A conformal array beamforming method with maximum SNR criterion

Abstract

A conformal array beamforming method based on the maximum SNR criterion comprises the following steps: (1) establishing a global coordinate system model for the conformal cylindrical array; (2) establishing a local coordinate system for each array element using Euler coordinate transformation; (3) calculating the element amplitude gain of each element based on the signal incident angle under the local coordinates and the element radiation pattern; (4) calculating the element activation threshold condition and determining whether the element is activated based on the element activation gain; (5) achieving the maximum SNR array output based on the element activation determination result. This invention can achieve the maximum SNR output of a conformal array of a certain size with incident signals at any angle, and the algorithm is simple. This invention can be applied to fields such as communication and radar.

Description

Technical Field

[0001] This invention relates to fields such as communications and radar, and specifically to a method for achieving maximum SNR output of received signals using a cylindrical conformal array. Background Technology

[0002] Conformal arrays are antenna arrays constructed by conformally attaching antenna elements to the surface of a carrier. They are widely used on spaceborne, airborne, and missile-borne platforms. While conformal arrays offer significant advantages and application potential, the anisotropy of the array elements and the blocking effect caused by the curvature of the carrier limit beamforming. Conventional beamforming and synthesis algorithms for planar phased arrays are no longer suitable for conformal phased arrays. In most conformal array beamforming algorithms, the most common solution is to convert the antenna's global coordinates to its local coordinates using Euler rotation to obtain the element factors before beamforming. However, this method involves all elements in the beamforming process, and elements with very low SNR actually reduce the overall SNR of the array output.

[0003] Therefore, to address the issue of maximizing the SNR of the conformal array output, it is necessary to model the received signal of the conformal array. Based on the unit amplitude gain of each array element, the array element activation threshold condition is calculated through an iterative method, and the participation of the array element in beamforming is determined to ensure that the array output meets the maximum SNR criterion. Summary of the Invention

[0004] The problem this invention aims to solve is: how to achieve the maximum SNR output of a cylindrical conformal array when a signal is incident on it from an arbitrary angle. The solution is a conformal array beamforming method based on the maximum SNR criterion, and its implementation steps are as follows:

[0005] (1) Establish a global coordinate system model for the cylindrical array; the surface of the cylindrical array has E equidistant rings, with a distance of M between adjacent rings. Each ring has D identical array elements at equal intervals, and the layout of the D array elements on different rings is completely identical. The radius of the cylinder is R, and the origin is located at the center of the circular section containing the midpoint of the generatrix of the cylindrical array. On the same ring, the angle between two adjacent array elements is α. The three-dimensional coordinates of the array element in the d-th row and e-th column can be represented as (p dex ,p dey ,p dez ), where d = 1,...,D, e = 1,...,E. The array receive signal matrix is:

[0006]

[0007] Where, τ de It is the delay of the received signal of the array element in row d and column e relative to the received signal of the origin. is the signal direction matrix with the incident angle of .

[0008] (2) Establish the local coordinate system for the element in the d-th row and e-th column. This local coordinate system is obtained by Euler rotation of the global coordinates, and the Euler rotation angles are α dez , α dex , α dey , specifically

[0009]

[0010] Calculate the incident angle of the element in the d-th row and e-th column in its local coordinate system through spatial geometric relationships as

[0011]

[0012]

[0013] (3) Each element of the cylindrical array has the same element pattern function. The incident angle information of the element in the d-th row and e-th column in its local coordinate system is According to calculate the element amplitude gain A de of this element. The element amplitude gain of the element in the d-th row and e-th column is

[0014]

[0015] (4) Sort all L = D × E elements in descending order according to the magnitude of the element amplitude gain A de , so A1 ≥ A2 ≥... ≥ A L , and the l-th element corresponds to the element amplitude gain A l , where l = 1,..., L. According to the arrangement order, judge whether to activate the l-th element, that is, whether to connect the signal received by the l-th element to the output of the entire array. The judgment steps are as follows:

[0016] First step, activate the first element with the largest element amplitude gain;

[0017] Second step, for the l-th element, calculate the judgment threshold A0, specifically

[0018]

[0019]

[0020] Third step, when the element amplitude gain A l of the l-th element < A0, do not enable this element, nor enable the L - l elements sorted later, let N = l - 1 and jump to step (5). When the element amplitude gain A lWhen it is ≥ A0, enable this array element. If l < L, then l = l + 1, and jump to the second step to continue judging the next array element. Otherwise, set N = L and jump to step (5).

[0021] (5) According to the N enabled units, obtain the output signal of the cylindrical array with the maximum SNR

[0022]

[0023] where, x l (t) is the received signal of the l-th array element sorted according to step (4), and is the shift-adding weight value of the received signal of this array element in the phased array antenna channel.

[0024] The beneficial effect of the present invention is that for any incident angle on a cylindrical conformal array of a certain scale, it can achieve the maximum SNR output of the array, and the algorithm is simple. The present invention can be applied to fields such as communication and radar. Description of the Drawings

[0025] Figure 1 is the structure diagram of the cylindrical conformal array;

[0026] Figure 2 is the flowchart of the conformal array beamforming method based on the maximum SNR criterion; Detailed Embodiment

[0027] First, establish a global coordinate system model of the conformal cylindrical array, obtain the signal incident angle in the local coordinate system through Euler rotation, and calculate the element amplitude gain of the array element through the element pattern. Next, calculate the threshold condition for enabling the array element, and finally achieve the maximum SNR output. The overall steps are as Figure 2 shown, and the specific implementation steps are as follows:

[0028] (1) Establish a global coordinate system model of the cylindrical array; there are E equally spaced circular rings on the surface of the cylindrical array, and the distance between adjacent two circular rings is M. There are D identical array elements equally spaced on each circular ring, and the layout of the D array elements on different circular rings is exactly the same. The radius of the cylinder is R, and the origin is located at the center of the circular cross-section where the midpoint of the generatrix of the cylindrical array is located. On the same circular ring, the angle between adjacent two array elements is α. The three-dimensional coordinates of the array element in the d-th row and e-th column can be expressed as (p dex , p dey , p dez ), where d = 1,..., D, e = 1,..., E. The array received signal matrix is

[0029]

[0030] where, τ de is the delay of the received signal of the array element in the d-th row and e-th column relative to the received signal at the coordinate origin, is the signal direction matrix with an incident angle of .

[0031] (2) Establish a local coordinate system for the element in the d-th row and e-th column. This local coordinate system is obtained through Euler rotation of the global coordinates, and the Euler rotation angles are α dez , α dex , α dey , specifically

[0032]

[0033] Calculate the incident angle in the local coordinate system of the element in the d-th row and e-th column through spatial geometric relationships as

[0034]

[0035]

[0036] (3) Each element of the cylindrical array has the same element pattern function. The incident angle information in the local coordinate system of the element in the d-th row and e-th column is According to calculate the element amplitude gain A de of this element. The element amplitude gain of the element in the d-th row and e-th column is

[0037]

[0038] (4) Sort all L = D × E elements in descending order according to the magnitude of the element amplitude gain A de , so A1 ≥ A2 ≥... ≥ A L , and the l-th element corresponds to the element amplitude gain A l , where l = 1,..., L. According to the arrangement order, judge whether to activate the l-th element, that is, whether to connect the signal received by the l-th element to the output of the entire array. The judgment steps are as follows:

[0039] First step, activate the 1st element with the largest element amplitude gain;

[0040] Second step, for the l-th element, calculate the judgment threshold A0, specifically

[0041]

[0042]

[0043] Third step, when the element amplitude gain A l of the l-th element < A0, do not enable this element, nor enable the L - l elements sorted later. Let N = l - 1 and jump to step (5). When the element amplitude gain A of the l-th elementl When ≥A0, enable this array element. If l < L, then l = l + 1, jump to the second step to continue judging the next array element, otherwise set N = L and jump to step (5).

[0044] (5) Obtain the output signal of the cylindrical array with the maximum SNR according to the N enabled units

[0045]

[0046] where x l (t) is the received signal of the l-th array element sorted according to step (4), is the shift and addition weighting value of the received signal of this array element in the phased array antenna channel.

[0047] The present invention can achieve the maximum SNR output of the array for any angle incident on a conformal array of a certain scale, and the algorithm is simple. The present invention can be applied to fields such as communication and radar.

Claims

1. A conformal array beamforming method based on the maximum SNR criterion, the implementation steps of which are: (1) Establish a global coordinate system model for the cylindrical array; there are E equidistant rings on the surface of the cylindrical array, with a distance of M between adjacent rings; each ring has D identical array elements at equal intervals, and the layout of the D array elements on different rings is exactly the same; the radius of the cylinder is R, and the origin is located at the center of the circular section where the midpoint of the generatrix of the cylindrical array is located; on the same ring, the angle between two adjacent array elements is α; the three-dimensional coordinates of the array element in the d-th row and e-th column can be represented as (p dex ,p dey ,p dez ), where d = 1,...,D, e = 1,...,E; the array receiving signal matrix is in, τ de It is the delay of the received signal of the array element in row d and column e relative to the received signal of the origin. The incident angle is The signal direction matrix; (2) Establish a local coordinate system for the array element in row d and column e; this local coordinate system is obtained by Euler rotation of the global coordinate system, with Euler rotation angles α and α' respectively. dez α dex α dey Specifically Using spatial geometric relationships, the incident angle in the local coordinate system of the element in row d and column e is calculated as follows: (3) Each element of the cylindrical array has the same element pattern function. The incident angle information of the element in the local coordinate system of the d-th row and e-th column is: according to Calculate the element amplitude gain A of this array element. de The element amplitude gain of the d-th row and e-th column array element is (4) All L = D × E array elements are adjusted according to the unit amplitude gain A. de If the values ​​are sorted from largest to smallest, then A1 ≥ A2 ≥ ... ≥ A L And the amplitude gain A of the unit corresponding to the l-th array element l Where l = 1, ..., L; according to the arrangement order, determine whether to turn on the l-th array element, that is, whether to connect the received signal of the l-th array element to the output of the entire array. The determination steps are as follows: The first step is to activate the first array element with the largest amplitude gain. The second step is to calculate the judgment threshold A0 for the l-th array element, specifically as follows: The third step is to increase the unit amplitude gain A of the l-th array element. l When A < A0, the array element is not enabled, nor are the L1 array elements ordered after it. Let N = l-1 and jump to step (5); when the unit amplitude gain A of the l-th array element is... l When A0 is greater than or equal to 0, the array element is activated. If l < L, then l = l + 1, jump to the second step to continue judging the next array element; otherwise, let N = L and jump to step (5). (5) Based on the N activated cells, obtain the cylindrical array output signal with the maximum SNR. Where, x l (t) is the signal received by the l-th array element after sorting according to step (4). This is the phase-shift weighting value of the signal received by this array element in the phased array antenna channel.

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