Broadband circularly polarized antenna with adjustable feed position

Abstract

The utility model discloses a broadband circularly polarized antenna with an adjustable feed position, which mainly solves the problems that the feed position of the existing antenna cannot be adjusted according to the requirements of radar equipment and the broadband cannot be considered. The antenna comprises an antenna housing (1), an upper radiator (2), a lower radiator (3) and an antenna pedestal (4). The antenna housing (1) is made of a wave-transparent material; the upper radiator (2) comprises an upper-layer medium and an upper-layer patch from top to bottom; the radiator (3) comprises five layers from top to bottom, the first layer comprises a lower-layer patch and a metal ring, the second layer comprises a middle-layer medium, a metal ring column and a short circuit pin, the third layer comprises a feeder line, the fourth layer comprises a lower-layer medium and a through hole, and the fifth layer comprises a grounding plate; the antenna seat (4) is a metal seat with an air cavity structure and is provided with three fixing surfaces which are respectively used for fixing the antenna housing, the upper radiator and the lower radiator. The antenna can adjust the feed position according to the requirements of radar equipment, has the characteristic of broadening the frequency band, and can be used for satellite communication and remote control and telemetering.

Description

Technical Field

[0001] This utility model belongs to the field of radar equipment technology, specifically relating to a broadband circularly polarized antenna that can be used for satellite communication, remote control and telemetry. Background Technology

[0002] With the continuous development of satellite communication, remote control and telemetry technologies, circularly polarized antennas have become the preferred antenna form for satellite communication, remote control and telemetry technologies because they can be used to receive arbitrary linearly polarized waves and can also be received by arbitrary linearly polarized antennas.

[0003] Microstrip antennas are widely used in the field of circularly polarized antennas due to their advantages such as small size, thin profile, light weight, and low cost. The principle of microstrip antennas in generating circularly polarized waves is to generate two mutually perpendicular linearly polarized electric field components, with equal amplitude and a 90° phase difference between them.

[0004] ISBN 978-7-118-10931-3, "Circularly Polarized Antenna Technology," discloses a broadband stacked square-chamfered circularly polarized patch antenna. It consists of two layers of square-chamfered patches of different sizes printed on a dielectric substrate, an air gap, and a ground plane. The bottom patch is fed by a probe, and the upper patch receives excitation through coupling with the bottom patch. Because this antenna uses an offset feed method and has a fixed feed position, the feed position cannot be adjusted arbitrarily according to equipment requirements, thus failing to meet the needs of the equipment's back-end structure.

[0005] Article number 1003-3106(2021)04-0308-05 discloses a center-fed circularly polarized antenna design, in which the antenna radiating element adopts a microstrip patch form, and the feed point is located at the center of the radiating patch. This antenna has a simple structure and is center-fed, but because its bandwidth is only 8.9% (VSWR≤1.5), it cannot meet practical requirements when a wider operating bandwidth is required. Utility Model Content

[0006] The purpose of this invention is to address the shortcomings of the prior art by proposing a broadband circularly polarized antenna with adjustable feed position, which allows the antenna feed position to be adjusted according to equipment requirements while meeting the operating bandwidth, thereby satisfying the back-end structure requirements of the equipment.

[0007] The technical solution of this utility model is implemented as follows:

[0008] A broadband circularly polarized antenna with adjustable feed position includes an antenna radome 1, an upper radiator 2, a lower radiator 3, and an antenna mount 4, characterized in that:

[0009] The lower radiator 3 comprises five layers from top to bottom. The first layer includes a lower patch 31 and a metal ring 32; the second layer includes a middle dielectric 33, a metal ring post 34, and a shorting pin 35; the third layer includes a feed line 36; the fourth layer includes a lower dielectric 37 and a through-hole 38; and the fifth layer includes a ground plane 39. One end of the feed line 36 is connected to the metal ring 32 through the metal ring post 34, and the other end is connected to the lower patch 31 through the shorting pin 35.

[0010] Both the upper radiator 2 and the lower radiator 3 are fixed to the antenna mount 4, and the upper and lower radiators are provided with multiple adjustment parameters, which together with the parameters of the antenna mount 4 adjust the circular polarization characteristics of the antenna.

[0011] Preferably, the lower patch 31 is a square patch with a side length of a3. One set of opposite corners of the square patch is chamfered, and the chamfered corners are in the shape of isosceles right triangles, which is used to realize the circular polarization of the antenna; the other set of opposite corners is rounded, which is used to complete the miniaturization of the antenna; the square patch has a circular through hole, and a set of opposite sides are connected to a rectangular microstrip line, which is used to adjust the antenna impedance matching.

[0012] Preferably, the outer diameter of the metal ring 32 is 1.8 to 2.2 times the inner diameter;

[0013] Preferably, the inner diameter of the metal ring post 34 is the same as the diameter of the through hole 38;

[0014] Preferably, the feed line 36 is a rectangular structure, and its length L2 is not less than the distance between the metal ring post 34 and the shorting pin 35; the width W2 of the feed line is given an initial value by the microstrip line characteristic impedance formula, and the final value is determined by simulation optimization.

[0015] Preferably, the upper radiator 2 comprises an upper dielectric 21 and an upper patch 22 from top to bottom; the upper patch 22 is a square patch with a side length of a1, which is greater than the side length of the lower patch 31, a3; one set of its diagonal chamfers is an isosceles right triangle, and the direction of the chamfers is consistent with the direction of the chamfers of the lower patch 31; the diagonal direction of the other set of rounded corners is consistent with the direction of the rounded corners of the lower patch 31.

[0016] Compared with the prior art, this utility model has the following advantages:

[0017] 1. The lower radiator of this utility model adopts a multi-layer structure and introduces a feed line structure, a metal ring column and a short-circuit pin, which makes the antenna feeding position more flexible, that is, the feeding position can be either offset feeding or center feeding.

[0018] 2. Because this utility model has multiple adjustment parameters, the low-frequency characteristics can be adjusted by the parameters of the upper radiator, and the high-frequency and intermediate-frequency characteristics can be adjusted by the parameters of the lower radiator, so that the antenna can meet the performance requirements with a wider operating bandwidth.

[0019] 3. This utility model, by opening a circular hole in the lower patch of the lower radiator and introducing a metal ring, makes the antenna rear connector easy to weld, the process simple, and the antenna highly practical. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0021] Figure 2 This is an exploded view of the structure of this utility model;

[0022] Figure 3 This is a schematic diagram of the radome in this utility model;

[0023] Figure 4 This is a schematic diagram of the upper radiator in this utility model;

[0024] Figure 5 This is a schematic diagram of the lower radiator in this utility model;

[0025] Figure 6 This is a schematic diagram of the antenna mount in this utility model;

[0026] Figure 7 A schematic diagram of an existing offset-fed radiator;

[0027] Figure 8 This is a simulation result diagram of the standing wave coefficient of an embodiment of this utility model;

[0028] Figure 9 The simulation results of the standing wave coefficient after replacing the lower radiator of this embodiment with an existing lower radiator are shown in the figure. Detailed Implementation

[0029] The embodiments and effects of this utility model are described in detail below with reference to the accompanying drawings.

[0030] Reference Figure 1 and Figure 2 The antenna in this embodiment includes: an antenna cover 1, an upper radiator 2, a lower radiator 3, and an antenna mount 4. The antenna cover 1 is located on the outermost layer, and the antenna mount 4 is located on the bottom layer. The two are connected to form a closed space. The upper radiator 2 and the lower radiator 3 are both located inside the closed space, and the upper radiator 2 is located directly above the lower radiator 3.

[0031] refer to Figure 3The radome 1 consists of two parts: the upper part has a curved structure for wave transmission; the lower part has a ring-column structure for mounting and fixing the radome to the antenna mount. The radome is made of a wave-transmitting material whose material meets the requirements of installation curvature and environmental adaptability, i.e., meeting the requirements of wind, rain, sand, and dust. Its thickness h is an initial value calculated according to the optimal wave transmission formula of the material, under the premise of meeting structural strength requirements. The calculation formula is as follows:

[0032]

[0033] In the formula, λ0 represents the wavelength of the antenna's operating center frequency, and ε r The dielectric constant of the material is represented by m, which represents any positive integer; the final value of h is determined through simulation optimization.

[0034] The inner diameter φ1 of the radome is the same as the outer diameter φ5 of the antenna mount 4.

[0035] In this embodiment, the radome material is, but is not limited to, polytetrafluoroethylene with a dielectric constant of 2.08 and a loss tangent of 0.021, and the upper part is, but is not limited to, a hemispherical curved structure with an inner diameter φ1 of 98mm.

[0036] refer to Figure 4 The upper radiator 2 comprises an upper dielectric 21 and an upper patch 22, with the upper dielectric 21 located directly above the upper patch 22. The upper dielectric 21 is a microwave laminate with a thickness of h1. Figure 4 As shown in (a).

[0037] The upper patch 22 is a square patch with a side length of a1; one set of opposite corners of the square patch is chamfered, the shape of the chamfer is an isosceles right triangle, and the right angle side of the chamfer is a2, which realizes the circular polarization of the antenna; the other set of opposite corners is rounded, and the radius of the rounded corner is R1. The miniaturization of the upper dielectric is realized by optimizing the parameter of the rounded corner radius R1. Figure 4 As shown in (b).

[0038] The specific principle of achieving circular polarization is as follows: perturbations can be generated by chamfering. Based on the parameter characteristics of the upper dielectric 21, a suitable simplified mode is separated by optimizing the design of the square patch size a1 and the chamfer size a2, thereby achieving circular polarization in the low-frequency band of the operating frequency band. The selection of the chamfer position depends on the direction of the circular polarization wave. When the chamfer is at the upper left and lower right corners, a right-hand circular polarization wave is generated. When the chamfer is at the upper right and lower left corners, a left-hand circular polarization wave is generated.

[0039] In this embodiment, the upper dielectric 21 is selected from a material with, but not limited to, a dielectric constant ε. r A microwave laminate with a dielectric thickness of h1 = 2.55 mm, a dielectric thickness of h1 = 1.52 mm, and a loss tangent of tanδ1 = 0.0019, has an upper patch 22 with a thickness of 1 oz.

[0040] refer to Figure 5 The lower radiator 3 comprises five layers: the first layer includes a lower patch 31 and a metal ring 32; the second layer includes a middle dielectric 33, a metal ring post 34, and a shorting pin 35; the third layer includes a feed line 36; the fourth layer includes a lower dielectric 37 and a via 38; and the fifth layer is a ground plane 39. Figure 5 As shown in (a), the back of the ground plane 39 has a circular through hole 391. The diameter of the circular through hole 391 is larger than the inner conductor diameter of the antenna rear feed connector and smaller than the outer conductor diameter of the feed connector. Figure 5 As shown in (b).

[0041] The metal ring 32 is used to weld to the inner conductor of the rear power supply connector. Its geometric center is on the same vertical axis as the metal ring post 34, the through hole 38 and the circular through hole 391. One end of the feed line 36 is connected to the metal ring post 34 and the other end is connected to the shorting pin 35.

[0042] The ground plane 39 is connected to the outer conductor of the feed connector at the rear end of the antenna. The inner conductor of the feed connector passes through the through hole 391 and is connected to the metal ring 32 of the lower radiator, so that there is an open circuit between the outer conductor and the inner conductor of the feed connector, ensuring that the feed connector works normally.

[0043] The lower patch 31 is a square patch with a side length of a3. One set of its diagonals is chamfered, forming isosceles right triangles with legs of length a4. The chamfering direction is consistent with that of the upper patch 22 to ensure consistent antenna polarization. The other set of diagonals is rounded with a radius R2, and the rounding direction is consistent with that of the upper patch 22. This square patch has circular through-holes for isolation from the metal ring 32, and a set of opposite sides are connected to rectangular microstrip lines of length L1 and width W1, such as... Figure 5 As shown in (c), perturbations are generated by chamfering. Based on the parameter characteristics of the middle layer dielectric 33 and the lower layer dielectric 37, a suitable simplified mode is separated by optimizing the design of the square patch size a3 and the chamfer size a4, thereby realizing the circular polarization of the antenna in the mid- and high-frequency bands. The lower radiator is miniaturized by optimizing the fillet R2, and the impedance matching characteristics are improved by adjusting the length L1 and width W1 of the rectangular microstrip line.

[0044] The feed line 36 is a rectangular line with a length of L2 and a width of W2. Based on the parameter characteristics of the underlying dielectric 37, the mid-frequency band characteristics of the antenna are optimized by adjusting the feed line length L2 and width W2. The feed line length L2 is not less than the distance between the metal ring post 34 and the shorting pin 35; the initial value of the feed line width W2 is given according to the microstrip line characteristic impedance formula, and its calculation formula is as follows:

[0045]

[0046] in,

[0047] In the formula, Z0 represents the characteristic impedance of the microstrip line, and ε r W2 represents the dielectric constant of the microwave laminate, and h represents the thickness of the microwave laminate; the final value of W2 is determined by simulation optimization.

[0048] In this embodiment, the dielectric material selected is, but is not limited to, a material with a dielectric constant ε. r A microwave laminate with a dielectric thickness of h2 = 2.55 mm and a loss tangent of tanδ2 = 0.0019 mm; the lower dielectric layer is selected from materials with, but not limited to, dielectric constant ε. r A microwave laminate with a dielectric thickness of h3 = 2.55 mm, a dielectric thickness of h3 = 1.52 mm, and a loss tangent of tanδ3 = 0.0019; the thickness of the lower patch, metal ring, feed line, and ground plane is 1 oz. The diameter of the circular through-hole 391 is, but not limited to, 4 mm. The feed position is center-fed, that is, the center of the metal ring 32 is located at the geometric center of the lower radiator 3. The diameter of the inner conductor of the feed connector is, but not limited to, 1.3 mm. The optimal outer diameter of the metal ring 32 is 1.8 to 2.2 times the inner diameter. The initial value of the outer diameter φ4 of the metal ring 32 is, but not limited to, 2.6 mm. The inner diameter of the metal ring post 34 and the diameter of the through-hole 38 are the same, but not limited to, 1.3 mm. The shorting pin 35 is a metal post or a metal ring post with an inner diameter of, but not limited to, 1 mm.

[0049] refer to Figure 6 The antenna mount 4 is a metal mount with an air cavity structure, used to fix the radome, upper radiator, and lower radiator. It includes three mounting surfaces: a first mounting surface 41, a second mounting surface 42, a third mounting surface 43, and a metal mount 44. The first mounting surface 41 fixes the upper radiator 2, the second mounting surface 42 fixes the lower radiator 3, and the third mounting surface 43 fixes the radome 1. The antenna performance can be optimized by adjusting the parameters of the outer diameter φ5 of the first mounting surface 41, the diameter φ6 of the air cavity, and the height h4 of the air cavity.

[0050] Combination Figures 1 to 6 The working principle of this utility model is as follows:

[0051] This novel antenna employs a single-feed configuration, generating two spatially orthogonal linearly polarized waves with equal amplitude and a 90° phase difference to achieve circular polarization. It utilizes a multi-layer structure to achieve wideband characteristics, dividing the operating frequency band into three segments: low-frequency, mid-frequency, and high-frequency. Adjusting the upper patch 22 optimizes the low-frequency characteristics, adjusting the feed line 36 optimizes the mid-frequency characteristics, and adjusting the lower patch 31 optimizes the high-frequency characteristics.

[0052] When the antenna is in the transmitting state, the signal transmitted by the rear radar equipment passes through the inner conductor of the rear feed connector, through the antenna mount 4, ground plane 39, lower dielectric 37, and connects to the metal ring 32 for contact feeding; then the signal flows through the metal ring 32 through the metal ring post 34, feed line 36, and shorting pin 35 to the lower patch 31; the signal generates excitation in the lower patch 31 to form an electromagnetic wave and couples through the air cavity of the antenna mount 4 to the upper patch 22 to generate a coupled electromagnetic wave; the two are superimposed and radiated outward through the upper dielectric 21 and the antenna cover 1.

[0053] When the antenna is in receiving mode, electromagnetic waves pass through the antenna cover 1 and the upper dielectric 21 to reach the upper patch 22, and are coupled to the lower patch 31 through the air cavity of the antenna mount 4. Then, they pass through the short-circuit pin 35, the feed line 36, and the metal ring post 34 to reach the metal ring 32, and finally reach the back-end radar equipment through the feed probe.

[0054] The effectiveness of this invention can be further illustrated by the following simulation results.

[0055] I. Simulation Conditions

[0056] Condition 1: Using HFSS electromagnetic simulation software, establish electromagnetic simulation model A of the embodiment of this utility model.

[0057] The structural parameters are set as follows:

[0058] Radome: The inner diameter φ1 of the radome is 98mm;

[0059] Upper radiator: The diameter φ2 of the upper dielectric 21 is 96mm and the thickness h1 is 1.52mm; the side length a1 of the upper patch 22 is 66.2mm, the right-angled side a2 of the right triangle in the chamfer is 12mm, and the chamfer radius R1 is 8mm;

[0060] Lower radiator: The side length a3 of the lower patch 31 is 54.5mm, the right-angled side a4 of the chamfered right triangle is 11mm, the chamfer radius R2 is 6mm, the length L1 of the rectangular line is 9mm, and the width W1 is 13mm; the diameter φ4 of the metal ring 32 is 2.6mm; the diameter φ3 of the middle dielectric 33 is 88mm, and the thickness h2 is 2.36mm; the length L2 of the feed line is 30.1mm, and the width W2 is 4.8mm; the thickness h3 of the lower dielectric is 1.52mm.

[0061] Antenna mount: The outer diameter of the upper surface of the antenna mount is φ5, which is 98mm; the diameter of the air cavity is φ6, which is 90mm; and the height of the air cavity is h4, which is 12mm.

[0062] Condition 2: Using HFSS electromagnetic simulation software, replace the radiator in the multi-layer structure of this utility model embodiment with the following... Figure 7 An electromagnetic simulation model B is established for the single-layer lower radiator shown.

[0063] II. Simulation Content

[0064] Simulation 1: Under the above conditions, the standing wave ratio of the antenna simulation model A of this utility model is simulated, and the results are as follows. Figure 8 As shown.

[0065] from Figure 8 It can be seen that the standing wave ratio (SWR) of the antenna is 1.4934 at a frequency of 1.349 GHz and 1.4975 at a frequency of 1.5030 GHz. The maximum SWR in the 1.349 GHz to 1.503 GHz frequency band is 1.4975, corresponding to a frequency of 1.5030 GHz. Therefore, it can be concluded that the SWR of the antenna is less than 1.5 in the range of 1.349 GHz to 1.503 GHz.

[0066] Simulation 2: Under the above conditions, the standing wave ratio of the existing single-layer radiator structure antenna simulation model B is simulated, and the results are as follows: Figure 9 As shown.

[0067] from Figure 9 It can be seen that the antenna has a standing wave ratio (SWR) of 1.4835 at 1.351 GHz and 1.4864 at 1.395 GHz, with a maximum SWR of 1.4864 within the 1.351 GHz to 1.395 GHz band, corresponding to a frequency of 1.395 GHz. Similarly, the SWR is 1.4895 at 1.446 GHz and 1.4816 at 1.504 GHz, with a maximum SWR of 1.4895 within the 1.446 GHz to 1.504 GHz band, corresponding to a frequency of 1.446 GHz. Therefore, it can be concluded that the SWR of the antenna is no greater than 1.5 within the 1.351 GHz to 1.395 GHz and 1.446 GHz to 1.504 GHz ranges.

[0068] contrast Figure 8 and Figure 9 As can be seen, the broadband circularly polarized antenna with adjustable feed position of this utility model has a working frequency band of 10.79% with a standing wave ratio of less than 1.5, while the existing antennas with a standing wave ratio of less than 1.5 have a working frequency band of 7.15%. This utility model broadens the antenna's working bandwidth by 3.64%.

[0069] Simulation results show that this invention can both adjust the antenna feed position from offset feed to center feed and broaden the antenna bandwidth, thus exhibiting wideband characteristics.

[0070] The above description is merely a specific example of this utility model and does not constitute any limitation on this utility model. Obviously, those skilled in the art, after understanding the content and principle of this utility model, may make various modifications and changes in form and details without departing from the principle and structure of this utility model. However, these modifications and changes based on the concept of this utility model are still within the protection scope of the claims of this utility model.

Claims

1. A broadband circularly polarized antenna with adjustable feed position, comprising a radome (1), an upper radiator (2), a lower radiator (3), and an antenna base (4), characterized in that: the lower radiator (3) comprises five layers from top to bottom, the first layer comprises a lower patch (31) and a metal ring (32); the second layer comprises a middle layer dielectric (33), a metal ring column (34), and a short-circuit pin (35); the third layer comprises a feed line (36); the fourth layer comprises a lower layer dielectric (37) and a through hole (38); the fifth layer comprises a ground plate (39), one end of the feed line (36) is connected with the metal ring (32) through the metal ring column (34), and the other end is connected with the lower patch (31) through the short-circuit pin (35); the upper radiator (2) and the lower radiator (3) are both fixed on the antenna base (4), and the upper radiator (2) and the lower radiator (3) are provided with multiple adjustable parameters, which together with the parameters of the antenna base (4) adjust the circular polarization characteristics of the antenna.

2. The antenna according to claim 1, characterized in that, the lower patch (31) is a square patch with a side length of a3, one set of diagonals of the square patch is a cut angle, and the shape of the cut angle is an isosceles right triangle, which is used to realize the circular polarization of the antenna; the other set of diagonals is a rounded corner, which is used to realize the miniaturization of the antenna; the square patch has a circular through hole, and one set of opposite sides is connected with a rectangular microstrip line, which is used to adjust the impedance matching of the antenna.

3. The antenna of claim 1, characterized in that: the optimal outer diameter of the metal ring (32) is 1.8-2.2 times the inner diameter; the inner diameter of the metal ring column (34) is the same as the diameter of the through hole (38).

4. The antenna of claim 1, wherein: the feed line (36) is a rectangular structure, the length L2 is not less than the distance between the metal ring column (34) and the short-circuit pin (35), and the width W2 is given an initial value according to the characteristic impedance formula of the microstrip line and is determined as a final value through simulation optimization.

5. The antenna according to claim 1, wherein, the upper radiator (2) comprises an upper layer dielectric (21) and an upper patch (22) from top to bottom; the upper patch (22) is a square patch with a side length of a1, and the side length a1 is greater than the side length a3 of the lower patch (31); one set of cut angles of the upper patch (22) is an isosceles right triangle, and the direction of the cut angle is consistent with that of the lower patch (31); the other set of rounded corners is consistent with the direction of the rounded corners of the lower patch (31).

6. The antenna according to claim 1, wherein, the adjustable parameters of the upper radiator (2) include the thickness h1 of the upper layer dielectric, the side length a1 of the upper patch, the length a2 of the right angle side of the cut angle, and the radius R1 of the rounded corner, and the optimization of the low-frequency band characteristics of the antenna is realized by adjusting these parameters.

7. The antenna according to claim 1, wherein, the adjustable parameters of the lower radiator (3) include the side length a3 of the lower patch, the length a4 of the right angle side of the cut angle, the radius R2 of the rounded corner, the length L1 and the width W1 of the rectangular line, the diameter φ4 of the metal ring, the diameter φ3 and the thickness h2 of the middle layer dielectric, the length L2 and the width W2 of the feed line, and the thickness h3 of the lower layer dielectric, the optimization of the medium-frequency characteristics of the antenna is realized by adjusting the thickness h3 of the lower layer dielectric, the length L2 and the width W2 of the feed line, and the optimization of the high-frequency characteristics of the antenna is realized by adjusting the remaining parameters.

8. The antenna according to claim 1, wherein, the antenna base (4) is a metal base with an air cavity structure, which is used to fix the radome, the upper radiator, and the lower radiator. It includes three installation surfaces (41, 42, 43) and a metal base (44); wherein the first installation surface (41) is used for fixing the upper radiator, the second installation surface (42) is used for fixing the lower radiator, and the third installation surface (43) is used for fixing the antenna cover; the outer diameter φ5 of the first installation surface (41), the air cavity diameter φ6 and the air cavity height h4 are adjusted to realize optimization of the antenna performance.

9. The antenna according to claim 1, wherein, The inner diameter size φ1 of the antenna cover (1) is consistent with the outer diameter φ5 size of the first installation surface (41); the material of the antenna cover (1) is a wave-transparent material and needs to meet the use environment requirement; and the thickness of the antenna cover (1) is calculated according to the initial value of the optimal wave-transparent formula under the premise of meeting the structural strength and is determined as the final value through simulation optimization.

10. The antenna according to claim 1, wherein, The ground plate (39) is provided with a circular through hole (391) on the upper surface, the diameter of the through hole is greater than the inner conductor diameter of the antenna rear end feed connector and is less than the outer conductor diameter of the feed connector; the ground plate (39) is connected with the outer conductor of the feed connector at the rear end of the antenna, the inner conductor of the feed connector passes through the circular through hole (391) and is connected with the metal ring (32) of the lower radiator, so that the outer conductor and the inner conductor of the feed connector are open-circuited, and normal work of the feed connector is ensured.

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