Low sidelobe antenna based on orthogonal rotating cross composite array

Abstract

This invention relates to a low-sidelobe antenna based on an orthogonal rotating cross-shaped composite array, comprising a basic L-shaped array and a rotating L-shaped array. The basic L-shaped array is composed of multiple antenna elements evenly spaced along the negative x-axis and negative y-axis, with the antenna element located at the intersection of the x-axis and y-axis designated as the center element. The rotating L-shaped array is formed by rotating the basic L-shaped array counterclockwise by 135° around the center element. The basic L-shaped array and the rotating L-shaped array are coplanarly spliced ​​together, with their center elements coinciding, forming a low-sidelobe antenna based on an orthogonal rotating cross-shaped composite array. The orthogonal rotating composite array architecture proposed in this invention breaks the strict symmetry of a single array by splicing two cross-shaped arrays at a specific angle, thereby achieving effective sidelobe suppression.

Description

Technical Field

[0001] This invention belongs to the field of satellite microwave ocean remote sensing, and relates to a low sidelobe antenna array structure that optimizes the radiation pattern through a special geometric configuration, which is suitable for satellite systems equipped with radiometers to carry out sea surface brightness temperature detection and inversion. Background Technology

[0002] In fields such as satellite microwave ocean remote sensing, the radiation pattern characteristics of an antenna array directly determine the system's detection sensitivity, anti-interference capability, and imaging resolution. Traditional cross-shaped antenna arrays, with their advantages of symmetrical structure and simple beam control, are widely used in microwave remote sensing, phased array radar, and satellite communications. However, with the ever-increasing performance requirements of modern wireless systems, this classic architecture has revealed a series of inherent defects, severely restricting its application in high-end scenarios.

[0003] The most prominent problem is high sidelobes. Due to the strict periodic symmetry of the cross-shaped array, its radiation pattern exhibits significant sidelobe structures along the main axes (x-axis and y-axis). Measured data shows that, under uniform feeding conditions, the first sidelobe level of a traditional cross-shaped array is generally higher than -15 dB (e.g., a typical 8-element cross-shaped array has sidelobes reaching -12.3 dB). These high sidelobes not only cause energy leakage and reduce main lobe gain, but also introduce multipath interference and noise, leading to a sharp increase in bit error rate in dense signal environments. In radar applications, high sidelobes can trigger false target detection, and in severe cases, even mask genuine weak signals.

[0004] In summary, how to achieve pattern sidelobe suppression while maintaining the simplicity and low cost of the array structure remains a long-standing technical bottleneck in this field. Summary of the Invention

[0005] The technical problem solved by this invention is to overcome the shortcomings of the prior art and propose a low sidelobe antenna based on an orthogonal rotating cross-shaped composite array.

[0006] The solution of the present invention is:

[0007] A low sidelobe antenna based on an orthogonal rotating cross-shaped composite array includes: a basic L-shaped array and a rotating L-shaped array;

[0008] The basic L-shaped array is composed of multiple antenna elements distributed at equal intervals along the negative half-axis of the x-axis and the negative half-axis of the y-axis, and the antenna element located at the intersection of the x-axis and the y-axis is denoted as the center element;

[0009] The rotating L-shaped array is formed by rotating a basic L-shaped array counterclockwise by 135° around the central unit;

[0010] The basic L-shaped array and the rotating L-shaped array are spliced ​​together in a coplanar manner, with their central units overlapping, forming a low sidelobe antenna based on an orthogonal rotating cross-shaped composite array.

[0011] Preferably, in the basic L-shaped array, excluding the central element, the number of antenna elements on both the negative half-axis of the x-axis and the negative half-axis of the y-axis is greater than or equal to 2.

[0012] Preferably, the spacing between adjacent antenna elements on the negative half-axis of the x-axis or the negative half-axis of the y-axis is 0.5λ, where λ is the wavelength corresponding to the center frequency of the antenna.

[0013] Preferably, the coordinates (x, y) of the k-th antenna element in the rotated L-shaped array k ,y k )satisfy

[0014] (x k ,y k )=R(135°)·(x i ,y j ) T

[0015] (x i ,y j ) represents the coordinates of the k-th antenna element in the basic L-shaped array.

[0016] Preferred,

[0017] Preferably, the UV plane of the low sidelobe antenna based on the orthogonal rotating cross-shaped composite array is zero-padded to obtain a square-covered UV plane.

[0018] Preferably, the low sidelobe antenna has both orthogonal symmetry and rotational symmetry.

[0019] The advantages of this invention compared to the prior art are:

[0020] 1. Significantly reduces sidelobes:

[0021] Traditional cross-shaped antenna arrays, due to their strict periodic symmetry, generate high sidelobe levels along the main axis, leading to energy leakage, multipath interference, and noise, severely impacting system performance. The orthogonal rotating composite array architecture proposed in this invention breaks the strict symmetry of a single array by splicing two L-shaped arrays at a specific angle (e.g., 135° or other optimized angles), thus achieving effective sidelobe suppression. The orthogonal rotating splicing design makes the baseline distribution more uniform, avoiding strong periodic resampling in a single direction, resulting in a smoother radiation pattern in the Fourier domain and effectively reducing sidelobe peaks.

[0022] 2. Efficient spatial sampling:

[0023] The cross-shaped layout of this invention, through careful design of antenna spacing and distribution, enables efficient spatial sampling with a limited number of antennas, meeting the application needs of microwave remote sensing, wireless communication, radio astronomy observation and other fields.

[0024] 3. Easy to implement and maintain:

[0025] The regularity and symmetry of the cross-shaped layout of this invention make the installation, debugging and maintenance of the antenna array more convenient, reducing the complexity and cost of system deployment.

[0026] 4. Optimized UV planar coverage:

[0027] The baseline pairs generated by the antenna array of this invention have good distribution characteristics in the UV plane. After zero-padding, they can be further optimized into square coverage, which facilitates subsequent Fourier transform and imaging processing.

[0028] 5. This invention can make up for the shortcomings of existing integrated aperture radiometers in orbit and under development, and can serve as a more optimized solution for future integrated aperture radiometers to carry out environmental and target detection, thereby enhancing my country's voice in the field of microwave radiation remote sensing. Attached Figure Description

[0029] Figure 1 Basic L-shaped array layout diagram;

[0030] Figure 2 The UV-plane coverage map generated from the basic L-shaped antenna array;

[0031] Figure 3 The original antenna array layout is shown with a 135-degree rotation.

[0032] Figure 4 This is the UV-plane coverage diagram of the spliced ​​antenna array. Detailed Implementation

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

[0034] This invention proposes an innovative orthogonal rotating cross-shaped composite array, which achieves sidelobe suppression through the following design:

[0035] (1) Basic L-shaped array: This consists of N antenna elements distributed along the negative x-axis and N antenna elements distributed along the negative y-axis, forming the first sub-array. The antenna element at the intersection of the negative x-axis and the negative y-axis is called the center element. For example... Figure 1 As shown. By Figure 1 The UV-plane coverage map generated by the antenna array is as follows Figure 2 As shown.

[0036] Number of elements and spacing: The number of antennas per arm N ≥ 2, and based on experience, N = 4 is preferred. The spacing between elements in a single arm is 0.5λ (λ is the wavelength corresponding to the center frequency of the antenna system). The total number of antenna elements is 2N+1. The negative half-axis of the x-axis is called one arm, and the negative half-axis of the y-axis is called one arm.

[0037] (2) Rotating L-shaped array: Rotate another L-shaped array with the same structure clockwise by 135° to form a second sub-array.

[0038] Transform the base array coordinates using a rotation matrix R (135°):

[0039]

[0040] (x k ,y k )=R(135°)·(x i ,y j ) T

[0041] (x k ,y k Let (x) be the coordinates of the k-th antenna element in the rotated L-shaped array. i ,y j ) represents the coordinates of the k-th antenna element in the basic L-shaped array.

[0042] (3) Composite splicing structure: Two subarrays are integrated coplanarly, sharing a central unit, and the overall layout combines orthogonal symmetry and rotational symmetry. For example... Figure 3 As shown.

[0043] The baseline pairs generated by the antenna array of this invention have good distribution characteristics in the UV plane, such as... Figure 4 As shown, after zero-padding, it can be further optimized into a square coverage, which facilitates subsequent Fourier transform and imaging processing.

[0044] The orthogonal rotation composite array architecture proposed in this invention breaks the strict symmetry of a single array by splicing two L-shaped arrays at a specific angle (such as 135° or other optimized angles), thereby achieving effective suppression of sidelobes. The orthogonal rotation splicing design makes the baseline distribution more uniform, avoids strong periodic resampling in a single direction, and thus forms a smoother radiation pattern in the Fourier domain, effectively reducing sidelobe peaks.

[0045] The parts of this invention not described in detail are common knowledge to those skilled in the art.

Claims

1. A low sidelobe antenna based on a crossed array of orthogonal rotations, characterized in that, include: Basic L-shaped array, rotated L-shaped array; The basic L-shaped array is composed of multiple antenna elements distributed at equal intervals along the negative half-axis of the x-axis and the negative half-axis of the y-axis, and the antenna element located at the intersection of the x-axis and the y-axis is denoted as the center element; The rotating L-shaped array is formed by rotating a basic L-shaped array counterclockwise by 135° around the central unit; The basic L-shaped array and the rotating L-shaped array are spliced ​​together in a coplanar manner, with their central units overlapping, forming a low sidelobe antenna based on an orthogonal rotating cross-shaped composite array.

2. The low sidelobe antenna based on the orthogonal rotating cross composite array according to claim 1, characterized in that, In the basic L-shaped array, excluding the central element, the number of antenna elements on both the negative x-axis and the negative y-axis is greater than or equal to 2.

3. The low sidelobe antenna based on the orthogonal rotating cross composite array according to claim 1, characterized in that, The spacing between adjacent antenna elements on the negative x-axis or negative y-axis is 0.5λ, where λ is the wavelength corresponding to the antenna center frequency.

4. The low sidelobe antenna based on the orthogonal rotating cross composite array according to claim 1, characterized in that, The coordinates (x k ,y k ) of the kth antenna element in the rotating L-shaped array satisfy (x k ,y k ) = R(90°) · (x i ,y j ) T (x i ,y j ) are the coordinates of the kth antenna element in the base L-shaped array.

5. A low sidelobe antenna based on an orthogonal rotating cross-shaped composite array according to claim 1, characterized in that, 6. The low sidelobe antenna based on the orthogonal rotating cross composite array according to claim 1, characterized in that, Zero-padding is performed on the UV plane of a low sidelobe antenna based on an orthogonal rotating cross-shaped composite array to obtain a square-covered UV plane.

7. A low sidelobe antenna based on an orthogonal rotating cross-shaped composite array according to claim 1, characterized in that, The low sidelobe antenna possesses both orthogonal symmetry and rotational symmetry.

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