A cross-dipole broadband antenna

Abstract

The present invention discloses a cross-dipole broadband antenna, which belongs to the field of wireless communications. The antenna has dual-polarization characteristics and can simultaneously support two mutually perpendicular polarization directions. The high isolation and optimized design of the dual-polarization antenna reduce signal attenuation and loss, ensuring the reliability and stability of the communication system. In addition, the antenna has a balun structure, which can effectively cut off the high-frequency current flowing from the cross-dipole patch through the outer sheath of the cable shielding layer, ensuring correct signal transmission and good antenna performance. The balun structure can realize conversion between different impedances, so that the impedance between the antenna and the transmission line is matched, thereby ensuring maximum power transmission. In addition, the patch of the antenna adopts a new fractal structure, namely a quarter-circle fractal structure, which is conducive to improving antenna performance, achieving lightweight while maintaining broadband characteristics, increasing bandwidth, and optimizing radiation efficiency.

Description

Technical Field

[0001] The present invention belongs to the field of wireless communications, and more particularly, relates to a cross-dipole broadband antenna. Background Art

[0002] Compared with other types of antennas, cross-dipole antennas are very popular in modern wireless communication systems and are one of the important choices for broadband antenna design. The reasons are as follows: (1) Cross-dipole antenna design can provide a wider operating bandwidth, which is very important for wireless communication systems that need to cover multiple frequency bands. (2) Cross-dipole antenna design helps to achieve miniaturization of antennas, save space and weight, and reduce costs. (3) Cross-dipole antennas can achieve dual polarization through design, further improving the signal-to-noise ratio and anti-interference characteristics of the communication system. (4) Cross-dipole antennas have a simple structure and are easy to implement and integrate into the system. At the same time, the feeding method is convenient, which helps to simplify the installation and maintenance of the antenna. (5) Cross-dipole antennas can achieve directional radiation, which is very useful for applications that require signal transmission in a specific direction. (6) Cross-dipole antennas can achieve filtering functions by loading specific structures, improving impedance bandwidth and axial ratio bandwidth. However, since cross-dipole antennas are composed of multiple dipoles, there may be electromagnetic coupling between them. This coupling may cause interference between antennas and performance degradation. In addition, in order to achieve better performance, cross-dipole antennas may require complex structural design and sophisticated processing technology. For example, for some dual-polarized or multi-polarized cross-dipole antennas, it is necessary to precisely control parameters such as the size, shape, position, and direction of each dipole, which places high demands on processing and manufacturing precision, increasing production costs and difficulty. Summary of the Invention

[0003] In response to the above defects or improvement needs of the prior art, the present invention provides a cross-dipole broadband antenna, thereby solving the problems of interference between antennas due to electromagnetic coupling and complex structural design in the existing cross-dipole antenna.

[0004] To achieve the above object, according to a first aspect of the present invention, there is provided a cross-dipole broadband antenna, comprising: a substrate, a balun structure, a cross-dipole patch, a metal reflector, and two coaxial cables;

[0005] The cross-dipole patch includes a first dipole patch unit and a second dipole patch unit, and the first dipole patch unit and the second dipole patch unit each include two metal sheets, the two metal sheets of the first dipole patch unit and the second dipole patch unit are respectively connected to each other by a first metal strip and a second metal strip, the first dipole patch unit and the second dipole patch unit are cross-placed on the substrate, and the first metal strip and the second metal strip are perpendicular to each other, so that the first dipole patch unit and the second dipole patch unit are rotationally symmetrically distributed on the substrate; wherein the shape of the metal sheet is a splicing of a three-quarter circle sector consisting of two straight line segments and an arc segment and a square, and two adjacent sides of the square completely coincide with the two straight line segments, and the sector area of ​​the metal sheet has three circular hollow openings, which are respectively located in each sub-area after the sector area is divided into three equal parts, with the midpoint of the bisector of each sub-area as the center and half of the radius of the three-quarter circle as the diameter;

[0006] The balun structure includes a base plate and two conductive pillars; wherein the base plate is placed above the metal reflector, one end of the two conductive pillars is respectively connected to one side of the base plate, and the other end is respectively connected to the first and second dipole patch units;

[0007] One end of the two coaxial cables is connected to the bottom plate respectively, and the other end is connected to the first and second dipole patch units respectively.

[0008] According to a second aspect of the present invention, a drone system is provided, comprising a drone and the cross-dipole broadband antenna as described in the first aspect.

[0009] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0010] The cross-dipole broadband antenna provided by the present invention has dual-polarization characteristics and can simultaneously support two mutually perpendicular polarization directions. The high isolation and optimized design of the dual-polarization antenna reduce signal attenuation and loss, ensuring the reliability and stability of the communication system. In addition, the cross-dipole antenna designed by the present invention has a balun structure, which can effectively cut off the high-frequency current flowing from the cross-dipole patch through the outer skin of the cable shielding layer, ensuring the correct transmission of the signal and good antenna performance. In addition, the balun structure can realize the conversion between different impedances, so that the impedance between the antenna and the transmission line is matched, thereby ensuring maximum power transmission. In addition, the patch of the present invention adopts a new fractal structure, namely a quarter-circle fractal structure, which is conducive to improving the performance of the antenna, achieving lightweight while maintaining broadband characteristics, increasing bandwidth, and optimizing radiation efficiency. Due to the self-similarity of the fractal, the fractal antenna maintains the similarity of electrical properties at different scales, thereby achieving multi-band working characteristics. The fractal structure enables the antenna size to be reduced. By introducing the fractal structure, the electrical length of the antenna can be effectively increased without physically increasing the actual size of the antenna. This means that the physical size of the antenna can be significantly reduced while maintaining the same antenna performance; the design of the fractal antenna allows for more efficient energy coupling and radiation, helping to improve the overall performance and efficiency of the antenna.

[0011] The cross-dipole broadband antenna provided by the present invention is applied to the working scene of a drone as an example for simulation. The simulation results show that the cross-dipole antenna provided by the present invention covers the frequency band of 1.81GHz to 2.81GHz in the -15dB impedance bandwidth, and the port isolation in the frequency band range of 1.50GHz to 2.81GHz is greater than 25dB. The antenna 3D radiation pattern shows that the maximum gain is 7.98dB and has good radiation characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a schematic diagram of a broadband cross-dipole antenna provided by an embodiment of the present invention.

[0013] Figure 2 This is a second schematic diagram of a broadband cross-dipole antenna provided by an embodiment of the present invention.

[0014] Figure 3 A schematic diagram of a fractal structure of a quartered circle provided by an embodiment of the present invention.

[0015] Figure 4 A schematic diagram of the patch shape provided by an embodiment of the present invention.

[0016] Figure 5 Schematic diagram comparing the first-order Sierpinski-like fractal structure and the quarter-circle fractal structure of the broadband cross-dipole antenna provided by an embodiment of the present invention.

[0017] Figure 6 This is a diagram of the simulation results of the input reflection coefficient S11 corresponding to the first-order Sierpinski-like fractal structure and the quarter-circle fractal structure of the cross-dipole antenna provided in an embodiment of the present invention.

[0018] Figure 7 This is a simulation result diagram of the forward transmission coefficient S21 corresponding to the first-order Sierpinski-like fractal structure and the quarter-circle of the cross-dipole antenna provided in an embodiment of the present invention.

[0019] Figure 8 This is a comparison diagram of return loss simulation of a broadband cross dipole antenna with a balun structure and a broadband cross dipole antenna without a balun structure provided by an embodiment of the present invention.

[0020] Figure 9 This is a comparison diagram of port isolation simulation of a broadband cross dipole antenna with a balun structure and a broadband cross dipole antenna without a balun structure provided by an embodiment of the present invention.

[0021] Figure 10 This is a diagram of the EH plane simulation results of the broadband cross-dipole antenna provided by an embodiment of the present invention when a balun structure is attached.

[0022] Figure 11 This is a diagram of the EH plane simulation results of the broadband cross-dipole antenna provided by an embodiment of the present invention without a balun structure.

[0023] Figure 12 This is a diagram showing the simulation results of the 3D directional pattern of a broadband cross-dipole with a balun structure provided in an embodiment of the present invention.

[0024] Figure 13 This is a diagram showing the simulation results of the broadband cross-dipole 3D pattern without a balun structure provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0025] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0026] The embodiment of the present invention provides a cross-dipole broadband antenna, such as Figure 1-2 As shown, it includes: a substrate 1, a balun structure 2, a cross-dipole patch 3, a metal reflector 4 and two coaxial cables 51 and 52;

[0027] The cross-dipole patch includes a first dipole patch unit and a second dipole patch unit, and the first and second dipole patch units each include two metal pieces of exactly the same shape and size, the two specific metal pieces of the first dipole patch unit are connected to each other by a first metal strip, and the two specific metal pieces of the second dipole patch unit are connected to each other by a second metal strip, the first and second dipole patch units are placed crosswise on the substrate, the intersection coincides with the center point of the substrate, and the first and second metal strips are perpendicular to each other, so that the first and second dipole patch units are rotationally symmetrically distributed on the substrate; wherein the shape of the metal piece is a three-quarter circle sector composed of two straight line segments and an arc segment and a square, and the two adjacent sides of the square completely coincide with the two straight line segments, that is, as Figure 4 As shown, the side length r1 of the square is equal to the length d1 / 2 of the straight line segment; the sector area of ​​the metal sheet has three circular hollow openings, which are respectively located in each sub-area after the sector area is divided into three equal parts, with the average dividing line of each sub-area (such as Figure 4 As shown, the dividing line is the line that divides the sub-area into two areas equally, with the midpoint of the radius of the three-quarter circle as the center and half of the radius of the three-quarter circle as the diameter, that is, d2=d1 / 2;

[0028] The balun structure includes a base plate and two conductive pillars; wherein the base plate is placed above the metal reflector, and one end of the two conductive pillars is respectively connected to one side of the base plate, and the other end is respectively connected to the first and second dipole patch units;

[0029] One end of the two coaxial cables is connected to the bottom plate respectively, and the other end is connected to the first and second dipole patch units respectively.

[0030] like Figure 3 As shown in (a) and (b) in the figure, the fractal structure of the patch proposed in the example of the present invention is a quarter-circle fractal structure. On the basis of the original circular antenna patch, two mutually perpendicular diameters are made, and the two diameters are divided into four equal parts. The centers of the four small circles are located at the one-quarter and three-quarter points of the two diameters. The diameter of the small circle is one-fourth of the large circle. The four small circles on each patch are dug out to form a quarter-circle fractal structure. Due to the influence of the position of the ideal conductor and the balun, each oscillator (i.e., patch) will only dug out the three small circles farther away from the center point of the substrate.

[0031] Preferably, the connection portions between one end of the two conductive pillars and one side of the base plate are both rounded.

[0032] Preferably, the two coaxial cables each include an inner conductor and an outer conductor, which are respectively connected to the two metal sheets of the first and second dipole patch units in a one-to-one correspondence.

[0033] The antenna provided by an embodiment of the present invention is fed by two coaxial cables, each coaxial cable is connected to a pair of dipoles (i.e., the first dipole patch unit or the second dipole patch unit), wherein the inner conductor and the outer conductor are each connected to a dipole, that is, the inner conductor and the outer conductor are respectively connected to a pair of dipoles in a one-to-one correspondence.

[0034] Preferably, the lengths of the two conductive pillars are each one-quarter of the length of the transmission line.

[0035] Preferably, vertical metal plates are arranged around the metal reflective plate.

[0036] The metal reflector can effectively reflect the signal emitted by the vibrator, enhance the radiation intensity of the antenna in a specific direction, and improve the signal's directionality and coverage range.

[0037] Preferably, the substrate is made of glass_PTFEreinf material.

[0038] The thickness and dielectric constant of the substrate are set according to the operating frequency band of the antenna and can be obtained using the simulation software HFSS.

[0039] A balun, short for balanced-to-unbalanced converter, is an electronic device used to convert balanced signals (such as differential signals) into unbalanced signals (such as single-ended signals). Baluns are crucial in antenna design. They not only solve the problem of converting balanced and unbalanced signals but also improve antenna performance and the stability of wireless communication systems through functions such as impedance matching and common-mode rejection.

[0040] The cross-dipole broadband antenna provided in the embodiment of the present invention can effectively cut off the high-frequency current flowing from the cross-dipole patch through the outer skin of the cable shielding layer through the balun structure, ensuring the correct transmission of the signal and good antenna performance; the patch fractal structure adopted can effectively increase the electrical length of the antenna without physically increasing the actual size of the antenna. This means that the physical size of the antenna can be significantly reduced while maintaining the antenna performance unchanged; the designed antenna has the characteristics of dual polarization and miniaturization, and is suitable for a variety of communication scenarios, especially communication scenarios that require lightweight and miniaturized antennas, such as drones. Based on this, an embodiment of the present invention provides a drone system, including a drone and a cross-dipole broadband antenna as described in any of the above embodiments.

[0041] The following is a comparative analysis of the performance of the cross-dipole broadband antenna provided by the embodiment of the present invention and the antenna after the antenna patch is optimized using a first-order Sierpinski-like fractal structure.

[0042] like Figure 5 As shown in (a) and (b) in the figure, the classic Sierpinski carpet is a square. The square is divided into 9 equal parts and the middle part is dug out to obtain a first-order Sierpinski fractal structure. Similarly, a similar operation is performed on the circular patch in the example of the present invention. The circle in the center of the patch is dug out to obtain a first-order Sierpinski fractal structure, as shown in Figure 5 As shown in (a); the schematic diagram of the application of the quarter-circle fractal structure proposed in the embodiment of the present invention to the antenna patch is shown in Figure 5 As shown in (b) of FIG. It is understood that, to facilitate the connection between the two patches of the first dipole patch unit / the second dipole patch unit, the square edge area of ​​the patch can be cut away. The cross-dipole broadband antenna provided in this embodiment of the present invention uses a glass-PTFE reinforcing material with a thickness of 1 mm and a relative dielectric constant of 2.5.

[0043] S-parameters, or scattering parameters, are complex values ​​that describe the reflection and transmission characteristics of electromagnetic waves in RF devices, such as antennas, at specific frequencies. They are one of the criteria for judging antenna performance and are extremely important in RF and microwave engineering. These parameters not only provide detailed information about antenna reflection and transmission characteristics but also help engineers design and optimize antenna structures for optimal communication performance.

[0044] For antennas, S parameters primarily include S11 (input reflection coefficient), S21 (forward transmission coefficient), S12 (reverse transmission coefficient), and S22 (output reflection coefficient). Since the two ports in this example are symmetrical, only S11 and S21 are considered in the S parameters to characterize antenna performance.

[0045] The S11 parameter reflects the antenna's return loss, that is, how much energy is reflected by the antenna instead of being effectively radiated. Ideally, the S11 value should be as low as possible, indicating that most of the energy is successfully radiated rather than reflected back.

[0046] Define return loss RL and input reflection coefficient S 11 , where Γ is the port reflection coefficient

[0047] S11=201gΓ

[0048] RL=-S11

[0049] The S21 parameter describes the gain or loss of a signal when it passes through an antenna, which is crucial for determining the transmission efficiency of the antenna.

[0050] When an antenna has two or more feed ports, the mutual coupling between the ports needs to be considered, which is generally characterized by port isolation (Iso). This can be calculated using S parameters:

[0051] Iso=-20log|S21|

[0052] The general requirement for antenna port isolation is at least greater than 25dB.

[0053] Comparison of the input reflection coefficient S11 simulation results of the cross-dipole broadband antenna provided by the embodiment of the present invention and the one using the first-order Sierpinski fractal structure Figure 6 As shown, the two curves show a high degree of consistency in overall trend and direction, with only slight differences between the two curves. The S11 value of the first-order Sierpinski-like fractal structure reaches its lowest point at 1.92GHz, while the S11 value of the quarter-circle fractal structure reaches its lowest point at 1.94GHz. The resonance point of the quarter-circle fractal structure is closer to the preset antenna operating frequency of 2GHz. In addition, the overall S11 value of the quarter-circle fractal structure is lower than that of the first-order Sierpinski-like fractal structure. This indicates that the use of the quarter-circle fractal structure improves the antenna impedance matching, allowing more energy to be radiated rather than reflected, thereby improving the antenna's radiation efficiency.

[0054] The simulation results of the forward transmission coefficient S21 of the cross-dipole broadband antenna provided by the embodiment of the present invention and the first-order Sierpinski fractal structure are as follows: Figure 7 As shown in the figure, the S21 curve change trends and concavity of the quarter-circle fractal structure and the first-order S-fractal structure mentioned in the present invention are almost the same, and the numerical values ​​are also obviously homogeneous. The two curves first decrease and then increase, and the two-port isolation of the two fractal structures is greater than 25dB in the frequency band of 1.5GHz to 2.80GHz, and the influence of mutual coupling between ports is weak. However, in the frequency band of 1.93GHz to 2.64GHz, the S21 curve value under the quarter-circle fractal structure is slightly lower than that of the first-order S-fractal structure, showing the slight superiority of the quarter-circle in the port isolation indicator.

[0055] In order to explore the influence of balun on antenna performance, the broadband cross-dipole antenna with and without balun structure were simulated respectively.

[0056] A balun, a balanced-to-unbalanced converter, is primarily used to convert and match balanced and unbalanced circuits. It ensures equal signal amplitudes and opposite phases at the antenna's two feed points, optimizing antenna performance. The balun's design adjusts the impedance ratio between the unbalanced and balanced ends, maximizing the signal source's output power transmitted to the antenna and improving overall system efficiency.

[0057] A balun can effectively improve antenna performance by eliminating the adverse effects of unbalanced feed on antenna radiation. By eliminating imbalance, it reduces radiation loss, improves the directivity pattern, and corrects the direction of maximum radiation. A balun can also address the mismatch between the antenna input impedance and the feeder characteristic impedance.

[0058] The return loss simulation comparison of the broadband cross dipole antenna provided by the embodiment of the present invention with a balun structure and the broadband cross dipole antenna without a balun structure is shown in FIG. Figure 8 As shown in the figure, the -15dB impedance bandwidth of the cross-dipole antenna without a balun structure covers 1.77GHz to 2.80GHz, and the lowest point of return loss is around -24dB; the -15dB impedance bandwidth of the cross-dipole antenna with a balun structure covers 1.81GHz to 2.80GHz, and the lowest point of return loss is around -44dB; there is no obvious change in the impedance bandwidth of the two; the S11 curve shows an overall downward trend after adding the balun structure, and the return loss values ​​of the first resonance point and the second resonance point both decrease, which means that the balun improves the impedance matching between the antenna and the feeder, that is, the energy reflected back to the source end is reduced, the energy lost by the antenna system is reduced, and the energy transmission efficiency is high, which meets the requirements of wide beam communication of drone antennas.

[0059] The port isolation simulation comparison of the broadband cross dipole antenna provided by the embodiment of the present invention with a balun structure and the broadband cross dipole antenna without a balun structure is shown in FIG. Figure 9 As shown in the figure, without the balun structure, the bandwidth where the two-port isolation S21 is less than -25dB covers the frequency range of 1.71GHz to 2.80GHz, with a minimum of -27.4dB. With the balun structure, the two-port isolation coverage bandwidth is expanded and the minimum point is located at -32.4dB. This means that the balun structure reduces the interference between ports 1 and 2, further reducing the mutual coupling between ports 1 and 2. In addition, the energy loss transmitted from port 1 to port 2 is reduced, indicating that the balun structure has improved transmission efficiency.

[0060] An antenna's radiation pattern is a three-dimensional image that depicts the field or power (proportional to the square of the field) as a function of the spherical coordinates θ and φ. It represents the antenna's ability to receive and transmit electromagnetic waves in space. It can be represented by a cross-section along the axis containing the main lobe. The main beam (main lobe) of the radiation pattern radiates along the z-axis, the direction of maximum radiation. The other lobes are called side lobes (or back lobes). Smaller side lobes indicate more concentrated antenna radiated power. Larger side lobes indicate greater backward radiation, which weakens the radiation in the direction of the main lobe and results in a loss of antenna gain.

[0061] Half-power beamwidth, also known as 3dB beamwidth, is the angle between two points with half-power level values ​​in the power pattern when the power is half of the maximum value. The formula is:

[0062] HPBW=|θ left -θ right |θleft;

[0063] Represents the angle of the left point at 0.5 in the power pattern. right Represents the angle of the right point at 0.5 in the normalized power pattern

[0064] HPBW is an important indicator of the antenna's directivity. A smaller HPBW value means more concentrated antenna energy.

[0065] Antenna patterns are divided into E-plane patterns and H-plane patterns. The E-plane is the plane where the electric lines of force lie, while the H-plane is the plane where the magnetic lines of force lie. The EH-plane pattern demonstrates the radiation characteristics and pattern of the antenna.

[0066] The EH surface simulation results of the broadband cross dipole antenna provided by the embodiment of the present invention with a balun structure are as follows: Figure 10 As shown in the figure, the antenna pattern with the balun structure shows good symmetry; the half-power beamwidth of the E-plane and H-plane at the center frequency of 2GHz are both 72°, and the radiation range is wide.

[0067] The EH surface simulation results of the broadband cross dipole antenna without balun structure provided by the embodiment of the present invention are as follows: Figure 11 As shown in the figure, the half-power beamwidth of both the E-plane and H-plane at a center frequency of 2 GHz is 68°, which reduces the radiation range compared to the broadband cross-dipole antenna with a balun structure. The sidelobes of the antenna pattern without a balun structure shift to the left, and a new sidelobe appears at theta equal to 120°.

[0068] A 3D pattern graphically displays the radiation intensity of an antenna at different spatial angles. This pattern is typically based on a spherical coordinate system, with the antenna at the center and the surrounding sphere representing the radiation intensity at different angles. 3D patterns are crucial for evaluating and optimizing antenna performance because they provide a comprehensive view of how the antenna radiates energy in all directions.

[0069] The radiation pattern is a rough, qualitative description of an antenna's directivity. Other metrics provide a more precise, quantitative description of an antenna: directivity coefficient and gain. These coefficients make it easy to compare the energy concentration of different antennas.

[0070] The directivity coefficient is defined as the ratio of the maximum radiated power density of the antenna to the average radiated power density of the entire antenna at a solid angle of 4π. The resulting value is the directivity coefficient. The formula is as follows:

[0071]

[0072] Where S max is the maximum radiation power density, P r is the total radiated power of the antenna.

[0073] If the antennas have the same input power, the ratio of the target antenna's radiation in the direction of maximum radiation to that of an isotropic antenna is the power multiplier, which is the directivity coefficient. An omnidirectional antenna has a directivity coefficient of 1, meaning it has no directionality. However, conventional antennas are directional, and their directivity coefficients are generally greater than 1.

[0074] From the perspective of describing the degree of antenna energy concentration, antenna gain and antenna directivity are similar properties. However, there is a slight difference between the two. The comparison benchmark for gain is the total input energy of the antenna.

[0075] Therefore, the antenna's gain coefficient is calculated by comparing the antenna's maximum radiated power density with the average input power across a 4π solid angle. Therefore, the directivity coefficient and gain must be multiplied by the radiation efficiency η. If the antenna achieves 100% radiation efficiency—radiating all net input energy—then the antenna's gain is equal to the directivity coefficient. If the antenna's radiation efficiency is less than 100%, the gain is less than the directivity coefficient.

[0076] The radiation efficiency η is the antenna's radiated power divided by the antenna's net input power. Here, Pin is the antenna's net input power from the RF front end.

[0077]

[0078] So the gain of the antenna is

[0079]

[0080] The gain reflects that for the antenna, not all the net input energy received from the front end is radiated, but some energy is lost in the antenna.

[0081] The simulation results of the broadband cross-dipole 3D pattern with a balun structure provided by the embodiment of the present invention are as follows: Figure 12 As shown, the simulation results of the broadband cross-dipole 3D pattern without balun structure provided by the embodiment of the present invention are as follows Figure 13 , Figure 12 and Figure 13 By comparison, it can be seen that the balun structure does not have a significant impact on the radiation and gain of the antenna. Without the balun structure, the gain of the broadband cross dipole only drops from 7.98dB to 7.93dB.

[0082] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A cross-dipole broadband antenna, characterized in that: include: Substrate, balun structure, cross-dipole patch, metal reflector and two coaxial cables; The cross-dipole patch includes a first dipole patch unit and a second dipole patch unit, and the first dipole patch unit and the second dipole patch unit each include two metal sheets, the two metal sheets of the first dipole patch unit and the second dipole patch unit are respectively connected to each other by a first metal strip and a second metal strip, the first dipole patch unit and the second dipole patch unit are cross-placed on the substrate, and the first metal strip and the second metal strip are perpendicular to each other, so that the first dipole patch unit and the second dipole patch unit are rotationally symmetrically distributed on the substrate; wherein the shape of the metal sheet is a splicing of a three-quarter circle sector consisting of two straight line segments and an arc segment and a square, and two adjacent sides of the square completely coincide with the two straight line segments, and the sector area of ​​the metal sheet has three circular hollow openings, which are respectively located in each sub-area after the sector area is divided into three equal parts, with the midpoint of the bisector of each sub-area as the center and half of the radius of the three-quarter circle as the diameter; The balun structure includes a base plate and two conductive pillars; wherein the base plate is placed above the metal reflector, one end of the two conductive pillars is respectively connected to one side of the base plate, and the other end is respectively connected to the first and second dipole patch units; One end of the two coaxial cables is connected to the bottom plate respectively, and the other end is connected to the first and second dipole patch units respectively.

2. The cross-dipole broadband antenna according to claim 1, wherein: The connection parts between one end of the two conductive pillars and one side of the bottom plate are both rounded.

3. The cross-dipole broadband antenna according to claim 1, wherein: The two coaxial cables each include an inner conductor and an outer conductor, which are respectively connected to the two metal sheets of the first and second dipole patch units in a one-to-one correspondence.

4. The cross-dipole broadband antenna according to claim 1, wherein: The lengths of the two conductive pillars are each one-quarter of the length of the transmission line.

5. The cross-dipole broadband antenna according to claim 1, wherein: Vertical metal plates are arranged around the metal reflector.

6. The cross-dipole broadband antenna according to claim 1, wherein: The substrate is made of glass_PTFEreinf material.

7. A drone system, characterized in that: The invention comprises a drone and the cross-dipole broadband antenna according to any one of claims 1 to 6.

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