An Improved Vivaldi Antenna with a Slotted Structure and Loaded Directors

Abstract

An improved Vivaldi antenna with a slotted groove structure and loaded directors, belonging to the technical field of microwave antennas, solves the problem of how to design a Vivaldi antenna with high gain and miniaturization; the technical solution of the present invention is to open rectangular grooves on the tapered groove line of the horn-shaped groove of the traditional Vivaldi antenna. The rectangular grooves suppress the surface current propagating along the vertical direction, greatly reducing the side lobes of the antenna and improving the gain of the antenna; at the same time, opening the rectangular grooves ensures that without changing the size of the antenna volume, the length of the current path is effectively increased, realizing the miniaturization of the antenna; multiple annular directors with a gradually varying period of length are loaded at the opening of the horn-shaped groove. The loading direction of the annular directors is perpendicular to the opening direction and parallel to the electric field. The annular directors generate induced current, which plays a guiding role for electromagnetic waves and reduces the S-parameter of the antenna.

Description

Technical Field

[0001] The present invention belongs to the technical field of microwave antennas, and relates to an improved Vivaldi antenna with a slotted structure and a loaded director. Background Art

[0002] The emergence of advanced technologies such as 5G communication technology, automatic navigation, and artificial intelligence has led to higher demands for bandwidth, system capacity, and transmission rate. Driven by such demands, broadband antennas have received extensive attention due to their wide frequency bands and low power consumption. Among many ultra-wideband antennas, the Vivaldi antenna has advantages such as a simple planar structure, light weight, ultra-wideband impedance characteristics, easy manufacturing, high-directional radiation, and a stable radiation pattern, making it an excellent candidate antenna.

[0003] As Figure 8 shown in the structural schematic diagram of a traditional Vivaldi broadband microstrip antenna, it is composed of three layers of materials in total. The top layer is a metal ground plane, on which slot lines (shown as solid lines) are cut to form a slot structure. The slot structure consists of three parts. The first part is a circular slot, which plays an impedance matching role for the microstrip transmission line; the second part is a rectangular slot, which couples with the upper signal of the microstrip transmission line and transmits electromagnetic waves; the third part is a tapered slot line, which plays a guiding role for the electromagnetic waves radiated by the antenna. The middle layer is a dielectric board, and the bottom layer is a microstrip transmission line (shown as a dashed line). The terminal of the microstrip transmission line is a fan-shaped structure, which plays a role in terminal load matching. The microstrip transmission line couples and feeds power to the slot structure through the dielectric board.

[0004] In the prior art, the Chinese invention patent application document "A Vivaldi Antenna with a Loaded Director" with an application publication date of December 14, 2021 and an application publication number of CN113794045A can effectively improve the gain of the Vivaldi antenna by adding a director to the design of the Vivaldi antenna. The technical solution of this document uses a loaded director to improve the gain of the Vivaldi antenna, and the volume of the antenna is relatively large, which is not conducive to miniaturization design. Summary of the Invention

[0005] The technical problem to be solved by the present invention is how to design a Vivaldi antenna with high gain and miniaturization.

[0006] The present invention solves the above technical problem through the following technical solutions:

[0007] An improved Vivaldi antenna with a slotted structure and loaded directors, comprising: a metal clad copper board (1), a dielectric substrate (2), and a coupled feeding structure (3); the metal clad copper board (1) is covered on the upper surface of the dielectric substrate (2), and a circular groove (10) and a flared groove (11) are formed on the metal clad copper board (1), and the circular groove (10) is connected to the flared groove (11); the coupled feeding structure (3) is arranged on the lower surface of the dielectric substrate (2), and a plurality of identical rectangular grooves (12) are symmetrically formed along the y-axis direction on the upper and lower two tapered groove lines of the flared groove (11); a plurality of annular directors with a gradually changing period in length are loaded along the y-axis direction at the opening of the flared groove (11), and the loading direction of each annular director is perpendicular to the opening direction of the flared groove (11).

[0008] The technical solution of the present invention forms rectangular grooves on the tapered groove lines of the flared groove of the traditional Vivaldi antenna. The rectangular grooves suppress the surface current propagating along the vertical direction, greatly reduce the side lobes of the antenna, and improve the gain of the antenna; at the same time, forming the rectangular grooves ensures that the length of the current path is effectively increased without changing the size of the antenna volume, realizing the miniaturization of the antenna; a plurality of annular directors with a gradually changing period in length are loaded at the opening of the flared groove, and the loading direction of the annular directors is perpendicular to the opening direction and parallel to the electric field. The annular directors generate induced current, which plays a guiding role for electromagnetic waves and reduces the S parameter of the antenna.

[0009] Further, the rectangular groove (12) is used to increase the length of the radiation current path and suppress the surface current propagating along the y-axis direction.

[0010] Further, the spacing between the plurality of identical rectangular grooves (12) formed on the tapered groove line of the same flared groove (11) is equal.

[0011] Further, the plurality of annular directors with a gradually changing period in length are used to generate induced current and play a guiding role for electromagnetic waves.

[0012] Further, each of the plurality of annular directors with a gradually changing period in length has the same width and the length increases by a fixed length.

[0013] Further, each annular director is internally provided with an identical rectangular opening.

[0014] Further, the material of the dielectric substrate (2) is "F4B", the dielectric constant ε r = 2.6, and the loss tangent tanδ = 0.0009.

[0015] Furthermore, the coupling feed structure (3) is composed of a microstrip transmission line (31) and a fan-shaped structure (32) connected together; the microstrip transmission line (31) is used to couple-feed the circular slot (10) and the horn-shaped slot (11), and the fan-shaped structure (32) is used for load matching.

[0016] The advantages of the present invention are as follows:

[0017] The technical solution of the present invention is to open rectangular grooves on the tapered slot line of the horn-shaped slot of the traditional Vivaldi antenna. The rectangular grooves suppress the surface current propagating along the vertical direction, greatly reducing the side lobes of the antenna and improving the gain of the antenna; at the same time, opening the rectangular grooves ensures that the length of the current path is effectively increased without changing the size of the antenna volume, realizing the miniaturization of the antenna; a plurality of annular directors with gradually varying lengths arranged in a periodic manner are loaded at the opening of the horn-shaped slot. The loading direction of the annular directors is perpendicular to the opening direction and parallel to the electric field. The annular directors generate induced current, which plays a guiding role in electromagnetic waves and reduces the S-parameters of the antenna. The antenna of the present invention has a small physical size and a high gain, belongs to a broadband antenna, and is applicable to 5G communication systems. The antenna still has good matching characteristics and radiation patterns. Description of the Drawings

[0018] Figure 1 It is the front view of the improved Vivaldi antenna with a slotted structure and loaded directors according to the embodiment of the present invention;

[0019] Figure 2 It is the top view of the improved Vivaldi antenna with a slotted structure and loaded directors according to the embodiment of the present invention;

[0020] Figure 3 It is the size design diagram of the rectangular groove of the improved Vivaldi antenna with a slotted structure and loaded directors according to the embodiment of the present invention;

[0021] Figure 4 It is the size design diagram of the annular director of the improved Vivaldi antenna with a slotted structure and loaded directors according to the embodiment of the present invention;

[0022] Figure 5 It is the S 11 parameter simulation schematic diagram of the improved Vivaldi antenna with a slotted structure and loaded directors according to the embodiment of the present invention;

[0023] Figure 6 In (a) and (b), they are respectively the comparison of the radiation patterns of the traditional Vivaldi antenna and the improved Vivaldi antenna with a slotted structure and loaded directors according to the embodiment of the present invention at a working frequency of 8 GHz;

[0024] Figure 7 In (a) and (b) respectively, the contrast between the radiation patterns of the traditional Vivaldi antenna and the improved Vivaldi antenna with a slotted structure and a loaded director at a working frequency of 10 GHz according to the embodiments of the present invention;

[0025] Figure 8 It is a schematic structural diagram of a traditional Vivaldi broadband microstrip antenna. Specific embodiments

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0027] The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings of the specification and specific embodiments:

[0028] Embodiment 1

[0029] As Figure 1 and Figure 2 shown, an improved Vivaldi antenna with a slotted structure and a loaded director, including a metal-clad copper plate 1, a dielectric substrate 2, and a coupled feeding structure 3; the metal-clad copper plate 1 is covered on the upper surface of the dielectric substrate 2, and a circular groove 10 and a horn-shaped groove 11 are opened on the metal-clad copper plate 1, and the circular groove 10 is connected to the horn-shaped groove 11; the coupled feeding structure 3 is arranged on the lower surface of the dielectric substrate 2 and is composed of a microstrip transmission line 31 and a fan-shaped structure 32 connected together.

[0030] As Figure 3 and Figure 4 shown, on the upper and lower two tapered groove lines of the horn-shaped groove 11, 8 rectangular grooves 12 are symmetrically opened along the y-axis direction, for a total of 16 rectangular grooves 12; the depth H of the rectangular groove 12 is 2.5 mm, the width W of the rectangular groove 12 is 0.45 mm, the groove pitch L of the rectangular groove 12 is 0.55 mm, and the distance L from the rightmost rectangular groove 12 to the right edge of the dielectric substrate 2 ’ = 0.55 mm.

[0031] Seven annular directors are loaded along the y-axis direction at the opening between the upper and lower tapered groove lines of the horn-shaped groove 11, namely the first annular director 13, the second annular director 14, the third annular director 15, the fourth annular director 16, the fifth annular director 17, the sixth annular director 18, and the seventh annular director 19. The loading direction of each annular director is perpendicular to the opening direction of the horn-shaped groove 11; the length of each annular director increases in increments of a fixed length L” = 0.4 mm to form a tapered periodic structure; the length L1 of the first annular director 13 is 1.2 mm, the width W1 is 0.2 mm, the length L2 of the second annular director 14 is 1.6 mm, the width W2 is 0.2 mm, the length L3 of the third annular director 15 is 2.0 mm, the width W3 is 0.2 mm, the length L4 of the fourth annular director 16 is 2.4 mm, the width W4 is 0.2 mm, the length L5 of the fifth annular director 17 is 2.8 mm, the width W5 is 0.2 mm, the length L6 of the sixth annular director 18 is 3.2 mm, the width W6 is 0.2 mm, and the length L7 of the seventh annular director 19 is 3.6 mm, the width W7 is 0.2 mm; the spacing L” ’ between adjacent annular directors is 0.3 mm, and the distance L”” between the seventh annular director 19 and the right edge of the dielectric substrate 2 is 3.7855 mm; a rectangular opening is provided inside each annular director, the length L0 of the rectangular opening is 1 mm, and the width W0 of the rectangular opening is 0.1 mm.

[0032] The material of the dielectric substrate 2 is “F4B”, and the width S x of the dielectric substrate 2 is 20 mm, the length S y is 27 mm, the thickness t is 0.8 mm, the dielectric constant ε r is 2.6, and the loss tangent tanδ is 0.0009.

[0033] Design principle of the improved Vivaldi antenna of the present invention:

[0034] An improved Vivaldi antenna with a slotted structure and loaded directors according to the present invention improves the traditional Vivaldi antenna structure. A plurality of identical rectangular grooves 12 are symmetrically opened on the upper and lower tapered groove lines of the horn-shaped groove 11 of the traditional Vivaldi antenna. The rectangular grooves 12 suppress the surface current propagating along the vertical direction (y-axis direction), greatly reducing the sidelobes of the antenna and improving the gain of the antenna. At the same time, without changing the size of the antenna volume, the rectangular grooves 12 effectively increase the length of the current path, realizing the miniaturization of the antenna. Although the improved Vivaldi antenna of the present invention improves the gain of the antenna, it also increases the S-parameters of the antenna. To solve this problem, the technical solution of the present invention further loads a plurality of annular directors with a gradually varying period arrangement at the opening of the horn-shaped groove 11. In the Vivaldi antenna, the direction of the electric field is from one groove line to the other groove line and perpendicular to the opening direction. The loading direction of the annular directors of the present invention is also perpendicular to the opening direction and parallel to the electric field. Therefore, the annular directors generate induced current, which plays a guiding role for electromagnetic waves and reduces the S-parameters of the antenna.

[0035] As Figure 5 shown, the S 11 parameter curve graph of the improved Vivaldi antenna with a slotted structure and loaded directors according to the present invention. It can be seen from the figure that the value of the antenna is basically below -10 dB within the effective working frequency band, indicating that the antenna has achieved a good matching state.

[0036] As Figure 6 and Figure 7 shown, the comparison of the radiation patterns of the improved Vivaldi antenna with a slotted structure and loaded directors according to the present invention at frequencies of 8 GHz and 10 GHz. After loading the directors and slotting the traditional Vivaldi antenna, the gain of the traditional Vivaldi antenna is improved.

[0037] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0038] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. An improved Vivaldi antenna with a slotted structure and loaded directors, characterized in that Including: A metal-clad copper substrate (1), a dielectric substrate (2), and a coupled feeding structure (3); the metal-clad copper substrate (1) is covered on the upper surface of the dielectric substrate (2), a circular groove (10) and a horn-shaped groove (11) are formed on the metal-clad copper substrate (1), and the circular groove (10) is connected to the horn-shaped groove (11); the coupled feeding structure (3) is arranged on the lower surface of the dielectric substrate (2), and a plurality of identical rectangular grooves (12) are symmetrically formed along the y-axis direction on the upper and lower two tapered groove lines of the horn-shaped groove (11); a plurality of annular directors with lengths arranged in a tapered period are loaded along the y-axis direction at the opening of the horn-shaped groove (11), and the loading direction of each annular director is perpendicular to the opening direction of the horn-shaped groove (11); the rectangular grooves (12) are used to increase the length of the radiation current path and suppress the surface current propagating along the y-axis direction; the plurality of annular directors with lengths arranged in a tapered period are used to generate induced current and direct the electromagnetic wave; a same rectangular opening is formed inside each annular director.

2. The improved Vivaldi antenna with a slotted structure and a loaded director according to claim 1, characterized in that, The spacing between the plurality of identical rectangular grooves (12) formed on the tapered groove line of the same horn-shaped groove (11) is equal.

3. An improved Vivaldi antenna with a slotted structure and a loaded director according to claim 1, characterized in that, The width of each of the plurality of annular directors with lengths arranged in a tapered period is the same, and the length increases by a fixed length.

4. An improved Vivaldi antenna with a slotted structure and a loaded director according to claim 1, characterized in that, The material of the dielectric substrate (2) is "F4B", with a dielectric constant r = 2.6 and a loss tangent tanδ = 0.0009.

5. An improved Vivaldi antenna with a slotted structure and a loaded director according to claim 1, characterized in that, The coupled feeding structure (3) is composed of a microstrip transmission line (31) and a fan-shaped structure (32) connected; the microstrip transmission line (31) is used to couple and feed the circular groove (10) and the horn-shaped groove (11), and the fan-shaped structure (32) is used for load matching.

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