Orthogonal polarization sparse distribution based array monopulse angle measurement correction method

Abstract

The application discloses a single-pulse angle measurement correction method based on orthogonal polarization sparse distribution, which realizes elimination of single-pulse angle measurement errors caused by array element coupling and array cross polarization through orthogonal polarization sparse distribution at a low cost, and guarantees single-pulse angle measurement precision through three steps of single-polarization array modification, joint polarization constraint based on point constraint and reconstruction of a single-pulse angle measurement model. The method has wide application prospect and stable and reliable performance.

Description

Technical Field

[0001] This invention belongs to the field of single-pulse angle measurement technology, specifically relating to an array single-pulse angle measurement correction method based on orthogonal polarization sparse distribution. Background Technology

[0002] Monopulse angle measurement technology is widely used in radar detection. In practical applications, due to the high engineering quality requirements and high cost of dual-polarized and fully polarized array radars, large-scale application is difficult. Therefore, single-polarized array radar is more widely used in practice. However, because antenna manufacturing processes cannot guarantee the receiving polarization purity of all antennas, and the coupling characteristics between array radar antennas cannot be ignored, when monopulse angle measurement technology is applied to polarized arrays, under large angles of array beam offset normal, array cross-polarization and element antenna coupling will cause distortion of the monopulse angle measurement curve, making it unsuitable for accurate angle measurement.

[0003] To address the single-pulse angle measurement error caused by cross-polarization, "M.Li, X.Wang, J.Dong,

[0004] "Optimal Difference Pattern Synthesis With Polarization Control for Arbitrary Arrays," IEEE Antennas and Wireless Propagation Letters, vol.11, pp.

[0005] In a dual-polarized array system, cross-polarization suppression is applied to the array receiving channel to reduce angle measurement errors. However, residual cross-polarization components that are not completely suppressed make it difficult for the monopulse angle measurement results of this method to escape the influence of incoming wave polarization. This makes it difficult to maintain stable angle measurement accuracy in practical scenarios, and the method is based on a dual-polarized array platform, resulting in high application costs. To address monopulse angle measurement errors, a class of point-constraint-based monopulse angle measurement correction methods exists. (See: "Z.Cheng, Z.He, X.Duan, X.Zhang and B.Liao," *Adaptive Monopulse Approach with Joint LinearConstraints for Planar Array at Subarray Level*, IEEE Transactions on Aerospace and Electronic Systems, vol.54, no.3, pp.1432-1441, June). The "2018" method uses a standard monopulse curve as a benchmark to reduce angle measurement error by ensuring that the linear region of the adaptive monopulse curve remains undistorted. However, this method does not consider the influence of antenna cross-polarization, and in practical applications, the angle measurement error caused by antenna cross-polarization is still not negligible.

[0006] In summary, methods that reduce angle measurement errors by suppressing array cross-polarization cannot completely eliminate its influence. It is necessary to utilize existing technologies to move beyond treating cross-polarization as part of the angle measurement error and address the single-pulse angle measurement errors caused by array cross-polarization and element coupling at a lower cost, ensuring that the angle measurement results are unaffected by the polarization of the incoming target wave. Further research in this area is urgently needed. Summary of the Invention

[0007] The purpose of this invention is to provide an array single-pulse angle measurement correction method based on orthogonal polarization sparse distribution, which eliminates the influence of array cross polarization on angle measurement at a lower cost and ensures the accuracy of single-pulse angle measurement.

[0008] The technical solution adopted in this invention is: an array monopulse angle measurement correction method based on orthogonal polarization sparse distribution, comprising the following steps:

[0009] Step 1: Modify the single-polarization array radar by sparsely arranging orthogonal polarization array elements, reconstructing the array pattern, and obtaining the beam synthesis weights through adaptive beamforming technology.

[0010] Step 2: Using the point constraint method, joint polarization constraints are applied to the array. The effects of array cross-polarization are compensated and controlled by the modified orthogonal polarization array elements to obtain the array difference beam synthesis weight.

[0011] Step 3: By reconstructing the new sum and difference signal single-pulse angle measurement curve model, single-pulse angle measurement is achieved using the sum and difference signals received by the main polarization and cross-polarization channels of each array element.

[0012] The invention is further characterized in that,

[0013] The modification of the single-polarization array radar in step 1 specifically involves: setting the polarization array radar to include N uniformly arranged horizontally polarized antenna elements, and retaining N of them. H For horizontally polarized H-element arrays, N V Each array element is transformed into an orthogonal polarized V array element. The total received signal of the transformed polarized array is represented as x, and its covariance matrix is ​​Rx:

[0014] Rx=E[x·x H (1)

[0015] In equation (1), E represents the mean.

[0016] In step 1, the beamforming weights obtained through adaptive beamforming technology are specifically as follows: Taylor weights are used as the initial beamforming weights ω. qΣ Based on the minimum variance distortionless adaptive filtering criterion, the adaptive and beamforming combined weights ω are obtained. Σ :

[0017] ω ∑ =R x -1 ·ω q∑ (2).

[0018] Step 2 is as follows:

[0019] Step 2.1: The components of the H-polarized signal received by the array elements are: the main polarization channel component of the H-polarized array element and the cross-polarization channel component of the V-polarized array element; the gain of the array receiving the H-polarized signal is obtained as follows:

[0020]

[0021] In equation (3), F H (θ) is the set of radiation patterns of each array element receiving H-polarized signals, including the main polarization radiation pattern F of the H-polarized array elements. HH Cross-polarization pattern F of V-polarization array elements HV ;ω Δ Differential beamforming weights;

[0022] The components of the V-polarized signal received by the array elements are: the cross-polarization channel component of the H-polarized array elements and the main polarization channel component of the V-polarized array elements; the gain of the array receiving the V-polarized signal is obtained as follows:

[0023]

[0024] In equation (4), F V (θ) is the set of radiation patterns for each array element receiving V-polarized signals, including the cross-polarization radiation pattern F of the H-polarized array elements. VH The main polarization pattern F of the V-polarization array element VV ;

[0025] Step 2.2, the constraint conditions for calculating the difference beamforming weights are:

[0026]

[0027] In equation (5),

[0028]

[0029] In equation (6), θ0 is the spatial angle of the array beam pointing, θ c To select the spatial angle of the constraint point, K is the slope of the standard single-pulse angle measurement curve;

[0030] Step 2.3: The calculated difference beamforming weights are as follows:

[0031] ω Δ =Rx -1 ·C·(C H ·Rx -1 ·C) -1 ·f (7).

[0032] The single-pulse angle measurement result θ in step 3 is:

[0033]

[0034] In equation (8), Δ m The main polarization channel difference signal, Σ m Main polarization channel and signal, Δ c For the cross-polarization channel difference signal, Σ c For cross-polarization channels and signals.

[0035] The beneficial effects of this invention are:

[0036] 1) Broad application prospects. This invention targets the widely used single-polarization array radar, and at a lower cost, eliminates the monopulse angle measurement error caused by array element coupling and array cross-polarization, which can significantly improve the angle measurement performance of polarization array radar in practical applications.

[0037] 2) Stable and reliable performance. The single-pulse angle measurement method proposed in this invention abandons the conventional approach of suppressing cross-polarization as a source of angle measurement error. Instead, it uses low-cost array modification to fully utilize all the main polarization and cross-polarization information for joint constraint, avoiding residual cross-polarization error caused by insufficient cross-polarization suppression. The angle measurement result is not affected by the polarization of the incoming wave from the target, and the performance is stable. Attached Figure Description

[0038] Figure 1 This is a flowchart illustrating the array single-pulse angle measurement correction method based on orthogonal polarization sparse distribution of the present invention.

[0039] Figure 2 This is a schematic diagram of the array in the array single-pulse angle measurement correction method based on orthogonal polarization sparse distribution of the present invention;

[0040] Figure 3 shows the array element radiation patterns simulated on the HFSS platform based on the simulation results of the array single-pulse angle measurement correction method based on orthogonal polarization sparse distribution of the present invention; wherein, Figure 3(a) is the main polarization radiation pattern of 6 H array elements, Figure 3(b) is the cross polarization radiation pattern of 6 H array elements, Figure 3(c) is the main polarization radiation pattern of 2 V array elements, and Figure 3(d) is the cross polarization radiation pattern of 2 V array elements.

[0041] Figure 4 is a comparison of the angle measurement error of a single-polarization array and the simulation experiment using the array single-pulse angle measurement correction method based on orthogonal polarization sparse distribution of the present invention; wherein, Figure 4(a) is the root mean square error (RMSE) of the angle measurement result of the single-polarization array; Figure 4(b) is the root mean square error (RMSE) of the angle measurement result using the method of the present invention. Detailed Implementation

[0042] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0043] Example 1

[0044] This invention provides a method for array monopulse angle measurement correction based on orthogonal polarization sparse distribution. Addressing the non-ideal polarization factors in single-polarization array radar, such as element coupling and antenna cross-polarization, the method first modifies the single-polarization array by sparsely arranging a small number of orthogonal polarization elements and reconstructing the array radiation pattern. Adaptive beamforming technology is then used to obtain the sum-beam synthesis weights. Next, point constraints are applied to the array for joint polarization constraints. The modified orthogonal polarization elements compensate for and control the influence of array cross-polarization, yielding the array difference beam synthesis weights. Finally, a novel sum-difference signal monopulse angle measurement curve model is constructed, utilizing the sum and difference signals received by the main polarization and cross-polarization channels of each element to achieve accurate monopulse angle measurement.

[0045] Example 2

[0046] This invention provides a method for array monopulse angle measurement correction based on orthogonal polarization sparse distribution, such as... Figure 1 As shown, please follow these steps:

[0047] The first step is the modification and adaptive beamforming of the single-polarization array.

[0048] The following example uses a uniformly arranged linear array. Figure 2 This is a schematic diagram of the array of the present invention. The polarized array radar includes N horizontally polarized antenna elements arranged uniformly, wherein N... H Retained as horizontally polarized H-element, N V Each array element is transformed into an orthogonally polarized V array element. The total received signal of the transformed polarized array is denoted as x, and its covariance matrix is ​​Rx:

[0049] Rx=E[x·x H (1)

[0050] Taylor weights are used as initial values ​​and beam weights ω. qΣ Based on the minimum variance distortionless adaptive filtering criterion, the adaptive sum beam weights ω are obtained. Σ :

[0051] ω ∑ =R x -1 ·ω q∑ (2)

[0052] The second step involves joint polarization constraints and difference beamforming based on point constraints.

[0053] The spatial angle of the array beam pointing is denoted as θ0, and the spatial angle of the selected constraint point is denoted as θ. c (Generally, this is near the direction of the array's main beam, i.e., within the linear region of the standard monopulse angle measurement curve). The slope of the standard monopulse angle measurement curve is denoted as K, and the difference beam weight, calculated through constraints, is denoted as ω. Δ .

[0054] The components of the H-polarized signal received by the array elements are: the main polarization channel component of the H-polarized array elements and the cross-polarization channel component of the V-polarized array elements. The gain of the array in receiving the H-polarized signal is:

[0055]

[0056] F H (θ) is the set of radiation patterns of each array element receiving H-polarized signals, including the main polarization radiation pattern F of the H-polarized array elements. HH Cross-polarization pattern F of V-polarization array elements HV .

[0057] Similarly, the components of the V-polarized signal received by the array elements are: the cross-polarization channel component of the H-polarized array elements, and the main polarization channel component of the V-polarized array elements. The gain of the array in receiving the V-polarized signal is:

[0058]

[0059] F V (θ) is the set of radiation patterns for each array element receiving V-polarized signals, including the cross-polarization radiation pattern F of the H-polarized array elements. VH The main polarization pattern F of the V-polarization array element VV .

[0060] F HH F VH F VV F HV When array antennas leave the factory, they are fixed and measurable based on the array, including the coupling information between array elements.

[0061] The constraints for calculating the difference beam weights are:

[0062]

[0063] in,

[0064]

[0065] The calculated difference beam is:

[0066] ω Δ =Rx -1 ·C·(C H ·Rx -1 ·C) -1 ·f (7)

[0067] The third step is to reconstruct the single-pulse angle measurement model:

[0068] For the main polarization channel of the array, the received signal contains the main polarization component of the H / V polarization array elements, denoted as x. m For the cross-polarization channel of the array, the received signal contains the cross-polarization component of the H / V polarization array elements, denoted as x. c All of the above signal components are included in the received signal of the array. In the method of this invention, there is no need to distinguish between them to determine whether to utilize or suppress them. The beam weight ω from the first step is used... Σ The difference beam weights ω in the second step Δ The sum and difference signals (main polarization channel difference signal Δ) of the array received signal after filtering through the main / cross polarization channels are combined. m Main polarization channel and signal Σ m Cross-polarization channel difference signal Δ c Cross-polarization channels and signal Σc The single-pulse angle measurement result θ of the target signal is determined as follows:

[0069]

[0070] Example 3

[0071] Figure 3 shows the array element polarization patterns simulated on the HFSS platform; Figure 3(a) shows the main polarization pattern of 6 H elements, Figure 3(b) shows the cross-polarization pattern of 6 H elements, Figure 3(c) shows the main polarization pattern of 2 V elements, and Figure 3(d) shows the cross-polarization pattern of 2 V elements. The simulation results of this invention are based on the above data.

[0072] Figure 4 is a comparison of the angle measurement errors of the simulation experiment using this invention and a single-polarization array. The simulation experiment was conducted on a general-purpose computer, using the HFSS platform to simulate the array element radiation pattern data, and implemented using the Matlab simulation platform. The simulation parameters were set as follows: number of array elements N = 8, number of main polarization and horizontal polarization array elements N H =6, Number of orthogonal polarization elements N V =2, the array main beam spatial pointing is 45°, and the 3dB main lobe width is 15°. In the figure, the X-axis coordinate is the target signal spatial angle, and the Y-axis is the root mean square error of the angle measurement result. Figure 4(a) shows the root mean square error of the angle measurement result of the single-polarization array radar; Figure 4(b) shows the root mean square error of the angle measurement result using the method of the present invention. It can be seen that in Figure 4(a), due to the influence of cross-polarization, the error of the single-pulse angle measurement result is relatively large. In Figure 4(b), the method of the present invention can guarantee the accuracy of the angle measurement result within the spatial angle centered on the beam pointing angle. The angle measurement error within the constrained area is all below 0.005°.

Claims

1. A method for correcting the angle measurement of an array of single pulses based on orthogonal polarization sparse distribution, characterized in that, Includes the following steps: Step 1: Modify the single-polarization array radar by sparsely arranging orthogonal polarization elements, reconstructing the array pattern, and obtaining the beamforming weights through adaptive beamforming technology. Specifically, the modification of the single-polarization array radar involves setting the polarization array radar to include uniformly arranged... N A horizontally polarized antenna array element, retaining the following: N H For horizontally polarized H-element arrays, N V Each array element is transformed into an orthogonal polarized V array element. The total received signal of the transformed polarized array is expressed as follows: x Its covariance matrix is Rx : （1） In equation (1), E To find the mean; The beamforming weights obtained through adaptive beamforming technology are specifically: Taylor weights are used as the initial beamforming weights. ω qΣ Based on the minimum variance distortionless adaptive filtering criterion, adaptive and beamforming synthesis weights are obtained. ω Σ : （2） Step 2: Using point constraints, apply joint polarization constraints to the array. By modifying the orthogonally polarized array elements, compensate for and control the effects of array cross-polarization, obtaining the array difference beamforming weights; specifically: Step 2.1: The components of the H-polarized signal received by the array elements are: the main polarization channel component of the H-polarized array element and the cross-polarization channel component of the V-polarized array element; the gain of the array receiving the H-polarized signal is obtained as follows: （3） In equation (3), F H ( θ This is a set of radiation patterns for each array element receiving H-polarized signals, including the main polarization radiation pattern of the H-polarized array elements. F HH Cross-polarization pattern of V-polarization array elements F HV ; Differential beamforming weights; The components of the V-polarized signal received by the array elements are: the cross-polarization channel component of the H-polarized array elements and the main polarization channel component of the V-polarized array elements; the gain of the array receiving the V-polarized signal is obtained as follows: （4） In equation (4), F V ( θ This is a set of radiation patterns for each array element receiving V-polarized signals, including the cross-polarization radiation patterns of H-polarized array elements. F VH The main polarization pattern of the V-polarized array element F VV ; Step 2.2, the constraint conditions for calculating the difference beamforming weights are: （5） In equation (5), （6） In equation (6), θ 0 represents the spatial angle in which the array beam points. θ c To select the spatial angle of the constraint point, K The slope of the standard single-pulse angle measurement curve; Step 2.3: The calculated difference beamforming weights are as follows: （7） Step 3: Using the reconstructed novel sum-difference signal single-pulse angle measurement curve model, single-pulse angle measurement is achieved by utilizing the sum-difference signals received by the main polarization and cross-polarization channels of each array element; single-pulse angle measurement results. θ for: （8） In equation (8), Δ m The main polarization channel difference signal, Σ m Main polarization channel and signal, Δ c For the cross-polarization channel difference signal, Σ c For cross-polarization channels and signals.

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