A broadband circularly polarized antenna with a quasi-hemispherical beam coverage in the Ka band

Abstract

The present invention relates to a broadband circularly polarized antenna with a quasi-hemispherical beam coverage in the Ka band, belonging to the field of electronic science and technology. It includes a metal ring, a dielectric plate, a metal curved body, a circular waveguide, and a metal bottom plate. The upper opening of the metal curved body covers the dielectric plate, and the lower opening is covered by the metal bottom plate; the circular waveguide is placed inside the metal curved body, the upper opening is connected to the top opening of the metal curved body, and the lower opening is connected to the metal bottom plate; the structure of the combination of the metal ring and the metal curved body designed by the present invention effectively broadens the beam width and maintains the axial symmetry (quasi-hemispherical) of the radiation pattern. The use of a circular waveguide stepped septum circular polarizer for feeding has a simple structure and low loss.

Description

Technical Field

[0001] The present invention belongs to the field of electronic science and technology. In particular, a realization scheme of a circularly polarized antenna in the millimeter-wave Ka band is provided. The antenna has a wide frequency band, a radiation pattern with good axial symmetry, and can achieve a wide beam similar to hemispherical coverage. It can be applied to the communication system of a moving vehicle. Background Art

[0002] On a moving vehicle, in order to maintain stable communication quality in different postures, the antenna is required to have a relatively wide lobe width so as to achieve wide-angle domain gain coverage and ensure information transmission and reception in a wide-angle domain. For example, in radio systems such as communication and navigation on moving vehicles such as vehicles, ships, airplanes, and satellites, the antenna is required to have the characteristics of a wide frequency band and an ultra-wide beam (approximate half-space coverage). At present, most of these antennas are linearly polarized wide-beam or narrow-band circularly polarized wide-beam antennas, and it is often impossible to balance the characteristics of a wide frequency band, circular polarization, and wide beam.

[0003] The wide-band circularly polarized wide-beam antenna is applicable to various radio systems that need to achieve a coverage similar to half-space. For example: communication, satellite navigation and other systems. In mobile communication, the wide-band circularly polarized wide-beam antenna has unique advantages. Especially when applied to a moving vehicle, when the posture of the vehicle changes within a certain range, it can well adapt to the posture change of the moving vehicle and maintain the stable operation of the load system of the moving vehicle.

[0004] The existing wide-band circularly polarized wide-beam antennas are usually realized by forms such as conical helix, magnetoelectric dipole, microstrip antenna, and crossed dipole; the magnetoelectric dipole has a very wide impedance bandwidth, but its electric dipole and magnetic dipole are asymmetric structures, which results in large fluctuations in the symmetry of its radiation pattern with the change of frequency; the working bandwidth of the microstrip antenna and the self-phase shift antenna is relatively narrow.

[0005] In the millimeter-wave Ka band, since the working wavelength is in the millimeter range, the corresponding physical size of the antenna is very small, and the existing antennas have defects such as difficult processing, difficult assembly, poor engineering feasibility, and unstable performance. Summary of the Invention

[0006] Technical Problem to be Solved

[0007] In order to avoid the deficiencies of the prior art, the present invention proposes a broadband circularly polarized antenna with a hemispherical beam coverage in the Ka band.

[0008] Technical Solution

[0009] A Ka-band broadband circularly polarized antenna with a quasi-hemispherical beam coverage, characterized by comprising a metal ring, a dielectric plate, a metal curved body, a circular waveguide, a stepped partition, a feeding probe and a metal bottom plate. The upper opening of the metal curved body covers the dielectric plate, and the lower opening is covered by the metal bottom plate. The circular waveguide is placed inside the metal curved body, with its upper opening connected to the top opening of the metal curved body and its lower opening connected to the metal bottom plate. The metal ring is a double-ring double-layer structure, and the double rings are respectively covered on the upper and lower surfaces of the dielectric plate. The inner surface of the circular waveguide is a cylindrical surface, and the outer surface is a square cylindrical surface. Two circular holes for installing the feeding probes are opened along the diameter direction on the lower side wall. The inner diameter of the cylindrical surface is the same as the inner diameter of the circular hole at the top of the metal curved body. The stepped partition is located inside the circular waveguide and acts as a circular polarizer, exciting a circularly polarized wave inside the circular waveguide.

[0010] The outer surface of the metal curved body is a parabolic surface, and the surface is axisymmetric about the central axis, and the central axis is coaxial with the axis of the circular waveguide.

[0011] An annular groove for inlaying the dielectric plate is provided at the edge of the opening at the top of the metal curved body.

[0012] The stepped partition is a stepped metal thin plate, placed inside the circular waveguide along the axis of the circular waveguide. The width of the widest section is the same as the inner diameter of the circular waveguide. The two vertical sides are in contact with the inner wall of the circular waveguide, and the bottom side is in contact with the bottom surface of the circular waveguide.

[0013] The feeding probe is the core wire of a coaxial cable, and two feedings are used to differentially feed the circular waveguide.

[0014] Beneficial effects

[0015] A Ka-band broadband circularly polarized antenna proposed by the present invention solves the problems of circular polarization and hemispherical beam coverage of Ka-band antennas.

[0016] 1. The present invention uses the circular waveguide aperture as a radiator, with good beam symmetry and low loss in the Ka band.

[0017] 2. The structure of the combination of the metal ring and the metal curved body designed by the present invention effectively broadens the beam width and maintains the axisymmetry (quasi-hemispherical) of the radiation pattern. The feeding using the circular waveguide stepped partition circular polarizer has a simple structure and low loss.

[0018] 3. The present invention adopts the form of a circular waveguide opening, with a simple structure and easy implementation. Especially in the Ka band, where the wavelength is only a few millimeters, the antenna has a small size, can be formed in one processing, and has high consistency.

[0019] 4. The present invention uses a waveguide circular polarizer for feeding. Compared with the microstrip type, the waveguide type has low loss and high efficiency. Brief description of the drawings

[0020] The accompanying drawings are only for the purpose of showing specific embodiments and are not considered as limiting the present invention. Throughout the drawings, the same reference signs denote the same components.

[0021] Figure 1 This is the external shape diagram of the antenna according to the embodiment of the present invention;

[0022] Figure 2 This is the structural composition diagram of the antenna according to the embodiment of the present invention;

[0023] Figure 3 This is the internal structure diagram of the metal curved surface body of the antenna according to the embodiment of the present invention;

[0024] Figure 4 This is the voltage standing wave ratio characteristic of the antenna according to the embodiment of the present invention;

[0025] Figure 5 This is the antenna gain pattern (f = 32 GHz) according to the embodiment of the present invention;

[0026] Figure 6 This is the antenna gain pattern (f = 36 GHz) according to the embodiment of the present invention;

[0027] Figure 7 This is the antenna gain pattern (f = 40 GHz) according to the embodiment of the present invention. Detailed implementation manners

[0028] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0029] The present invention proposes a realization scheme for a wide-beam (hemispherical beam-like coverage), broadband, circularly polarized antenna in the millimeter-wave Ka band. The antenna is composed of seven parts, and is characterized by including: a metal ring 1, a dielectric plate 2, an annular groove 3, a metal curved surface body 4, a circular waveguide 5, a stepped partition 6, a feeding probe 7, and a metal bottom plate 8, consisting of a total of 8 components. The upper opening of the metal curved surface body 4 covers the dielectric plate 2, and the lower opening is covered by the metal bottom plate 8; the circular waveguide 5 is placed inside the metal curved surface body 4, the upper opening is connected to the top opening of the metal curved surface body 4, and the lower opening is connected to the metal bottom plate 8.

[0030] In the above scheme, the metal ring 1 has a double-ring double-layer structure, and the double rings are respectively covered on the upper and lower surfaces of the dielectric plate 2.

[0031] In the above solution, the dielectric plate 2 covers the annular groove 3 at the circular waveguide opening. The dielectric plate 2 serves a dual purpose of fixing the position of the metal ring 1 and sealing the antenna. An annular magnetic current is formed between the metal ring 1 and the circular waveguide opening, and the annular magnetic current has the effect of broadening the radiation beam width of the circular waveguide opening.

[0032] In the above solution, the annular groove 3 is a groove at the edge of the opening at the top of the metal curved body 4 and is used to inlay the dielectric plate 2.

[0033] In the above solution, the curved surface on the outer surface of the metal curved body 4 is axisymmetric about the central axis, maintaining the axisymmetry of the antenna pattern and at the same time having the effect of broadening the beam width.

[0034] In the above solution, the inner surface of the circular waveguide 5 is a cylindrical surface, the outer surface is a square cylindrical surface, and two circular holes are opened along the diameter direction on the lower side wall for feeding.

[0035] In the above solution, the stepped partition 6 is inside the circular waveguide 5 and acts as a circular polarizer, exciting a circularly polarized wave inside the circular waveguide 5.

[0036] In the above solution, the feeding probe 7 is the coaxial core wire, and two feeds are used for differential feeding of the circular waveguide 5.

[0037] To enable those skilled in the art to better understand the present invention, the present invention will be described in detail below in conjunction with specific embodiments.

[0038] As Figures 1 - 3 shown, it is a structural diagram of an antenna of an embodiment of a Ka millimeter-wave hemispherical beam broadband circularly polarized antenna of the present invention. Its structure includes 7 parts: metal ring 1, dielectric plate 2, annular groove 3, metal curved body 4, circular waveguide 5, stepped partition 6, feeding probe 7.

[0039] The metal ring 1 is a double-layer planar metal patch; the upper and lower metal rings of the metal ring 1 are respectively covered on the upper and lower surfaces of the dielectric plate 2.

[0040] The dielectric plate 2 uses Rogers 5880 with a thickness of 0.5 mm. Metal rings 1 are etched on both of its surfaces, mainly serving to support and fix the metal ring 1. The dielectric plate 2 is fixed at the annular groove 3 at the top of the metal curved body 4.

[0041] The annular groove 3 is an annular blind groove structure, located at the edge of the top circular hole at the top of the metal curved body 4, and is a groove structure. The groove radius is slightly larger than the diameter of the circular waveguide 5 and is used to inlay the dielectric plate 2.

[0042] The outer surface of the metal curved body 4 takes a paraboloid and is rotationally symmetric about the central axis. The central axis is coaxial with the axis of the circular waveguide 5. The metal curved body 4 is a hollow structure, with a circular hole opened at the top, the hole diameter being the same as the inner diameter of the circular waveguide, and the lower opening diameter being the same as the diameter of the metal bottom plate.

[0043] The circular waveguide 5 has a circular inner and square outer shape, and its inner diameter is determined by the corresponding operating frequency band.

[0044] The stepped separator 6 is a stepped metal thin plate, which is placed along the axis of the circular waveguide inside the circular waveguide. The width of the widest section is the same as the inner diameter of the circular waveguide, and the two vertical sides are in contact with the inner wall of the circular waveguide 5, and the bottom side is in contact with the bottom surface of the circular waveguide 5.

[0045] The feeding probe 7 is an extension of the inner core of the coaxial cable, located on the bottom side wall of the circular waveguide 5, on both sides of the stepped separator 6, along the diameter direction, and perpendicular to the stepped separator 6.

[0046] For the above-described embodiment antenna, it is fed by the feeding probe 7, and the circularly polarized wave excited by the separator circular polarizer formed by the stepped separator 6 and the circular waveguide 5 radiates circularly polarized electromagnetic waves into space from the circular waveguide aperture field. The metal ring 1, the annular groove 3, and the metal curved body 4 play a role in broadening the beam width.

[0047] The simulation results of the above-described embodiment antenna show that:

[0048] As Figure 4 shown, it is the characteristic of the voltage standing wave ratio of the embodiment antenna varying with the operating frequency.

[0049] Figures 5 - 7 It is the circular polarization gain pattern of the embodiment antenna.

[0050] From Figures 4 - 7 it can be seen that the bandwidth with a voltage standing wave ratio not greater than 2 is 22.2%, and the beam coverage range with a gain greater than 0 dBic exceeds ±65°. The pattern has good axial (Z-axis) symmetry and a quasi-hemispherical beam coverage characteristic.

[0051] The simulation results show that the embodiment antenna in the millimeter-wave Ka band can generate a wide beam (quasi-hemispherical) coverage with good axial symmetry, and has broadband and circular polarization characteristics.

[0052] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should be covered within the protection scope of the present invention.

Claims

1. A broadband circularly polarized antenna with a quasi-hemispherical beam coverage in the Ka band, characterized in that It includes a metal ring (1), a dielectric plate (2), a metal curved surface body (4), a circular waveguide (5), a stepped partition (6), a feeding probe (7) and a metal bottom plate (8). The upper opening of the metal curved surface body (4) covers the dielectric plate (2), and the lower opening is covered by the metal bottom plate (8). The circular waveguide (5) is placed inside the metal curved surface body (4), with its upper opening connected to the top opening of the metal curved surface body (4) and its lower opening connected to the metal bottom plate (8). The metal ring (1) is a double-ring double-layer structure, and the double rings are respectively covered on the upper and lower surfaces of the dielectric plate (2). The inner surface of the circular waveguide (5) is a cylindrical surface, and the outer surface is a square cylindrical surface. Two circular holes for installing the feeding probe (7) are opened in the lower side wall along the diameter direction. The inner diameter of the cylindrical surface is the same as the inner diameter of the circular hole at the top of the metal curved surface body (4). The stepped partition (6) is located inside the circular waveguide (5) and acts as a circular polarizer to excite a circularly polarized wave inside the circular waveguide (5). The outer surface of the metal curved surface body (4) is a paraboloid, and the curved surface is axisymmetric about the central axis, and the central axis is coaxial with the axis of the circular waveguide (5). An annular groove (3) for inlaying the dielectric plate (2) is provided at the edge of the opening at the top end of the metal curved surface body (4). The annular groove (3) is an annular blind groove structure, which is a groove structure, and the groove radius is slightly larger than the caliber of the circular waveguide (5). The stepped partition (6) is a stepped metal thin plate, which is placed inside the circular waveguide along the axis of the circular waveguide. The width of the widest section is the same as the inner diameter of the circular waveguide, and the two vertical sides are in contact with the inner wall of the circular waveguide (5), and the bottom side is in contact with the bottom surface of the circular waveguide (5). The feeding probe (7) is the core wire of a coaxial cable, and two feedings are used to differentially feed the circular waveguide (5). The circularly polarized wave excited by the feeding probe (7) and through the partition circular polarizer composed of the stepped partition (6) and the circular waveguide (5) radiates circularly polarized electromagnetic waves into the space in the direction of the circular waveguide caliber field. The metal ring (1), the annular groove (3) and the metal curved surface body (4) play the role of broadening the beam width.

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