Spherical conformal transmission array for two-dimensional beam scanning

Abstract

The invention discloses a beam two-dimensional scanning spherical conformal transmission array, and belongs to the field of emergency communication of millimeter wave frequency bands, the beam two-dimensional scanning spherical conformal transmission array comprises a spherical conformal 3D printing spherical shell carrier, the surface of the 3D printing spherical shell carrier is inlaid with a plurality of plane transmission sub-arrays distributed according to longitude and latitude, each plane transmission sub-array comprises cross dipole FSS units arranged periodically, and the cross dipole FSS units are embedded in the surface of the 3D printing spherical shell carrier. The radiation phases of the FSS units of the transmission array are ensured to be superposed in the target direction by calculating the space phase delay compensation amount; a millimeter wave feed source antenna is arranged below the 3D printing spherical shell carrier, different plane transmission sub-arrays are irradiated by rotating a millimeter wave feed source, and beam forming and control are achieved in combination with phase compensation. The spherical conformal transmission array for two-dimensional beam scanning has the characteristics of high gain, large bandwidth and two-dimensional beam scanning, thereby providing stable and high-speed data transmission capability in emergency communication and other scenes.

Description

Technical Field

[0001] The present invention relates to the technical field of emergency communication in a millimeter wave frequency band, and in particular to a spherical conformal transmission array for two-dimensional beam scanning. Background Art

[0002] When natural disasters and other unexpected events occur, the communication network at the scene may be damaged or even completely destroyed, resulting in communication paralysis, loss of personnel contact and other problems. In the millimeter wave frequency band, the use of drones equipped with spherical conformal transmission array antennas has the characteristics of high gain and large bandwidth, and is therefore widely used. However, traditional transmission array antennas have the following defects: 1. Narrow beam width: The coverage is limited and it is difficult to meet the needs of dynamic scenarios (such as high-speed movement of drones); 2. Large scanning loss: The existing beam scanning method is prone to introduce phase errors during two-dimensional scanning, resulting in a decrease in gain; 3. Structural limitations: Planar antennas are difficult to conform to curved carriers (such as drone fuselages), which affects system integration. Summary of the invention

[0003] The purpose of the present invention is to provide a spherical conformal transmission array for two-dimensional beam scanning to solve the above technical problems.

[0004] To achieve the above-mentioned object, the present invention provides a spherical conformal transmission array for beam two-dimensional scanning, comprising a spherical conformal 3D printed spherical shell carrier, the surface of which is inlaid with a plurality of planar transmission sub-arrays distributed in longitude and latitude, each planar transmission sub-array comprising periodically arranged cross-dipole FSS units, and by calculating the spatial phase delay compensation amount, ensuring that the radiation phases of the FSS units of the transmission array are superimposed in the target direction; A millimeter-wave feed antenna is set under the 3D printed spherical shell carrier. The millimeter-wave feed is rotated to illuminate different planar transmission sub-arrays, and beam synthesis and control are achieved in combination with phase compensation.

[0005] Preferably, it is assumed that the plane transmission subarray located at the center of the spherical surface of the 3D printed spherical shell carrier is the central plane transmission subarray, and the coordinates of the remaining plane transmission subarrays are obtained by rotating the Rodrigues rotation formula to ensure that each transmission subarray is evenly and symmetrically distributed on the spherical surface; The center distance between two adjacent plane transmission subarrays , Indicates the operating wavelength.

[0006] Preferably, it is assumed that the period length of the planar transmission subarray is , then the coordinate expression of each cross-dipole FSS unit in the central plane transmission subarray is as follows: ; in, ; In the formula, represents the first Line The coordinates of the cross-dipole FSS unit of the column; , , They represent the first Line The X-axis, Y-axis, and Z-axis coordinates of the cross-dipole FSS unit of the column; represents the first Line The Z-axis coordinate value of the cross-dipole FSS unit in the column; The Rodrigues rotation formula rotates the coordinates of each cross-dipole FSS unit in the central plane transmission subarray around the direction vector Rotate to obtain the cross-dipole FSS unit coordinates of the corresponding positions on each plane transmission array after rotation: ; in, ; In the formula, Indicates Line The first row of the plane transmission subarray Line The coordinates of the cross-dipole FSS unit of the column; , , Respectively represent Line The first row of the plane transmission subarray Line The X-axis, Y-axis, and Z-axis coordinates of the cross-dipole FSS unit of the column; Indicates Line The rotation azimuth angle of the plane transmission sub-array of the column; Indicates Line The rotation angle of the plane transmission sub-array is , represents the distance between each plane transmission sub-array and the central plane transmission sub-array, .

[0007] Preferably, the cross-dipole FSS unit is a double-layer cross-shaped metal patch structure, and the patch size, layer spacing and dielectric substrate parameters meet the requirements of linear variation of transmission phase in the 28 GHz-32 GHz frequency band.

[0008] Preferably, the boundary of adjacent plane transmission subarrays uses MMSE method to compensate for phase mutation, and the quantized phase of the compensated plane transmission subarray is 3-bit; Length of the crossed-dipole FSS unit The transmission phase coverage range is 340° within the length range corresponding to a transmission loss of less than 3dB.

[0009] Preferably, the compensation phase of the cross-dipole FSS unit is: ; In the formula, Indicates Line The first Total phase compensation of row-crossed dipole FSS units; represents the spatial phase delay compensation amount with the cross-dipole FSS unit; Indicates Line The first row of the plane transmission subarray Line The cross-dipole FSS units of the columns are used to achieve the compensation phase of the corresponding beam pointing; Indicates Line The smoothed phase compensation value of the planar transmission subarray of the column; in, The calculation formula of spatial phase delay compensation is as follows: ; In the formula, Indicates Line The first row of the plane transmission subarray Line Phase compensation amount of the cross-dipole FSS unit in the column; represents the free space wave number; Indicates the center coordinates of the millimeter wave feed antenna With Line The first row of the plane transmission subarray Line The spatial distance of the cross-dipole FSS units of the column; , , Respectively represent the x-, y-, and z-axis coordinates of the center of the millimeter-wave feed antenna; ; In the formula, Indicates Line The elevation angle of the plane transmission subarray beam pointing in the array, and , represents the spatial radius of the central plane transmission subarray, Indicates Line The spatial radius of the plane transmission subarray of the column; Indicates Line The azimuth angle of the plane transmission subarray beam pointing to the , Indicates Line The component of the plane transmission subarray beam of the column in the longitudinal coordinate, Indicates Line The component of the plane transmission subarray beam of the column in the transverse coordinate; Since the spherical conformal transmission array is a two-dimensional symmetrical structure, the remaining plane transmission sub-array can be obtained by calculating a quarter of the plane transmission sub-array and then rotating it; The smooth phase compensation value of the planar transmission subarray is: ; ; In the formula, Indicates the 3rd row The smoothed phase compensation value of the planar transmission subarray of the column; Indicates the 3rd row The first row of the plane transmission subarray The cross-dipole FSS unit in the sixth row is to realize the compensation phase of the corresponding beam pointing; Indicates the 3rd row The first row of the plane transmission subarray The cross-dipole FSS unit in the first column of the row is to realize the compensation phase of the corresponding beam pointing; Indicates The plane transmission subarray of row 3 and column 6 The cross-dipole FSS units in the columns are used to achieve the compensation phase of the corresponding beam pointing; Indicates Line The sixth row of the plane transmission subarray of the column The cross-dipole FSS units in the columns are used to achieve the compensation phase of the corresponding beam pointing; Indicates Line The first row of the plane transmission subarray Line The cross-dipole FSS units in the columns are used to achieve the compensation phase of the corresponding beam pointing; Indicates Line The first row of the plane transmission subarray The cross-dipole FSS unit in the first column of the row is to realize the compensation phase of the corresponding beam pointing; Indicates Line The smoothed phase compensation value of the planar transmission subarray of the column; Indicates Line The sixth row of the plane transmission subarray of the column The cross-dipole FSS units in the columns are used to achieve the compensation phase of the corresponding beam pointing; Indicates Line The first row of the plane transmission subarray of the column The cross-dipole FSS units in the columns are used to achieve the compensation phase of the corresponding beam pointing; Indicates Line The smoothed phase compensation value of the planar transmission subarray of the series is: to achieve the compensation phase corresponding to the beam pointing, to achieve the compensation phase corresponding to the beam pointing, to achieve the compensation phase corresponding to the beam pointing.

[0010] Preferably, the dielectric thickness of the crossed-dipole FSS unit is set to , represents the electrical thickness, and , represents the dielectric constant; Indicates the dielectric thickness to obtain the maximum transmission phase range.

[0011] Preferably, the millimeter wave feed antenna includes multiple microstrip array antennas on the upper layer and a feeding network on the lower layer. A double-thin layer common ground isolation ring between the multiple microstrip array antennas on the upper layer and the feeding network isolates radiation, avoids antenna short circuit, and suppresses mutual coupling effect.

[0012] Preferably, each microstrip array antenna is connected in parallel with a feeding network to ensure radiation stability.

[0013] Preferably, the surface of the 3D printed spherical shell carrier is inlaid with 25 planar transmission subarrays, and each planar transmission subarray includes 6×6 cross-dipole FSS units.

[0014] Therefore, the present invention adopts the above-mentioned spherical conformal transmission array with two-dimensional beam scanning, which has the following beneficial effects: 1. Improved coverage: By continuously rotating the feed source to illuminate the corresponding transmission sub-array, the scheme achieves two-dimensional beam scanning. This greatly improves the coverage of the antenna, allowing effective communication connections to be maintained in complex terrain or disaster-stricken areas; 2. Beam scanning is more flexible and accurate: at least four sub-beams are used to synthesize a main beam with a desired direction, so that two-dimensional continuous beam control can be achieved by adjusting the direction of the sub-beams; 3. The FSS unit used is a cross-dipole patch with a stable transmission coefficient. Even when the incident angle increases to 45°, the maximum transmission loss is only 2dB, ensuring the overall stable and reliable performance of the transmission array; 4. By changing the size of the FSS unit to excite different resonant frequencies and obtain the required transmission phase, the transmission loss is less than 3dB and the transmission phase coverage range is about 340° in the corresponding length interval, meeting the 3-bit quantized phase requirement; 5. Directional beam and lightweight: The microstrip array antenna is used as the feed source to obtain a directional beam similar to a horn, while reducing the weight as much as possible, which is beneficial to the loading and endurance of carriers such as drones; at the same time, a double-thin layer common ground isolation ring is used to isolate the radiation unit and the feed network, avoiding the mutual coupling between the antenna and the feed network to deteriorate the radiation pattern, and ensuring the stability of the radiation performance of the feed antenna; 6. Phase compensation mechanism: By accurately calculating the phase compensation value of each FSS unit, the expected pointing of the beam is achieved, ensuring the beam scanning accuracy and coverage of the antenna system; 7. Subarray edge phase smoothing: Subarray edge phase smoothing technology is used to reduce phase mutations between subarrays, improve the shape of the radiation pattern, make the main lobe sharper, and significantly reduce the side lobes.

[0015] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A simulation structure diagram of a spherical conformal transmission array for two-dimensional beam scanning described in a simulation experiment of the present invention; Figure 2 This is a schematic diagram of the beam control principle described in the simulation experiment of the present invention; Figure 3The geometric diagram of the plane transmission subarray described in the simulation experiment of the present invention, wherein (a) is a distribution diagram of the plane transmission subarray; (b) is a schematic diagram of the internal composition of the plane transmission subarray; (c) is a schematic diagram of the three-dimensional structure of the plane transmission subarray; (d) is a schematic diagram of the rotation and position parameters of the plane transmission subarray; Figure 4 Schematic diagram of the structure of the cross-dipole FSS unit described in the simulation experiment of the present invention, wherein (a) is a top view of the cross-dipole FSS unit; (b) is a cross-sectional view of the cross-dipole FSS unit; Figure 5 The simulation results of the cross-dipole FSS unit described in the simulation experiment of the present invention are shown in FIG. (a) is a curve diagram showing the relationship between the transmission coefficient of the cross-dipole FSS unit and the frequency; (b) is a curve diagram showing the relationship between the transmission coefficient of the cross-dipole FSS unit and the length. The changing relationship curve diagram; Figure 6 The simulation result diagram of the cross-dipole FSS unit when the microstrip array antenna described in the simulation experiment of the present invention is used as the structure of the illumination feed source, wherein (a) is the layout diagram of the microstrip array antenna; (b) is the feeder structure design diagram; (c) is the cross-sectional view of the microstrip array antenna; Figure 7 Schematic diagram of beam pointing in the simulation experiment of the present invention, wherein (a) is the beam pointing distribution diagram of 25 transmission sub-arrays, and (b) is the principle diagram of beam pointing angle derivation in Cartesian coordinate system; Figure 8 This is a comparison diagram of the phase smoothing setting direction diagram described in the simulation experiment of the present invention; Fig. 9 The phase distribution diagram of the planar unfolded structure of the spherical conformal transmission array described in the simulation experiment of the present invention, wherein (a) is the phase distribution diagram before smoothing, and (b) is the phase distribution diagram after smoothing; Fig.10 The spherical conformal transmission array described in the simulation experiment of the present invention is different The simulation pattern below: Fig.11 Schematic diagram of two-dimensional beam scanning of spherical conformal transmission array described in the simulation experiment of the present invention, where (a) is the polarization angle or Time gain with viewing angle , (b) is the curve of the change of polarization angle or Time gain with viewing angle 's change curve graph. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical scheme and advantages disclosed in the embodiments of the present invention clearer, the embodiments of the present invention are further described in detail in combination with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the embodiments of the present invention and are not used to limit the embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions.

[0018] It should be noted that the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or server that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or inherent to these processes, methods, products or devices.

[0019] The embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0020] A spherical conformal transmission array for beam two-dimensional scanning, comprising a spherical conformal 3D printed spherical shell carrier, wherein the surface of the 3D printed spherical shell carrier is inlaid with a plurality of planar transmission sub-arrays distributed in longitude and latitude, each planar transmission sub-array comprises periodically arranged cross-dipole FSS units, and by calculating the spatial phase delay compensation amount, the radiation phase of each FSS unit (frequency selective surface unit) of the transmission array is ensured to be superimposed in the target direction; Specifically: The compensation phase of the crossed-dipole FSS unit is: ; In the formula, Indicates Line The first Total phase compensation of row-crossed dipole FSS units; represents the spatial phase delay compensation amount with the cross-dipole FSS unit; Indicates Line The first row of the plane transmission subarray Line The cross-dipole FSS units of the columns are used to achieve the compensation phase of the corresponding beam pointing; Indicates Line The smoothed phase compensation value of the planar transmission subarray of the column; in, The calculation formula of spatial phase delay compensation is as follows: ; In the formula, Indicates Line The first row of the plane transmission subarray Line Phase compensation amount of the cross-dipole FSS unit in the column; represents the free space wave number; Indicates the center coordinates of the millimeter wave feed antenna With Line The first row of the plane transmission subarray Line The spatial distance of the cross-dipole FSS units of the column; , , Respectively represent the x-, y-, and z-axis coordinates of the center of the millimeter-wave feed antenna; ; In the formula, Indicates Line The elevation angle of the plane transmission subarray beam pointing in the array, and , represents the spatial radius of the central plane transmission subarray, Indicates Line The spatial radius of the plane transmission subarray of the column, and , , , and Respectively represent the third row Column, No. The rotation and pitch angle of the 3-row plane transmission subarray; Indicates Line The azimuth angle of the plane transmission subarray beam pointing to the , Indicates Line The component of the plane transmission subarray beam of the column in the longitudinal coordinate, Indicates Line The component of the plane transmission subarray beam of the column in the transverse coordinate; Since the spherical conformal transmission array is a two-dimensional symmetrical structure, the calculation of the quarter plane transmission subarray (such as Figure 7 The remaining plane transmission sub-array can be obtained by rotating the selected one-quarter sub-array area. The smooth phase compensation value of the planar transmission subarray is: ; ; In the formula, Indicates the 3rd row The smoothed phase compensation value of the planar transmission subarray of the column; Indicates the 3rd row The first row of the plane transmission subarray The cross-dipole FSS unit in the sixth row is to realize the compensation phase of the corresponding beam pointing; Indicates the 3rd row The first row of the plane transmission subarray The cross-dipole FSS unit in the first column of the row is to realize the compensation phase of the corresponding beam pointing; Indicates The plane transmission subarray of row 3 and column 6 The cross-dipole FSS units in the columns are used to achieve the compensation phase of the corresponding beam pointing; Indicates Line The sixth row of the plane transmission subarray of the column The cross-dipole FSS units in the columns are used to achieve the compensation phase of the corresponding beam pointing; Indicates Line The first row of the plane transmission subarray Line The cross-dipole FSS units in the columns are used to achieve the compensation phase of the corresponding beam pointing; Indicates Line The first row of the plane transmission subarray The cross-dipole FSS unit in the first column of the row is to realize the compensation phase of the corresponding beam pointing; Indicates Line The smoothed phase compensation value of the planar transmission subarray of the column; Indicates Line The sixth row of the plane transmission subarray of the column The cross-dipole FSS units in the columns are used to achieve the compensation phase of the corresponding beam pointing; Indicates Line The first row of the plane transmission subarray of the column The cross-dipole FSS units in the columns are used to achieve the compensation phase of the corresponding beam pointing; Indicates Line The smoothed phase compensation value of the planar transmission subarray of the series is: to achieve the compensation phase corresponding to the beam pointing, to achieve the compensation phase corresponding to the beam pointing, to achieve the compensation phase corresponding to the beam pointing.

[0021] In this embodiment, the phase smoothing derivation process of the edges of two adjacent planar transmission sub-arrays is as follows: Assumptions , , expected beamforming direction , at this time, the phase difference , the array factors of the two sub-arrays are: ; ; Using Euler's formula, we can calculate the two subarrays in The amplitudes in the directions are: ; Thus, we can obtain Total amplitude in direction for: ; After simplification, we get: .

[0022] It can be seen that when the phase mutation value at the edge of the subarray The larger the value, the lower the amplitude of the synthesized main lobe. When the mutation value reaches a certain level, the main lobe disappears and is replaced by a null.

[0023] For transmission array antennas, although the feed source is radiating initially, according to Huygens principle, the FSS unit being irradiated can also be regarded as radiating itself as a secondary wave source. Therefore, the above derivation of edge phase mutation is still applicable to transmission array antennas.

[0024] A millimeter-wave feed antenna is set under the 3D printed spherical shell carrier. The millimeter-wave feed is rotated to illuminate different planar transmission sub-arrays, and beam synthesis and control are achieved in combination with phase compensation.

[0025] Assuming that the plane transmission subarray located at the center of the spherical surface of the 3D printed spherical shell carrier is the central plane transmission subarray, the coordinates of the remaining plane transmission subarrays are obtained by rotating them using the Rodrigues rotation formula to ensure that each transmission subarray is evenly and symmetrically distributed on the spherical surface; The center distance between two adjacent plane transmission subarrays , Indicates the operating wavelength.

[0026] At this time, it is assumed that the period length of the plane transmission subarray is , then the coordinate expression of each cross-dipole FSS unit in the central plane transmission subarray is as follows: ; in, ; In the formula, represents the first Line The coordinates of the cross-dipole FSS unit of the column; , , They represent the first Line The X-axis, Y-axis, and Z-axis coordinates of the cross-dipole FSS unit of the column; represents the first Line The Z-axis coordinate value of the cross-dipole FSS unit in the column; The Rodrigues rotation formula rotates the coordinates of each cross-dipole FSS unit in the central plane transmission subarray around the direction vector Rotate to obtain the cross-dipole FSS unit coordinates of the corresponding positions on each plane transmission array after rotation: ; Will as well as ( Indicates Line The rotation axis direction vector of the plane transmission sub-array of the column, and , , , and Respectively represent Line The projection coordinates of the center of the plane transmission subarray of the column in the xoy plane; represents the wave number;) Substitute into the above formula to get the coordinates of the cross-dipole FSS unit at the corresponding position on each plane transmission array after rotation: ; in, ; In the formula, Indicates Line The first row of the plane transmission subarray Line The coordinates of the cross-dipole FSS unit of the column; , , Respectively represent Line The first row of the plane transmission subarray Line The X-axis, Y-axis, and Z-axis coordinates of the cross-dipole FSS unit of the column; Indicates Line The rotation azimuth angle of the plane transmission sub-array of the column; Indicates Line The rotation angle of the plane transmission sub-array is , represents the distance between each plane transmission sub-array and the central plane transmission sub-array, .

[0027] The crossed-dipole FSS unit is a double-layer cross-shaped metal patch structure, and the patch size, layer spacing and dielectric substrate parameters meet the requirements of linear transmission phase change in the 28GHz-32GHz frequency band.

[0028] The MMSE method is used to compensate the phase mutation at the boundary of adjacent plane transmission subarrays. The quantized phase of the plane transmission subarray after compensation is 3-bit. The length of the cross-dipole FSS unit is The transmission phase coverage range is 340° within the length range corresponding to a transmission loss of less than 3dB.

[0029] The dielectric thickness of the crossed-dipole FSS unit is set to , represents the electrical thickness, and , represents the dielectric constant; Indicates the dielectric thickness to obtain the maximum transmission phase range.

[0030] The millimeter wave feed antenna includes multiple microstrip array antennas on the upper layer and a feeding network on the lower layer. A double-thin layer common ground isolation ring is used between the multiple microstrip array antennas on the upper layer and the feeding network to isolate radiation, avoid antenna short circuit, and suppress mutual coupling effects. Each microstrip array antenna is connected in parallel with the feeding network to ensure radiation stability.

[0031] The surface of the 3D printed spherical shell carrier is inlaid with 25 planar transmission subarrays, each of which contains 6×6 cross-dipole FSS units.

[0032] Simulation experiment As Figure 1 The spherical conformal transmission array with two-dimensional beam scanning is based on Figure 2 The beam control principle shown is explained as an example ( Figure 2In the figure, a33 is the central plane transmission subarray. It can be seen that in one-dimensional beam synthesis, two sub-beams can be synthesized into a new beam, and by adjusting the directions of the two sub-beams, the direction of the synthesized beam will also change accordingly. In two-dimensional beam synthesis, in order to achieve two-dimensional continuous beam control, at least four sub-beams must be used to synthesize a main beam with the expected direction, and the direction of the synthesized beam is approximately the pitch angle of each sub-beam. and azimuth The weighted mean of : ; In the formula, Respectively represent The elevation angle of each sub-beam; Indicates The azimuth of the sub-beam.

[0033] Based on the above principle, it can be known that by continuously rotating the feed source to illuminate the corresponding transmission sub-array, sub-beams with different directions can be generated, so that the expected highly directional beam can be synthesized; and in order to achieve two-dimensional and continuous beam scanning, the four transmission sub-arrays should be adjacent to each other. Therefore, the present invention adopts the topological structure of the spherical conformal transmission array, and adopts the following method: Figure 4 The cross-dipole FSS unit structure shown has the following dimensional parameters: period , Width , length , dielectric constant .

[0034] The simulation results of the cross-dipole FSS unit based on the above structure are as follows: Figure 5 As shown, it can be seen that the transmission phase of the cross-dipole FSS unit is still very stable when facing incident beams at different angles. And as the incident angle increases, the transmission amplitude has a certain attenuation at certain frequencies, but even if the incident angle increases to 45°, the maximum transmission loss is only 2dB, which is very critical to ensure the overall performance of the transmission array. And it can be seen that the cross-dipole FSS unit has different transmission phases at different frequencies, so different resonant frequencies can be excited by changing the size of the cross-dipole FSS unit to obtain the required transmission phase.

[0035] like Figure 6 As shown in the figure, when the microstrip array antenna is selected as the lighting feed structure, When , the transmission loss is less than 1.5dB. After that, the transmission loss increases sharply. When , the change of transmission phase is relatively flat. Therefore, considering the transmission loss and transmission phase as a compromise, The value is set between 2mm and 3.41mm. At this time, the transmission loss is less than 3dB and the transmission phase coverage range in the corresponding length interval is about 340°, which fully meets the 3-bit quantized phase requirement (3-bit quantized phase requires a phase coverage range of 315°).

[0036] In order to obtain a horn-like directional beam while reducing weight, the following Figure 6 shown The microstrip array antenna is used as the feed source. At the same time, as the feed source in the transmission array, a well-shaped symmetrical directional pattern is very important. Therefore, a double-thin layer common ground isolation ring is used to isolate the microstrip array antenna from the feeding network.

[0037] Based on the above structure, Figure 7 In the phase compensation simulation experiment shown in the figure, the central plane transmission subarray a33 beam is set to the +z axis ( , ). And in the two main coordinate axes of x and y ( , ) Set a certain elevation gradient. Considering the beam coverage and gain of the plane transmission subarray, the elevation step value on the two main planes is set to 10°. At this time, the beam pointing of other subarrays can be derived based on the existing beam angles on the two axes: ; In the formula, Indicates Line Beam pointing of the planar transmission subarray of the column; Indicates The beam pointing direction of the planar transmission subarray in the third row; Indicates the 3rd row Beam pointing of the planar transmission subarray of the column; Represents the beam pointing of the central plane transmission subarray And in Figure 7 In Figure (b), set the vector , , , Represent the directions of different sub-beams, and Respectively, vector and The length of the projection on the x-axis and the y-axis; now we get: ; This makes it easier to obtain the compensation phase for different beam pointing directions.

[0038] like Figure 8As shown in the figure, the sudden phase change at the edge of the plane transmission subarray causes the radiation pattern to deteriorate seriously. Therefore, in order to obtain a good radiation pattern, it is necessary to perform phase smoothing on the boundary of the plane transmission subarray. Since the phase of each plane transmission subarray is a relative value, the direction of the beam will not be affected as long as the phase between each FSS unit within it is not changed. Therefore, the effect of smooth transition of the edge phase between plane transmission subarrays can be achieved by adding or subtracting a certain value. Therefore, the central plane transmission subarray a33 is used as the initial reference subarray and then recursively extended to the peripheral plane transmission subarrays. First, each plane transmission subarray is compensated with a phase constant ,and , represents the compensation phase of the central plane transmission subarray a33 to achieve the corresponding beam pointing, Represents the phase constant.

[0039] Combination Figure 3 It can be seen that the plane transmission sub-array a23 and the plane transmission sub-array a32 are adjacent to the center plane transmission sub-array a33, so their calculation methods are basically the same. Taking a32 as an example, it contains FSS units, the 6th column in a32 is adjacent to the 1st column in a33 (the 6th row in a23 is adjacent to a33), and the MMSE method is used to traverse the boundary smoothing phase value of a32 ,get: ; In the formula, Indicates the first Directional phase value of the FSS unit in row column 6; Indicates the first Directional phase value of the FSS unit in row column 1; Reuse The smooth transition of the plane transmission sub-array phase can be obtained.

[0040] For the smoothed phase of the bilaterally adjacent planar transmission subarray, such as a22, its 6th row is adjacent to a32, and its 6th column is adjacent to a23. Therefore, based on the phase smoothing values ​​of a32 and a23, the phase smoothing value of a22 is calculated. :

[0041] In the formula, Indicates the first Directional phase value of the FSS unit in row column 6; Indicates the first Directional phase value of the FSS unit in row column 1; Indicates the sixth row in a22 Directional phase value of the FSS unit of the column; Indicates the first row of a22 Directional phase value of the FSS unit of the column; represents the boundary smoothing phase value of a23; Similarly, the phase smoothing value of all plane transmission sub-arrays can be solved, and the transmission array directivity diagram after smoothing is as follows: Figure 8 As shown by the solid line in the middle, it can be seen that the main lobe of the beam is sharper and the side lobes are greatly reduced.

[0042] In addition, considering the design complexity and antenna performance, a 3-bit quantized phase is used (i.e., a phase is taken every 45°, totaling 8 states). For the planar transmission subarray unfolded in the plane, the phase distribution before and after smoothing is as follows: Fig. 9 As shown in the figure, it can be seen that the unprocessed phase distribution is messy and irregular, especially for ( ) of the plane transmission subarray, compared with the phase distribution before smoothing, the phase transition after processing is smoother.

[0043] like Fig.10 As shown, for a spherical conformal transmission array, the projected spacing between antennas is Determine the rotation angle of the plane transmission subarray Then determine the radiation performance of the antenna, and get the simulation results as follows Fig.11 As shown, in order to ensure that the transmission sub-arrays on the spherical surface do not overlap, The value must be at least 2.52 (The side length of each plane transmission subarray is 2.4 ). At this time, the structure of the spherical conformal transmission array is the most compact and the gain reaches 20.9dBi. However, the spacing between the plane transmission sub-arrays is too small to be processed in real life. = 3 When the gap is 1 / 4, there is enough space to fill the 3D printing material as the overall support structure, but the larger gap will cause the pattern gain to decrease and the sidelobe level to increase (because the gap area cannot adjust the phase of the beam and the synthesized pattern sidelobe increases). In addition, when the feed beam irradiation area is constant, the increase in the gap area will lead to a decrease in the effective aperture of the synthesized expected beam, thereby reducing the gain of the main lobe of the pattern. Therefore, in order to balance the antenna performance and physical processing, the subarray spacing is adjusted to = 2.7 ,At this time, the antenna gain is about 20.2 dBi and the radiation pattern is in good shape, and the scanning loss is very small, achieving a good effect, thus proving the effectiveness of the present invention.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A spherical conformal transmission array with two-dimensional beam scanning, characterized in that: It includes a 3D printed spherical shell carrier that is conformal to the spherical surface. The surface of the 3D printed spherical shell carrier is inlaid with multiple plane transmission sub-arrays distributed in longitude and latitude. Each plane transmission sub-array contains periodically arranged cross-dipole FSS units. By calculating the spatial phase delay compensation amount, it is ensured that the radiation phase of each FSS unit of the transmission array is superimposed in the target direction. A millimeter-wave feed antenna is set under the 3D printed spherical shell carrier. The millimeter-wave feed is rotated to illuminate different planar transmission sub-arrays, and beam synthesis and control are achieved in combination with phase compensation.

2. The spherical conformal transmission array for two-dimensional beam scanning according to claim 1, characterized in that: Assuming that the plane transmission subarray located at the center of the spherical surface of the 3D printed spherical shell carrier is the central plane transmission subarray, the coordinates of the remaining plane transmission subarrays are obtained by rotating them using the Rodrigues rotation formula to ensure that each transmission subarray is evenly and symmetrically distributed on the spherical surface; The center distance between two adjacent plane transmission sub-arrays , Indicates the operating wavelength.

3. The spherical conformal transmission array for two-dimensional beam scanning according to claim 2, characterized in that: Assume that the period length of the plane transmission subarray is , then the coordinate expression of each cross-dipole FSS unit in the central plane transmission subarray is as follows: ； in, ； In the formula, represents the first Line The coordinates of the cross-dipole FSS unit of the column; , , They represent the first Line The X-axis, Y-axis, and Z-axis coordinates of the cross-dipole FSS unit of the column; represents the first Line The Z-axis coordinate value of the cross-dipole FSS unit in the column; The Rodrigues rotation formula rotates the coordinates of each cross-dipole FSS unit in the central plane transmission subarray around the direction vector Rotate to obtain the cross-dipole FSS unit coordinates of the corresponding positions on each plane transmission array after rotation: ； in, ； In the formula, Indicates Line The first Line The coordinates of the cross-dipole FSS unit of the column; , , Respectively represent Line The first Line The X-axis, Y-axis, and Z-axis coordinates of the cross-dipole FSS unit of the column; Indicates Line The rotation azimuth angle of the plane transmission sub-array of the column; Indicates Line The rotation angle of the plane transmission sub-array is , represents the distance between each plane transmission sub-array and the central plane transmission sub-array, .

4. The spherical conformal transmission array for two-dimensional beam scanning according to claim 2, characterized in that: The crossed-dipole FSS unit is a double-layer cross-shaped metal patch structure, and the patch size, layer spacing and dielectric substrate parameters meet the requirements of linear variation of transmission phase in the 28GHz-32GHz frequency band.

5. The spherical conformal transmission array for two-dimensional beam scanning according to claim 4, characterized in that: The MMSE method is used to compensate the phase mutation at the boundary of adjacent plane transmission subarrays. The quantized phase of the compensated plane transmission subarray is 3-bit. Length of the crossed-dipole FSS unit The transmission phase coverage range is 340° within the length range corresponding to a transmission loss of less than 3dB.

6. The spherical conformal transmission array for two-dimensional beam scanning according to claim 1, characterized in that: The compensation phase of the crossed-dipole FSS unit is: ； In the formula, Indicates Line The first Total phase compensation of row-crossed dipole FSS units; represents the spatial phase delay compensation amount with the cross-dipole FSS unit; Indicates Line The first Line The cross-dipole FSS units in the columns are used to achieve the compensation phase of the corresponding beam pointing; Indicates Line The smoothed phase compensation value of the planar transmission subarray of the column; in, The calculation formula of spatial phase delay compensation is as follows: ； In the formula, Indicates Line The first row of the plane transmission subarray Line Phase compensation amount of the cross-dipole FSS unit in the column; represents the free space wave number; Indicates the center coordinates of the millimeter wave feed antenna With Line The first row of the plane transmission subarray Line The spatial distance of the cross-dipole FSS units of the column; , , Respectively represent the x-, y-, and z-axis coordinates of the center of the millimeter-wave feed antenna; ； In the formula, Indicates Line The elevation angle of the plane transmission subarray beam pointing in the array, and , represents the spatial radius of the central plane transmission subarray, Indicates Line The spatial radius of the plane transmission subarray of the column; Indicates Line The azimuth angle of the plane transmission subarray beam pointing to the array, and , Indicates Line The component of the plane transmission subarray beam of the column in the longitudinal coordinate, Indicates Line The component of the plane transmission subarray beam of the column in the transverse coordinate; Since the spherical conformal transmission array is a two-dimensional symmetrical structure, the remaining plane transmission subarray can be obtained by calculating a quarter of the plane transmission subarray and then rotating it; The smooth phase compensation value of the planar transmission subarray is: ； ； In the formula, Indicates the 3rd row The smoothed phase compensation value of the planar transmission subarray of the column; Indicates the 3rd row The first The cross-dipole FSS unit in the sixth row is to realize the compensation phase of the corresponding beam pointing; Indicates the 3rd row The first The cross-dipole FSS unit in the first column of the row is to realize the compensation phase of the corresponding beam pointing; Indicates The plane transmission subarray of row 3 and column 6 The cross-dipole FSS units in the columns are used to achieve the compensation phase of the corresponding beam pointing; Indicates Line The sixth row of the plane transmission subarray of the column The cross-dipole FSS units in the columns are used to achieve the compensation phase of the corresponding beam pointing; Indicates Line The first Line The cross-dipole FSS units in the columns are used to achieve the compensation phase of the corresponding beam pointing; Indicates Line The first The cross-dipole FSS unit in the first column of the row is to realize the compensation phase of the corresponding beam pointing; Indicates Line The smoothed phase compensation value of the planar transmission subarray of the column; Indicates Line The sixth row of the plane transmission subarray of the column The cross-dipole FSS units in the columns are used to achieve the compensation phase of the corresponding beam pointing; Indicates Line The first row of the plane transmission subarray of the column The cross-dipole FSS units in the columns are used to achieve the compensation phase of the corresponding beam pointing; Indicates Line The smoothed phase compensation value of the planar transmission subarray of the column.

7. The spherical conformal transmission array for two-dimensional beam scanning according to claim 6, characterized in that: The dielectric thickness of the crossed-dipole FSS unit is set to , represents the electrical thickness, and , represents the dielectric constant; h Indicates the dielectric thickness to obtain the maximum transmission phase range.

8. The spherical conformal transmission array for two-dimensional beam scanning according to claim 7, characterized in that: The millimeter wave feed antenna includes multiple microstrip array antennas on the upper layer and a feeding network on the lower layer. A double-thin common ground isolation ring is used between the multiple microstrip array antennas on the upper layer and the feeding network to isolate radiation, avoid antenna short circuit, and suppress mutual coupling effect.

9. The spherical conformal transmission array for two-dimensional beam scanning according to claim 8, characterized in that: Each microstrip array antenna is connected in parallel with a feeding network to ensure radiation stability.

10. The spherical conformal transmission array for two-dimensional beam scanning according to claim 1, characterized in that: The surface of the 3D printed spherical shell carrier is inlaid with 25 planar transmission subarrays, each of which contains 6×6 cross-dipole FSS units.

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