EP3819984B1

EP3819984B1 - Wide-angle scanning dual-polarized dipole antenna

Info

Publication number: EP3819984B1
Application number: EP20806225.7A
Authority: EP
Inventors: Jia FANG; Qingchao ZHU; Tao Jiang; Weiying CAI; Mouping JIN; Quan Wang
Original assignee: CETC 38 Research Institute
Current assignee: CETC 38 Research Institute
Priority date: 2019-05-15
Filing date: 2020-05-14
Publication date: 2024-05-01
Anticipated expiration: 2040-05-14
Also published as: EP3819984A1; JP2021524699A; WO2020228759A1; CN110176666B; EP3819984A4; JP7025596B2; CN110176666A

Description

TECHNICAL FIELD

The present invention relates to the technical field of antennas, and particularly relates to a wide-angle scanning dual-polarization dipole antenna.

BACKGROUND OF THE PRESENT INVENTION

An antenna is one of the most important components in systems of wireless broadcasting, wireless communication and wireless detection, and its structure and characteristics determine the working performance of the entire system to a great extent. A phased array antenna has become an important development direction of the modern antenna because of its excellent beam scanning and beamforming capacity. Radar, communication and other systems often require the phased array antenna to have the characteristics of wide working frequency band, large scanning angle, low return loss, etc. The antennas in some special applications often need to have strong environmental adaptability to adapt to harsh working conditions.
A dual-polarization antenna is composed of two polarization mutually-orthogonal antennas and is widely used in modern radar, communication and other systems. Conventional forms of the dual-polarization antenna include microstrip antennas, dipole antennas, Vivaldi antennas, etc. The crisscross dual-polarization antenna composed of two mutually-orthogonal dipole antennas has the advantages of wide bandwidth, low machining difficulty, high reliability and the like and is usually used as an arraying unit of the dual-polarization phased array.
However, impedance of the traditional dual-polarization dipole antenna may have dramatic changes during large-angle scanning, thereby further leading to impedance mismatch, and causing serious return loss. When scanning at ±60°, the return loss of an antenna unit is always up to -6dB. On the other hand, the antenna in some special application fields always encounters complicated working environments and extreme weather such as heavy rainfall, heavy snowfall, etc. The traditional dual-polarization dipole antenna often has a large cross sectional area and is prone to snow accumulation, thereby greatly affecting the working time of the antenna.
Chinese patent application No. CN103682631A discloses a multi-standard multi-band dual-polarized antenna, which includes a reflecting plate, wherein the reflecting plate is provided with a plurality of low-frequency radiation units and a plurality of high-frequency radiation units; each low-frequency radiation unit comprises a guide sheet, a fixed medium, a radiator, a Balun and a feed conductor.
United States patent application No. US2011/057848A1 discloses an antenna apparatus that may be implemented using a single antenna feed and impedance matching network with a low profile antenna shape that optimizes over-the-horizon gain, with no requirement for a ground plane. The antenna apparatus may also be implemented to cover the entire UHF SATCOM frequency band using a single antenna feed.
United States patent application No. US2007/200783A1 discloses a broadband dipole including two co-working conductors. A first of the conductors is comprised of a rod including a substantially centrally located axial hole, said hole forming an outer conductor of a coaxial line, and that the second conductor is comprised of a solid rod, and that a metallic wire inserted centrally in the axial hole of the first conductor is connected to the second conductor.

SUMMARY OF THE PRESENT INVENTION

Technical problems to be solved by the present invention are how to realize low return loss and wide-angle scanning and how to meet working needs under extreme weathers such as heavy rainfall, heavy snowfall and the like and to provide a wide-angle scanning dual-polarization dipole antenna.
The present invention adopts the following technical solution to solve the above technical problems. The present invention includes first metal arms, an antenna support column, second metal arms and feed baluns.
The first metal arms are located at the top of the antenna and used to improve impedance fluctuation of the antenna during large-angle scanning.
The feed baluns are located at the bottom of the antenna and used to convert an unbalanced feed input by a coaxial wire to a balanced feed.
The antenna support column is located between the feed baluns and the first metal arms and used to support the first metal arms.
The second metal arms are arranged at an outer upper ends of the feed baluns and fed respectively by the feed baluns.
The first metal arms are longitudinal cross-blade-shaped metal arms. The second metal arms are longitudinal blade-shaped metal dipole arms. Each of the first metal arms and the second metal arms includes a horizontal portion and a bending portion. The horizontal portion and the bending portion are integrally-molded members. With small cross sectional area, the metal arms in the above shape are not prone to rain and snow accumulation, so that the antenna is integrally high in wind resistance and rain and snow resistance and can adapt to extreme weather and complicated working environment. By adopting the longitudinal cross-blade-shaped metal arms, the impedance fluctuation of the antenna during the large-angle scanning is improved.
Preferably, the number of the second metal arms is two groups, in a total of four second metal arms. The two groups of second metal arms are distributed symmetrically.
Preferably, the antenna adopts a symmetric structure, so that two polarization directions are mutually orthogonal.
Preferably, the number of feed baluns is two groups. The two groups of feed baluns are mutually orthogonal, so that the feed baluns can conveniently feed the two groups of dipole arms with mutually-orthogonal polarization directions respectively.
Preferably, each group of feed baluns includes a coaxial wire, an earthing metal column, a metal bridge and a medium substrate. The metal bridge is arranged on the medium substrate. The medium substrate is arranged at the upper ends of the coaxial wire and the earthing metal column. The metal bridge is used to connect the coaxial wire and the earthing metal column.
Preferably, each group of feed baluns further includes a plurality of medium support columns. The coaxial wire includes a coaxial inner conductor and a coaxial outer conductor. The coaxial inner conductor is located inside the coaxial outer conductor. The plurality of medium support columns are arranged outside the coaxial inner conductor respectively. The coaxial inner conductor is fixed by the medium support columns.
Preferably, a parallel doublet structure is formed between the coaxial outer conductor and the earthing metal column. The two groups of second metal arms are fixedly welded respectively on the coaxial outer conductor and the earthing metal column and fed by the parallel doublet structure.
Preferably, the bending portion is bent downwards. A bending angle of the second metal arm is kept consistent with the first metal arm. The downwards bending can play a role in guiding rain and snow.
Compared with the prior art, the present invention has the following advantages: the wide-angle scanning dual-polarization dipole antenna greatly improves impedance matching during large-angle scanning of the antenna and effectively improves wide-angle scanning performance of the antenna. The wide-angle scanning of ±60° in a range of 208 MHz-260 MHz is realized, and a voltage standing-wave ratio during the scanning is less than 1.5. Compared with the traditional dipole antenna, the voltage standing-wave ratio during scanning at a wide angle of ±60° is well suppressed. Meanwhile, the antenna has good cross polarization performance. A cross polarization level is less than -25dB. Finally, since both the metal dipole arms and the top metal arms adopt a longitudinal blade-shaped bending structure respectively, and the cross sectional area is extremely small, snow and rain are not prone to accumulate, thereby greatly reducing the influence of accumulated snow and rain on performance and service life of the antenna. The antenna is especially applicable to severe weather conditions such as heavy rainfall, heavy snowfall and the like.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is an overall structural schematic diagram of the present invention;
Fig. 2 is a local exploded view of the present invention;
Fig. 3 is a side section view of Fig. 1 of the present invention;
Fig. 4 is a top view of Fig. 1 of the present invention;
Fig. 5 is a schematic diagram of a voltage standing-wave ratio during scanning of an antenna; and
Fig. 6 is a cross polarization direction pattern of the antenna at a frequency point of 230 MHz.

In the drawings: 1, first metal arm; 2, antenna support column; 3, second metal arm; 4, feed balun; 41, coaxial inner conductor; 42, coaxial outer conductor; 43, earthing metal column; 44, medium support column; 45, metal screw; 46, metal bridge; 47, medium substrate.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

Embodiments of the present invention are described in detail below. The present embodiment is implemented on the premise of the technical solution of the present invention. Detail implementations and specific operating processes are illustrated, but the protection scope of the present invention is not limited to the embodiment described below.
As shown in Fig. 1, the present embodiment provides a technical solution: a wide-angle scanning dual-polarization dipole antenna includes first metal arms 1, an antenna support column 2, second metal arms 3 and feed baluns 4.
The first metal arms 1 are located at the top of the antenna and used to improve impedance fluctuation of the antenna during large-angle scanning.
The feed baluns 4 are located at the bottom of the antenna and used to convert an unbalanced feed input by a coaxial wire to a balanced feed.
The antenna support column 2 is located between the feed baluns 4 and the first metal arms 1 and used to support the first metal arms 1.
The second metal arms 3 are arranged at an outer upper ends of the feed baluns 4 and fed respectively by the feed baluns 4.
The first metal arms 1 are longitudinal cross-blade-shaped metal arms. The first metal arms 1 are parasitic units and are not fed. The second metal arms 3 are longitudinal blade-shaped metal dipole arms. Each of the first metal arms 1 and the second metal arms 3 includes a horizontal portion and a bending portion. The horizontal portion and the bending portion are integrally-molded members. The bending portion is bent downwards. A bending angle of the second metal arm is kept consistent with the first metal arm. The downwards bending can play a role in guiding rain and snow. The metal arms in the above shape have small cross sectional areas and are not prone to rain and snow accumulation, so that the antenna is integrally high in wind resistance and rain and snow resistance and can adapt to the extreme weather and complicated working environment. By adopting the longitudinal cross-blade-shaped metal arms, the impedance fluctuation of the antenna during the large-angle scanning can be improved.
The working frequency of the antenna is 208 MHz-260 MHz. A polarization way includes horizontal polarization and vertical polarization. The antenna units are distributed in a form of triangular lattices. Spacing among the antenna units in the horizontal polarization direction is 740 mm, and spacing among the antenna units in the vertical polarization direction is 640 mm. When the antenna is distributed in the practical triangular lattice form, the number of transverse and longitudinal units can be increased according to actual needs. Similarly, the antenna can also be distributed in a rectangular lattice form, an annular form or other forms according to the actual needs.
The first metal arms 1 include two mutually-orthogonal longitudinal blade-shaped metal arms. Each of the longitudinal blade-shaped metal arms has a transverse length of 370 mm, a longitudinal height of 106 mm and a width of 3 mm, and are arranged at the upper ends of the antenna support columns 2. The metal arms 1 are fixed to the antenna support columns 2 by screws or in other ways. The antenna support column 2 is made of polytetrafluoroethylene material with a dielectric coefficient Dk of 2.1. Each of the antenna support columns 2 has a maximum diameter of 95 mm and a height of 45 mm, and is arranged on the feed baluns 4. The antenna support columns 2 are fixed to the feed baluns 4 by screws or in other ways.
As shown in Figs. 2-4, the number of feed baluns 4 is two groups. The two groups of feed baluns 4 are mutually orthogonal, so that the feed baluns can conveniently feed the two groups of dipole arms with two mutually-orthogonal polarization directions. Each group of baluns 4 includes a coaxial wire, an earthing metal column 43, a metal bridge 46 and a medium substrate 47. The metal bridge 46 is arranged on the medium substrate 47 and is fixed respectively by four metal screws 45. The medium substrate 47 is arranged at the upper ends of the coaxial wire and the earthing metal column 43. The metal bride 46 is used to connect the coaxial wire and the earthing metal column 43. Each group of feed baluns 4 also includes a plurality of medium support columns 44. The coaxial wire includes a coaxial inner conductor 41 and a coaxial outer conductor 42. The coaxial inner conductor 41 is located inside the coaxial outer conductor 42. The plurality of medium support columns 44 are arranged respectively outside the coaxial inner conductors 41. A parallel doublet structure is formed between the coaxial outer conductor 42 and the earthing metal column 43. The two groups of second metal columns 3 are fixedly welded on the coaxial outer conductor 42 and the earthing metal column 43 respectively and fed by the parallel doublet structure.
It should be noted that the coaxial outer conductor 42 and the earthing metal column 43 are symmetric in position and have a same size with a diameter (an outer diameter of the coaxial outer conductor 42) of 28.08 mm and a height is 423.7 mm, and spacing between the two is 25.86 mm. The coaxial outer conductor 42 may be taken as a hollow metal sleeve with an inner diameter of 24 mm. The coaxial inner conductor 41 is located at the center of the coaxial outer conductor 42, has the same height with the coaxial outer conductor 42, and is fixed by the polytetrafluoroethylene medium support columns 44. The diameter of the coaxial inner conductor 41 is determined according to an impedance change need and according to whether the inner conductor penetrates through the medium support columns 44. The maximum diameter is 10 mm, and the minimum diameter is 4.774 mm. The bottom of the coaxial inner conductor 41 is connected with a coaxial radio-frequency connector for feeding.
The metal bridge 46 has a total length of 64 mm and a width of 10 mm. Minimum spacing among the metal bridge 46, the coaxial outer conductor 42 and the earthing metal column 43 is 9 mm. Two arms of the longitudinal blade-shaped metal dipole arms are welded at the outer top ends of the coaxial outer conductor 42 and the earthing metal column 43 and fed successively by the coaxial outer conductor 42, the coaxial inner conductor 41, the metal bridge 46 and the earthing metal column 43. Each dipole arm has a transverse length of 190 mm, a longitudinal height of 238 mm and a thickness of 3 mm.
The antenna support column 2, the medium support columns 44 and the medium substrate 47 are made of polytetrafluoroethylene, and other structures are made of metal materials. The longitudinal cross-blade-shaped metal arms greatly improve the impedance mismatch of the antenna during the scanning. Adding the cross-blade-shaped metal arms is substantially to introduce capacitance and inductance into an equivalent circuit of the antenna, thereby changing a resonance point and impedance during the large-angle scanning. The blade-shaped metal arm structure provides high wind and snow resistance and is applicable to the extreme weather environment.
As shown in Fig. 5, when horizontal polarization and vertical polarization are scanned at ±60° in an E /H plane, a voltage standing-wave ratio is less than 1.5 in the range of 208MHz-260MHz, which realizes a wide-angle scanning process with low return loss.
As shown in Fig. 6, an E/H-plane pattern of the antenna has no obvious deterioration within a bandwidth, and a cross polarization level is less than -25dB.
In conclusion, the wide-angle scanning dual-polarization dipole antenna in the present embodiment greatly improves impedance matching during the large-angle scanning of the antenna and effectively improves wide-angle scanning performance of the antenna. The wide-angle scanning of ±60° in a range of 208MHz-260MHz is realized, and a voltage standing-wave ratio during the scanning is less than 1.5. Compared with the traditional dipole antenna, the voltage standing-wave ratio during the scanning at a wide angle of ±60°is well suppressed. Meanwhile, the antenna has good cross polarization performance. The cross polarization level is less than -25dB. Finally, since both the metal dipole arms and the top metal arms adopt a longitudinal blade-shaped bending structure respectively, and the cross sectional area is extremely small, snow and rain are not prone to accumulate, thereby greatly reducing the influence of accumulated snow and rain on performance and service life of the antenna. The antenna is especially applicable to severe weather conditions such as heavy rainfall, heavy snowfall and the like.

Claims

A wide-angle scanning dual-polarization dipole antenna, comprising first metal arms (1), an antenna support column (2), second metal arms (3) and feed baluns (4), wherein
the first metal arms (1) are located at the top of the antenna and are configured to improve impedance fluctuation of the antenna during large-angle scanning;

the feed baluns (4) are located at the bottom of the antenna and are configured to convert an unbalanced feed input by a coaxial wire to a balanced feed;

the antenna support column (2) is located between the feed baluns (4) and the first metal arms (1) and is configured to support the first metal arms (1);

the second metal arms (3) are arranged on the feed baluns (4) and configured to be fed respectively by the feed baluns (4);

the first metal arms (1) are longitudinal cross-blade-shaped metal arms;

the second metal arms (3) are longitudinal blade-shaped metal dipole arms;

each of the first metal arms (1) and the second metal arms (3) comprises a horizontal portion and a bending portion; and the horizontal portion and the bending portion are integrally-molded members;

the antenna being configured such that when horizontal polarization and vertical polarization are scanned at ± 60° in an E /H plane, a voltage standing-wave ratio is less than 1.5 during the scanning in the range of 208 MHz-260 MHz.
The wide-angle scanning dual-polarization dipole antenna according to claim 1, wherein the number of the second metal arms (3) is two groups, in a total of four second metal arms; polarization directions of the two groups of second metal arms (3) are mutually orthogonal; and the two groups of second metal arms (3) are distributed symmetrically.
The wide-angle scanning dual-polarization dipole antenna according to claim 1, wherein the antenna adopts a symmetric structure, so that two polarization directions are mutually orthogonal.
The wide-angle scanning dual-polarization dipole antenna according to claim 2, wherein the number of feed baluns (4) is two groups; and the two groups of feed baluns (4) are mutually orthogonal, so that the feed baluns (4) feed the two groups of metal dipole arms with mutually-orthogonal polarization directions respectively.
The wide-angle scanning dual-polarization dipole antenna according to claim 4, wherein each group of feed baluns (4) comprises a coaxial wire, an earthing metal column (43), a metal bridge (46) and a medium substrate (47); the metal bridge (46) is arranged on the medium substrate (47); the medium substrate (47) is arranged at the upper ends of the coaxial wire and the earthing metal column (43); and the coaxial wire and the earthing metal column (43) are connected through the metal bridge (46).
The wide-angle scanning dual-polarization dipole antenna according to claim 5, wherein each group of feed baluns further comprises a plurality of medium support columns (44); the coaxial wire comprises a coaxial inner conductor (41) and a coaxial outer conductor (42); the coaxial inner conductor (41) is located inside the coaxial outer conductor (42); the plurality of medium support columns (44) are arranged outside the coaxial inner conductor (41) respectively; and the coaxial inner conductor (41) is fixed by the medium support columns(44).
The wide-angle scanning dual-polarization dipole antenna according to claim 6, wherein a parallel doublet structure is formed between the coaxial outer conductor (42) and the earthing metal column (43) ;and the two groups of second metal arms (3) are fixed on the coaxial outer conductor (42) and the earthing metal column (43) respectively and fed by the parallel doublet structure.
The wide-angle scanning dual-polarization dipole antenna according to claim 1, wherein the bending portion is bent downwards; and a bending angle of the second metal arm (3) is kept consistent with the first metal arm (1).