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

Abstract

This invention proposes an ultra-wideband, low-profile, wide-scanning-angle dual-polarized phased array antenna, comprising a metasurface cladding, a radiating layer, and a metal ground plane stacked sequentially from top to bottom. The metasurface cladding includes a first dielectric substrate and multiple periodically arranged open-ring resonant elements printed on its surface. Each open-ring resonant element has four uniformly distributed openings on its ring. In this invention, the ring of the open-ring resonant element on the metasurface cladding is divided into four parts by the four uniformly distributed openings, thus no longer maintaining a complete ring structure. When electromagnetic waves act on the antenna, this ring prevents the induced current from forming a continuous ring-shaped induced current, ensuring that the current on the ring maintains the same direction as the antenna array, effectively widening the beam scanning angle. This invention uses a feeding structure composed of a grounded metal via and a coaxial connector for direct feeding, avoiding the increase in antenna profile height caused by using a balun.

Description

Technical Field

[0001] This invention belongs to the field of antenna technology and relates to a dual-polarized phased array antenna, specifically an ultra-wideband, low-profile, wide-scanning-angle dual-polarized phased array antenna that can be applied to radar systems. Background Technology

[0002] A phased array antenna is an antenna that changes its radiation pattern shape by controlling the feed phase of the radiating elements in the array. Controlling the phase changes the direction of the antenna's maximum radiation value, achieving beam scanning. Antenna polarization is classified into linear polarization, circular polarization, and elliptical polarization. A dual-polarized antenna is one where both horizontal and vertical linear polarization exist within a single radiating element. Dual-polarized phased array antennas further enhance antenna performance, achieving good results in different polarization directions. This rapid beam scanning capability can be applied to both horizontal and vertical polarized beams simultaneously, improving system response speed and target search capability.

[0003] Phased array antennas require broadband characteristics. Traditional phased array antennas use broadband array elements to achieve broadband performance, but the spacing between array elements causes grating lobes, limiting the bandwidth of traditional phased array antennas. Tightly coupled array antennas, on the other hand, utilize the strong coupling effect between antenna elements to avoid grating lobes, extending the antenna bandwidth and achieving ultra-wideband matching. Therefore, phased arrays based on tight coupling can achieve broadband characteristics. Furthermore, to adapt to diverse application scenarios, miniaturized phased array antennas make these devices more portable, flexible, and easier to deploy and operate. The design of phased array antennas is also gradually developing towards lightweighting and miniaturization.

[0004] Patent application CN11387186A, entitled "A Low-Profile Wide-Width-Angle Two-Dimensional Scanning Dual-Polarized Phased Array Antenna and Its Application," discloses a low-profile wide-bandwidth two-dimensional scanning dual-polarized phased array antenna, comprising a polarized dipole planar array, a metal substrate, and a planar printed metasurface. The dual-polarized dipole planar array is placed between the metal substrate and the planar printed metasurface; the metal substrate and the planar printed metasurface are parallel. This invention, based on the tight coupling effect, utilizes rather than suppresses the coupling between elements to achieve ultra-wideband characteristics not possessed by traditional phased array antennas, and can effectively suppress the grating lobe problem of traditional phased array antennas. Based on the tight-coupled array antenna, an integrated Marchand balun and a planar printed metasurface are introduced, further expanding the bandwidth and scanning angle range of the phased array antenna, and reducing the antenna's profile height. Because this invention uses a square ring metasurface structure, when electromagnetic waves act on the antenna, the induced current is a continuous ring-shaped induced current on it, instead of being consistent with the antenna current in the desired direction. This results in the antenna's scanning angle range in the E plane being only 0 to 45°, which affects the further widening of the beam scanning angle. In addition, this invention uses balun feeding, which results in a high antenna profile. Summary of the Invention

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

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

[0007] The antenna described above, specifically the radiating layer 2, includes a second dielectric substrate 21 stacked vertically and a composite dielectric substrate layer composed of a third dielectric substrate 22, a fourth dielectric substrate 23, a fifth dielectric substrate 24, and a sixth dielectric substrate 25, as well as two sets of feed structures 26. The upper surface of the third dielectric substrate 22 is printed with two intersecting dipole radiating patches 27. Each dipole radiating patch 27 includes a grounded dipole radiating patch 271 and a feed dipole radiating patch 272. The upper surface of the fourth dielectric substrate 23 is located between the two dipole radiating patches. A circular coupling patch 28 is printed on the projection position of the plate, and the circular coupling patch 28 is connected to the metal ground plate 3 through two grounding short-circuit posts 29; two pairs of rectangular metal patches 30 are printed on the upper surface of the fifth dielectric plate 24 and the sixth dielectric plate 25; the power supply structure 26 includes a grounding metal through hole 261 for connecting the grounding dipole radiating patch 271, a pair of rectangular metal patches and the metal ground plate 3, and a coaxial connector 262 for connecting the inner conductor to the power supply dipole radiating patch 272 and another pair of rectangular metal patches.

[0008] The antenna described above, the second dielectric substrate 21 and the composite dielectric substrate layer, have the same dimensions as the first dielectric substrate 11 and the metal ground plane 3. The second dielectric substrate 21 is made of a dielectric material with a relative permittivity of 1, and the metal ground plane 3 is provided with a through hole for the coaxial connector 262 to pass through.

[0009] In the aforementioned antenna, the intersection of the two dipole radiating patches 27 printed on the upper surface of the third dielectric substrate 22 is located on a diagonal line of the third dielectric substrate 22 and is offset to the lower right of the center position of the third dielectric substrate 22.

[0010] The aforementioned antenna, wherein the composite dielectric substrate layer has a cylindrical cavity extending vertically through the third dielectric substrate 22, the fourth dielectric substrate 23, the fifth dielectric substrate 24, and the sixth dielectric substrate 25, and the central axis of the cylindrical cavity is located on the diagonal line of the intersection point of the two dipole radiating patches on the third dielectric substrate 22.

[0011] The cylindrical cavity of the aforementioned antenna has its central axis located to the upper left of the diagonal line where the intersection of the two dipole radiating patches is located, which is offset from the center of the third dielectric plate 22.

[0012] The antenna described above has two dipole radiating patches 27 printed on its upper surface, which are perpendicularly intersecting.

[0013] The aforementioned antenna, specifically the feed dipole radiating patch 272, comprises two composite structures. Each composite structure includes an isosceles trapezoidal metal patch and an isosceles triangular metal patch whose base is joined to the lower base of the isosceles trapezoidal metal patch. The vertices of the isosceles triangular metal patches in the two composite structures are arranged opposite each other. The connection point between the feed dipole radiating patch 272 and the coaxial connector 262 is located at the upper base of one of the isosceles trapezoidal metal patches.

[0014] The two grounding short-circuit posts 29 of the aforementioned antenna are arranged along the diagonal of the intersection of the two dipole radiating patches on the third dielectric substrate 22.

[0015] The circular coupling patch 28 of the aforementioned antenna has its center located at the projection position of the intersection of the two dipole radiating patches.

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

[0017] 1. In this invention, the ring of the open resonant ring unit on the metasurface coating is divided into four parts by four uniformly distributed openings, thus no longer maintaining a complete ring structure. The four openings increase the symmetry of the ring structure, enabling more stable electromagnetic coupling with the antenna at different scanning angles and frequencies, which helps with impedance matching between the antenna and free space. When electromagnetic waves act on the antenna, the ring prevents the induced current from forming a continuous ring-shaped induced current, ensuring that the current on the ring remains in the same direction as the antenna array. Compared with the prior art, this invention effectively widens the beam scanning angle.

[0018] 2. This invention uses a feeding structure consisting of a grounded metal through-hole and a coaxial connector for direct feeding, avoiding the increase in antenna profile height caused by using a balun. Attached Figure Description

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

[0020] Figure 2 This is a schematic diagram of the structure of the metasurface coating of the present invention.

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

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

[0023] Figure 5 This is a simulation diagram of the standing wave ratio (SWR) during E-plane and H-plane scanning in the 2-20 GHz frequency band of this invention. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0025] Reference Figure 1 The present invention comprises a metasurface coating 1, a radiation layer 2 and a metal floor 3 stacked sequentially from top to bottom;

[0026] Reference Figure 2 The metasurface coating 1 includes a first dielectric substrate 11 and multiple open-ring resonant units 12 periodically arranged on its upper surface; each open-ring resonant unit 12 has four uniformly distributed openings on its ring. At different scanning angles, such as 60° scanning in the E-plane and 45° scanning in the H-plane, the current path is cut off because the open-ring resonant unit structure is split into four parts, preventing the formation of a ring current and ensuring that the current maintains the same direction as the antenna array. This indicates that the structure has good coupling characteristics with the antenna. This good coupling helps with impedance matching between the antenna and free space, enabling the antenna to maintain good performance during wide-angle scanning, thus achieving wide-angle beam scanning. Furthermore, the four openings give the entire ring structure higher symmetry. This symmetry not only benefits the performance stability of the antenna at different scanning angles but also provides potential conditions for designing a dual-polarization structure. The highly symmetrical structure makes it easier to control and optimize the antenna's radiation characteristics in different polarization directions, thereby achieving dual-polarization functionality. When a dielectric cladding layer is applied above a tightly coupled dipole unit, the cladding layer can alter the electromagnetic field distribution around the antenna, counteracting the reactance changes caused by the metal ground plane, thereby further broadening the bandwidth and extending the antenna scanning angle. However, the ideal dielectric cladding layer thickness is one-quarter of the dielectric wavelength corresponding to the center frequency, which results in a relatively high overall antenna profile. Using equivalent medium theory, equivalent parameters of the metasurface cladding layer, which is equivalent to the dielectric cladding layer, can be extracted. The metasurface cladding layer described in this invention has a thickness of 1.5 mm, replacing the 2.5 mm thick F4BM22 dielectric substrate with a relative permittivity of 2.2, thus reducing the overall antenna profile.

[0027] Reference Figure 3 The radiating layer 2 includes a second dielectric plate 21 stacked on top of each other, 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 sets of feeding structures 26. The second dielectric plate 21 is a dielectric plate with a thickness of 1 mm and a relative permittivity of 1. The composite dielectric plate layer is an F4BM22 dielectric plate with a relative permittivity ε = 2.2 and a loss tangent tanδ = 0.0015 of different thicknesses. The dimensions of the second dielectric plate 21 and the composite dielectric plate layer are the same as those of the first dielectric plate 11 and the metal ground plate 3.

[0028] The upper surface of the third dielectric substrate 22 is printed with two intersecting dipole radiating patches 27, which are perpendicularly intersected to achieve dual polarization. The dipole radiating patches 27 include a grounding dipole radiating patch 271 and a feeding dipole radiating patch 272. The upper surface of the fourth dielectric substrate 23 is printed with a circular coupling patch 28 at the projection position of the two dipole radiating patches. The circular coupling patch 28 is connected to the metal ground plane 3 through two grounding short-circuit posts 29. Its center is located at the projection position of the intersection of the two dipole radiating patches, and the two dipole radiating 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, which moves the antenna resonant point out of the band; the upper surfaces of the fifth dielectric substrate 24 and the sixth dielectric substrate 25 are each printed with two pairs of rectangular metal patches 30, which are used 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 radiating patch 271, a pair of rectangular metal patches, and a metal ground plane 3, and a coaxial connector 262 connecting the inner conductor to the feeding dipole radiating patch 272 and another pair of rectangular metal patches. To achieve the conversion from unbalanced to balanced feeding, a balun is generally used, but this increases the overall antenna profile. Therefore, this invention uses coaxial feeding and adds two grounding short-circuit posts 29 to move the common-mode resonance caused by unbalanced feeding out of band.

[0031] The composite dielectric substrate layer has a cylindrical cavity extending vertically through the third dielectric substrate 22, the fourth dielectric substrate 23, the fifth dielectric substrate 24, and the sixth dielectric substrate 25. The central axis of this cylindrical cavity is located on the diagonal line of the intersection point of the two dipole radiating patches on the third dielectric substrate 22. This cylindrical cavity aims to reduce the effective dielectric constant of the dielectric substrate, and its radius is determined by the following formula:

[0032]

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

[0034] Reference Figure 4Each dipole radiating patch includes an isosceles trapezoidal metal patch and an isosceles triangular metal patch whose base is spliced ​​with the lower base of the isosceles trapezoidal metal patch. The power-feeding dipole radiating patch 271 and the grounding dipole radiating patch 272 are respectively connected to the upper base of the isosceles trapezoidal metal patch via the inner conductor of the coaxial connector 262 and the grounding metal through hole 261.

[0035] The working principle of this invention is as follows: the antenna feeds the dipole radiating patch 27 of the third dielectric substrate 22 through two sets of feeding structures 26, causing the dipole radiating patch 27 to radiate outwards; to improve the impedance matching of the array without excessively increasing the array profile and weight, a metasurface coating 1 is used to replace the dielectric coating; a circular coupling patch 28 and two grounding short-circuit posts 28 form a ridge waveguide structure, which can move the common-mode resonant point caused by unbalanced feeding outside the antenna's operating frequency. Two pairs of rectangular patches are connected between the grounding metal via 261 and the coaxial connector 262 to increase coupling, improve antenna matching, and increase bandwidth.

[0036] The technical effects of the present invention will be further explained below with reference to simulation results:

[0037] 1. Experimental conditions and contents:

[0038] The relationship between VSWR and frequency during E-plane scanning in the 2–20 GHz frequency band of this invention was simulated using ANSYS Electronics Desktop v.18.2. The results are as follows: Figure 5 As shown.

[0039] 2. Analysis of experimental results:

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

Claims

1. A dual-polarized phased array antenna with ultra-wideband, low profile, and wide scanning angle, comprising a metasurface cladding (1), a radiating layer (2), and a metal ground plane (3) stacked sequentially from top to bottom; the metasurface cladding (1) comprises a first dielectric substrate (11) and a plurality of open resonant ring units (12) periodically arranged on its upper surface; characterized in that, The open resonant ring unit (12) has four evenly distributed openings on its ring. The radiation layer (2) includes a second dielectric plate (21) stacked on top of each other 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), as well as two sets of feeding structures (26); the upper surface of the third dielectric plate (22) is printed with two intersecting dipole radiation patches (27); the dipole radiation patches (27) include a grounded dipole radiation patch (271) and a fed 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. The circular coupling patch (28) is connected to the metal ground plane (3) through 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 power supply structure (26) includes a grounding metal through hole (261) for connecting the grounding dipole radiating patch (271), a pair of rectangular metal patches and the metal ground plane (3), and a coaxial connector (262) for connecting the inner conductor to the power supply dipole radiating patch (272) and another pair of rectangular metal patches.

2. The antenna according to claim 1, characterized in that, The second dielectric plate (21) and the composite dielectric plate layer have the same plate size as the first dielectric plate (11) and the metal floor (3). The second dielectric plate (21) is made of a dielectric material with a relative permittivity of 1, and the metal floor (3) is provided with through holes for the coaxial connector (262) to pass through.

3. The antenna according to claim 1, characterized in that, The intersection 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 is offset to the lower right of the center position of the third dielectric plate (22).

4. The antenna according to claim 3, characterized in that, The composite dielectric plate layer has a cylindrical cavity that runs vertically through the third dielectric plate (22), the fourth dielectric plate (23), the fifth dielectric plate (24), and the sixth dielectric plate (25). 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.

5. The antenna according to claim 4, characterized in that, The cylindrical cavity has its central axis located to the upper left of the diagonal line where the intersection of the two dipole radiating patches is located, which is offset from the center of the third dielectric plate (22).

6. The antenna according to claim 1, characterized in that, The third dielectric plate (22) has two dipole radiation patches (27) printed on its upper surface that are perpendicularly intersecting.

7. The antenna according to claim 1, characterized in that, The feed dipole radiating patch (272) includes two composite structures. Each composite structure includes an isosceles trapezoidal metal patch and an isosceles triangular metal patch whose base is spliced ​​with the lower base of the isosceles trapezoidal metal patch. The vertices of the isosceles triangular metal patches in the two composite structures are arranged opposite each other. The connection point between the feed dipole radiating patch (272) and the coaxial connector (262) is located at the upper base of one of the isosceles trapezoidal metal patches.

8. The antenna according to claim 1, characterized in that, The center lines of the two grounding short-circuit posts (29) are arranged along the diagonal of the intersection of the two dipole radiating patches on the third dielectric plate (22).

9. The antenna according to claim 1, 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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