Satellite array antenna based on mirror image subarray
Technical Field
The invention designs a satellite array antenna based on a mirror image subarray, which has the characteristics of high gain, dual polarization, low side lobe, small size, low cross polarization and the like.
Background
One of the key technologies in a satellite communication system is an antenna technology, and the satellite communication antenna usually requires an antenna having the characteristics of high efficiency, low loss, dual linear polarization, circular polarization, and the like. The technology of the antenna for the communication in motion particularly needs the characteristic of small size of the antenna. Although the traditional reflector antenna has a simple structure and is easy to realize high gain, the traditional reflector antenna has a large volume and is not easy to install, so that the planar array antenna which has a small size, high efficiency and is easy to integrate is widely applied. In the dual-polarized planar array antenna, a waveguide-based planar array antenna needs to be selected to realize high Q value and low loss, because the microstrip patch planar array antenna is easy to integrate with a radio frequency rear end, the antenna radiation efficiency is low, the unit mutual coupling is strong, and the overall radiation performance of the antenna is further deteriorated as the design working frequency of the antenna is increased. However, the dual-polarized waveguide array antenna feed network occupies a large space and has a large weight, so that the antenna structure in the traditional form is difficult to simultaneously meet the technical requirements of small size, low side lobe, low loss and the like.
Disclosure of Invention
In order to solve the problems, the invention provides a satellite array antenna based on a mirror image sub-array, which can simultaneously meet the technical requirements of small size, low side lobe, low loss and the like under the condition of integrating a feed network.
The technical scheme adopted by the invention is as follows:
the polarization form of the antenna is double linear polarization and works in a Ku frequency band, four small sub-arrays with all-copper structures are closely arranged in a 2 multiplied by 2 rectangular array form to form the antenna, adjacent sub-arrays in one direction of the rectangular array are mutually mirror-symmetrical by a central line vertical to the direction, and adjacent sub-arrays in the other vertical direction of the matrix array are arranged identically and are in a translation duplication relationship with each other.
Each subarray is mainly formed by arranging 16 radiation units in a 4 multiplied by 4 mode, the 16 radiation units are connected through the same feed network, each radiation unit is in a single-side step back cavity type horn unit, each radiation unit comprises a radiation outer cavity and a radiation inner cavity, the radiation inner cavity is fixedly arranged on the bottom surface of the radiation outer cavity, and the radiation outer cavities of the multiple radiation units are integrated into the same one; the side surface of one side of the radiation inner cavity is provided with a stepped surface structure, and the stepped surface structures of the radiation inner cavities of the plurality of radiation units are arranged on the same side.
The feed network is mainly composed of two square coaxial structures containing a plurality of cylindrical conductor inner cores, the two square coaxial structures are tightly nested structures, the square coaxial structure is a horizontal polarization power division feed structure, and the square coaxial structure is a vertical polarization power division feed structure; the square coaxial power division structure is designed according to four stages from bottom to top, and each stage of power division of the square coaxial power division is positioned at the upper layer of the same stage of power division of the square coaxial power division. The square coaxial inner part is respectively provided with a matching power dividing structure formed by connecting 180 and 220 cylindrical conductor inner cores with different lengths and inner diameters along the axis direction, an annular Teflon structure is arranged between the cylindrical conductor inner cores and the square coaxial inner wall for fixing, and the different lengths and inner diameters ensure that the impedances of the different cylindrical conductor inner cores are different;
the square coaxial connector is connected to the lower side of the radiation inner cavity of the radiation unit, and the square coaxial connector is connected to the feed cavity outside the radiation unit; the square coaxial feed ports are all located at the bottom of the whole structure, quasi-TEM waves are input from the feed ports and transmitted to the inside of the radiation unit from the bottom to the top along the power division structure along the inner core of the cylindrical conductor.
The outer side and the inner side of a single side wall of a radiating unit of the antenna both comprise stepped surface structures. .
The stepped surface structure comprises four steps of mutually different sizes.
The feed network is all copper except for a ring-shaped Teflon structure which is fixedly needed.
The square coaxial pair radiating element adopts probe feeding on the side wall positioned on the symmetrical side of the stepped surface structure, or the square coaxial pair radiating element adopts probe feeding in the feeding cavity positioned on the symmetrical side of the stepped surface structure.
The feed network comprises a horizontal polarization feed port and a vertical polarization feed port, the horizontal polarization feed ports of the subarrays which are mirror symmetric to each other feed in opposite phases, and the vertical polarization feed ports of the subarrays which are mirror symmetric to each other feed in the same phase.
The dielectric constant of the annular Teflon structure is 2.1.
The Ku frequency band mainly comprises two frequency bands of 12.25GHz-12.75GHz and 14GHz-14.5 GHz.
The invention combines the square coaxial radiating unit with the horn radiating unit, thereby realizing very compact array antenna structure and higher radiation efficiency.
The invention can solve the problems of the existing satellite array antenna structure in the communication in motion, and has the advantages that:
1. under the condition of high Q value, the square coaxial structure with the cylindrical conductor inner core is adopted, so that the technical problems of difficult integration, large size, high loss and the like of the existing horn type satellite array antenna structure adopting waveguide or coaxial feed in motion can be solved.
2. The low cross polarization is realized in a dual-frequency band under the conditions of low loss, compactness, small size and only one-time phase reversal of a feed network and a sub-array, and can even reach below-70 dB under ideal conditions.
Drawings
Fig. 1 is a schematic structural diagram of an 8 × 8 satellite array antenna.
In the figure: 1. 2, 3, 4 denote 4 × 4 sub-arrays.
Fig. 2 is a schematic diagram of the structure of the radiating element.
In the figure: 5 denotes a radiation outer cavity, 6 denotes a radiation inner cavity, 7 denotes a stepped surface structure, 8 denotes a horizontally polarized feed probe, and 9 denotes a vertically polarized feed probe.
Fig. 3 is a schematic diagram of a 4 × 4 sub-array at different angles.
In the figure: 10 denotes a horizontally polarized power dividing feed structure, 11 denotes a vertically polarized power dividing feed structure, 12 denotes a cylindrical conductor inner core of the horizontally polarized power dividing feed structure, 13 denotes a cylindrical conductor inner core of the vertically polarized power dividing feed structure, 14 denotes a feed cavity, 15 denotes a horizontally polarized feed port, and 16 denotes a vertically polarized feed port.
Fig. 4 is a schematic structural diagram of a cylindrical conductor core with a square coaxial structure.
In the figure: (a) the power dividing structure is a cylindrical conductor inner core power dividing structure in the horizontal polarization power dividing feed structure, the power dividing structure is a cylindrical conductor inner core power dividing structure in the vertical polarization power dividing feed structure, and 17 represents an annular Teflon structure.
Figure 5 is an E-plane far-field radiation pattern for a horizontal polarization of an 8 x 8 satellite array antenna.
In the figure: (a) the antenna is an 8 × 8 satellite array antenna 12.5GHz horizontally polarized E-plane main polarized far-field radiation pattern, (b) the 8 × 8 satellite array antenna 12.5GHz horizontally polarized E-plane cross-polarized far-field radiation pattern, (c) the 8 × 8 satellite array antenna 14.25GHz horizontally polarized E-plane main polarized far-field radiation pattern, and (d) the 8 × 8 satellite array antenna 14.25GHz horizontally polarized E-plane cross-polarized far-field radiation pattern.
Fig. 6 is an H-plane far-field radiation pattern for an 8 x 8 satellite array antenna with horizontal polarization.
In the figure: (a) the antenna is an 8 × 8 satellite array antenna 12.5GHz horizontally polarized H-plane main polarized far-field radiation pattern, (b) the 8 × 8 satellite array antenna 12.5GHz horizontally polarized H-plane cross polarized far-field radiation pattern, (c) the 8 × 8 satellite array antenna 14.25GHz horizontally polarized H-plane main polarized far-field radiation pattern, and (d) the 8 × 8 satellite array antenna 14.25GHz horizontally polarized H-plane cross polarized far-field radiation pattern.
Figure 7 is an E-plane far-field radiation pattern for a vertical polarization of an 8 x 8 satellite array antenna.
In the figure: (a) the antenna is an E-plane main polarized far-field radiation pattern with vertical polarization at a frequency point of 12.5GHz of an 8 × 8 satellite array antenna, (b) the E-plane cross-polarized far-field radiation pattern with vertical polarization at the frequency point of 12.5GHz of the 8 × 8 satellite array antenna, (c) the E-plane main polarized far-field radiation pattern with vertical polarization at the frequency point of 14.25GHz of the 8 × 8 satellite array antenna, and (d) the E-plane cross-polarized far-field radiation pattern with vertical polarization at the frequency point of 14.25GHz of the 8 × 8 satellite array antenna.
Figure 8 is an H-plane far-field radiation pattern for a vertical polarization of an 8 x 8 satellite array antenna.
In the figure: (a) the antenna is an H-plane main polarized far-field radiation pattern with vertical polarization at a frequency point of 12.5GHz of an 8 × 8 satellite array antenna, (b) the H-plane cross polarized far-field radiation pattern with vertical polarization at the frequency point of 12.5GHz of the 8 × 8 satellite array antenna, (c) the H-plane main polarized far-field radiation pattern with vertical polarization at the frequency point of 14.25GHz of the 8 × 8 satellite array antenna, and (d) the H-plane cross polarized far-field radiation pattern with vertical polarization at the frequency point of 14.25GHz of the 8 × 8 satellite array antenna.
Detailed Description
The invention will be further explained with reference to the drawings.
Example (b):
fig. 1 shows a satellite array antenna structure used in the present embodiment, and the satellite array antenna is composed of 64 radiation units of 8 × 8. The array antenna is composed of four sub-arrays (1, 2, 3 and 4), each sub-array is provided with an independent feed network, the sub-arrays (1, 2), (3 and 4) along the horizontal polarization direction are in mirror symmetry, and the feed network and the radiation unit are in mirror symmetry at the same time.
Fig. 2 shows the structure of the radiation unit, which mainly consists of a radiation outer cavity (5) and a radiation inner cavity (6). The radiation outer cavity is the position of the radiation unit for radiating electromagnetic waves outwards, and the caliber of the radiation outer cavity is larger than that of the radiation inner cavity, so that higher gain and radiation efficiency are realized. One side of the radiation inner cavity is designed into a step-type surface structure (7), so that the radiation unit can realize good radiation performance in two sub-bands of a Ku frequency band. The horizontal polarization feed is arranged on the lower portion of the symmetrical surface of the radiation inner cavity stepped surface structure of the radiation unit, and the vertical polarization feed is arranged on the upper portion of the symmetrical surface of the radiation inner cavity stepped surface structure of the radiation unit.
Fig. 3 shows the sub-array structure in fig. 1 from different angles, the sub-array is composed of 16 radiation units of 4 × 4, two feed ports are arranged in the sub-array, the feed port 15 is a horizontal polarization port, the feed port 16 is a vertical polarization port, the square coaxial structures (11, 12) connected with the ports are respectively feed networks of horizontal and vertical polarization, the feed networks of horizontal and vertical polarization are nested tightly, the square coaxial structures are designed according to a bottom-up and top-level power division structure, each level of power division of the horizontal polarization power division feed structure is located at the upper layer of the same level of power division of the vertical polarization power division feed structure, the inner cores (13, 14) of the cylindrical conductors are arranged along the axial direction, and the square coaxial outer conductors are connected and integrated with the radiation units. By CSTTMThe radiating performance of the satellite array antenna can be obtained by simulating the satellite array antenna by using Microwave Studio full-wave simulation software.
Fig. 4 shows a schematic diagram of a power division structure of a cylindrical conductor inner core inside a square coaxial structure, and fig. 4(a) and 4(b) show power division structures designed according to an impedance matching theory for 180 and 220 cylindrical conductor inner cores with different lengths and inner diameters, respectively. The structure of performing power division feeding from bottom to top greatly reduces the area size of the satellite array antenna and enhances the integration between the feeding network and the radiation unit.
According to the directional diagrams shown in fig. 5, 6, 7 and 8, it can be seen that the sidelobe power of the satellite array antenna structure provided by the invention at the frequency points of 12.5GHz and 14.5GHz is averagely lower than 13.3dB and the cross polarization isolation in the maximum radiation direction is extremely high, the main lobe gain of the horizontal polarization at the frequency point of 12.5GHz is 27.1dB, the cross polarization in the maximum radiation direction is about-70 dB, the main lobe gain of the horizontal polarization at the frequency point of 14.5GHz is 28.4dB, the cross polarization in the maximum radiation direction is about-80 dB, the main lobe gain of the vertical polarization at the frequency point of 12.5GHz is 27.8dB, the cross polarization in the maximum radiation direction is less than-100 dB, the main lobe gain of the vertical polarization at the frequency point of 14.5GHz is 28.8dB, and the cross polarization in the maximum radiation direction is about-100 dB. The designed small-size satellite array antenna has the characteristics of high gain, high isolation and the like.
Fig. 5(a) shows a horizontally polarized E-plane main polarized far-field radiation pattern at a frequency point of 12.5GHz of the 8 × 8 satellite array antenna, fig. 5(b) shows a horizontally polarized E-plane cross-polarized far-field radiation pattern at a frequency point of 12.5GHz of the 8 × 8 satellite array antenna, fig. 5(c) shows a horizontally polarized E-plane main polarized far-field radiation pattern at a frequency point of 14.25GHz of the 8 × 8 satellite array antenna, and fig. 5(d) shows a horizontally polarized E-plane cross-polarized far-field radiation pattern at a frequency point of 14.25GHz of the 8 × 8 satellite array antenna.
Fig. 6(a) shows a horizontally polarized H-plane main polarized far-field radiation pattern at the frequency point of 12.5GHz of the 8 × 8 satellite array antenna, fig. 6(b) shows a horizontally polarized H-plane cross polarized far-field radiation pattern at the frequency point of 12.5GHz of the 8 × 8 satellite array antenna, fig. 6(c) shows a horizontally polarized H-plane main polarized far-field radiation pattern at the frequency point of 14.25GHz of the 8 × 8 satellite array antenna, and fig. 6(d) shows a horizontally polarized H-plane cross polarized far-field radiation pattern at the frequency point of 14.25GHz of the 8 × 8 satellite array antenna.
Fig. 7(a) shows a vertically polarized E-plane main polarized far-field radiation pattern at the frequency point of 12.5GHz of the 8 × 8 satellite array antenna, fig. 7(b) shows a vertically polarized E-plane cross-polarized far-field radiation pattern at the frequency point of 12.5GHz of the 8 × 8 satellite array antenna, fig. 7(c) shows a vertically polarized E-plane cross-polarized far-field radiation pattern at the frequency point of 14.25GHz of the 8 × 8 satellite array antenna, and fig. 7(d) shows a vertically polarized E-plane cross-polarized far-field radiation pattern at the frequency point of 14.25GHz of the 8 × 8 satellite array antenna.
Fig. 8(a) shows a vertically polarized H-plane main polarized far-field radiation pattern at the frequency point of 12.5GHz of the 8 × 8 satellite array antenna, fig. 8(b) shows a vertically polarized H-plane cross polarized far-field radiation pattern at the frequency point of 12.5GHz of the 8 × 8 satellite array antenna, fig. 8(c) shows a vertically polarized H-plane main polarized far-field radiation pattern at the frequency point of 14.25GHz of the 8 × 8 satellite array antenna, and fig. 8(d) shows a vertically polarized H-plane cross polarized far-field radiation pattern at the frequency point of 14.25GHz of the 8 × 8 satellite array antenna.