A low-scattering hybrid beam antenna array

Abstract

The present invention provides a low-scattering hybrid beam antenna array, comprising a reflector, a low-frequency antenna array, a high-frequency antenna array, and a feed network; the low-frequency antenna array and the high-frequency antenna array are mixedly arranged above the reflector, and the feed network is installed below the reflector; the feed network feeds the low-frequency antenna array and the high-frequency antenna array respectively; the low-frequency antenna array comprises a plurality of low-scattering antenna units; the radiating arms of the low-scattering antenna units comprise four L-shaped metal patches respectively arranged at the four corners of a square and a parasitic patch arranged at the center of the square, and each two adjacent L-shaped metal patches are connected by a U-shaped branch. The present invention achieves conformal radiation patterns and low-scattering characteristics by improving the antenna unit structure in the array; while meeting regional coverage and solving the problem of insufficient capacity, it effectively reduces the installation space required for the hybrid beam antenna array.

Description

Technical Field

[0001] The present invention relates to the field of communication antennas, and in particular to a low-scattering hybrid beam antenna array. Background Art

[0002] With the rapid development of mobile communications and the internet, network data traffic has surged. Mobile communication terminal base stations, on the one hand, need wide-beam antennas that can address signal area coverage in order to be compatible with multiple operating frequency bands such as 2G / 3G / 4G / 5G, conserve site resources, and reduce the number of base station antennas installed. However, spectrum resources are now precious, and the communication bandwidth and capacity of base stations in areas with dense mobile communication users are very limited. During peak periods, populations gather and data traffic is high, making it difficult for traditional single-beam base station antennas to meet channel bandwidth requirements. This necessitates increasing channel capacity through the use of beam splitting. Therefore, it is necessary to develop a hybrid beam antenna array that can simultaneously meet regional coverage and address capacity constraints. At the same time, to reduce interference between different antennas, reduce the required installation space, and save costs, designing a hybrid beam array antenna with low-scattering characteristics has become an urgent need in the current development of base station antennas.

[0003] Chinese utility model patent application number CN202222841215.9 discloses a hybrid beam antenna and communication device. By forming a concave structure between the base plate and the extension plate, this effectively narrows the horizontal beamwidth of the low-frequency antenna to meet antenna coverage requirements. However, the antenna array requires a large installation space, which is not conducive to widespread use. Chinese invention patent application number CN202110798540.9 discloses a low-scattering antenna and a multi-frequency antenna array thereof. This antenna unit achieves low-scattering performance through multiple radiating branches of varying lengths, but the low-scattering bandwidth is relatively narrow, at 14%.

[0004] It can be seen that the hybrid beam antenna array in the prior art needs to be further improved and perfected. Summary of the Invention

[0005] The purpose of the present invention is to provide a low-scattering hybrid beam antenna array to address the problems existing in the prior art. By improving the antenna unit structure in the array, the radiation pattern is conformal and low-scattering characteristics are achieved. While meeting regional coverage and solving the problem of insufficient capacity, the installation space required for the hybrid beam antenna array is effectively reduced.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A low-scattering hybrid beam antenna array comprises a reflector, a low-frequency antenna array, a high-frequency antenna array and a feed network;

[0008] The low-frequency antenna array and the high-frequency antenna array are mixedly arranged above the reflector, and the feeding network is installed below the reflector; the feeding network feeds the low-frequency antenna array and the high-frequency antenna array respectively, so that the low-frequency antenna array and the high-frequency antenna array are both arranged on the reflector in a ±45° dual-polarization manner;

[0009] The low-frequency antenna array includes a plurality of low-scattering antenna units; the low-scattering antenna units include a first dielectric plate, an antenna radiator, a first feed balun and a second feed balun;

[0010] The antenna radiator includes four radiating arms printed on the upper surface of a first dielectric plate. The four radiating arms are rotationally symmetrically distributed along the circumference with the center of the first dielectric plate as the center of the circle and at intervals of 90 degrees. Two of the radiating arms arranged opposite to each other constitute a first half-wave dipole, and the other two radiating arms arranged opposite to each other constitute a second half-wave dipole. The two half-wave dipoles are fed respectively by a first feeding balun and a second feeding balun to form dual-polarized radiation.

[0011] The four radiating arms have the same shape and structure; the shape of a single radiating arm is a square as a whole, and each radiating arm includes four L-shaped metal patches respectively arranged at the four corners of the square and a parasitic patch arranged at the center of the square, and each adjacent two L-shaped metal patches are connected by a U-shaped branch; the width of the U-shaped branch is smaller than the width of the L-shaped metal patch, and the total length of the U-shaped branch is one-quarter wavelength of the working center frequency of the high-frequency antenna array.

[0012] Furthermore, in the low-scattering antenna unit, the bottom of the U-shaped branch is arranged toward the parasitic patch, the opening of the U-shaped branch is arranged toward the outside of the radiation arm, and both ends of the U-shaped branch are respectively connected to the L-shaped metal patches on both sides.

[0013] Further, in the low-scattering antenna unit, the first feed balun and the second feed balun are vertically cross-connected to each other;

[0014] Two complementary circular grooves are etched on the metal patches of the first feed balun and the second feed balun; the complementary circular grooves include two concentrically nested arc-shaped grooves, wherein the opening of the inner arc-shaped groove is set upward, and the opening of the outer arc-shaped groove is set downward.

[0015] Furthermore, in the low-scattering antenna unit, the first feed balun includes a first feed balun dielectric plate, a first microstrip transmission line, a first slot transmission line, and a first coupling feed point; the first microstrip transmission line is printed on the front surface of the first feed balun dielectric plate; a metal patch is printed on each of the left and right halves of the back surface of the first feed balun dielectric plate, and the two metal patches are spaced a certain distance apart to form a first slot transmission line extending in a vertical direction in the middle of the back surface of the first feed balun dielectric plate; the projections of the first microstrip transmission line and the first slot transmission line on the first feed balun dielectric plate partially overlap to form a first coupling feed point;

[0016] The upper end of the first feed balun dielectric plate is vertically plugged into the first dielectric plate. The upper ends of the two metal patches on the back of the first feed balun dielectric plate pass through the first dielectric plate and are respectively welded to the two radiating arms constituting the first half-wave dipole. The lower end of one of the metal patches is electrically connected to the outer conductor of the first coaxial cable. The inner conductor of the first coaxial cable passes through the first feed balun dielectric plate and is electrically connected to the first microstrip transmission line.

[0017] The second feed balun includes a second feed balun dielectric plate, a second microstrip transmission line, a second slot transmission line, and a second coupling feed point; the second microstrip transmission line is printed on the front surface of the second feed balun dielectric plate; a metal patch is printed on each of the left and right halves of the back surface of the second feed balun dielectric plate, and the two metal patches are spaced a certain distance apart to form a second slot transmission line extending in a vertical direction in the middle of the back surface of the second feed balun dielectric plate; the projections of the second microstrip transmission line and the second slot transmission line on the second feed balun dielectric plate partially overlap to form a second coupling feed point;

[0018] The upper end of the second feed balun dielectric plate is vertically plugged into the first dielectric plate, the upper ends of the two metal patches on the back side of the second feed balun dielectric plate pass through the first dielectric plate and are respectively welded to the two radiating arms constituting the second half-wave dipole, the lower end of one of the metal patches is electrically connected to the outer conductor of the second coaxial cable, and the inner conductor of the second coaxial cable passes through the second feed balun dielectric plate and is electrically connected to the second microstrip transmission line;

[0019] A complementary circular groove is etched on each of the two metal patches on the back of the first feed balun dielectric plate, and a complementary circular groove is also etched on each of the two metal patches on the back of the second feed balun dielectric plate; the complementary circular grooves on the first feed balun dielectric plate and the second feed balun dielectric plate are located at the same height.

[0020] Furthermore, in the low-scattering antenna unit, a slot opening upward is provided above the middle of the first feed balun dielectric board, and a slot opening downward is provided below the middle of the second feed balun dielectric board; the first feed balun dielectric board and the second feed balun dielectric board are plugged into each other through the slot in the middle, so that the first feed balun and the second feed balun are vertically cross-connected to each other.

[0021] Furthermore, in the low-scattering antenna unit, the welding points of the two metal patches on the back of the first feed balun dielectric plate and the two metal patches on the back of the second feed balun dielectric plate and the radiating arm are located at the corners of the L-shaped metal patch of the radiating arm toward the center of the first dielectric plate.

[0022] Furthermore, the high-frequency antenna array includes a first high-frequency antenna subarray, a second high-frequency antenna subarray, a third high-frequency antenna subarray, and a fourth high-frequency antenna subarray, which are sequentially arranged in parallel and side by side along the Y-axis direction, and each high-frequency antenna subarray includes four high-frequency antenna units arranged at equal intervals along the X-axis direction;

[0023] The low-frequency antenna array includes two low-scattering antenna units arranged along the X-axis direction; the two low-scattering antenna units are arranged between the second high-frequency antenna subarray and the third high-frequency antenna subarray in the Y-axis direction; in the X-axis direction, one of the low-scattering antenna units is arranged between the first two high-frequency antenna units of the high-frequency antenna subarray, and the other low-scattering antenna unit is arranged between the last two high-frequency antenna units of the high-frequency antenna subarray.

[0024] Furthermore, the feeding network includes a low-frequency power splitting unit, a first high-frequency power splitting unit, a second high-frequency power splitting unit, a third high-frequency power splitting unit, a fourth high-frequency power splitting unit, a first Butler matrix, and a second Butler matrix;

[0025] The low-frequency power splitter unit is connected to the low-frequency antenna array and is used to transmit a feed signal to the low-frequency antenna array;

[0026] The input ends of the first Butler matrix and the second Butler matrix are respectively connected to an external power supply, the output end of the first Butler matrix outputs a +45° polarized signal, and the output end of the second Butler matrix outputs a -45° polarized signal;

[0027] The first Butler matrix has a first output end, a second output end, a third output end and a fourth output end, and the second Butler matrix also has a first output end, a second output end, a third output end and a fourth output end; the first output end of the first Butler matrix and the first output end of the second Butler matrix are fed to the first high-frequency antenna subarray through the first high-frequency power splitter unit, the second output end of the first Butler matrix and the second output end of the second Butler matrix are fed to the second high-frequency antenna subarray through the second high-frequency power splitter unit, the third output end of the first Butler matrix and the third output end of the second Butler matrix are fed to the third high-frequency antenna subarray through the third high-frequency power splitter unit, and the fourth output end of the first Butler matrix and the fourth output end of the second Butler matrix are fed to the fourth high-frequency antenna subarray through the fourth high-frequency power splitter unit, thereby realizing ±45° dual polarization of the high-frequency antenna unit;

[0028] Among them, the signal ratio of the first output end, the second output end, the third output end and the fourth output end of the first Butler matrix is ​​1:2:2:1, and the signal ratio of the first output end, the second output end, the third output end and the fourth output end of the second Butler matrix is ​​1:2:2:1.

[0029] Furthermore, the first Butler matrix and the second Butler matrix have the same structure, and respectively include a Butler matrix dielectric plate and a first directional coupler, a second directional coupler, a third directional coupler, a fourth directional coupler, a first 45° phase shifter, a second 45° phase shifter, a first one-to-two power splitter, and a second one-to-two power splitter printed on the Butler matrix dielectric plate;

[0030] The input ends of the first directional coupler and the second directional coupler serve as the input ends of the Butler matrix and are connected to an external feed power source through a coaxial cable for power supply; the output ends of the first directional coupler and the second directional coupler are connected to the input ends of the third directional coupler and the fourth directional coupler through a first 45° phase shifter and a second 45° phase shifter;

[0031] One output end of the third directional coupler is connected to the input end of the first one-to-two power splitter, one output end of the first one-to-two power splitter is connected to the first output end of the Butler matrix, and the other output end of the first one-to-two power splitter is welded to the first ohm resistor and then grounded to achieve signal diversion; the other output end of the third directional coupler is connected to the second output end of the Butler matrix; one output end of the fourth directional coupler is connected to the third output end of the Butler matrix; the other output end of the fourth directional coupler is connected to the input end of the second one-to-two power splitter, one output end of the second one-to-two power splitter is connected to the fourth output end of the Butler matrix, and the other output end of the second one-to-two power splitter is welded to the second ohm resistor and then grounded to achieve signal diversion; through the first one-to-two power splitter and the second one-to-two power splitter, the signal ratio of the first output end, the second output end, the third output end and the fourth output end of the Butler matrix is ​​1:2:2:1.

[0032] Furthermore, the first high-frequency power splitting unit, the second high-frequency power splitting unit, the third high-frequency power splitting unit and the fourth high-frequency power splitting unit have the same structure; each high-frequency power splitting unit includes a first one-to-four power splitter and a second one-to-four power splitter;

[0033] An input end of the first one-to-four power divider is connected to the first Butler matrix, and four output ends of the first one-to-four power divider are respectively connected to the +45° polarization direction balun feeds of the four high-frequency antenna units in the corresponding high-frequency antenna subarray;

[0034] The input end of the second one-to-four power divider is connected to the second Butler matrix, and the four output ends of the second one-to-four power divider are respectively connected to the -45° polarization direction balun feed of the four high-frequency antenna units in the corresponding high-frequency antenna subarray.

[0035] The present invention provides a low-scattering hybrid beam antenna array that utilizes improved low-scattering antenna units to form a low-frequency antenna array. These low-scattering antenna units, based on a conventional ring structure, incorporate parasitic patches and U-shaped branches with a total length roughly corresponding to one-quarter the wavelength of the high-frequency antenna unit's operating center frequency. When the high-frequency antenna array is operating, the tapered width structure on the radiating arms of the low-scattering antenna units effectively produces a low-pass filtering effect. Simultaneously, coupling currents from the high frequency are concentrated on the edges of the U-shaped branches and parasitic patches, offsetting each other and reducing the coupling effect between different antennas. This ensures a conformal radiation pattern and achieves low-scattering characteristics.

[0036] In addition, the present invention also realizes unequal power distribution of the signals of the four output ports of the Butler matrix of the present invention by connecting a power divider to the output end of the traditional Butler matrix, thereby reducing the level of the side lobes of the radiation pattern of the high-frequency antenna array and improving the radiation performance of the antenna array.

[0037] The present invention provides a low-scattering hybrid beam antenna array, which achieves low-scattering characteristics only by improving the antenna unit structure itself. It has the characteristics of compact structure and does not require the addition of additional components. While meeting regional coverage and solving the problem of insufficient capacity, it effectively reduces the installation space required for the hybrid beam antenna, and ensures that the signal transmission of the high-frequency antenna array is not affected at a small installation distance, thereby maintaining the radiation performance of the high-frequency antenna array itself. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a top view of a low-scattering hybrid beam antenna array provided by an embodiment of the present invention.

[0039] Figure 2 Schematic diagram of the structure of the antenna radiator of the low-scattering antenna unit in an embodiment of the present invention.

[0040] Figure 3 3 is a comparison diagram of the front and back structures of the first feed balun of the low-scattering antenna unit in an embodiment of the present invention.

[0041] Figure 4 3 is a comparison diagram of the front and back structures of the second feed balun of the low-scattering antenna unit in an embodiment of the present invention.

[0042] Figure 5 This is a current distribution diagram of the antenna radiator of the low-scattering antenna unit in an embodiment of the present invention when the high-frequency antenna array is excited.

[0043] Figure 6 3 is a structural comparison diagram of three comparative examples provided in the embodiments of the present invention.

[0044] Figure 7 yes Figure 6 The radiation performance comparison diagram of the antenna arrays of the three comparative examples is shown in FIG.

[0045] Figure 8 This is a schematic diagram of the bottom structure of a low-scattering hybrid beam antenna array provided by an embodiment of the present invention.

[0046] Figure 9 Schematic diagram of the front and back structures of the Butler matrix in an embodiment of the present invention.

[0047] Figure 10 Schematic diagram of the structure of the high-frequency power splitter unit in an embodiment of the present invention.

[0048] Figure 11 This is the radiation pattern of a low-scattering hybrid beam antenna array at 0.8 GHz provided by an embodiment of the present invention.

[0049] Figure 12This is a radiation pattern of a low-scattering hybrid beam antenna array at 1.94 GHz provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0050] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0051] like Figure 1 As shown, an embodiment of the present invention provides a low-scattering hybrid beam antenna array, which includes a reflector 1, a low-frequency antenna array, a high-frequency antenna array and a feeding network.

[0052] The low-frequency antenna array and the high-frequency antenna array are mixedly arranged above the reflector 1, and the feeding network is installed below the reflector 1; the feeding network feeds the low-frequency antenna array and the high-frequency antenna array respectively, so that the low-frequency antenna array and the high-frequency antenna array are both arranged on the reflector in a ±45° dual-polarization manner.

[0053] The high-frequency antenna array includes a first high-frequency antenna subarray 21, a second high-frequency antenna subarray 22, a third high-frequency antenna subarray 23 and a fourth high-frequency antenna subarray 24 arranged in parallel and side by side along the Y-axis direction, and each high-frequency antenna subarray includes four high-frequency antenna units arranged at equal intervals along the X-axis direction.

[0054] The low-frequency antenna array includes two low-scattering antenna units 11 arranged along the X-axis direction; the two low-scattering antenna units 11 are arranged between the second high-frequency antenna subarray 22 and the third high-frequency antenna subarray 23 in the Y-axis direction; in the X-axis direction, one of the low-scattering antenna units 11 is arranged between the first two high-frequency antenna units of the high-frequency antenna subarray, and the other low-scattering antenna unit 11 is arranged between the last two high-frequency antenna units of the high-frequency antenna subarray.

[0055] Combine Figures 2 to 4 As shown, the low-scattering antenna unit 11 includes a first dielectric plate 12, an antenna radiator, a first feeding balun and a second feeding balun.

[0056] The antenna radiator includes four radiating arms printed on the upper surface of the first dielectric plate 12. The four radiating arms are symmetrically distributed along the circumference of the first dielectric plate 12 with a 90° interval. Figure 2As shown in the figure, in the counterclockwise direction, there are first radiating arm 131, second radiating arm 132, third radiating arm 133, and fourth radiating arm 134. The first radiating arm 131 and the third radiating arm 133, which are arranged 180° apart from each other, form a first half-wave dipole, and the second radiating arm 132 and the fourth radiating arm 134, which are arranged 180° apart from each other, form a second half-wave dipole. The two half-wave dipoles are fed by the first feeding balun and the second feeding balun, respectively, to form dual-polarized radiation.

[0057] The four radiating arms have the same shape and structure. Figure 2 Taking the fourth radiating arm 134 shown in the figure as an example, the shape of a single radiating arm is generally square. Each radiating arm includes four L-shaped metal patches 135 respectively arranged at the four corners of the square and a parasitic patch 136 arranged at the center of the square. Each adjacent two L-shaped metal patches 135 are connected by a U-shaped branch 137; the width of the U-shaped branch 137 is smaller than the width of the L-shaped metal patch 135, and the total length of the U-shaped branch 137 is one-quarter wavelength of the operating center frequency of the high-frequency antenna array. The bottom of the U-shaped branch 137 is arranged toward the parasitic patch 136, the opening of the U-shaped branch 137 is arranged toward the outside of the radiating arm, and the two ends of the U-shaped branch 137 are respectively connected to the L-shaped metal patches 135 on both sides. In this embodiment, the width ratio of the U-shaped branch 137 to the L-shaped metal patch 135 is approximately 1:6.

[0058] like Figure 3 As shown, the first feeding balun includes a first feeding balun dielectric plate 141, a first microstrip transmission line 142, a first slot transmission line 143 and a first coupling feeding point 144; the first microstrip transmission line 142 is printed on the front surface of the first feeding balun dielectric plate 141; a metal patch is printed on each of the left and right halves of the back surface of the first feeding balun dielectric plate 141, and the two metal patches are spaced a certain distance apart to form a first slot transmission line 143 extending in a vertical direction in the middle of the back surface of the first feeding balun dielectric plate 141; the projections of the first microstrip transmission line 142 and the first slot transmission line 143 on the first feeding balun dielectric plate 141 partially overlap, forming a first coupling feeding point 144;

[0059] The upper end of the first feed balun dielectric plate 141 is vertically plugged into the first dielectric plate 12. The upper ends of the two metal patches on the back of the first feed balun dielectric plate 141 pass through the first dielectric plate 12 and are respectively welded to the first radiating arm 131 and the third radiating arm 133 that constitute the first half-wave oscillator. The plug-in and welding points are located at the corners of the L-shaped metal patches 135 in the first radiating arm 131 and the third radiating arm 133 that face the center of the first dielectric plate 12. The lower end of one of the metal patches is electrically connected to the outer conductor of the first coaxial cable. The inner conductor of the first coaxial cable passes through the first feed balun dielectric plate 141 and is electrically connected to the first microstrip transmission line 142.

[0060] like Figure 4 As shown, the second feeding balun includes a second feeding balun dielectric plate 151, a second microstrip transmission line 152, a second slot transmission line 153, and a second coupling feeding point 154; the second microstrip transmission line 152 is printed on the front surface of the second feeding balun dielectric plate 151; a metal patch is printed on each of the left and right halves of the back surface of the second feeding balun dielectric plate 151, and the two metal patches are spaced a certain distance apart to form a second slot transmission line 153 extending in a vertical direction in the middle of the back surface of the second feeding balun dielectric plate 151; the projections of the second microstrip transmission line 152 and the second slot transmission line 153 on the second feeding balun dielectric plate 151 partially overlap, forming a second coupling feeding point 154;

[0061] The upper end of the second feed balun dielectric plate 151 is vertically connected to the first dielectric plate 12. The upper ends of the two metal patches on the back of the second feed balun dielectric plate 151 pass through the first dielectric plate 12 and are respectively welded to the second radiating arm 132 and the fourth radiating arm 134 that constitute the second half-wave oscillator. The connection and welding points are located at the corners of the L-shaped metal patch 135 in the second radiating arm 132 and the fourth radiating arm 134 that faces the center of the first dielectric plate 12. The lower end of one of the metal patches is electrically connected to the outer conductor of the second coaxial cable. The inner conductor of the second coaxial cable passes through the second feed balun dielectric plate 151 and is electrically connected to the second microstrip transmission line 152.

[0062] Furthermore, a slot opening upward is provided above the middle of the first feed balun dielectric plate 141, and a slot opening downward is provided below the middle of the second feed balun dielectric plate 151; the first feed balun dielectric plate 141 and the second feed balun dielectric plate 151 are plugged into each other through the slots in the middle, so that the first feed balun and the second feed balun are vertically cross-connected to each other.

[0063] As an improvement, a complementary circular groove 16 is etched on each of the two metal patches on the back of the first feed balun dielectric plate 141, and a complementary circular groove 16 is also etched on each of the two metal patches on the back of the second feed balun dielectric plate 151. The complementary circular grooves 16 on the first feed balun dielectric plate 141 and the second feed balun dielectric plate 151 are located at the same height. The complementary circular grooves 16 include two concentrically nested circular arc grooves, with the inner circular arc groove opening facing upward and the outer circular arc groove opening facing downward. The total length of the circular arc grooves is approximately one-quarter wavelength of the operating center frequency of the high-frequency antenna array.

[0064] In the low-scattering antenna unit 11, the gradient structure between the U-shaped branch 137 and the L-shaped metal patch 135 on the radiating arm effectively produces a low-pass filtering effect. Simultaneously, the current flowing through the edges of the U-shaped branch 137 and the parasitic patch 136 effectively cancels out the high-frequency coupling currents from the high-frequency antenna array, achieving low-scattering characteristics. Furthermore, by etching complementary circular grooves 16 on the first and second feed baluns, a low-pass filtering effect can also be achieved, reducing the impact of high-frequency coupling currents and improving the isolation between the ports of the inter-frequency antenna units.

[0065] like Figure 5 As shown, when the same polarization of the high-frequency antenna array is simultaneously excited, it can be seen that a large amount of coupling current from the high-frequency antenna unit is concentrated near the U-shaped branch 137 on the surface of the antenna radiator of the low-scattering antenna unit 11. The current amplitudes on both sides of the U-shaped branch 137 are equal but the directions are opposite. At the same time, the current near the edge of the parasitic patch 136 is also opposite to the current in the middle part (bottom) of the U-shaped branch 137, thereby successfully achieving mutual cancellation of the high-frequency coupling currents.

[0066] In order to verify the low scattering characteristics of the low scattering antenna unit 11 in the embodiment of the present invention, Figure 6 Three antenna arrays with different distributions are presented for comparison. Comparative Example 1 is a high-frequency antenna array without any low-frequency antenna elements, Comparative Example 2 is a multi-frequency antenna array equipped with the low-scattering antenna elements 11 according to an embodiment of the present invention, and Comparative Example 3 is a multi-frequency antenna array containing conventional ring-shaped low-frequency antenna elements. During the comparative experiments, the third column of high-frequency antenna elements in all three comparative examples was fed with co-polarization, and the radiation patterns of the three were obtained.

[0067] like Figure 7As shown in the figure, a comparison of the radiation patterns of the three comparative examples at two frequency points is given. As can be seen from the figure, the pattern of comparative example 2 is almost the same as that of comparative example 1, while the pattern of comparative example 3 has obvious pattern distortion. This shows that the low-scattering antenna unit 11 in the embodiment of the present invention has low-scattering characteristics; when the low-frequency antenna array composed of the low-scattering antenna unit 11 in the embodiment of the present invention is used to form a hybrid beam antenna array with a high-frequency antenna array, the impact on the radiation pattern is small, and a good conformal effect is achieved on the antenna radiation pattern.

[0068] like Figure 8 As shown, the feeding network includes a low-frequency power splitting unit 3, a first high-frequency power splitting unit 41, a second high-frequency power splitting unit 42, a third high-frequency power splitting unit 43, a fourth high-frequency power splitting unit 44, a first Butler matrix 51 and a second Butler matrix 52.

[0069] The low-frequency power splitter unit 3 is connected to the low-frequency antenna array via a coaxial cable and is used to transmit a feed signal to the low-frequency antenna array. The input terminals of the first Butler matrix 51 and the second Butler matrix 52 are respectively connected to an external feed power source. The output terminal of the first Butler matrix 51 outputs a +45° polarized signal, and the output terminal of the second Butler matrix 52 outputs a -45° polarized signal. The beamforming of the high-frequency antenna array is achieved by the phase difference between the output ports of the two Butler matrices.

[0070] Combine Figure 9 As shown, the first Butler matrix 51 has a first output end, a second output end, a third output end, and a fourth output end, and the second Butler matrix 52 also has a first output end, a second output end, a third output end, and a fourth output end. The first output end of the first Butler matrix 51 and the first output end of the second Butler matrix 52 are fed to the first high-frequency antenna subarray 21 through the first high-frequency power splitter unit 41, the second output end of the first Butler matrix 51 and the second output end of the second Butler matrix 52 are fed to the second high-frequency antenna subarray 22 through the second high-frequency power splitter unit 42, the third output end of the first Butler matrix 51 and the third output end of the second Butler matrix 52 are fed to the third high-frequency antenna subarray 23 through the third high-frequency power splitter unit 43, and the fourth output end of the first Butler matrix 51 and the fourth output end of the second Butler matrix 52 are fed to the fourth high-frequency antenna subarray 24 through the fourth high-frequency power splitter unit 44, thereby achieving ±45° dual polarization of the high-frequency antenna units;

[0071] In order to reduce the influence of side lobes in the high-frequency antenna array, the signal ratio of the first output end, the second output end, the third output end and the fourth output end of the first Butler matrix 51 is 1:2:2:1, and the signal ratio of the first output end, the second output end, the third output end and the fourth output end of the second Butler matrix 52 is also 1:2:2:1.

[0072] Specifically, if Figure 9 As shown, the first Butler matrix 51 and the second Butler matrix 52 have the same structure, and each Butler matrix includes a Butler matrix dielectric plate 500 and a first directional coupler 501, a second directional coupler 502, a third directional coupler 503, a fourth directional coupler 504, a first 45° phase shifter 505, a second 45° phase shifter 506, a first one-to-two power splitter 507 and a second one-to-two power splitter 508 printed on the Butler matrix dielectric plate 500.

[0073] The input ends of the first directional coupler 501 and the second directional coupler 502 serve as the input ends of the Butler matrix, specifically including a first input end 511, a second input end 512, a third input end 513, and a fourth input end 514. The four input ends are connected to an external feeder via a coaxial cable. The output ends of the first directional coupler 501 and the second directional coupler 502 are connected to the input ends of the third directional coupler 503 and the fourth directional coupler 504 via a first 45° phase shifter 505 and a second 45° phase shifter 506. The cross line portion between the two 45° phase shifters is connected on the back side of the Butler matrix dielectric board 500 using a coaxial cable instead of a microstrip structure to improve the isolation of the beamforming network.

[0074] One output end of the third directional coupler 503 is connected to the input end of the first one-to-two power splitter 507, one output end of the first one-to-two power splitter 507 is connected to the first output end 521 of the Butler matrix, and the other output end of the first one-to-two power splitter 507 is welded to the first ohmic resistor 509 and then grounded to achieve signal diversion; another output end of the third directional coupler 503 is connected to the second output end 522 of the Butler matrix; one output end of the fourth directional coupler 504 is connected to the third output end 523 of the Butler matrix; another output end of the fourth directional coupler 504 is connected to the third output end 524 of the Butler matrix; It is connected to the input end of the second one-to-two power divider 508, one output end of the second one-to-two power divider 508 is connected to the fourth output end 524 of the Butler matrix, and the other output end of the second one-to-two power divider 508 is welded to the second ohmic resistor 510 and then grounded to achieve signal diversion; through the first one-to-two power divider 507 and the second one-to-two power divider 508, the signal ratio of the first output end 521, the second output end 522, the third output end 523 and the fourth output end 524 of the Butler matrix is ​​adjusted to 1:2:2:1, so as to effectively reduce the sidelobe level of the high-frequency antenna array.

[0075] In the two Butler matrices, through directional couplers with fixed 90-degree shift characteristics and 45-degree phase shifters, when a signal is input at the first input port 511, the four output ports 521, 522, 523, and 524 can output signals with a fixed -45-degree phase difference. When a signal is input at the second input port 512, the four output ports 521, 522, 523, and 524 can output signals with a fixed +135-degree phase difference. When a signal is input at the third input port 513, the four output ports 521, 522, 523, and 524 can output signals with a fixed -135-degree phase difference. When a signal is input at the fourth input port 514, the four output ports 521, 522, 523, and 524 can output signals with a fixed +45-degree phase difference. During power feeding, the corresponding input port is selected based on actual needs to achieve a phase difference between the output ports of the two Butler matrices, thereby achieving beamforming for the high-frequency antenna array.

[0076] Furthermore, the first high-frequency power splitting unit 41, the second high-frequency power splitting unit 42, the third high-frequency power splitting unit 43 and the fourth high-frequency power splitting unit 44 have the same structure. Figure 10 As shown, each high-frequency power splitter unit includes a first one-to-four power splitter 401 and a second one-to-four power splitter 402 , and the structures of the first one-to-four power splitter 401 and the second one-to-four power splitter 402 are completely the same.

[0077] The input end of the first one-to-four power divider 401 is connected to the first Butler matrix 51, and the four output ends of the first one-to-four power divider 401 are respectively connected to the +45° polarization direction balun feed of the four high-frequency antenna units in the corresponding high-frequency antenna subarray; the input end of the second one-to-four power divider 402 is connected to the second Butler matrix 52, and the four output ends of the second one-to-four power divider 402 are respectively connected to the -45° polarization direction balun feed of the four high-frequency antenna units in the corresponding high-frequency antenna subarray.

[0078] Based on the above antenna array structure, the embodiment of the present invention designs a low-scattering hybrid beam antenna array operating at 0.698-0.96GHz and 1.71-2.17GHz, with relative impedance bandwidths of 31.6% and 23.7% respectively. Figure 11 and Figure 12 As shown, the antenna array of the embodiment of the present invention achieves wide beam coverage at 0.698-0.96 GHz and four-beam radiation at 1.71-2.17 GHz, and the entire antenna array achieves good hybrid beam radiation performance.

[0079] The present invention provides a low-scattering hybrid beam antenna array that utilizes improved low-scattering antenna units to form a low-frequency antenna array. These low-scattering antenna units, based on a conventional ring structure, incorporate parasitic patches and U-shaped branches with a total length roughly corresponding to one-quarter the wavelength of the high-frequency antenna unit's operating center frequency. When the high-frequency antenna array is operating, the tapered width structure on the radiating arms of the low-scattering antenna units effectively produces a low-pass filtering effect. Simultaneously, coupling currents from the high frequency are concentrated on the edges of the U-shaped branches and parasitic patches, offsetting each other and reducing the coupling effect between different antennas. This ensures a conformal radiation pattern and achieves low-scattering characteristics.

[0080] In addition, the present invention also realizes unequal power distribution of the signals of the four output ports of the Butler matrix of the present invention by connecting a power divider to the output end of the traditional Butler matrix, thereby reducing the level of the side lobes of the radiation pattern of the high-frequency antenna array and improving the radiation performance of the antenna array.

[0081] The present invention provides a low-scattering hybrid beam antenna array, which achieves low-scattering characteristics only by improving the antenna unit structure itself. It has the characteristics of compact structure and does not require the addition of additional components. While meeting regional coverage and solving the problem of insufficient capacity, it effectively reduces the installation space required for the hybrid beam antenna, and ensures that the signal transmission of the high-frequency antenna array is not affected at a small installation distance, thereby maintaining the radiation performance of the high-frequency antenna array itself.

[0082] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A low-scattering hybrid beam antenna array, characterized in that: Including reflector, low frequency antenna array, high frequency antenna array and feeding network; The low-frequency antenna array and the high-frequency antenna array are arranged in a mixed manner, and the feeding network is installed below the reflector; the feeding network feeds the low-frequency antenna array and the high-frequency antenna array respectively, so that the low-frequency antenna array and the high-frequency antenna array are both arranged on the reflector in a ±45° dual-polarization manner; The low-frequency antenna array includes a plurality of low-scattering antenna units; the low-scattering antenna units include a first dielectric plate, an antenna radiator, a first feed balun and a second feed balun; The antenna radiator includes four radiating arms printed on the upper surface of a first dielectric plate. The four radiating arms are rotationally symmetrically distributed along the circumference with the center of the first dielectric plate as the center of the circle and at intervals of 90 degrees. Two of the radiating arms arranged opposite to each other constitute a first half-wave dipole, and the other two radiating arms arranged opposite to each other constitute a second half-wave dipole. The two half-wave dipoles are fed respectively by a first feeding balun and a second feeding balun to form dual-polarized radiation. The four radiating arms have the same shape and structure; the shape of a single radiating arm is a square as a whole, and each radiating arm includes four L-shaped metal patches respectively arranged at the four corners of the square and a parasitic patch arranged at the center of the square, and each adjacent two L-shaped metal patches are connected by a U-shaped branch; the width of the U-shaped branch is smaller than the width of the L-shaped metal patch, and the total length of the U-shaped branch is one-quarter wavelength of the working center frequency of the high-frequency antenna array.

2. The low-scattering hybrid beam antenna array according to claim 1, characterized in that: In the low-scattering antenna unit, the bottom of the U-shaped branch is arranged toward the parasitic patch, the opening of the U-shaped branch is arranged toward the outside of the radiation arm, and both ends of the U-shaped branch are respectively connected to the L-shaped metal patches on both sides.

3. The low-scattering hybrid beam antenna array according to claim 2, characterized in that: In the low-scattering antenna unit, the first feed balun and the second feed balun are vertically cross-connected to each other; Two complementary circular grooves are etched on the metal patches of the first feed balun and the second feed balun; the complementary circular grooves include two concentrically nested arc-shaped grooves, wherein the opening of the inner arc-shaped groove is set upward, and the opening of the outer arc-shaped groove is set downward.

4. The low-scattering hybrid beam antenna array according to claim 3, characterized in that: In the low-scattering antenna unit, the first feed balun includes a first feed balun dielectric plate, a first microstrip transmission line, a first slot transmission line, and a first coupling feed point; the first microstrip transmission line is printed on the front surface of the first feed balun dielectric plate; a metal patch is printed on each of the left and right halves of the back surface of the first feed balun dielectric plate, with a certain distance between the two metal patches to form a first slot transmission line extending in a vertical direction in the middle of the back surface of the first feed balun dielectric plate; the projections of the first microstrip transmission line and the first slot transmission line on the first feed balun dielectric plate partially overlap to form a first coupling feed point; The upper end of the first feed balun dielectric plate is vertically plugged into the first dielectric plate. The upper ends of the two metal patches on the back of the first feed balun dielectric plate pass through the first dielectric plate and are respectively welded to the two radiating arms constituting the first half-wave dipole. The lower end of one of the metal patches is electrically connected to the outer conductor of the first coaxial cable. The inner conductor of the first coaxial cable passes through the first feed balun dielectric plate and is electrically connected to the first microstrip transmission line. The second feed balun includes a second feed balun dielectric plate, a second microstrip transmission line, a second slot transmission line, and a second coupling feed point; the second microstrip transmission line is printed on the front surface of the second feed balun dielectric plate; a metal patch is printed on each of the left and right halves of the back surface of the second feed balun dielectric plate, and the two metal patches are spaced a certain distance apart to form a second slot transmission line extending in a vertical direction in the middle of the back surface of the second feed balun dielectric plate; the projections of the second microstrip transmission line and the second slot transmission line on the second feed balun dielectric plate partially overlap to form a second coupling feed point; The upper end of the second feed balun dielectric plate is vertically plugged into the first dielectric plate, the upper ends of the two metal patches on the back side of the second feed balun dielectric plate pass through the first dielectric plate and are respectively welded to the two radiating arms constituting the second half-wave dipole, the lower end of one of the metal patches is electrically connected to the outer conductor of the second coaxial cable, and the inner conductor of the second coaxial cable passes through the second feed balun dielectric plate and is electrically connected to the second microstrip transmission line; A complementary circular groove is etched on each of the two metal patches on the back of the first feed balun dielectric plate, and a complementary circular groove is also etched on each of the two metal patches on the back of the second feed balun dielectric plate; the complementary circular grooves on the first feed balun dielectric plate and the second feed balun dielectric plate are located at the same height.

5. The low-scattering hybrid beam antenna array according to claim 4, characterized in that: In the low-scattering antenna unit, a slot opening upward is provided above the middle of the first feed balun dielectric board, and a slot opening downward is provided below the middle of the second feed balun dielectric board; the first feed balun dielectric board and the second feed balun dielectric board are plugged into each other through the slot in the middle, so that the first feed balun and the second feed balun are vertically cross-connected to each other.

6. The low-scattering hybrid beam antenna array according to claim 4, characterized in that: In the low-scattering antenna unit, the welding points between the two metal patches on the back of the first feed balun dielectric plate and the two metal patches on the back of the second feed balun dielectric plate and the radiating arm are located at the corners of the L-shaped metal patch of the radiating arm toward the center of the first dielectric plate.

7. The low-scattering hybrid beam antenna array according to claim 1, characterized in that: The high-frequency antenna array includes a first high-frequency antenna subarray, a second high-frequency antenna subarray, a third high-frequency antenna subarray, and a fourth high-frequency antenna subarray, which are sequentially arranged in parallel along the Y-axis direction, and each high-frequency antenna subarray includes four high-frequency antenna units arranged at equal intervals along the X-axis direction; The low-frequency antenna array includes two low-scattering antenna units arranged along the X-axis direction; the two low-scattering antenna units are arranged between the second high-frequency antenna subarray and the third high-frequency antenna subarray in the Y-axis direction; in the X-axis direction, one of the low-scattering antenna units is arranged between the first two high-frequency antenna units of the high-frequency antenna subarray, and the other low-scattering antenna unit is arranged between the last two high-frequency antenna units of the high-frequency antenna subarray.

8. The low-scattering hybrid beam antenna array according to claim 7, characterized in that: The feeding network includes a low-frequency power splitting unit, a first high-frequency power splitting unit, a second high-frequency power splitting unit, a third high-frequency power splitting unit, a fourth high-frequency power splitting unit, a first Butler matrix and a second Butler matrix; The low-frequency power splitter unit is connected to the low-frequency antenna array and is used to transmit a feed signal to the low-frequency antenna array; The input ends of the first Butler matrix and the second Butler matrix are respectively connected to an external power supply, the output end of the first Butler matrix outputs a +45° polarized signal, and the output end of the second Butler matrix outputs a -45° polarized signal; The first Butler matrix has a first output terminal, a second output terminal, a third output terminal and a fourth output terminal, and the second Butler matrix also has a first output terminal, a second output terminal, a third output terminal and a fourth output terminal; The first output end of the first Butler matrix and the first output end of the second Butler matrix are fed to the first high-frequency antenna subarray through the first high-frequency power splitting unit, the second output end of the first Butler matrix and the second output end of the second Butler matrix are fed to the second high-frequency antenna subarray through the second high-frequency power splitting unit, the third output end of the first Butler matrix and the third output end of the second Butler matrix are fed to the third high-frequency antenna subarray through the third high-frequency power splitting unit, and the fourth output end of the first Butler matrix and the fourth output end of the second Butler matrix are fed to the fourth high-frequency antenna subarray through the fourth high-frequency power splitting unit, thereby realizing ±45° dual polarization of the high-frequency antenna unit; Among them, the signal ratio of the first output end, the second output end, the third output end and the fourth output end of the first Butler matrix is ​​1:2:2:1, and the signal ratio of the first output end, the second output end, the third output end and the fourth output end of the second Butler matrix is ​​1:2:2:

1.

9. The low-scattering hybrid beam antenna array according to claim 8, characterized in that: The first Butler matrix and the second Butler matrix have the same structure, and respectively include a Butler matrix dielectric plate and a first directional coupler, a second directional coupler, a third directional coupler, a fourth directional coupler, a first 45° phase shifter, a second 45° phase shifter, a first one-to-two power splitter, and a second one-to-two power splitter printed on the Butler matrix dielectric plate; The input ends of the first directional coupler and the second directional coupler serve as the input ends of the Butler matrix and are connected to an external feed power source through a coaxial cable for power supply; the output ends of the first directional coupler and the second directional coupler are connected to the input ends of the third directional coupler and the fourth directional coupler through a first 45° phase shifter and a second 45° phase shifter; One output end of the third directional coupler is connected to the input end of the first one-to-two power splitter, one output end of the first one-to-two power splitter is connected to the first output end of the Butler matrix, and the other output end of the first one-to-two power splitter is welded to the first ohm resistor and then grounded to achieve signal diversion; the other output end of the third directional coupler is connected to the second output end of the Butler matrix; one output end of the fourth directional coupler is connected to the third output end of the Butler matrix; the other output end of the fourth directional coupler is connected to the input end of the second one-to-two power splitter, one output end of the second one-to-two power splitter is connected to the fourth output end of the Butler matrix, and the other output end of the second one-to-two power splitter is welded to the second ohm resistor and then grounded to achieve signal diversion; through the first one-to-two power splitter and the second one-to-two power splitter, the signal ratio of the first output end, the second output end, the third output end and the fourth output end of the Butler matrix is ​​1:2:2:

1.

10. The low-scattering hybrid beam antenna array according to claim 9, characterized in that: The first high-frequency power splitting unit, the second high-frequency power splitting unit, the third high-frequency power splitting unit and the fourth high-frequency power splitting unit have the same structure; each high-frequency power splitting unit includes a first one-to-four power splitter and a second one-to-four power splitter; An input end of the first one-to-four power divider is connected to the first Butler matrix, and four output ends of the first one-to-four power divider are respectively connected to the +45° polarization direction balun feeds of the four high-frequency antenna units in the corresponding high-frequency antenna subarray; The input end of the second one-to-four power divider is connected to the second Butler matrix, and the four output ends of the second one-to-four power divider are respectively connected to the -45° polarization direction balun feed of the four high-frequency antenna units in the corresponding high-frequency antenna subarray.

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