A method for reducing the radiation sidelobes of an array antenna

Abstract

This invention discloses a method for reducing the sidelobes of an array antenna. The method includes the following steps: acquiring the element array antenna structure, number of feed points, and operating frequency of the array antenna and inputting them into electromagnetic simulation software; determining the main lobe beamwidth of the array antenna under equal amplitude and phase excitation using simulation software; performing full-wave simulation on the array antenna to obtain the amplitude and phase of the electric and magnetic fields at the main lobe center point of the far-field radiation region of each array element in the radiation direction, as well as at points deviating from the main lobe center point by a certain degree; increasing the radiated power distribution in the main lobe direction of the array antenna to reduce sidelobes, and obtaining the excitation distribution when the radiation efficiency reaches its maximum under this power distribution, thus obtaining the excitation distribution for low sidelobe performance of the array. This invention transforms the problem of reducing antenna array sidelobes into a problem of increasing the power proportion in the main lobe radiation direction, thereby increasing the radiated energy in the main lobe direction and achieving the effect of reducing sidelobes.

Description

Technical Field

[0001] This invention relates to the field of communication technology, and more specifically to a method for reducing the radiated sidelobes of an array antenna. Background Technology

[0002] Traditional analytical methods for reducing sidelobes based on amplitude weighting (Chebyshev synthesis, Taylor synthesis, binomial method) are only applicable to equidistant antenna arrays with forward radiation. They lack greater versatility and speed, and are limited by amplitude adjustment. Currently, there is a lack of a more versatile and convenient method for reducing array antenna amplitude lobes that is not limited by antenna arrangement. This invention utilizes the maximum transmission efficiency method, increasing the radiated power at the edge of the main lobe, concentrating more power in the direction of the main lobe to reduce array sidelobes. Summary of the Invention

[0003] This invention addresses the shortcomings of existing technologies by providing a method for reducing the sidelobes of an array antenna that is more versatile and convenient, not limited by the form, arrangement, or radiation mode of the antenna, and has greater freedom and versatility.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] In a first aspect, embodiments of the present invention propose a method for reducing the radiation sidelobes of an array antenna, the method comprising the following steps:

[0006] S1, obtain the unit array antenna arrangement structure, number of feed points n, and operating frequency f0 of the array antenna;

[0007] S2, Using simulation software, add a field monitor at frequency f0 to obtain the main lobe beamwidth θ of the array antenna at different planes during the initial radiation pattern at frequency f0 (before reducing sidelobes). i ;

[0008] S3. Perform full-wave simulation on the array antenna to obtain the far-field main lobe center point O and the offset from the main lobe center point k for each array element. i Point P of degree i The amplitude and phase of the electric and magnetic fields at the location;

[0009] S4, assign points O and P i Weight function W p (r), combined with the radiation characteristics of the antenna array element, the excitation distribution when the maximum radiation efficiency is achieved under this power distribution is obtained by the maximum power transmission efficiency method, so as to increase the radiation energy in the main lobe direction.

[0010] Further, in step S2, if the array antenna is a one-dimensional array antenna structure, the main lobe beamwidth θ1 of the E-plane of the f0 radiation pattern is obtained; otherwise, if the array antenna is a non-one-dimensional array antenna, the main lobe beamwidths θ1-θ4 of the E-plane, H-plane, and two planes that form a 45° angle with the E-plane and H-plane are obtained.

[0011] Further, in step S3, if the array antenna is a one-dimensional array antenna structure, the values ​​of the two plane endpoints P1 and P2 on the E plane that are k degrees away from the main lobe center point O are obtained. If the array antenna is a non-one-dimensional array antenna, the values ​​of the eight plane endpoints P1-P8 on the four planes that are k degrees away from the main lobe center point O, the E plane, the H plane, and the planes that are at 45° angles to the E plane and the H plane are obtained.

[0012] Furthermore, in step S4, the process of determining the excitation distribution when the array antenna achieves maximum radiation efficiency under this power distribution using the maximum power transmission efficiency method includes the following sub-steps:

[0013] S41, for an array antenna consisting of m antenna elements, the electromagnetic power distribution radiated by the specified array antenna is given. The electromagnetic power in a specified area can be obtained by integrating the Poynting vector over the specified area. The transmission efficiency (PTE) of the entire antenna array is expressed as:

[0014]

[0015] Where S p The region is the integration region; E(r) represents the electric field matrix vector radiated in the far field region when each antenna element is excited; P represents the conjugate transpose of the magnetic field matrix vector radiated in the far field region when excited by the antenna; in Input power; W p (r) is a weighting parameter, a weighting function used to adjust the radiated power in a specific direction; u n The direction vector is specified in the direction; if all array elements are matched, equation (1) is simplified using the Ruili quotient expression as follows:

[0016]

[0017] in,

[0018] [a t [A] represents the array excitation distribution. p ] is one of the matrices in an m x m matrix, and the specific calculation formula is as follows:

[0019]

[0020] S42, add a proportional weighting function W p (r), combined with simulation data and formulas (3) and (4), matrix [A] is obtained by calculation;

[0021] S43, find the largest eigenvalue of matrix [A], and take the eigenvector corresponding to the largest eigenvalue of matrix [A] as the optimal excitation distribution under this power distribution.

[0022] Furthermore, the reduction method also includes:

[0023] Within the limits of antenna performance, by changing k i or W p The value of (r) is used to adjust the main lobe beamwidth; as k... i value or endpoint P i As the weight increases, the main lobe beamwidth widens and the sidelobes shrink, and vice versa.

[0024] Furthermore, the k i The value of k is: i =0.375θ i .

[0025] The beneficial effects of this invention are:

[0026] The design method for reducing the radiation sidelobes of an array antenna proposed in this invention transforms the problem of reducing antenna array sidelobes into the problem of increasing the power proportion in a specified main lobe radiation direction. Based on the radiation characteristics of the antenna array elements, the excitation distribution that achieves maximum transmission efficiency under this distribution is obtained by using the maximum power transmission theory, thereby increasing the radiation energy in the main lobe direction and thus achieving the effect of reducing sidelobes. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the design method for reducing the radiation sidelobes of an array antenna according to an embodiment of the present invention.

[0028] Figure 2 This is a schematic diagram of the electromagnetic power array antenna according to an embodiment of the present invention.

[0029] Figure 3 This is a schematic diagram of the electromagnetic field amplitude and phase points according to an embodiment of the present invention.

[0030] Figure 4 This is a schematic diagram of the antenna results according to an embodiment of the present invention.

[0031] Figure 5 This is a schematic diagram of the radiation direction of the E-plane under the same amplitude and phase excitation of an embodiment of the present invention.

[0032] Figure 6 This is a schematic diagram comparing the E-plane radiation structure of the low sidelobe excitation distribution and the same amplitude and phase excitation distribution according to an embodiment of the present invention. Detailed Implementation

[0033] The invention will now be described in further detail with reference to the accompanying drawings.

[0034] It should be noted that the terms such as "upper", "lower", "left", "right", "front", and "back" used in the invention are only for clarity of description and are not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0035] Example 1

[0036] Figure 1 This is a schematic diagram of the design method for reducing the radiation sidelobes of an array antenna according to an embodiment of the present invention. Figure 2 This is a schematic diagram of the electromagnetic power array antenna according to an embodiment of the present invention. Figure 3 This is a schematic diagram of the electromagnetic field amplitude and phase points according to an embodiment of the present invention. Figure 4 This is a schematic diagram of the antenna results according to an embodiment of the present invention. This embodiment proposes a method for reducing the radiation sidelobes of an array antenna, which includes the following steps:

[0037] S1, obtain the unit array antenna arrangement structure, the number of feed points n, and the operating frequency f0 of the array antenna.

[0038] S2, Using simulation software, add a field monitor at frequency f0 to obtain the main lobe beamwidth θ of the array antenna at different planes during the initial radiation pattern at frequency f0 (before reducing sidelobes). i .

[0039] S3. Perform full-wave simulation on the array antenna to obtain the far-field main lobe center point O and the offset from the main lobe center point k for each array element. i Point P of degree i The amplitude and phase of the electric and magnetic fields at the location.

[0040] S4, assign points O and P i Weight function W p (r), combined with the radiation characteristics of the antenna array element, the excitation distribution when the maximum radiation efficiency is achieved under this power distribution is obtained by the maximum power transmission efficiency method, so as to increase the radiation energy in the main lobe direction.

[0041] I. Obtaining Antenna Array Related Data

[0042] Obtain the unit array antenna structure, number of feed points, and operating frequency of the array antenna, and input them into the electromagnetic simulation software.

[0043] For example, this example provides a method for reducing the sidelobes of an array antenna, and provides a seven-element array antenna structure such as Figure 4 As shown, the antenna elements of this array are as follows: Figure 3 As shown in (a), the resonant frequency is 5.31 GHz. To verify that the method provided by this invention is applicable to non-equally spaced arrays, the seven-element array is a non-equally spaced array. The specific dimensions of the above structure are: (x = 16.8 mm, y = 12.7 mm, s = 7.02 mm, subw = 40 mm, subl = 255 mm, s1 = 30 mm, h = 0.8 mm, s2 = 35 mm, s3 = 40 mm). The substrate uses F4B material (dielectric constant is 2.55, loss tangent is 0.0027).

[0044] II. Determining the main lobe beamwidth

[0045] The electromagnetic power of the preprocessed array antenna is calculated using simulation software based on the antenna structure, number of feed points, and operating frequency collected in step S1.

[0046] Add a far-field monitor at this electromagnetic power level, input an excitation distribution with the same amplitude and phase, and obtain the main lobe beamwidth θ of the radiation pattern at this electromagnetic power level.

[0047] For example, in this embodiment, the array antenna is modeled in CST electromagnetic simulation software, and a 5.31 GHz far-field monitor is added. Simulation is performed using equal-amplitude, equal-phase excitation to obtain the E-plane radiation pattern, as shown below. Figure 4 As shown, the main lobe width is obtained as θ = 28°.

[0048] III. Full-wave simulation

[0049] Full-wave simulation of the array antenna was performed to obtain the plane endpoint P of the main lobe beamwidth at the main lobe center point O of each array element in the radiation direction, with a distance of k = 0.375 degrees from point O. i Electromagnetic amplitude and phase at that location.

[0050] Preferably, when the array antenna is a one-dimensional array antenna structure, it is necessary to obtain two endpoint values ​​in the one-dimensional direction of the main lobe (YOZ plane). If the array antenna is a two-dimensional array antenna, it is necessary to obtain four endpoint values ​​in two orthogonal directions (XOZ and YOZ planes).

[0051] For example, when performing full-wave simulation of the array antenna, since the array is a one-dimensional array, it is only necessary to obtain the amplitude and phase of the electric field at the center point of the main lobe of the E plane and at a distance of k = 0.375θ = ±10.5° from the center point of the main lobe (magnetic field amplitude = electric field amplitude / 377, the magnetic field and electric field are in phase), as shown in Table 1.

[0052] Table 1

[0053]

[0054] IV. Excitation Distribution for Obtaining Low Sidelobe Performance of the Array

[0055] Step S4, the process of determining the excitation distribution that achieves maximum transmission efficiency under this power distribution using the maximum power transmission theory, includes the following sub-steps:

[0056] S41, for an array antenna consisting of m antenna elements, the electromagnetic power distribution radiated by the specified array antenna is given. The electromagnetic power in a specified area can be obtained by integrating the Poynting vector over the specified area. The transmission efficiency (PTE) of the entire antenna array is expressed as:

[0057]

[0058] Where S p The region is the integration region; E(r) represents the electric field matrix vector radiated in the far field region when each antenna element is excited; P represents the conjugate transpose of the magnetic field matrix vector radiated in the far field region when excited by the antenna; in Input power; W p (r) is a weighting parameter, a weighting function used to adjust the radiated power in a specific direction; u n The direction vector is specified in the direction; if all array elements are matched, equation (1) is simplified using the Ruili quotient expression as follows:

[0059]

[0060] in,

[0061] [a t [A] represents the array excitation distribution. p ] is one of the matrices in an m x m matrix, and the specific calculation formula is as follows:

[0062]

[0063] S42, add a proportional weighting function W p (r), combined with simulation data, and formulas (3) and (4) are used to calculate matrix [A].

[0064] S43, find the largest eigenvalue of matrix [A], and take the eigenvector corresponding to the largest eigenvalue of matrix [A] as the optimal excitation distribution under this power distribution.

[0065] Preferably, within the limits of antenna performance, by changing k or W p The value of (r) is used to adjust the main lobe beamwidth, depending on the value of k or the endpoint P. i As the weighting increases, the main lobe beamwidth widens and the side lobes shrink, and vice versa.

[0066] Where k = 0.375θ.

[0067] For example, assigning equal weights Wp(r) of 1:1:1 to the three-point radiated power, the matrix [A] is obtained from the formula. The eigenvector corresponding to the largest eigenvalue of [A] is then calculated and normalized to the excitation distribution of each port of the antenna array, as shown in Table 2. The excitation is fed into the array for verification, and the results are as follows. Figure 5 As shown, compared with the same amplitude and phase excitation, the side lobes are significantly reduced, which is in line with the expected effect of the present invention.

[0068] Table 2

[0069] port excitation 1 0.13∠-13 2 0.34∠-6 3 0.48∠-3 4 0.50∠0 5 0.48∠0 6 0.35∠1 7 0.14∠3

[0070] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A method for reducing the radiated sidelobes of an array antenna, characterized in that, The reduction method includes the following steps: S1, obtain the unit array antenna arrangement structure, number of feed points n, and operating frequency f0 of the array antenna; S2, by adding a field monitor at frequency f0 using simulation software, and inputting an excitation distribution with the same amplitude and phase, the beamwidth θ of the main lobe in different planes of the radiation pattern at frequency f0 of the array antenna is obtained. i ; S3. Perform a full-wave simulation of the array antenna to obtain the far-field main lobe center point O and the offset from the main lobe center point k for each array element in the radiation direction. i The main lobe beamwidth at the midplane endpoint P i The amplitude and phase of the electric and magnetic fields at point k; i The value of k is: i =0.375θ i When the array antenna is a one-dimensional array antenna structure, the two endpoint values ​​of the YOZ plane in the one-dimensional direction of the main lobe are obtained. If the array antenna is a two-dimensional array antenna, the four endpoint values ​​of the XOZ plane and YOZ plane in the two orthogonal directions are obtained. S4, assign points O and P i Weight function W p (r), combining the radiation characteristics of the antenna array element, the excitation distribution when the maximum radiation efficiency is achieved under this power distribution is obtained by the maximum power transmission efficiency method, so as to increase the radiation energy in the main lobe direction. Within the limits of antenna performance, by changing k i or W p The value of (r) is used to adjust the main lobe beamwidth; as k... i value or endpoint P i As the weight increases, the main lobe beamwidth widens and the sidelobes shrink, and vice versa.

2. The method for reducing radiation sidelobes of an array antenna according to claim 1, characterized in that, In step S2, if the array antenna is a one-dimensional array antenna structure, the main lobe beamwidth θ1 of the E-plane of the f0 radiation pattern is obtained; otherwise, if the array antenna is a non-one-dimensional array antenna, the main lobe beamwidths θ1-θ4 of the E-plane, H-plane, and two planes that form a 45° angle with the E-plane and H-plane are obtained.

3. The method for reducing radiation sidelobes of an array antenna according to claim 1, characterized in that, Step S4, the process of determining the excitation distribution when the array antenna achieves maximum radiation efficiency under this power distribution using the maximum power transmission efficiency method, includes the following sub-steps: S41, for an array antenna consisting of m antenna elements, the electromagnetic power distribution radiated by the specified array antenna is given. The electromagnetic power in a specified area can be obtained by integrating the Poynting vector over the specified area. The transmission efficiency (PTE) of the entire antenna array is expressed as: Where S p The region is the integration region; E(r) represents the electric field matrix vector radiated in the far field region when each antenna element is excited; P represents the conjugate transpose of the magnetic field matrix vector radiated in the far field region when excited by the antenna; in Input power; W p (r) is a weighting parameter, a weighting function used to adjust the radiated power in a specific direction; u n The direction vector is specified in the direction; if all array elements are matched, equation (1) is simplified using the Ruili quotient expression as follows: in, [a t [A] represents the array excitation distribution. p ] is one of the matrices in an m x m matrix, and the specific calculation formula is as follows: S42, add a proportional weighting function W p (r), combined with simulation data and formulas (3) and (4), matrix [A] is obtained by calculation; S43, find the largest eigenvalue of matrix [A], and take the eigenvector corresponding to the largest eigenvalue of matrix [A] as the optimal excitation distribution under this power distribution.

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