An ultra-wideband tightly coupled array antenna based on third-order slotline radiating arms

Abstract

The present invention discloses an ultra-wideband tightly coupled array antenna based on a third-order slot line radiating arm, comprising M×N array-distributed antenna units, wherein M×N≥2, M and N are both positive integers, wherein each antenna unit comprises a dielectric plate, a third-order slot line radiating arm and a floor; the dielectric plate is vertically connected to the top of the floor, and the third-order slot line radiating arm is arranged on one side of the dielectric plate; the third-order slot line radiating arm is composed of two left-right symmetrical but unconnected units, each unit being a rectangular metal patch etched with three arc segments on the inner side, the inner side refers to the side where the two units are close; the size parameters of the three arc segments are different. The present invention can expand the bandwidth of the antenna, realize the working characteristics of low profile and wide-angle scanning, and reduce the difficulty of processing.

Description

Technical Field

[0001] The invention belongs to the field of antenna technology, and relates to a wideband bandwidth angle scanning array antenna, and in particular to an ultra-wideband tightly coupled array antenna based on a third-order slot line radiation arm, which can be used for wireless communication and multi-function radar systems. Background Art

[0002] With the increasing development of modern wireless communication systems, the demand for radar systems with integrated functions such as detection, interference, detection and communication is becoming increasingly urgent, and the corresponding requirements for antenna performance are also getting higher and higher, which requires the antenna to have a wide working bandwidth, large-angle beam scanning and low profile. The broadband array antenna based on tight coupling technology has excellent characteristics such as broadband, wide-angle scanning and low profile. Therefore, further research on ultra-wideband tightly coupled array antennas is of great significance to the field of radar antennas.

[0003] Patent CN109216940A discloses an ultra-wideband tightly coupled array antenna, which includes a first matching layer, a second matching layer, an antenna array board, a frequency selective surface board and a feed balun array. The antenna array board is composed of multiple dipole radiation periodic units, and uses tight coupling between units to meet the standing wave ratio of less than 3 in the 1.14GHz to 11.2GHz frequency band. The array bandwidth can be increased to 9.8 times the frequency, which can be used for communication and satellite tracking radar systems. However, the phase scanning angle of the array antenna is not very large, and the structure is relatively complex, which is not easy to process.

[0004] Patent CN113078460A discloses a high-isolation dual-polarization tightly coupled phased array antenna unit based on a slot-coupled structure. The antenna proposes a slot-coupled transition structure, which optimizes the polarization isolation of the antenna while ensuring the standing wave and radiation performance of the phased array antenna, and can achieve ±60° beam scanning on the E and H planes. However, the working bandwidth of the antenna is only twice the frequency, which is not suitable for multi-function radar systems. Summary of the invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide an ultra-wideband tightly coupled array antenna based on a third-order slotline radiating arm to expand the bandwidth of the antenna, achieve low-profile and wide-angle scanning working characteristics, and reduce processing difficulty.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] An ultra-wideband tightly coupled array antenna based on a third-order slotline radiating arm comprises M×N array-distributed antenna units, wherein M×N≥2, M and N are both positive integers, wherein each of the antenna units comprises a dielectric plate, a third-order slotline radiating arm and a floor; the dielectric plate is vertically connected to the top of the floor, and the third-order slotline radiating arm is arranged on one side of the dielectric plate; the third-order slotline radiating arm consists of two left-right symmetrical but unconnected units, each unit is a rectangular metal patch with three arc sections etched on the inner side, and the inner side refers to a side where two units are close to each other; and the size parameters of the three arc sections are different.

[0008] In one embodiment, the three arcs are three exponential curves with the same parameter equation, and the convex sides of the arcs face the symmetry lines of the two units.

[0009] In one embodiment, the parameter equation is as follows:

[0010]

[0011] In the formula, t is the parameter, v s is the horizontal coordinate of the starting point, v e is the abscissa of the end point, h is the height difference between the starting point and the end point, k is the slope of the curve, k∈[0,+∞), and the slopes of the three arcs are all 0.1.

[0012] In one embodiment, the three arcs, the upper arc, the middle arc and the lower arc, have heights and widths that decrease successively. The height is the vertical distance between the two ends of the arc, and the width is the horizontal distance between the two ends of the arc.

[0013] In one embodiment, the heights of the upper arc, the middle arc and the lower arc are h3=4mm, h2=3mm, h1=1mm, and the widths are v3=3mm, v2=2mm, v1=1.5mm, respectively. The distance between the lower ends of the two units is gap=0.7mm.

[0014] In one embodiment, the ultra-wideband tightly coupled array antenna also includes periodic metal patches and embedded metal narrow strips arranged on a dielectric plate; the periodic metal patches are located above the third-order slot line radiation arms, and are composed of a plurality of rectangular metal patches of the same size arranged at equal intervals; the embedded metal narrow strips are located between the two units, and are composed of 2K rectangular metal patches arranged symmetrically in pairs to form K pairs, and each pair of rectangular metal patches has the same symmetry line as the two units.

[0015] In one embodiment, the periodic metal patches are arranged in two groups, each group is composed of four rectangular metal patches arranged at equal intervals, wherein the first group of periodic metal patches is arranged on one side of the dielectric plate, and the second group of periodic metal patches is arranged on the other side of the dielectric plate; the embedded metal strip is composed of six rectangular metal patches arranged symmetrically in pairs, that is, K=3, and the six rectangular metal patches are arranged on the same side of the dielectric plate.

[0016] In one embodiment, the ultra-wideband tightly coupled array antenna further includes a broadband feeding balun disposed on a dielectric board, and the broadband feeding balun is located between the third-order slotline radiation arm and the floor.

[0017] In one embodiment, the height of the bottom of the third-order slot line radiation arm from the floor is Hd=10mm, and the spacing between the top and the periodic metal patch is Ddf=0.2mm; in the periodic metal patch, the length of each rectangular metal patch is Lf1=3mm, the width is Wf1=1mm, and the spacing between two groups of periodic metal patches is Df1=0.1mm; in the embedded metal narrow strip, the lengths of the upper pair of rectangular metal patches, the middle pair of rectangular metal patches and the lower pair of rectangular metal patches are Lf2=3.3mm, Lf3=2.8mm and Lf4=1mm respectively. The widths are Wf2=1mm, Wf3=1mm and Wf4=1mm respectively, and the spacing between each pair of rectangular metal patches is Df2=0.5mm; the broadband feeding balun is a microstrip line-slot line structure, and the widths of its straight metal microstrip lines are Wb1=0.4mm, Wb2=0.2mm, Wb3=0.1mm, and the lengths are Lb11=6.2mm, Lb12=2.2mm, Lb2=2mm, Lb3=1mm. The radius of its fan-shaped metal patch is rb1=2mm, the fan-shaped angle is 120°, and the diameter of the intermediate resonant cavity is rb2=2.8mm.

[0018] In one embodiment, the ultra-wideband tightly coupled array antenna also includes a U-shaped metal coupling slot placed perpendicular to the floor, and there are two U-shaped metal coupling slots, namely a first slot and a second slot that are symmetrically arranged on the left and right. Vertical slots are opened on the inner sides of the first slot and the second slot, and the two vertical edges of the dielectric plate are stuck in the two vertical slots.

[0019] The antenna of the present invention has an average active standing wave ratio of ≤3 in the working frequency band, the working frequency band covers a frequency range of 1.8 GHz to 10.8 GHz, and the E-plane and H-plane scanning ranges are ±45°.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention greatly expands the impedance bandwidth of the antenna through the third-order slot line radiation arm structure, and realizes the ultra-wideband working characteristics of the antenna.

[0022] 2. The present invention uses periodic metal patches and embedded metal narrow strips to replace traditional dielectric coatings, which can not only optimize the antenna standing wave ratio characteristics and increase the phase scanning angle of the antenna, but also greatly reduce the overall profile of the antenna and reduce the overall weight of the antenna.

[0023] 3. The present invention utilizes a U-shaped metal coupling slot to provide the coupling effect required to broaden the impedance bandwidth, and its connection with the floor can be regarded as a grounding short-circuit branch to suppress common-mode resonance, thereby reducing the design difficulty of a broadband feeding balun to a certain extent.

[0024] 4. The present invention prints two groups of periodic metal patches and a broadband feeding balun on both sides of the same dielectric board and places them between two U-shaped metal coupling slots fixed on the floor, thereby avoiding the use of other metasurface structures, simplifying the antenna structure, and reducing the difficulty of antenna processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the structure of the ultra-wideband tightly coupled array antenna of the present invention.

[0026] Figure 2 It is a schematic diagram of the array unit structure in the present invention.

[0027] Figure 3 for Figure 2 main view.

[0028] Figure 4 for Figure 2 Side view of.

[0029] Figure 5 Schematic diagram of the periodic metal patch structure in the present invention.

[0030] Figure 6 It is a schematic diagram of the embedded metal narrow strip structure in the present invention.

[0031] Figure 7 It is a schematic diagram of the structure of the third-order slot line radiation arm in the present invention.

[0032] Figure 8 Schematic diagram of the feeding balun structure in the present invention.

[0033] Fig. 9 It is a schematic diagram of the U-shaped metal coupling slot in the present invention.

[0034] Fig.10 The active standing wave ratio curve of the array antenna of the present invention when the E plane is scanned at 45°.

[0035] Fig.11 The active standing wave ratio curve of the array antenna of the present invention when the H-plane phase scan is 45°.

[0036] Fig.12 The main polarization and cross-polarization radiation patterns of the array antenna of the present invention when the E plane is swept 45° at 6.3 GHz.

[0037] Fig.13 The main polarization and cross-polarization radiation patterns of the array antenna of the present invention when the H-plane phase sweep is 45° at 6.3 GHz. DETAILED DESCRIPTION

[0038] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the embodiments and effects of the present invention are further described in detail below in conjunction with the accompanying drawings and embodiments:

[0039] like Figure 1 As shown, an ultra-wideband tightly coupled array antenna based on a third-order slotline radiating arm includes M×N array-distributed antenna units, or is composed of M×N antenna units distributed in an array, that is, adjacent array units are closely connected and arranged in sequence along the horizontal horizontal-vertical direction to form a periodic arrangement structure. Where M×N≥2, M and N are both positive integers. Figure 1 In the embodiment shown, M and N are both 10, thereby forming a 10×10 finite array, the length of the array unit is Dx=13.5 mm, the width is Dy=13.5 mm, and the surrounding circle is virtual elements.

[0040] Reference Figure 2 , Figure 3 and Figure 4 Each antenna unit mainly includes a dielectric plate 1, a third-order slot line radiation arm 4 and a floor 7, wherein the floor 7 is arranged horizontally, and the dielectric plate 1 is vertically connected to the top of the floor 7. The third-order slot line radiation arm 4 is arranged on one side of the dielectric plate 1 by printing or the like. The third-order slot line radiation arm 4 is composed of two units, which are symmetrical but not connected, that is, there is a space in the middle. Each unit is a rectangular metal patch with three arcs etched on the inner side. The inner side mentioned here refers to the side where the two units are close to each other; in the present invention, the size parameters of the three arcs are different from each other.

[0041] According to the structure of the present invention, by arranging a third-order slot line radiation arm 4 on the dielectric plate 1, a new resonance point is introduced at a high frequency by utilizing the third-order slot line radiation arm 4, which works together with the low-frequency tight coupling effect resonance point and the intermediate frequency quarter wavelength resonance point to realize the multi-resonance broadband principle, greatly expand the impedance bandwidth of the antenna, and realize the ultra-wideband working characteristics of the antenna.

[0042] The present invention utilizes a third-order slot-line radiation arm structure to achieve ultra-wideband operating characteristics. The provided ultra-wideband tightly coupled array antenna can achieve ±45° angular scanning of the E-plane and the H-plane within a 6-fold frequency operating bandwidth and has a low profile characteristic, and is suitable for wireless communications and multi-function radar systems.

[0043] In some embodiments of the present invention, the three arcs of the third-order slot line radiation arm 4 are represented by the parametric equation shown in formula (1), where t is a parameter variable, v is s is the horizontal coordinate of the starting point, v e is the abscissa of the end point, h is the height difference between the start point and the end point, k is the slope of the curve, k∈[0,+∞), and the slopes of the three arcs are all 0.1. The convex side of the arc faces the symmetry line of the two units.

[0044]

[0045] Among the three arcs of the third-order slot line radiation arm 4, the top arc is the upper arc, the middle arc is the middle arc, and the bottom arc is the lower arc. From top to bottom, the heights of the three arcs decrease successively, and the widths also decrease successively. The height here refers to the vertical distance between the two ends of an arc, and the width refers to the horizontal distance between the two ends of an arc.

[0046] The three arcs set by the parameters in this embodiment can be equivalently regarded as introducing a reactive component into the antenna equivalent circuit, thereby introducing a resonance point at a suitable frequency band, thereby achieving the purpose of expanding the impedance bandwidth.

[0047] In some embodiments of the present invention, the ultra-wideband tightly coupled array antenna further includes a periodic metal patch 2 and an embedded metal narrow strip 3, which are also arranged on the dielectric plate 1 by printing or other methods. The periodic metal patch 2 is located above the third-order slot line radiation arm 4 and has a vertical spacing. The periodic metal patch 2 is composed of a plurality of rectangular metal patches of the same size arranged at equal intervals. For example, each rectangular metal patch is arranged horizontally. The embedded metal narrow strip 3 is located in the space between two units of the third-order slot line radiation arm 4, and is composed of 2K rectangular metal patches arranged symmetrically in pairs to form K pairs, and each pair of rectangular metal patches has the same symmetry line as the two units.

[0048] In this embodiment, periodic metal patches 2 and embedded metal narrow strips 3 are used to replace the traditional dielectric coating. The coating loaded on the top of the antenna can be equivalently regarded as an impedance transformation line for matching the antenna with the air. The impedance transformation purpose of the traditional dielectric coating can be achieved by using regularly arranged metal patches. In addition, there is a capacitive coupling effect between the periodic metal patches in the metal coating, which has a compensatory effect on the mismatch caused by the increase in inductance during antenna scanning. This structure can not only optimize the antenna standing wave ratio characteristics and increase the phase scanning angle of the antenna, but also greatly reduce the overall profile of the antenna and reduce the overall weight of the antenna.

[0049] In this embodiment, reference Figure 5The periodic metal patch 2 can be further divided into two groups, each group is composed of four rectangular metal patches arranged at equal intervals, wherein the first group of periodic metal patches 21 is arranged on one side of the dielectric plate 1, and the second group of periodic metal patches 22 is arranged on the other side of the dielectric plate 1. Figure 6 The embedded metal strip 3 is further composed of six rectangular metal patches arranged symmetrically in pairs, that is, K=3. The six rectangular metal patches are arranged on the same side of the dielectric plate 1. In this embodiment, they are located on the same side as the first group of periodic metal patches 21.

[0050] In some embodiments of the present invention, the ultra-wideband tightly coupled array antenna also includes a broadband feeding balun 5, which is also set on the dielectric board 1 by printing or other means, and is specifically located between the third-order slot line radiation arm 4 and the floor 7.

[0051] In this embodiment, the broadband feeding balun 5 has ultra-wideband characteristics and good impedance transformation effect, which is suitable for the working characteristics of the above-mentioned ultra-wideband radiator, and finally realizes the impedance transformation of the radiator from 150Ω to 50Ω and balanced feeding of the two radiation arms.

[0052] In some embodiments of the present invention, the ultra-wideband tightly coupled array antenna further comprises a U-shaped metal coupling slot 6, which is placed perpendicular to the floor 7 and is used to install the dielectric plate 1 and provide the coupling effect required to broaden the impedance bandwidth. Fig. 9 There are two U-shaped metal coupling slots 6, namely a first slot 61 and a second slot 62 which are symmetrically arranged. Vertical slots are opened on the inner sides of the first slot 61 and the second slot 62, and two vertical edges of the dielectric plate 1 are stuck in the two vertical slots.

[0053] In this embodiment, the U-shaped metal coupling slot body is used to provide the coupling effect required to broaden the impedance bandwidth, and its connection with the floor can be regarded as a ground short-circuit branch to suppress common-mode resonance, which reduces the design difficulty of the broadband feeding balun to a certain extent. Specifically, the broadband feeding balun has an asymmetric structure and a semi-open microstrip line, which will cause the current at both ends of the output to be unbalanced, and ultimately each unit will have a net current in the vertical direction. When the units are arranged periodically, the net current will form a new resonant field to destroy the normal operation of the antenna. This phenomenon is called common-mode resonance, and the U-shaped metal coupling slot is equivalent to introducing a metal wall in the resonant field, shortening the wavelength of the common-mode resonant field, thereby moving the common-mode resonance point to a high frequency, and finally moving it out of the working frequency band.

[0054] To verify the effect of the present invention, in a specific embodiment of the present invention, the material of the dielectric plate 1 is RogersRO4350, whose relative dielectric constant is 3.66 and loss tangent is 0.004. Figure 3, thickness is 0.254mm, height Hpcb=19.2mm.

[0055] refer to Figure 3 The height of the bottom of the third-order slot line radiation arm 4 from the floor 7 is Hd=10 mm, and the distance between the top and the periodic metal patch 2 is Ddf=0.2 mm.

[0056] refer to Figure 5 In the periodic metal patch 2, the length of each group of four rectangular metal patches is Lf1 = 3 mm, the width is Wf1 = 1 mm, and the spacing between the two groups of periodic metal patches is Df1 = 0.1 mm.

[0057] refer to Figure 6 In the embedded metal strip 3, the lengths of the upper pair of rectangular metal patches, the middle pair of rectangular metal patches and the lower pair of rectangular metal patches are Lf2=3.3mm, Lf3=2.8mm and Lf4=1mm respectively, and the widths are Wf2=1mm, Wf3=1mm and Wf4=1mm respectively, and the spacing between each pair of rectangular metal patches is Df2=0.5mm.

[0058] Reference Figure 7 The heights of the upper arc, middle arc and lower arc of the third-order slot line radiation arm 4 are h3 = 4mm, h2 = 3mm, h1 = 1mm, respectively, and the widths are v3 = 3mm, v2 = 2mm, v1 = 1.5mm, respectively. The gap between the bottom ends of the two units is gap = 0.7mm.

[0059] Reference Figure 8 The broadband feeding balun 5 is a microstrip line-slot line structure. The straight metal microstrip line consists of three sections of microstrip lines. The first section of the microstrip line starts from the bottom and has two vertical and horizontal sections. Its width Wb1=0.4mm, the vertical section length Lb11=6.2mm, and the horizontal section length Lb12=2.2mm; the second section of the microstrip line is horizontally connected to the first section of the microstrip line and extends to the left. Its width Wb2=0.2mm and length Lb2=2mm. The third section of the microstrip line is horizontally connected to the second section of the microstrip line and extends to the left. Its width Wb3=0.1mm and length Lb3=1mm. The fan-shaped metal patch is horizontally connected to the third section of the microstrip line, and its radius rb1=2mm, and the fan-shaped angle is 120°. The radius of the intermediate resonant cavity is rb2=2.8mm.

[0060] Reference Fig. 9 The height of the U-shaped metal coupling slot 6 is Hu=19.2mm, the width is Wu1=2.5mm, Wu2=1mm, the slot gap gapu=0.65mm, and the gap between each U-shaped metal coupling slot 6 and the dielectric plate 1 is 0.2mm.

[0061] The effect of the present invention can be further illustrated by the following simulation:

[0062] Simulation 1: The high-frequency structure simulation software HFSS is used to simulate the active standing wave ratio of the array antenna of the embodiment of the present invention when the E plane is scanned at 45°. The results are as follows: Fig.10 .

[0063] Simulation 2, using high-frequency structure simulation software HFSS to simulate the active standing wave ratio of the array antenna of the embodiment of the present invention when the H plane is scanned at 45°, the results are as follows: Fig.11 .

[0064] Simulation 3, using high-frequency structure simulation software HFSS to simulate the main polarization and cross-polarization patterns of the array antenna of the embodiment of the present invention when the E plane is swept 45° at 6.3GHz, the results are as follows: Fig.12 .

[0065] Simulation 4, using high-frequency structure simulation software HFSS to simulate the main polarization and cross-polarization patterns of the array antenna of the embodiment of the present invention when the H plane is swept 45° at 6.3GHz, the results are as follows: Fig.13 .

[0066] in: Fig.10 and Fig.11 The vertical axis represents the active standing wave ratio of the antenna, and the horizontal axis represents the frequency in GHz; Fig.12 and Fig.13 The polar coordinate represents the normalized gain of the array antenna in dB, and the polar coordinate represents the scanning angle in deg.

[0067] from Fig.10 and Fig.11 It can be seen that the active standing wave ratio of the antenna is ≤3 within the working frequency band, and the working frequency band covers the frequency range of 1.8 GHz to 10.8 GHz;

[0068] from Fig.12 and Fig.13 It can be seen that the E-plane and H-plane scanning range of the antenna is ±45°.

[0069] In summary, the operating bandwidth of the ultra-wideband dual-polarization tightly coupled array antenna of the present invention can reach 6 times the frequency, and a large-angle phase scanning of ±45° is achieved on the E-plane and H-plane, and a low-profile design is achieved, which is suitable for wireless communications, multi-function radar, electronic countermeasures and other fields.

[0070] The above is a detailed introduction to the ultra-wideband tightly coupled array antenna based on the third-order slotline structure provided by the present invention, and the principles and implementation methods of the present invention are explained and implemented using detailed structural design parameters. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention, and these improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An ultra-wideband tightly coupled array antenna based on a third-order slotline radiating arm, comprising M×N array-distributed antenna units, wherein M×N≥2, M and N are both positive integers, characterized in that: Each of the antenna units comprises a dielectric plate (1), a third-order slot line radiation arm (4) and a floor (7); the dielectric plate (1) is vertically connected to the top of the floor (7), and the third-order slot line radiation arm (4) is arranged on one side of the dielectric plate (1); the third-order slot line radiation arm (4) is composed of two left-right symmetrical but unconnected units, each unit being a rectangular metal patch with three arc sections etched on the inner side, the inner side referring to a side where two units are close to each other; the three arc sections have different size parameters; The three arcs are three exponential curves with the same parametric equation, and the convex side of the arc faces the symmetry line of the two units. The parametric equation is as follows: In the formula, t is the parameter, v s is the horizontal coordinate of the starting point, v e is the abscissa of the end point, h is the height difference between the start point and the end point, k is the slope of the curve, k∈[0,+∞), and the slopes of the three arcs are all 0.1; Among the three arcs, the heights of the upper arc, the middle arc and the lower arc decrease successively, and the widths decrease successively. The height is the vertical distance between the two ends of the arc, and the width is the horizontal distance between the two ends of the arc.

2. According to claim 1, the ultra-wideband tightly coupled array antenna based on the third-order slotline radiating arm is characterized in that: The heights of the upper arc, the middle arc and the lower arc are h3=4mm, h2=3mm, h1=1mm, respectively, and their widths are v3=3mm, v2=2mm, v1=1.5mm, respectively. The distance between the lower ends of the two units is gap=0.7mm.

3. According to claim 1, the ultra-wideband tightly coupled array antenna based on the third-order slotline radiating arm is characterized in that: The ultra-wideband tightly coupled array antenna also includes a periodic metal patch (2) and an embedded metal narrow strip (3) arranged on a dielectric plate (1); the periodic metal patch (2) is located above a third-order slot line radiation arm (4), and is composed of a plurality of rectangular metal patches of the same size arranged at equal intervals; the embedded metal narrow strip (3) is located between the two units, and is composed of 2K rectangular metal patches arranged symmetrically in pairs to form K pairs, and each pair of rectangular metal patches has the same symmetry line as the two units.

4. According to claim 3, the ultra-wideband tightly coupled array antenna based on the third-order slotline radiating arm is characterized in that: The periodic metal patches (2) are arranged in two groups, each group consisting of four rectangular metal patches arranged at equal intervals, wherein the first group of periodic metal patches (21) is arranged on one side of the dielectric plate (1), and the second group of periodic metal patches (22) is arranged on the other side of the dielectric plate (1); the embedded metal narrow strip (3) consists of six rectangular metal patches arranged symmetrically in pairs, that is, K=3, and the six rectangular metal patches are arranged on the same side of the dielectric plate (1).

5. According to claim 3, the ultra-wideband tightly coupled array antenna based on the third-order slotline radiating arm is characterized in that: The ultra-wideband tightly coupled array antenna also includes a broadband feeding balun (5) arranged on the dielectric plate (1), and the broadband feeding balun (5) is located between the third-order slot line radiation arm (4) and the floor (7).

6. The ultra-wideband tightly coupled array antenna based on a third-order slotline radiating arm according to claim 5, characterized in that: The height of the bottom of the third-order slot line radiation arm (4) from the floor (7) is Hd=10mm, and the distance between the top and the periodic metal patch (2) is Ddf=0.2mm; in the periodic metal patch (2), the length of each rectangular metal patch is Lf1=3mm, the width is Wf1=1mm, and the distance between two groups of periodic metal patches (2) is Df1=0.1mm; in the embedded metal narrow strip (3), the lengths of the upper pair of rectangular metal patches, the middle pair of rectangular metal patches and the lower pair of rectangular metal patches are Lf2=3.3mm, Lf3=2.8mm and Lf4= 1mm, the widths are Wf2=1mm, Wf3=1mm and Wf4=1mm respectively, and the spacing between each pair of rectangular metal patches is Df2=0.5mm; the broadband feeding balun (5) is a microstrip line-slot line structure, the widths of its straight metal microstrip lines are Wb1=0.4mm, Wb2=0.2mm, Wb3=0.1mm, the lengths are Lb11=6.2mm, Lb12=2.2mm, Lb2=2mm, Lb3=1mm, the radius of its fan-shaped metal patch is rb1=2mm, the fan-shaped angle is 120°, and the diameter of the middle resonant cavity is rb2=2.8mm.

7. The ultra-wideband tightly coupled array antenna based on a third-order slotline radiating arm according to claim 1, characterized in that: The ultra-wideband tightly coupled array antenna also includes a U-shaped metal coupling slot body (6) placed perpendicular to the floor (7), wherein the U-shaped metal coupling slot bodies (6) are two, namely a first slot body (61) and a second slot body (62) arranged symmetrically on the left and right, and vertical slots are formed on the inner side surfaces of the first slot body (61) and the second slot body (62), and the two vertical edges of the dielectric plate (1) are stuck in the two vertical slots.

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