ring 21 in the metal periodic structure layer 2 is 2.4 mm, the inner side length is 2.2 mm, the outer side length of the third hexagonal metal ring 23 is 0.92 mm, the outer side length of the regular hexagon of the second hexagonal metal ring 22 is 1.7 mm, the side length of the notch in the shape of a parallelogram is 0.4 mm, and the side length of the polygonal metal block 24 is 0.3 mm. Such a size design can bring better stability, achieve resonance interruption, and avoid the effect of grating lobes.

[0036] In some optional embodiments, the first base layer 1 includes a first fiberglass reinforced plastic 11 and a first adhesive film 12 which are arranged in sequence, and the first fiberglass reinforced plastic 11 is located at the outermost side.

[0037] In some optional embodiments, the second base layer 3 includes a polyimide film 31 , a second adhesive film 32 , and a second fiberglass reinforced plastic 33 which are arranged in sequence, and the second fiberglass reinforced plastic 33 is located at the outermost side.

[0038] In some optional embodiments, the thickness of the first glass fiber reinforced plastic 11 and the second glass fiber reinforced plastic 33 is 0.2-0.6 mm, and the dielectric constant is 2.1-3.1.

[0039] FRP has high strength and rigidity and can withstand large external forces. FRP is set on both sides of the frequency selective surface as a supporting structure to ensure the stability and reliability of the frequency selective surface in complex environments. FRP is a non-metallic material with a low dielectric constant and loss tangent, which helps to optimize the electromagnetic performance of the frequency selective surface. FRP can reduce the reflection loss and insertion loss of the frequency selective surface and improve the transmission efficiency and frequency selectivity of the frequency selective surface. In addition, FRP has a small attenuation effect on electromagnetic waves, which can ensure that the frequency selective surface maintains stable performance within the working frequency band.

[0040] The inner and outer layers of the overall structure adopt a glass fiber reinforced plastic seat heat protection layer structure, namely the first glass fiber reinforced plastic 11 and the second glass fiber reinforced plastic 33. The parameters are that the thickness of the first glass fiber reinforced plastic 11 and the second glass fiber reinforced plastic 33 is 0.2-0.6mm, the dielectric constant is 2.1-3.1, and it can withstand a temperature of 600°C, which greatly improves the strength and high temperature resistance of the structure.

[0041] In some optional embodiments, the dielectric constant of the first adhesive film 12 and the second adhesive film 32 is 2.0-2.6, and the thickness is 0.01-0.035 mm.

[0042] In this embodiment, the role of the adhesive film in the frequency selective surface is to fix the structure and bond the layers. The first fiberglass 11, the second fiberglass 33 and the polyimide film 31 need a stable fixing method to ensure the overall performance and stability of the entire frequency selective surface. As a bonding material, the adhesive film can effectively bond these different layers together to form an integral multilayer structure. The adhesive film can ensure close contact between the layers of the frequency selective surface and prevent performance degradation caused by looseness or separation between layers. This close bonding helps to improve the resonant frequency stability and bandwidth stability of the frequency selective surface.

[0043] The dielectric constant directly affects the overall performance and stability of the frequency selective surface. The thickness of the adhesive film is also an important factor affecting the performance of the frequency selective surface. An overly thick adhesive film may increase the overall thickness of the frequency selective surface, thereby affecting its electromagnetic performance. Therefore, the thickness of the adhesive film needs to be strictly controlled to meet the design requirements. In this solution, the dielectric constant of the first adhesive film 12 and the second adhesive film 32 is 2.0-2.6, and the thickness is 0.01-0.035mm, which can make the entire structure have good stability and electromagnetic performance.

[0044] In this example, the dielectric constant of the first adhesive film 12 and the second adhesive film 32 is 2.0-2.6, and the thickness is 0.01-0.035 mm, so that the entire structure has better stability and electromagnetic performance.

[0045] In some optional embodiments, the polyimide film 31 has a thickness of 0.02-0.06 mm and a dielectric constant of 1.9-3.3.

[0046] In the above embodiment, the polyimide film is used as a flexible medium to support the metal periodic structure layer 2. Its flexibility and mechanical properties enable the frequency selective surface structure to adapt to different shape and size requirements while maintaining stable performance. In addition, the polyimide film has outstanding high temperature resistance and can be used for a long time in air at 250-280°C. This feature enables the frequency selective surface to be used in high temperature environments. The polyimide film has excellent radiation resistance and chemical corrosion resistance, and can resist corrosion from a variety of chemical solvents and weak acids. The polyimide film also has excellent electrical insulation properties.

[0047] A specific embodiment is given below: the unit structure of the first glass fiber reinforced plastic 11 and the second glass fiber reinforced plastic 33 is a regular hexagon, the material of the metal periodic structure layer 2 is copper, the dielectric constant of the polyimide film 31 is 3.1, the dielectric constant of the first adhesive film 12 and the second adhesive film 32 is 2.45, the thickness of the first glass fiber reinforced plastic 11 and the second glass fiber reinforced plastic 33 is 0.2 mm, the thickness of the polyimide film 31 is 0.04 mm, the dielectric constant is 3.1, the thickness of the metal periodic structure layer 2 is 0.025 mm, the thickness of the first adhesive film 12 and the second adhesive film 32 is 0.02 mm, and the dielectric constant is 2.45.

[0048] The polygonal metal block 24 in the metal periodic structure layer 2 is a parallelogram, and the gaps set on the six corners of the second hexagonal metal ring 22 are also parallelograms. The outer side length of the first hexagonal metal ring 21 in the metal periodic structure layer 2 is 2.4 mm, and the inner side length is 2.2 mm. The outer side length of the third hexagonal metal ring 23 is 0.92 mm, the side length of the second hexagonal metal ring 22 is 1.7 mm, and the gap is a parallelogram with a side length of 0.4 mm. The side length of the polygonal metal block 24 is 0.3 mm, and the gap between the polygonal metal block 24 and the second hexagonal metal ring 22 is 0.2 mm.

[0049] In the prior art, as the incident angle increases by 50 degrees, the bandwidth less than -0.5dB becomes narrower, and the S12 value is less than -0.5dB. The frequency selective surface of the present technical solution is used and tested to obtain the S12 curve and the S11 curve. From the transmittance curve reflected by S11 and the reflectance curve reflected by S12 in the figure, it can be seen that the frequency selective surface corresponding to the present technical solution does not show a decrease in bandwidth until 65 degrees, but the transmittance remains unchanged.

[0050] On the other hand, the present invention further provides a dual-band and angle-stable frequency selective surface structure, which includes a plurality of the dual-band and angle-stable frequency selective surface units arranged in sequence.

[0051] In this example, the dual-band and angle-stable frequency selective surface structure adopts a plurality of the above-mentioned dual-band and angle-stable frequency selective surface units arranged in sequence, and each unit is respectively provided with a first base layer 1 and a second base layer 3 on both sides of the metal periodic structure layer 2, which can improve the strength of the entire structure, and the metal periodic structure layer 2 is designed to correspond in angle, be nested in sequence, and be spaced apart from each other. The first hexagonal metal ring 21, the second hexagonal metal ring 22 and the third hexagonal metal ring 23 are coupled to realize dual-band broadband, and notches are provided on the six corners of the second hexagonal metal ring 22, and a polygonal metal block 24 is provided at the notch, and is spaced apart from the second hexagonal metal ring 22 and the third hexagonal metal ring 23, and the imperfection of the second hexagonal metal ring 22 is utilized to realize resonance interruption and avoid grating lobes.

[0052] The inner and outer layers of the overall structure adopt a glass fiber reinforced plastic seat heat protection layer structure, namely the first glass fiber reinforced plastic 11 and the second glass fiber reinforced plastic 33. The parameters are that the thickness of the first glass fiber reinforced plastic 11 and the second glass fiber reinforced plastic 33 is 0.2-0.6mm, the dielectric constant is 2.1-3.1, and it can withstand a temperature of 600°C, which greatly improves the strength and high temperature resistance of the structure.

[0053] The adhesive film ensures close contact between the layers of the frequency selective surface, preventing performance degradation caused by loosening or separation between the layers. This close adhesion helps improve the resonant frequency stability and bandwidth stability of the frequency selective surface.

[0054] The dielectric constant directly affects the overall performance and stability of the frequency selective surface. The thickness of the adhesive film is also an important factor affecting the performance of the frequency selective surface. An overly thick adhesive film may increase the overall thickness of the frequency selective surface, thereby affecting its electromagnetic performance. Therefore, the thickness of the adhesive film needs to be strictly controlled to meet the design requirements. In this solution, the dielectric constant of the first adhesive film 12 and the second adhesive film 32 is 2.0-2.6, and the thickness is 0.01-0.035mm, which can make the entire structure have good stability and electromagnetic performance.

[0055] The polyimide film is used as a flexible medium to support the metal periodic structure layer 2. Its flexibility and mechanical properties enable the frequency selective surface structure to adapt to different shape and size requirements while maintaining stable performance.

[0056] In the description of the present application, it should be noted that the terms "upper", "lower", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0057] It should be noted that, in this application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0058] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A dual-band and angle-stable frequency selective surface unit, characterized in that: include: A first base layer (1), a metal periodic structure layer (2) and a second base layer (3) are stacked in sequence, the metal periodic structure layer (2) comprising a first hexagonal metal ring (21), a second hexagonal metal ring (22) and a third hexagonal metal ring (23) which are arranged at corresponding angles, in sequence and at intervals; the width of the second hexagonal metal ring (22) is greater than the widths of the first hexagonal metal ring (21) and the third hexagonal metal ring (23), and six corners of the second hexagonal metal ring (22) are each provided with a notch, and a polygonal metal block (24) is provided at the notch and is spaced from the second hexagonal metal ring (22) and the third hexagonal metal ring (23).

2. The dual-band and angle-stable frequency selective surface unit according to claim 1, characterized in that: The polygonal metal block (24) is a regular hexagon, a parallelogram, a regular quadrilateral, a regular triangle or a Y shape.

3. The dual-band and angle-stable frequency selective surface unit according to claim 1, characterized in that: The notch is a parallelogram, and the polygonal metal block (24) is a parallelogram.

4. The dual-band and angle-stable frequency selective surface unit according to claim 3, characterized in that: The side length of the notch in the shape of a parallelogram is 0.4 mm, and the side length of the polygonal metal block (24) in the shape of a parallelogram is 0.3 mm.

5. The dual-band and angle-stable frequency selective surface unit according to claim 1, characterized in that: The first base layer (1) comprises a first glass fiber reinforced plastic (11) and a first adhesive film (12) which are arranged in sequence, and the first glass fiber reinforced plastic (11) is located at the outermost side.

6. The dual-band and angle-stable frequency selective surface unit according to claim 5, characterized in that: The second base layer (3) comprises a polyimide film (31), a second adhesive film (32) and a second glass fiber reinforced plastic (33) which are arranged in sequence, and the second glass fiber reinforced plastic (33) is located at the outermost side.

7. The dual-band and angle-stable frequency selective surface unit according to claim 6, characterized in that: The thickness of the first glass fiber reinforced plastic (11) and the second glass fiber reinforced plastic (33) is 0.2-0.6 mm, and the dielectric constant is 2.1-3.

1.

8. The dual-band and angle-stable frequency selective surface unit according to claim 6, characterized in that: The dielectric constant of the first adhesive film (12) and the second adhesive film (32) is 2.0-2.6, and the thickness is 0.01-0.035 mm.

9. The dual-band and angle-stable frequency selective surface unit according to claim 6, characterized in that: The polyimide film (31) has a thickness of 0.02-0.06 mm and a dielectric constant of 1.9-3.

3.

10. A dual-band and angle-stable frequency selective surface structure, characterized in that: The invention comprises a plurality of dual-band and angle-stable frequency selective surface units as described in any one of claims 1 to 9 which are arranged in sequence.

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