Circularly polarized antenna array and method of manufacturing the same

Abstract

This invention discloses a circularly polarized antenna array and its fabrication method. A metasurface covering structure is mounted above the circularly polarized antenna array, with a 6.5mm high air layer between them. The metasurface covering structure includes an insulating dielectric layer and upper and lower metal arrays fixed to opposite sides of the insulating dielectric layer. Multiple lower metal elements of the upper metal array correspond one-to-one with multiple upper metal elements of the lower metal array on the insulating dielectric layer. Each upper metal element has two transverse slots, two longitudinal slots, and a central slot; each lower metal element is shaped like an inclined cross. The circularly polarized antenna array designed in this invention can introduce an indirect coupling field between adjacent antennas, canceling out the original coupling field and achieving decoupling. It is suitable for microstrip circularly polarized antenna arrays with very close element spacing. The decoupled circularly polarized antenna array can reduce the coupling between antennas and improve the radiation performance of the elements.

Description

Technical Field

[0001] This invention relates to the field of antenna decoupling, and more particularly to a circularly polarized antenna array and its fabrication method. Background Technology

[0002] Currently, wireless communication technology is evolving towards 6G. The demands for large channel capacity and high-speed transmission are driving the development of Multiple-Input Multiple-Output (MIMO) technology. In MIMO platforms, due to the miniaturization of the carrier and the large-scale integration of antennas, electromagnetic coupling between antennas cannot be ignored, thus reducing antenna performance. Reducing inter-antenna coupling is crucial for the development of wireless communication.

[0003] Circularly polarized antennas can receive electromagnetic waves with arbitrary linear polarization directions. Furthermore, when a circularly polarized wave is incident on a symmetrical target (such as a spherical water droplet in the air), the reflected electromagnetic wave rotates in the opposite direction. Circular polarization is widely used in vehicle-mounted and satellite communications because it can suppress rain and fog interference and reduce multipath interference.

[0004] Current decoupling techniques are mostly used for linearly polarized antenna arrays, and the decoupling methods used are not suitable for circularly polarized antenna arrays. Decoupling circularly polarized antenna arrays is more challenging than decoupling linearly polarized antenna arrays. Impedance matching, coupling level, and circular polarization axial ratio characteristics must be considered simultaneously in the operating frequency band. Summary of the Invention

[0005] To improve the isolation between existing antennas and enhance the radiation performance of individual elements, this invention provides a circularly polarized antenna array and its fabrication method. The circularly polarized antenna array utilizes a metasurface coating to modulate the electromagnetic field, achieving field phase cancellation to improve the isolation between antennas and enhance the radiation performance of individual elements.

[0006] This invention is achieved through the following technical solution: a circularly polarized antenna array, wherein a metasurface covering structure is installed above the circularly polarized antenna array, and an air layer is designed between the metasurface covering structure and the circularly polarized antenna array, the height of the air layer being 6.5mm; the metasurface covering structure includes an insulating dielectric layer and an upper metal array and a lower metal array respectively fixed on opposite sides of the insulating dielectric layer, wherein the lower metal array faces the circularly polarized antenna array;

[0007] The upper metal array comprises multiple upper metals arranged in a layered array. Each upper metal has two transverse slits that penetrate both ends of the corresponding upper metal in the transverse direction, two longitudinal slits that penetrate both ends of the corresponding upper metal in the longitudinal direction, and an intermediate slit between the two longitudinal slits and parallel to the two longitudinal slits. Both ends of the intermediate slit pass through the two transverse slits, but the length of the intermediate slit is less than the length of the two longitudinal slits.

[0008] The lower metal array comprises multiple lower metals arranged in a layered array, with each lower metal corresponding to one of the upper metals in a one-to-one correspondence on the insulating dielectric layer; each lower metal is in the shape of an inclined cross.

[0009] As a further improvement to the above scheme, the metasurface covering structure is fixed above the circularly polarized antenna array by multiple nylon struts.

[0010] As a further improvement to the above scheme, the spacing between two adjacent upper metal layers is 10 mm.

[0011] As a further improvement to the above scheme, each upper metal layer is square, with the two horizontal slits having the same width and the two vertical slits having the same width.

[0012] The widths of the two transverse gaps, the center distance between the two transverse gaps and the corresponding upper metal layer, the widths of the two longitudinal gaps, the center distance between the two longitudinal gaps and the corresponding upper metal layer, the length of the middle gap, the width of the middle gap, and the side length ratio of the corresponding upper metal layer are 0.4mm∶1.6mm∶0.2mm∶2.3mm∶6.4mm∶0.4mm∶8.4mm.

[0013] Furthermore, the major axis of each lower metal layer is formed by etching away two diagonally opposite equilateral right triangles with side length B mm from a positively oriented patch with side length A mm; the minor axis of each lower metal layer is formed by etching away two diagonally opposite equilateral right triangles with side length D mm from a positively oriented patch with side length C mm; A∶B∶C∶D is 5.6∶4.4∶3.6∶2.8.

[0014] As a further improvement to the above scheme, the circularly polarized antenna array includes:

[0015] The second insulating dielectric layer is located below the first insulating dielectric layer;

[0016] Two metal patches are fixed on the side of the insulating dielectric layer facing the insulating dielectric layer one;

[0017] The metallic ground layer is laid flat and fixed on the opposite side of the insulating dielectric layer two, facing away from the insulating dielectric layer one.

[0018] Furthermore, the dielectric constant of insulating dielectric layer one and insulating dielectric layer two are both 4.4, both are made of FR4, and both have a thickness of 1.5mm. The length and width of the two insulating dielectric layers are the same as the length and width of the circularly polarized antenna array.

[0019] Furthermore, the two metal patches are symmetrical about the insulating dielectric layer and are respectively provided with coaxial power supply structures; each metal patch is an equilateral right triangle with a side length of E mm etched diagonally in the positive direction, and the distance between the sides of the metal patch is G mm; E∶F∶G is 14∶4∶3.

[0020] The present invention also provides a method for fabricating the above-mentioned arbitrary circularly polarized antenna array, which includes the following steps:

[0021] First, a circularly polarized antenna array is designed. A coaxial feeding structure is designed in the antenna array layer of the circularly polarized antenna array. Four M3 through holes are symmetrically drilled at the four corners of the antenna array layer. The distance between the through holes is 55mm in length and 35mm in width.

[0022] Multiple upper metal layers and multiple lower metal layers are respectively engraved on opposite sides of insulating dielectric layer one; through holes are symmetrically drilled around insulating dielectric layer one, and their positions are consistent with the through holes on insulating dielectric layer two.

[0023] Install an insulating support structure at each pair of through-hole locations, leaving an air layer with a thickness of 6.5mm.

[0024] As a further improvement to the above scheme, when designing a circularly polarized antenna array, a metal patch layer and a metal ground layer are respectively etched on opposite sides of the second insulating dielectric layer to form the antenna array layer.

[0025] This invention utilizes a metasurface covering structure to improve the isolation between circularly polarized antenna arrays. The metasurface covering structure mainly consists of upper and lower metal layers and a dielectric layer. An air layer is designed between the metasurface covering structure and the antenna layers of the circularly polarized antenna array, and nylon struts can be used to fix the structure. The metasurface covering structure designed in this invention can be applied to microstrip circularly polarized antenna arrays with very close element spacing. The decoupled circularly polarized antenna array can reduce the coupling between antennas and improve the radiation performance of the elements.

[0026] Therefore, the metasurface designed in this invention can decouple microstrip circularly polarized antenna arrays with small margins, and has the following advantages:

[0027] 1. The introduction of a new resonant point broadens the impedance matching bandwidth, and the range of S11 below 10dB is improved by more than 300%.

[0028] 2. The coupling level has been significantly reduced, and the isolation at the center frequency band has been improved by more than 30dB.

[0029] 3. The axial ratio bandwidth of the circular polarization is widened, and the mismatch between the initial axial ratio of the circular polarization array and the impedance matching frequency band offset is corrected.

[0030] 4. The envelope correlation coefficient of the circularly polarized antenna array decreases significantly, tending to 0 overall, and the radiation pattern is uncorrelated.

[0031] 5. The radiation efficiency of the antenna is improved after loading the metasurface. Attached Figure Description

[0032] Figure 1 A schematic diagram of a microstrip circularly polarized antenna array with a metasurface covering structure is provided as an example of the present invention.

[0033] Figure 2 for Figure 1 A schematic diagram of the upper metal structure of the surface covering structure of the Chinese Super League.

[0034] Figure 3 for Figure 1 A schematic diagram of the lower metal structure of the surface covering structure of the Chinese Super League.

[0035] Figure 4 for Figure 1 A schematic diagram of the metal patch layer structure of a circularly polarized antenna array.

[0036] Figure 5 for Figure 1 A parameter comparison diagram of a circularly polarized antenna array, in which... Figure 5 (a) Figure 5 (b) are schematic diagrams of simulated S-parameters of the microstrip circularly polarized antenna array with and without a metasurface provided in the example of the present invention.

[0037] Figure 6 A schematic diagram of the simulated axial ratio of a microstrip circularly polarized antenna array before and after loading a metasurface covering structure, provided as an example of the present invention.

[0038] Figure 7 A schematic diagram of the envelope correlation coefficients of a microstrip circularly polarized antenna array before and after loading a metasurface covering structure, provided as an example of the present invention.

[0039] Figure 8 A schematic diagram illustrating the radiation efficiency of a microstrip circularly polarized antenna array before and after loading a metasurface covering structure, as provided in this invention example. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] It should be noted that when a component is said to be "installed on" another component, it can be directly on the other component or it may be in a component that is centered on it. When a component is said to be "set on" another component, it can be directly set on the other component or it may also be in a component that is centered on it. When a component is said to be "fixed to" another component, it can be directly fixed to the other component or it may also be in a component that is centered on it.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "or / and" as used herein includes any and all combinations of one or more of the associated listed items.

[0043] The microstrip circularly polarized antenna array of the present invention has a metasurface covering structure, such as Figure 1 As shown, a metasurface covering structure is mounted above the circularly polarized antenna array, meaning the metasurface covering is placed directly above the microstrip circularly polarized antenna array. An air layer with a height of 6.5 mm is designed between the metasurface covering structure and the circularly polarized antenna array. The basic principle of this invention is to introduce an indirect coupling field between adjacent antennas, which cancels out the original coupling field, achieving decoupling. The metasurface covering structure can be fixed above the circularly polarized antenna array by multiple support structures 7, such as nylon struts.

[0044] The metasurface covering structure includes an insulating dielectric layer 2 and an upper metal array and a lower metal array fixed on opposite sides of the insulating dielectric layer 2, with the lower metal array facing the circularly polarized antenna array. The elements of the upper and lower metal arrays not only correspond in number, but also in their positions on the upper and lower opposite sides of the insulating dielectric layer 2.

[0045] Please combine Figure 2 The upper metal array comprises multiple upper metals 1 arranged in a layered array, with a spacing of 10 mm between adjacent upper metals 1. In this embodiment, the multiple upper metals 1 are 15 basic units arranged in a 3-row, 5-column periodic pattern, with a periodic interval of 10 mm between the units.

[0046] Each upper metal layer 1 has two horizontal slits 11, two vertical slits 12, and one intermediate slit 13. The two horizontal slits 11 extend through opposite ends of the corresponding upper metal layer 1 in the horizontal direction, and the two vertical slits 12 extend through opposite ends of the corresponding upper metal layer 1 in the vertical direction. The intermediate slit 13 is located between and parallel to the two vertical slits 12. Both ends of the intermediate slit 13 pass through the two horizontal slits 11, but the length of the intermediate slit 13 is less than the length of the two vertical slits 12. Each upper metal layer 1 is square, and the two horizontal slits 11 and the two vertical slits 12 have the same width. The width of the two transverse gaps 11, the distance between the center of the two transverse gaps 11 and the corresponding upper metal 1, the width of the two longitudinal gaps 12, the distance between the center of the two longitudinal gaps 12 and the corresponding upper metal 1, the length of the middle gap 13, the width of the middle gap 13, and the ratio of the side length of the corresponding upper metal 1 are 0.4mm∶1.6mm∶0.2mm∶2.3mm∶6.4mm∶0.4mm∶8.4mm.

[0047] In this embodiment, the upper metal layer 1 is formed by etching horizontal and vertical slots on a square patch with a side length of 8.4 mm. The two horizontal slots 11 are identical, with a width of 0.4 mm and a center distance of 1.6 mm. The two vertical slots 12 on the left and right are identical, with a width of 0.2 mm and a center distance of 2.3 mm. The middle vertical slot, i.e., the middle slot 13, has a length of 6.4 mm and a width of 0.4 mm.

[0048] The lower metal array comprises multiple lower metals 3 arranged in a layered array, with each lower metal 3 corresponding one-to-one with the position of the multiple upper metals 1 on the insulating dielectric layer 2. That is, in this embodiment, the multiple lower metals 3 are 15 basic units arranged in a 3-row, 5-column periodic pattern, with a periodic interval of 10 mm between the units.

[0049] Please combine Figure 3 Each lower metal layer 3 is shaped like an inclined cross. The major axis of each lower metal layer 3 is formed by etching away two equilateral right triangles with a side length of B mm from a positively oriented patch with a side length of A mm. The minor axis of each lower metal layer 3 is formed by etching away two equilateral right triangles with a side length of D mm from a positively oriented patch with a side length of C mm. The ratio of A:B:C:D is 5.6:4.4:3.6:2.8.

[0050] In this embodiment, the major axis of each lower metal layer 3 is formed by etching away two diagonally opposite equilateral right triangles with a side length of 4.4mm from a positively oriented patch with a side length of 5.6mm. The minor axis of each lower metal layer 3 is formed by etching away two diagonally opposite equilateral right triangles with a side length of 2.8mm from a positively oriented patch with a side length of 3.6mm.

[0051] The metasurface dielectric layer, i.e., insulating dielectric layer 2, has a dielectric constant of 4.4, a thickness of 1.5 mm, a length of 60 mm, and a width of 40 mm, and is made of FR4.

[0052] Please combine Figure 4 The circularly polarized antenna array includes a second insulating dielectric layer 5, two metal patches 4, and a metal ground layer 6. The second insulating dielectric layer 5 is located below the first insulating dielectric layer 2; the two metal patches 4 are fixed to the side of the second insulating dielectric layer 5 facing the first insulating dielectric layer 2; the metal ground layer 6 is laid flat and fixed to the opposite side of the second insulating dielectric layer 5 facing away from the first insulating dielectric layer 2. The second insulating dielectric layer 5 has a dielectric constant of 4.4, a thickness of 1.5 mm, a length of 60 mm, and a width of 40 mm, and is made of FR4.

[0053] Two metal patches 4 are symmetrical about the insulating dielectric layer 5 and are respectively provided with coaxial power supply structures; each metal patch 4 is an equilateral right triangle with a side length of E mm etched diagonally F mm in the positive direction, and the distance between the sides of the metal patch is G mm; E:F:G is 14:4:3.

[0054] In this embodiment, the metal patch of the microstrip circularly polarized array includes two metal patches, designed to be symmetrical about the center of the substrate, each with a coaxial feed structure. The metal patch is a 4mm equilateral right-angled triangle etched diagonally in the positive direction with a side length of 14mm (in contrast, the metal patch before decoupling was a 2.8mm equilateral right-angled triangle etched diagonally in the positive direction with a side length of 13.4mm). The distance between the edges of the metal patches is 3mm.

[0055] M3 through-holes are designed at the four corners of the metasurface cladding and the antenna array layer (i.e., the four corners of insulating dielectric layer 2 and insulating dielectric layer 5), corresponding vertically. The support structure is designed as nylon struts. The nylon struts are installed at the through-hole positions to separate the metasurface cladding and the antenna array layer.

[0056] The circularly polarized antenna array of the present invention is fabricated by means of the following steps.

[0057] First, a circularly polarized antenna array is designed. A coaxial feeding structure is designed within the antenna array layer of the circularly polarized antenna array, and four M3 vias are symmetrically drilled at the four corners of the antenna array layer, with a distance of 55mm between the vias and a width of 35mm. During the design of the circularly polarized antenna array, a metal patch layer 4 and a metal ground layer 6 are respectively etched on opposite sides of the insulating dielectric layer 5 to form the antenna array layer.

[0058] Secondly, multiple upper metal layers 1 and multiple lower metal layers 3 are respectively etched on opposite sides of the insulating dielectric layer 2.

[0059] Then, symmetrical through holes are drilled around the perimeter of insulating dielectric layer 2, with their positions corresponding to the through holes on insulating dielectric layer 5.

[0060] Finally, install an insulating support structure 7 at each pair of through-hole locations, leaving an air layer 8 with a thickness of 6.5 mm.

[0061] In this embodiment, the specific fabrication method of the circularly polarized antenna array can be described as follows: First, the antenna array layer is designed by etching a metal patch layer 4 and a metal ground layer 6 on top and bottom of an antenna dielectric layer 5 with a thickness of 1.5 mm, a length of 60 mm, and a width of 40 mm. The antenna dielectric layer 5 uses FR4 with a dielectric constant of 4.4. A coaxial feed structure is designed on the antenna array layer, and four M3 vias are symmetrically drilled at the four corners, with a distance of 55 mm between the vias and a width of 35 mm. The metasurface cladding is formed by etching an upper metal layer 1 and a lower metal layer 2 on top and bottom of a metasurface dielectric layer 2 with a thickness of 1.5 mm, a length of 60 mm, and a width of 40 mm. The metasurface dielectric layer 2 uses FR4 with a dielectric constant of 4.4. Symmetrical vias are drilled around the metasurface cladding, with their positions corresponding to the via positions of the antenna array layer. Finally, a nylon pillar support structure 7 is installed at the via positions, leaving an air layer 8. The thickness of the air layer is 6.5 mm.

[0062] The basic principle of this invention is to introduce an indirect coupling field between adjacent antennas, which cancels out the original coupling field, thus achieving decoupling. For example... Figure 5 a, Figure 5 A comparison of the S-parameters of b shows that the decoupling method of this invention can both broaden the impedance matching frequency and reduce the coupling value, improving the isolation by more than 30dB at the center frequency band. For example... Figure 6 A comparison of the axial ratio parameters shows that the design method can broaden the axial ratio bandwidth of circular polarization. Besides improved port performance isolation, a good metasurface coating can improve antenna radiation performance. For example... Figure 7 As shown, after loading the metasurface, the envelope correlation coefficient of the circularly polarized antenna array tends to 0, and the radiation pattern becomes uncorrelated. Figure 8 As shown, the radiation efficiency of the antenna is improved after loading the metasurface.

[0063] This invention can achieve good decoupling for microstrip circularly polarized antenna arrays with closely spaced edges. In summary, this invention places a metasurface cladding layer directly above the microstrip circularly polarized antenna array. The metasurface cladding layer consists of upper and lower metal layers and a dielectric layer; the described microstrip circularly polarized antenna includes a diagonally etched triangular metal patch layer, an antenna dielectric layer, and a metal ground layer. An air layer is designed between the metasurface cladding layer and the antenna layer, and nylon struts are used to fix the structure.

[0064] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A circularly polarized antenna array, characterized by, An oversurface covering structure is installed above the circularly polarized antenna array, an air layer is designed between the oversurface covering structure and the circularly polarized antenna array, the height of the air layer is 6.5mm; the oversurface covering structure comprises an insulating dielectric layer one (2) and an upper metal array and a lower metal array fixed on opposite sides of the insulating dielectric layer one (2) respectively, and the lower metal array faces the circularly polarized antenna array; The upper metal array comprises a plurality of upper metals (1) arranged in an array, two transverse slits (11) are formed on each upper metal (1) and penetrate through opposite ends of the upper metal (1) in the transverse direction, two longitudinal slits (12) are formed on each upper metal (1) and penetrate through opposite ends of the upper metal (1) in the longitudinal direction, and a middle slit (13) is formed between the two longitudinal slits (12) and parallel to the two longitudinal slits (12); the two ends of the middle slit (13) penetrate through the two transverse slits (11), but the length of the middle slit (13) is less than the length of the two longitudinal slits (12); The lower metal array comprises a plurality of lower metals (3) arranged in an array, the positions of the plurality of lower metals (3) and the plurality of upper metals (1) on the insulating dielectric layer one (2) correspond to each other; each lower metal (3) is in the shape of an inclined cross; the long axis of each lower metal (3) is formed by a positive patch with a side length of A mm, and the remaining part is formed by etching away two opposite isosceles right triangles with a side length of B mm; the short axis of each lower metal (3) is formed by a positive patch with a side length of C mm, and the remaining part is formed by etching away two opposite isosceles right triangles with a side length of D mm; A:B:C:D is 5.6:4.4:3.6:2.

8.

2. The circularly polarized antenna array of claim 1, wherein, The oversurface covering structure is fixed above the circularly polarized antenna array by a plurality of nylon supports.

3. The circularly polarized antenna array of claim 1, wherein, The interval between adjacent two upper metals (1) is 10mm.

4. The circularly polarized antenna array of claim 1, wherein, Each upper metal (1) is in the shape of a square, the width of the two transverse slits (11) is the same, and the width of the two longitudinal slits (12) is also the same; The width of the two transverse slits (11), the distance between the two transverse slits (11) and the center of the corresponding upper metal (1), the width of the two longitudinal slits (12), the distance between the two longitudinal slits (12) and the center of the corresponding upper metal (1), the length of the middle slit (13), the width of the middle slit (13), and the side length of the corresponding upper metal (1) are in the ratio of 0.4mm:1.6mm:0.2mm:2.3mm:6.4mm:0.4mm:8.4mm.

5. The circularly polarized antenna array of claim 1, wherein, The circularly polarized antenna array comprises: an insulating dielectric layer two (5) located below the insulating dielectric layer one (2); two metal patches (4) fixed on one side of the insulating dielectric layer two (5) facing the insulating dielectric layer one (2); a metal ground layer (6) fixed on the opposite side of the insulating dielectric layer two (5) away from the insulating dielectric layer one (2).

6. The circularly polarized antenna array of claim 5, wherein, The dielectric constant of the insulating medium layer one (2) and the insulating medium layer two (5) is 4.4, and both are made of FR4 and have a thickness of 1.5 mm. The length and width of the two insulating medium layers are the same as the length and width of the circularly polarized antenna array.

7. The circularly polarized antenna array of claim 5, wherein, The two metal patches (4) are symmetric about the center of the insulating medium layer two (5) and are respectively provided with coaxial feeding structures. Each metal patch (4) is an isosceles right triangle with a side length of E mm etched on the diagonal of a positive direction patch with a side length of F mm. The distance between the sides of the metal patch is G mm. E:F:G is 14:4:

3.

8. A method of manufacturing a circularly polarized antenna array as claimed in any one of claims 1 to 7, characterized in that, It comprises the following steps: First, design a circularly polarized antenna array, design a coaxial feeding structure on the antenna array layer of the circularly polarized antenna array, and symmetrically punch four M3 through holes on the four corners of the antenna array layer. The distance between the through holes is 55 mm long and 35 mm wide. A plurality of upper metals (1) and a plurality of lower metals (3) are respectively engraved on the opposite sides of the insulating medium layer one (2). Symmetrically punch through holes around the insulating medium layer one (2), and the positions of the through holes are consistent with the positions of the through holes on the insulating medium layer two (5). An insulating support structure (7) is installed at each pair of through hole positions, leaving an air layer (8) with a thickness of 6.5 mm.

9. The method of claim 8, wherein the method further comprises: When designing a circularly polarized antenna array, metal patch layers (4) and metal ground layers (6) are respectively engraved on the opposite sides of the insulating medium layer two (5) to form the antenna array layer.

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