A spherical conformal transmissive array for two-dimensional beam scanning

Abstract

The application discloses a kind of spherical conformal transmission arrays of beam two-dimensional scanning, belong to the field of emergency communication of millimeter wave frequency band, including spherical conformal 3D printing spherical shell carrier, 3D printing spherical shell carrier surface inlaid with multiple plane transmission subarrays according to longitude and latitude distribution, each plane transmission subarray contains periodically arranged cross-dipole FSS unit, and by calculating space phase delay compensation amount, ensure that the radiation phase of each FSS unit of transmission array is superimposed in target direction;Millimeter wave feed antenna is provided below 3D printing spherical shell carrier, different plane transmission subarrays are irradiated by rotating millimeter wave feed, and beam synthesis and control are realized in combination with phase compensation.The spherical conformal transmission array of beam two-dimensional scanning described above 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 scenarios.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of emergency communication in the millimeter wave frequency band, and in particular to a spherical conformal transmissive array for two-dimensional beam scanning. BACKGROUND

[0002] When unexpected events such as natural disasters occur, the communication network at the scene may be damaged or even completely destroyed, thereby causing communication paralysis, personnel disconnection and other problems. In the millimeter wave frequency band, a spherical conformal transmissive array antenna carried by a drone has the characteristics of high gain and large bandwidth, and is widely used, but the traditional transmissive array antenna has the following defects:

[0003] 1. Narrow beam width: the coverage range is limited, and it is difficult to meet the dynamic scene requirements (such as high-speed movement of a drone);

[0004] 2. Large scanning loss: the existing beam scanning method is prone to introducing phase errors when scanning in two dimensions, thereby causing gain to decrease;

[0005] 3. Structural limitation: a planar antenna is difficult to conform to a curved carrier (such as a drone fuselage), thereby affecting the system integration. SUMMARY

[0006] The application aims to provide a spherical conformal transmissive array for two-dimensional beam scanning, and solve the above technical problems.

[0007] To achieve the above-mentioned purpose, the application provides a spherical conformal transmissive array for two-dimensional beam scanning, which comprises a spherical conformal 3D-printed spherical shell carrier, the surface of the 3D-printed spherical shell carrier is inlaid with a plurality of planar transmissive sub-arrays distributed according to longitude and latitude, each planar transmissive sub-array comprises periodically arranged cross-dipole FSS units, and the radiation phase of each FSS unit of the transmissive array is ensured to be superimposed in a target direction by calculating a spatial phase delay compensation amount.

[0008] A millimeter wave feed antenna is arranged below the 3D-printed spherical shell carrier, different planar transmissive sub-arrays are irradiated by rotating the millimeter wave feed antenna, and beam synthesis and control are realized in combination with phase compensation.

[0009] Preferably, it is assumed that a planar transmissive sub-array located at the center of the spherical surface of the 3D-printed spherical shell carrier is a central planar transmissive sub-array, and the coordinates of the remaining planar transmissive sub-arrays are obtained by rotating the central planar transmissive sub-array through a Rodrigues rotation formula, so as to ensure that the distribution of each transmissive sub-array on the spherical surface is uniform and symmetrical.

[0010] The center distance between two adjacent planar transmissive sub-arrays is , represents the working wavelength.

[0011] Preferably, it is assumed that the period length of the planar transmissive sub-array is The coordinate expressions for each cross dipole FSS element in the central plane transmission subarray are as follows:

[0012] ;

[0013] in,

[0014] ;

[0015] In the formula, In the central plane transmission subarray, the first... Line 1 The coordinates of the cross dipole FSS unit in the column; , , They represent the first and second subarrays in the central plane transmission array, respectively. Line 1 The X, Y, and Z coordinates of the cross dipole FSS unit in the column; In the central plane transmission subarray, the first... Line 1 Z-axis coordinates of the cross dipole FSS element in the column;

[0016] The Rodrigues rotation formula rotates the coordinates of each cross dipole FSS element in the central plane transmission subarray around the direction vector. Rotate to obtain the coordinates of the cross dipole FSS elements at corresponding positions on each planar transmission subarray after rotation:

[0017] ;

[0018] in,

[0019] ;

[0020] In the formula, Indicates the first Line 1 The first planar transmission subarray of the column Line 1 The coordinates of the cross dipole FSS unit in the column; , , They represent the first Line 1 The first planar transmission subarray of the column Line 1 The X, Y, and Z coordinates of the cross dipole FSS unit in the column; Indicates the first Line 1 The rotation azimuth angle of the planar transmission subarray of the column; Indicates the first Line 1 The rotation and elevation angles of the plane transmission subarray, and , This represents the distance between each planar transmission subarray and the central planar transmission subarray. .

[0021] Preferably, the cross-dipole FSS unit is a double-layer cross-shaped metal patch structure, and the patch size, interlayer spacing and dielectric substrate parameters meet the requirements for linear change of transmission phase in the 28GHz-32GHz frequency band.

[0022] Preferably, the boundary between adjacent planar transmission subarrays is compensated for phase abrupt changes using the MMSE method, and the quantization phase of the compensated planar transmission subarray is 3-bit.

[0023] Length of cross dipole FSS unit With a length of 2mm-3.41mm, a transmission phase coverage range of 340° is achieved within the length range corresponding to a transmission loss of less than 3dB.

[0024] Preferably, the compensation phase of the cross-dipole FSS unit is:

[0025] ;

[0026] In the formula, Indicates the first Line 1 The first planar transmission subarray in the column Total phase compensation for the cross-dipole FSS unit; This represents the spatial phase delay compensation amount with respect to the cross dipole FSS unit; Indicates the first Line 1 The first planar transmission subarray of the column Line 1 The cross dipole FSS unit of the column is a compensated phase to achieve the corresponding beam pointing; Indicates the first Line 1 The smooth phase compensation value of the planar transmission subarray of the column;

[0027] in,

[0028] The formula for calculating the spatial phase delay compensation is as follows:

[0029] ;

[0030] In the formula, Indicates the first Line 1 The first planar transmission subarray of the column Line 1 Phase compensation amount of the cross dipole FSS unit in the column; Represents the free space wavenumber; Represents the center coordinates of the millimeter-wave feed antenna With the Line 1 The first planar transmission subarray of the column Line 1 Spatial distance of cross dipole FSS units in a column; , , These represent the x, y, and z axis coordinates of the center of the millimeter-wave feed antenna, respectively.

[0031] ;

[0032] In the formula, Indicates the first Line 1 The elevation angle of the beam pointing to the planar transmission subarray of the column, and , This represents the spatial radius of the central plane transmission subarray. Indicates the first Line 1 The spatial radius of the planar transmission subarray of the column; Indicates the first Line 1 The azimuth angle of the beam pointing to the planar transmission subarray of the column, and , Indicates the first Line 1 The components of the planar transmission subarray beams in the longitudinal coordinate system. Indicates the first Line 1 The components of the planar transmission subarray beam on the horizontal coordinate;

[0033] Since the spherical conformal transmission array is a two-dimensional symmetric structure, the remaining planar transmission subarray can be obtained by calculating the quarter-plane transmission subarray and then rotating it.

[0034] The smooth phase compensation value of the planar transmission subarray is:

[0035] ;

[0036] ;

[0037] In the formula, Indicates the 3rd line, The smooth phase compensation value of the planar transmission subarray of the column; Indicates the 3rd line, The first planar transmission subarray of the column The cross-dipole FSS elements in row 6, column 6 of the planar transmissive subarray are at a compensating phase to achieve a corresponding beam pointing; represents a smooth phase compensation value for the planar transmissive subarray in row 3, column 3. represents a compensating phase for the cross-dipole FSS elements in row 6, column 1 of the planar transmissive subarray to achieve a corresponding beam pointing; represents a compensating phase for the cross-dipole FSS elements in row 6, column 1 of the planar transmissive subarray to achieve a corresponding beam pointing; represents a smooth phase compensation value for the planar transmissive subarray in row 3, column 3. represents a compensating phase for the cross-dipole FSS elements in row 6, column 1 of the planar transmissive subarray to achieve a corresponding beam pointing; represents a compensating phase for the cross-dipole FSS elements in row 6, column 1 of the planar transmissive subarray to achieve a corresponding beam pointing; represents a smooth phase compensation value for the planar transmissive subarray in row 3, column 3. represents a compensating phase for the cross-dipole FSS elements in row 6, column 1 of the planar transmissive subarray to achieve a corresponding beam pointing; represents a compensating phase for the cross-dipole FSS elements in row 6, column 1 of the planar transmissive subarray to achieve a corresponding beam pointing; represents a compensating phase for the cross-dipole FSS elements in row 6, column 1 of the planar transmissive subarray to achieve a corresponding beam pointing; represents a smooth phase compensation value for the planar transmissive subarray in row 3, column 3. represents a compensating phase for the cross-dipole FSS elements in row 6, column 1 of the planar transmissive subarray to achieve a corresponding beam pointing; represents a compensating phase for the cross-dipole FSS elements in row 6, column 1 of the planar transmissive subarray to achieve a corresponding beam pointing; represents a compensating phase for the cross-dipole FSS elements in row 6, column 1 of the planar transmissive subarray to achieve a corresponding beam pointing; represents a smooth phase compensation value for the planar transmissive subarray in row 3, column 3. represents a compensating phase for the cross-dipole FSS elements in row 6, column 1 of the planar transmissive subarray to achieve a corresponding beam pointing; represents a compensating phase for the cross-dipole FSS elements in row 6, column 1 of the planar transmissive subarray to achieve a corresponding beam pointing; represents a compensating phase for the cross-dipole FSS elements in row 6, column 1 of the planar transmissive subarray to achieve a corresponding beam pointing; represents a compensating phase for the cross-dipole FSS elements in row 6, column 1 of the planar transmissive subarray to achieve a corresponding beam pointing; represents a smooth phase compensation value for the planar transmissive subarray in row 3, column 3. represents a compensating phase for the cross-dipole FSS elements in row 6, column 1 of the planar transmissive subarray to achieve a corresponding beam pointing; represents a compensating phase for the cross-dipole FSS elements in row 6, column 1 of the planar transmissive subarray to achieve a corresponding beam pointing; represents a compensating phase for the cross-dipole FSS elements in row 6, column 1 of the planar transmissive subarray to achieve a corresponding beam pointing; represents a smooth phase compensation value for the planar transmissive subarray in row 3, column 3. represents a compensating phase for the cross-dipole FSS elements in row 6, column 1 of the planar transmissive subarray to achieve a corresponding beam pointing; represents a compensating phase for the cross-dipole FSS elements in row 6, column 1 of the planar transmissive subarray to achieve a corresponding beam pointing; represents a compensating phase for the cross-dipole FSS elements in row 6, column 1 of the planar transmissive subarray to achieve a corresponding beam pointing; represents a smooth phase compensation value for the planar transmissive subarray in row 3, column 3. represents a compensating phase for the cross-dipole FSS elements in row 6, column 1 of the planar transmissive subarray to achieve a corresponding beam pointing; represents a compensating phase for the cross-dipole FSS elements in row 6, column 1 of the planar transmissive subarray to achieve a corresponding beam pointing; represents a compensating phase for the cross-dipole FSS elements in row 6, column 1 of the planar transmissive subarray to achieve a corresponding beam pointing; represents a smooth phase compensation value for the planar transmissive subarray in row 3, column 3. represents a compensating phase for the cross-dipole FSS elements in row 6, column 1 of the planar transmissive subarray to achieve a corresponding beam pointing;

[0038] Preferably, the dielectric thickness of the cross-dipole FSS elements is set to , represents the electrical thickness, and , represents the dielectric constant. This indicates the thickness of the medium to obtain the maximum transmission phase range.

[0039] Preferably, the millimeter-wave feed antenna includes multiple microstrip array antennas in the upper layer and a feed network in the lower layer. The multiple microstrip array antennas in the upper layer and the feed network are isolated by a double thin-layer common ground isolation ring to isolate radiation, avoid antenna short circuits, and suppress mutual coupling effects.

[0040] Preferably, each microstrip array antenna is connected in parallel with the feed network to ensure radiation stability.

[0041] Preferably, the surface of the 3D printed spherical carrier is inlaid with 25 planar transmission subarrays, each planar transmission subarray containing 6×6 cross dipole FSS units.

[0042] Therefore, the present invention employs the above-mentioned two-dimensional beam scanning spherical conformal transmission array, which has the following beneficial effects:

[0043] 1. Improved Coverage: By continuously rotating the feed to illuminate the corresponding transmission subarray, this scheme achieves two-dimensional beam scanning. This significantly improves the antenna's coverage, enabling effective communication connections to be maintained even in complex terrain or disaster-stricken areas.

[0044] 2. More flexible and accurate beam scanning: By using at least 4 sub-beams to synthesize a main beam with a desired direction, two-dimensional continuous beam control can be achieved by adjusting the direction of the sub-beams;

[0045] 3. The FSS unit used is a cross-dipole patch, which has a stable transmission coefficient. Even when the incident angle increases to 45°, the maximum transmission loss is only 2dB, ensuring the overall performance of the transmission array is stable and reliable.

[0046] 4. Different resonant frequencies can be excited by changing the size of the FSS unit to obtain the required transmission phase, so that the transmission phase coverage range within the length range corresponding to a transmission loss of less than 3dB is about 340°, which meets the 3-bit quantization phase requirement.

[0047] 5. Directional beamforming and lightweight design: Utilizing... The microstrip array antenna is used as a feed source to obtain a directional beam similar to a horn, while minimizing weight, which is beneficial for the mounting and endurance of carriers such as drones; at the same time, a double thin-layer common ground isolation ring is used to isolate the radiating element and the feed network, avoiding mutual coupling between the antenna and the feed network from degrading the radiation pattern, and ensuring the stable radiation performance of the feed antenna.

[0048] 6. Phase compensation mechanism: By accurately calculating the phase compensation value of each FSS element, the expected beam pointing is achieved, ensuring the beam scanning accuracy and coverage of the antenna system;

[0049] 7. Subarray edge phase smoothing processing: the subarray edge phase smoothing processing technology is adopted, the phase mutation between the subarrays is reduced, the shape of the directional diagram is improved, the main lobe is more sharp, and the sidelobe is greatly reduced.

[0050] The technical solutions of the application are described in further detail below with reference to the drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0051] Figure 1 A simulation structure diagram of a spherical conformal transmissive array for beam two-dimensional scanning described in the simulation experiment of the application;

[0052] Figure 2 A beam control principle diagram described in the simulation experiment of the application;

[0053] Figure 3 Geometric diagrams of a planar transmissive subarray described in the simulation experiment of the application, wherein (a) is a planar transmissive subarray distribution diagram; (b) is a planar transmissive subarray internal composition schematic diagram; (c) is a planar transmissive subarray three-dimensional structure schematic diagram; and (d) is a planar transmissive subarray rotation and position parameter schematic diagram;

[0054] Figure 4 A structure schematic diagram of a cross-dipole FSS unit described in the simulation experiment of the application, wherein (a) is a top view of the cross-dipole FSS unit; and (b) is a cross-sectional view of the cross-dipole FSS unit;

[0055] Figure 5 Simulation results of the cross-dipole FSS unit described in the simulation experiment of the application, wherein (a) is a curve diagram of the transmittance coefficient of the cross-dipole FSS unit changing with frequency; and (b) is a curve diagram of the transmittance coefficient of the cross-dipole FSS unit changing with length ;

[0056] Figure 6 Simulation result diagrams of the cross-dipole FSS unit when a microstrip array antenna is used as an illumination feed source in the simulation experiment of the application, wherein (a) is a microstrip array antenna arrangement diagram; (b) is a feed line structure design diagram; and (c) is a microstrip array antenna cross-sectional view;

[0057] Figure 7 A beam pointing schematic diagram described in the simulation experiment of the application, wherein (a) is a 25-transmissive subarray beam pointing distribution diagram, and (b) is a beam pointing angle derivation principle diagram in a Cartesian coordinate system;

[0058] Figure 8 A phase smoothing setting directional diagram comparison diagram;

[0059] Figure 9The phase distribution diagram of the planar unfolding structure of the spherical conformal transmissive array described in the simulation experiment of the application, wherein (a) is a pre-smoothing phase distribution diagram, and (b) is a post-smoothing phase distribution diagram;

[0060] Figure 10 The simulation directional diagram of the spherical conformal transmissive array described in the simulation experiment of the application under different ;

[0061] Figure 11 The two-dimensional beam scanning schematic diagram of the spherical conformal transmissive array described in the simulation experiment of the application, wherein (a) is a curve diagram of the gain change with the observation angle or when the polarization angle , and (b) is a curve diagram of the gain change with the observation angle or when the polarization angle . DETAILED DESCRIPTION

[0062] In order to make the purpose, technical solutions and advantages of the embodiments of the application clearer, the embodiments of the application are further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the embodiments of the application and not to limit the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of the application. Examples of the described embodiments are shown in the drawings, wherein the same or similar reference numbers represent the same or similar elements or elements having the same or similar functions throughout.

[0063] It should be noted that the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or server comprising a series of steps or units does not have to be limited to only those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to the process, method, product or device.

[0064] The embodiments of the application are described in detail below with reference to the drawings.

[0065] A spherical conformal transmissive array for two-dimensional beam scanning includes a spherical conformal 3D printed spherical shell carrier, and the surface of the 3D printed spherical shell carrier is embedded with a plurality of planar transmissive sub-arrays distributed in a latitude-longitude manner, each planar transmissive sub-array includes periodically arranged cross-dipole FSS units, and the radiation phase of each FSS unit (frequency selective surface unit) of the transmissive array is ensured to be superimposed in a target direction by calculating a spatial phase delay compensation amount;

[0066] Specifically,

[0067] The compensation phase of the cross-dipole FSS unit is:

[0068] ;

[0069] In the formula, represents the total phase compensation of the cross-dipole FSS unit in the plane transmission subarray in the i-th row and the j-th column; represents the phase compensation of the cross-dipole FSS unit in the i-th row and the j-th column of the plane transmission subarray in the i-th row and the j-th column; represents the phase compensation of the cross-dipole FSS unit in the i-th row and the j-th column of the plane transmission subarray in the i-th row and the j-th column; represents the total phase compensation of the cross-dipole FSS unit in the i-th row and the j-th column of the plane transmission subarray in the i-th row and the j-th column; represents the spatial phase delay compensation amount of the cross-dipole FSS unit; represents the phase compensation amount of the cross-dipole FSS unit in the i-th row and the j-th column of the plane transmission subarray in the i-th row and the j-th column; represents the phase compensation amount of the cross-dipole FSS unit in the i-th row and the j-th column of the plane transmission subarray in the i-th row and the j-th column; represents the phase compensation amount of the cross-dipole FSS unit in the i-th row and the j-th column of the plane transmission subarray in the i-th row and the j-th column; represents the phase compensation amount of the cross-dipole FSS unit in the i-th row and the j-th column of the plane transmission subarray in the i-th row and the j-th column; represents the phase compensation amount of the cross-dipole FSS unit in the i-th row and the j-th column of the plane transmission subarray in the i-th row and the j-th column; represents the smooth phase compensation value of the plane transmission subarray in the i-th row and the j-th column; represents the smooth phase compensation value of the plane transmission subarray in the i-th row and the j-th column; represents the smooth phase compensation value of the plane transmission subarray in the i-th row and the j-th column;

[0070] wherein,

[0071] The spatial phase delay compensation amount is calculated as follows:

[0072] ;

[0073] In the formula, represents the phase compensation amount of the cross-dipole FSS unit in the i-th row and the j-th column of the plane transmission subarray in the i-th row and the j-th column; represents the phase compensation amount of the cross-dipole FSS unit in the i-th row and the j-th column of the plane transmission subarray in the i-th row and the j-th column; represents the phase compensation amount of the cross-dipole FSS unit in the i-th row and the j-th column of the plane transmission subarray in the i-th row and the j-th column; represents the phase compensation amount of the cross-dipole FSS unit in the i-th row and the j-th column of the plane transmission subarray in the i-th row and the j-th column; represents the phase compensation amount of the cross-dipole FSS unit in the i-th row and the j-th column of the plane transmission subarray in the i-th row and the j-th column; represents the free space wave number; represents the x, y, z axis coordinates of the center of the millimeter wave feed antenna; represents the spatial distance of the cross-dipole FSS unit in the i-th row and the j-th column of the plane transmission subarray in the i-th row and the j-th column; represents the spatial distance of the cross-dipole FSS unit in the i-th row and the j-th column of the plane transmission subarray in the i-th row and the j-th column; represents the spatial distance of the cross-dipole FSS unit in the i-th row and the j-th column of the plane transmission subarray in the i-th row and the j-th column; represents the x, y, z axis coordinates of the center of the millimeter wave feed antenna; represents the x, y, z axis coordinates of the center of the millimeter wave feed antenna;

[0074] ;

[0075] In the formula, represents the elevation angle of the beam pointing of the plane transmission subarray in the i-th row and the j-th column, and , ​​​​​denotes the spatial radius of the central planar transmitting subarray, denotes the spatial radius of the planar transmitting subarray in the 3rd row and 3rd column, denotes the spatial radius of the planar transmitting subarray in the 3rd row and 3rd column, denotes the spatial radius of the planar transmitting subarray in the 3rd row and 3rd column, and , , , and denote the rotation elevation angle of the planar transmitting subarray in the 3rd row and 3rd column, 3rd row and 3rd column, respectively; denote the rotation elevation angle of the planar transmitting subarray in the 3rd row and 3rd column, 3rd row and 3rd column, respectively; denote the rotation elevation angle of the planar transmitting subarray in the 3rd row and 3rd column, 3rd row and 3rd column, respectively; denotes the azimuth angle of the planar transmitting subarray beam pointing in the 3rd row and 3rd column, denotes the azimuth angle of the planar transmitting subarray beam pointing in the 3rd row and 3rd column, denotes the azimuth angle of the planar transmitting subarray beam pointing in the 3rd row and 3rd column, denotes the azimuth angle of the planar transmitting subarray beam pointing in the 3rd row and 3rd column, denotes the azimuth angle of the planar transmitting subarray beam pointing in the 3rd row and 3rd column, denotes the azimuth angle of the planar transmitting subarray beam pointing in the 3rd row and 3rd column, denotes the azimuth angle of the planar transmitting subarray beam pointing in the 3rd row and 3rd column, denotes the azimuth angle of the planar transmitting subarray beam pointing in the 3rd row and 3rd column, denotes the azimuth angle of the planar transmitting subarray beam pointing in the 3rd row and 3rd column, denotes the azimuth angle of the planar transmitting subarray beam pointing in the 3rd row and 3rd column,

[0076] Since the spherical conformal transmitting array is a two-dimensional symmetric structure, the remaining planar transmitting subarrays can be obtained by calculating a quarter planar transmitting subarray (such as the quarter subarray region selected by a box) and then rotating it; Figure 7

[0077] The smooth phase compensation value of the planar transmitting subarray is:

[0078] ;

[0079] ;

[0080] In the formula, denotes the smooth phase compensation value of the planar transmitting subarray in the 3rd row and 3rd column; denotes the compensation phase realized by the cross-dipole FSS unit in the 3rd row and 6th column of the planar transmitting subarray in the 3rd row and 3rd column; denotes the compensation phase realized by the cross-dipole FSS unit in the 3rd row and 1st column of the planar transmitting subarray in the 3rd row and 3rd column; denotes the compensation phase realized by the cross-dipole FSS unit in the 6th row and 3rd column of the planar transmitting subarray in the 3rd row and 3rd column; denotes the compensation phase realized by the cross-dipole FSS unit in the 6th row and 3rd column of the planar transmitting subarray in the 3rd row and 3rd column; denotes the compensation phase realized by the cross-dipole FSS unit in the 6th row and 3rd column of the planar transmitting subarray in the 3rd row and 3rd column; denotes the compensation phase realized by the cross-dipole FSS unit in the 6th row and 3rd column of the planar transmitting subarray in the 3rd row and 3rd column; denotes the compensation phase realized by the cross-dipole FSS unit in the 6th row and 3rd column of the planar transmitting subarray in the 3rd row and 3rd column; denotes the compensation phase realized by the cross-dipole FSS unit in the 6th row and 3rd column of the planar transmitting subarray in the 3rd row and 3rd column; denotes the compensation phase realized by the cross-dipole FSS unit in the 6th row and 3rd column of the planar transmitting subarray in the 3rd row and 3rd column; denotes the compensation phase realized by the cross-dipole FSS unit in the 6th row and 3rd column of the planar transmitting subarray in the 3rd row and 3rd column; denotes the compensation phase realized by the cross-dipole FSS unit in the 6th row and 3rd column of the planar transmitting subarray in the 3rd row and 3rd column; denotes the compensation phase realized by the cross-dipole FSS unit in the 6th row and 3rd column of the planar transmitting subarray in the 3rd row and 3rd column; ​Row 6, Column 6 of the planar transmissive subarray Row 6, Column 6 of the cross-dipole FSS unit on the planar transmissive subarray for compensating phase for corresponding beam pointing; Row 6, Column 6 of the planar transmissive subarray Row 6, Column 6 of the planar transmissive subarray Row 6, Column 6 of the cross-dipole FSS unit on the planar transmissive subarray for compensating phase for corresponding beam pointing; Row 6, Column 6 of the planar transmissive subarray Row 6, Column 6 of the cross-dipole FSS unit on the planar transmissive subarray for compensating phase for corresponding beam pointing; Row 6, Column 6 of the planar transmissive subarray Row 6, Column 6 of the planar transmissive subarray Row 6, Column 6 of the cross-dipole FSS unit on the planar transmissive subarray for compensating phase for corresponding beam pointing; Row 6, Column 6 of the planar transmissive subarray Row 6, Column 6 of the planar transmissive subarray Row 6, Column 6 of the planar transmissive subarray Row 6, Column 6 of the cross-dipole FSS unit on the planar transmissive subarray for compensating phase for corresponding beam pointing; Row 6, Column 6 of the planar transmissive subarray Row 6, Column 6 of the planar transmissive subarray Row 6, Column 6 of the cross-dipole FSS unit on the planar transmissive subarray for compensating phase for corresponding beam pointing; Row 6, Column 6 of the planar transmissive subarray Row 6, Column 6 of the planar transmissive subarray Row 6, Column 6 of the planar transmissive subarray Row 6, Column 6 of the cross-dipole FSS unit on the planar transmissive subarray for compensating phase for corresponding beam pointing; Row 6, Column 6 of the planar transmissive subarray Row 6, Column 6 of the planar transmissive subarray Row 6, Column 6 of the planar transmissive subarray Row 6, Column 6 of the planar transmissive subarray

[0081] In the present embodiment, the phase smoothing derivation process for the edges of two adjacent planar transmissive subarrays is as follows:

[0082] Suppose , , the expected beam synthesis direction , at this time the phase difference , at this time the array factors of the two subarrays are respectively:

[0083] ;

[0084] ;

[0085] Using Euler's formula, the amplitudes of the two subarrays in the direction are respectively:

[0086] ;

[0087] Thus, we can obtain Total amplitude in direction for:

[0088] ;

[0089] After simplification, we get: .

[0090] Therefore, it can be known that the phase abrupt change value at the edge of the subarray is... The larger the mutation 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.

[0091] For a transmission array antenna, although the initial radiation is from the feed source, according to Huygens' principle, the illuminated FSS element, as a secondary wave source, can also be considered as radiating itself. Therefore, the above derivation regarding the edge phase change still applies to transmission array antennas.

[0092] A millimeter-wave feed antenna is installed below the 3D-printed spherical carrier. By rotating the millimeter-wave feed to illuminate different planar transmission subarrays, beamforming and control are achieved in combination with phase compensation.

[0093] Assuming the planar transmission subarray located at the center of the spherical surface of the 3D printed spherical carrier is the central planar transmission subarray, the coordinates of the remaining planar 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.

[0094] Center-to-center distance between two adjacent planar transmission subarrays , Indicates the operating wavelength.

[0095] At this point, assume the period length of the planar transmission subarray is... The coordinate expressions for each cross dipole FSS element in the central plane transmission subarray are as follows:

[0096] ;

[0097] in,

[0098] ;

[0099] In the formula, In the central plane transmission subarray, the first... Line 1 The coordinates of the cross dipole FSS unit in the column; , , They represent the first and second subarrays in the central plane transmission array, respectively. Line 1 The X, Y, and Z coordinates of the cross dipole FSS unit in the column; In the central plane transmission subarray, the first... Line 1 Z-axis coordinates of the cross dipole FSS element in the column;

[0100] The Rodrigues rotation formula rotates the coordinates of each cross dipole FSS element in the central plane transmission subarray around the direction vector. Rotate to obtain the coordinates of the cross dipole FSS elements at corresponding positions on each planar transmission subarray after rotation:

[0101] ;

[0102] Will as well as ( Indicates the first Line 1 The rotation axis direction vector of the planar transmission subarray of the column, and , , , and They represent the first Line 1 The projected coordinates of the center of the planar transmission subarray in the xoy plane; (This represents the wavenumber;) Substituting into the above formula, we obtain the coordinates of the cross dipole FSS elements at corresponding positions on each planar transmission subarray after rotation:

[0103] ;

[0104] in,

[0105] ;

[0106] In the formula, Indicates the first Line 1 The first planar transmission subarray of the column Line 1 The coordinates of the cross dipole FSS unit in the column; , , They represent the first Line 1 The first planar transmission subarray of the column Line 1 The X, Y, and Z coordinates of the cross dipole FSS unit in the column; Indicates the first Line 1 The rotation azimuth angle of the planar transmission subarray of the column; Indicates the first Line number The rotation and elevation angles of the plane transmission subarray, and , This represents the distance between each planar transmission subarray and the central planar transmission subarray. .

[0107] The cross-dipole FSS unit is a double-layer cross-shaped metal patch structure, and the patch size, interlayer spacing and dielectric substrate parameters meet the requirements for linear change of transmission phase in the 28GHz-32GHz frequency band.

[0108] Furthermore, the boundary between adjacent planar transmission subarrays is compensated for phase abrupt changes using the MMSE method, resulting in a 3-bit quantization phase for the compensated planar transmission subarray; the length of the cross dipole FSS unit... With a length of 2mm-3.41mm, a transmission phase coverage range of 340° is achieved within the length range corresponding to a transmission loss of less than 3dB.

[0109] The dielectric thickness of the cross-dipole FSS unit is set to , Indicates electrical thickness, and , Indicates the dielectric constant; This indicates the thickness of the medium to obtain the maximum transmission phase range.

[0110] The millimeter-wave feed antenna consists of multiple microstrip array antennas in the upper layer and a feed network in the lower layer. The upper-layer microstrip array antennas and the feed network are isolated by a double-thin-layer common-ground isolation ring to prevent short circuits and suppress mutual coupling effects. Furthermore, each microstrip array antenna is connected in parallel with the feed network to ensure radiation stability.

[0111] The surface of the 3D printed spherical carrier is inlaid with 25 planar transmission subarrays, each containing 6×6 cross dipole FSS units.

[0112] Simulation Experiment

[0113] For example Figure 1 The spherical conformal transmission array for two-dimensional beam scanning shown is based on, for example, Figure 2 The beam control principle shown is used as an example for explanation. Figure 2 In the diagram (where a33 is the central plane transmission subarray), it can be seen that in one-dimensional beamforming, two sub-beams can be combined to form a new beam, and the direction of the combined beam will change accordingly by adjusting the directions of the two sub-beams. However, in two-dimensional beamforming, to achieve continuous two-dimensional beam control, at least four sub-beams must be used to combine a main beam with a desired direction, and the direction of the combined beam is approximately equal to the elevation angle of each sub-beam. and azimuth The weighted mean:

[0114] ;

[0115] In the formula, They represent the first The pitch angle of a sub-beam; Indicates the first The azimuth angle of each sub-beam.

[0116] Based on the above principles, it is known that by continuously rotating the feed source to illuminate the corresponding transmission subarrays, sub-beams with different directions can be generated, thereby synthesizing the desired highly directional beam. Furthermore, to achieve two-dimensional and continuous beam scanning, the four transmission subarrays should be adjacent to each other. Therefore, this invention adopts a spherical conformal transmission array topology, and employs... Figure 4 The cross-dipole FSS unit structure shown has the following dimensional parameters: period Width , length dielectric constant .

[0117] Simulation results of the cross-dipole FSS unit based on the above structure are as follows: Figure 5 As shown, the cross-dipole FSS unit maintains a highly stable transmission phase even when facing incident beams at different angles. While the transmission amplitude attenuates slightly at certain frequencies with increasing incident angle, the maximum transmission loss is only 2dB even at 45°, which is crucial for ensuring the overall performance of the transmission array. Furthermore, the cross-dipole FSS unit exhibits different transmission phases at different frequencies; therefore, different resonant frequencies can be excited by changing the size of the cross-dipole FSS unit, thereby obtaining the desired transmission phase.

[0118] like Figure 6 As shown, when a microstrip array antenna is selected as the illumination feed structure, when... At that time, the transmission loss is less than 1.5 dB. Subsequently, transmission loss increases dramatically. When At this time, the change in transmission phase is relatively flat. Therefore, considering both transmission loss and transmission phase, a compromise is made. The value is set between 2mm and 3.41mm. At this time, the transmission phase coverage range within the length range corresponding to a transmission loss of less than 3dB is about 340°, which meets the requirements of a complete 3-bit quantization phase (3-bit quantization phase requires a phase coverage range of 315°).

[0119] To achieve a horn-like directional beam while reducing weight, the following method is employed: Figure 6 shown The microstrip array antenna is used as a feed source. Meanwhile, considering the microstrip array antenna as a feed source in the transmission array, a well-symmetrical directional diagram is very important. Therefore, a double-thin-layer common-ground isolation ring is used to isolate the microstrip array antenna and the feed network.

[0120] Based on the above structure, a phase compensation simulation experiment is performed as shown in Figure 7 The beam pointing direction of the center plane transmission subarray a33 is set to the+zaxis , . A certain pitch angle gradient is set in the xy two main coordinate axes , . Meanwhile, considering the beam coverage range and gain of the plane transmission subarray, the pitch value of the two main planes is set to 10°. At this time, the beam pointing direction of other subarrays can be derived according to the existing beam angles of the two axes:

[0121] ;

[0122] In the formula, , a3,1 represents the beam pointing direction of the plane transmission subarray in the first row and the first column; , a3,3 represents the beam pointing direction of the plane transmission subarray in the third row and the third column; , a3,2 represents the beam pointing direction of the plane transmission subarray in the third row and the second column; , a3,4 represents the beam pointing direction of the plane transmission subarray in the third row and the fourth column; , and a3 represents the beam pointing direction of the center plane transmission subarray

[0123] Figure 7 In the (b) diagram in , , , , and respectively represent the pointing directions of different sub-beams, and are the lengths of the projections of the vectors

[0124] ;

[0125] Thus, the compensation phase for different beam pointing directions can be easily obtained.

[0126] As shown in Figure 8As shown, the abrupt phase changes at the edges of the planar transmission subarrays severely degrade the radiation pattern. Therefore, to obtain a good radiation pattern, phase smoothing processing of the planar transmission subarray boundaries is necessary. Since the phase of each planar transmission subarray is a relative value, as long as the phase between each FSS element within it remains unchanged, the beam pointing will not be affected. Therefore, a smooth phase transition between the edges of the planar transmission subarrays can be achieved by adding or subtracting a certain value. Thus, the central planar transmission subarray a33 is used as the initial reference subarray, and then the outer planar transmission subarrays are sequentially recursively applied. First, a phase constant is compensated for each planar transmission subarray. ,and , This indicates that the central plane transmission subarray a33 is a compensated phase to achieve the corresponding beam pointing. This represents the phase constant.

[0127] Combination Figure 3 It can be seen that the planar transmission subarrays a23 and a32 are adjacent to the central planar transmission subarray a33, therefore their calculation methods are basically the same. Taking a32 as an example, it contains... In the FSS unit, column 6 of a32 is adjacent to column 1 of a33 (and row 6 of a23 is adjacent to a33). The MMSE method is used to traverse the boundary smoothing phase values ​​of a32. ,get:

[0128] ;

[0129] In the formula, In a32, the first... The direction phase value of the FSS cell in row 6; Indicates the first term in a33 The direction phase value of the FSS cell in the first row and first column;

[0130] Use again This allows for a smooth transition in the phase of the planar transmission subarray.

[0131] For the smoothed phase of a bilateral 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. :

[0132]

[0133] In the formula, In a22, the first... The direction phase value of the FSS cell in row 6; In a23, the first... The direction phase value of the FSS cell in the first row and first column; This refers to the 6th line of a22. The direction phase value of the FSS cell in the column; This indicates the first line of a22. The direction phase value of the FSS cell in the column; This represents the boundary smoothing phase value of a23;

[0134] Similarly, the phase smoothing values ​​for all planar transmission subarrays can be solved, and the transmission array pattern after smoothing is shown below. Figure 8 As shown by the solid line, the main lobe of the beam is sharper and the side lobes are significantly reduced.

[0135] Considering design complexity and antenna performance, a 3-bit quantization phase was used (i.e., taking one phase every 45°, for a total of 8 states). For a planar unfolded planar transmission subarray, the phase distribution before and after smoothing is as follows: Figure 9 As shown, the unprocessed phase distribution is chaotic and irregular, especially for the phase numbered... ( The planar transmission subarray, compared to the phase distribution before smoothing, has a smoother phase transition after processing.

[0136] like Figure 10 As shown, for a spherical conformal transmission array, the projected spacing between antennas... Determines the rotation angle of the planar transmission subarray This determines the antenna's radiation performance, and the simulation results are as follows: Figure 11 As shown, to ensure that the planar transmission subarrays on the sphere do not overlap, The minimum value must be 2.52. (Each planar transmission subarray has a side length of 2.4) At this point, the spherical conformal transmission array has the most compact structure and a gain of 20.9 dBi. However, the spacing between the planar transmission subarrays is too small, making physical fabrication impossible. When the spacing between the planar transmission subarrays increases to... = 3 At this time, sufficient space can be filled with 3D printed material to serve as the overall support structure. However, larger gaps will lead to a decrease in pattern gain and an increase in sidelobe level (because the gap area cannot adjust the beam phase, thus increasing the sidelobes of the synthesized pattern). In addition, when the feed beam illumination area is fixed, increasing the area of ​​the gap will reduce the effective aperture of the synthesized expected beam, thereby reducing the gain of the main lobe of the pattern. Therefore, in order to balance antenna performance and physical fabrication, the subarray spacing is adjusted to... = 2.7 At this time, the antenna gain is about 20.2 dBi, the pattern shape is good, the scanning loss is small, and a good effect is achieved, thereby proving the effectiveness of the application.

[0137] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, but not to limit them. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can still be modified or equivalently replaced, and these modifications or equivalent replacements should not make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A spherical conformal transmission array for two-dimensional beam scanning, characterized in that: It includes a 3D-printed spherical shell carrier with a spherical conformal surface. The surface of the 3D-printed spherical shell carrier is inlaid with multiple planar transmission subarrays distributed in latitude and longitude. Each planar transmission subarray contains periodically arranged cross dipole FSS units. By calculating the spatial phase delay compensation, 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 installed below the 3D-printed spherical carrier. By rotating the millimeter-wave feed to illuminate different planar transmission subarrays, beamforming 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 the planar transmission subarray located at the center of the spherical surface of the 3D printed spherical carrier is the central planar transmission subarray, the coordinates of the remaining planar 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. Center-to-center distance between two adjacent planar transmission subarrays , Indicates the operating wavelength.

3. The spherical conformal transmission array for two-dimensional beam scanning according to claim 2, characterized in that: Assume the period length of the planar transmission subarray is The coordinate expressions for each cross dipole FSS element in the central plane transmission subarray are as follows: ； in, ； In the formula, In the central plane transmission subarray, the first... Line number The coordinates of the cross dipole FSS unit in the column; , , They represent the first and second subarrays in the central plane transmission array, respectively. Line number The X, Y, and Z coordinates of the cross dipole FSS unit in the column; In the central plane transmission subarray, the first... Line number Z-axis coordinates of the cross dipole FSS element in the column; The Rodrigues rotation formula rotates the coordinates of each cross dipole FSS element in the central plane transmission subarray around the direction vector. Rotate to obtain the coordinates of the cross dipole FSS elements at corresponding positions on each planar transmission subarray after rotation: ； in, ； In the formula, Indicates the first Line number The first planar transmission subarray of the column Line number The coordinates of the cross dipole FSS unit in the column; , , They represent the first Line number The first planar transmission subarray of the column Line number The X, Y, and Z coordinates of the cross dipole FSS unit in the column; Indicates the first Line number The rotation azimuth angle of the planar transmission subarray of the column; Indicates the first Line number The rotation and elevation angles of the plane transmission subarray, and , This represents the distance between each planar transmission subarray and the central planar transmission subarray. .

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

5. A spherical conformal transmission array for two-dimensional beam scanning according to claim 4, characterized in that: The boundary between adjacent planar transmission subarrays is compensated for phase abrupt changes using the MMSE method; Length of cross dipole FSS unit With a length of 2mm-3.41mm, a transmission phase coverage range of 340° is achieved within the length range corresponding to a transmission loss of less than 3dB.

6. A spherical conformal transmission array for two-dimensional beam scanning according to claim 5, characterized in that: The dielectric thickness of the cross-dipole FSS unit is set to , Indicates electrical thickness, and , Indicates the dielectric constant; This indicates the thickness of the medium to obtain the maximum transmission phase range.

7. A spherical conformal transmission array for two-dimensional beam scanning according to claim 6, characterized in that: The millimeter-wave feed antenna consists of multiple microstrip array antennas in the upper layer and a feed network in the lower layer. The multiple microstrip array antennas in the upper layer and the feed network are isolated from each other by a double thin-layer common ground isolation ring to avoid antenna short circuits and suppress mutual coupling effects.

8. A spherical conformal transmission array for two-dimensional beam scanning according to claim 7, characterized in that: Each microstrip array antenna is connected in parallel with the feed network to ensure radiation stability.

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

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