Broadband wide-angle tight coupling dipole antenna array and antenna unit thereof

Abstract

The invention discloses a broadband wide-angle tight coupling dipole antenna array, each antenna unit is printed on a square dielectric plate, and the broadband wide-angle tight coupling dipole antenna array comprises a slotted frequency selective surface unit, a dipole antenna oscillator, a gradient microstrip balun, a short circuit patch and a metal ground structure. The slotted frequency selection surface units are printed on the front side and the rear side of the dielectric plate and located above the dipole antenna oscillator. The dipole antenna oscillator is of a symmetrical butterfly-shaped oscillator structure, is additionally provided with two coupling patches, is printed on the front side and the rear side of the dielectric plate, and is in mirror symmetry. The microstrip Balun adopts a gradual change structure design and is printed on the front side and the rear side of the dielectric plate, the upper part is connected with the dipole antenna oscillator, and the lower part is connected with the metal ground. The short-circuit patch is located at the rear side of the dielectric plate, the upper part is connected with the dipole antenna oscillator, and the lower part is connected with the metal ground. A dipole antenna oscillator and a gradient microstrip balun are adopted, and a slotted frequency selective surface unit structure is introduced, so that the antenna has the characteristics of integration, wide band, easiness in processing and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of antenna microwaves, and in particular relates to a wide-bandwidth-angle tightly coupled dipole antenna array and an antenna unit thereof. Background Art

[0002] Antennas serve as the channels for wireless signal transmission in electronic information systems, and their performance directly determines the system's performance. Phased array antennas are the predominant antenna type due to their compact size, flexible beam scanning, and strong anti-interference capabilities.

[0003] Phased array antenna design often begins with the antenna elements, first designing antenna elements that meet wide operating bandwidth requirements before proceeding to array assembly. During antenna assembly, mutual coupling between elements can affect the antenna's impedance matching. This deterioration in impedance matching can, in turn, affect the antenna's impedance bandwidth and phase scan angle. Traditional phased array antennas require measures to suppress mutual coupling between elements, which increases the array spacing and hinders miniaturization and high integration. Tightly coupled antenna arrays, on the other hand, exploit this mutual coupling effect to minimize element spacing. The capacitive reactance caused by tight coupling offsets the inductive reactance introduced by the floor, enabling the antenna array to maintain good impedance matching across a wide frequency band and scanning angle range, resulting in superior performance. Consequently, with increasing demands for antenna array integration and versatility, phased array antennas are required to possess wide-bandwidth and wide-angle scanning capabilities. Wide operating bandwidth and large scanning angles will be the primary trends in the future development of tightly coupled antennas.

[0004] Today’s tightly coupled antennas mainly adopt the dipole form, relying on the front-to-back overlap between adjacent dipoles, or the left-to-right interdigital structure to generate capacitive coupling to broaden the bandwidth, but this often leads to the appearance of impedance mismatch frequencies within the band, which in turn leads to deterioration of the antenna’s performance. In addition, in order to widen the scanning angle, the existing technology often adopts a structure in which a dielectric layer or metal patch is added above the antenna unit. However, in order to achieve a wide-angle scanning capability of ±60°, the additional dielectric layer needs to be thick enough, or the additional metal patch needs to be long enough, which will make the antenna unit heavier or have a higher profile, which is very unfavorable for the miniaturization and low-profile design of the tightly coupled antenna unit. Summary of the Invention

[0005] The purpose of the present invention is to provide a wide-bandwidth-angle tightly coupled dipole antenna array and its antenna unit, wherein the antenna unit adopts a symmetrical dipole antenna vibrator structure, and additionally has a slotted frequency selective surface unit and a short-circuit patch structure, so that the antenna unit has a wide-bandwidth-angle scanning capability while being miniaturized and low-profile.

[0006] In order to solve the above problems, the technical solution of the present invention is: A wide-bandwidth, wide-angle, tightly coupled dipole antenna array, comprising: a plurality of antenna units, wherein the antenna units are printed on a dielectric board; The antenna unit includes a slotted frequency selective surface unit, a dipole antenna element, a gradient microstrip balun, a short-circuit patch, and a metal ground. The dipole antenna element is disposed on a first surface and a second surface of a dielectric plate. The antenna element on each surface is connected to a gradient microstrip balun, and the gradient microstrip balun on one surface is connected to the metal ground. The first surface is opposite to the second surface. The slotted frequency selective surface unit is located above the dipole antenna element and is set with a periodic number to optimize the impedance matching performance of the antenna unit; The short-circuit patches are arranged on both sides of a surface of the dielectric plate, connecting the antenna element and the metal ground on the surface, shortening the current loop path, and optimizing the cross-polarization performance of the antenna unit.

[0007] According to an embodiment of the present invention, the slotted frequency selective surface unit is a periodic rectangular parallelepiped structure with a slot in the middle of the unit.

[0008] According to one embodiment of the present invention, the slotted frequency selective surface unit includes a first slotted frequency selective surface unit arranged on the first surface of the dielectric plate and a second slotted frequency selective surface unit arranged on the second surface of the dielectric plate, and the slot shapes of the first slotted frequency selective surface unit and the second slotted frequency selective surface unit are complementary.

[0009] According to one embodiment of the present invention, the dipole antenna element is a symmetrical butterfly-shaped element structure, which is separately arranged on the first surface and the second surface of the dielectric plate; the antenna element on each surface is provided with a rectangular wave-shaped strip groove, and the elements on both sides of the strip groove form a cross-toe coupling structure.

[0010] According to an embodiment of the present invention, the dipole antenna element includes a first element and a first coupling patch provided on a first surface of a dielectric plate, and a second element and a second coupling patch provided on a second surface of the dielectric plate; The first oscillator and the second coupling patch form front-to-back overlapping coupling, and the second oscillator and the first coupling patch form front-to-back overlapping coupling. Combined with the interdigital coupling structure, capacitive coupling is generated to broaden the operating frequency band of the antenna unit.

[0011] According to an embodiment of the present invention, the gradient microstrip balun includes a first microstrip line provided on a first surface of a dielectric plate and a second microstrip line provided on a second surface of the dielectric plate; The upper end of the first microstrip line is connected to the antenna element on the first surface, and the lower end is not connected to the metal ground; The upper end of the second microstrip line is connected to the antenna element on the second surface, and the lower end is connected to the metal ground.

[0012] According to an embodiment of the present invention, the first microstrip line is trapezoidal in shape, and its narrow end is connected to the antenna element on the first surface; The second microstrip line is in the shape of an exponential gradient curve, with a narrow end connected to the antenna element on the second surface and a wide end connected to the metal ground.

[0013] According to an embodiment of the present invention, the width of the upper end of the first microstrip line is the same as the width of the upper end of the second microstrip line, forming a parallel double-line structure; The width of the lower end of the first microstrip line is smaller than the width of the lower end of the second microstrip line, forming an unbalanced feeding structure; By changing the gradient of the second microstrip line, the impedance transformation of the antenna unit is adjusted to achieve the best impedance matching effect.

[0014] According to one embodiment of the present invention, the short-circuit patch is printed on both sides of the second surface of the dielectric plate, including a left short-circuit patch and a right short-circuit patch. The upper end of the left short-circuit patch is connected to the coupling patch on the second surface, and the lower end is connected to the metal ground; the upper end of the right short-circuit patch is connected to the antenna element on the second surface, and the lower end is connected to the metal ground.

[0015] An antenna unit includes: a dielectric plate, a slotted frequency selective surface unit, a dipole antenna element, a gradient microstrip balun, a short-circuit patch and a metal ground; The dipole antenna elements are respectively arranged on the first surface and the second surface of the dielectric plate, and the antenna elements on each surface are connected to a gradient microstrip balun, and the gradient microstrip balun on one surface is connected to the metal ground; the first surface is opposite to the second surface; The slotted frequency selective surface unit is located above the dipole antenna element and is set with a periodic number to optimize the impedance matching performance of the antenna unit; The short-circuit patches are arranged on both sides of a surface of the dielectric plate, connecting the antenna element and the metal ground on the surface, shortening the current loop path, and optimizing the cross-polarization performance of the antenna unit.

[0016] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art: The wide-bandwidth, tightly coupled dipole antenna array in one embodiment of the present invention utilizes both front-to-back overlap and left-to-right interdigital structures to generate capacitive coupling, enabling a wide operating frequency band. Furthermore, a short-circuit patch structure between the antenna elements and the metal ground plane achieves excellent impedance matching within the frequency band.

[0017] The slotted frequency selective surface unit attached above the antenna element has a simple structure and strong adjustability. Compared with the traditional wide-angle scanning layer, it is miniaturized, low-profile and easy to process, giving the antenna unit a large-angle scanning capability.

[0018] The antenna unit has the characteristics of high integration, wide angle and wide bandwidth, simple structure, reducing the difficulty of subsequent antenna array assembly and increasing the reliability of the antenna array. The wide-bandwidth and wide-angle tightly coupled dipole antenna array after array formation can be applied to broadband phased array radar systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of a wide bandwidth tightly coupled dipole antenna array in one embodiment of the present invention; Figure 2 Schematic diagram of the antenna unit structure in one embodiment of the present invention; Figure 3 Schematic diagram of the structure of a slotted frequency selection unit in one embodiment of the present invention; Figure 4 Schematic diagram of the structure after the left antenna element is connected to the front microstrip line in one embodiment of the present invention; Figure 5 Schematic diagram of the structure after the right antenna element, rear microstrip line and right short-circuit patch are connected in one embodiment of the present invention; Figure 6 is a normal voltage standing wave ratio curve diagram in one embodiment of the present invention; Figure 7 1 is a graph showing the E-plane wide-angle scanning standing wave ratio in one embodiment of the present invention; Figure 8 1 is a graph showing the standing wave ratio of an H-plane wide-angle scanning in an embodiment of the present invention; Figure 9 10 GHz E-plane wide-angle scanning pattern according to an embodiment of the present invention; Figure 10 1 is an H-plane wide-angle scanning pattern at a frequency of 10 GHz in one embodiment of the present invention. DETAILED DESCRIPTION

[0020] The wide bandwidth tightly coupled dipole antenna array proposed by the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description and claims.

[0021] First of all, it should be stated that, unless otherwise defined, the technical terms and scientific terms used in the present invention should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0022] Secondly, in the description of the present invention, the terms "upper", "lower", "front side", "rear side", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0023] like Figure 1 As shown, the present invention provides a wide-bandwidth, tightly coupled dipole antenna array comprising 16×16 antenna elements. The number of antenna elements can be determined based on actual requirements, and the size of the antenna elements can be designed to be 12mm×12mm×13.7mm.

[0024] like Figure 2 As shown, the antenna unit is printed on a square dielectric plate 1 and includes a slotted frequency selective surface (FSS) element 2, a dipole antenna element 3, a tapered microstrip balun 4, a shorting patch 5, and a metal ground 6. The dipole antenna element 3 is located on the first (front) and second (back) surfaces of the dielectric plate 1. The antenna element on each surface is connected to a tapered microstrip balun 4, while the tapered microstrip balun 4 on one surface is connected to the metal ground. The first and second surfaces are opposite each other. The slotted FSS element 2 is located above the dipole antenna element 3 and is arranged with a periodic number to optimize the antenna unit's impedance matching performance. Shorting patches 5 are located on both sides of one surface of the dielectric plate 1, connecting the antenna element on that surface to the metal ground. This shortens the current loop path and optimizes the antenna unit's cross-polarization performance.

[0025] For details, please see Figure 3 The slotted FSS unit 2 is located above the dipole antenna element 3 and is a periodic rectangular parallelepiped structure. It includes a front-surface slotted FSS unit 21 and a rear-surface slotted FSS unit 22 printed on the dielectric plate 1. The slotted FSS unit 2 has a slot in the middle of the unit, and the slots of the front-surface slotted FSS unit 21 and the rear-surface slotted FSS unit 22 have complementary shapes.

[0026] Furthermore, the slotted frequency selective surface element 2 has a width w1 = 2.1 mm, a length l1 = 3.5 mm, a thickness t1, and a spacing s1 = 0.3 mm. The number of periods affects the frequency selective surface's transmission and reflection of spatial waves, thereby affecting the antenna element's impedance matching performance and wide-angle scanning capability. In this embodiment, the slotted frequency selective surface element has a period of 5. A circular slot is dug in the middle of the rectangular parallelepiped structure, and the slots between the front and rear slotted frequency selective surface elements 21 and 22 complement each other. The inner slot of the front slotted frequency selective surface element 21 has a width w2 = 1.8 mm and a length l2 = 3.2 mm. A hole is dug in the middle with a width w4 = 0.6 mm and a length l4 = 0.8 mm. The inner slot of the rear slotted frequency selective surface element 22 has a width w3 = 1.2 mm and a length l3 = 2.5 mm. The slotted frequency selective surface unit 2 has a higher degree of design freedom, thereby optimizing the impedance matching performance of the antenna unit. The design of the slotted frequency selective surface unit 2 is not limited to the number of periods, number of slots, and slot width parameters used in this embodiment.

[0027] The dipole antenna element 3 in this embodiment has a symmetrical butterfly-shaped structure, wide at the sides and narrow in the middle. It includes a left dipole element 31 printed on the front surface of the dielectric plate 1 and a right dipole element 32 printed on the rear surface, as well as a right coupling patch 33 printed on the front surface and a left coupling patch 34 printed on the rear surface.

[0028] Furthermore, the left oscillator 31 on the front surface of the dielectric plate is mirror-symmetrical to the right oscillator 32 on the back surface. A rectangular wavy strip groove is cut in the middle of the left oscillator 31, forming an interdigital coupling structure with the oscillators on either side of the groove. A rectangular wavy strip groove is cut in the middle of the right oscillator 32, forming an interdigital coupling structure with the oscillators on either side of the groove. The right coupling patch 33 on the front surface of the dielectric plate 1 is mirror-symmetrical to the left coupling patch 34 on the back surface. Both the right coupling patch 33 and the left coupling patch 34 are vertically placed metal foil structures, the same height as the antenna oscillators. The right coupling patch 33 forms a front-to-back overlapping coupling with the left oscillator 31, while the left coupling patch 34 forms a front-to-back overlapping coupling with the right oscillator 32.

[0029] Please see Figure 4The left-side oscillator 31 is connected to the front microstrip line 41, and its thickness is t1 = 0.018mm. The antenna oscillator has a height of h1 = 5.2mm. A rectangular wave-shaped strip slot is opened in the middle of the oscillator, d1 = 0.5mm away from the left side of the antenna oscillator, and the slot width is d3 = 0.2mm. After the slot is opened, the oscillators on both sides of the slot form a cross-toe structure with a toe width of d2 = 0.5mm. The oscillator arm on the right side of the slot is butterfly-shaped. The oscillator arm can have a variety of shapes. This embodiment adopts a shape with one end wide and the other end relatively narrow, gradually transitioning from the wide side to the narrow side. The wide side is connected to the oscillator on the right side of the slot, and the narrow side is connected to the front microstrip line 41. The front microstrip line 41 is a trapezoidal structure with a lower end width of d4 = 2mm, an upper end width of d5 = 1mm, and a height of h2 = 6.6mm.

[0030] The tapered microstrip balun 4 in this embodiment comprises a front microstrip line 41 printed on the front surface of the dielectric plate 1 and a rear microstrip line 42 printed on the rear surface. The front microstrip line 41 is a trapezoidal structure with a narrow upper edge connected to the left oscillator 31 and a wide lower edge. A hole is drilled in the metal ground 6 to prevent the front microstrip line from connecting to the metal ground. The rear microstrip line 42 is a trapezoidal structure with exponentially tapered edges. The narrow upper edge connects to the right oscillator 32 and the wide lower edge connects to the metal ground 6.

[0031] The short-circuit patches 5 in this embodiment are printed on both sides of the rear surface of the dielectric plate 1. They are vertically arranged thin metal sheets and include a left short-circuit patch 51 and a right short-circuit patch 52. The upper end of the left short-circuit patch 51 is connected to the left coupling patch 34, and the lower end is connected to the metal ground 6. The upper end of the right short-circuit patch 52 is connected to the right oscillator 32, and the lower end is connected to the metal ground 6.

[0032] Please see Figure 5 The right-side oscillator 32, the rear microstrip line 42, and the right-side short-circuit patch 52 are connected. A rectangular wave-shaped slot is cut in the middle of the oscillator, mirroring the slot cut in the middle of the left-side oscillator 31. The width of the oscillator on the right side of the slot is d1, the slot width is d3, and the toe width is d2. The right-side short-circuit patch 52 is connected to the oscillator on the right side of the slot and has a width of d1 and a height of h3 = 4mm. The addition of the short-circuit patch shortens the current loop path, causing the currents on the front microstrip line 41 and the rear microstrip line 42 to oppose each other. Combined with the currents on the left and right short-circuit patches 51 and 52, the vertical currents in the antenna unit cancel each other out, ensuring good cross-polarization performance. At the same time, the addition of the short-circuit patch can shift the common-mode resonant frequency out of band, ensuring good impedance matching within the antenna unit. The left-side oscillator arm of the slot is butterfly-shaped, gradually transitioning from a wide side to a narrow side. The wide side connects to the oscillator on the left side of the slot, and the narrow side connects to the rear microstrip line 42. The rear microstrip line 42 has an upper width of d5 and a lower width of d6 = 8 mm, and is formed on both sides by two mirror-symmetrical exponential gradient curves C1 and C2.

[0033] The front and rear microstrip lines 41 and 42 have the same width at their upper ends, forming a parallel dual-line structure. The rear microstrip line 42 is wider at its lower end than the front microstrip line 41, forming an unbalanced feed structure. Changing the gradient of the exponential gradient curves on both sides of the rear microstrip line 42 adjusts the impedance transformation of the antenna unit, achieving optimal impedance matching. The simple microstrip gradient balun structure achieves both impedance transformation and unbalanced-to-balanced conversion, ensuring the wideband characteristics of the antenna unit.

[0034] Considering the independence of the antenna unit, this embodiment takes the antenna unit as an example. Figure 2 The antenna unit includes: a dielectric plate 1, a slotted frequency selective surface unit 2, a dipole antenna element 3, a tapered microstrip balun 4, a shorting patch 5, and a metal ground 6. The dipole antenna element 3 is disposed on the first and second surfaces of the dielectric plate 1. The antenna element on each surface is connected to a tapered microstrip balun 4. The tapered microstrip balun 4 on any surface is connected to the metal ground 6. The first surface is opposite the second surface. The slotted frequency selective surface unit 2 is located above the dipole antenna element 3 and is arranged with a periodic number to optimize the impedance matching performance of the antenna unit. The shorting patch 5 is disposed on both sides of one surface of the dielectric plate 1, connecting the antenna element on that surface to the metal ground, shortening the current loop path and optimizing the cross-polarization performance of the antenna unit.

[0035] The specific structure and function of the antenna unit are as described above and will not be repeated here.

[0036] The effect of the present invention can be further illustrated by the following simulation: like Figure 6 As shown in the figure, the antenna unit adopts a symmetrical butterfly dipole element and a tapered microstrip balun, and introduces a slotted frequency selective surface unit structure. In the range of 3.84~11.14GHz, the VSWR is less than 2, and the full-band matching is good.

[0037] like Figure 7 As shown in the figure, the wide-angle scanning performance of the antenna unit on the E-plane is simulated. The results show that the antenna unit meets the VSWR < 2 when the E-plane is scanned to ±45° in the full frequency band, and the VSWR < 3 when the E-plane is scanned to ±60°, and has good matching characteristics.

[0038] like Figure 8 As shown in the figure, the wide-angle scanning performance of the antenna unit in the H plane is simulated. The results show that the antenna unit meets the VSWR < 2 when the H plane is scanned to ±30° in the full frequency band, and the VSWR < 3 when the E plane is scanned to ±60°, which has good matching characteristics.

[0039] like Figure 9As shown in the figure, the E-plane wide-angle scanning pattern of the tightly coupled dipole antenna array at 10 GHz is simulated and normalized. The results show that when the tightly coupled dipole antenna array scans 0°~60° in the E-plane, its main lobe level is more than 10 dB greater than the side lobe level, and the antenna array has good wide-angle scanning performance.

[0040] like Figure 10 As shown in the figure, the H-plane wide-angle scanning pattern of the tightly coupled dipole antenna array at 10 GHz is simulated and normalized. The results show that when the tightly coupled dipole antenna array scans 0°~60° in the H-plane, its main lobe level is more than 10 dB greater than the side lobe level, and the antenna array has good wide-angle scanning performance.

[0041] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, if these changes fall within the scope of the claims of the present invention and their equivalents, they still fall within the scope of protection of the present invention.

Claims

1. A wide bandwidth tightly coupled dipole antenna array, characterized in that: include: A plurality of antenna units, wherein the antenna units are printed on a dielectric board; The antenna unit includes a slotted frequency selective surface unit, a dipole antenna element, a gradient microstrip balun, a short-circuit patch, and a metal ground. The dipole antenna element is disposed on a first surface and a second surface of a dielectric plate. The antenna element on each surface is connected to a gradient microstrip balun, and the gradient microstrip balun on one surface is connected to the metal ground. The first surface is opposite to the second surface. The slotted frequency selective surface unit is located above the dipole antenna element and is set with a periodic number to optimize the impedance matching performance of the antenna unit; The short-circuit patches are arranged on both sides of a surface of the dielectric plate, connecting the antenna element and the metal ground on the surface, shortening the current loop path, and optimizing the cross-polarization performance of the antenna unit.

2. The wide bandwidth tightly coupled dipole antenna array according to claim 1, wherein: The slotted frequency selective surface unit is a periodic rectangular parallelepiped structure with a slot in the middle of the unit.

3. The wide bandwidth tightly coupled dipole antenna array according to claim 2, wherein: The slotted frequency selective surface unit includes a first slotted frequency selective surface unit provided on the first surface of the dielectric plate and a second slotted frequency selective surface unit provided on the second surface of the dielectric plate. The slot shapes of the first slotted frequency selective surface unit and the second slotted frequency selective surface unit are complementary.

4. The wide bandwidth tightly coupled dipole antenna array according to claim 1, wherein: The dipole antenna element is a symmetrical butterfly-shaped element structure, which is separately arranged on the first surface and the second surface of the dielectric plate; the antenna element on each surface is provided with a rectangular wave-shaped strip groove, and the elements on both sides of the strip groove form a cross-toe coupling structure.

5. The wide bandwidth tightly coupled dipole antenna array according to claim 4, wherein: The dipole antenna element comprises a first element and a first coupling patch provided on the first surface of the dielectric plate, and a second element and a second coupling patch provided on the second surface of the dielectric plate; The first oscillator and the second coupling patch form front-to-back overlapping coupling, and the second oscillator and the first coupling patch form front-to-back overlapping coupling. Combined with the interdigital coupling structure, capacitive coupling is generated to broaden the operating frequency band of the antenna unit.

6. The wide bandwidth tightly coupled dipole antenna array according to claim 1, wherein: The gradient microstrip balun includes a first microstrip line provided on the first surface of the dielectric plate and a second microstrip line provided on the second surface of the dielectric plate; The upper end of the first microstrip line is connected to the antenna element on the first surface, and the lower end is not connected to the metal ground; The upper end of the second microstrip line is connected to the antenna element on the second surface, and the lower end is connected to the metal ground.

7. The wide bandwidth tightly coupled dipole antenna array according to claim 6, wherein: The first microstrip line is in a trapezoidal shape, and its narrow end is connected to the antenna element on the first surface; The second microstrip line is in the shape of an exponential gradient curve, with a narrow end connected to the antenna element on the second surface and a wide end connected to the metal ground.

8. The wide bandwidth tightly coupled dipole antenna array according to claim 7, wherein: The width of the upper end of the first microstrip line is the same as the width of the upper end of the second microstrip line, forming a parallel double-line structure; The width of the lower end of the first microstrip line is smaller than the width of the lower end of the second microstrip line, forming an unbalanced feeding structure; By changing the gradient of the second microstrip line, the impedance transformation of the antenna unit is adjusted to achieve the best impedance matching effect.

9. The wide bandwidth tightly coupled dipole antenna array according to claim 1, wherein: The short-circuit patch is printed on both sides of the second surface of the dielectric plate, including a left short-circuit patch and a right short-circuit patch. The upper end of the left short-circuit patch is connected to the coupling patch on the second surface, and the lower end is connected to the metal ground; the upper end of the right short-circuit patch is connected to the antenna element on the second surface, and the lower end is connected to the metal ground.

10. An antenna unit, characterized in that: include: Dielectric plate, slotted frequency selective surface unit, dipole antenna element, gradient microstrip balun, short-circuit patch and metal ground; The dipole antenna elements are respectively arranged on the first surface and the second surface of the dielectric plate, and the antenna elements on each surface are connected to a gradient microstrip balun, and the gradient microstrip balun on one surface is connected to the metal ground; the first surface is opposite to the second surface; The slotted frequency selective surface unit is located above the dipole antenna element and is set with a periodic number to optimize the impedance matching performance of the antenna unit; The short-circuit patches are arranged on both sides of a surface of the dielectric plate, connecting the antenna element and the metal ground on the surface, shortening the current loop path, and optimizing the cross-polarization performance of the antenna unit.

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