Antenna array for conformality of special-shaped surface of aircraft and layout method of antenna array

Abstract

The invention discloses a conformal antenna array layout method for a special-shaped surface of an aircraft, and the method comprises the steps: firstly giving an array element initial parameter of a planar antenna array, converting the special-shaped surface of the aircraft into a two-dimensional curved surface, obtaining a conformal curved surface array factor according to a mapping relation, determining the positions x'n, y'n and z'n of a curved surface antenna array element, the maximum main curvature radius direction and the maximum main curvature radius k1i of the normal vector, and the minimum main curvature radius direction and the minimum main curvature radius k2i of the normal vector; performing curved surface conformal simulation on a single planar antenna according to the positions x'n, y'n and z'n of the array elements of the curved surface antenna, placing an antenna unit by taking a normal vector as a normal vector, performing conformal simulation along the direction of the minimum main curvature radius, and setting the cylindrical surface radius as k2n, and then simulating to obtain a single antenna far-field radiation pattern, synthesizing all antenna far-field radiation patterns according to the positions of the curved surface antenna array elements to obtain a total field pattern function, judging whether the antenna radiation characteristics meet design indexes, and if not, returning to continue to optimize the planar antenna array factors until the design indexes are met.

Description

Technical Field

[0001] The present invention belongs to the technical field of aircraft antennas, and in particular to an antenna array for conforming to an aircraft's irregularly shaped surface and a layout method thereof. Background Art

[0002] In radio systems, antennas are responsible for transmitting and receiving radio signals and are essential front-end components of electronic equipment. Antenna performance is closely linked to the overall system's capabilities. Traditional antennas, whether mounted internally or externally, affect aerodynamic characteristics and increase the aircraft's radar cross-section. Therefore, there is an urgent need for an antenna design that balances electrical and aerodynamic requirements. Conformal antennas are coated on or embedded within the surface of a carrier, conforming to the carrier's surface and maintaining structural consistency. This maximizes space utilization, minimizes impact on the carrier's aerodynamic performance, and allows for larger array apertures. Existing conformal antenna array layouts place planar antenna arrays directly onto the aircraft surface. This requires highly flexible and deformable antenna substrates, increasing antenna design and processing costs. Furthermore, large-format antenna arrays cannot adhere closely to the aircraft surface, reducing conformality and significantly impacting the aircraft's aerodynamic shape.

[0003] The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Summary of the Invention

[0004] The present invention proposes an antenna array for conforming to the irregular surface of an aircraft and a layout method thereof. By conforming individual antennas on the irregular curved surface to form a conformal antenna array, the antenna manufacturing cost is reduced and the conformal effect of the antenna is improved.

[0005] The antenna array layout method for conformal aircraft irregular surface includes the following steps:

[0006] In the first step, the initial parameters of the planar antenna array are given, which include the number of elements N and the element position x. n ,y n ;

[0007] In the second step, the special-shaped surface of the aircraft is converted into a two-dimensional surface, and the conformal surface array factor is obtained according to the mapping relationship. n ,y n Determine the position x′ of the curved antenna array element n , y′ n , z′ n , the normal vector Direction of maximum principal curvature radius and the maximum principal curvature radius k 1n , direction of minimum principal curvature radius and the minimum principal curvature radius k 2n ;

[0008] In the third step, according to the position x′ of the curved antenna element n , y′ n , z′ n Perform surface conformal simulation on a single planar antenna, using the normal vector Place the antenna element for the normal vector, along the direction of the minimum principal curvature radius Conformal, the cylinder radius is k 2n , and then simulate to get the far-field radiation pattern of a single antenna

[0009] In the fourth step, all antenna far-field radiation patterns are synthesized according to the position of the curved antenna array element to obtain the total field pattern function I n is the incentive distribution, is the unit direction diagram; λ is the wavelength, θ is the pitch angle, is the azimuth.

[0010] In the fifth step, it is determined whether the far-field radiation pattern of the antenna meets the design specifications. If not, the process returns to the third step and continues to optimize the planar antenna array factors until the design specifications are met.

[0011] In the method described, in the first step, the planar antenna is a patch antenna, the planar antenna array is a rectangular grid rectangular boundary array, and the array element spacing is

[0012] In the method, in the second step, projection mapping, parameterized mapping, affine transformation, surface fitting or texture mapping is used to establish a mapping relationship between the surface and the plane, x′ n =f1(x n ,y n ), y′ n =f2(x n ,y n ), z′ n =f3(x n ,y n ).

[0013] In the method described, in the third step, a numerical method is used to simulate a single planar antenna at the position x′ of the curved antenna array element. n , y′ n , z′ n After performing conformal operation at , a conformal antenna unit is obtained.

[0014] In the method, the numerical method includes finite element method, finite difference time domain method or moment method.

[0015] In the method, in the fourth step, all antenna far-field radiation patterns are synthesized based on array theory methods.

[0016] In the method, in the fifth step, the conformal curved array factor and the position of the curved antenna array element are iteratively optimized to meet the design specifications.

[0017] In the method, in the fifth step, the coaxial line and the power divider are installed inside the aircraft and connected to the patch antenna that is conformal to the special-shaped surface of the aircraft by mechanical fixing or gluing.

[0018] In the method, in the fifth step, various communication indicators of the aircraft conformal antenna array are tested based on the air-to-ground communication test system to iteratively optimize the conformal curved array factor and the curved antenna array element position.

[0019] An antenna array conforming to an aircraft's irregular surface is formed by using the layout method of the antenna array conforming to an aircraft's irregular surface.

[0020] Beneficial effects

[0021] The present invention designs the antenna array factor, including the spacing and number of array elements, to obtain a planar antenna array that meets the requirements; then, the irregular surface is equidistantly converted to a two-dimensional plane to obtain a mapping relationship between the two, and the array factor obtained previously is directly applied to the converted two-dimensional plane. The array factor of the converted two-dimensional curved surface is used to calculate the array factor of the antenna on the irregular curved surface. According to the curved surface array factor, a single antenna is conformally simulated on the irregular curved surface. Then, the radiation parameters of the curved antenna array are obtained through the antenna array synthesis method. By iteratively optimizing the planar array factor design, various design indicators are achieved. Finally, the coaxial line and power divider are installed inside the aircraft and connected to the patch antenna on the aircraft surface. The feasibility of the antenna scheme is verified according to the test system scheme. The present method can effectively solve the problem of large-area antenna arrays being attached to irregular curved surfaces when conforming, enhance the consistency between the antenna array and the curved surface, and ensure the aerodynamic shape of the aircraft surface while meeting the radio frequency performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 1. A schematic diagram of steps of a method for placing an antenna array conformally on an aircraft's irregularly shaped surface according to one embodiment of the present invention;

[0023] Figure 2 is a schematic diagram of a planar antenna array according to an embodiment of the present invention;

[0024] Figure 3is a schematic diagram of projection mapping of a planar antenna array according to an embodiment of the present invention;

[0025] Figure 4 is a schematic diagram of a conformally bent antenna unit according to an embodiment of the present invention;

[0026] Figure 5 is a schematic diagram of a special-shaped curved surface handpiece according to one embodiment of the present invention;

[0027] Figure 6 is a schematic diagram of conformal testing of a curved antenna array according to an embodiment of the present invention;

[0028] Figure 7 is a schematic diagram of an antenna array power divider according to an embodiment of the present invention;

[0029] Figure 8 1 is a schematic diagram of a conformal antenna array test system framework according to an embodiment of the present invention.

[0030] Various other advantages and benefits of the present invention will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are intended only to illustrate preferred embodiments and are not to be construed as limiting the present invention. It should be understood that the drawings described below are merely examples of the present invention, and that those skilled in the art will be able to derive other drawings from these drawings without inventive effort. Throughout the drawings, identical reference numerals are used to denote identical components. DETAILED DESCRIPTION

[0031] The following will refer to the attached Figures 1 to 8 Specific embodiments of the present invention will now be described in greater detail. Although specific embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention may be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to facilitate a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0032] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction. As mentioned throughout the specification and claims, "including" or "comprising" is an open term, so it should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the present invention, but the description is based on the general principles of the specification and is not intended to limit the scope of the invention. The scope of protection of the present invention shall be as defined in the attached claims.

[0033] To facilitate understanding of the embodiments of the present invention, further explanation will be given below using specific embodiments as examples in conjunction with the accompanying drawings, and the accompanying drawings do not constitute a limitation on the embodiments of the present invention.

[0034] like Figures 1 to 7 As shown, the antenna array layout method for conforming to the aircraft's irregular surface includes the following steps:

[0035] In the first step (S1), the initial parameters of the planar antenna array are given, which include the number of elements N and the element position x n ,y n ;

[0036] In the second step (S2), the special-shaped surface of the aircraft is converted into a two-dimensional surface, and the conformal surface array factor is obtained according to the mapping relationship. n ,y n Determine the position x′ of the curved antenna array element n , y′ n , z′ n , the normal vector Direction of maximum principal curvature radius and the maximum principal curvature radius k 1n , direction of minimum principal curvature radius and the minimum principal curvature radius k 2n ;

[0037] In the third step (S3), according to the position x′ of the curved antenna element n , y′ n , z′ n Perform surface conformal simulation on a single planar antenna, using the normal vector Place the antenna element for the normal vector, along the direction of the minimum principal curvature radius Conformal, the cylinder radius is k 2n , and then simulate to get the far-field radiation pattern of a single antenna

[0038] In the fourth step (S4), all antenna far-field radiation patterns are synthesized according to the position of the curved antenna array element to obtain the total field pattern function I n is the incentive distribution, is the unit direction diagram; λ is the wavelength, θ is the pitch angle, is the azimuth.

[0039] In the fifth step (S5), it is determined whether the far-field radiation pattern of the antenna meets the design specifications. If not, the process returns to the third step (S3) and continues to optimize the planar antenna array factors until the design specifications are met.

[0040] In a preferred embodiment of the method, in the first step (S1), the planar antenna is a patch antenna, the planar antenna array is a rectangular grid rectangular boundary array, and the array element spacing is θ0 is the elevation angle of the maximum beam direction, λ min is the minimum wavelength of the antenna.

[0041] In a preferred embodiment of the method, in the second step (S2), projection mapping, parameterized mapping, affine transformation, surface fitting or texture mapping is used to establish a mapping relationship between the surface and the plane, x′ n =f1(x n ,y n ), y′ n =f2(x n ,y n ), z′ n =f3(x n ,y n ).

[0042] In a preferred embodiment of the method, in the third step (S3), a numerical method is used to simulate a single planar antenna at the position x′ of the curved antenna array element. n , y′ n , z′ n After performing conformal operation at , a conformal antenna unit is obtained.

[0043] In a preferred embodiment of the method, the numerical method includes a finite element method, a finite difference time domain method or a moment method.

[0044] In a preferred embodiment of the method, in the fourth step (S4), the far-field radiation patterns of all antennas are synthesized based on an array theory method.

[0045] In a preferred embodiment of the method, in the fifth step (S5), the conformal curved array factor and the curved antenna element position are iteratively optimized to meet the design specifications.

[0046] In a preferred embodiment of the method, in the fifth step (S5), the coaxial line and the power divider are installed inside the aircraft and connected to the patch antenna that is conformal to the aircraft's irregular surface by mechanical fixing or gluing.

[0047] In a preferred embodiment of the method, in the fifth step (S5), various communication indicators of the aircraft conformal antenna array are tested based on the air-to-ground communication test system to iteratively optimize the conformal curved array factor and the curved antenna array element position.

[0048] An antenna array conforming to an aircraft's irregular surface is formed by using the layout method of the antenna array conforming to an aircraft's irregular surface.

[0049] To further illustrate the method of the present invention, Figure 1 This is a schematic diagram of the steps in the antenna array layout method for conformal aircraft irregular surfaces. First, antenna units that meet the performance requirements are selected, and then the antenna array factor is designed, including the spacing and number of array elements, to obtain a planar antenna array that meets the requirements; then the irregular surface is isometrically converted to a two-dimensional plane to obtain the mapping relationship between the two, and the array factor obtained previously is directly applied to the converted two-dimensional plane. The array factor of the converted two-dimensional surface is used to calculate the array factor of the antenna on the irregular surface. Figure 1 As shown in the figure, a single antenna is conformally simulated on an irregular curved surface according to the curved array factor, and then the radiation parameters of the curved antenna array are obtained through the antenna array synthesis method. If the design indicators are met, the irregular curved surface antenna array is tested. If the design indicators are not met, the planar array factor design is optimized.

[0050] Figure 2 3 is a schematic diagram of a planar antenna array according to an embodiment of the present invention, wherein the antenna array is a 16-element uniform array. Figure 3 This is a schematic diagram of projection mapping of a planar antenna array according to an embodiment of the present invention. By projecting the antenna elements in the array onto a curved surface, it is sufficient to ensure that the center of each antenna element is on the curved surface. In this case, the center of the antenna element is the position x′ of the curved antenna array element. n , y′ n , z′ n ; Figure 4 : is a schematic diagram of a conformal bending antenna unit according to an embodiment of the present invention, wherein the normal direction and conformal direction of the antenna unit are and Corresponding to the above third step (S3) and The cylindrical conformal radius is R, which corresponds to k in the third step (S3) above. 2n . Figure 5 Schematic diagram of a special-shaped curved surface handpiece according to one embodiment of the present invention. Figure 6 This is a schematic diagram of a conformal test of a curved antenna array according to an embodiment of the present invention. The position of each patch is obtained by the aforementioned surface conformal factor. Each antenna is discretely distributed and fed separately by a coaxial line, which is finally connected to a power divider. Figure 7 Schematic diagram of an antenna array power divider according to an embodiment of the present invention. 16 antenna units require a one-sixteenth-equal power divider, which is a second-order Wilkinson power divider.

[0051] In a preferred embodiment of the method, in the first step S1: the antenna is a patch antenna, and the planar antenna array is as follows Figure 2 The 16-element rectangular grid rectangular boundary array, in order to ensure that the maximum scanning angle does not appear grating lobe, the array element spacing requirement is designed to be

[0052] In a preferred embodiment of the method, in the second step S2: a mapping relationship between a curved surface and a plane is established, x′ n =f1(x n ,y n ), y′ n =f2(x n ,y n ), z′ n =f3(x n ,y n ), projection mapping, parameterized mapping, affine transformation, surface fitting, texture mapping and other methods can be used.

[0053] In a preferred embodiment of the method, in the third step S3: Figure 3 As shown, a single antenna is at the curved array element position x′ n , y′ n , z′ n After performing conformal operations at the points, the curved antenna unit is obtained, and numerical methods such as the finite element method, finite difference time domain method, and moment method are used to simulate a single antenna.

[0054] In a preferred embodiment of the method, in the fourth step S4: all antenna far-field radiation patterns are synthesized based on an array theory method.

[0055] In a preferred embodiment of the method, in the fifth step S5: the specific parameter of the iterative optimization of the planar array factor is the array element position of the antenna unit, and during the test, each patch antenna is connected to the power divider via a coaxial line, and the coaxial line and the power divider are installed inside the aircraft. During the test, each patch antenna is conformal to the special-shaped surface of the aircraft by mechanical fixation or bonding, and all discrete antenna units together constitute a conformal antenna array.

[0056] Furthermore, an air-to-ground communication test system was built to verify the common characteristics of the antenna, the reconfigurable characteristics of the frequency points, and the communication indicators through communication tests at target distances in an air-to-ground environment. Specifically, the test system mainly consists of two parts: an air system and a ground system. The air system is the transmitter of the communication test system, and the ground system is the receiver. To meet the needs of common antenna testing, air-to-ground communication transmission is achieved at approximately 10 frequency points near 5GHz. At the same time, to cooperate with testing at different frequency points, the air-to-ground system is also equipped with a LoRa-based control information transceiver system, with ground transmission and air reception for coordinated working frequency points of air-to-ground communication testing. The system workflow includes the following: ① The user determines the communication test frequency (selected from 10 predefined frequencies), and the drone flies to the predetermined route; ② The selected frequency is mapped to 4 bits of information and input into the ground LoRa module, which is then synchronized to the ground receiver; ③ The ground LoRa transmitter transmits the 4 bits of information to the airborne LoRa receiver; ④ The airborne LoRa parses the 4 bits of information, one channel of which is input into the switch module via serial-to-parallel conversion to control the four switch states, and another channel is input into the USRP, which is mapped to the RF operating frequency through a table lookup; ⑤ The airborne USRP inputs the RF and switch states into the antenna under test, and the relevant communication parameters (modulation, spread spectrum, etc.) are configured to transmit the communication signal; ⑥ The ground receiver receives the signal at the corresponding frequency, one channel of which is input into a spectrum analyzer to observe the signal spectrum, and another channel is input into the ground USRP for data processing. Communication-related indicators (communication rate, bit error rate, constellation diagram, etc.) are analyzed and output, and displayed in the GUI along with the drone's position information. ⑦ Repeat these steps to complete communication testing at other operating frequencies.

[0057] Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the above-mentioned specific embodiments and application fields. The above-mentioned specific embodiments are merely illustrative and instructive, and are not restrictive. A person skilled in the art, guided by this specification and without departing from the scope of protection of the claims of the present invention, may also devise various forms, all of which fall within the scope of protection of the present invention.

Claims

1. A method for placing an antenna array conformally to an aircraft's irregularly shaped surface, characterized in that: It includes the following steps: In the first step (S1), the initial parameters of the planar antenna array are given, which include the number of elements N and the element position x n ,y n ; In the second step (S2), the special-shaped surface of the aircraft is converted into a two-dimensional surface, and the conformal surface array factor is obtained according to the mapping relationship. n ,y n Determine the position x′ of the curved antenna array element n , y′ n , z′ n , the normal vector Direction of maximum principal curvature radius and the maximum principal curvature radius k 1n , direction of minimum principal curvature radius and the minimum principal curvature radius k 2n ; In the third step (S3), according to the position x′ of the curved antenna element n , y′ n , z′ n Perform surface conformal simulation on a single planar antenna, using the normal vector Place the antenna element for the normal vector, along the direction of the minimum principal curvature radius Conformal, the cylinder radius is k 2n , and then simulate to get the far-field radiation pattern of a single antenna In the fourth step (S4), all antenna far-field radiation patterns are synthesized according to the position of the curved antenna array element to obtain the total field pattern function I n is the incentive distribution, is the unit direction diagram; λ is the wavelength, θ is the pitch angle, is the azimuth; In the fifth step (S5), it is determined whether the far-field radiation pattern of the antenna meets the design specifications. If not, the process returns to the third step (S3) and continues to optimize the planar antenna array factors until the design specifications are met.

2. The method according to claim 1, characterized in that Preferably, in the third step (S3), a numerical method is used to simulate a single planar antenna at the position x′ of the curved antenna array element. n , y′ n , z′ n After performing conformal operation at , a conformal antenna unit is obtained.

3. The method according to claim 2, characterized in that The numerical method includes finite element method, finite difference time domain method or moment method.

4. The method according to claim 1, wherein In the fourth step (S4), the far-field radiation patterns of all antennas are synthesized based on array theory methods.

5. The method according to claim 1, wherein In the fifth step (S5), the conformal array factor and the position of the curved antenna elements are iteratively optimized to meet the design specifications.

6. The method according to claim 1, wherein In the fifth step (S5), the coaxial line and the power divider are installed inside the aircraft and connected to the patch antenna that is conformal to the special-shaped surface of the aircraft by mechanical fixing or gluing.

7. The method according to claim 1, characterized in that In the fifth step (S5), various communication indicators of the aircraft conformal antenna array are tested based on the air-to-ground communication test system to iteratively optimize the conformal curved array factor and the position of the curved antenna array elements.

8. An antenna array for conforming to an aircraft's irregularly shaped surface, characterized in that: The antenna array is formed by the layout method for an antenna array conforming to an aircraft's irregular surface as claimed in any one of claims 1 to 7.

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