Array antenna pattern comprehensive optimization method and system based on far-field compensation

Abstract

The invention discloses an array antenna pattern comprehensive optimization method and system based on far-field compensation, and belongs to the technical field of microwaves, and the method comprises the following steps: S1, carrying out the near-field time-sharing collection of a line source; s2, performing far field calculation and feature extraction; s3, compensating the amplitude phase of the line source; s4, adding amplitude and phase weights; and S5, synthesizing lobes. The method is suitable for phased-array antennas in any shapes, effectively solves the problem of inconsistency compensation of a combined line source, provides a new way for low-sidelobe directional diagram synthesis of the phased-array antennas, unifies radiation characteristics of the antennas in any shapes to a far-field category, avoids a tedious solution process that phase centers are not coplanar during near-field processing, has universality, and can be widely applied to the field of low-sidelobe directional diagrams of the phased-array antennas. The device is worthy of popularization and use.

Description

Technical Field

[0001] The present invention relates to the field of microwave technology, and in particular to a method and system for comprehensive optimization of array antenna patterns based on far-field compensation. Background Art

[0002] Antenna pattern synthesis plays an important role in antenna optimization design. It is crucial that the designed antenna achieves the desired radiation characteristics. The conventional requirement for antenna pattern is that the antenna has no side lobes in a specific direction. Other requirements include that the pattern presents a desired shape in a specific direction, such as narrowed beam or low side lobes. The realization of the above requirements is based on the optimization of antenna structural parameters, external dimensions and excitation distribution.

[0003] Antenna pattern synthesis often requires a simplified approximation of the model, and then matching the analytical model with the physical antenna model. Antenna lobe synthesis can be divided into three categories. The first category refers to the appearance of zero depth in a specific radiation direction of the antenna. The method proposed by Schelkunoff can achieve this type of requirement; the other category requires the pattern to present the desired shape in the entire visible area, that is, beamforming, which can be achieved through methods such as Fourier transform. The third category of requirements includes beam narrowing and low side lobes, and methods such as Chebyshev can solve this type of requirement. The low side lobe characteristic is an important characteristic of radar and directly affects the working efficiency of the radar.

[0004] Radars often use a one-dimensional scanning system and a network synthesis method in the other dimension. This architecture can reduce active channels while achieving high gain and large detection distance, thereby reducing costs. Due to the introduction of the synthesis system, there are inconsistencies between different synthesized line sources. Conventional unit-level correction can remove the inconsistency between units by calibrating each unit in a darkroom. For synthetic line sources, their phase center cannot be equivalent to a point in the near field, so their inconsistency cannot be compensated in the near field. If the inconsistency cannot be compensated, it will be impossible to weight the array to obtain low sidelobe characteristics, which will seriously affect the working efficiency of the radar. To this end, a comprehensive optimization method and system for array antenna patterns based on far-field compensation are proposed. Summary of the invention

[0005] The technical problem to be solved by the present invention is how to effectively compensate for the inconsistency of line sources and ultimately achieve a low sidelobe pattern, and provides a comprehensive optimization method for array antenna patterns based on far-field compensation.

[0006] The present invention solves the above technical problems through the following technical solutions, and the present invention comprises the following steps:

[0007] S1: Line source near-field time-sharing acquisition

[0008] Use a time-sharing acquisition device to collect the near-field data of N combined line sources, and obtain the near-field test data of each combined line source. Among them, the combined line source includes antennas in any form;

[0009] S2: Far-field extrapolation and feature extraction

[0010] Perform near-to-far field transformation on the near-field test data of each combined line source in turn to obtain the far-field pattern of N combined line sources; then extract the field value at the maximum radiation direction of the array plane of each far-field pattern as its eigenvalue;

[0011] S3: Amplitude and phase compensation of line sources

[0012] According to the far-field eigenvalue data of each combined line source extracted, based on the far-field principle, the combined line source is equivalent to an observation point in the far-field area, take the derivative of the eigenvalue of each combined line source, and substitute it as a characteristic quantity into the lobe synthesis process;

[0013] S4: Assignment of amplitude and phase weights

[0014] Use an optimization algorithm to optimize the amplitude a on and phase φ on of each combined line source according to the position of the combined line source to obtain the weights of amplitude and phase;

[0015] S5: Synthesis of lobes

[0016] Based on the extracted characteristic quantities and the weights of amplitude and phase obtained by optimization, obtain the weights of the combined line source, perform weighted superposition on the near-field test data of each antenna element plane according to the weights of the combined line source, obtain the compensated near-field data of the phased array antenna plane, and then perform near-to-far field transformation on this plane near-field data to obtain a low sidelobe pattern.

[0017] Furthermore, in the step S1, the format of the near-field test data of each combined line source is a two-dimensional matrix M, the two dimensions of the matrix are the same as the number of acquisition points of the near-field plane, and the values in the matrix represent the near-field field values.

[0018] Furthermore, in the step S1, through the switching between the channels of the program-controlled switch matrix, cooperate with the near-field data acquisition system of the anechoic chamber probe to collect the near-field test data of the combined line source.

[0019] Furthermore, in the step S2, the eigenvalue is the amplitude a n and phase φ n at the maximum radiation direction of the array plane, where n represents the nth combined line source.

[0020] Furthermore, in the step S3, the characteristic quantity A n is as follows:

[0021]

[0022] Further, in the step S4, the amplitude-phase weight A on is as follows:

[0023]

[0024] Further, in the step S4, the optimization algorithm includes a genetic algorithm or a particle swarm algorithm, and spatial phase difference compensation is performed according to the relative positions of the combined line sources during optimization.

[0025] Further, in the step S5, the combined line source weight A is as follows:

[0026] A = A n ·A on .

[0027] The present invention also provides an array antenna pattern synthesis optimization system based on far-field compensation, which realizes the synthesis and optimization of the array antenna pattern by using the above method, including:

[0028] A near-field time-sharing acquisition module for a line source, which uses time-sharing acquisition equipment to acquire the near-field data of N combined line sources to obtain the near-field test data of each combined line source, where the combined line source includes antennas in any form;

[0029] A far-field calculation and feature extraction module, which is used to perform near-to-far field transformation on the near-field test data of each combined line source in turn to obtain the far-field patterns of N combined line sources; then extract the field value of each far-field pattern at the maximum radiation direction of the array surface as its eigenvalue;

[0030] A line source amplitude-phase compensation module, which is used to, based on the extracted far-field eigenvalue data of each combined line source and the far-field principle, equivalent the combined line source to an observation point in the far-field area, take the derivative of the eigenvalue of each combined line source, and use it as a feature quantity to substitute into the lobe synthesis process;

[0031] An amplitude-phase weight assignment module, which is used to use an optimization algorithm to optimize the amplitude a on and phase φ on of each combined line source according to the position of the combined line source to obtain the amplitude-phase weight;

[0032] A synthesized lobe module, which is used to obtain the combined line source weight based on the extracted feature quantity and the optimized amplitude-phase weight, perform weighted superposition on the near-field test data of each antenna element plane according to the combined line source weight to obtain the compensated phased array antenna plane near-field data, and then perform near-to-far field transformation on this plane near-field data to obtain a low sidelobe pattern.

[0033] The present invention has the following advantages compared with the prior art: The method and system for comprehensive optimization of the array antenna pattern based on far-field compensation utilize a time-sharing acquisition device and a planar near-field acquisition system. First, the near-field data of the combined line source is obtained, then the far-field pattern is calculated and the characteristic values in specific directions are extracted. Next, the characteristic amplitude-phase values are obtained by processing the characteristic values, and then the amplitude-phase of the combined line source is optimized by combining the position information of the combined line source to obtain weights. Finally, the characteristic amplitude-phase values and weights are substituted into lobe synthesis to obtain a low sidelobe far-field pattern. It is applicable to any phased array antenna, effectively solves the problem of inconsistency compensation of the combined line source, provides a new way for the synthesis of the low sidelobe pattern of the phased array antenna, and unifies the radiation characteristics of antennas of any shape into the far-field category, avoiding the cumbersome solution process of non-coplanar phase centers during near-field processing. At the same time, it effectively avoids the expected deviation caused by errors during the application of theory to the engineering process: processing and assembly errors lead to differences between the actually produced antenna and the simulation design model, resulting in differences between different line sources. Radar often requires beamforming. When the number of combined line source units is large, the debugging workload of the synthesis network is large, and the inconsistency between adjacent synthesis networks is large. The present invention can effectively relieve the debugging pressure of complex combined networks, reduce the inconsistency threshold, improve the product yield and shorten the development cycle, making a great contribution to the development of mass-produced products and worthy of being promoted and used. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a flowchart of the method for comprehensive optimization of the array antenna pattern based on far-field compensation in Embodiment 1 of the present invention;

[0035] Figure 2 is the azimuth scan 30° azimuth plane pattern of the array antenna without compensation and optimized weighting at 6 GHz in Embodiment 2 of the present invention;

[0036] Figure 3 is the azimuth scan 30° azimuth plane pattern obtained by the genetic algorithm at 6 GHz in Embodiment 2 of the present invention;

[0037] Figure 4 is the azimuth scan 30° azimuth plane pattern of the phased array antenna after compensation at 6 GHz in Embodiment 2 of the present invention;

[0038] Figure 5 is the normal azimuth plane pattern of the array antenna without compensation and optimized weighting at 10 GHz in Embodiment 3 of the present invention;

[0039] Figure 6 is the normal azimuth plane pattern obtained by the genetic algorithm at 10 GHz in Embodiment 3 of the present invention;

[0040] Figure 7 is the far-field pattern of the array antenna in the normal direction at 10 GHz after compensation in Embodiment 3 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0041] The following is a detailed description of the embodiments of the present invention. These embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0042] Embodiment 1

[0043] As Figure 1 shown, it is a flowchart of the pattern synthesis optimization method of the present invention. This embodiment provides a technical solution: an array antenna pattern synthesis optimization method based on far-field compensation, including the following steps:

[0044] S1: Near-field time-sharing acquisition of line sources

[0045] With the help of a time-sharing acquisition device, the near-field data of N combined line sources are acquired to obtain the near-field test data of each combined line source. The format of the near-field test data of each combined line source is a two-dimensional matrix M. The two dimensions of the matrix are the same as the number of acquisition points on the near-field plane, and the values in the matrix represent the near-field field values; among them, the combined line source includes antennas in any form.

[0046] S2: Far-field calculation and feature extraction

[0047] Perform near-to-far field transformation on the near-field test data of each combined line source in turn to obtain the far-field patterns of N combined line sources. The far-field pattern is the field value in a two-dimensional coordinate system, which is generally set as the (θ, φ) coordinate system without special requirements; extract the field value at a specific direction of each far-field pattern as its eigenvalue; the extracted data is the amplitude a n and phase φ n at a certain direction in the far field, where n represents the nth combined line source.

[0048] S3: Amplitude-phase compensation of line sources

[0049] According to the amplitude-phase data at the far field of each combined line source extracted, based on the far-field principle, the combined line source can be equivalent to an observation point in the far-field area. Take the derivative of the eigenvalue of each combined line source and use it as a characteristic quantity to substitute into the lobe synthesis process. The characteristic quantity A n is as follows:

[0050]

[0051] S4: Assignment of amplitude-phase weights

[0052] To achieve low sidelobe performance, with the help of an optimization algorithm, optimize the amplitude a on and phase φ on of each combined line source according to the position of the combined line source to obtain the weights A on of the amplitude-phase:

[0053]

[0054] S5: Composite lobe

[0055] Based on the above-extracted characteristic quantities and the weights of the amplitude-phase obtained through optimization, obtain the combined path source weight A:

[0056] A = A n ·A on ;

[0057] Based on the extracted characteristic quantities and the weights of the amplitude-phase obtained through optimization, obtain the combined path source weight. According to the combined path source weight, perform weighted superposition on the plane near-field test data of each unit, obtain the compensated phased array antenna plane near-field data, and then perform near-to-far field transformation on the plane near-field data to obtain a low sidelobe pattern.

[0058] This method is applicable to any phased array antenna, effectively solves the problem of inconsistency compensation of the combined path source, provides a new way for the synthesis of the low sidelobe pattern of the phased array antenna, and unifies the radiation characteristics of any shaped antenna into the far-field category, avoiding the cumbersome solution process of non-coplanar phase centers during near-field processing. At the same time, it effectively avoids the expected deviation caused by errors during the application of theory to the engineering process: the differences between different line sources caused by the differences between the actually produced antenna and the simulation design model due to processing and assembly errors.

[0059] In this embodiment, in the step S1, the method of time-sharing acquisition of the combined path source near-field data can select the fast switching between the channels of the program-controlled switch matrix and cooperate with the anechoic chamber probe plane near-field data acquisition system for acquisition. Specifically, set the scanning range of the probe to be within a plane at a set distance from the antenna array surface, discretize the plane into periodically arranged scanning points. When the probe stays at each scanning point, use the program-controlled switch to switch the channels corresponding to each combined path source and acquire the plane near-field test data of each combined path source.

[0060] In this embodiment, in the step S2, take a certain angle within the main lobe range in a specific direction. Since different combined path sources have similar characteristics near the array scanning angle within the main lobe range and are less affected by spatial scattering energy, it can be used as a characteristic to represent the electrical performance inconsistency between different combined path sources; if there are no special requirements, the specific direction can select the maximum radiation direction of the array surface.

[0061] In this embodiment, in the step S3, the eigenvalue can be used as the basis for detecting the performance of the combined path source. If the far-field level of a certain combined path source is much lower than that of the other combined path sources, this combined path source can be marked and replaced with a spare part during installation.

[0062] In this embodiment, in the step S4, the optimization algorithm can select genetic algorithm, particle swarm algorithm, etc., and perform spatial phase difference compensation according to the relative positions of the combined line sources during optimization.

[0063] This embodiment also provides an array antenna pattern synthesis and optimization system based on far-field compensation, including:

[0064] A line source near-field time-sharing acquisition module, which is used to obtain the planar near-field test data of each combined line source of the phased array antenna, and save the planar near-field test data for compensation and synthesis of the lobe;

[0065] A far-field calculation and feature extraction module, which is used to calculate the far-field of each combined line source, and extract the field values in specific directions of the far-field as eigenvalues to participate in array surface compensation;

[0066] A line source amplitude-phase compensation module, which is used to process the eigenvalues and has the state of synthesizing the lobe;

[0067] An amplitude-phase weight assignment module, which is used to obtain the weights with low sidelobe characteristics, optimize the sidelobes of the phased array antenna pattern, and obtain the optimized amplitude-phase;

[0068] A synthesized lobe module, which is used to perform weighted superposition on the planar near-field test data of each unit, obtain the compensated planar near-field data of the phased array antenna, and then perform near-to-far field transformation on the planar near-field data to obtain a low-sidelobe pattern;

[0069] A central processing module, which is used to send instructions to other modules to complete related actions;

[0070] The line source near-field time-sharing acquisition module, the far-field calculation and feature extraction module, the line source amplitude-phase compensation module, the amplitude-phase weight assignment module, and the synthesized lobe module are all electrically connected to the central processing module.

[0071] Embodiment 2

[0072] In this embodiment, the array antenna pattern synthesis and optimization method based on far-field compensation is used to optimize a certain complex conformal array antenna. The conformal surface is intercepted from the nose of an aircraft. The antenna operates in the frequency band of 4 GHz - 6 GHz. The array surface scale is 24 (azimuth) * 12 (elevation), and the antenna polarization direction is horizontal polarization. It is required that the azimuth sidelobe level is lower than -20 dB when the azimuth scans 30°.

[0073] First, the conformal array antenna is set up in a microwave darkroom, and the near-field test data of each conformal unit when it is excited separately is collected in time-sharing mode with the help of a switch matrix and a planar near-field acquisition system. Then, the near-field to far-field transformation is performed to obtain the far-field radiation pattern, and the far-field amplitude and phase values at an azimuth of 30° are extracted as the eigenvalues of each antenna unit. The eigenvalue is then subjected to derivative processing, and the unit amplitude and phase are optimized based on the position information of the conformal unit with the help of a genetic algorithm to obtain the optimized amplitude and phase of each conformal antenna.

[0074] like Figure 2 As shown, it is the azimuth scanning 30° azimuth plane radiation pattern of the array antenna at 6GHz without compensation and optimized weighting.

[0075] The genetic algorithm is used to optimize the side lobes of the scanning pattern of the conformal array antenna and obtain the optimized amplitude. Figure 3 As shown, the azimuth scanning 30° azimuth plane radiation pattern obtained by the genetic algorithm at 6GHz.

[0076] Finally, substitute the eigenvalue and optimize the amplitude and phase to perform lobe synthesis. Figure 4 The figure shows the azimuth scanning 30° azimuth plane radiation pattern of the 6GHz compensated phased array antenna. The near-field test data of each unit plane collected above are superimposed according to the compensation coefficient and the optimized amplitude to obtain the compensated array plane near-field data, and the far-field radiation pattern is obtained by performing near-field to far-field transformation.

[0077] Embodiment 3

[0078] The planar phased array antenna selected in this embodiment is composed of 36 column line sources, the antenna operates in the 8GHz-10GHz frequency band, and the array size in the elevation direction is 24 rows. It is required that the azimuth sidelobe level is lower than -25dB in the normal direction.

[0079] like Figure 5 As shown, the normal azimuth plane radiation pattern of the array antenna at 10GHz without compensation and optimized weighting. First, the near-field test data of each line source is collected in a microwave darkroom with the help of a switch matrix when each line source is excited separately, and then the near-field and far-field transformation of all line sources is performed.

[0080] Then, the far-field amplitude and phase values of each line source at the normal direction are extracted as its eigenvalues. Then, the optimized amplitude and phase values under the normal state are obtained with the help of genetic algorithm.

[0081] like Figure 6 As shown, this is the normal azimuth plane pattern obtained by the genetic algorithm at 10 GHz.

[0082] like Figure 7As shown, it is the far-field pattern in the normal direction of the array antenna after 10GHz compensation. According to the compensation coefficient and the optimized amplitude and phase, the near-field test data of each line source plane collected above are superimposed to obtain the near-field data of the compensated array plane, and the near-to-far field transformation is performed to obtain the far-field pattern.

[0083] In summary, for the method and system for comprehensive optimization of the array antenna pattern based on far-field compensation in the above three groups of embodiments, by using the time-sharing acquisition device and the planar near-field acquisition system, first obtain the near-field test data of the combined line source, then calculate the far-field pattern and extract the characteristic values in a specific direction, then process the characteristic values to obtain the characteristic amplitude-phase values, and then combine the position information of the combined line source to optimize the amplitude and phase of the combined line source to obtain the weights. Finally, substitute the characteristic amplitude-phase values and the weights into the lobe synthesis to obtain the low sidelobe far-field pattern, which is applicable to any phased array antenna, effectively solves the problem of inconsistency compensation of the combined line source, provides a new way for the synthesis of the low sidelobe pattern of the phased array antenna, and unifies the radiation characteristics of any shaped antenna into the far-field category, avoiding the cumbersome solution process of non-coplanar phase centers during near-field processing. At the same time, it effectively avoids the expected deviation caused by errors during the application of theory to the engineering process: the differences between different line sources caused by the differences between the antennas actually produced and the simulation design model due to processing and assembly errors. Radar often requires beamforming. When the number of combined line source units is large, the debugging workload of the synthesis network is large, and the inconsistency between adjacent synthesis networks is large. The present invention can effectively relieve the debugging pressure of the complex combined network, reduce the inconsistency threshold, improve the product yield and shorten the development cycle, and make a great contribution to the development of mass-produced products, and is worthy of being popularized and used.

[0084] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for comprehensive optimization of the radiation pattern of an array antenna based on far-field compensation, characterized in that It includes the following steps: S1: Near-field time-division acquisition of line sources Use a time-division acquisition device to acquire the near-field data of N combined line sources, and obtain the near-field test data of each combined line source. Among them, the combined line source includes antennas in any form; S2: Far-field calculation and feature extraction Perform near-to-far field transformation on the near-field test data of each combined line source in sequence to obtain the far-field patterns of N combined line sources; then extract the field value of each far-field pattern at the maximum radiation direction of the array plane as its eigenvalue; S3: Amplitude-phase compensation of line sources According to the extracted far-field eigenvalue data of each combined line source, based on the far-field principle, equivalent the combined line source to an observation point in the far-field area, take the derivative of the eigenvalue of each combined line source, and substitute it as a feature quantity into the lobe synthesis process; S4: Assignment of amplitude-phase weights Using an optimization algorithm, optimize the amplitude a of each combined path source according to the position of the combined path source on and the phase φ on to obtain the weight values of the amplitude and phase; S5: Synthesis of lobes Based on the extracted feature quantities and the optimized amplitude-phase weights, obtain the weights of the combined line sources. According to the weights of the combined line sources, perform weighted superposition on the near-field test data of each antenna element plane to obtain the compensated near-field data of the phased array antenna plane, and then perform near-to-far field transformation on this near-field data to obtain a low sidelobe pattern.

2. The method for comprehensively optimizing the radiation pattern of an array antenna based on far-field compensation according to claim 1, wherein In the step S1, the format of the near-field test data of each combined line source is a two-dimensional matrix M. The two dimensions of the matrix are the same as the number of acquisition points on the near-field plane, and the values in the matrix represent the near-field field values.

3. The method for comprehensively optimizing the radiation pattern of an array antenna based on far-field compensation according to claim 2, wherein In the step S1, through the switching between the channels of the program-controlled switch matrix, cooperate with the near-field data acquisition system of the anechoic chamber probe plane to perform the acquisition work of the near-field test data of the combined line source.

4. The method for comprehensively optimizing the radiation pattern of an array antenna based on far-field compensation according to claim 1, wherein In the step S2, the eigenvalue is the amplitude a at the maximum radiation direction of the array surface n and the phase φ n , where n represents the nth combined path source.

5. The method for comprehensively optimizing the pattern of an array antenna based on far-field compensation according to claim 4, wherein In the step S3, the feature quantity A n is as follows:

6. The method for comprehensively optimizing the radiation pattern of an array antenna based on far-field compensation according to claim 5, characterized in that, In the step S4, the amplitude-phase weight value A on is as follows:

7. The method for comprehensively optimizing the radiation pattern of an array antenna based on far-field compensation according to claim 1, wherein In the step S4, the optimization algorithm includes a genetic algorithm or a particle swarm algorithm. During optimization, spatial phase difference compensation is performed according to the relative positions of the combined line sources.

8. The method for comprehensively optimizing the radiation pattern of an array antenna based on far-field compensation according to claim 6, wherein In the step S5, the weights A of the combined line sources are as follows: A = A n ·A on 。 9. An array antenna pattern synthesis and optimization system based on far-field compensation, characterized in that Implementing the pattern synthesis optimization of the array antenna by using the method according to any one of claims 1 to 8, including: A near-field time-division acquisition module for line sources, which uses a time-division acquisition device to acquire the near-field data of N combined line sources, and obtains the near-field test data of each combined line source. Among them, the combined line source includes antennas in any form; A far-field calculation and feature extraction module, which is used to perform near-to-far field transformation on the near-field test data of each combined line source in sequence to obtain the far-field patterns of N combined line sources; then extract the field value of each far-field pattern at the maximum radiation direction of the array plane as its eigenvalue; A line source amplitude-phase compensation module, which is used to, according to the extracted far-field eigenvalue data of each combined line source, based on the far-field principle, equivalent the combined line source to an observation point in the far-field area, take the derivative of the eigenvalue of each combined line source, and substitute it as a feature quantity into the lobe synthesis process; Amplitude-phase weight assignment module, which is used to optimize the amplitude a of each combined path source according to the position of the combined path source by using an optimization algorithm on and the phase φ on to obtain the weights of the amplitude and phase; A lobe synthesis module, which is used to, based on the extracted feature quantities and the optimized amplitude-phase weights, obtain the weights of the combined line sources. According to the weights of the combined line sources, perform weighted superposition on the near-field test data of each antenna element plane to obtain the compensated near-field data of the phased array antenna plane, and then perform near-to-far field transformation on this near-field data to obtain a low sidelobe pattern.

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