Three-dimensional ultra-wideband Vivaldi antenna

Abstract

The invention relates to a three-dimensional ultra-wideband Vivaldi antenna, and belongs to the technical field of electromagnetic fields and microwaves. The antenna is expanded in the H-plane direction, and a traditional planar antenna is converted into a three-dimensional antenna, so that the radiation aperture area of the antenna is effectively increased, and the radiation efficiency of the antenna is improved. The antenna comprises a feed structure and a double-radiation structure, the feed structure is composed of a coaxial line, a microstrip line and two microstrip line-to-parallel double lines, and the double-radiation structure is composed of two Vivaldi antennas which are the same in shape and are in mirror symmetry. Under the condition that the size of the E surface of the antenna is kept unchanged, the radiation aperture area is increased through the three-dimensional design, the radiation efficiency of the antenna and the aperture utilization rate of the array antenna are effectively improved, the technical problems that a traditional planar Vivaldi antenna is low in radiation efficiency, and the aperture is wasted during array application are solved, and the antenna is suitable for large-scale popularization and application. And miniaturization of the array antenna can be realized to a certain extent. In addition, the antenna structure form has high universality and can be suitable for antennas in other forms.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic field and microwave technology, and specifically relates to an ultra-wideband antenna structure, especially an ultra-wideband Vivaldi antenna with a three-dimensional structure. Background Technology

[0002] Ultra-wideband electromagnetic pulse (UWSP) is a time-domain electromagnetic signal with an extremely narrow pulse width and an extremely wide frequency band. Its pulse width can reach the nanosecond or sub-nanosecond level, and its frequency coverage ranges from tens of MHz to several GHz. In recent years, with the development of high-voltage and radio-frequency technologies, UWSP has gained significant popularity in fields such as electronic interference, target recognition, materials research, and security detection, and related research and applications are booming. However, because the UWSP spectrum contains a large number of low-frequency components, the size of UWSP radiating antennas is usually large, which greatly affects and limits the practical engineering applications of UWSP technology. Therefore, miniaturization research on UWSP radiating antennas is urgently needed.

[0003] Unlike traditional antennas, miniaturization of ultra-wideband electromagnetic pulse radiating antennas should be understood as achieving a smaller antenna size while maintaining the same radiation efficiency, or achieving higher radiation efficiency within the same antenna size. The Vivaldi antenna is a non-periodic, tapered, end-fire traveling-wave antenna with theoretically infinite bandwidth, naturally possessing wideband characteristics. In addition, it has advantages such as moderate gain, low sidelobes, lightweight, simple structure, ease of fabrication and integration, and low cost. It can be used independently or as an element in a large-scale array antenna. When used as an element, the Vivaldi antenna often employs a compact arrangement in the E-plane and a larger spacing in the H-plane to reduce mutual coupling between elements. Therefore, in constructing large-scale array antennas, although the Vivaldi antenna itself is a planar antenna, the large element spacing in the H-plane prevents it from fully showcasing the advantages of a planar antenna. In other words, during the arraying process, the Vivaldi antenna occupies the same aperture size as other three-dimensional ultra-wideband antennas such as electromagnetic dipole antennas. Therefore, how to improve the radiation efficiency of the Vivaldi antenna and increase the aperture utilization of the array antenna while occupying the same radiation aperture is one of the technical challenges currently faced by Vivaldi antennas in large-scale arrays. This technical challenge is equivalent to how to obtain higher radiation efficiency within a certain array antenna aperture area, which is the miniaturization problem of antennas and array antennas.

[0004] From the perspective of a single Vivaldi antenna, extending the antenna in the H-plane direction transforms the planar antenna into a three-dimensional antenna. This increases the antenna's radiating aperture area and improves its radiation efficiency without changing the size of the antenna's E-plane. From the perspective of the entire array antenna, extending the antenna in the H-plane direction does not change the overall radiating aperture size of the array antenna. It is equivalent to improving the antenna's radiation efficiency by utilizing the space between array elements. At the same time, the radiation capability of the entire array antenna will also be improved.

[0005] In summary, large-scale Vivaldi antenna arrays face technical challenges such as low radiation efficiency and low array aperture utilization. Therefore, it is necessary to research and design a three-dimensional ultra-wideband Vivaldi antenna that extends the antenna H-plane to convert the traditional planar antenna into a three-dimensional antenna. This would improve the antenna's radiation efficiency and increase the array antenna's aperture utilization without changing the antenna E-plane dimensions. Summary of the Invention

[0006] (a) Technical problems to be solved The present invention aims to solve the technical problems of low radiation efficiency and low aperture utilization when traditional planar Vivaldi antennas are used in arrays, which restricts the engineering application of ultra-wideband electromagnetic pulse technology and the miniaturization of array antennas.

[0007] (II) Technical Solution To address the aforementioned issues, this invention proposes a three-dimensional ultra-wideband Vivaldi antenna. Its core idea lies in splitting the input signal into two through a feeding structure and driving two mirror-symmetrical Vivaldi antenna elements, thereby constructing a three-dimensional radiating structure in the H-plane direction perpendicular to the antenna's E-plane. This effectively increases the aperture area of ​​a single radiating element and improves radiation efficiency without increasing the array layout aperture.

[0008] The technical solution of the present invention is as follows: The three-dimensional ultra-wideband Vivaldi antenna includes a feeding structure and a dual-radiating structure.

[0009] The power distribution structure consists of a coaxial line, a microstrip line, and two parallel microstrip line-to-coaxial lines. The coaxial line comprises an outer conductor, an inner conductor, and an internal dielectric, with a characteristic impedance of 50 ohms. The plane containing the microstrip line is perpendicular to the axis of the coaxial line and includes a ground plane, a conductor strip, and a dielectric substrate, with a characteristic impedance of 100 ohms. The outer conductor at one end of the coaxial line is connected to the ground plane of the microstrip line, while the inner conductor at the same end passes through the center of the microstrip line and connects to the conductor strip. Together, they form a power divider structure that converts a 50-ohm coaxial line into two parallel 100-ohm microstrip lines. The two parallel microstrip line-to-coaxial lines are placed parallel to each other on either side of the microstrip line. Each includes a microstrip conductor strip, a ground plane with a gradient transition, and a dielectric substrate, and they are mirror-symmetrical about the axis of the coaxial line. The microstrip conductor strip, the ground plane with a gradient transition, and the dielectric substrate of the two parallel microstrip line-to-coaxial lines are connected to the ends of the conductor strip, ground plane, and dielectric substrate of the microstrip line, respectively, at 90-degree angles to them. In the microstrip-to-parallel bilinear structure, the width of the microstrip conductor is the same as the width of the microstrip conductor; the width of the ground plane with a gradual transition is the same as the width of the microstrip ground plane at the connection position, and gradually narrows along the length of the microstrip conductor until the width is the same as the width of the microstrip conductor, thus forming a parallel bilinear structure.

[0010] The dual-radiating structure consists of two identical Vivaldi antennas, each connected to a microstrip-to-parallel bilinear structure. These two antennas are placed parallel to each other and mirror-symmetrical about the coaxial axis, thus representing extensions of the two microstrip-to-parallel bilinear structures along the coaxial axis. Each Vivaldi antenna includes a top radiating patch, a bottom radiating patch, and a dielectric substrate. The top and bottom radiating patches are printed on opposite sides of the dielectric substrate and are centrally symmetrical about the substrate's radiation axis. The outline of each radiating patch includes an inner exponentially tapered line and an outer exponentially tapered line, ending at the outer boundary of the dielectric substrate. The inner exponentially tapered lines of the top and bottom radiating patches together form a horn-shaped opening that radiates outwards. At the other end of the horn-shaped opening, the top radiating patch is connected to the microstrip conductor in the microstrip-to-parallel bilinear structure on the same side, and the bottom radiating patch is connected to the ground plane in the same microstrip-to-parallel bilinear structure.

[0011] Furthermore, the material of the dielectric substrate can be selected according to the actual situation, and all dielectric substrates should maintain the same material and thickness.

[0012] Furthermore, the coaxial line coincides with the main radiation axis of the antenna.

[0013] Furthermore, the characteristic impedances of the coaxial line and the microstrip line can be selected according to actual needs, and the characteristic impedance of the microstrip line must be twice that of the coaxial line to achieve impedance matching in the power division process.

[0014] Furthermore, the conduction band width in the microstrip line and the microstrip line to parallel bilinear structure can be calculated from the characteristic impedance of the microstrip line based on the relative permittivity and thickness of the selected dielectric substrate.

[0015] Furthermore, the width of the dielectric substrate in the microstrip line is greater than or equal to the width of the ground plane in the microstrip line.

[0016] Furthermore, the width of the dielectric substrate in the microstrip line to parallel bilinear structure is greater than or equal to the width of the dielectric substrate in the microstrip line.

[0017] Furthermore, in each of the microstrip-to-parallel bilinear structures, the microstrip conductors are simultaneously located on one side of the two dielectric substrates, and correspondingly, the ground planes with gradual transitions are simultaneously located on the opposite side of the two dielectric substrates.

[0018] Furthermore, when the top radiating patch of each Vivaldi antenna is simultaneously located on one side of the two dielectric substrates, the bottom radiating patch must simultaneously be located on one side of the two dielectric substrates facing outwards; or, when the top radiating patch is simultaneously located on one side of the two dielectric substrates facing outwards, the bottom radiating patch must simultaneously be located on one side of the two dielectric substrates facing inwards.

[0019] Furthermore, the gradient of the ground plane with a gradient transition in the microstrip line to parallel bilinear structure can be linear gradient, exponential gradient, elliptical gradient, etc.

[0020] Furthermore, the outline of the radiating patch is generally an exponential gradient line, but it can also be a curve in the form of a linear gradient or an elliptical gradient.

[0021] Furthermore, the right-angle connection can be chamfered.

[0022] Furthermore, the width of the horn-shaped opening is less than or equal to the width of the Vivaldi antenna dielectric substrate.

[0023] Furthermore, the width of the two Vivaldi antennas in the dual-radiation structure can be greater than or equal to the width of the dielectric substrate in the microstrip line to parallel double-line structure.

[0024] Furthermore, the microstrip line, the microstrip line to parallel bilinear structure, and each radiating patch use metals of the same thickness.

[0025] Furthermore, different shaped grooves can be cut on each of the radiating patches to improve the surface current distribution of the antenna and enhance its radiation performance.

[0026] Furthermore, the inner spacing between the two Vivaldi antennas in the dual-radiation structure is the same as the length of the microstrip line conductor, and the outer spacing is the same as the length of the microstrip line ground plane. The spacing and the length of the microstrip conductor in the microstrip line to parallel dual-line structure can be reasonably selected according to actual needs and through numerical simulation, etc. The medium filled in between is generally air, but other suitable media can also be selected.

[0027] Furthermore, the two Vivaldi antennas in the dual-radiation structure and the microstrip line to parallel dual-line structure on the same side can share the same dielectric substrate in actual manufacturing.

[0028] Furthermore, each Vivaldi antenna in the dual-radiation structure can be designed as an E-plane dual-slot antenna to further improve the radiated wavefront and enhance the radiation capability.

[0029] (III) Beneficial Effects Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention provides a three-dimensional ultra-wideband Vivaldi antenna, which transforms a traditional planar antenna into a three-dimensional antenna by extending it in the H-plane direction. While keeping the size of the antenna's E-plane unchanged, it effectively increases the antenna's radiating aperture area, thereby improving the antenna's radiation efficiency.

[0030] 2. The three-dimensional ultra-wideband Vivaldi antenna provided by this invention can effectively utilize the space of the array elements in the H-plane direction when used to construct an array antenna. Without changing the aperture area of ​​the array antenna, it can enhance the overall radiation performance of the array antenna, improve the aperture utilization rate of the array antenna, and achieve miniaturization of the array antenna to a certain extent.

[0031] 3. The three-dimensional ultra-wideband Vivaldi antenna provided by this invention has a structure and concept that can be applied to other types of antennas, and has strong flexibility and versatility. Attached Figure Description

[0032] Figure 1 This invention provides a schematic diagram of the structure of a three-dimensional ultra-wideband Vivaldi antenna; Figure 2 A schematic diagram of a three-dimensional ultra-wideband Vivaldi antenna feeding structure provided by the present invention; Figure 3 A cross-sectional view of a three-dimensional ultra-wideband Vivaldi antenna feed structure provided by the present invention; Figure 4 A schematic diagram of the dual-radiating structure of a three-dimensional ultra-wideband Vivaldi antenna provided by the present invention; Figure 5A schematic diagram of a three-dimensional ultrawideband Vivaldi antenna microstrip line to parallel double-line structure and a single-sided radiating structure provided by the present invention. Figure 6 A cross-sectional view of a three-dimensional ultra-wideband Vivaldi antenna provided for this invention; Figure 7 A schematic diagram of a conventional Vivaldi antenna used as a comparison in an embodiment of a three-dimensional ultra-wideband Vivaldi antenna provided by the present invention; Figure 8 The excitation waveform provided in an embodiment of a three-dimensional ultra-wideband Vivaldi antenna according to the present invention; Figure 9 A comparison of the far-field radiation field waveforms of a single antenna principal axis in an embodiment of a three-dimensional ultra-wideband Vivaldi antenna provided by the present invention; Figure 10 A schematic diagram of a two-element array in an embodiment of a three-dimensional ultra-wideband Vivaldi antenna provided by the present invention; Figure 11 A comparison of the far-field radiation field waveforms of the two-element array main axis in an embodiment of the three-dimensional ultra-wideband Vivaldi antenna provided by the present invention.

[0033] in: 1-Feeding structure: 11-Coaxial cable, 111-Outer conductor of coaxial cable, 112-Inner conductor of coaxial cable; 12 - Microstrip line, 121 - Conductor strip in microstrip line, 122 - Ground plane in microstrip line, 123 - Dielectric substrate in microstrip line; 13, 14 - Two microstrip line to parallel bilinear structure; 131 - Microstrip conductor in microstrip line to parallel bilinear structure; 132 - Ground plane with a gradient transition form; 133 - Dielectric substrate in microstrip line to parallel bilinear structure.

[0034] 2-Double-radiation structure: 21, 22 - Two Vivaldi antennas; 211 - Top radiating patch of Vivaldi antenna 21; 212 - Bottom radiating patch of Vivaldi antenna 21; 213 - Dielectric substrate of Vivaldi antenna 21; 214 - Inner exponential gradient line of top radiating patch 211; 215 - Outer exponential gradient line of top radiating patch 211; 216 - Boundary of dielectric substrate 213. Detailed Implementation

[0035] The technical solution provided by the present invention will be described and explained in detail below with reference to the accompanying drawings.

[0036] like Figure 1As shown, the three-dimensional ultra-wideband Vivaldi antenna provided by the present invention includes a feeding structure 1 and a dual-radiating structure 2.

[0037] like Figure 2 , 3 As shown, the power supply structure 1 consists of four parts: a coaxial line 11, a microstrip line 12, and two microstrip line-to-parallel bi-line structures 13 and 14. The coaxial line 11 includes an outer conductor 111, an inner conductor 112, and an internal dielectric. The microstrip line 12 includes a conductor strip 121, a ground plane 122, and a dielectric substrate 123. The plane of the microstrip line 12 is perpendicular to the axis of the coaxial line 11. The conductor strip 121 is horizontal, and its width in the vertical direction is... w 1. The length in the horizontal direction is l 1. The width of the floor 122 is w 2, length is l 2. The thickness of the dielectric substrate 123 is d 1. The width is greater than or equal to the width of the ground plane 122 (the heights of the two are the same in the attached figure); one end of the outer conductor 111 of the coaxial line 11 is connected to the ground plane 122 of the microstrip line 12, and the same end of the inner conductor 112 passes through the center of the microstrip line 12 and is connected to the microstrip line conductor 121. The characteristic impedance of the coaxial line is 50 ohms, and the characteristic impedance of the microstrip line 12 is 100 ohms. This constitutes a coaxial line to microstrip line power divider structure, that is, power is fed from one end of the coaxial line 11 and output from the left and right sides of the microstrip line 12.

[0038] like Figure 2 , 3 As shown, two microstrip line to parallel double-line structures 13 and 14 are placed on both sides of microstrip line 12, and these two structures are mirror-symmetrical about the axis of coaxial line 11.

[0039] Taking the microstrip line to parallel double-line structure 13 as an example, its composition is explained as follows: Figure 2 , 3 As shown, the microstrip line to parallel dual-line structure 13 includes a microstrip conductor 131, a ground plane 132 with a gradient transition, and a dielectric substrate 133. The microstrip conductor 131 is connected to the right side of the conductor 121 of the microstrip line 12, and its width is the same as that of the conductor 121. w 1. The length along the coaxial line 11 is l 3. It is at a 90-degree angle to the conductor 121; the ground plane 132 with a gradual transition is connected to the right side of the ground plane 122 of the microstrip line 12, also at a 90-degree angle to 122, and the width of the connection is the same as that of 122. w2. The width of the microstrip conductor 131 gradually narrows along its length, eventually forming a parallel double line with 131; the dielectric substrate 133 is connected to the dielectric substrate 123 of the microstrip line 12 and is made of the same material, and is also connected to 123 at a 90-degree angle. The width of the dielectric substrate 133 is... w 3, thickness is d 1, that is, the thickness is the same as that of the dielectric substrate 123 of the microstrip line 12.

[0040] like Figure 2 , 3 As shown, the inner spacing of the two microstrip line-to-parallel bilinear structures 13 and 14 is consistent with the length of the conduction band 121 in microstrip line 12. l 1. The outer spacing is consistent with the length of the ground plane 122 in the microstrip line 12, which is... l 2.

[0041] like Figure 1 , 4 As shown, the double-radiating structure 2 includes two identical shapes and about E - k The Vivaldi antennas 21 and 22 are planar mirror-symmetric antennas, both consisting of two microstrip line-to-parallel bilinear structures 13 and 14, in the radiation direction... k The extension of direction.

[0042] The Vivaldi antenna 21 is used as an example to illustrate its specific composition, such as... Figure 5 As shown, a microstrip line to parallel dual-line structure 13 and a Vivaldi antenna 21 are illustrated. The Vivaldi antenna 21 consists of a top radiating patch 211, a bottom radiating patch 212, and a dielectric substrate 213. The top radiating patch 211 and the bottom radiating patch 212 are printed on the front and back sides of the dielectric substrate 213, respectively, and are positioned relative to the dielectric substrate 213 in the radiation direction (i.e.,...). Figure 5 As shown k The radiating patch is symmetrical about the axis in the direction of the radiation. The outline of each radiating patch includes two exponential gradient lines; for example, the top radiating patch 211 includes an inner exponential gradient line 214 and an outer exponential gradient line 215, and is located outside the dielectric substrate 213. Figure 5 The boundary 216 shown is the cutoff point. The exponentially gradient lines on the inner sides of the top surface radiating patch 211 and the bottom surface radiating patch 212 form a funnel-shaped opening pointing in the radiation direction, with an opening width of... w 4; and on the other side of the radiation direction, that is Figure 5 shown OAt the point of contact, the top radiating patch 211 is connected to the microstrip conductor 131 in the microstrip-to-parallel dual-line structure 13, and the bottom radiating patch 212 is connected to the ground plane 132 with a gradient transition. In actual fabrication, the Vivaldi antenna 21 and the microstrip-to-parallel dual-line structure 13 share the same dielectric substrate, that is, 213 and 133 are the same dielectric substrate. Therefore, the width of the Vivaldi antenna 21 is the same as the width of the dielectric substrate 133. w 3. The length of the Vivaldi antenna 21 is l 4.

[0043] Based on the Vivaldi antenna 21, the Vivaldi antenna 22 can be obtained through mirror symmetry, and the Vivaldi antenna 22 is connected to the microstrip line to parallel double-line structure 14, thereby completing the construction of the three-dimensional ultra-wideband Vivaldi antenna provided by the present invention.

[0044] like Figure 6 The diagram shown is a cross-sectional view of a three-dimensional ultra-wideband Vivaldi antenna provided by the present invention. The Vivaldi antenna 21 and the microstrip-to-parallel dual-wire structure 13 share the same dielectric substrate. The combination of the two is equivalent to a conventional Vivaldi antenna with a port impedance of 100 ohms and a microstrip-to-parallel dual-wire feed, with a length of [missing information]. l 3+ l 4, width is w 3. The thickness of the dielectric substrate is d 1.

[0045] The above structure is only a basic form of a three-dimensional ultra-wideband Vivaldi antenna provided by the present invention. Slots can be made on each Vivaldi antenna radiating patch to further improve the current distribution on the antenna surface and enhance the radiation efficiency. Alternatively, an E-plane dual-slot Vivaldi antenna can be used to replace the above-mentioned Vivaldi antennas, but this is not the focus of the present invention.

[0046] The working principle and process of the three-dimensional ultra-wideband Vivaldi antenna provided by this invention are as follows: like Figure 1As shown, an ultra-wideband high-voltage pulse is fed into the coaxial line 11, split into two paths via microstrip line 12, and then fed to Vivaldi antennas 21 and 22 respectively through two microstrip line-to-parallel double-line structures 13 and 14. The two Vivaldi antennas then radiate outwards together. The coaxial line 11 has a characteristic impedance of 50 ohms, and the microstrip line 12 has a characteristic impedance of 100 ohms. Together, they form a power divider structure, which feeds two Vivaldi antennas with a port characteristic impedance of 100 ohms each through the two microstrip line-to-parallel double-line structures. Compared to traditional planar Vivaldi antennas, this invention extends the antenna in the H-plane direction, increasing the antenna's radiating aperture area and thus improving the antenna gain, which translates to higher radiation efficiency in the time domain. In particular, when used as array elements to construct an array antenna, the space between the elements can be fully utilized, improving the aperture utilization of the array antenna while maintaining its radiating aperture, thereby achieving miniaturization of the array antenna.

[0047] Example The embodiments of the present invention will now be further described with reference to specific parameters.

[0048] like Figure 1 As shown, a three-dimensional ultra-wideband Vivaldi antenna consists of a feed structure 1 and a dual-radiating structure 2. All dielectric substrates used are FR4 substrates with a thickness of [missing information - likely a thickness value]. d 1 = 2 mm.

[0049] like Figure 1 , 2 As shown in Figures 1 and 3, the feed structure 1 consists of a coaxial line 11, a microstrip line 12, and two microstrip line-to-parallel bi-line structures 13 and 14. The characteristic impedance of the coaxial line 11 is 50 ohms, and the characteristic impedance of the microstrip line 12 is 100 ohms. Its conductor strip 121 is horizontal, i.e., in the H-plane direction, with a width of [missing information]. w 1 = 0.9 mm, length is l 1 = 48 mm, the width of the microstrip ground plane 122 is w 2 = 80 mm, length is l 2 = 52 mm. Regarding positional relationships, the axial direction of coaxial line 11 is at... k In the direction, and coinciding with the principal axis of radiation, microstrip line 12 is located E - H A plane perpendicular to the coaxial line 11 is constructed. The inner conductor 112 of the coaxial line 11 passes through the center of the microstrip line 12 and connects to the conductor 121 of the microstrip line 12. The outer conductor 111 is connected to the ground plane 122. This constructs a power divider structure that transforms a 50-ohm coaxial line into two parallel 100-ohm microstrip lines. The plane containing the two microstrip lines transforming into parallel bi-line structures 13 and 14 is perpendicular to the plane of the coaxial line 11. E - kThe planes are parallel to each other, located on both sides of microstrip line 12, both at 90 degrees to microstrip line 12, and about... E - k Planar mirror symmetry. In each microstrip-to-parallel dual-line structure, the microstrip conductor, dielectric substrate, and ground plane are correspondingly connected to the conductor, dielectric substrate, and ground plane in microstrip line 12. The width of the microstrip conductor is the same as the width of the conductor in microstrip line 12. w 1 = 0.9 mm; the width of the ground plane with a gradual transition is consistent with the width of the ground plane in microstrip line 12, which is w 2=80mm, its width along k The width gradually narrows in the direction and eventually forms a parallel double line with the microstrip conduction band, meaning the width at the tail end is... w 1=0.9mm, microstrip conductor and ground plane with gradual transition in k The length in both directions is l 3 = 45 mm; the width of the dielectric substrate in each microstrip line to parallel double-line structure is w 3 = 240 mm, in k The length in the direction is also l 3 = 45 mm.

[0050] like Figure 2 , 3 As shown, the inner spacing of the two microstrip line-to-parallel bilinear structures in the H-plane direction is consistent with the conduction band length of microstrip line 12. l 1 = 48 mm, and the outer spacing is consistent with the ground plane length of microstrip line 12, which is l 2 = 52 mm.

[0051] like Figure 1 , 4 As shown in Figures 5 and 6, the double-radiating structure 2 includes two [structures related to...]. E - k The Vivaldi antennas 21 and 22 are planar mirror-symmetric antennas, both identical in shape and consisting of two microstrip line-to-parallel bilinear structures 13 and 14. k Extension in direction k Length in direction l 4 = 280 mm, and the width in the E-plane direction is consistent with the width of the dielectric substrate in the microstrip line to parallel double-line structure. w 3 = 240 mm. Each Vivaldi antenna consists of a top radiating patch, a bottom radiating patch, and a dielectric substrate. The two radiating patches are identical in shape and their dimensions relative to the dielectric substrate are... k The axes in the direction are centrally symmetrical. Figure 6 In O Let point be the origin of the coordinate system, and let the coordinates of the exponential gradient line be ( ).x k , y E If the inner exponential gradient lines constituting the top surface radiating patch are then... y E =0.5 exp(0.0193 x k -0.95, the equation of the outer exponential gradient line is y E =0.5 exp(0.1827 x k -0.05, the width of the trumpet-shaped opening formed by the inner exponentially gradient lines of the top and bottom radiating patches is w 4 = 220 mm, which is less than the width of the dielectric substrate. w 3.

[0052] To compare the improved radiation efficiency of the antenna described in this invention compared to a conventional Vivaldi antenna, a Vivaldi antenna with a dual-radiating structure is used as a control, such as... Figure 7 As shown, it uses a conventional 50-ohm feed instead of 100 ohms. This invention provides an antenna and... Figure 7 The antennas shown are all fed with a zero-order Gaussian pulse with a voltage amplitude of 7.07 V and a half-width of 0.16 ns, as follows: Figure 8 As shown. The radiated electric field waveform at a position 5 m on the principal axis was obtained through numerical simulation, as shown. Figure 9 As shown in the figure, the peak-to-peak value of the radiation field waveform of a conventional Vivaldi antenna is 2.4 V / m, while the peak-to-peak value of the radiation field waveform of the antenna described in this invention at the same field point is 2.8 V / m, which represents a 16% improvement in time-domain radiation efficiency.

[0053] To illustrate the advantages of the antenna described in this invention when used as an array element in constructing an array antenna, a two-element array in the H-plane direction was constructed, as follows: Figure 10 As shown, the distance between their principal axes D =200 mm. Similarly, using... Figure 7 The Vivaldi antenna shown is constructed with a similar two-element array layout for comparison. The radiation field waveforms at 5 m along the principal axis of each two-element array, obtained from numerical simulation, are as follows: Figure 11 As shown, the peak-to-peak value of the radiation field waveform of a conventional Vivaldi antenna array is 4.7 V / m, while the peak-to-peak value of the radiation field waveform of the antenna array described in this invention is 5.6 V / m, which improves the time-domain radiation efficiency by more than 19%.

[0054] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A three-dimensional ultra-wideband Vivaldi antenna, characterized in that, It includes a power feeding structure (1) and a double-radiating structure (2); The power supply structure (1) consists of a 50-ohm coaxial line (11), a 100-ohm microstrip line (12), and two microstrip line-to-parallel double-line structures (13, 14). The plane of the microstrip line (12) is perpendicular to the axial direction of the coaxial line (11). The outer conductor (111) at one end of the coaxial line (11) is connected to the microstrip line ground plane (122), and the inner conductor (112) at the same end passes through the center of the microstrip line (12) and is connected to the microstrip line conductor (121), thus forming a power divider structure from a 50-ohm coaxial line to two 100-ohm microstrip lines in parallel. The two microstrip line to parallel biline structures (13, 14) are extensions of the 100-ohm microstrip line (12), respectively placed on both sides of the microstrip line (12) at a 90-degree right angle to the microstrip line (12). Each structure includes a conductor strip (131), a dielectric substrate (133), and a ground plane (132) with a gradient transition form. They are respectively connected to the conductor strip (121), dielectric substrate (123), and ground plane (122) of the microstrip line (12). The width of the ground plane (132) with a gradient transition form is the same as the width of the microstrip line ground plane (122) at the connection position, and the width gradually narrows in the length direction of the conductor strip (131) until the width is the same as the width of the conductor strip (131), forming a parallel biline structure. The dual-radiating structure (2) consists of two identical Vivaldi antennas (21, 22), which are connected to two microstrip line-to-parallel dual-line structures (13, 14) respectively. The two are placed in parallel and are mirror-symmetrical about the axis of the coaxial line (11). Each Vivaldi antenna includes a top radiating patch (211), a bottom radiating patch (212), and a dielectric substrate (213). The top radiating patch (211) and the bottom radiating patch (212) are printed on the front and back sides of the dielectric substrate (213) respectively, and are centrally symmetrical about the axis of the dielectric substrate (213) along the radiation direction. The top radiating patch (211) and the bottom radiating patch (212) together form a horn-shaped opening and radiate outward.

2. The three-dimensional ultra-wideband Vivaldi antenna according to claim 1, characterized in that, The ground plane (132) with a gradual transition in the microstrip line to parallel bilinear structure (13, 14) can be linear, exponential, or elliptical.

3. The three-dimensional ultra-wideband Vivaldi antenna according to claim 1, characterized in that, The outlines of the top surface radiating patch (211) and the bottom surface radiating patch (212) are exponential gradient curves, linear gradient curves or elliptical gradient curves.

4. The three-dimensional ultra-wideband Vivaldi antenna according to claim 1, characterized in that, The feeding structure (1) and the dielectric substrate (123, 133, 213) in the dual-radiation structure (2) are made of the same material, and the axial direction of the coaxial line (11) coincides with the main radiation axis of the antenna.

5. A three-dimensional ultra-wideband Vivaldi antenna according to claim 1, characterized in that, The characteristic impedance of the coaxial line (11) is 50 ohms, and the characteristic impedance of the microstrip line (12) is 100 ohms. The characteristic impedance of the microstrip line (12) is twice that of the characteristic impedance of the coaxial line (11) to achieve impedance matching in the power division process.

6. A three-dimensional ultra-wideband Vivaldi antenna according to claim 1, characterized in that, The width of the dielectric substrate (123) in the microstrip line (12) is not less than the width of the ground plane (122) in the microstrip line (12); the width of the dielectric substrate (133) in the microstrip line to parallel double-line structure (13, 14) is not less than the width of the dielectric substrate (123) in the microstrip line (12).

7. A three-dimensional ultra-wideband Vivaldi antenna according to claim 1, characterized in that, In each of the microstrip line to parallel bilinear structures (13, 14), the microstrip conductor (131) is located on one side of the two dielectric substrates (133) inwards, and correspondingly, the ground plane (132) with a gradient transition form is located on one side of the two dielectric substrates (133) outwards.

8. A three-dimensional ultra-wideband Vivaldi antenna according to claim 1, characterized in that, When the top surface radiating patch (211) of each Vivaldi antenna (21, 22) is simultaneously located on the inner side of the dielectric substrate (213), the bottom surface radiating patch (212) is located on the outer side of both dielectric substrates (213); and vice versa.

9. A three-dimensional ultra-wideband Vivaldi antenna according to claim 1, characterized in that, The right-angle connection between the microstrip line (12) and the microstrip line to parallel double-line structure (13, 14) is chamfered.

10. A three-dimensional ultra-wideband Vivaldi antenna according to claim 1, characterized in that, The radiating patches (211, 212) are provided with grooves of different shapes to improve the surface current distribution of the antenna and enhance its radiation performance.

11. A three-dimensional ultra-wideband Vivaldi antenna according to claim 1, characterized in that, The inner spacing between the two Vivaldi antennas (21, 22) in the dual-radiation structure (2) is the same as the length of the microstrip conductor (121), and the outer spacing is the same as the length of the microstrip ground plane (122). This spacing and the length of the microstrip conductor (131) in the microstrip-to-parallel dual-line structure (13, 14) are selected through numerical simulation, and the medium filled between them is air or other suitable medium.

12. A three-dimensional ultra-wideband Vivaldi antenna according to claim 1, characterized in that, The Vivaldi antennas (21, 22) in the dual-radiation structure (2) adopt the form of E-plane dual-slot antennas to further improve the radiation wavefront and enhance the radiation capability.

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