A miniaturized self-decoupling ultrawideband Vivaldi antenna

Abstract

This invention proposes a miniaturized, self-decoupled ultra-wideband Vivaldi antenna, belonging to the field of electromagnetic fields and microwave technology. It aims to solve the problem of simultaneously achieving mutual coupling suppression, miniaturization, and improved radiation characteristics in existing Vivaldi antenna array applications. The antenna includes a feed structure, a radiating structure, and an extended ground structure. The feed structure is a transitional structure from a microstrip transmission line to a parallel double-line transmission line. The radiating structure is a horn-shaped opening structure with a gradient profile and radiating slots. The extended ground structure consists of extended ground patches printed on two surfaces of a dielectric substrate and electrically connected to the ground plane of the feed structure, each with a gradient profile and slots. This invention, without increasing the antenna size or decoupling structure, utilizes the extended ground structure to reconstruct the coupling path, achieving low-frequency bandwidth extension and effective decoupling between E-plane elements, while simultaneously improving low-frequency gain and front-to-back ratio. It is primarily applied to ultra-wideband detection, communication, and imaging systems.

Description

Technical Field

[0001] This invention belongs to the field of antenna technology, specifically relating to a Vivaldi antenna for use in ultra-wideband detection, communication and imaging systems, and more particularly to an ultra-wideband Vivaldi antenna with miniaturization and self-decoupling characteristics. Background Technology

[0002] The tapered slot antenna, also known as the Vivaldi antenna, is a typical planar end-fire antenna. Due to its relatively stable phase center and advantages such as ultra-wideband, high gain, good directivity, lightweight design, and ease of integration, it is often used as a radiating antenna for nanosecond-level ultra-wideband microwave pulses and is widely applied in fields such as non-destructive target detection or imaging, deliberate electromagnetic interference, and ultra-wideband short-range communication. This antenna can be used as a standalone radiating element or as an element in a large-scale array antenna, further enhancing the antenna system gain through array configuration.

[0003] When Vivaldi antennas are arrayed, as with other antennas, the mutual coupling effect between array elements becomes a key factor affecting and limiting the performance of the antenna system. Mutual coupling can lead to antenna port impedance mismatch, radiation pattern distortion, and gain reduction. In particular, for ultra-wideband microwave pulse radiation, it can also cause problems such as time-domain waveform distortion.

[0004] For Vivaldi antenna arrays, there are generally two approaches to handling the mutual coupling between their elements. The first is to utilize coupling, i.e., tight coupling, by enhancing the capacitive coupling between adjacent elements in the E-plane direction to construct a continuous current sheet, thereby expanding the operating bandwidth and enhancing radiation performance. However, due to the enhanced coupling between adjacent elements, a large coupling voltage can easily be generated during ultra-wideband microwave pulse radiation, which may damage the feed. The second approach is to suppress coupling, i.e., decoupling. For example, electromagnetic bandgap structures or defective ground structures can be loaded between elements to isolate electromagnetic coupling through band-stop characteristics, or neutral lines or parasitic elements can be introduced between adjacent elements to construct additional coupling paths for coupling cancellation. However, these methods all require the design and addition of additional decoupling structures, which will lead to an increase in antenna profile height and manufacturing complexity. In addition, mutual coupling can also be reduced by increasing the element spacing, but this results in a significant increase in the array aperture area, which cannot meet the practical requirements of system miniaturization and high-density integration.

[0005] On the other hand, the low-frequency cutoff frequency of a Vivaldi antenna is usually determined by the maximum size of its horn-shaped opening. Extending the low frequency often means increasing the physical size of the antenna, which is inherently contradictory to the miniaturization and dense arraying of array antennas. In addition, traditional Vivaldi antennas have strong back radiation, which will cause energy to leak backward and cause unnecessary electromagnetic interference.

[0006] In summary, there is an urgent need for a new structure that can effectively extend the low-frequency operating bandwidth, suppress mutual coupling between array elements, and improve radiation characteristics such as front-to-back ratio without increasing the antenna size and decoupling structure, so as to solve the various technical challenges faced in the current design of ultra-wideband array antennas. Summary of the Invention

[0007] (a) Technical problems to be solved The present invention aims to solve the problem that existing Vivaldi antennas in array applications are difficult to achieve simultaneously expanding low-frequency operating bandwidth, suppressing mutual coupling between array elements, and improving radiation performance without increasing antenna size, increasing manufacturing complexity, or introducing additional decoupling structures.

[0008] (II) Technical Solution To address the aforementioned issues, this invention proposes a miniaturized, self-decoupled, ultra-wideband Vivaldi antenna. The core idea is to extend the ground plane of the microstrip transmission line in the feed structure, constructing an extended ground structure, based on the traditional Vivaldi antenna topology. This structure, while maintaining the overall antenna size, extends the surface current path to extend to lower frequencies, reconstructs the electromagnetic coupling path between array elements to suppress E-plane mutual coupling, and improves the antenna's front-to-back ratio.

[0009] The specific technical solution of the present invention is as follows: A miniaturized, self-decoupled, ultrawideband Vivaldi antenna includes a feeding structure 1, a radiating structure 2, and an extended ground structure 3. The antenna's long edge... x Direction, length l wide edge y Direction, width w .

[0010] The feed structure 1 is a transition structure from a microstrip transmission line 11 to a parallel bi-line transmission line 12. The microstrip transmission line 11 consists of a long strip conductor 111, a dielectric substrate 4, and a ground plane 112. The long strip conductor 111 and the ground plane 112 are printed on the top and bottom surfaces of the dielectric substrate 4, respectively. The width of the ground plane 112 gradually narrows along the length of the long strip conductor 111 until it matches the width of the long strip conductor 111, thus forming the parallel bi-line transmission line 12. The characteristic impedance of the microstrip transmission line 11 is generally selected as 50 Ω, but can be selected according to actual design requirements. The width of the conductor 111... w f The characteristic impedance of the microstrip transmission line can be calculated using the microstrip line characteristic impedance formula based on the selected microstrip transmission line characteristic impedance, the thickness of the dielectric substrate 4, and the relative permittivity.

[0011] The radiating structure 2 is a funnel-shaped opening structure, including a dielectric substrate 4 and a top surface radiating patch 21 and a bottom surface radiating patch 22 printed on the upper and lower surfaces of the dielectric substrate 4. The outline of the top surface radiating patch 21 consists of a longer gradient line 211, a shorter gradient line 212, and a radiating groove line 213. The longer gradient line 211 extends along... x The length in the direction is l a ,along y The width of the direction is w / 2+ w f / 2, shorter gradient line 212 along x The length of the direction is l b ,along y The width of the direction is w / 2- w f / 2. The introduction of the radiating slot line 213 forms multiple radiating slots on the top radiating patch 21 to improve the current distribution on the antenna surface. The bottom radiating patch 22 has the same structure as the top radiating patch 21, and its outline includes a longer gradient line 221, a shorter gradient line 222, and a radiating slot line 223. The whole is rotationally symmetrical about the central axis of the conductor strip 111 along its length. At the starting position of the gradient outline line of each radiating patch, the radiating structure 2 is connected to the parallel double-line transmission line 12 of the feeding structure 1, thereby completing the feeding of the radiating structure 2.

[0012] The extended ground structure 3 includes a top-side extended ground patch 31 and a bottom-side extended ground patch 32, both of which are extensions of the microstrip transmission line ground plane 112 in the feed structure 1 towards the flared opening of the radiation structure 2. The top-side extended ground patch 31 is printed on the top surface of the dielectric substrate 4, and its outline consists of an extended ground gradient line 311 and an extended ground groove line 312. This patch is electrically connected to the microstrip transmission line ground plane 112 located on the bottom surface of the dielectric substrate 4 through a metal via 33. The bottom-side extended ground patch 32 has the same structural form as the top-side extended ground patch 31, exhibiting 180° rotational symmetry about the central axis of the conductor strip 111's length direction. It is printed on the bottom surface of the dielectric substrate 4 and is directly connected to the microstrip transmission line ground plane 112 because it is located on the same bottom surface. Each extended ground patch... x The length in the direction is l g At the location where it connects to the ground plate 112 y The width of the direction is w g .

[0013] The dielectric substrate 4 in the power supply structure 1, radiation structure 2 and extended ground structure 3 is a single rectangular dielectric board, the material and thickness of which can be determined according to the actual situation such as design requirements and usage requirements.

[0014] The width of the microstrip transmission line ground plane 112 gradually narrows along the length of the conductor strip 111. The narrowing method can be exponential gradual narrowing, elliptical gradual narrowing, etc.

[0015] The longer gradient lines 211 and 221 and the shorter gradient lines 212 and 222 of each radiating patch in radiating structure 2 can be exponential, linear, or elliptical curve gradients, etc. The specific gradient method can be selected based on the preferred technical specifications. The radiating groove lines 213 and 223 in the outline of each radiating patch in radiating structure 2 can be parametric curves such as sine curves, or periodic rectangular, triangular, or semi-elliptical groove lines, etc. The specific form and number of radiating groove lines can be selected based on the preferred technical specifications.

[0016] The gradient lines 311 and 321 of each extended ground patch in the extended ground structure 3 can be exponential, linear, or elliptical curves. The extended ground trench lines 312 and 322 can be parametric curves such as sine curves, or periodic rectangular, triangular, or semi-elliptical trench lines. They can be consistent with the form of the radial trench lines 213 and 223 in the radial structure 2, or they can be different, or straight lines can be used instead of trench lines.

[0017] In extended ground structure 3, the length of each extended ground patch in the direction of the trumpet-shaped opening. l g The length of the longer gradient line of each radiating patch in radiating structure 2 in that direction shall not exceed the length of the longer gradient line in that direction. l a Half of; the width in the direction perpendicular to the direction of the trumpet-shaped opening. w g The width of the shorter gradient line of the top surface radiating patch 21 in that direction is smaller than that of the radiating patch 21. When the extended ground structure 3 uses straight segments instead of grooves, the number of extended ground grooves 312 and 322 can be the same as the number of radiating grooves 213 and 223, or they can be different.

[0018] The working process and principle of the miniaturized self-decoupling ultrawideband Vivaldi antenna provided by this invention are as follows: The excitation signal is transmitted to the horn-shaped radiating structure 2 via microstrip transmission line 11 and parallel double-line transmission line 12 to feed the antenna. The gradient lines of each radiating patch in the radiating structure 2 serve as the main current path for signal propagation and outward radiation. The radiating slots formed by radiating slot lines 213 and 223 improve the surface current distribution of each radiating patch, thereby enhancing the antenna's radiation performance. The extended ground structure 3 is electrically connected to the ground plane 112 in the microstrip transmission line 11. On the one hand, by extending the extended ground structure, the effective path length of the antenna surface current is further extended, thereby enhancing low-frequency radiation performance and extending the low-frequency lower limit. On the other hand, during the E-plane arraying process, the introduction of the extended ground structure 3 reconstructs the electromagnetic coupling path between array elements, thereby reducing the mutual coupling between E-plane array elements. This reduction in mutual coupling is not achieved by adding an additional external decoupling structure, but is contributed by the antenna's own structure. Therefore, this antenna has self-decoupling capability. In addition, extended ground structure 3 improves the front-to-back ratio of the antenna to some extent by reconstructing the current distribution on the antenna surface.

[0019] The underlying physical mechanism of self-decoupling in this invention lies in the following: When two identical antennas are arrayed close together in the E-plane, traditional antennas, lacking effective isolation, allow surface currents coupled from one element to another to flow along the conventional path to their feed ports, resulting in strong mutual coupling. In this invention, the combined effect of the extended ground structure and the extended ground trench line provides a new low-impedance path for the coupled current from adjacent elements, extending deep into the horn opening direction, and effectively perturbing and confining this current. This is equivalent to reconstructing and isolating the main electromagnetic coupling path between elements, confining the coupling energy to the extended ground structure and dissipating it, rather than allowing it to enter the feed structure. Thus, while maintaining the original antenna aperture, the mutual coupling coefficient in the E-plane is significantly reduced, achieving the so-called 'self-decoupling'.

[0020] (III) Beneficial Effects Compared with the prior art, the present invention has the following beneficial effects: 1. This invention extends the ground plane of the microstrip transmission line in the feeding structure, thereby extending the effective path length of the antenna surface current and thus expanding the antenna's operating frequency band to lower frequencies without increasing the antenna size, additional decoupling structure, or significantly increasing the processing complexity, achieving miniaturization. On the other hand, it reconstructs the electromagnetic coupling path between array elements when the E-plane array is assembled, effectively suppressing mutual coupling between array elements and realizing self-decoupling capability.

[0021] 2. This invention makes full use of the blank area on the traditional Vivaldi antenna to extend and expand the patch structure, providing a new basic topology for the design and application of Vivaldi antennas, and achieving better overall performance in the same aperture space.

[0022] 3. The present invention guides and reconstructs the surface current through the constructed extended ground patch, thereby reducing the back radiation of the antenna to a certain extent and significantly improving the front-to-back ratio of the antenna.

[0023] 4. When the antenna proposed in this invention is used as an element of an ultra-wideband Vivaldi antenna array, its self-decoupling characteristics and size advantages enable dense array deployment to a certain extent, effectively improving the utilization rate of the array antenna aperture. Attached Figure Description

[0024] Figure 1 A schematic diagram of a miniaturized self-decoupling ultrawideband Vivaldi antenna structure provided by the present invention; Figure 2 This is a front view; Figure 3 This is a schematic diagram of the top surface structure of the dielectric substrate; Figure 4 This is a schematic diagram of the bottom structure of the dielectric substrate; Figure 5 This is a front view of the E-plane binary array in the embodiment; Figure 6 This is a three-dimensional view of the E-plane binary array in the embodiment; Figure 7 This is a schematic diagram of a conventional antipodal Vivaldi antenna (AVA) used for comparison in the embodiment; Figure 8 This is a schematic diagram of the slotted antipodal Vivaldi antenna (SAVA) used for comparison in the embodiment; Figure 9 This is a comparison diagram of the E-plane two-element array antenna S11 with the other two types of antennas in the embodiment; Figure 10 This is a comparison diagram of the E-plane binary array S21 in the embodiment with two other types of antennas; Figure 11 This is a comparison diagram of the gain of a single element of the E-plane two-element array with that of the other two types of antennas in the embodiment; Figure 12 This is a comparison diagram of the front-to-back ratio of a single element of the E-plane binary array in the embodiment with that of the other two types of antennas; In the picture: 1-Power supply structure, 11-Microstrip transmission line, 111-Long strip conductor of microstrip transmission line, 112-Ground plate of microstrip transmission line, 12-Parallel double-line transmission line; 2-Radiating structure, 21-Top surface radiating patch, 211-Longer gradient line on top surface radiating patch, 212-Shorter gradient line on top surface radiating patch, 213-Radiating groove line on top surface radiating patch, 22-Bottom surface radiating patch, 221-Longer gradient line on bottom surface radiating patch, 222-Shorter gradient line on bottom surface radiating patch, 223-Radiating groove line on bottom surface radiating patch; 3-Extended ground structure, 31-Top surface extended ground patch, 311-Top surface extended ground patch extended ground gradient line, 312-Top surface extended ground patch extended ground groove line, 32-Bottom surface extended ground patch, 321-Bottom surface extended ground patch extended ground gradient line, 322-Bottom surface extended ground patch extended ground groove line, 33-Metal via. 4-Dielectric substrate; 5, 6 - Array elements. Detailed Implementation

[0025] The technical solution provided by the present invention will be described and explained in detail below with reference to the accompanying drawings.

[0026] like Figure 1 , Figure 2 As shown, a miniaturized self-decoupling ultrawideband Vivaldi antenna includes a feed structure 1, a radiating structure 2, and an extended ground structure 3. The antenna is printed on a dielectric substrate 4 made of FR4 substrate material, and is an overall rectangular thin plate. The length of the dielectric substrate 4 is... l =200 mm, width w =60 mm, thickness is 2 mm (thickness is not indicated in the drawing).

[0027] like Figure 1 , Figure 2 , Figure 3 , Figure 4 As shown, the power supply structure 1 consists of a microstrip transmission line 11 and a parallel bilinear transmission line 12. The microstrip transmission line 11 includes a conductor strip 111, a ground plane 112, and a dielectric substrate 4. The conductor strip 111 is located at the center of the wide side of the dielectric substrate 4, i.e., at the position indicated in the figure. x The characteristic impedance of microstrip transmission line 11 is 50 Ω. Based on the formula for calculating the characteristic impedance of a microstrip transmission line and the relative permittivity and thickness of the substrate FR4, the width of the conductor strip 111 can be obtained. w f =1.96mm. The width of the ground plane 112 is the same as the width of the dielectric substrate 4, both being 60 mm, and its width is along... x The direction gradually narrows until its width is consistent with the guide strip 111, forming a parallel double-line transmission line 12. In this embodiment, the narrowing method adopted is an elliptical gradient.

[0028] like Figure 1 , 2As shown in Figures 3 and 4, the radiating structure 2 consists of a dielectric substrate 4 and a top surface radiating patch 21 and a bottom surface radiating patch 22 printed on the upper and lower surfaces of the dielectric substrate. Patch 21 and patch 22 have the same structural form and are shown in the figure. x The axis is rotationally symmetrical at 180°. The specific construction method will now be explained using the top surface radiating patch 21 as an example. The outline of the top surface radiating patch 21 includes a longer gradient line 211, a shorter gradient line 212, and a radiating groove line 213. In this embodiment, the gradient of the longer gradient line 211 and the shorter gradient line 212 is exponential. Figure 2 The gradual change equations in the coordinate system are as follows: 211→ y =exp(0.0193 x -1.980 212→ y =2.92exp(0.235 x -1.943 The longer gradient line 211 is in x The length of the direction is l a =180 mm, which is in its gradual equation x The variation range is 0~180 mm; the shorter gradient line 212 is in x The length of the direction is l b =10.195 mm, which is the value in its gradual change equation. x The variation range is 0~10.195 mm. In this embodiment, the radial groove line 213 is a cosine-shaped groove line. Figure 2 The equation of the curve in the coordinate system is: 213→ y ={ w / 2-3.526-[exp(0.0193 x )-1.980]}*{abs[cos( πn a ( x -15.195) / 153.831)]-1}+ w / 2 in, w =60 mm is the width of dielectric substrate 4. In the above equation, n a In this embodiment, the number of radial grooves is... n a The value is 20, in the equation x The variation range is 15.195~169.026 mm. The outline of the top surface radiating patch 21 can be obtained according to the above equations, thus constructing a complete top surface radiating patch 21. And... x=0 mm position, i.e., the origin of the coordinate system O At this point, the top surface radiating patch 21 and the bottom surface radiating patch 22 are connected to the parallel double-line transmission line 12, thereby completing the power supply to the radiating structure 2.

[0029] like Figure 1 , Figure 2 , Figure 3 , Figure 4 As shown, the extended ground structure 3 consists of a top-extended extended ground patch 31 and a bottom-extended extended ground patch 32, both of which are used to extend the ground plane 112 of the microstrip transmission line 11. x The direction is extended and expanded. Among them, the top surface extended and expanded patch 31 is located in x Below the axis, on the top surface of the dielectric substrate 4, corresponding to the bottom surface radiating patch 22 of the radiating structure 2, it is electrically connected to the ground plane 112 in the microstrip transmission line 11 through a metal via 33; the bottom surface extended patch 32 is located in x Above the axis, on the bottom surface of the dielectric substrate 4, corresponds to the top surface radiating patch 21 of the radiating structure 2. Since 32 and 112 are both located on the bottom surface of the dielectric substrate 4, they are directly connected without the need for metal vias. 31 and 32 have the same structural form and are related to the figure. x The axis is rotationally symmetrical at 180°. The specific construction method will now be explained using the top-surface extended ground patch 31 as an example. The outline of the top-surface extended ground patch 31 includes an extended ground gradient line 311 and an extended ground groove line 312. In this embodiment, the gradient of 311 is exponential, and 312 is a cosine-shaped groove line. Figure 2 The equations of the curves in the coordinate system are as follows: 311→ y =exp(0.0897 x )-1+ w / 2- w g 312→ y ={ w g -0.715-[exp(0.0897 x )-1]}*{abs[cos( πn b ( x -11.349) / 15.383)]-1}+ w / 2 Extended gradient line 311 in x The length in the direction is l g =26.732 mm, in y Width in the direction is w g =10mm, which is in equation 311x The variation range is 0~26.732 mm; in the extended geodetic trough equation 312... w Where is the width of the dielectric substrate, in the equation x The variation range is 11.349~26.732 mm. The outline of the top surface extension patch 31 can be obtained according to the above equation, thereby constructing a complete top surface extension patch 31. Since 31 and the ground plane 112 in the extended microstrip transmission line 11 are located on the top and bottom surfaces of the dielectric substrate 4, respectively, a metal via 33 is required for electrical connection.

[0030] Using the aforementioned antennas as array elements, construct an E-plane two-element array, such as... Figure 5 , 6 As shown, the edge-to-edge spacing of array elements 5 and 6 along the E-plane direction is... dE =10 mm. To illustrate the effective benefits of the antenna provided by the present invention, two antennas are also given for comparison in this embodiment. The first type is as follows: Figure 7 The first type shown is the unslotted conventional antipodal Vivaldi antenna, also known as the Antipodal Vivaldi Antenna, or simply AVA; the second type is as follows... Figure 8 The slotted antipodal Vivaldi antenna shown is abbreviated as SAVA. The structural dimensions, radiation profile, and feed structure of both types of antennas are consistent with the antenna in this embodiment. Figure 5 , 6 In this manner, two E-plane two-element arrays were constructed using the two antennas used for comparison as array elements, with an edge-to-edge spacing of 10 mm in the E-plane direction. For ease of distinction, the antenna in this embodiment is named Slotted Antipodal Vivaldi Antenna with Extended Ground Structure, or simply SAVA-EGS.

[0031] like Figure 9 , Figure 10 , Figure 11 , Figure 12 As shown, this is a comparison of the radiation characteristics of three E-plane two-element arrays obtained through numerical simulation.

[0032] in Figure 9 This section compares the S11 curves of individual elements in a two-element array. Using S11 < -10 dB as the standard, it can be determined that the lower limit of the bandwidth of a conventional antipodal Vivaldi antenna (AVA) is 3.17 GHz, i.e., the maximum operating wavelength is 94.64 mm. The E-plane width of the AVA can then be calculated. w(60 mm) is approximately 0.63 times the maximum operating wavelength; the lower bandwidth limit of the slotted antipodal Vivaldi antenna (SAVA) is 2.07 GHz, which corresponds to a maximum operating wavelength of 144.93 mm. Calculations show that the E-plane width of the SAVA is... w (60 mm) is approximately 0.41 times the maximum operating wavelength. In comparison, slotting the radiating patch can extend the low-frequency bandwidth of the antenna. The lower limit of the bandwidth of the antenna (SVA-EGS) provided by this invention is 1.61 GHz, that is, the maximum operating wavelength is 186.34 mm. Calculations show that the E-plane width of SAVA-EGS is... w (60 mm) is approximately 0.32 times the maximum operating wavelength. Compared to SAVA, the lower limit of bandwidth has been further extended, and the miniaturization effect is quite significant.

[0033] Furthermore, Figure 10 The S21 curves of three E-plane binary arrays were compared. Within their respective operating frequency bands, the S21 of AVA was below -19.13 dB; the S21 of SAVA was below -18.78 dB; and the S21 of SAVA-EGS was below -15.02 dB. Although the maximum isolation (S21) of SAVA-EGS within its band was worse than the other two antennas, this was due to their different frequency bands. If we use the bandwidth of SAVA-EGS as a basis to interpret the S21 of the other two antennas, we can see that within this frequency band, the maximum S21 of SAVA binary array is -8.96 dB, which is sufficient to demonstrate that the antenna provided by this invention not only extends the lower frequency limit of the bandwidth but also achieves decoupling of the extended low-frequency part; while the maximum S21 of AVA binary array is -17.08 dB, which seems to have lower coupling, but this is actually due to poor radiation performance and weak spatial coupling.

[0034] The table below further quantifies and compares S21 for the three antennas in this embodiment: In addition, by Figure 10 It can be seen that, starting from 2.5 GHz, the isolation of SAVA and the SAVA-EGS of this invention is basically equivalent, indicating that the decoupling effect focuses on the low frequency. For the high frequency part, the isolation is about -30 dB, and no additional decoupling is required. As for AVA, in the frequency range of 2.8~3.5 GHz and 3.7~4.1 GHz, S21 is larger than the other two antennas, that is, the coupling is stronger.

[0035] Figure 11A comparison of the main axis gains of the three antennas shows that, compared to AVA, SAVA and the SAVA-EGS of this invention exhibit significant gains improvements within the relevant frequency band. Compared to SAVA, the SAVA-EGS of this invention also shows a relatively significant gain improvement in the frequency range of 1~2.5 GHz, while the gain of the SAVA-EGS of this invention is essentially equivalent to that of SAVA when the frequency is greater than 2.5 GHz. This demonstrates that the antenna provided by this invention can improve antenna gain within a frequency range close to the lower limit of the operating frequency band.

[0036] Figure 12 A comparison of the front-to-back ratios of the three antennas shows that the front-to-back ratios of SAVA and the SAVA-EGS of this invention are significantly better than those of AVA. Compared to SAVA, the SAVA-EGS of this invention has better front-to-back ratios in the 1~2.5 GHz and 3~4.5 GHz frequency ranges, while at other frequency points, the two are basically equivalent. This indicates that the antenna provided by this invention can further improve the front-to-back ratio and reduce back radiation to a certain extent.

[0037] It is understood that the above embodiments are merely a preferred implementation of the present invention. In practical applications, the gradation method of the extended gradient lines 311 and 321 can also be a linear gradation. For example, an equation can be used. By adjusting the linear slope, the same principle can be achieved: extending the current path and expanding the low-frequency bandwidth.

[0038] The extended trench lines 312 and 322 are not limited to cosine curves. For example, in other embodiments, the extended trench lines 312 and 322 can be constructed as multiple lines along... x A straight line segment extending in the direction. This type of slot structure with straight line segments is simpler and can also disturb and guide the surface current on the extended ground patches 31 and 32, thereby reconstructing the electromagnetic coupling path between array elements and achieving a decoupling effect. These alternative solutions all fall within the scope of protection of this invention.

[0039] This specific embodiment is only used to illustrate the present invention and is not intended to limit the present invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions also fall within the protection scope of the present invention.

Claims

1. A miniaturized self-decoupling ultrawideband Vivaldi antenna, comprising a feeding structure (1), a radiating structure (2), and an extended ground structure (3), characterized in that: The power supply structure (1) is a transition structure that gradually changes from a microstrip transmission line (11) to a parallel double-line transmission line (12). The width of the ground plane (112) of the microstrip transmission line (11) gradually narrows along the length of the conductor (111) to be consistent with the width of the conductor to form a parallel double-line transmission line (12). The radiation structure (2) is a horn-shaped opening structure printed on a dielectric substrate (4), including a top surface radiation patch (21) and a bottom surface radiation patch (22). The top surface radiation patch (21) and the bottom surface radiation patch (22) are 180° rotationally symmetrical about the central axis of the conductor strip (111) in the length direction. The outline of each radiation patch is composed of a gradient line that forms the horn-shaped opening and a radiation groove line (213, 223) opened on the gradient line to improve the surface current distribution. Each radiation patch is connected to a parallel double-line transmission line (12) at the beginning of the gradient line. The extended ground structure (3) is composed of a top extended ground patch (31) and a bottom extended ground patch (32) formed by extending the microstrip transmission line ground plane (112) toward the opening of the radial structure (2). The top extended ground patch (31) and the bottom extended ground patch (32) are 180° rotationally symmetrical about the central axis of the conductor (111) in the length direction. The outline of each extended ground patch is composed of extended ground gradient lines (311, 321) and extended ground groove lines (312, 322). The top extended ground patch (31) is printed on the top surface of the dielectric substrate (4) and is electrically connected to the microstrip transmission line ground plane (112) printed on the bottom surface of the dielectric substrate (4) through a metal via (33) penetrating the dielectric substrate (4). The bottom extended ground patch (32) is printed on the bottom surface of the dielectric substrate (4) and is directly connected to the microstrip transmission line ground plane (112).

2. The miniaturized self-decoupled ultra-wideband Vivaldi antenna according to claim 1, characterized in that, The dielectric substrate (4) in the power supply structure (1), radiation structure (2) and extended ground structure (3) is a single rectangular dielectric plate.

3. The miniaturized self-decoupled ultra-wideband Vivaldi antenna according to claim 1, wherein, The microstrip transmission line ground plane (112) is narrowed by exponential gradual narrowing or elliptical gradual narrowing.

4. The miniaturized self-decoupled ultra-wideband Vivaldi antenna according to claim 1, wherein, The gradient lines of the top surface radiation patch (21) and the bottom surface radiation patch (22) in the radiation structure (2) are exponential gradient lines, linear gradient lines or elliptical curve gradient lines.

5. The miniaturized self-decoupled ultra-wideband Vivaldi antenna according to claim 1, wherein, The radiating grooves (213, 223) in the radiating structure (2) are selected from at least one of parametric periodic curve grooves and periodic geometric grooves.

6. The miniaturized self-decoupling ultrawideband Vivaldi antenna according to claim 1, characterized in that, The extended land structure (3) has extended land gradient lines (311, 321) that are exponential gradient lines, linear gradient lines or elliptical curve gradient lines.

7. The miniaturized self-decoupling ultrawideband Vivaldi antenna according to claim 1, characterized in that, The extended ground trough lines (312, 322) in the extended ground structure (3) are selected from at least one of parametric periodic curve trough lines, periodic geometric trough lines, and straight line segments.

8. The miniaturized self-decoupling ultrawideband Vivaldi antenna according to claim 1, characterized in that, In the extended ground structure (3), the length of the top extended ground patch (31) and the bottom extended ground patch (32) in the direction of the horn-shaped opening does not exceed half the length of the longer gradient line of the top radiating patch (21) and the bottom radiating patch (22) in that direction.

9. The miniaturized self-decoupling ultrawideband Vivaldi antenna according to claim 1, characterized in that, The width of the top surface extension patch (31) and the bottom surface extension patch (32) in the direction perpendicular to the direction of the horn-shaped opening is smaller than the width of the starting end of the gradient line of the radial structure (2) in that direction.

10. The miniaturized self-decoupling ultrawideband Vivaldi antenna according to claim 1 or 7, characterized in that, The number of extension groove lines (312, 322) on the top extension patch (31) and bottom extension patch (32) may be the same as or different from the number of radiation groove lines (213, 223) on the top radiation patch (21) and bottom radiation patch (22).

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