An ultrawideband dual-slot Vivaldi antenna for air-coupled radar

Abstract

This invention proposes an ultra-wideband dual-slot Vivaldi antenna for air-coupled radar, comprising a dielectric substrate, a gradient-opening slot, an elliptical opening slot, and a microstrip feed structure. A radiating patch is attached to the upper surface of the dielectric substrate. The gradient-opening slot is formed on the radiating patch, with a horn-shaped opening. Multiple elliptical opening slots are formed on the radiating patch and symmetrically arranged on both sides of the gradient-opening slot. Each elliptical opening slot is part of a complete ellipse, and the centers of multiple elliptical opening slots on the same side are gradually arranged along the centerline of the gradient-opening slot. The major axis of each elliptical opening slot forms an angle with the centerline of the gradient-opening slot. The microstrip feed structure is disposed on the lower surface of the dielectric substrate. The Vivaldi antenna of this invention improves the surface current distribution of the antenna, suppresses current backflow, reduces sidelobe energy, and concentrates energy in the main radiation direction, greatly improving the antenna's gain and directivity.

Description

Technical Field

[0001] This invention relates to the field of antenna technology, and more particularly to an ultra-wideband dual-slot Vivaldi antenna for air-coupled radar. Background Technology

[0002] Antennas, as tools for receiving and transmitting signals, play a vital role in wireless communication, radar applications, and microwave imaging. Particularly in air-coupled radar, the performance of the antenna directly impacts the radar system's detection accuracy, imaging quality, and target identification capabilities. The Vivaldi antenna, a planar, ultra-wideband tapered slotted antenna, offers advantages such as ultra-wideband capability, ease of integration, high gain, and good directivity, making it suitable for use in radio wave radar systems for wide-area monitoring or detection. Furthermore, the Vivaldi antenna can transmit data received by the air-coupled radar system at high speeds and communicate with ground equipment.

[0003] In existing technologies, current backflow occurs on the patch surface. Some current flows from the inside of the exponential gradient line to the edge of the patch, resulting in energy discontinuity, larger antenna sidelobes, increased antenna loss, decreased gain, weakened beam directivity, and affecting radiation and imaging effects. Summary of the Invention

[0004] In view of this, the present invention proposes an ultra-wideband dual-slot Vivaldi antenna for air-coupled radar to solve the technical problems mentioned in the background art, such as current backflow on the patch surface, large antenna sidelobes, resulting in increased antenna loss, decreased gain, weakened beam directivity, and affected radiation and imaging effects.

[0005] The technical solution of this invention is implemented as follows:

[0006] This invention provides an ultra-wideband dual-slot Vivaldi antenna for air-coupled radar, comprising a dielectric substrate, a gradient slot, an elliptical slot, and a microstrip feeding structure, wherein:

[0007] A radiation patch is attached to the upper surface of the dielectric substrate;

[0008] The gradient opening groove is formed on the radiating patch and has a trumpet-shaped opening.

[0009] Multiple elliptical opening slots are formed on the radiating patch and symmetrically arranged on both sides of the gradient opening slot. Each elliptical opening slot is part of the entire ellipse. The centers of multiple elliptical opening slots on the same side are arranged in a gradually changing direction along the center line of the gradient opening slot. The major axis of the elliptical opening slot has an angle with the center line of the gradient opening slot.

[0010] The microstrip feeding structure is disposed on the lower surface of the dielectric substrate.

[0011] Based on the above technical solutions, preferably, the centers of multiple elliptical opening grooves on the same side are arranged at intervals of a first distance along the x-direction and a second distance along the y-direction, with the x-direction parallel to the center line of the gradient opening groove and the y-direction perpendicular to the x-direction.

[0012] Based on the above technical solutions, preferably, the angle between the major axis of the elliptical opening groove and the y-direction is 25 to 29 degrees.

[0013] Based on the above technical solutions, preferably, the major axis and minor axis of each elliptical opening groove are equal.

[0014] Based on the above technical solutions, preferably, it also includes multiple gain units, which are disposed on the upper surface of the dielectric substrate and located in the region where the gradient opening groove is located. The gain units are made of subwavelength metamaterials.

[0015] Based on the above technical solutions, preferably, the gain unit includes a plurality of first rectangular blocks with gradually varying lengths and a second rectangular block. The centers of the plurality of first rectangular blocks are arranged in a straight line along a direction parallel to the center line of the gradually varying opening groove. The second rectangular block is located between the two middle first rectangular blocks, and the length direction of the second rectangular block is perpendicular to the center line of the gradually varying opening groove.

[0016] Based on the above technical solutions, preferably, the microstrip power supply structure adopts a T-type power divider. The microstrip power supply structure includes a first microstrip line, a second microstrip line, a third microstrip line, a fourth microstrip line, and a fan-shaped stub connected in sequence. The end of the first microstrip line is connected to two second microstrip lines. The second and fourth microstrip lines are both perpendicular to the first microstrip line. The third microstrip line is parallel to the first microstrip line. The fan-shaped stub is located at the end of the fourth microstrip line.

[0017] Based on the above technical solutions, preferably, the end of the first microstrip line and the connection point between it and the two second microstrip lines are provided with a V-shaped chamfer.

[0018] Based on the above technical solutions, preferably, the arc degree of the fan-shaped branch is 105 to 115 degrees.

[0019] Based on the above technical solutions, preferably, the material of the dielectric substrate is Rogers RT5880, with a dielectric constant of 2.2 and a thickness of 0.75 to 0.8 mm.

[0020] The ultra-wideband dual-slot Vivaldi antenna for air-coupled radar of the present invention has the following advantages over the prior art:

[0021] Beneficial effects:

[0022] (1) Multiple elliptical opening slots are formed on the radiating patch and symmetrically arranged on both sides of the gradient opening slot. Each elliptical opening slot is part of the entire ellipse. The centers of multiple elliptical opening slots on the same side are arranged in a gradually changing direction along the center line of the gradient opening slot. The major axis of the elliptical opening slot has an angle with the center line of the gradient opening slot, which improves the surface current distribution of the antenna, suppresses the current backflow phenomenon, reduces the sidelobe energy, concentrates the energy in the main radiation direction, and greatly improves the gain and directivity of the antenna.

[0023] (2) Multiple elliptical opening slots on the same side are arranged at intervals of a first distance along the x direction and a second distance along the y direction. The x direction is parallel to the center line of the gradient opening slots, and the y direction is perpendicular to the x direction. While increasing the antenna gain, the antenna operating bandwidth remains basically unchanged, avoiding the reduction of the low-frequency bandwidth of the antenna and improving the reliability of the device.

[0024] (3) The angle between the major axis of the elliptical opening slot and the y direction is 25 to 29 degrees. By setting this angle, the gain and directivity of the antenna are further improved, resulting in a better gain effect for the antenna.

[0025] (4) The gain unit is disposed on the upper surface of the dielectric substrate and located in the area where the gradient opening slot is located. The gain unit is made of subwavelength metamaterial and couples with the transmitted electromagnetic wave, thereby increasing the gain of the antenna in the 3.5-10.5GHz bandwidth and improving the radiation performance of the antenna in the mid-frequency band.

[0026] (5) A V-shaped chamfer is provided at the connection between the end of the first microstrip line and the two second microstrip lines, which improves the impedance matching of the antenna and lowers the low-frequency operating point without changing the antenna size, so as to meet the requirements of air-coupled radar for miniaturization.

[0027] (6) The arc degree of the fan-shaped branch is 105 to 115 degrees, which makes the impedance matching of the antenna better, the return loss lower, the radiation efficiency better, and improves the performance of the antenna. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1This is a schematic diagram of the front structure of the ultra-wideband dual-slot Vivaldi antenna (before the elliptical opening slots are cut) for air-coupled radar in an embodiment of the present invention.

[0030] Figure 2 This is a schematic diagram of the back side of the ultra-wideband dual-slot Vivaldi antenna (before the elliptical opening slots are cut) used for air-coupled radar in Embodiment 1 of the present invention.

[0031] Figure 3 This is a schematic diagram of the structure of the ultra-wideband dual-slot Vivaldi antenna (after cutting out elliptical opening slots) for air-coupled radar in Embodiment 1 of the present invention.

[0032] Figure 4 (a) and (b) are respectively the simulation optimization S11 curves of parameters qa and qb in the Vivaldi antenna in Embodiment 1 of the present invention;

[0033] Figure 5 A comparison chart of the S11 simulation curves of the original Vivaldi antenna, the antenna of Embodiment 1, and the antenna of Embodiment 2 in the embodiments of the present invention;

[0034] Figure 6 This is a comparison chart of the gain simulation curves of the original Vivaldi, the antenna of Embodiment 1, and the antenna of Embodiment 2 in the embodiments of the present invention;

[0035] Figure 7 This is a front view of the Vivaldi antenna in Embodiment 2 of the present invention;

[0036] Figure 8 This is a perspective view of the Vivaldi antenna in Embodiment 2 of the present invention;

[0037] Figure 9 This is a schematic diagram of the gain unit in Embodiment 2 of the present invention;

[0038] Figure 10 (a) and (b) are the S-parameter diagram and equivalent dielectric parameter diagram of the gain element of the Vivaldi antenna in Embodiment 3 of the present invention, respectively.

[0039] Figure 11 (a) and (b) are the front and back views of the actual antenna of Embodiment 3 of the present invention, respectively;

[0040] Figure 12 (a) and (b) are comparison diagrams of the S11 curves of the original Vivaldi antenna in the embodiment of the present invention and the simulation of the original Vivaldi antenna, respectively, and comparison diagrams of the S11 curves of the original Vivaldi antenna in embodiment 2 and the simulation of the Vivaldi antenna in embodiment 2.

[0041] Figure 13 The diagram shows a comparison of the gain of the original antenna simulation and the physical antenna in the embodiments of the present invention, and the antenna simulation and the physical antenna in Embodiment 2.

[0042] Figure 14 (a) and (b) in the figure are the simulated XOY plane radiation patterns of the original antenna, the antenna of Example 1, and the antenna of Example 2 at 4.5 GHz, respectively, and the XOY plane radiation patterns of the physical original antenna and the physical antenna of Example 2 at 4.5 GHz.

[0043] Figure 15 (a) and (b) in the figure are the simulated XOY plane radiation patterns of the original antenna, the antenna of Example 1, and the antenna of Example 2 at 6.5 GHz, respectively, and the XOY plane radiation patterns of the physical original antenna and the physical antenna of Example 2 at 6.5 GHz.

[0044] Figure 16 (a) and (b) in the figure are the simulated XOY plane radiation patterns of the original antenna, the antenna of Embodiment 1, and the antenna of Embodiment 2 at 8.0 GHz, respectively, and the XOY plane radiation patterns of the physical original antenna and the physical antenna of Embodiment 2 at 8.0 GHz.

[0045] Explanation of reference numerals in the attached figures:

[0046] 1-Dielectric substrate; 2-Gradual opening slot; 3-Microstrip feeding structure; 4-Rectangular opening slot; 5-Circular slot; 6-Elliptical opening slot; 7-Gain unit. Detailed Implementation

[0047] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0048] Example 1

[0049] Reference Figure 1-16 As shown in the embodiment of the present invention, an ultra-wideband dual-slot Vivaldi antenna for air-coupled radar is proposed, comprising a dielectric substrate 1, a gradient opening slot 2, an elliptical opening slot 6, and a microstrip feed structure 3, wherein:

[0050] A radiation patch is attached to the upper surface of the dielectric substrate 1; the dielectric substrate 1 is made of Rogers RT5880, has a dielectric constant of 2.2, a thickness of 0.75-0.8 mm, preferably 0.787 mm, a substrate width wb = 86 mm, and a board length of 130 mm.

[0051] The gradient opening slot 2 is formed on the radiating patch and has a horn-shaped opening. Specifically, the gradient opening slot 2 includes: a rectangular opening slot 4 drawn on the left side of the dielectric substrate 1, one end of which is connected to the starting point of the exponential gradient line, and the other end connected to a circular slot 5. The rectangular opening slot 4 couples electromagnetic waves and confines the surface current of the patch when the Vivaldi antenna is operating. The circular slot 5 is also drawn on the left side of the dielectric substrate 1. When the Vivaldi antenna is operating, the circular slot 5 adjusts impedance matching, increases bandwidth, and improves radiation characteristics. The same exponential gradient line, rectangular slot, and circular slot 5 are drawn on the right side of the substrate, forming a symmetrical structure along the center line of the substrate. In the exponential gradient line, the longer exponential gradient curve satisfies the following formula:

[0052] y1=c1*e ax -c1+g / 2 (1);

[0053] In equation (1), c1 is the first coefficient, a is the exponential coefficient, x is the horizontal coordinate, and g is the width of the rectangular groove;

[0054] Shorter exponential gradient curves satisfy the following formula:

[0055] y2=-(c2*e ax -c2+g / 2) (2);

[0056] In equation (2), c2 is the second coefficient, a is the exponential coefficient, x is the horizontal coordinate, and g is the width of the rectangular groove;

[0057] In equation (1), c1 satisfies the following formula:

[0058] c1=((wa-g) / 2) / (e a*lb -1)(3);

[0059] In equation (3), wa is the center distance between the two circular grooves 5, and lb is the length of the long exponential groove line;

[0060] In equation (2), c2 satisfies the following formula:

[0061] c2=((wa-g) / 2) / (e a*la -1) (4);

[0062] In equation (4), la is the length of the short exponential groove;

[0063] After simulation optimization using formulas (1) to (4), the better values ​​are selected, and the specific results are as follows: the lengths of the long and short exponential grooves are lb = 100 mm and la = 50 mm, respectively; the rectangular groove lg = 5 mm; the distance from the end of the rectangular groove to the end of the substrate is l1 = 25 mm; the radius rs of the circular groove 5 is 4.8-5.2 mm, preferably rs = 5 mm; the center distance between the two circular grooves 5 is wa = 42 mm; and the width g of the rectangular groove is 0.55-0.65 mm, preferably g = 0.6 mm.

[0064] Multiple elliptical slots 6 are formed on the radiating patch and symmetrically arranged on both sides of the gradient slot 2. Each elliptical slot 6 is part of an entire ellipse. The centers of multiple elliptical slots 6 on the same side are arranged in a gradually changing direction along the center line of the gradient slot 2. The major axis of each elliptical slot 6 forms an angle with the center line of the gradient slot 2. The center of the first elliptical slot 6 is ca = 18 mm from the starting point of the exponential slot line and cb = 39 mm from the center line of the dielectric substrate 1. The minor axis ta of the elliptical slot 6 is 2.9 to 3.1 mm, preferably ta = 3 mm, and the major axis tb = 12 mm.

[0065] The microstrip feeding structure 3 is disposed on the lower surface of the dielectric substrate 1.

[0066] The ultra-wideband dual-slot Vivaldi antenna for air-coupled radar proposed in this embodiment has multiple elliptical slots 6 formed on the radiating patch and symmetrically arranged on both sides of the gradient slot 2. Each elliptical slot 6 is part of an entire ellipse, and the centers of the multiple elliptical slots 6 on the same side are arranged in a gradually changing direction along the center line of the gradient slot 2. The major axis of the elliptical slot 6 makes an angle with the center line of the gradient slot 2, which improves the surface current distribution of the antenna, suppresses the current backflow phenomenon, reduces sidelobe energy, concentrates energy in the main radiation direction, and greatly improves the antenna gain and directivity.

[0067] In some embodiments, the centers of multiple elliptical slots 6 on the same side are arranged at intervals of a first distance along the x-direction and a second distance along the y-direction. The x-direction is parallel to the centerline of the gradient slot 2, and the y-direction is perpendicular to the x-direction. The center of adjacent elliptical slots 6 is spaced qa 12-14 mm along the x-direction and qb 1.5-2.5 mm along the y-direction. This increases the antenna gain while keeping the antenna operating bandwidth essentially unchanged, avoiding a reduction in the low-frequency bandwidth of the antenna and improving the reliability of the device. To improve the gain of the elliptical slots 5 without affecting the antenna bandwidth, the parameters qa and qb are optimized through simulation. The optimization results are as follows: Figure 4 As shown, the preferred values ​​are qa = 13 mm and qb = 2 mm.

[0068] In some embodiments, the angle between the major axis of the elliptical slot 6 and the y-direction is 25 to 29 degrees. This angle further improves the antenna's gain and directivity, resulting in better antenna gain. A preferred angle is 27 degrees, which provides the optimal gain.

[0069] In some embodiments, the major axes and minor axes of each of the elliptical slots 6 are equal. The elliptical slots 6 of this embodiment can improve antenna gain in the S, C, and X bands, expand bandwidth, and improve antenna gain at low frequencies without decreasing gain at high frequencies.

[0070] Simulation results of S11 and gain for the original Vivaldi antenna and the antenna of Example 1 are as follows: Figure 5 and Figure 6 As shown, after cutting multiple pairs of gradually tilted elliptical slots 6, the antenna's operating bandwidth changes from 1.4-12GHz to 1.3-12GHz, meaning the operating frequency band remains essentially unchanged. However, the antenna gain is significantly improved in the 2.5-12GHz range, with a maximum increase of 1.5dBi. This is because the cut elliptical slots 5 improve the surface current distribution of the antenna, suppress current backflow, and allow more energy to be radiated from the main radiation direction. Figure 14 Figures 15 and 16 show the simulated XOY plane radiation patterns of the antenna at 4.5, 6.5, and 8 GHz, respectively. It can be clearly seen that the side lobes of the antenna become smaller, which means that the energy at the main lobe increases, and the main lobe width becomes narrower, which means that the antenna directivity is improved and the gain is significantly improved.

[0071] Example 2

[0072] The difference between this embodiment and embodiment 1 is that a gain unit 7 is added based on embodiment 1.

[0073] In some embodiments, the ultra-wideband dual-slot Vivaldi antenna further includes multiple gain units 7, which are disposed on the upper surface of the dielectric substrate 1 and located in the region where the gradient slot 2 is located. The gain units 7 are made of subwavelength metamaterials. In this embodiment, the metamaterial used is an LC-type electromagnetic metamaterial, which resonates and couples the transmitted electromagnetic waves. The coupling between the gain units 7 and the transmitted electromagnetic waves increases the antenna gain within the 3.5-10.5 GHz bandwidth, improving the antenna's radiation performance in the mid-frequency band.

[0074] In some embodiments, the gain unit 7 includes a plurality of first rectangular blocks with gradually varying lengths and a second rectangular block. The centers of the plurality of first rectangular blocks are arranged in a straight line parallel to the center line of the gradually changing opening slot 2. The second rectangular block is located between the two middle first rectangular blocks, and the length direction of the second rectangular block is perpendicular to the center line of the gradually changing opening slot 2. Its specific dimensions are as follows: x1 = 4mm, x2 = 3mm, x3 = 1.75–1.85mm, y1 = 4mm, y2 = 0.75–0.85mm, y3 = 0.65–0.75mm, y4 = 0.18–0.22mm. The S-parameter simulation results of this gain unit 7 are as follows: Figure 10 As shown in (a), S11 is less than -20dB in the 1-15GHz frequency band, and S21 is close to 0, which indicates that most electromagnetic waves can pass through the metamaterial structure. Figure 10 (b) represents the equivalent dielectric parameters of the gain unit 7. Its equivalent dielectric constant ε, magnetic permeability μ, and effective refractive index n are between 1 and 1.3, which are slightly larger than the equivalent dielectric parameters of air. According to the equivalent medium theory, the metamaterial structure can be equivalent to an artificial lens.

[0075] from Figure 5 and Figure 6 As observed, after adding gain unit 7, the antenna's operating frequency band remained essentially unchanged, while the gain increased in the mid-band of 3.5–10.5 GHz, with a maximum increase of 0.93 dBi. This is because electromagnetic waves resonate with the metamaterial structure, increasing the antenna's coupling and thus improving the gain. Figure 14 This can be confirmed by 15 and 16.

[0076] Based on the optimized parameters obtained from simulation, the Vivaldi antenna provided in Example 3 was designed, fabricated, and tested. A physical image is shown below. Figure 11 As shown. The S11 obtained from the test is as follows. Figure 12 As shown, the gain obtained from the test is as follows: Figure 13 As shown, the trend of the physical S11 curve is consistent with the simulation, with some errors in some low and high frequency bands. The antenna gain is slightly lower than the simulation in the mid-frequency band and lower than the simulation in the high-frequency band. This is due to the manufacturing error of the 3D printed physical antenna and the test environment. The test environment has poor working conditions and high loss in the high-frequency band.

[0077] Example 3

[0078] The difference between this embodiment and embodiment 2 is that, based on embodiment 2, a specific structure of the microstrip feeding structure 3 is designed.

[0079] The microstrip power supply structure 3 employs a T-type power divider. The microstrip power supply structure 3 includes a first microstrip line, a second microstrip line, a third microstrip line, a fourth microstrip line, and a fan-shaped stub connected sequentially. The end of the first microstrip line is connected to two second microstrip lines. Both the second and fourth microstrip lines are perpendicular to the first microstrip line, while the third microstrip line is parallel to the first microstrip line. The fan-shaped stub is located at the end of the fourth microstrip line. The width w1 of the first microstrip line is 2.1–2.3 mm, preferably w1 = 2.2 mm, and the length l2 is 12.4–12.8 mm, preferably l2 = 12.6 mm. The width w2 of the second microstrip line is 0.55–0.65 mm, preferably w2 = 0.6 mm, and the length l4 = 20 mm. The length l5 of the third microstrip line is 13 mm, and its width is the same as that of the second microstrip line. The length l6 of the fourth microstrip line is 10 mm, and its width is the same as that of the second microstrip line.

[0080] In a further embodiment, a V-shaped chamfer is provided at the junction of the end of the first microstrip line and the two second microstrip lines. The V-shaped chamfer can improve the impedance matching of the antenna and lower the low-frequency operating point without changing the antenna size, thereby meeting the miniaturization requirements of air-coupled radar. The length l3 of the V-shaped chamfer along the length direction of the first microstrip line determines the size of the low-frequency operating point to be between 1 and 2 mm, and after optimization analysis, l3 is 1.6 mm.

[0081] In some embodiments, the arc degree of the fan-shaped branch is 105-115 degrees, and its radius rp is 5.2-5.8 mm, preferably rp = 5.5 mm. The T-type power divider is used to receive the transmitted electromagnetic waves and transmit them to the radiating patch for radiation through the dielectric substrate 1, which affects the impedance matching of the antenna. By setting the above parameters, the impedance matching of the antenna is better, the return loss is lower, the radiation efficiency is better, and the performance of the antenna is improved. The arc degree is preferably 110 degrees.

[0082] In some embodiments, the dielectric substrate 1 is made of Rogers RT5880, with a dielectric constant of 2.2 and a thickness of 0.75–0.8 mm. Rogers RT5880 is a polytetrafluoroethylene (PTFE) glass fiber reinforced material. These microfibers are randomly distributed within the material, providing maximum strength reinforcement for circuit applications and circuit manufacturing processes. This material has the lowest dielectric constant among similar materials, and its extremely low dielectric loss makes it ideal for high-frequency, wide-band applications requiring minimal dispersion and loss. It is easily cut into the required shapes and resists the erosion of all solutions and reagents used in etching and through-hole plating processes. RT5880 laminates feature the lowest dielectric loss among reinforced PTFE materials, low moisture absorption, isotropy, and minimal change in electrical properties with frequency.

[0083] The working principle of the ultra-wideband dual-slot Vivaldi antenna for air-coupled radar in this embodiment is as follows: multiple elliptical slots 6 are formed on the radiating patch and symmetrically arranged on both sides of the gradient slot 2. Each elliptical slot 6 is part of an entire ellipse. The centers of multiple elliptical slots 6 on the same side are arranged in a gradually changing direction along the center line of the gradient slot 2. The major axis of the elliptical slot 6 makes an angle with the center line of the gradient slot 2, which improves the surface current distribution of the antenna, suppresses the current backflow phenomenon, reduces sidelobe energy, concentrates energy in the main radiation direction, and greatly improves the antenna gain and directivity.

[0084] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An ultra-wideband dual-slot Vivaldi antenna for air-coupled radar, characterized in that, It includes a dielectric substrate, a gradient slot, an elliptical slot, a microstrip feed structure, and multiple gain units, wherein: A radiation patch is attached to the upper surface of the dielectric substrate; The gradient opening groove is formed on the radiating patch and has a trumpet-shaped opening. Multiple elliptical opening slots are formed on the radiating patch and symmetrically arranged on both sides of the gradient opening slot. Each elliptical opening slot is part of the entire ellipse. The centers of multiple elliptical opening slots on the same side are arranged in a gradually changing direction along the center line of the gradient opening slot. The major axis of the elliptical opening slot has an angle with the center line of the gradient opening slot. The microstrip feeding structure is disposed on the lower surface of the dielectric substrate; The gain unit is disposed on the upper surface of the dielectric substrate and located in the region where the gradient opening groove is located. The gain unit is made of a subwavelength metamaterial. The gain unit includes a plurality of first rectangular blocks with varying lengths and a second rectangular block. The centers of the plurality of first rectangular blocks are arranged in a straight line along a direction parallel to the center line of the gradient opening groove. The second rectangular block is located between the two middle first rectangular blocks, and the length direction of the second rectangular block is perpendicular to the center line of the gradient opening groove.

2. The ultra-wideband dual-slot Vivaldi antenna for air-coupled radar as described in claim 1, characterized in that, The centers of multiple elliptical opening slots on the same side are arranged at intervals of a first distance along the x-direction and a second distance along the y-direction, with the x-direction parallel to the centerline of the gradient opening slot and the y-direction perpendicular to the x-direction.

3. The ultra-wideband dual-slot Vivaldi antenna for air-coupled radar as described in claim 2, characterized in that, The angle between the major axis of the elliptical opening groove and the y-direction is 25 to 29 degrees.

4. The ultra-wideband dual-slot Vivaldi antenna for air-coupled radar as described in claim 1, characterized in that, The major axis and minor axis of each of the elliptical opening slots are equal.

5. The ultra-wideband dual-slot Vivaldi antenna for air-coupled radar as described in claim 1, characterized in that, The microstrip power supply structure adopts a T-type power divider. The microstrip power supply structure includes a first microstrip line, a second microstrip line, a third microstrip line, a fourth microstrip line, and a fan-shaped stub connected in sequence. The end of the first microstrip line is connected to two second microstrip lines. The second and fourth microstrip lines are perpendicular to the first microstrip line. The third microstrip line is parallel to the first microstrip line. The fan-shaped stub is located at the end of the fourth microstrip line.

6. The ultra-wideband dual-slot Vivaldi antenna for air-coupled radar as described in claim 5, characterized in that, The end of the first microstrip line is provided with a V-shaped chamfer at the connection point between it and the two second microstrip lines.

7. The ultra-wideband dual-slot Vivaldi antenna for air-coupled radar as described in claim 6, characterized in that, The arc of the fan-shaped branch has a degree of 105 to 115 degrees.

8. The ultra-wideband dual-slot Vivaldi antenna for air-coupled radar as described in any one of claims 1-7, characterized in that, The dielectric substrate is made of Rogers RT5880, with a dielectric constant of 2.2 and a thickness of 0.75–0.8 mm.

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