Hybrid structure circularly polarized scanning antenna

Abstract

The application discloses a circularly polarized scanning antenna with a mixed structure, which comprises a first antenna, a second antenna and a third antenna, wherein the first antenna, the second antenna and the third antenna are stacked together with a preset distance from top to bottom, the first antenna comprises an upper dielectric plate and a lower dielectric plate connected by a plurality of short-circuit columns, the upper surface of the upper dielectric plate and the lower surface of the lower dielectric plate are respectively plated with a metal layer, the second antenna comprises a cylindrical metal reflector and a cylindrical dielectric plate coaxially arranged from inside to outside, the outer surface of the cylindrical dielectric plate is printed with a plurality of dipole pairs, and the third antenna has the same structure as the first antenna. The omnidirectional directional free switching can be realized by a conventional method, the omnidirectional gain is higher, the directional scanning gain is relatively good, and the circular polarization effect is good.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of antennas, in particular to a hybrid structure circularly polarized scanning antenna. BACKGROUND

[0002] The omnidirectional circularly polarized antenna has omnidirectional and circularly polarized characteristics, and approximately uniformly radiates circularly polarized waves in 360° directions in the horizontal plane. It can send communication signals to all directions and receive electromagnetic signals from all directions in the horizontal plane, and is widely used in large-scale communication and point-to-multipoint communication systems. Nowadays, with the coexistence of the fifth generation (5G) mobile communication and 4G, Bluetooth, Internet of Things (IoT) and other wireless networks, the working environment of the antenna becomes more complex, thus further promoting the research of omnidirectional circularly polarized antennas.

[0003] In 2019, X. Miao, W. Wan, et al. of Nanjing University of Information Engineering proposed an omnidirectional antenna based on a dipole in "Design of Dual-Mode Arc-Shaped Dipole Arrays for Indoor Base-Station Applications," (IEEE Antennas and Wireless Propagation Letters, vol. 18, no. 4, pp. 752-756, April 2019). The antenna structure is simple and the function is single, and it cannot be switched directionally, so it is not widely applicable. In 2018, Xin meng Lv, Wen quan Cao, et al. of the Army Engineering University proposed a circularly polarized beam scanning antenna using a surface plasmon polariton (SPP) structure in "A Circularly Polarized Frequency Beam-Scanning Antenna Fed by a Microstrip Spoof SPP Transmission Line," (IEEE Antennas and Wireless Propagation Letters, vol. 17, no. 7, pp. 1329-1333, July 2018). The antenna cannot switch between omnidirectional and directional with conventional methods while maintaining circular polarization characteristics, and its scanning gain needs to be improved. SUMMARY

[0004] The present application aims to solve the problems existing in the prior art, and provides a hybrid structure circularly polarized scanning antenna. The omnidirectional and directional free switching of the present application can be realized by conventional methods, and the omnidirectional gain is higher and the directional scanning gain is relatively good, while the circular polarization effect is also good.

[0005] Technical scheme: The mixed structure circularly polarized scanning antenna comprises a first antenna, a second antenna and a third antenna, the first antenna, the second antenna and the third antenna are stacked together with a preset distance from top to bottom, the first antenna comprises an upper dielectric plate and a lower dielectric plate connected by a plurality of short-circuit columns, the upper surface of the upper dielectric plate and the lower surface of the lower dielectric plate are respectively plated with a metal layer, the second antenna comprises a cylindrical metal reflector and a cylindrical dielectric plate coaxially arranged from inside to outside, the outer surface of the cylindrical dielectric plate is printed with a plurality of dipole pairs, and the third antenna is the same in structure as the first antenna.

[0006] Further, the first antenna further comprises a coaxial line, one end of the coaxial line penetrates the upper dielectric plate to connect the metal layer of the upper dielectric plate, and the other end penetrates the lower dielectric plate to connect the metal layer of the lower dielectric plate.

[0007] Further, the metal layer of the upper dielectric plate is provided with a ring-shaped groove at the center position, and a plurality of fan-shaped grooves are arranged around the ring-shaped groove.

[0008] Preferably, the number of fan-shaped grooves is 4, the sizes are the same, and the fan-shaped grooves are uniformly arranged at equal distances around the ring-shaped groove.

[0009] Further, the second antenna further comprises a plurality of coaxial lines, one end of the coaxial line is connected to the cylindrical metal reflector, and the other end penetrates the cylindrical dielectric plate to connect the dipole on the surface.

[0010] Preferably, the number of coaxial lines is specifically 4, and the coaxial lines are uniformly distributed between the cylindrical metal reflector and the cylindrical dielectric plate.

[0011] Preferably, the dipole is a square ring, and the dipole arm is provided with a slot.

[0012] Further, the first antenna, the second antenna and the third antenna are respectively placed on a support plate, and the support plates are connected together through a plurality of support columns.

[0013] Preferably, the upper and lower dielectric plates of the first antenna and the third antenna are circular, and the cylindrical metal reflector and the cylindrical dielectric plate of the second antenna are both cylindrical.

[0014] Beneficial effects: Compared with the prior art, the present application has the following advantages: the present application combines two different types of omnidirectional circularly polarized antennas together to realize higher omnidirectional gain and relatively better directional scanning gain, while maintaining good circular polarization effect, which is different from the single structure of most existing scanning antennas, and the present application can realize the conversion between omnidirectional circularly polarized mode and single-beam directional circularly polarized mode based on the maximum power transmission efficiency method. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a perspective view of a hybrid structure of the circularly polarized scanning antenna provided by the present application;

[0016] Figure 2 is an exploded schematic view of Figure 1 ;

[0017] Figure 3 is a perspective view of the first antenna in Figure 1 ;

[0018] Figure 4 is an exploded schematic view of Figure 3 ;

[0019] Figure 5 is a perspective view of the second antenna in Figure 1 ;

[0020] Figure 6 is a side view (a) and a top view (b) of Figure 5 ;

[0021] Figure 7 is a simulation reflection coefficient |S 11 | graph of the omnidirectional mode of the present application;

[0022] Figure 8 is a simulation axial ratio graph of the omnidirectional mode of the present application, (a) is a graph of the axial ratio and frequency of the present application; (b) is an axial ratio pattern of the present application at 3.5 GHz;

[0023] Figure 9 is an xoy plane and xoz plane pattern at 3.5 GHz of the omnidirectional mode of the present application, (a) is a left-handed circular polarization and right-handed circular polarization radiation pattern of the xoy plane, (b) is a left-handed circular polarization and right-handed circular polarization radiation pattern of the xoz plane;

[0024] Figure 10 is an antenna gain curve graph of the omnidirectional mode of the present application in the entire working frequency band;

[0025] Figure 11 is a single-beam pointing at 3.5 GHz of the directional mode of the present application, taking phi=0 deg, phi=0 deg, phi=90 deg as an example of the radiation pattern. DETAILED DESCRIPTION

[0026] The embodiment provides a hybrid structure of a circularly polarized scanning antenna, as shown in Figure 1 and Figure 2 , the overall size of the antenna is 68 2 ×π×142mm 3, including a first antenna 1, a second antenna 2 and a third antenna 3, the first antenna 1, the second antenna 2 and the third antenna 3 are sequentially arranged from top to bottom, the first antenna 1, the second antenna 2 and the third antenna 3 are respectively placed on a support plate 4, the support plates 4 are connected together through a plurality of support columns 5, the support columns are nylon support columns, the third antenna 3 and the first antenna 1 are the same structure, and the second antenna 2 is different in structure.

[0027] As shown in Figure 3 and Figure 4 , the first antenna 1 includes an upper layer dielectric plate 101, a lower layer dielectric plate 102, a short circuit column 103 and a coaxial line 104, the upper layer dielectric plate 101 and the lower layer dielectric plate 102 are connected through the short circuit column 103. The short circuit column 103 is 4, and it can be understood that in other embodiments, the short circuit column 103 can also be other numbers, for example, 8. The upper surface of the upper layer dielectric plate 101 is plated with a metal layer 105, and the lower surface of the lower layer dielectric plate 102 is plated with a metal layer 106. One end of the coaxial line 104 passes through the upper layer dielectric plate 101 to connect the metal layer 105 of the upper layer dielectric plate 101, and the other end passes through the lower layer dielectric plate 102 to connect the metal layer 106 of the lower layer dielectric plate 102. The metal layer 105 of the upper layer dielectric plate 102 has a ring-shaped groove 105a at the center position, and four fan-shaped grooves 105b are provided around the ring-shaped groove 105a. The fan-shaped grooves 105b are the same size and are uniformly arranged at equal distances around the ring-shaped groove 105a. It can be understood that in other embodiments, the number of fan-shaped grooves 105b can also be other numbers, for example, 8. The upper layer dielectric plate 101 and the lower layer dielectric plate 102 are circular, and it can be understood that in other embodiments, they can also be other shapes, for example, square. The entire structure of the first antenna 1 is center-symmetric, and it is a single-port omnidirectional circularly polarized antenna. The short circuit column 103 of the first antenna 1 provides a vertical polarization component, and the metal layer 105 and the metal layer 106 provide a horizontal polarization component.

[0028] As shown in Figure 5 and Figure 6 , the second antenna includes a cylindrical metal reflector plate 201, a cylindrical dielectric plate 202 and a coaxial line 204, the cylindrical metal reflector plate 201 is inside the cylindrical dielectric plate 202, and the two are air, the thickness of the cylindrical metal reflector plate 201 is 0.5mm, the radius is 19mm, the material of the cylindrical dielectric plate 202 is transparent resin, the dielectric constant is 3.0, the loss tangent angle is 0.05, the inner radius is 32mm, the height is 40mm, and the thickness is 1mm. The outer surface of the cylindrical dielectric plate 202 is printed with four pairs of annular dipoles 203, which are respectively located 270° four directions, the two arms of the dipole 203 conform to the inner and outer walls of the cylindrical dielectric plate, the coupling between adjacent dipoles helps to broaden the bandwidth. It can be understood that in other embodiments, the dipole 203 can also be other numbers, for example, 8 pairs. The ring width of the dipole 203 is 1.8mm, the total length of the ring is about 80mm, the slot length is 3.8mm, the width is 1.8mm, the square ring dipole helps to broaden the working bandwidth of the antenna, and the slot helps to circularly polarize the antenna. The coaxial line 204 is connected to the cylindrical metal reflector plate 201 at one end, and is connected to the surface dipole 203 through the cylindrical dielectric plate 202 at the other end. The coaxial line 204 is 4 in number and is uniformly distributed between the cylindrical metal reflector plate 201 and the cylindrical dielectric plate 202. It can be understood that in other embodiments, the number of coaxial lines 204 can be other numbers, for example, 8, consistent with the number of pairs of dipoles. The second antenna 2 is a center-symmetric structure, which is a 4-port omnidirectional circularly polarized antenna. The square ring dipole is used as the radiator, and the cylindrical metal reflector plate 201 is used for reflection, realizing the wide working frequency range and omnidirectional circular polarization characteristics of the antenna. The cylindrical metal inside the dielectric plate ensures that the design has good omnidirectional and directional radiation characteristics.

[0029] The omnidirectional mode and the directional mode of the antenna of the embodiment require that different amplitude and phase excitations be added to all ports. The optimal amplitude and phase of each port are calculated by the maximum power transmission efficiency method to realize omnidirectional and directional switching.

[0030] As Figure 7 The simulation reflection coefficient |S 11 |Fig. 2 shows that the working bandwidth of the antenna is 2.96-4.85GHz, and the relative bandwidth is 48.3%, which can well cover the 5G trial frequency band of China Unicom. As Figure 8 (a) is the axial ratio curve of the omnidirectional mode of the antenna of the embodiment, and from the figure it can be seen that the axial ratio bandwidth of the antenna is 2.88GHz-3.80GHz, and the part with AR<3 has 920MHz, and the relative bandwidth is 27.5%. As Figure 8 (b) is the axial ratio pattern of the antenna in the theta=90° plane at 3.5GHz in the omnidirectional mode of the antenna of the embodiment. It can be seen that the axial ratio of the antenna is less than 3dB, i.e. it is realized omnidirectional circular polarization. As Figure 9 is the omnidirectional mode of the antenna of the embodiment, at this time the omnidirectional gain of the antenna of the embodiment is 6.40dBic, and the non-circularity is 0.8dB. At the same time, in the xoy and xoz planes at 3.5GHz, by comparing the left-handed circular polarization and right-handed circular polarization gain, it can be seen that the main polarization is left-handed circular polarization, and the cross-polarization is less than-20dB (i.e. the right-handed circular polarization is less than-20dB). As Figure 10For the gain curve of the invention in the omnidirectional mode, the gain of the antenna in the operating bandwidth is greater than generally greater than 4.2dBic, and the maximum actual gain reaches 6.8dBic. Figure 11 For the invention in the directional mode, the horizontal single-beam radiation pattern at 3.5GHz, only the radiation patterns of the beams pointing to 0°, 45° and 90° are selected due to the symmetrical structure, and it can be seen from the figure that the directional gains in each direction are 8.4dBic, 7.3dBic and 8.4dBic respectively, and the axial ratio when the directional beam points to is less than 3dB. It can be seen from the above that the invention can realize the horizontal 360° directional single-beam scanning function at 3.5GHz, and the directional gain is more than 7.1dBic.

[0031] The invention combines two different types of omnidirectional circularly polarized antennas together to realize higher omnidirectional gain and relatively better directional scanning gain, while maintaining good circular polarization effect. This mixed structure not only realizes the effect of high gain, but also guarantees high gain when pointing directionally and good non-circularity when omnidirectional. These all meet the performance requirements of future micro base station antennas. The invention is applied to the 5G trial frequency band (3500-3600MHz) of China Unicom, and the simulation results of its operating frequency band are 2.96-4.85GHz, covering the 5G trial frequency band of China Unicom.

[0032] The above only discloses one preferred embodiment of the invention, and cannot limit the scope of the invention, so equivalent changes made according to the claims of the invention still fall within the scope of the invention.

Claims

1. A hybrid structured circularly polarized scanning antenna, characterized in that: The application relates to a single-feed omnidirectional circularly polarized antenna, which comprises a first antenna, a second antenna and a third antenna, the first antenna, the second antenna and the third antenna are stacked together at a preset distance from top to bottom, the first antenna comprises an upper dielectric plate and a lower dielectric plate connected by a plurality of short-circuit columns, the upper surface of the upper dielectric plate and the lower surface of the lower dielectric plate are respectively plated with a metal layer, the second antenna comprises a cylindrical metal reflector and a cylindrical dielectric plate coaxially arranged from inside to outside, the outer surface of the cylindrical dielectric plate is printed with a plurality of dipole pairs, the third antenna is identical in structure to the first antenna, the whole structure of the first antenna is central symmetric, and the first antenna is a single-port omnidirectional circularly polarized antenna; the whole structure of the second antenna is central symmetric, and the second antenna is a 4-port omnidirectional circularly polarized antenna; the short-circuit columns of the first antenna provide a vertical polarization component; the metal layer on the upper surface of the upper dielectric plate and the metal layer on the lower surface of the lower dielectric plate provide a horizontal polarization component; the omnidirectional mode and the directional mode of the antenna require that different amplitude and phase excitations are added to all ports; the optimal amplitude and phase of each port are calculated by the maximum power transmission efficiency method, and omnidirectional and directional switching is realized.

2. The hybrid structured circularly polarized scanning antenna according to claim 1, wherein: The first antenna further comprises coaxial lines, one end of the coaxial lines is connected to the metal layer of the upper dielectric plate through the upper dielectric plate, and the other end of the coaxial lines is connected to the metal layer of the lower dielectric plate through the lower dielectric plate.

3. The hybrid structured circularly polarized scanning antenna according to claim 1, wherein: The metal layer of the upper dielectric plate is provided with a ring-shaped slot at a central position, and a plurality of fan-shaped slots are arranged around the ring-shaped slot.

4. The hybrid structured circularly polarized scanning antenna according to claim 3, wherein: The number of the fan-shaped slots is four, the fan-shaped slots are identical in size and are uniformly arranged at equal distances around the ring-shaped slot.

5. The hybrid structured circularly polarized scanning antenna according to claim 1, wherein: The second antenna further comprises a plurality of coaxial lines, one end of the coaxial lines is connected to the cylindrical metal reflector, and the other end of the coaxial lines is connected to the dipole on the surface of the cylindrical dielectric plate.

6. The hybrid structured circularly polarized scanning antenna according to claim 5, wherein: The number of the coaxial lines is four, and the coaxial lines are uniformly distributed between the cylindrical metal reflector and the cylindrical dielectric plate.

7. The hybrid structured circularly polarized scanning antenna according to claim 1, wherein: The dipole is a square ring.

8. The hybrid structured circularly polarized scanning antenna according to claim 1, wherein: The dipole arm is provided with a slot.

9. The hybrid structured circularly polarized scanning antenna according to claim 1, wherein: The first antenna, the second antenna and the third antenna are respectively placed on a support plate, and the support plates are connected together through a plurality of support columns.

10. The hybrid structured circularly polarized scanning antenna according to claim 1, wherein: The upper and lower dielectric plates of the first antenna and the third antenna are circular, and the cylindrical metal reflector and the cylindrical dielectric plate of the second antenna are both cylindrical.

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