Broadband tight coupling Vivaldi array antenna

Abstract

A broadband tight-coupling Vivaldi array antenna comprises N + 2 antenna sub-arrays arranged along an H plane, each antenna sub-array is formed by tightly arranging a plurality of tight-coupling Vivaldi antenna units along an E plane, each tight-coupling Vivaldi antenna unit comprises a dielectric substrate, a radiation patch and a metamaterial patch are printed on the upper surface of the dielectric substrate, a feed balun is printed on the lower surface of the dielectric substrate, and the feed balun is arranged on the upper surface of the dielectric substrate. A radio frequency coaxial connector is arranged at the bottom of the dielectric substrate, a needle-shaped inner conductor end of the radio frequency coaxial connector is connected with the feed balun, and a cylindrical outer conductor end of the radio frequency coaxial connector is in contact with the radiation patch; according to the invention, the miniaturization of the Vivaldi antenna array is realized by utilizing the coupling effect between the units, the edge current path is prolonged by introducing the edge piece and the dummy element at the edge of the array, the active standing-wave ratio of the Vivaldi antenna array during angle scanning is improved to a certain extent, and 60-degree beam scanning is realized on the E surface and the H surface; moreover, the antenna is simple in structure, simplifies the design process of the antenna, and is lower in machining difficulty and cost.

Description

Technical Field

[0001] The present invention belongs to the field of radar communication technology, and further relates to the field of tightly coupled antenna technology in the field of antenna technology, and specifically to a miniaturized broadband tightly coupled Vivaldi array antenna. Background Art

[0002] With the rapid development of wireless communication technology, wireless communication equipment is increasingly used in military and civilian fields. In order to meet the functional requirements of high-speed, large-capacity data transmission, multi-channel communication, multi-system collaborative high-precision positioning, etc., the performance of antennas, as a key component of wireless communication systems, is particularly important.

[0003] In modern wireless communication systems and radar systems, broadband and wide-angle array antennas are widely used. The radiation direction is controlled by adjusting the phase of the unit to achieve beam scanning. Traditional antenna array designs often try to eliminate the coupling between arrays to avoid the influence of mutual coupling effects on the overall performance of the array. The method usually used is to increase the unit spacing. However, in today's complex electromagnetic signal environment, the integration requirements of wireless communication systems are getting higher and higher, and the space left for antennas is getting more and more limited. It is necessary to use miniaturized broadband and wide-angle scanning array antennas.

[0004] Therefore, the concept of tight coupling was proposed and developed rapidly. The basic principle of tightly coupled antenna is to use the mutual coupling effect between adjacent array elements to form a continuous current distribution, expand the bandwidth of the antenna and enhance the radiation performance and beam scanning capability of the antenna. Tight coupling design helps to reduce the array element spacing and unit size, can achieve miniaturization, easy integration, and has broad application prospects in wireless communications, radar detection, satellite navigation and other fields.

[0005] In 2024, Xi'an Jiaotong University disclosed an integrated tightly coupled antenna in the patent document "Tightly coupled antenna with integrated processing parameter differences" (application number 202410582507.6, application publication number CN 118539146A). The antenna includes a dielectric substrate, an antenna body, a feed balun, a reflector and an RF connector. The relative positions of the antenna patches are configured on a multi-layer PCB board to avoid the influence of mutual interference, but the bandwidth with a reflection coefficient less than or equal to 10dB is relatively narrow.

[0006] In 2024, a high-performance tightly coupled array antenna with a compact feeding network was disclosed in patent application CN118117347A, which includes a bowtie dipole, parallel metal strips, a dielectric board with a printed antenna radiation structure, a double Y balun, a metal sheet with introduced coupling, a third-order Chebyshev impedance transformer, a dielectric board with a printed feeding network and a floor structure, a coaxial port, a floor, and a grounding metal wire. By cascading the Chebyshev third-order impedance transformer and the double Y balun with a gradually changing output width, impedance transformation within a wide band and unbalanced feeding to balanced feeding are achieved, and the introduction of parasitic metal strips realizes the improvement of active standing waves at large scanning angles. However, this is the result under wireless periodic array conditions, and the reflection coefficient under finite array conditions is not given. Summary of the invention

[0007] In order to solve the deficiencies in the above-mentioned prior art, the purpose of the present invention is to provide a broadband tightly coupled Vivaldi array antenna, which utilizes the coupling effect between units to achieve a good standing wave ratio in a wider bandwidth at a smaller size, thereby realizing a miniaturized design of the antenna and enabling wide-angle scanning; it solves the matching deterioration caused by the truncation effect of a finite-size tightly coupled antenna array, and realizes a tightly coupled Vivaldi array antenna with wide bandwidth and angle scanning, which has the advantages of simple structure and low profile.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] A broadband tightly coupled Vivaldi array antenna comprises N+2 antenna subarrays arranged along an H plane; each antenna subarray is composed of a plurality of tightly coupled Vivaldi antenna units tightly arranged along an E plane, the tightly coupled Vivaldi antenna unit comprises a dielectric substrate 3, a radiation patch 1 and a metamaterial patch 4 are printed on the upper surface of the dielectric substrate 3, a feed balun 2 is printed on the lower surface of the dielectric substrate 3, a radio frequency coaxial connector 5 is provided at the bottom of the dielectric substrate 3, a needle-shaped inner conductor end of the radio frequency coaxial connector 5 is connected to the feed balun 2, and a cylindrical outer conductor end of the radio frequency coaxial connector 5 is in contact with the radiation patch 1.

[0010] The N+2 antenna sub-arrays are arranged along the H plane, and N is an integer greater than or equal to 4.

[0011] Edge pieces 6 are added to the edges of both sides of each antenna subarray, and a plurality of elliptical grooves 61 are evenly provided on the edges of the edge pieces 6, and the elliptical grooves on both sides are symmetrically arranged.

[0012] In each antenna subarray, there are no less than 4 tightly coupled Vivaldi antenna units closely arranged along the E-plane.

[0013] An open slot 14 is provided in the middle of the radiation patch 1 printed on the upper surface of the dielectric substrate 3. The open slot 14 is surrounded by the first gradient slot line 11, the second gradient slot line 12 and the circular slot line 13 to form an axisymmetric horn shape. The circular slot line 13 plays a matching impedance role for the feeding balun 2.

[0014] A rectangular coordinate system is established with the left bottom corner of the upper surface of the dielectric substrate 3 as the origin, and the function equation satisfied by the second gradient groove line 12 is:

[0015] x=c1*e py +c2

[0016]

[0017] Wherein, (x1, y1), (x2, y2) are the coordinates of the starting point and the ending point of the first gradient groove line 11, p=0.7 is the curvature of the curve, and c1 and c2 are two constants that satisfy the equation.

[0018] The metamaterial patch 4 is composed of a plurality of rectangular open rings 41 , and the middle of the four sides of the rectangular open rings 41 are all provided with openings.

[0019] The rectangular open rings 41 are arranged at equal intervals layer by layer with the center line of the antenna unit as the symmetry axis, and each layer has two fewer rectangular open rings 41 than the previous layer, until the last layer has one rectangular open ring 41, forming an inverted isosceles triangle-shaped metamaterial patch 4.

[0020] The feeding balun 2 is formed by connecting the first microstrip line 21, the gradient microstrip line 22, the second microstrip line 23, and the fan-shaped matching branch 24 in sequence. The first microstrip line 21 is connected to the top of the RF coaxial connector 5. The gradient microstrip line 22 plays an impedance transformation role to make the impedance of the microstrip line 21 and the first gradient slot line 11 matched. The fan-shaped matching branch 24 can balance the unbalanced feeding between the first microstrip line 21 and the second gradient slot line 12.

[0021] The dielectric substrate 3 is made of Rogers RT / duroid 5880 dielectric plate.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] 1. The present invention utilizes tight coupling technology, and weakens the influence of truncation effect by extending the edge radiation arm and loading dummy elements. By loading the metamaterial structure, the antenna unit has a better impedance matching effect, further widening the bandwidth. Compared with the traditional Vivaldi antenna, it can achieve good impedance matching characteristics within a wider bandwidth at a smaller size, and ensures the high performance of the antenna while achieving miniaturization. The antenna structure is simple, does not require multi-layer PCB boards and other complex structures, is low in cost, and is easy to process.

[0024] 2. The size of the radiation patch of the traditional Vivaldi antenna is related to the low-frequency wavelength, and its size is generally large. Grating lobes will appear when the array is formed for wide-angle beam scanning. The size of the radiation patch of the antenna of the present invention is half of the high-frequency working wavelength, which meets the condition that no grating lobes will appear when the 60° internal beam scanning is performed at each frequency point, and the radiation characteristics are good.

[0025] In summary, the broadband tightly coupled Vivaldi antenna of the present invention utilizes the coupling effect between units to achieve a good standing wave ratio in a wider bandwidth at a smaller size, realizes the miniaturized design of the antenna, and can achieve wide-angle scanning, so that the antenna of the present invention has the advantages of simple structure and low profile. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of a broadband tightly coupled Vivaldi array antenna according to an embodiment of the present invention.

[0027] Figure 2 Schematic diagram of a broadband tightly coupled Vivaldi array antenna subarray according to an embodiment of the present invention.

[0028] Figure 3 Schematic diagram of the tightly coupled Vivaldi antenna unit of the present invention; wherein, Figure 3 (a) is a schematic diagram of the overall structure of the antenna unit; Figure 3 (b) is a schematic side view of the antenna unit;

[0029] Figure 3 (c) is a horizontal schematic diagram of the upper surface of the dielectric substrate of the antenna unit; Figure 3 (d) is a horizontal schematic diagram of the upper surface of the antenna unit dielectric substrate.

[0030] Figure 4 is the E-plane and H-plane radiation pattern of the tightly coupled Vivaldi antenna unit under infinite periodic boundary conditions, where: Figure 4 (a) is the E-plane and H-plane radiation pattern of the unit at 4.5GHz. Figure 4 (b) is the E-plane and H-plane radiation pattern of the unit at 10GHz. Figure 4 (c) is the E-plane and H-plane radiation pattern of the unit at 15GHz. Figure 4 (d) is the E-plane and H-plane radiation pattern of the unit at 24.5GHz.

[0031] Figure 5 is the standing wave ratio of the tightly coupled Vivaldi antenna unit under infinite periodic boundary conditions.

[0032] Figure 6 is the E-plane scanning pattern of the broadband tightly coupled Vivaldi array antenna at different frequencies and scanning angles, where: Figure 6 (a) is the E-plane scanning pattern of the antenna array at 4.5GHz when the scanning angle is 0, 30, 45, and 60 degrees. Figure 6 (b) is the E-plane scanning pattern of the antenna array at 10 GHz when the scanning angle is 0, 30, 45, and 60 degrees. Figure 6 (c) is the E-plane scanning pattern of the antenna array at 15GHz when the scanning angle is 0, 30, 45, and 60 degrees. Figure 6 (d) is the E-plane scanning pattern of the antenna array at 24.5GHz when the scanning angles are 0 degrees, 30 degrees, 45 degrees, and 60 degrees.

[0033] Figure 7 is the active standing wave ratio of the broadband tightly coupled Vivaldi array antenna at each scanning angle on the E plane.

[0034] Figure 8 is the H-plane scanning pattern of the broadband tightly coupled Vivaldi array antenna at different frequencies and scanning angles, where: Figure 8 (a) is the H-plane scanning pattern of the antenna array at 4.5GHz when the scanning angle is 0, 30, 45, and 60 degrees. Figure 8 (b) is the H-plane scanning pattern of the antenna array at 10GHz when the scanning angle is 0, 30, 45, and 60 degrees. Figure 8 (c) is the H-plane scanning pattern of the antenna array at 15GHz when the scanning angles are 0, 30, 45, and 60 degrees. Figure 8 (d) is the H-plane scanning pattern of the antenna array at 24.5GHz when the scanning angles are 0 degrees, 30 degrees, 45 degrees, and 60 degrees.

[0035] Fig. 9 is the active standing wave ratio of the broadband tightly coupled Vivaldi array antenna at each scanning angle in the H plane. DETAILED DESCRIPTION

[0036] The embodiments and effects of the present invention are further described below in conjunction with the accompanying drawings.

[0037] The antenna of the present invention is a broadband tightly coupled Vivaldi array antenna operating at 4.5 GHz to 24.5 GHz, and the number N of the array antenna radiating units is determined by the actual use of the antenna. The broadband tightly coupled Vivaldi array antenna of the embodiment of the present invention uses 8×8 broadband tightly coupled Vivaldi antenna radiating units, but those skilled in the art should understand that the broadband tightly coupled Vivaldi array antenna can also be composed of other numbers of broadband tightly coupled Vivaldi antenna units. For example, 4×4, 6×6, 8×8... The embodiment of the present invention does not limit this.

[0038] Reference Figure 1 , the broadband tightly coupled Vivaldi array antenna structure of an embodiment of the present invention is further described.

[0039] The broadband tightly coupled Vivaldi array antenna of the embodiment of the present invention adopts 64 broadband tightly coupled Vivaldi antenna units, with 1×10 broadband tightly coupled Vivaldi array antenna subarrays, according to Figure 1 The pattern shown is arranged in an equidistant manner along the H-plane direction of the antenna unit. The two edge broadband tightly coupled Vivaldi array antenna subarrays are not fed and are connected to a matching load to form a 64-element broadband tightly coupled Vivaldi array antenna.

[0040] Reference Figure 2 , a sub-array structure of the broadband tightly coupled Vivaldi array antenna according to an embodiment of the present invention is further described.

[0041] Each antenna subarray is composed of 8 broadband tightly coupled Vivaldi antenna units arranged closely. Edge pieces 6 of the same length and width as the broadband tightly coupled Vivaldi antenna units are added to the edges of both sides of each antenna subarray. The edge pieces 6 are obtained by opening evenly arranged elliptical grooves 61 on the edges of rectangular patches. The edge pieces 6 and the elliptical grooves extend the radiation arms of the edge units, extend the current path of the edge units, and improve the impedance matching of the antenna.

[0042] Reference Figure 3 , the structure of the broadband tightly coupled Vivaldi antenna unit of an embodiment of the present invention is further described.

[0043] The broadband tightly coupled Vivaldi antenna unit comprises a dielectric substrate 3, a radiation patch 1, a feed balun 2, a metamaterial patch 4 and a radio frequency coaxial connector 5. The radiation patch 1 and the metamaterial patch 4 are printed on the upper surface of the dielectric substrate 3, and the feed balun 2 is printed on the lower surface of the dielectric substrate. The needle-shaped inner conductor end of the radio frequency coaxial connector 5 is connected to the feed balun 2, and the cylindrical outer conductor end of the radio frequency coaxial connector 5 is in contact with the radiation patch 1.

[0044] The dielectric substrate 3 is made of Rogers RT / duroid 5880 dielectric plate with a thickness of 0.508 mm and a width of 0.49 times the wavelength corresponding to the highest operating frequency.

[0045] The open slot in the radiation patch 1 is surrounded by a first tapered slot line 11, a second tapered slot line 12 and a circular slot line 13. The tapered slot line radiates electromagnetic waves, and the circular slot line 13 plays a matching impedance role for the microstrip transmission line. The feeding balun 2 adopts coupling feeding, and couples out a current at the beginning of the tapered slot line 11. The current propagates along the open slot to radiate the electromagnetic wave. The metamaterial patch 4 is printed at the open slot. The metamaterial patch 4 is composed of a plurality of rectangular open rings 41. The rectangular open rings 41 are arranged at equal intervals with the center line of the open slot as the symmetry axis. The metamaterial patch can improve the impedance matching of the Vivaldi antenna. The radiation patch 1 has a length of l0=18mm and a width of w0=6mm. The lengths of the tapered slot lines 11 and 12 are l1=10.4mm, the radius of the circular slot line 13 is r0=1.2mm, the inner length of the rectangular open ring 41 is l2=0.16mm, and the outer length is l3=0.2mm. A rectangular coordinate system is established with the lower left edge of the dielectric substrate as the origin, and the function equation satisfied by the gradient groove line 11 is:

[0046] x=c1*e py +c2

[0047]

[0048] Wherein, (x1, y1), (x2, y2) are the coordinates of the starting point and the ending point of the gradient groove line 11, p=0.7 is the curvature of the curve, and c1 and c2 are two constants that satisfy the equation.

[0049] The feeding balun 2 is formed by connecting a first microstrip line 21, a gradient microstrip line 22, a second microstrip line 23, and a fan-shaped matching branch 24. The gradient microstrip line 22 plays an impedance transformation role to make the impedance of the first microstrip line 21 and the gradient slot line 11 matched. The fan-shaped matching branch 24 can balance the unbalanced feeding between the first microstrip line 21 and the second gradient slot line 12. The width of the first microstrip line 21 is w1=1.44mm, the length of the gradient microstrip line 22 is l4=6.34mm, the width of the second microstrip line 23 is w2=0.4mm, the radius of the fan-shaped matching branch 24 is r1=2.6mm, the thickness of the dielectric substrate 3 is h=0.508mm, the major axis of the elliptical opening slot is r3=2mm, and the minor axis is r2=1mm.

[0050] The effect of the present invention is further described below in conjunction with simulation experiments.

[0051] 1. Simulation experiment conditions

[0052] The simulation experiment of the present invention uses the Ansys Electronics Desktop software platform installed on computer hardware to complete the simulation of the Ka-band dual circular polarization phased array antenna.

[0053] 2. Simulation content and result analysis

[0054] The simulation experiment of the present invention is to simulate the unit and 8×8 array of the broadband tightly coupled Vivaldi antenna of the embodiment of the present invention in the range of 4.5GHz to 24.5GHz. The simulation results are plotted into curve graphs, such as Figure 4 , Figure 5 , Figure 6 , Figure 7 , Figure 8 , Fig. 9 As shown. Among them, Figure 4 are the E-plane and H-plane radiation patterns of the broadband tightly coupled Vivaldi antenna unit under infinite periodic boundary conditions, Figure 5 is the standing wave ratio of the tightly coupled Vivaldi antenna unit under infinite periodic boundary conditions; Figure 6 is the E-plane scanning pattern of the broadband tightly coupled Vivaldi array antenna at different frequencies and scanning angles, Figure 7 is the active standing wave ratio of the broadband tightly coupled Vivaldi array antenna at different scanning angles on the E plane, Figure 8 is the H-plane scanning pattern of the broadband tightly coupled Vivaldi array antenna at different frequencies and scanning angles, Fig. 9 It is the active standing wave ratio of the broadband tightly coupled Vivaldi array antenna when the H-plane scanning angle is 0 degree, 30 degree, 45 degree and 60 degree.

[0055] The effects of the present invention are further described below in conjunction with simulation diagrams.

[0056] from Figure 4 , Figure 5 It can be seen that the impedance bandwidth of the antenna unit with a standing wave ratio less than 2 under infinite periodic boundary conditions is 4.5 GHz to 24.5 GHz, and the E-plane and H-plane radiation performance of the antenna unit at 4.5 GHz, 10 GHz, 15 GHz, and 24.5 GHz are good.

[0057] from Figure 6 It can be seen that the broadband tightly coupled Vivaldi array antenna can achieve 60-degree beam scanning on the E-plane at four frequencies of 4.5 GHz, 10 GHz, 15 GHz, and 24.5 GHz.

[0058] from Figure 7 It can be seen that the active standing wave ratio of the array antenna at different scanning angles on the E plane is less than 3, which meets the source standing wave ratio requirements of the tightly coupled phased array antenna.

[0059] from Figure 8 It can be seen that the broadband tightly coupled Vivaldi array antenna can achieve 60-degree beam scanning on the H-plane at four frequencies of 4.5 GHz, 10 GHz, 15 GHz, and 24.5 GHz.

[0060] from Fig. 9 It can be seen that the active standing wave ratio of the array antenna at different scanning angles on the H plane is less than 3, which meets the requirements of the active standing wave ratio of the tightly coupled phased array antenna.

[0061] The above simulation experiments show that compared with the prior art, the present invention utilizes the coupling effect between units to achieve miniaturization of antenna units, has good radiation characteristics in the entire wide frequency band, and the array antenna can achieve 60-degree beam scanning on the E and H planes.

[0062] The specific embodiments of the present invention do not constitute any limitation to the present invention. Obviously, for professionals in this field, after understanding the content and principles of the present invention, they may make various modifications and changes in form and details without departing from the principles and structures of the present invention. However, these modifications and changes based on the ideas of the present invention are still within the scope of protection of the claims of the present invention.

Claims

1. A broadband tightly coupled Vivaldi array antenna, comprising N+2 antenna subarrays arranged along an H plane; characterized in that: Each antenna subarray is composed of a plurality of tightly coupled Vivaldi antenna units tightly arranged along the E-plane, wherein the tightly coupled Vivaldi antenna unit comprises a dielectric substrate (3), wherein the upper surface of the dielectric substrate (3) is printed with a radiation patch (1) and a metamaterial patch (4), and the lower surface of the dielectric substrate (3) is printed with a feed balun (2), and a radio frequency coaxial connector (5) is provided at the bottom of the dielectric substrate (3), wherein the needle-shaped inner conductor end of the radio frequency coaxial connector (5) is connected to the feed balun (2), and the cylindrical outer conductor end of the radio frequency coaxial connector (5) is in contact with the radiation patch (1).

2. A broadband tightly coupled Vivaldi array antenna according to claim 1, characterized in that: The N+2 antenna sub-arrays are arranged along the H plane, and N is an integer greater than or equal to 4.

3. A broadband tightly coupled Vivaldi array antenna according to claim 1 or 2, characterized in that: Edge pieces (6) are added to the edges of both sides of each antenna subarray, and a plurality of elliptical grooves (61) are evenly provided on the edges of the edge pieces (6), and the elliptical grooves on both sides are symmetrically arranged.

4. The broadband tightly coupled Vivaldi array antenna according to claim 1, characterized in that: In each antenna subarray, there are no less than 4 tightly coupled Vivaldi antenna units closely arranged along the E-plane.

5. The broadband tightly coupled Vivaldi array antenna according to claim 1, characterized in that: An open slot (14) is provided in the middle of the radiation patch (1) printed on the upper surface of the dielectric substrate (3); the open slot (14) is surrounded by a first gradient slot line (11), a second gradient slot line (12) and a circular slot line (13) to form an axisymmetric horn shape; the circular slot line (13) plays a matching impedance role for the feeding balun (2).

6. The broadband tightly coupled Vivaldi array antenna according to claim 5, characterized in that: A rectangular coordinate system is established with the left bottom corner of the upper surface of the dielectric substrate (3) as the origin, and the function equation satisfied by the second gradient groove line (12) is: x=c1*e py +c2; Wherein, (x1, y1), (x2, y2) are the coordinates of the starting point and the ending point of the first gradient groove line (11), p=0.7 is the curvature of the curve, and c1 and c2 are two constants satisfying the equation.

7. The broadband tightly coupled Vivaldi array antenna according to claim 1, characterized in that: The metamaterial patch (4) is composed of a plurality of rectangular open rings (41), and openings are arranged in the middle of the four sides of the rectangular open rings (41).

8. The broadband tightly coupled Vivaldi array antenna according to claim 7, characterized in that: The rectangular open rings (41) are arranged layer by layer at equal intervals with the center line of the antenna unit as the symmetry axis, and each layer has two fewer rectangular open rings (41) than the previous layer, until the last layer has one rectangular open ring (41), forming a metamaterial patch (4) in the shape of an inverted isosceles triangle.

9. The broadband tightly coupled Vivaldi array antenna according to claim 1, characterized in that: The feeding balun (2) is formed by sequentially connecting a first microstrip line (21), a gradient microstrip line (22), a second microstrip line (23), and a fan-shaped matching branch (24); the first microstrip line (21) is connected to the top of a radio frequency coaxial connector (5); the gradient microstrip line (22) plays an impedance transformation role so that the impedance of the microstrip line (21) and the first gradient slot line (11) are matched; and the fan-shaped matching branch (24) can balance the unbalanced feeding between the first microstrip line (21) and the second gradient slot line (12).

10. A broadband tightly coupled Vivaldi array antenna according to claim 1, 5 or 6, characterized in that: The dielectric substrate (3) is made of Rogers RT / duroid 5880 dielectric plate.

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