Ultra-wideband low-profile wide-scanning-angle dual-polarized phased-array antenna

Abstract

The invention provides an ultra-wide-band low-profile wide-scanning-angle dual-polarization phased-array antenna. The antenna comprises a metasurface coating, a radiation layer and a metal floor which are sequentially stacked from top to bottom. The metasurface coating layer comprises a first dielectric plate and a plurality of opening resonance circular ring units which are printed on the upper surface of the first dielectric plate and are periodically arranged; four openings which are uniformly distributed are formed in a circular ring of the opening resonance circular ring unit. The circular ring of the opening resonance circular ring unit on the metasurface coating is split into four parts by the four openings which are uniformly distributed, so that the circular ring does not keep a complete annular structure any more, and when electromagnetic waves act on the antenna, the circular ring prevents induction current from forming continuous annular induction current on the circular ring, so that the electromagnetic waves are prevented from being radiated. The current on the circular ring can be kept in the same direction as the antenna array, and the beam scanning angle is effectively widened. According to the invention, the feed structure composed of the grounding metal through hole and the coaxial connector is used for direct feed, so that the height increase of the profile of the antenna caused by the use of a balun is avoided.

Description

Technical Field

[0001] The present invention belongs to the field of antenna technology and relates to a dual-polarization phased array antenna, and specifically relates to an ultra-wideband, low-profile, wide-scanning-angle dual-polarization phased array antenna, which can be applied to a radar system. Background Art

[0002] Phased array antenna refers to an antenna that changes the shape of the radiation pattern by controlling the feeding phase of the radiating elements in the array antenna. Controlling the phase can change the direction of the maximum value of the antenna radiation pattern to achieve the purpose of beam scanning. The polarization modes of the antenna are divided into linear polarization, circular polarization and elliptical polarization. Among them, the dual-polarized antenna refers to an antenna with both horizontal polarization and vertical polarization in one antenna radiating element. The dual-polarized phased array antenna further enhances the performance of the antenna, so that better results can be obtained in different polarization directions. In the dual-polarized phased array antenna, this fast beam scanning capability can be applied to both horizontally polarized and vertically polarized beams, improving the system's response speed and target search capability.

[0003] Phased array antennas need to have broadband characteristics. Traditional phased array antennas use broadband array units to achieve broadband performance, but the spacing between array units will cause grating lobes, which limits the bandwidth of traditional phased array antennas. Tightly coupled array antennas use the strong coupling effect between antenna units to avoid the generation of grating lobes, expand the bandwidth of the antenna, and achieve ultra-wideband matching. Therefore, phased arrays based on tight coupling effects can achieve broadband characteristics. In addition, in order to adapt to a variety of application scenarios, miniaturized phased array antennas can make these devices more lightweight and flexible, easy to deploy and operate, and the design of phased array antennas is gradually moving towards lightweight and miniaturization.

[0004] The patent application with the application publication number CN11387186A and the name of "A low-profile wide-bandwidth angle two-dimensional scanning dual-polarized phased array antenna and its application" discloses a low-profile wide-bandwidth angle two-dimensional scanning dual-polarized phased array antenna, including a polarized dipole planar array, a metal base plate and a planar printed metasurface; the dual-polarized dipole planar array is placed between the metal base plate and the planar printed metasurface; the metal base plate is parallel to the planar printed metasurface. Based on the tight coupling effect, the invention utilizes rather than suppresses the coupling between units to achieve ultra-wideband characteristics that traditional phased array antennas do not have, and can effectively suppress the grating lobe problem of traditional phased array antennas; on the basis of the tightly coupled array antenna, an integrated Marchand balun and a planar printed metasurface are introduced to further expand the bandwidth and scanning angle range of the phased array antenna, and reduce the profile height of the antenna. Since this invention adopts a square ring metasurface structure, when the electromagnetic wave acts on the antenna, the induced current on it is a continuous ring-shaped induced current, rather than being consistent with the current of the antenna in the desired direction, so that the scanning angle range of the antenna on the E-plane is only 0 to 45°, which affects the further widening of the beam scanning angle. In addition, this invention adopts balun feeding, which results in a higher cross-section of the antenna. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and propose an ultra-wideband, low-profile, wide-scanning-angle dual-polarized phased array antenna, which aims to ensure the ultra-wideband characteristics while widening the beam scanning angle and reducing the profile height.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present invention includes a metasurface coating 1, a radiation layer 2 and a metal floor 3 stacked in sequence from top to bottom; the metasurface coating 1 includes a first dielectric plate 11 and a plurality of open resonant circular ring units 12 printed on its upper surface and arranged periodically; the open resonant circular ring unit 12 has four evenly distributed openings on its circular ring.

[0007] The above antenna, the radiation layer 2, includes a second dielectric plate 21 stacked up and down and a composite dielectric plate layer composed of a third dielectric plate 22, a fourth dielectric plate 23, a fifth dielectric plate 24 and a sixth dielectric plate 25, and two groups of feeding structures 26; the upper surface of the third dielectric plate 22 is printed with two mutually intersecting dipole radiation patches 27; the dipole radiation patch 27 includes a grounded dipole radiation patch 271 and a feeding dipole radiation patch 272; the upper surface of the fourth dielectric plate 23 is located between the two dipole radiation patches A circular coupling patch 28 is printed at the projection position of the film, and the circular coupling patch 28 is connected to the metal floor 3 through two grounding short-circuit columns 29; two pairs of rectangular metal patches 30 are printed on the upper surfaces of the fifth dielectric plate 24 and the sixth dielectric plate 25; the feeding structure 26 includes a grounding metal through hole 261 for connecting a grounded dipole radiation patch 271, a pair of rectangular metal patches and the metal floor 3, and a coaxial connector 262 whose inner conductor is connected to the feeding dipole radiation patch 272 and another pair of rectangular metal patches.

[0008] The above-mentioned antenna, the second dielectric plate 21 and the composite dielectric plate layer, have a plate surface size equal to the specifications of the first dielectric plate 11 and the metal floor 3, wherein the second dielectric plate 21 is made of a dielectric material with a relative dielectric constant of 1, and the metal floor 3 is provided with a through hole for the coaxial connector 262 to pass through.

[0009] In the above antenna, the intersection point of the two dipole radiation patches 27 printed on the upper surface of the third dielectric plate 22 is located on a diagonal line of the third dielectric plate 22 and deviates from the lower right side of the center position of the third dielectric plate 22 .

[0010] In the above antenna, the composite dielectric plate layer is provided with a cylindrical cavity that passes through the third dielectric plate 22, the fourth dielectric plate 23, the fifth dielectric plate 24 and the sixth dielectric plate 25 from top to bottom, and the central axis of the cylindrical cavity is located on the diagonal line where the intersection of the two dipole radiation patches on the third dielectric plate 22 is located.

[0011] In the above antenna, the central axis of the cylindrical cavity is located at the upper left of the diagonal line where the intersection of the two dipole radiation patches deviates from the center of the third dielectric plate 22.

[0012] In the above antenna, the third dielectric plate 22 has two dipole radiation patches 27 printed on its upper surface that cross vertically.

[0013] The above-mentioned antenna, the fed dipole radiation patch 272, includes two composite structures, each composite structure includes an isosceles trapezoidal metal patch and an isosceles triangular metal patch whose bottom edge is spliced ​​with the lower bottom edge of the isosceles trapezoidal metal patch, the vertices of the isosceles triangular metal patches in the two composite structures are arranged opposite to each other, and the connection point between the fed dipole radiation patch 272 and the coaxial connector 262 is located at the upper bottom edge of one of the isosceles trapezoidal metal patches.

[0014] In the above antenna, the center lines of the two grounded short-circuit posts 29 are arranged along the diagonal line where the intersection of the two dipole radiation patches on the third dielectric plate 22 is located.

[0015] In the above antenna, the circular coupling patch 28 has its center located at the projection position of the intersection of the two dipole radiation patches.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] 1. The ring of the open resonant ring unit on the metasurface coating of the present invention is split into four parts by four evenly distributed openings, so that it no longer maintains a complete ring structure. The four openings make the ring structure more symmetrical, and can more stably couple electromagnetically with the antenna at different scanning angles and frequencies, which helps to match the impedance between the antenna and free space. When electromagnetic waves act on the antenna, the ring prevents the induced current from being a continuous ring induced current on it, so that the current on the ring can maintain the same direction as the antenna array. Compared with the prior art, the present invention effectively broadens the angle of beam scanning.

[0018] 2. The present invention uses a feeding structure composed of a grounded metal through hole and a coaxial connector for direct feeding, thereby avoiding an increase in the antenna profile height caused by the use of a balun. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0020] Figure 2 It is a schematic diagram of the structure of the super surface coating of the present invention.

[0021] Figure 3 It is a schematic structural diagram of the radiation layer of the present invention.

[0022] Figure 4 It is a schematic diagram of the structure of the dipole radiation patch of the present invention.

[0023] Figure 5 This is a simulation diagram of the standing wave ratio of the present invention when scanning the E and H planes within the frequency band range of 2 to 20 GHz. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0025] Reference Figure 1 , the present invention comprises a super surface coating 1, a radiation layer 2 and a metal floor 3 which are sequentially stacked from top to bottom;

[0026] Reference Figure 2 , the metasurface coating 1 includes a first dielectric plate 11 and a plurality of open resonant annular units 12 printed on its upper surface and arranged periodically; the open resonant annular unit 12 is provided with four evenly distributed openings on its annular ring. At different scanning angles, such as scanning at 60° in the E plane and 45° in the H plane, since the open resonant annular unit structure is split into four parts, the current path is cut off, which prevents the formation of a circular current, so that the current can maintain the same direction as the antenna array, indicating that the structure has good coupling characteristics with the antenna. This good coupling helps the impedance matching between the antenna and the free space, so that the antenna can maintain good performance during wide-angle scanning, thereby realizing beam wide-angle scanning, and the four openings make the entire annular structure have higher symmetry, which is not only conducive to the performance stability of the antenna at different scanning angles, but also provides potential conditions for designing a dual-polarization structure, because the highly symmetrical structure makes the radiation characteristics of the antenna easier to control and optimize in different polarization directions, thereby realizing a dual-polarization function. When a dielectric covering layer is loaded on top of the tightly coupled dipole unit, the dielectric covering layer can change the electromagnetic field distribution around the antenna, offset the reactance change caused by the metal floor, thereby further widening the bandwidth and expanding the antenna scanning angle. However, the ideal thickness of the dielectric covering layer is one-quarter of the dielectric wavelength corresponding to the center frequency, which results in a higher overall profile of the antenna. Through the equivalent medium theory, the equivalent parameters of the metasurface covering equivalent to the dielectric covering can be extracted. The thickness of the metasurface covering of the present invention is 1.5 mm, which replaces the F4BM22 dielectric plate with a thickness of 2.5 mm and a relative dielectric constant of 2.2, thereby reducing the overall profile of the antenna.

[0027] Reference Figure 3 The radiation layer 2 includes a second dielectric plate 21 stacked up and down, a composite dielectric plate layer composed of a third dielectric plate 22, a fourth dielectric plate 23, a fifth dielectric plate 24 and a sixth dielectric plate 25, and two groups of feeding structures 26. The second dielectric plate 21 is a dielectric plate with a thickness of 1 mm and a relative dielectric constant of 1, and the composite dielectric plate layer is a F4BM22 dielectric plate with a relative dielectric constant ε=2.2 and a loss tangent tanδ=0.0015 of different thicknesses. The second dielectric plate 21 and the composite dielectric plate layer have the same board size as the first dielectric plate 11 and the metal floor 3.

[0028] The upper surface of the third dielectric plate 22 is printed with two intersecting dipole radiation patches 27, and the two dipole radiation patches 27 are vertically intersected to achieve dual polarization. The dipole radiation patch 27 includes a grounded dipole radiation patch 271 and a feeding dipole radiation patch 272; the upper surface of the fourth dielectric plate 23 is printed with a circular coupling patch 28 at the projection position of the two dipole radiation patches, and the circular coupling patch 28 is connected to the metal floor 3 through two ground short-circuit columns 29, and the center of the circle is located at the projection position of the intersection of the two dipole radiation patches, and the two dipole radiation patches completely cover the circular coupling patch.

[0029] The circular coupling patch 28 and the ground short-circuit post 29 form a ridge waveguide structure to move the antenna resonance point out of the band; the upper surfaces of the fifth dielectric plate 24 and the sixth dielectric plate 25 are printed with two pairs of rectangular metal patches 30 to improve the impedance mismatch of the antenna caused by the ground metal through hole 261 and the coaxial connector 262 being too far apart;

[0030] The feeding structure 26 includes a grounded metal through hole 261 for connecting a grounded dipole radiation patch 271, a pair of rectangular metal patches and a metal floor 3, and a coaxial connector 262 for connecting an inner conductor to a feeding dipole radiation patch 272 and another pair of rectangular metal patches. In order to achieve the conversion from unbalanced feeding to balanced feeding, a balun is generally used for feeding, but this will increase the overall cross-section of the antenna. Therefore, the present invention uses coaxial feeding and adds two grounded short-circuit posts 29 to move the common mode resonance caused by unbalanced feeding out of the band.

[0031] The composite dielectric plate layer is provided with a cylindrical cavity that vertically penetrates the third dielectric plate 22, the fourth dielectric plate 23, the fifth dielectric plate 24 and the sixth dielectric plate 25, and the central axis of the cylindrical cavity is located on the diagonal line where the intersection of the two dipole radiation patches on the third dielectric plate 22 is located. The cylindrical cavity is intended to reduce the effective dielectric constant of the dielectric plate, and the radius of the cylindrical cavity is determined by the following formula:

[0032]

[0033] In the formula, ε r,eff is the effective dielectric constant after drilling, ε r is the relative dielectric constant of the medium, R is the radius of the hole, D x and D y are the dimensions of the unit along the X and Y directions respectively.

[0034] Reference Figure 4Each dipole radiation patch includes an isosceles trapezoidal metal patch and an isosceles triangular metal patch whose bottom edge is spliced ​​with the lower bottom edge of the isosceles trapezoidal metal patch, wherein the feeding dipole radiation patch 271 and the grounding dipole radiation patch 272 are respectively connected to the upper bottom edge of the isosceles trapezoidal metal patch with the inner conductor of the coaxial connector 262 and the grounding metal through hole 261.

[0035] The working principle of the present invention is that the antenna feeds the dipole radiation patch 27 of the third dielectric plate 22 through two groups of feeding structures 26, so that the dipole radiation patch 27 radiates outward; in order to improve the impedance matching of the array and not increase the array profile and weight too much, a metasurface coating 1 is used to replace the dielectric coating; the circular coupling patch 28 and the two ground short-circuit posts 28 form a ridge waveguide structure, which can move the common mode resonance point generated by unbalanced feeding out of the working frequency of the antenna. There are two pairs of rectangular patches connected between the ground metal through hole 261 and the coaxial connector 262, which are used to increase coupling, improve the matching of the antenna, and increase the bandwidth.

[0036] The following is a further description of the technical effects of the present invention in conjunction with the simulation results:

[0037] 1. Experimental conditions and contents:

[0038] The simulation software ANSYS Electronics Desktop v.18.2 was used to simulate the relationship between the standing wave ratio and the frequency when the E and H planes were scanned in the frequency band of 2 to 20 GHz. The results are shown in FIG. Figure 5 shown.

[0039] 2. Experimental results analysis:

[0040] Reference Figure 5 , the horizontal axis is the frequency, ranging from 2GHz to 20GHz, and the vertical axis is the standing wave ratio parameter, ranging from 1 to 6, where Figure 5 (a) and Figure 5 (b) are the scanning angles of the E and H surfaces, respectively. It can be seen that Figure 5 The six curves in (a) are the scanning curves of 0°, 30°, 45°, 60°, 70°, and 75° on the E surface. Figure 5 The three curves in (b) are the H-plane scanning curves of 0°, 30°, and 45°, respectively. Compared with the prior art, the present invention ensures ultra-wideband operation when the standing wave ratio is less than 3, and the E-plane scanning angle can reach 0 to ±75°, realizing wide-angle scanning.

Claims

1. An ultra-wideband, low-profile, wide-scanning-angle dual-polarized phased array antenna, comprising a metasurface coating (1), a radiation layer (2), and a metal floor (3) stacked in sequence from top to bottom; the metasurface coating (1) comprises a first dielectric plate (11) and a plurality of open resonant ring units (12) printed on its upper surface and arranged periodically; characterized in that: The open resonant ring unit (12) has four evenly distributed openings arranged on its circular ring.

2. The antenna according to claim 1, characterized in that The radiation layer (2) comprises a second dielectric plate (21) stacked up and down and a composite dielectric plate layer composed of a third dielectric plate (22), a fourth dielectric plate (23), a fifth dielectric plate (24) and a sixth dielectric plate (25), and two groups of feeding structures (26); the upper surface of the third dielectric plate (22) is printed with two mutually intersecting dipole radiation patches (27); the dipole radiation patches (27) comprise a grounded dipole radiation patch (271) and a feeding dipole radiation patch (272); the upper surface of the fourth dielectric plate (23) is located between the two dipole radiation patches. A circular coupling patch (28) is printed at the projection position, and the circular coupling patch (28) is connected to the metal floor (3) via two grounding short-circuit posts (29); two pairs of rectangular metal patches (30) are printed on the upper surfaces of the fifth dielectric plate (24) and the sixth dielectric plate (25); the feeding structure (26) comprises a grounding metal through hole (261) for connecting a grounded dipole radiation patch (271), a pair of rectangular metal patches and the metal floor (3), and a coaxial connector (262) whose inner conductor is connected to the feeding dipole radiation patch (272) and another pair of rectangular metal patches.

3. The antenna according to claim 2, characterized in that: The second dielectric plate (21) and the composite dielectric plate layer have plate surface dimensions equal to those of the first dielectric plate (11) and the metal floor (3), wherein the second dielectric plate (21) is made of a dielectric material with a relative dielectric constant of 1, and the metal floor (3) is provided with a through hole for the coaxial connector (262) to pass through.

4. The antenna according to claim 2, characterized in that: The intersection point of the two dipole radiation patches (27) printed on the upper surface of the third dielectric plate (22) is located on a diagonal line of the third dielectric plate (22) and deviates from the lower right side of the center position of the third dielectric plate (22).

5. The antenna according to claim 4, characterized in that: The composite dielectric plate layer is provided with a cylindrical cavity which passes through the third dielectric plate (22), the fourth dielectric plate (23), the fifth dielectric plate (24) and the sixth dielectric plate (25) from top to bottom, and the central axis of the cylindrical cavity is located on the diagonal line where the intersection of the two dipole radiation patches on the third dielectric plate (22) is located.

6. The antenna according to claim 5, characterized in that The central axis of the cylindrical cavity is located at the upper left of the diagonal line where the intersection of the two dipole radiation patches deviates from the center of the third dielectric plate (22).

7. The antenna according to claim 2, characterized in that: The third dielectric plate (22) has two dipole radiation patches (27) printed on its upper surface that cross vertically.

8. The antenna according to claim 2, characterized in that: The feed dipole radiation patch (272) comprises two composite structures, each composite structure comprising an isosceles trapezoidal metal patch and an isosceles triangular metal patch whose bottom edge is spliced ​​with the lower bottom edge of the isosceles trapezoidal metal patch, the vertices of the isosceles triangular metal patches in the two composite structures are arranged opposite to each other, and the connection point between the feed dipole radiation patch (272) and the coaxial connector (262) is located at the upper bottom edge of one of the isosceles trapezoidal metal patches.

9. The antenna according to claim 2, characterized in that: The center lines of the two grounding short-circuit columns (29) are arranged along the diagonal line where the intersection points of the two dipole radiation patches on the third dielectric plate (22) are located.

10. The antenna according to claim 2, characterized in that: The circular coupling patch (28) has its center located at the projection position of the intersection of the two dipole radiation patches.

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