Strong-coupling phased-array antenna unit loaded with metasurface structure

Abstract

The invention discloses a strong-coupling phased-array antenna unit loaded with a metasurface structure, belongs to the technical field of antenna engineering, and relates to a strong-coupling phased-array antenna. According to the metasurface structure for improving the wide-angle scanning performance of the strong-coupling phased-array antenna, on the basis of square metal patches which are periodically and uniformly distributed, rectangular patches which are specially distributed and are inconsistent in length and width are introduced, so that a non-uniform metasurface matching layer structure is formed. When the H-plane wide-angle scanning of the strong-coupling phased-array antenna is carried out, the rectangular patch can equivalently play a role of a director, and the impedance change is smoother, so that the H-plane wide-angle scanning performance of the strong-coupling phased-array antenna is remarkably improved. Meanwhile, the metasurface structure has small influence on the wide-angle scanning performance of the E plane, so that the antenna can achieve good wide-angle scanning performance in both the E plane and the H plane. The metasurface is simple in structure and has the advantages of being single-layer, light in weight and easy to process.

Description

Technical Field

[0001] The present invention belongs to the technical field of antenna engineering, relates to a strongly coupled phased array antenna, and particularly relates to a metasurface structure for improving the wide-angle scanning performance of a strongly coupled phased array antenna, which has the characteristics of light weight, simple structure and easy processing. Background Art

[0002] Broadband phased array antennas have the characteristics of multi-band coverage, high gain and directivity, flexible beam pointing, and anti-interference, and are widely used in base station antennas, spaceborne antennas, airborne antennas and other aspects in the fields of communication and radar. Common forms of broadband phased array antennas include helical antennas, Vivaldi antennas, strongly coupled antennas, etc. Among them, strongly coupled antennas have significant advantages in simultaneously achieving broadband, wide-angle scanning, low profile and other performances compared with other antenna forms.

[0003] When a strongly coupled phased array antenna performs wide-angle scanning, the port scanning impedance changes greatly. Specifically, the impedance decreases with the increase of the scanning angle in the E-plane, and the impedance increases with the increase of the scanning angle in the H-plane, so that the antenna impedance matching performance deteriorates seriously. Therefore, it is necessary to load a wide-angle scanning matching layer above the antenna to improve the impedance matching during wide-angle scanning. The traditional wide-angle scanning matching layer is composed of one or more layers of thick dielectric blocks with different relative dielectric constants, and has the disadvantages of large volume and heavy weight. By printing periodic metal patches on a thin dielectric substrate to form a metasurface matching layer, the traditional dielectric matching layer can be replaced to achieve a thinner design. In the paper "Connected-Slot Array With Artificial Dielectrics: A 6 to 15GHz Dual-Pol Wide-Scan Prototype", a 6-layer metasurface matching layer is adopted, and each layer of the metasurface matching layer is composed of periodic square patches with different patch sizes between different layers, and finally wide-angle scanning is achieved. However, this will lead to complex antenna structure and increase the overall structural weight, which is not conducive to the design and processing of the antenna. Therefore, designing a single-layer, light-weight, simple-structured and easy-to-process metasurface matching layer structure has certain significance in practical engineering applications. Summary of the Invention

[0004] The purpose of the present invention is to propose a novel metasurface structure for improving the wide-angle scanning performance for a strongly coupled phased array antenna on the basis of the above background art. The metasurface structure has the characteristics of single layer, light weight, simple structure and easy processing, and can be directly loaded above the structure of the strongly coupled phased array antenna to improve the impedance matching performance of the antenna during wide-angle scanning.

[0005] The technical solution of the present invention is as follows: A strongly coupled phased array antenna element loaded with a metasurface structure, the antenna element includes: a metasurface structure and a strongly coupled phased array unit antenna. The metasurface structure is sheet-shaped, and the strongly coupled phased array unit antenna includes a metal emission plate and an antenna layer vertically arranged on the metal reflection plate. The metasurface structure is horizontally arranged above the antenna layer, and the projection line of the antenna layer is the midline of the metasurface structure; the metasurface structure includes: a dielectric substrate and a metal patch layer located on the dielectric substrate, and the metal patch layer is covered with a plurality of square and rectangular metal patches over the entire dielectric substrate.

[0006] Further, the strongly coupled phased array unit antenna includes: a metal reflection plate, a dielectric substrate, and radiation patches located on the dielectric substrate; the radiation patches include two dipoles, two coupling patches, two shorting posts, and a feeding balun; wherein, the dipoles and the coupling patches are respectively located on both sides of the dielectric substrate; the two dipoles are respectively located on the left and right sides of the upper part of one side of the dielectric substrate, and there are gaps left with the left and right edges of the dielectric substrate; the coupling patches are rectangular, and the two coupling patches are respectively located on the left and right sides of the upper part of the other side of the dielectric substrate, and the coupled edges are flush with the edges of the dielectric substrate, and the width of the coupling patch is greater than the width of the gap between the dipole and the edge of the dielectric substrate;

[0007] The feeding balun includes: a slotted metal sheet and a metal feeder. The slotted metal sheet and the dipole are on the same side of the dielectric substrate, and the metal feeder and the coupling patch are on the same side of the dielectric substrate. The slotted metal sheet is rectangular as a whole, covers the lower part of the dielectric substrate, and is connected to the metal reflection plate. A large rectangular slot is opened in the middle of the slotted metal sheet. The length of the large rectangular slot is parallel to the width of the slotted metal sheet, and the length of the large rectangular slot is greater than half of the width of the slotted metal sheet; the upper part of the large rectangular slot is open and the lower part is closed. The upper open position divides the slotted metal sheet into left and right parts, and the left and right parts at the opening are respectively connected to the left and right dipoles through metal sheets; a plurality of small rectangular slots are opened in the left part or the right part of the slotted metal sheet. These small rectangular slots are not connected, but are arranged in an L shape in sequence. One end of the L shape is located at the bottom of the slotted metal sheet, and the other end is located at the upper opening position of the large rectangular slot; the metal feeder is L-shaped, corresponding to the L formed by the arrangement of the small rectangular slots. One end of the metal feeder extends downward from the lower end of the dielectric substrate, passes through the metal reflection plate, and does not contact the metal reflection plate. The other end of the metal feeder is connected to a fan-shaped metal patch; when a plurality of small rectangular slots are located in the left part of the slotted metal sheet, the fan-shaped metal patch is located on the right side of the opening part of the slotted metal sheet, and when a plurality of small rectangular slots are located in the right part of the slotted metal sheet, the fan-shaped metal patch is located on the left side of the opening part of the slotted metal sheet;

[0008] One end of the short - circuit post on the left is connected to the middle of the left dipole, and the other end is connected to the middle of the left part of the slotted metal sheet; one end of the short - circuit post on the right is connected to the middle of the right dipole, and the other end is connected to the middle of the right part of the slotted metal sheet.

[0009] Furthermore, the metal patch layer is obtained by simulating and optimizing different strongly - coupled phased - array unit antennas. The specific method is as follows:

[0010] First, a plurality of square metal patches are evenly arranged on the dielectric substrate. Then, at the four - corner positions of the metal patch layer, two or more adjacent square metal patches are replaced by one or more rectangular patches with inconsistent length and width. The effects of the strongly - coupled phased - array antenna unit with the metasurface structure are simulated in turn, and the combination result with the best effect is selected as the final metal patch layer.

[0011] Furthermore, the two widths of the large rectangular slot opened in the middle of the slotted metal sheet are arc - shaped.

[0012] Furthermore, the final metal patch layer is an axisymmetric structure.

[0013] Furthermore, the gap between the two dipoles gradually increases from bottom to top, and the corresponding sides of each dipole at this place are curved.

[0014] The metasurface structure for improving the wide - angle scanning performance of the strongly - coupled phased - array antenna according to the present invention forms a non - uniform metasurface matching layer structure by introducing rectangular patches with inconsistent length and width in a special distribution on the basis of square metal patches uniformly distributed in a period. When the strongly - coupled phased - array antenna performs wide - angle scanning in the H - plane, the rectangular patches can equivalently act as directors, and make the impedance change more gently, thus significantly improving the wide - angle scanning performance of the strongly - coupled phased - array antenna in the H - plane. At the same time, the metasurface structure described in the present invention has less influence on the wide - angle scanning performance in the E - plane. Therefore, the antenna can achieve good wide - angle scanning performance in both the E / H - planes. This metasurface structure is simple and has the advantages of being single - layer, lightweight and easy to process. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a top view of the metasurface structure according to the present invention. Among them, (a) represents the initial metasurface structure, which is square patches uniformly distributed in a period, and (b) represents a specific implementation example of the metasurface structure according to the present invention. Figure 1 In the structure of (b), structure 1 is a single - layer dielectric substrate, structure 2 is a square metal patch, and structure 3 is a rectangular metal patch.

[0016] Figure 2 It is an example of other forms of the metasurface structure according to the present invention, which can be optimized and applied to other strongly - coupled phased - array antennas.

[0017] Figure 3 To load the strongly coupled phased array antenna element with the metasurface structure described in the specific embodiment of the present invention. Among them, structure 4 is a dipole, structure 5 is a coupling sheet, structure 6 is a shorting post, structure 7 is a feeding balun, structure 8 is a slotted metal sheet of the feeding balun, structure 9 is a metal feeder of the feeding balun, and structure 10 is a metal reflector.

[0018] Figure 4 For the strongly coupled phased array antenna element without loading the metasurface structure and other forms of matching layers, the active VSWR (Voltage Standing Wave Ratio) curve.

[0019] Figure 5 For loading Figure 1 (a) The strongly coupled phased array antenna element with the initial metasurface structure shown, the active VSWR curve.

[0020] Figure 6 For the strongly coupled phased array antenna element with the metasurface structure described in the specific implementation example of the present invention, the active VSWR curve. Detailed implementation

[0021] Next, in conjunction with the accompanying drawings, the technical solution of the present invention will be described in detail, but the protection scope of the present invention is not limited to the described implementation examples.

[0022] A strongly coupled phased array antenna element loaded with a novel metasurface structure is composed of a metasurface structure and a strongly coupled phased array unit antenna. The metasurface structure includes a layer of non-uniformly distributed metal patches and a layer of dielectric substrate, and the strongly coupled phased array unit antenna includes a radiation patch and another layer of dielectric substrate; the non-uniformly distributed metal patches are arranged on one side of the dielectric substrate.

[0023] The non-uniformly distributed metal patches are designed by using a non-uniform design method on the basis of square patches with uniform periodic distribution.

[0024] The non-uniform design method is specifically as follows: A plurality of square metal patches are uniformly arranged on the dielectric substrate, and then at the four corner positions of the metal patch layer, two or more adjacent square metal patches are replaced by one or more rectangular patches with inconsistent length and width.

[0025] The rectangular patches have the characteristics of being longer in the E-plane direction and shorter in the H-plane direction. The size and quantity of the rectangular patches at the four corner positions can be flexibly adjusted, so as to adjust and improve the ability of wide-angle scanning impedance matching.

[0026] In this implementation example, the metasurface structure for improving the wide-angle scanning performance of the strongly coupled phased array antenna is as shown in Figure 1 (b) shown. There are two rectangular metal patches at each of the four corners, and the rest are square patches, forming a patch set. For comparison,Figure 1 Figure (a) shows a square patch metasurface structure with a periodic and uniform distribution. In the implementation example, the dielectric substrate material is a polyimide film with a thickness of 0.05 mm and a relative dielectric constant of 3.5. The metal patches are printed on the dielectric substrate through printed circuit board (PCB) technology. The size of a patch set of the metasurface structure in this implementation example is 30 mm × 30 mm, and the gap width between the metal patches is 0.2 mm.

[0027] Figure 2 Other forms of the metasurface structure described in the present invention are exemplified. By flexibly adjusting the size and number of rectangular patches, the ability to improve the wide-angle scanning impedance matching in the H-plane (XOZ plane) can be adjusted.

[0028] To verify the performance of the metasurface structure proposed in the present invention, a strongly coupled phased array antenna element with a working bandwidth of 2:1 loaded with Figure 1 (b) The metasurface structure is designed. As shown in Figure 3 (a) and (b), it is a schematic diagram of the strongly coupled phased array antenna element. The metasurface structure described in the implementation example of the present invention is directly loaded above the designed strongly coupled phased array unit antenna. The radiation patch of the strongly coupled phased array unit antenna is also printed on a polyimide film with a thickness of 0.05 mm and a relative dielectric constant of 3.5. The lateral size of the antenna element is the same as that of a patch set of the metasurface structure, which is 30 mm × 30 mm. In addition, the profile height of the antenna (the distance from the reflector to the top surface of the metasurface structure) is 19 mm.

[0029] Figure 4 The active standing wave ratio curves of the strongly coupled phased array antenna element without loading the metasurface structure and other forms of matching layers are shown. It can be seen that the standing wave ratio is relatively good during the 60° scan in the E-plane (YOZ plane), and the overall value within the band is less than 2.5; however, the standing wave ratios during broadside radiation and the 60° scan in the H-plane are very poor. Especially during the 60° scan in the H-plane, the standing wave ratio is overall above 5.5.

[0030] Figure 5 The active standing wave ratio curves of the strongly coupled phased array antenna element loaded with the square patch metasurface structure with a periodic and uniform distribution are shown. It can be seen that after loading this metasurface structure, the impedance matching performance during broadside radiation and wide-angle scanning has been improved. The standing wave ratios during broadside radiation and the 60° scan in the E-plane have dropped below 2; however, during the 60° scan in the H-plane, the standing wave ratio within the band is overall poor and still above 3.

[0031] Figure 6The active standing wave ratio curve of the strongly coupled phased array antenna element loaded with the metasurface structure described in the specific embodiment of the present invention is shown. Comparing the first two cases, it can be seen that the impedance matching performance during the 60° scan in the H-plane has been significantly improved, while the influence on the 60° scan performance in the E-plane is relatively small, and the standing wave ratios within the side lobe and the 60° scan bands in the E / H-planes are all below 2.5 as a whole. Therefore, the metasurface structure proposed by the present invention not only has the characteristics of single layer, light weight, simple structure and easy processing, but also can achieve a good effect of improving the wide-angle scanning performance of the strongly coupled phased array antenna.

Claims

1. A strongly coupled phased array antenna unit loaded with a metasurface structure, the antenna unit comprising: A metasurface structure and a strongly coupled phased array unit antenna, wherein the metasurface structure is in the shape of a sheet, and the strongly coupled phased array unit antenna comprises a metal transmitting plate and an antenna layer vertically arranged on a metal reflecting plate, and the metasurface structure is horizontally arranged above the antenna layer, and the projection line of the antenna layer is the midline of the metasurface structure; the metasurface structure comprises: a dielectric substrate and a metal patch layer located on the dielectric substrate, and the metal patch layer is composed of a plurality of square and rectangular metal patches covering the entire dielectric substrate.

2. A strongly coupled phased array antenna unit loaded with a metasurface structure as claimed in claim 1, characterized in that: The strongly coupled phased array unit antenna comprises: a metal reflector, a dielectric substrate, and a radiation patch located on the dielectric substrate; the radiation patch comprises two dipoles, two coupling patches, two short-circuit posts, and a feed balun; wherein the dipole and the coupling patch are respectively located on both sides of the dielectric substrate; the two dipoles are respectively located on the left and right sides of the upper part of one side of the dielectric substrate, and there are gaps between the left and right edges of the dielectric substrate; the coupling patch is rectangular, and the two coupling patches are respectively located on the left and right sides of the upper part of the other side of the dielectric substrate, the coupling edge is flush with the edge of the dielectric substrate, and the width of the coupling patch is greater than the width of the gap between the dipole and the edge of the dielectric substrate; The feeding balun comprises: a slotted metal sheet and a metal feed line, wherein the slotted metal sheet and the dipole are located on the same side of the dielectric substrate, the metal feed line and the coupling sheet are located on the same side of the dielectric substrate, the slotted metal sheet is rectangular as a whole, covers the lower part of the dielectric substrate, and is connected to the metal reflector, a large rectangular groove is opened in the middle of the slotted metal sheet, the length of the large rectangular groove is parallel to the width of the slotted metal sheet, and the length of the large rectangular groove is greater than half of the width of the slotted metal sheet; the large rectangular groove is open at the top and closed at the bottom, and the upper opening position divides the slotted metal sheet into left and right parts, and the left and right parts at the opening are respectively connected to the left and right dipoles through the metal sheet; the left part or the right part of the slotted metal sheet is opened There are a plurality of small rectangular slots, which are not connected, but are arranged in an L shape, one end of the L shape is located at the bottom of the slotted metal sheet, and the other end is located at the upper opening position of the large rectangular slot; the metal feed line is L-shaped, corresponding to the L formed by the small rectangular slots, one end of the metal feed line extends downward from the lower end of the dielectric substrate, passes through the metal reflector, and does not contact the metal reflector, and the other end of the metal feed line is connected to a fan-shaped metal patch; when the plurality of small rectangular slots are located at the left part of the slotted metal sheet, the fan-shaped metal patch is located on the right side of the opening of the slotted metal sheet, and when the plurality of small rectangular slots are located at the right part of the slotted metal sheet, the fan-shaped metal patch is located on the left side of the opening of the slotted metal sheet; One end of the left short-circuit post is connected to the middle of the left dipole, and the other end is connected to the middle of the left part of the slotted metal sheet; one end of the right short-circuit post is connected to the middle of the right dipole, and the other end is connected to the middle of the right part of the slotted metal sheet.

3. The strongly coupled phased array antenna unit loaded with a metasurface structure according to claim 1, characterized in that: The metal patch layer is obtained by simulation optimization based on different strongly coupled phased array unit antennas, and the specific method is as follows: First, multiple square metal patches are evenly arranged on a dielectric substrate. Then, at the four corners of the metal patch layer, two or more adjacent square metal patches are replaced by one or more rectangular patches with inconsistent lengths and widths. The effects of strongly coupled phased array antenna units with metasurface structures are simulated in turn, and the best combination result is selected as the final metal patch layer.

4. A strongly coupled phased array antenna unit loaded with a metasurface structure as claimed in claim 2, characterized in that: The two widths of the large rectangular groove opened in the middle of the grooved metal sheet are arc-shaped.

5. The strongly coupled phased array antenna unit loaded with a metasurface structure as claimed in claim 2, characterized in that: The gap between the two dipoles becomes larger from bottom to top, and the corresponding side of each dipole at this position is a curve.

6. The strongly coupled phased array antenna unit loaded with a metasurface structure as claimed in claim 3, characterized in that: The final metal patch layer is an axisymmetric structure.

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