Low-scattering dual-frequency dual-circularly polarized array antenna based on characteristic mode

Abstract

The invention discloses a low-scattering dual-frequency dual-circularly-polarized array antenna based on a characteristic mode. An antenna unit comprises a radiation unit, a lower-layer fractal metal floor, a lower-layer dielectric substrate and a feed network which are arranged in sequence, the radiation unit comprises an upper-layer high-frequency radiation patch, an upper-layer dielectric substrate, a middle-layer low-frequency radiation patch and a middle-layer dielectric substrate which are arranged in sequence; the upper-layer high-frequency radiation patch is connected to the feed network through the metal columns; the antenna unit can respectively realize left-hand circular polarization radiation and right-hand circular polarization radiation in a frequency band; in order to reduce the radar cross section (RCS), a fractal structure is introduced on the unit floor, and electromagnetic scattering is effectively suppressed on the premise that the radiation performance is not affected. After a plurality of units are arranged into an array through the one-to-four power divider, a good dual-circular polarization radiation characteristic is kept in the frequency bands of 1.545 GHz to 1.558 GHz and 2.376 GHz to 2.392 GHz, and a good low scattering characteristic is kept in the frequency band of 1 GHz to 10 GHz. The antenna is suitable for modern wireless communication and radar systems with requirements for multiple frequency bands, multiple polarizations and low detectability.

Description

Technical Field

[0001] This invention belongs to the field of antenna and electromagnetic stealth technology, and specifically relates to a low-scattering dual-frequency dual-circularly polarized array antenna based on characteristic modes. Background Technology

[0002] With the development of the times and the progress of science and technology, the array antennas carried by modern advanced electronic systems have increasingly higher requirements for low scattering, anti-interference and multi-frequency characteristics, and their stealth capability directly determines the survivability of the aircraft platform.

[0003] Traditional low-scattering single-frequency linearly polarized antennas are no longer sufficient to meet the ever-growing demands of many applications, while low-scattering multi-frequency circularly polarized antennas are attracting increasing attention due to their unique advantages. These advantages mainly include: (1) replacing multiple single-frequency antennas with multiple frequency band antennas can significantly reduce size and weight; (2) multi-frequency antennas help improve frequency band utilization efficiency and system integration; (3) circularly polarized waves experience less attenuation during transmission, which helps reduce signal fading caused by multipath effects; and (4) using circularly polarized waves can avoid signal loss caused by polarization mismatch. Based on these advantages, low-scattering circularly polarized antennas can better adapt to the diverse needs of modern advanced electronic systems, and the development of low-scattering multi-frequency circularly polarized antennas has become a current research hotspot.

[0004] Traditional circularly polarized antenna design relies heavily on engineers' experience and lacks systematic theoretical guidance. With the development of computational electromagnetics, characteristic mode theory has been widely applied to the coordinated design of antenna radiation and scattering. This theory combines the physical clarity of analytical methods with the universality of numerical methods, enabling orthogonal expansion of currents on the surface of conductors of arbitrary shapes. The characteristic electric fields excited by the corresponding characteristic currents also maintain orthogonality in the far field. Since the characteristic modes are determined only by the intrinsic physical properties of the conductor, such as geometry, material, and operating frequency, and are independent of external excitations, it can serve as the basis for analyzing the inherent electromagnetic behavior of antennas.

[0005] In terms of radiation, characteristic mode theory can identify a pair of orthogonal modes that dominate circularly polarized radiation. When these modes have similar importance and their characteristic angles differ by approximately 90°, circularly polarized waves can be efficiently excited through proper feeding, providing a clear theoretical basis for feed location and port configuration. In terms of scattering, characteristic mode theory also has significant advantages: it can reveal the contribution mechanisms of different characteristic modes to the radar cross section. By suppressing or modulating characteristic modes with high scattering contributions, the scattering value of the antenna can be reduced with almost no impact on radiation performance. Therefore, characteristic mode theory not only provides a physically intuitive optimization path for the radiation design of high-performance circularly polarized antennas but also lays the foundation for a new design method for achieving low-scattering stealth antennas, enabling unified and coordinated design of radiation and scattering performance.

[0006] Therefore, the research on low-scattering dual-frequency dual-circularly polarized array antennas with characteristic modes is of great significance in the fields of antenna and electromagnetic stealth technology. Summary of the Invention

[0007] The purpose of this invention is to provide a low-scattering dual-frequency dual-circular polarization array antenna based on characteristic modes, aiming to achieve dual-frequency, dual-circular polarization, and broadband scattering reduction design of the array antenna by utilizing characteristic mode modulation methods.

[0008] To achieve the above objectives, this invention employs eigenmode analysis to analyze a slotted metal patch structure with two layers of parasitic stubs. By controlling the size and position of the two parasitic stubs and the rectangular slot, the degenerate modes of the antenna are perturbed to form two different circular polarization modes at different frequencies. Through reasonable feeding excitation, these two pairs of orthogonal modes are simultaneously excited to achieve dual-frequency dual-circular polarization radiation. By introducing a Koch fractal structure into the metal ground plane for slotting, the scattering current path is effectively cut off, thereby achieving scattering reduction. Simultaneously, utilizing the self-similarity and multi-resonance characteristics of the fractal structure, effective scattering suppression is achieved not only in the low-frequency band but also in the high-frequency band, ultimately achieving scattering reduction within the dual-polarization broadband range.

[0009] The specific technical solution adopted in this invention is as follows: A low-scattering dual-frequency dual-circularly polarized array antenna based on characteristic modes, wherein the antenna element comprises a radiating element, a lower fractal metal ground plane, a lower dielectric substrate, and a feed network arranged sequentially; the radiating element comprises an upper high-frequency radiating patch, an upper dielectric substrate, an intermediate low-frequency radiating patch, and an intermediate dielectric substrate arranged sequentially; the upper high-frequency radiating patch is connected to the feed network through metal pillars. The upper high-frequency radiation patch adopts a metal patch structure with a first parasitic branch and a first rectangular slot, and the middle low-frequency radiation patch adopts a metal patch structure with a second parasitic branch and a second rectangular slot. The side of the upper high-frequency radiation patch with the first parasitic branch is perpendicular to the side of the middle low-frequency radiation patch with the second parasitic branch, so that the upper high-frequency radiation patch and the middle low-frequency radiation patch radiate different polarizations respectively. By controlling the dimensions of parasitic stubs and rectangular slots to perturb the degenerate modes of the antenna, two pairs of orthogonal modes with similar mode importance and characteristic angles differing by ±90° at the target frequency are adjusted to form two different circularly polarized radiation modes at different frequencies. By adjusting the characteristic angles and feeding excitation, dual-frequency dual-circularly polarized radiation is achieved.

[0010] In one embodiment, the radiating units are distributed in a 2×2 array on the lower fractal metal floor, which is a metal floor with fractal structure slotting. The power supply network is a power splitting structure of one-to-four with bent microstrip feed lines, which respectively feeds the upper high-frequency radiating patches of the four radiating units.

[0011] In one embodiment, the upper high-frequency radiating patch, the upper dielectric substrate, the middle low-frequency radiating patch, the middle dielectric substrate, the lower fractal metal ground plane, the lower dielectric substrate, and the power supply network are sequentially and tightly bonded together.

[0012] In one embodiment, when the upper high-frequency radiating patch and the middle low-frequency radiating patch are not slotted or stubbed, their top view is at the same position as the face center of the upper dielectric substrate and the middle dielectric substrate.

[0013] In one embodiment, the length direction of the first rectangular groove is parallel to the side of the upper high-frequency radiation patch on which the first parasitic branch is loaded, and the angle between the second rectangular groove and the side of the middle low-frequency radiation patch on which the second parasitic branch is loaded is 45°.

[0014] In one embodiment, the degenerate modes of the upper high-frequency radiation patch are perturbed by controlling the lengths of the first parasitic branch and the first rectangular slot, so that the upper high-frequency radiation patch forms a pair of orthogonal modes with the same mode importance and a characteristic angle difference of -90° at the target frequency of 2.4 GHz, forming a right-hand circularly polarized mode. By controlling the lengths of the second parasitic stub and the second rectangular slot, the degenerate modes of the intermediate low-frequency radiating patch are perturbed, so that the intermediate low-frequency radiating patch forms a pair of orthogonal modes with the same mode importance and a characteristic angle difference of 90° at the target frequency of 1.55 GHz, forming a left-handed circularly polarized mode.

[0015] In one embodiment, dual-frequency dual-circular polarization radiation is achieved by reasonable feeding excitation, that is, feeding excitation at the intersection of the strong mode current points of two pairs of orthogonal modes to simultaneously excite these two pairs of orthogonal modes. Since the width of the slot has little impact on the characteristic mode performance parameters of the high-frequency radiating patch and the low-frequency radiating patch in the middle layer, the impedance performance of the antenna can be adjusted by the width of the slot.

[0016] In one embodiment, the fractal metal floor is a rectangular metal floor with a grooved design incorporating a Koch fractal structure.

[0017] In one embodiment, the power supply network is a bent microstrip feed line that bypasses a slotted section of a fractal metal ground plane to maintain the continuity of the microstrip line's characteristic impedance, thereby ensuring good amplitude and phase consistency of the power divider's output signal.

[0018] In one embodiment, the intermediate low-frequency radiating patch has a circular groove with the metal pillar as the center and a radius larger than the radius of the metal pillar in the area through which the metal pillar passes. This allows the metal pillar to pass through the intermediate low-frequency patch without being electrically connected to it, thereby achieving excitation of the intermediate low-frequency patch through coupling. The metal pillar is in direct contact with the upper high-frequency radiating patch, serving as its power supply channel and ensuring the normal realization of the high-frequency circular polarization radiation function.

[0019] Compared with the prior art, the beneficial effects of the present invention are: First, because the array designed using characteristic mode theory in this invention has excellent dual-frequency dual-circular polarization radiation capability, it is suitable for modern wireless communication and radar systems that require multi-band and multi-polarization capabilities. Second, this invention utilizes a floor fractal structure to achieve broadband RCS reduction performance both inside and outside the coverage area.

[0020] Third, because this invention combines characteristic mode theory and fractal structure characteristics, the designed low-scattering dual-frequency dual-circular polarized array antenna does not require the introduction of an additional independent scattering suppression structure. It can effectively reduce the radar cross section while ensuring excellent radiation performance, thus realizing an integrated array design of radiation and scattering performance. Attached Figure Description

[0021] Figure 1 This is a structural diagram of the entire invention.

[0022] Figure 2 This is a structural diagram of the dual-frequency dual-circular polarization unit of the present invention.

[0023] Figure 3 This is a diagram of the power supply network structure of the present invention. Figure 4 This invention utilizes characteristic mode analysis to determine the mode saliency of a dual-frequency dual-circular polarization unit.

[0024] Figure 5 This is the characteristic angle of the dual-frequency dual-circular polarization unit using characteristic mode analysis in this invention.

[0025] Figure 6 These are the S-parameters and axial ratio of the array antenna of this invention.

[0026] Figure 7 This is the gain of the array antenna of this invention.

[0027] Figure 8 This is a comparison of the scattering performance of the array designed in this invention and the reference array under x-polarized plane wave incident conditions.

[0028] Figure 9 This is a comparison of the scattering performance of the array designed in this invention and the reference array under y-polarized plane wave incident conditions. Detailed Implementation

[0029] To make the objectives, features and advantages of the present invention more apparent and understandable, the invention will be further described in detail below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the invention in any way.

[0030] Reference Figure 1 , Figure 2 and Figure 3 The overall structure of the low-scattering dual-frequency dual-circularly polarized array antenna based on characteristic modes of the present invention will be described in further detail.

[0031] The antenna element of the array antenna of the present invention includes a radiating element, a lower fractal metal ground plane 5, a lower dielectric substrate 12, and a feed network 13 arranged sequentially. The radiating element is distributed in a 2×2 array on the lower fractal metal ground plane 5. The radiating element includes an upper high-frequency radiating patch 1, an upper dielectric substrate 2, an intermediate low-frequency radiating patch 3, and an intermediate dielectric substrate 4 arranged sequentially. The upper high-frequency radiating patch 1 is connected to the feed network 13 through metal pillars 6.

[0032] In this embodiment, the upper dielectric substrate 2, the middle dielectric substrate 4, and the lower dielectric substrate 12 are made of the same material but have different thicknesses. Their top view outlines are identical and square, with a length and width of 80 mm each. They all use FR-4 dielectric material with a dielectric constant of 4.3 and a loss tangent of 0.025. Their heights are H1=2.4 mm, H2=2.8 mm, and H3=1 mm, respectively. The upper high-frequency radiating patch 1, the upper dielectric substrate 2, the middle low-frequency radiating patch 3, the middle dielectric substrate 4, the lower fractal metal ground plane 5, the lower dielectric substrate 12, and the feed network 13 are sequentially and tightly bonded together. When no slotting or branching is applied, the top view centers of the upper high-frequency radiating patch 1 and the middle low-frequency radiating patch 3 are located at the same position as the face centers of the upper dielectric substrate 2 and the middle dielectric substrate 4.

[0033] like Figure 2 As shown, the upper high-frequency radiation patch 1 of this invention adopts a metal patch structure with a first parasitic branch 7 and a first rectangular groove 8. Without the first parasitic branch 7, its length and width are equal (L1=28mm). The first parasitic branch 7 is L-shaped, with lengths of L4=1.5mm and L5=4.5mm, and a width of W2=mm. The first rectangular groove 8 has a length of L3=mm, a width of W1=mm, and is located at a distance of L2=mm from the center of the lower edge of the metal patch structure.

[0034] Similarly, the intermediate layer low-frequency radiation patch 3 adopts a metal patch structure with a second parasitic branch 9 and a second rectangular slot 10. Excluding the second parasitic branch 9, its length and width are L6=28mm and L7=28mm, respectively. The loaded second parasitic branch 9 is L-shaped, with lengths of L8=3.2mm and L9=8.4mm and a width of W3=1.2mm. The loaded second rectangular slot 10 is centered at the midpoint of the diagonal of the rectangular patch, with a length of L3=12mm and a width of W1=0.4mm. A circular slot 11 is also loaded on the intermediate layer low-frequency radiation patch 3. The center of this circular slot 11 is L11=15mm from the left edge and L12=14.86mm from the bottom edge of the patch, and its diameter is D1=1.6mm. The metal column 6, with the center of the circular groove 11 as its center and a diameter D2=0.4mm, is connected from the upper high-frequency radiation patch 1 to the feed network 13, and is not electrically connected to the middle low-frequency patch 3. Thus, the middle low-frequency patch 3 is excited through coupling, and it serves as the feed channel for the upper high-frequency radiation patch 1, ensuring the normal realization of the high-frequency circular polarization radiation function.

[0035] In this invention, the side of the upper high-frequency radiation patch 1 on which the first parasitic branch 7 is loaded is perpendicular to the side of the middle low-frequency radiation patch 3 on which the second parasitic branch 9 is loaded, so that the upper high-frequency radiation patch 1 and the middle low-frequency radiation patch 3 radiate with different polarizations. For example, the length direction of the first rectangular groove 8 is parallel to the side of the upper high-frequency radiation patch 1 on which the first parasitic branch 7 is loaded, and the angle between the second rectangular groove 10 and the side of the middle low-frequency radiation patch 3 on which the second parasitic branch 9 is loaded is 45°.

[0036] like Figure 2 As shown, the lower fractal metal floor 5 of this invention has a symmetrical structure. Specifically, it is a metal floor with fractal slotting, for example, a rectangular metal floor with slotting treatment using Koch fractal structure introduced on the basis of a traditional rectangular metal floor. This structure is based on the fractal construction of the Koch curve. By repeatedly dividing the line segment into three equal parts and replacing the middle segment with the two sides of an equilateral triangle, a self-similar sawtooth boundary is formed. Its structural dimensions are L13=16mm, L14=14mm, L15=7mm, and L16=5.33mm. This design utilizes the self-similarity and multi-scale resonance characteristics of fractal geometry to effectively disrupt the scattering current distribution on the floor surface, thereby reducing the radar cross-section within the antenna operating frequency band. At the same time, the resonant response excited by the fractal structure in multiple frequency bands can maintain good scattering suppression capability in a wide frequency range outside the operating frequency band, ultimately achieving a dual-polarization broadband scattering reduction effect.

[0037] like Figure 3As shown, the power distribution network 13 of the present invention adopts a bent microstrip feed line for a one-to-four power distribution design, which feeds the upper high-frequency radiating patch 1 of the four radiating elements respectively. The design principle is to bypass the slotted part of the lower fractal metal ground plane 5 to avoid the characteristic impedance change caused by the discontinuity of the ground plane, thereby maintaining the impedance continuity of the microstrip feed line and the signal transmission stability. The power supply energy is transferred from the bent microstrip feed line to the antenna element through the metal pillar electrical connection, so as to achieve good amplitude and phase consistency of the output signal of the power divider.

[0038] Based on the above structure, the present invention can perturb the degenerate modes of the antenna by controlling the size of the parasitic stubs and rectangular slots, adjust two pairs of orthogonal modes with similar mode importance and characteristic angles differing by ±90° at the target frequency, form two different circularly polarized radiation modes at different frequencies, and achieve dual-frequency dual-circularly polarized radiation by adjusting the characteristic angles and power feeding excitation.

[0039] Specifically, by controlling the lengths of the first parasitic stub 7 and the first rectangular slot 8, the degenerate modes of the upper high-frequency radiating patch 1 are perturbed, causing the upper high-frequency radiating patch 1 to form a pair of orthogonal modes with equal mode importance and characteristic angles differing by -90° at the target frequency of 2.4 GHz, thus forming a right-hand circularly polarized mode. Similarly, by controlling the lengths of the second parasitic stub 9 and the second rectangular slot 10, the degenerate modes of the middle low-frequency radiating patch 3 are perturbed, causing the middle low-frequency radiating patch 3 to form a pair of orthogonal modes with equal mode importance and characteristic angles differing by 90° at the target frequency of 1.55 GHz, thus forming a left-hand circularly polarized mode.

[0040] like Figure 4 and Figure 5 As shown, characteristic mode analysis was performed on the open rectangular slot metal patch with parasitic branches loaded in two layers. It can be seen that two pairs of orthogonal modes with similar mode importance and characteristic angles differing by ±90° appeared at 1.55GHz and 2.4GHz, forming two modes with different circular polarizations. By reasonably exciting the distribution of mode currents, these two circular polarization modes can be well excited.

[0041] like Figure 6 As shown, the present invention provides a low-scattering dual-frequency dual-circular polarization array antenna based on characteristic modes, which operates in the 1.546–1.555 GHz and 2.395–2.413 GHz frequency bands and can realize left-hand circular polarization and right-hand circular polarization radiation, respectively.

[0042] like Figure 7 As shown, the low-scattering dual-frequency dual-circularly polarized array antenna based on characteristic modes of the present invention exhibits good radiation performance at frequencies of 1.55 GHz and 2.4 GHz. like Figure 8As shown, the present invention provides a low-scattering dual-frequency dual-circular polarization array antenna based on characteristic modes, which has a reduction effect in both polarizations. Compared with the reference antenna, its maximum single-station RCS reduction value is 10dB in both x-polarization and y-polarization, and it has a reduction effect in the 1-10GHz frequency band.

[0043] The simulation results above demonstrate that, compared to existing technologies, this invention not only possesses excellent dual-frequency, dual-circular polarization radiation capabilities, making it highly suitable for the multi-band, multi-polarization requirements of modern wireless communication and radar systems, but also achieves wide-bandwidth radar cross-section (RCS) reduction performance through a floor fractal structure, covering both in-band and out-of-band frequency ranges. Combining characteristic mode theory and the characteristics of fractal structures, this design maintains superior radiation performance while effectively reducing the radar cross-section without the need for an additional independent scattering suppression structure, thus successfully achieving an integrated array design that combines radiation and scattering performance. This low-scattering dual-frequency, dual-circular polarization array antenna provides an efficient and integrated solution for high-performance wireless communication and radar systems.

Claims

1. A low-scattering dual-frequency dual-circularly polarized array antenna based on characteristic modes, characterized in that, Its antenna unit includes a radiating element, a lower fractal metal ground plane (5), a lower dielectric substrate (12), and a feed network (13) arranged in sequence; the radiating element includes an upper high-frequency radiating patch (1), an upper dielectric substrate (2), an intermediate low-frequency radiating patch (3), and an intermediate dielectric substrate (4) arranged in sequence; the upper high-frequency radiating patch (1) is connected to the feed network (13) through a metal pillar (6); The upper high-frequency radiation patch (1) adopts a metal patch structure with a first parasitic branch (7) and a first rectangular groove (8), and the middle low-frequency radiation patch (3) adopts a metal patch structure with a second parasitic branch (9) and a second rectangular groove (10); the side of the upper high-frequency radiation patch (1) with the first parasitic branch (7) is perpendicular to the side of the middle low-frequency radiation patch (3) with the second parasitic branch (9), so that the upper high-frequency radiation patch (1) and the middle low-frequency radiation patch (3) radiate different polarizations respectively; By controlling the dimensions of the parasitic stubs (7,9) and the rectangular slots (8,10), the degenerate modes of the antenna are perturbed, and two pairs of orthogonal modes with similar mode importance and characteristic angles differing by ±90° at the target frequency are adjusted to form two different circularly polarized radiation modes at different frequencies. By adjusting the characteristic angles and power feeding excitation, dual-frequency dual-circularly polarized radiation is achieved.

2. The low-scattering dual-frequency dual-circular polarization array antenna based on characteristic modes according to claim 1, characterized in that, The radiating units are arranged in a 2×2 array on the lower fractal metal floor (5). The lower fractal metal floor (5) is a metal floor with a fractal structure and slots. The power supply network (13) is a bent microstrip feed line with a one-to-four power splitting structure, which feeds the upper high-frequency radiating patches (1) of the four radiating units respectively.

3. The low-scattering dual-frequency dual-circularly polarized array antenna based on characteristic modes according to claim 1, characterized in that, The upper high-frequency radiation patch (1), the upper dielectric substrate (2), the middle low-frequency radiation patch (3), the middle dielectric substrate (4), the lower fractal metal floor (5), the lower dielectric substrate (12), and the power supply network (13) are sequentially and tightly bonded together.

4. The low-scattering dual-frequency dual-circularly polarized array antenna based on characteristic modes according to claim 1, characterized in that, When the upper high-frequency radiation patch (1) and the middle low-frequency radiation patch (3) are not slotted or stubbed, their top view is at the same position as the face center of the upper dielectric substrate (2) and the middle dielectric substrate (4).

5. A low-scattering dual-frequency dual-circularly polarized array antenna based on characteristic modes according to claim 1, characterized in that, The length direction of the first rectangular groove (8) is parallel to the side of the upper high-frequency radiation patch (1) on which the first parasitic branch (7) is loaded, and the angle between the second rectangular groove (10) and the side of the middle low-frequency radiation patch (3) on which the second parasitic branch (9) is loaded is 45°.

6. The low-scattering dual-frequency dual-circular polarization array antenna based on characteristic modes according to claim 1, characterized in that, By controlling the lengths of the first parasitic stub (7) and the first rectangular slot (8), the degenerate mode of the upper high-frequency radiation patch (1) is perturbed, so that the upper high-frequency radiation patch (1) forms a pair of orthogonal modes with the same mode importance and a characteristic angle difference of -90° at the target frequency of 2.4 GHz, forming a right-hand circular polarization mode. By controlling the lengths of the second parasitic stub (9) and the second rectangular slot (10), the degenerate modes of the intermediate low-frequency radiation patch (3) are perturbed, so that the intermediate low-frequency radiation patch (3) forms a pair of orthogonal modes with the same mode importance and a difference of 90° in characteristic angles at the target frequency of 1.55 GHz, thus forming a left-handed circularly polarized mode.

7. A low-scattering dual-frequency dual-circularly polarized array antenna based on characteristic modes according to claim 1 or 6, characterized in that, Dual-frequency dual-circular polarization radiation is achieved by simultaneously exciting the two pairs of orthogonal modes through feeding at the intersection of the strong mode current points of the two pairs of orthogonal modes, and the impedance performance of the antenna is adjusted by the slot width.

8. A low-scattering dual-frequency dual-circularly polarized array antenna based on characteristic modes according to claim 1, characterized in that, The fractal metal floor (5) is a rectangular metal floor with a grooved design incorporating a Koch fractal structure.

9. A low-scattering dual-frequency dual-circular polarization array antenna based on characteristic modes according to claim 1, characterized in that, The power supply network (13) is a bent microstrip feed line that bypasses the fractal metal floor (5) and is slotted to maintain the continuity of the characteristic impedance of the microstrip line so that the output signal of the power divider has good amplitude and phase consistency.

10. A low-scattering dual-frequency dual-circularly polarized array antenna based on characteristic modes according to claim 1, characterized in that, The intermediate low-frequency radiation patch (3) has a circular groove (11) with the metal column (6) as the center and a radius larger than the radius of the metal column in the area through which the metal column (6) passes. This allows the metal column (6) to pass through the intermediate low-frequency patch (3) without being electrically connected to it, thereby achieving excitation of the intermediate low-frequency patch (3) through coupling. The metal column (6) is in direct contact with the upper high-frequency radiation patch (1) as its power supply channel, ensuring the normal realization of the high-frequency circular polarization radiation function.

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