Circularly polarized wide-beam scanning array unit

Abstract

The invention discloses a circularly polarized wide-beam scanning array unit, the bottom layer of the array unit is provided with a second layer of metal floor, the second layer of metal floor is provided with a feed structure and a radiation structure from bottom to top in sequence, and the peripheral surfaces of the feed structure and the radiation structure are coated with isolation structures. A sequentially rotating coupling feed strip line is clamped in the feed structure, a second layer of metasurface patch is adopted in the radiation structure, and a dielectric covering layer is arranged at the upper end of the radiation structure. The array antenna unit has the advantages of wide frequency band, large circular polarization scanning angle, simple structure, low profile and the like, is suitable for a single-side main plane broadband circular polarization large-angle scanning array antenna, and is particularly suitable for a mixed scanning type high-gain satellite communication ground terminal antenna; and the application in the aspects of a re-frequency selective surface, a polarization selective surface, an intelligent metasurface, a backtracking array and the like can be expanded.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and in particular to a circularly polarized wide-beam scanning array unit. Background Technology

[0002] In the field of satellite communications, high-gain antennas with good directionality and beam scanning capabilities are typically required to address the limitations imposed by long communication distances and complex space environments. With the successful deployment of low-Earth orbit satellite communication systems, there is a surge in demand for high-performance antennas used in satellite communication ground terminal equipment.

[0003] Currently, based on the method of antenna beam scanning capability, antennas are mainly classified into mechanical scanning, electronically controlled scanning, and hybrid scanning types. Among them, hybrid scanning high-gain antennas are the mainstream application form for ground terminal equipment, and their main representative is the CTS (Continuous Transverse Stub) array antenna based on PCB (printed circuit board) technology. This type adopts a hybrid mechanical and electronically controlled scanning method in the elevation and azimuth directions, combining the advantages of mechanical and electronically controlled scanning high-gain antennas. While ensuring that the antenna has the characteristics of low profile, light weight, and high functionality, it reduces the antenna design difficulty and manufacturing cost.

[0004] However, facing the demands of next-generation low-Earth orbit satellite communication applications, even with hybrid scanning high-gain antennas, the simultaneous achievement of the three major operating characteristics—wide bandwidth, wide scanning angle, and circular polarization—places even higher requirements on antenna design. The core of array antenna design is the antenna element, which directly determines the antenna's performance. In current array antenna element designs, to ensure that each element possesses all three performance characteristics, complex inter-board structures are typically employed, inevitably increasing design costs and reducing stability. Alternatively, a compromise strategy of sacrificing one performance characteristic is used to meet the basic requirements of the majority of antenna performance. Both approaches contradict the trend of large-scale application development of satellite communication ground terminal antennas, necessitating innovative methods to improve and enhance array element performance. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a circularly polarized wide-beam scanning array unit, which aims to solve the problem that the array antennas in the prior art usually adopt a complex inter-board unit structure, which leads to reduced stability and cannot simultaneously meet the three major operating characteristics of wide bandwidth, wide scanning angle and circular polarization.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, a circularly polarized wide-beam scanning array unit is provided. The bottom layer of the array unit is configured as a second metal ground plane. From bottom to top, a feeding structure and a radiating structure are provided on the second metal ground plane. The outer periphery of the feeding structure and the radiating structure is covered by an isolation structure. A sequentially rotated coupled feeding stripline is sandwiched in the feeding structure. A second metasurface patch is used in the radiating structure, and a dielectric covering layer is provided at the upper end of the radiating structure.

[0007] Furthermore, the dielectric covering layer adopts a perforated dielectric covering layer, which consists of two narrow transverse beams, two wide transverse beams, and two narrow longitudinal beams. The two narrow transverse beams intersect with the two narrow longitudinal beams to form a grid pattern. The two wide transverse beams are placed on both sides of the narrow longitudinal beams, and the perforated dielectric covering layer is attached to the upper end of the radiating structure through the first adhesive layer.

[0008] Furthermore, the radiation structure is a multi-layer structure, including a first layer of cross-slit radiating patch, a first layer of dielectric substrate, a second layer of metasurface patch, a second layer of adhesive layer, and a second layer of dielectric substrate arranged sequentially from top to bottom, with a power feeding structure provided below the second layer of dielectric substrate.

[0009] Furthermore, the first layer of cross-slit segmented radiation patch consists of two square patches in the diagonal direction and two chamfered square patches in the anti-diagonal direction. The four patches are separated by transverse and longitudinal slits. The first layer of cross-slit segmented radiation patch radiates in a quasi-magnetic dipole mode and optimizes the circular polarization performance by utilizing the two chamfers in the anti-diagonal direction.

[0010] Furthermore, the second metasurface patch consists of 16 sub-period-sized square patches, which are equidistantly divided by three transverse slits and three longitudinal slits and arranged in a 4×4 array.

[0011] Furthermore, the power supply structure consists of a first metal floor, a third adhesive layer, a sequentially rotated coupling power supply strip, and a third dielectric substrate, arranged from top to bottom. A cross-shaped coupling seam is provided on the first metal floor.

[0012] Furthermore, the cross-shaped coupling seam is formed by the intersection of a horizontal seam and a vertical seam, and the intersection is located at the exact center of the first layer of metal floor. The direction of the cross-shaped coupling seam is the same as the direction of the seams of the first layer of cross-shaped seam dividing the radiation patch and the second layer of metasurface patch in the radiation structure.

[0013] Furthermore, the sequentially rotated coupled feed stripline is composed of a feed input line, an impedance matching line, a first feed point, a first phase delay line, a second feed point, a second phase delay line, a third feed point, a third phase delay line, a fourth feed point, and an open-circuit stub connected in sequence. The wiring of the sequentially rotated coupled feed stripline is in a counterclockwise sequential rotation form. The stripline feed line passes through a cross-shaped coupling seam on the first metal floor and is fed at four feed points in a slot coupling form, forming a relative phase delay pattern of 0°, 90°, 180°, and 270° to achieve circular polarization operation.

[0014] Furthermore, the isolation structure includes a first layer of annular metal sheet, a second layer of annular metal sheet, and multiple metal pillars. The first layer of annular metal sheet is on the same layer as the first layer of cross-slit radiating patch in the radiating structure. The second layer of annular metal sheet is on the same layer as the second layer of metasurface patch in the radiating structure. The multiple metal pillars surround the radiating structure and the feeding structure, and their arrangement interval is one-sixth of the array unit period length. They connect the outer sides of the first layer of annular metal sheet and the second layer of annular metal sheet. The bottom end of the metal pillars is connected to the second layer of metal floor.

[0015] The second aspect is the application of a circularly polarized wide-beam scanning array unit in array antennas, frequency selective surfaces, polarization selective surfaces, smart metasurfaces, and backtracking arrays. The array antennas include reflective array antennas and transmission array antennas.

[0016] The technical solution adopted in this invention has the following beneficial effects: The circularly polarized wide-beam scanning array unit of this invention consists of four dielectric substrates, four metal layers, and metal pillars in terms of interlayer structure. It has no air gaps, allowing for complete fabrication using PCB technology. Furthermore, it features a low profile, simple structure, and stable performance. Functionally, a perforated dielectric overlay layer is used on the top of the unit to improve scanning polarization purity and increase the circular polarization scanning angle. A metasurface patch layer is used between the radiating patch layer and the metal ground plane to significantly improve the active reflection coefficient bandwidth and circular polarization scanning stability. A sequential rotating stripline slot coupling feeding method further enhances the unit's broadband circular polarization stability.

[0017] This array antenna element has many advantages such as wide bandwidth, large circular polarization scanning angle, simple structure, and low profile. It is suitable for single-sided main plane broadband circular polarization large-angle scanning array antennas, and is especially suitable for hybrid scanning type high-gain satellite communication ground terminal antennas. Attached Figure Description

[0018] Figure 1 A schematic diagram of a circularly polarized wide-beam scanning array unit structure (placed in the array); Figure 2Exploded view of the unit structure of a circularly polarized wide-beam scanning array; Figure 3 A schematic diagram of the top-layer perforated medium covering layer; Figure 4 A schematic diagram of a cross-shaped slit segmented radial patch with beveled edges; Figure 5 This is a schematic diagram of a metasurface patch; Figure 6 A schematic diagram of a metal floor with a cross-shaped coupling joint; Figure 7 This is a schematic diagram of a sequentially rotated coupled feed stripline. Figure 8 This is a schematic diagram of the isolation structure. Figure 9 The results of the active reflection coefficient of the unit at elevation angles of 0°, 15°, 30°, 45°, and 60° in a specific embodiment of the present invention; Figure 10 The unit axis ratio results are for pitch angles of 0°, 15°, 30°, 45°, and 60° in specific embodiments of the present invention.

[0019] 10. Array unit; 100. Dielectric capping layer; 101. Hollowed-out dielectric capping layer; 1011. Narrow horizontal beam; 1012. Wide horizontal beam; 1013. Narrow vertical beam; 102. First adhesive layer; 200. Radial structure; 201. First layer cross-slit segmented radial patch; 2011. Square patch; 2012. Chamfered square patch; 2013. Chamfer; 2014. Horizontal slot; 2015. Vertical slot; 202. First dielectric substrate; 203. Second metasurface patch; 2031. Sub-periodic size square patch; 2032. Horizontal slot; 2033. Vertical slot; 204. Second adhesive layer; 205. Second dielectric substrate; 300. Feed structure; 301. Cross-shaped coupling 3011, Horizontal seam; 3012, Vertical seam; 302, First metal ground plane; 303, Third adhesive layer; 304, Sequentially rotated coupled feed strip; 3041, Feed input line; 3042, Impedance matching line; 30431, First feed point; 30441, First phase delay line; 30432, Second feed point; 30442, Second phase delay line; 30433, Third feed point; 30443, Third phase delay line; 30434, Fourth feed point; 3045, Open circuit stub; 305, Third dielectric substrate; 400, Isolation structure; 401, First annular metal sheet; 402, Second annular metal sheet; 403, Metal pillar; 404, Second metal ground plane. Detailed Implementation

[0020] To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0021] like Figure 1 The diagram shows a schematic of the circularly polarized wide-beam scanning array unit 10 of the present invention (placed in an array). The array unit is arranged in a square (marked by dashed lines in the figure), including a dielectric cover layer 100, a radiating structure 200, a feeding structure 300, and an isolation structure 400. The bottom layer of the array unit 10 is a second metal ground plane 404. The feeding structure 300 and the radiating structure 200 are arranged sequentially from bottom to top on the second metal ground plane 404. The outer periphery of the feeding structure 300 and the radiating structure 200 is covered by the isolation structure 400. The feeding structure 300 is sandwiched with a sequentially rotated coupled feeding stripline 304. The radiating structure 200 uses a second metasurface patch 203, and the upper end of the radiating structure 200 is provided with a dielectric cover layer 100.

[0022] like Figure 2 The figure shown is an exploded view of the structure of the circularly polarized wide-beam scanning array unit 10 of the present invention.

[0023] The medium cover layer 100 includes, from top to bottom, a first perforated medium cover layer 101 and a first adhesive layer 102.

[0024] The radiation structure 200 includes, from top to bottom, a first layer of cross-slit radiating patch 201, a first layer of dielectric substrate 202, a second layer of metasurface patch 203, a second layer of adhesive layer 204, a second layer of dielectric substrate 205, and below the second layer of dielectric substrate 205 is a first layer of metal floor 302. The power supply structure 300 includes a cross-shaped coupling seam 301 on a first metal floor 302, below which is a third adhesive layer 303, a sequentially rotated coupling power supply strip 304, a third dielectric substrate 305, and below the third dielectric substrate 305 is a second metal floor 404. The isolation structure 400 includes a first layer of annular metal sheet 401, a second layer of annular metal sheet 402, and a metal pillar 403. The first layer of annular metal sheet 401 is on the same layer as the first layer of cross-slit radiating patch 201. The second layer of annular metal sheet 402 is on the same layer 203 as the second layer of metasurface patch. The metal pillar 403 surrounds the entire unit 10 structure and is connected from the first layer of annular metal sheet 401 to the bottom layer of the second metal floor 404.

[0025] In one embodiment of the present invention, such as Figure 3The diagram shows a schematic of the top-layer perforated dielectric cover layer of the present invention. The top-layer perforated dielectric cover layer 101 of the array unit 10 is composed of two narrow horizontal beams 1011, two wide horizontal beams 1012, and two narrow vertical beams 1013. The two narrow horizontal beams 1011 and the two narrow vertical beams 1013 intersect, forming a grid pattern. The two wide horizontal beams 1012 are positioned on the upper and lower sides of the narrow vertical beams 1013. The perforated dielectric cover layer 101 generates different phase shifts for polarized waves in the X1 and Y1 directions. Especially during large-angle scanning, it can maintain the phase difference between the polarized waves in the X1 and Y1 directions at around 90° over a wide frequency band, achieving wide-angle circular polarization scanning on a single-sided main plane. Simultaneously, the grid-like structure ensures the basic structural strength of the perforated dielectric cover layer 101 during subsequent use.

[0026] In one embodiment of the present invention, such as Figure 4 The diagram shows a schematic of the cross-slit radiating patch with chamfered corners according to the present invention. The first layer of the cross-slit radiating patch 201 consists of two square patches 2011 diagonally and two chamfered square patches 2012 anti-diagonally, with the four patches separated by a transverse slit 2014 and a longitudinal slit 2015. The cross-slit radiating patch 201 radiates in a quasi-magnetic-electric dipole mode, where the four patches are paired in pairs to operate in electric dipole mode, and the cross slits operate in magnetic dipole mode, enhancing the omnidirectionality of the unit radiation pattern in the key radiation area. By utilizing the two chamfered corners 2013 anti-diagonal of the chamfered square patches 2012, the resonant frequencies of the cross-slit radiating patch 201 in the X1 and Y1 directions are finely adjusted, and combined with the sequentially rotated coupled feed stripline 304, the circular polarization performance is jointly optimized.

[0027] In one embodiment of the present invention, such as Figure 5 The diagram shows a schematic of the metasurface patch of the present invention. The second metasurface patch 203 consists of 16 sub-periodic sized square patches 2031, which are equidistantly divided by three transverse slits 2032 and three longitudinal slits 2033. The multimode operation of the second metasurface patch 203 significantly improves the impedance matching characteristics of the cross-slit segmented radiation patch 201 and can greatly enhance the fault tolerance in the actual processing, so as to achieve stable broadband operation and circular polarization wide-angle scanning capability.

[0028] In one embodiment of the present invention, such as Figure 6As shown, the cross-shaped coupling seam 301 of the present invention is formed by the intersection of a horizontal seam 3011 and a vertical seam 3012, located at the center of the first layer metal floor 302. The direction of the seam of the cross-shaped coupling seam 301 is the same as the direction of the seam of the first layer cross-slit radiating patch 201 and the second layer metasurface patch 203. It can be optimized to cooperate with the two chamfered square patches 2012 on the first layer cross-slit radiating patch 201 to achieve efficient circular polarization coupling power feeding.

[0029] In one embodiment of the present invention, such as Figure 7 The diagram shows a schematic of the sequentially rotated coupled feed stripline of the present invention. The sequentially rotated coupled feed stripline 304 consists of a feed input line 3041, an impedance matching line 3042, a first feed point 30431, a first phase delay line 30441, a second feed point 30432, a second phase delay line 30442, a third feed point 30433, a third phase delay line 30443, a fourth feed point 30434, and an open-circuit stub 3045. Its wiring pattern is a counter-clockwise sequential rotation. The sequentially rotated coupled feed stripline 304 is fed through a cross-shaped slot 301 on the metal ground plane 302, using a slot coupling method to achieve four feed points, forming relative phase delay configurations of 0°, 90°, 180°, and 270°, realizing right-hand circular polarization operating characteristics. The power supply method employed in this invention has a simple structure. Compared to the traditional four-feed structure using a power divider, branch line coupler, and 180° ring bridge, it significantly reduces structural complexity and improves performance stability. The sequentially rotating coupled feed stripline 304 can change its rotation direction according to actual usage requirements. If a clockwise direction is adopted, right-hand circular polarization operating characteristics can be achieved (not shown). The feed input line 3041 can be used in a vertical interconnect structure (not shown) or a BGA (ball grid array) form (not shown) for cross-layer feed connections, depending on actual usage requirements.

[0030] In one embodiment of the present invention, such as Figure 8 The diagram shows the isolation structure of the present invention. The isolation structure 400 consists of a first-layer annular metal sheet 401, a second-layer annular metal sheet 402, and metal pillars 403. The first-layer annular metal sheet 401 is on the same layer as the first-layer cross-slit radiating patch 201, and the second-layer annular metal sheet 402 is on the same layer 203 as the second-layer metasurface patch. The metal pillars 403 surround the entire array unit 10 structure, connecting from the first-layer annular metal sheet 401 to the bottommost second-layer metal floor 404. The isolation metal pillars 403 are spaced at intervals one-sixth of the unit period length, and are used in conjunction with the first-layer annular metal sheet 401 and the second-layer annular metal sheet 402 to form a cage-like enclosure structure, reducing the coupling strength between units and improving wide-angle scanning performance. In use, each unit 10 shares the isolation structure with surrounding units, such as... Figure 1 As shown.

[0031] In one embodiment of the present invention, the first perforated dielectric cover layer 101, the first dielectric substrate 202, the second dielectric substrate 205, and the third dielectric substrate 305 are made of a domestically produced polytetrafluoroethylene copper-clad laminate with a relative permittivity of 3.5. The first adhesive layer 102, the second adhesive layer 204, and the third adhesive layer 303 are made of a domestically produced prepreg with a relative permittivity of 3.5. The third adhesive layer 303 uses a three-layer prepreg (each prepreg layer is 0.1 mm thick), reducing the number of copper-clad laminates used and lowering processing costs.

[0032] like Figure 9 The image shows the active reflection coefficient results of the unit at elevation angles of 0°, 15°, 30°, 45°, and 60° in a specific embodiment of the present invention. The array unit 10 possesses wide bandwidth and wide-angle radiation characteristics; the maximum elevation angle for scanning a single main plane (X1 direction) can reach 60°. Within the frequency range of 13GHz to 15.6GHz, the active reflection coefficient is below -10dB, and the relative bandwidth is better than 17%.

[0033] like Figure 10 The diagram shows the unit axial ratio results at elevation angles of 0°, 15°, 30°, 45°, and 60° in a specific embodiment of the present invention. The array unit 10 possesses wide bandwidth and angular circular polarization radiation characteristics. The maximum elevation angle for scanning a single principal plane (X1 direction) can reach 60°. The 3dB axial ratio bandwidth covers the frequency range of 13.85GHz to 14.55GHz, which is better than 5%; the 4.5dB axial ratio bandwidth covers the frequency range of 13.7GHz to 14.8GHz, which is better than 7%.

[0034] In summary, the array unit 10 of this invention has many advantages, such as wide bandwidth, large circular polarization scanning angle, simple structure, and low profile, making it suitable for use in single-sided main plane broadband circular polarization large-angle scanning array antennas, especially for hybrid scanning high-gain satellite communication ground terminal antennas. Furthermore, the circular polarization wide-beam scanning array unit 10 can also meet the application requirements of other array antennas (including reflective array antennas and transmissive array antennas), frequency selective surfaces, polarization selective surfaces, smart metasurfaces, and backtracking arrays.

Claims

1. A circularly polarized wide-beam scanning array unit, characterized in that, The bottom layer of the array unit (10) is set as a second metal floor (404). The second metal floor (404) is provided with a feeding structure (300) and a radiation structure (200) from bottom to top. The outer periphery of the feeding structure (300) and the radiation structure (200) is covered with an isolation structure (400). The feeding structure (300) is sandwiched with a sequentially rotated coupling feeding strip (304). The radiation structure (200) uses a second metasurface patch (203), and the upper end of the radiation structure (200) is provided with a dielectric cover layer (100).

2. The circularly polarized wide-beam scanning array unit according to claim 1, characterized in that, The medium cover layer (100) adopts a hollow medium cover layer (101). The hollow medium cover layer (101) is composed of two narrow transverse beams (1011), two wide transverse beams (1012) and two narrow longitudinal beams (1013). The two narrow transverse beams (1011) and the two narrow longitudinal beams (1013) intersect to form a grid. The two wide transverse beams (1012) are placed on both sides of the narrow longitudinal beams (1013). The hollow medium cover layer (101) is attached to the upper end of the radiation structure (200) through the first adhesive layer (102).

3. The circularly polarized wide-beam scanning array unit according to claim 1, characterized in that, The radiation structure (200) is a multi-layer structure, including a first layer of cross-slit radiating patch (201), a first layer of dielectric substrate (202), a second layer of metasurface patch (203), a second layer of adhesive layer (204), and a second layer of dielectric substrate (205) arranged from top to bottom. A power feeding structure (300) is provided below the second layer of dielectric substrate (205).

4. The circularly polarized wide-beam scanning array unit according to claim 3, characterized in that, The first-layer cross-slit radiating patch (201) consists of two square patches (2011) in the diagonal direction and two chamfered square patches (2012) in the anti-diagonal direction. The four patches are separated by a transverse slit (2014) and a longitudinal slit (2015). The first-layer cross-slit radiating patch (201) radiates in a quasi-magnetic dipole mode. The circular polarization performance is optimized by utilizing the two chamfered corners (2013) in the anti-diagonal direction on the chamfered square patch (2012).

5. The circularly polarized wide-beam scanning array unit according to claim 1, characterized in that, The second metasurface patch (203) consists of 16 sub-periodic size square patches (2031). The 16 sub-periodic size square patches (2031) are equidistantly divided by three transverse slits (2032) and three longitudinal slits (2033) and arranged in a 4×4 array.

6. The circularly polarized wide-beam scanning array unit according to claim 1, characterized in that, The power supply structure (300) consists of a first metal floor (302), a third adhesive layer (303), a sequentially rotated coupling power supply strip (304), and a third dielectric substrate (305) arranged from top to bottom. The first metal floor (302) has a cross-shaped coupling seam (301).

7. The circularly polarized wide-beam scanning array unit according to claim 6, characterized in that, The cross-shaped coupling seam (301) is formed by the intersection of a horizontal seam (3011) and a vertical seam (3012), and the intersection is located at the center of the first layer of metal floor (302). The direction of the seam of the cross-shaped coupling seam (301) is the same as the direction of the seam of the first layer of cross-shaped seam dividing radiation patch (201) and the second layer of metasurface patch (203) set in the radiation structure (200).

8. The circularly polarized wide-beam scanning array unit according to claim 6, characterized in that, The sequentially rotated coupled feed stripline (304) is composed of a feed input line (3041), an impedance matching line (3042), a first feed point (30431), a first phase delay line (30441), a second feed point (30432), a second phase delay line (30442), a third feed point (30433), a third phase delay line (30443), a fourth feed point (30434), and an open-circuit stub (3045) connected in sequence. The wiring of the sequentially rotated coupled feed stripline (304) is in a counterclockwise sequential rotation form. The stripline feed line (304) is fed through a cross-shaped coupling seam (301) on the first metal floor (302) in a slot coupling form to feed four feed points, forming a relative phase delay pattern of 0°, 90°, 180°, and 270°, and realizing circular polarization operation.

9. The circularly polarized wide-beam scanning array unit according to claim 1, characterized in that, The isolation structure (400) includes a first layer of annular metal sheet (401), a second layer of annular metal sheet (402), and multiple metal pillars (403). The first layer of annular metal sheet (401) is on the same layer as the first layer of cross-slit radiating patch (201) in the radiating structure (200). The second layer of annular metal sheet (402) is on the same layer as the second layer of metasurface patch (203) in the radiating structure (200). Multiple metal pillars (403) surround the radiating structure (200) and the feeding structure (300) and are arranged at intervals of one-sixth of the array unit period length. They connect the outer sides of the first layer of annular metal sheet (401) and the second layer of annular metal sheet (402). The bottom end of the metal pillar (403) is connected to the second layer of metal floor (404).

10. An application of the circularly polarized wide-beam scanning array unit as described in claim 1 in array antennas, frequency-selective surfaces, polarization-selective surfaces, smart metasurfaces, and backtracking arrays, wherein the array antenna includes a reflective array antenna and a transmissive array antenna.

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