Ultra-wideband omnidirectional Vivaldi antenna array

Abstract

The invention discloses an ultra-wideband omnidirectional Vivaldi antenna array and a feed power divider thereof, and belongs to the technical field of antennas. The antenna array comprises a ground plane, an F4B dielectric plate, a feed network and twelve Vivaldi antenna units which are annularly arranged in a central symmetry mode, each antenna unit comprises a gradually-changed open slot and a three-ellipse combined resonant cavity, and the curve change rate r of an edge arc line of the gradually-changed open slot is optimized to be 0.13; the feed power divider is of a one-to-twelve-path equal-amplitude in-phase structure and is formed by combining a one-to-three-path power divider and a one-to-four-path power divider, the narrowest position of a microstrip line is 0.6 mm, and the relative bandwidth is 133.61%. By optimizing the antenna unit structure and the design of the power divider, the omnidirectional radiation bandwidth of 2.0-9.8 GHz is realized under the condition of only using 12 units, the horizontal plane gain fluctuation is less than 0.8 dB, and the transverse size is only 0.43 lambda, so that the problems of narrow bandwidth, large gain fluctuation, difficult processing of the power divider and large size in the prior art are solved, and the antenna is suitable for miniaturized ultra-wideband communication equipment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of antennas, in particular to a super-wideband omnidirectional Vivaldi antenna array and a matching 1 / 12-way equal-amplitude in-phase feeding power divider. The antenna array and the feeding power divider are suitable for various electronic devices such as communication devices and detection devices that have a demand for super-wideband communication and omnidirectional radiation performance and have a high requirement for compactness of the device structure, and can be widely applied to wireless communication systems, radar detection systems, electromagnetic compatibility test devices and other scenarios. BACKGROUND

[0002] As a kind of wideband antenna, Vivaldi antenna has been widely applied in modern wireless communication, radar and electronic countermeasure fields due to its wideband working characteristics, high radiation gain and low profile structure. However, in actual engineering applications, the existing Vivaldi antenna array still has many technical defects to be solved, which are as follows:

[0003] Limited omnidirectional radiation bandwidth: The omnidirectional radiation bandwidth of the existing Vivaldi antenna array is generally narrow, and it is usually difficult to cover the demand of super-wideband communication scenarios (such as 1-10GHz frequency band), and cannot meet the application scenarios of multi-frequency band and wideband signal transmission.

[0004] Poor horizontal plane gain stability: The gain fluctuation amplitude of the antenna in the horizontal plane is large, often exceeding 1dB, which leads to obvious differences in signal transmission quality in different directions, seriously affecting the stability and reliability of the communication link.

[0005] Insufficient performance of matching feeding power divider: In order to realize equal-amplitude in-phase feeding of the antenna array, a multi-port power divider is needed, but the existing power divider has three problems: first, the structure is complex, and multi-stage cascading and complex wiring are usually used, which is difficult to process; second, the relative bandwidth is small, which is difficult to match the super-wideband working demand of the antenna array; third, the width of the microstrip line of some power dividers is too narrow (usually less than 0.3mm), which requires high precision of the processing equipment, and the performance of the power divider is easily attenuated due to processing errors, which greatly increases the production cost.

[0006] Large antenna structure size: In order to expand the omnidirectional radiation bandwidth, the existing technology usually adopts the way of increasing the number of radiation units (such as setting 16 radiation units), which directly leads to a significant increase in the horizontal size of the antenna (usually more than 0.6λ0, λ0 is the wavelength corresponding to the center frequency), which cannot adapt to the installation space demand of small and integrated electronic devices.

[0007] Based on the defects of the prior art, it becomes a key technical problem for those skilled in the art to develop a Vivaldi antenna array with ultra-wideband omnidirectional radiation characteristics, small horizontal plane gain fluctuation, compact structure, and simple processing of supporting power divider. SUMMARY

[0008] The application aims at the technical problems of existing Vivaldi antenna array, such as narrow omnidirectional radiation bandwidth, large horizontal plane gain fluctuation, high processing difficulty of supporting power divider, and excessive antenna transverse size, and provides an ultra-wideband omnidirectional Vivaldi antenna array and a feeding power divider thereof, aiming to achieve the following objectives:

[0009] Expand the omnidirectional radiation bandwidth of the antenna to meet the demand of ultra-wideband communication;

[0010] Reduce the gain fluctuation in the horizontal plane of the antenna to improve the signal transmission stability;

[0011] Simplify the structural design of the feeding power divider to reduce the processing difficulty and manufacturing cost thereof;

[0012] Reduce the transverse size of the antenna array to realize compact structure and meet the installation demand of small-sized devices. Ultra-wideband omnidirectional Vivaldi antenna array structure

[0013] The ultra-wideband omnidirectional Vivaldi antenna array mainly comprises a ground plane, an F4B dielectric plate, a feeding network, and twelve Vivaldi antenna units.

[0014] The F4B dielectric plate is the core support structure of the entire antenna array, and its thickness, dielectric constant and other parameters directly affect the impedance matching and radiation performance of the antenna. The ground plane and the feeding network are made of high-conductivity copper material and are formed on the upper and lower surfaces of the F4B dielectric plate by printing process:

[0015] The ground plane comprises the Vivaldi antenna array and serves as the grounding reference for the antenna radiation, providing a stable grounding environment for the antenna units and ensuring the radiation performance.

[0016] The input end of the feeding network is connected with the output end of the feeding power divider, and the line layout of the feeding network is matched with the position and impedance of the output port of the power divider, for uniformly transmitting the signals distributed by the power divider to each Vivaldi antenna unit to realize equal-amplitude and in-phase feeding.

[0017] The Vivaldi antenna element layout consists of twelve Vivaldi antenna elements arranged in a centrally symmetrical manner around the geometric center of the antenna array, forming a ring structure. This layout ensures that the radiation directions of each antenna element complement each other in the horizontal plane, thereby achieving omnidirectional radiation and ensuring uniform signal coverage in all directions.

[0018] The Vivaldi antenna element structure: Each Vivaldi antenna element is an independent radiating element, and its structure includes a tapered slot, a resonant cavity, a tapered arc, and related performance parameters.

[0019] The gradient slot and resonant cavity: The gradient slot is the core radiation structure of the antenna element, and its shape and size directly determine the radiation bandwidth and impedance characteristics of the element; the end of the gradient slot is connected to a resonant cavity formed by three ellipses connected in sequence. This resonant cavity optimizes the impedance matching performance by adjusting the equivalent impedance of the element, effectively widening the working bandwidth of the antenna, especially the working bandwidth in the low frequency band.

[0020] The gradient arc parameters are as follows: the two sides of the gradient opening slot are formed by gradient arcs, and the geometry of these arcs is defined using the xy coordinate system: one end of the arc is the starting point A, and the other end is the ending point B. The rate of change r is a key parameter describing the curvature of the arc. The shape of the gradient arc directly affects the current distribution of the antenna element, thus determining the antenna's radiation characteristics and impedance bandwidth.

[0021] Parameter optimization design: Through simulation analysis and experimental verification, the influence of each parameter of the antenna element on performance was clarified, and parameter optimization was completed.

[0022] The impedance bandwidth of an antenna element is mainly related to the overall length, width, and shape of the tapered slot. The low-frequency cutoff frequency is mainly determined by the opening width at the end of the tapered slot. The curve change rate r has little impact on the low-frequency cutoff frequency and will not change the overall impedance bandwidth range of the antenna. Therefore, r can be finally optimized after the core parameters such as the element length, width, and opening width at the end of the slot are determined.

[0023] With a fixed number of twelve antenna elements and parameters such as element length, width, and slot end opening width determined, the curve change rate *r* has a significant impact on the gain fluctuation of the antenna in the horizontal plane: when *r* is small, the gain fluctuation of the antenna in the high-frequency band is small, and under other unchanged conditions, the smaller the value of *r*, the smaller the gain fluctuation amplitude in the horizontal direction and the wider the omnidirectional radiation bandwidth; however, when *r* is too small (e.g., less than 0.1), it will cause impedance mismatch problems (reflection coefficient greater than -10dB) in the mid-frequency band (3-5GHz); when *r* is too large (e.g., greater than 0.15), although it can extend the impedance bandwidth to a certain extent, it will significantly increase the gain fluctuation in the horizontal direction (fluctuation exceeding 1dB in the high-frequency band).

[0024] Considering both impedance matching performance and omnidirectional radiation performance, the optimal value for the curve change rate r is determined to be 0.13. At this value, the antenna can simultaneously meet the requirements of impedance bandwidth and omnidirectional radiation bandwidth, and the horizontal gain fluctuation is minimized.

[0025] The 1-to-12 equal-amplitude, in-phase power divider is used to provide equal-amplitude, in-phase feed signals to the Vivaldi antenna array, and is implemented using a microstrip line structure.

[0026] The power divider consists of one input port (Port 1) and twelve output ports (Port 2, Port 3, Port 4, Port 5, and Port 6; the remaining six output ports are not individually labeled and are collectively referred to as "the remaining output ports"). Each of the twelve output ports corresponds to one of the twelve Vivaldi antenna elements. After the signal is input through Port 1, it is processed by the power divider's internal power distribution structure, enabling the synchronous output of power signals with consistent amplitude and phase across all twelve output ports, ensuring the omnidirectional radiation performance of the antenna array.

[0027] The internal power divider structure employs a multi-stage power divider combination structure of "1 to 3 + 1 to 4", including a 1 to 3 power divider and a 1 to 4 power divider:

[0028] The input terminal of the 1-to-3 power divider is connected to input port Port 1. Its function is to evenly divide one input signal into three signals with equal power.

[0029] Each signal, after being distributed by a 1-to-3 power divider, is input to the input of a 1-to-4 power divider. The three signals output from the 1-to-3 power divider are then connected to the three 1-to-4 power dividers respectively.

[0030] Each 1-to-4 power divider divides the input signal into four equally powerful signals. The three 1-to-4 power dividers output a total of twelve signals, corresponding to the twelve output ports of the power divider, thus achieving equal amplitude and in-phase distribution of the input signal to the twelve output ports.

[0031] Key structural parameters

[0032] Through optimized design, the core performance parameters of the power divider have reached industry-leading levels:

[0033] Microstrip line width: The narrowest width of all microstrip lines in the power divider is 0.6mm. This width is much larger than the minimum width of microstrip lines in power dividers of the same type and number of ports (1 to 12 channels) (usually 0.2-0.3mm). This greatly reduces the requirements for microstrip line precision during processing, reduces performance loss caused by processing errors, and makes the power divider easier to process and manufacture.

[0034] Relative bandwidth: The relative bandwidth of the power divider reaches 133.61%, which is at the leading level among microstrip power dividers of the same type and number of ports. It can completely cover the ultra-wideband operating frequency band of the antenna array and provide reliable power supply guarantee for the antenna array to achieve ultra-wideband omnidirectional radiation performance.

[0035] The beneficial effects of this invention are as follows: Compared with the prior art, the ultra-wideband omnidirectional Vivaldi antenna array and its power divider of this invention have the following significant beneficial effects:

[0036] Outstanding ultra-wideband performance

[0037] Thanks to the 133.61% ultra-wide relative bandwidth of the matching power divider, the Vivaldi antenna array of this invention has the largest known operating bandwidth among antenna products of the same type and number of elements (12 elements);

[0038] By rationally designing the slot line dimensions (especially the width of the end of the tapered slot) and the resonant cavity structure (three elliptical combinations) of the Vivaldi antenna elements, an omnidirectional radiation bandwidth similar to that of a traditional 16-element antenna was achieved with only 12 radiating elements. This breaks through the traditional technical limitation that "the number of radiating elements determines the omnidirectional bandwidth," ensuring ultra-wideband performance while reducing the number of elements.

[0039] With small gain fluctuation and high radiation stability, by optimizing the curve change rate r (8) of the Vivaldi antenna element to 0.13, the gain fluctuation amplitude of the antenna horizontal plane is reduced to the maximum extent while ensuring the antenna impedance matching performance (full-band reflection coefficient less than -10dB). Especially in the high-frequency band (8-10GHz), the gain fluctuation is controlled within 0.5dB, which significantly improves the gain stability in the high-frequency band and ensures the reliability and consistency of signal transmission in all directions during omnidirectional radiation.

[0040] With a compact structure and easy integration, the antenna array has a lateral dimension of only 0.43λ0 (λ0 is the free space wavelength corresponding to the antenna center operating frequency, calculated based on the 5GHz center frequency). Compared with similar antennas using 16 elements (the lateral dimension is usually greater than 0.6λ0), the lateral dimension is reduced by more than 28%, making the structure more compact and adaptable to the installation space requirements of miniaturized and integrated electronic devices, thus expanding the application scenarios of the antenna.

[0041] With low processing difficulty and controllable manufacturing costs, the microstrip line of the power divider has a minimum width of 0.6mm, which reduces the precision requirements of processing equipment (such as PCB etching machines) and reduces the scrap rate during processing. At the same time, the power divider adopts a simplified combination structure of "1 to 3 + 1 to 4", which avoids complex multi-level cascade wiring, simplifies the production process, helps to reduce the manufacturing cost of large-scale production, and enhances the market competitiveness of the product. Attached Figure Description

[0042] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0043] Figure 1: Overall structure and breakdown diagram of the ultra-wideband omnidirectional Vivaldi antenna array of the present invention;

[0044] Figure 2: Schematic diagram of the Vivaldi antenna element of the present invention;

[0045] Figure 3: Antenna horizontal plane gain fluctuation curves corresponding to different curve change rates r;

[0046] Figure 4: Antenna impedance matching curves corresponding to different rates of change r;

[0047] Figure 5: Schematic diagram of a 1-to-12 equal amplitude in-phase power divider;

[0048] Figure 6: Simulation test results of power divider ports 1-6; the figure contains two sub-figures:

[0049] In the diagram: 1 - Ground plane, 2 - F4B dielectric substrate, 3 - Feed network, 4 - Vivaldi antenna element, 5 - Gradient opening slot, 6 - Curve start point A, 7 - Curve end point B, 8 - Curve change rate r, 9 - Input port Port 1, 10 - Output port Port 2, 11 - Output port Port 3, 12 - Output port Port 4, 13 - Output port Port 5, 14 - Output port Port 6, 15 - 1-to-3 power divider, 16 - 1-to-4 power divider. Detailed Implementation

[0050] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0051] As shown in the figure, the antenna array parameters are determined and the structure is designed.

[0052] For the selection of dielectric substrate and metal layer parameters, an F4B dielectric substrate 2 with a thickness of 1.6 mm and a dielectric constant of 2.65 and a loss tangent of 0.001 is selected (the low loss characteristic can reduce energy loss during signal transmission). A copper metal layer with a thickness of 0.035 mm is printed on the upper and lower surfaces of the F4B dielectric substrate 2, respectively. The copper metal layer on the lower surface is processed by etching to form the ground plane 1 (i.e., the grounding structure of the Vivaldi antenna array). The copper metal layer on the upper surface is etched to form the feed network 3. The circuit pattern of the feed network 3 is designed according to the position and impedance characteristics of the power divider output terminal to ensure matching with the power divider output port.

[0053] The basic parameters of the Vivaldi antenna element were determined through simulation and experimental verification. The basic parameters of Vivaldi antenna element 4 are as follows:

[0054] Overall unit length: 35mm (based on the wavelength corresponding to the center frequency of 5GHz, to ensure the unit's radiation performance over a wide frequency band);

[0055] Overall unit width: 20mm (to balance unit radiation efficiency and structural compactness);

[0056] Gradient opening slot 5 end opening width: 8mm (determined according to low frequency cutoff frequency requirements to ensure impedance matching in the low frequency band (1.9GHz);

[0057] Resonant cavity parameters: It is composed of three ellipses with major axes of 5mm, 4mm and 3mm and minor axes of 3mm, 2.5mm and 2mm respectively. The center distance between adjacent ellipses is 2mm (the operating bandwidth is widened by adjusting the equivalent impedance).

[0058] Optimization and verification of the curve change rate r8

[0059] Based on the above fundamental parameters, the curve change rate r8 was optimized using HFSS (High Frequency Structure Simulation Software) to simulate the antenna's impedance bandwidth (reflection coefficient S) at r = 0.1, 0.13, 0.15, and 0.2, respectively. 11 The simulation results regarding the horizontal plane gain fluctuation are as follows:

[0060] When r=0.1: the gain fluctuation in the high-frequency band (8-10GHz) is less than 0.5dB, but the reflection coefficient in the mid-frequency band (3-5GHz) is greater than -10dB, indicating a significant impedance mismatch problem;

[0061] When r=0.15: the impedance bandwidth extends to 1.8-10.5GHz, but the gain fluctuation in the high-frequency band (8-10GHz) reaches 1.2dB, resulting in poor stability;

[0062] When r=0.2: the impedance bandwidth is further extended to 1.7-10.8GHz, but the gain fluctuation across the entire frequency band exceeds 1.5dB, which cannot meet the stability requirements of omnidirectional radiation;

[0063] When r=0.13: the impedance bandwidth is 1.9-10.2GHz (the reflection coefficient is less than -10dB across the entire frequency band), and the horizontal gain fluctuation is less than 0.8dB across the entire frequency band (1.9-10.2GHz), with the gain fluctuation in the high-frequency band (8-10GHz) being only 0.5dB, resulting in the best overall performance.

[0064] Based on the above simulation results, the curve change rate r8 was determined to be 0.13, and a gradient arc was drawn according to the curve equation in the xy coordinate system to complete the structural design of a single Vivaldi antenna element 4.

[0065] Overall layout of antenna array

[0066] Twelve Vivaldi antenna elements 4 are printed on the ground plane 1 (the copper layer on the lower surface of the F4B dielectric substrate) using an etching process, and the layout satisfies the following:

[0067] The distance from the center of each antenna element to the geometric center of the antenna array is 25mm;

[0068] The included angle between two adjacent antenna elements is 30° (360° / 12), ensuring that the twelve elements are evenly distributed on the horizontal plane to achieve omnidirectional radiation coverage.

[0069] II. Power Divider Fabrication and Assembly

[0070] Power divider substrate and manufacturing process

[0071] The power divider uses the same F4B dielectric substrate (1.6mm thick, dielectric constant 2.65) as the antenna array. The 1-to-3 power divider 15 and the 1-to-4 power divider 16 are fabricated using microstrip line etching technology. Specific parameters are as follows:

[0072] 1-to-3 power divider 15: The input port impedance is 50Ω (matching the signal source impedance), and the impedance of each of the three output ports is 75Ω; the microstrip line width gradually changes from 2.4mm at the input port (corresponding to 50Ω impedance) to 1.2mm at the output port (corresponding to 75Ω impedance).

[0073] 1-to-4 power divider 16: The input port impedance is 75Ω (matching the output impedance of a 1-to-3 power divider), and the impedance of each of the four output ports is 50Ω (matching the input impedance of the antenna unit); the microstrip line width gradually changes from 1.2mm at the input port to 2.4mm at the output port.

[0074] The minimum width of all microstrip lines is strictly controlled to 0.6 mm to ensure fabrication feasibility.

[0075] Power divider port connection and performance verification

[0076] Connection method: Connect the input port of the 1-to-3 power divider 15 directly to the input port Port 19 of the power divider; connect the three output ports of the 1-to-3 power divider 15 to the input ports of the three 1-to-4 power dividers 16 one by one; the twelve output ports of the three 1-to-4 power dividers 16 (each 1-to-4 power divider outputs four channels) serve as the twelve output ports of the power divider (Port 2-Port 13 and the remaining output ports);

[0077] Performance simulation verification: The amplitude and phase consistency of the power divider were simulated and tested using HFSS software (test results are shown in Figure 6). In the 1.99-10GHz frequency band, the amplitude difference of the twelve output ports was less than 0.3dB and the phase difference was less than 5°, which fully meets the requirements of the antenna array for "equal amplitude and phase feeding".

[0078] Assembly of power divider and antenna array

[0079] The twelve output ports of the power divider are electrically connected to the feed network 3 on the upper surface of the F4B dielectric board 2 through the metallized via technology: the metallized vias penetrate the F4B dielectric board 2, one end is soldered to the output port (microstrip line) of the power divider, and the other end is soldered to the corresponding line of the feed network 3, ensuring that the signal is transmitted stably and with low loss from the power divider to each Vivaldi antenna element 4.

[0080] III. Antenna Array Performance Testing

[0081] The assembled ultra-wideband omnidirectional Vivaldi antenna array was subjected to performance testing in a standard microwave anechoic chamber. The test results are as follows:

[0082] Working bandwidth test

[0083] Impedance bandwidth: Within the 1.9-10.2GHz frequency band, the voltage standing wave ratio (VSWR) of the antenna is less than 2, which meets the industry standard requirements for impedance matching (VSWR≤2) of wireless communication equipment;

[0084] Omnidirectional radiation bandwidth: In the 2.0-9.8GHz frequency band, the non-circularity of the horizontal radiation pattern of the antenna (the difference between the maximum gain and the minimum gain) is less than 2dB, which meets the performance index of an omnidirectional radiation antenna. Moreover, this bandwidth range is similar to the omnidirectional radiation bandwidth (1.9-10.0GHz) of a 16-element antenna of the same type, which verifies the ultra-wideband omnidirectional radiation capability of the present invention under the premise of reducing the number of elements.

[0085] Gain characteristics were tested within the 2.0-9.8 GHz omnidirectional radiation bandwidth. The gain range of the antenna horizontal plane was 3-5 dBi, and the gain fluctuation across the entire frequency band was less than 0.8 dB. In particular, in the 8-9.8 GHz high-frequency band, the gain fluctuation was only 0.5 dB, which is significantly better than existing technologies (the fluctuation in the high-frequency band is usually greater than 1 dB), proving that the antenna has excellent gain stability.

[0086] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, the phrase "comprising an element defined as..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0087] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An ultra-wideband omnidirectional Vivaldi antenna array, characterized in that: It includes a ground plane (1), an F4B dielectric substrate (2), a feed network (3), and twelve Vivaldi antenna elements (4); the ground plane (1) and the feed network (3) are both made of copper and are formed on the upper and lower surfaces of the F4B dielectric substrate (2) by printing process. The ground plane (1) is composed of a Vivaldi antenna array, and the twelve Vivaldi antenna elements (4) are arranged in a circular manner around the center of the array with the geometric center of the antenna array as the symmetry point.

2. The ultra-wideband omnidirectional Vivaldi antenna array according to claim 1, characterized in that: The Vivaldi antenna unit (4) is provided with a gradient opening slot (5). The end of the gradient opening slot (5) is connected to a resonant cavity formed by three ellipses connected in sequence. The two sides of the gradient opening slot (5) are gradient arcs. One end of the gradient arc is the curve starting point A (6), and the other end is the curve ending point B (7). The curve change rate is r (8), and the value of r (8) is 0.

13.

3. The ultra-wideband omnidirectional Vivaldi antenna array according to claim 2, characterized in that: The Vivaldi antenna unit (4) has an overall length of 35mm and an overall width of 20mm; the opening width at the end of the gradient opening slot (5) is 8mm; among the three ellipses constituting the resonant cavity, the major axis of the first ellipse is 5mm and the minor axis is 3mm, the major axis of the second ellipse is 4mm and the minor axis is 2.5mm, the major axis of the third ellipse is 3mm and the minor axis is 2mm, and the center distance between two adjacent ellipses is 2mm.

4. The ultra-wideband omnidirectional Vivaldi antenna array according to claim 1, characterized in that: The F4B dielectric substrate (2) has a thickness of 1.6 mm, a dielectric constant of 2.65, and a loss tangent of 0.001; the copper layer of the ground plane (1) and the feed network (3) has a thickness of 0.035 mm; the distance from the center of the twelve Vivaldi antenna elements (4) to the geometric center of the antenna array is 25 mm, and the angle between two adjacent elements is 30°.

5. The ultra-wideband omnidirectional Vivaldi antenna array according to claim 1, characterized in that: The antenna array has a lateral dimension of 0.43λ0. In the 1.9-10.2GHz frequency band, the voltage standing wave ratio (VSWR) of the antenna is less than 2; in the 2.0-9.8GHz frequency band, the non-circularity of the horizontal radiation pattern of the antenna is less than 2dB, and the horizontal gain fluctuation is less than 0.8dB.

6. A 1-to-12 equal-amplitude, in-phase power divider for an ultra-wideband omnidirectional Vivaldi antenna array according to any one of claims 1-5, characterized in that: It is implemented in the form of a microstrip line structure, including one input port Port 1 (9) and twelve output ports. The twelve output ports are connected one-to-one with twelve Vivaldi antenna elements (4). The power divider is composed of a 1-to-3 power divider (15) and three 1-to-4 power dividers (16). The input signal is divided into three paths by the 1-to-3 power divider (15), and each signal is input to a 1-to-4 power divider (16) and divided into four paths. Finally, the power signals with equal amplitude and in phase are output through the twelve output ports.

7. The 1-to-12 equal-amplitude, in-phase power divider according to claim 6, characterized in that: The power divider is based on an F4B dielectric substrate with a thickness of 1.6 mm and a dielectric constant of 2.

65. The input port impedance of the 1-to-3 power divider (15) is 50 Ω, the output port impedance is 75 Ω, and the microstrip line width gradually changes from 2.4 mm at the input port to 1.2 mm at the output port. The input port impedance of the 1-to-4 power divider (16) is 75 Ω, the output port impedance is 50 Ω, and the microstrip line width gradually changes from 1.2 mm at the input port to 2.4 mm at the output port.

8. The 1-to-12 equal-amplitude, in-phase power divider according to claim 6, characterized in that: The narrowest width of all microstrip lines in the power divider is 0.6mm; the relative bandwidth of the power divider is 133.61%; in the 1.99-10GHz frequency band, the amplitude difference of the twelve output ports is less than 0.3dB, and the phase difference is less than 5 degrees.

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