A cosecant square beam antenna array for long-distance communication and its optimization method

Abstract

The present invention discloses a cosecant square beam antenna array for long-distance communication and an optimization method thereof, wherein the cosecant square beam antenna array for long-distance communication comprises an FR4 dielectric substrate and a plurality of U-shaped slot microstrip patch antenna units, wherein the plurality of U-shaped slot microstrip patch antenna units are flatly printed on the FR4 dielectric substrate, the plurality of U-shaped slot microstrip patch antenna units are evenly spaced, the FR4 dielectric substrate is arranged in a rectangular shape, the cosecant square beam shape is realized, the center of the U-shaped slot microstrip patch antenna unit is connected to an SMA head, and is connected to a feed network; the optimization method comprises antenna array design, cosecant square beam formation, designing a feed network according to the calculated optimized excitation distribution ODE, and performing microwave darkroom far-field physical testing. The present invention ensures the directivity and stability of signal transmission, effectively reduces the sidelobe level, reduces unnecessary signal interference, and improves the anti-interference capability, integration and flexibility of the antenna array.

Description

Technical Field

[0001] The present invention relates to the field of communication and information engineering, and in particular to a cosecant square beam antenna array for long-distance communication and an optimization method thereof. Background Art

[0002] In communication systems, traditional fan-beam antenna arrays are widely used due to their wide beam coverage and simple structure. However, with the continuous development of communication technology, people have higher and higher requirements for the quality of long-distance communication. Traditional fan-beam antenna arrays have gradually exposed the problem that the signal strength decreases significantly with increasing distance. This problem limits its application in long-distance communication, especially in scenarios that require stable and efficient signal transmission.

[0003] In addition, although the existing cosecant square pattern antenna arrays can provide more stable signal transmission, most of them have problems such as large size, large number of components, and high cost, which limits their application in space-constrained or cost-sensitive scenarios. Although some researchers have tried to reduce the size of antenna arrays by reducing the spacing between components or optimizing the array structure, this often leads to increased sidelobe levels, causing unnecessary interference to the communication system. Summary of the invention

[0004] Purpose of the invention: The purpose of the present invention is to provide a cosecant square beam antenna array for long-distance communication and an optimization method thereof.

[0005] Technical solution: The cosecant square beam antenna array for long-distance communication described in the present invention includes an FR4 dielectric substrate and a plurality of U-slot microstrip patch antenna units. The plurality of U-slot microstrip patch antenna units are flatly printed on the FR4 dielectric substrate. The plurality of U-slot microstrip patch antenna units are evenly spaced. The FR4 dielectric substrate is arranged in a rectangular shape to achieve a cosecant square beam shape. The center of the U-slot microstrip patch antenna unit is connected to an SMA head and is connected to a feeding network. The FR4 dielectric substrate is 3 mm thick, has a relative dielectric constant of 4.35, and a loss tangent of 0.025. The number of the U-slot microstrip patch antenna units is 18, which are symmetrically distributed on both sides of the center point.

[0006] Furthermore, the U-shaped slot microstrip patch antenna unit adopts a copper patch with a length of 、 Width , the interior is a U-shaped slot, the length of the slot is , width , the slot spacing is , the distance between the edge of the antenna unit and the U-shaped slot is , the distance between the feed point and the U-shaped slot is .

[0007] Furthermore, the distance between the U-slot microstrip patch antenna units is 0.35λ, where λ is the wavelength.

[0008] The cosecant square beam optimization method for long-distance communication described in the present invention is implemented by using the cosecant square beam antenna array for long-distance communication, and is characterized in that it includes the following steps:

[0009] S1: Antenna array design, including antenna element selection and array construction, determination of test point distribution and array tilt angle, and array prototype production;

[0010] S2: Cosecant square beamforming, including constructing weighting coefficients and weighting matrices and calculating the excitation distribution ODE of array elements;

[0011] S3: Design the feeding network based on the calculated optimized excitation distribution ODE;

[0012] S4: Conduct far-field physical tests in a microwave darkroom and compare the test results with the simulation results.

[0013] Furthermore, the step S1 distributes the test points on the spherical surface of the array far field area and sets the array tilt angle is 45°.

[0014] Furthermore, the weighted coefficient calculation formula constructed in step S2 is:

[0015] ,

[0016] in, Indicates p The weighting coefficient of the test points, Indicates q The weighting coefficient of each test point; Represents the horizontal plane and the transmitting antenna array to the test point p The angle between the directions; Represents the horizontal plane and the transmitting antenna array to the test point q The angle between the directions, m represents the dimension of the weighting matrix, represents the beam start angle of the cosecant squared beam area; Represents the beam coverage angle.

[0017] Furthermore, the excitation distribution ODE of the array elements in step S2 is expressed as:

[0018] ,

[0019] in, represents the excitation amplitude of each unit, represents the electric field distribution, H represents the conjugate transposed matrix, Wrepresents the weighting coefficient of the target radiation pattern, A represents the intermediate connection matrix.

[0020] Furthermore, the step S4 microwave darkroom far-field physical test includes placing the manufactured antenna array prototype at a suitable position in the microwave darkroom; using professional testing equipment to measure the radiation characteristics of the antenna array in the far field, and the measurement parameters include radiation pattern and gain.

[0021] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: the present invention adopts the maximum power transmission efficiency method, optimizes the beam coverage by adjusting the weight coefficient, and ensures the directionality and stability of signal transmission; uses the sidelobe suppression technology to introduce a smaller radiation field weight in the area outside the main beam, effectively reduces the sidelobe level, reduces unnecessary signal interference, and improves the anti-interference ability of the antenna array; by controlling the element spacing of the antenna array, while ensuring the antenna performance, the physical size of the antenna array is greatly reduced, the antenna array is miniaturized, and the antenna integration and flexibility are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the structure of the cosecant square beam antenna array;

[0023] Figure 2 It is a schematic diagram of the structure of a U-shaped slot microstrip patch antenna unit;

[0024] Figure 3 This is a physical picture of the far-field test in the anechoic chamber;

[0025] Figure 4 is the reflection coefficient diagram of the linear antenna array;

[0026] Figure 5 For the antenna array yz Normalized radiation pattern at 5.3 GHz on a plane. DETAILED DESCRIPTION

[0027] The technical solution of the present invention is further described below in conjunction with the accompanying drawings.

[0028] like Figure 1As shown, the cosecant square beam antenna array for long-distance communication described in the present invention includes an FR4 dielectric substrate and a plurality of U-groove microstrip patch antenna units, wherein the plurality of U-groove microstrip patch antenna units are flatly printed on the FR4 dielectric substrate, the plurality of U-groove microstrip patch antenna units are evenly spaced, and the FR4 dielectric substrate is arranged in a rectangular shape to realize a cosecant square beam shape, the center of the U-groove microstrip patch antenna unit is connected to an SMA head and is connected to a feeding network, the FR4 dielectric substrate is 3 mm thick, the relative dielectric constant is 4.35, the loss tangent is 0.025, and the number of the U-groove microstrip patch antenna units is 18, which are symmetrically distributed on both sides of the center point, as shown in FIG. Figure 2 As shown, the U-shaped slot microstrip patch antenna unit adopts a copper patch with a length of 、 Width , the interior is a U-shaped slot, the length of the slot is , width , the slot spacing is , the distance between the edge of the antenna unit and the U-shaped slot is , the distance between the feed point and the U-shaped slot is The distance between the U-slot microstrip patch antenna units is 0.35λ, where λ is the wavelength.

[0029] A compact 18-element linear microstrip antenna array based on the extended maximum power transfer efficiency (EMMPTE) method is used to achieve a cosecant square beam shape. The cosecant square beam optimization method for long-distance communication of the present invention comprises the following steps:

[0030] S1: Antenna Array Design

[0031] S11: Antenna element selection and array construction

[0032] A U-slot microstrip patch antenna with an operating frequency of 5.3 GHz is selected as the array element. This type of antenna has the characteristics of being suitable for building linear arrays and having good performance at the target frequency.

[0033] The antenna is printed on a specific FR4 substrate with a thickness of 3 mm, a relative dielectric constant of 4.35, and a loss tangent of 0.025. A linear antenna array with 18 elements evenly spaced is constructed on this substrate.

[0034] When designing the array, the EMMPTE method is used to fully consider the mutual coupling effect between elements. In this way, the element spacing is reduced from the conventional value to 0.35λ (λ is the wavelength), thereby realizing the miniaturization of the antenna array. Compared with the traditional design method, this design considering mutual coupling can break through the conventional spacing limitation and effectively reduce the overall size of the array.

[0035] S12: Determine the distribution of test points and the tilt angle of the array

[0036] Use commercial simulation software to obtain the electric field distribution matrix. In this process, the distribution of test points is crucial. Distributing the test points on the spherical surface of the array far field area can more comprehensively reflect the radiation characteristics of the antenna array in the far field.

[0037] Set the array tilt angle This angle is set to better align the cosecant square beam shape. By adjusting the tilt angle of the array, the radiation pattern of the antenna array can be optimized to better match the desired cosecant square beam shape, thereby improving the overall performance of the antenna array.

[0038] S13: Prototype the array

[0039] According to the previously optimized size and designed feed network, an 18-element linear microstrip antenna array prototype is produced. During the production process, it is necessary to strictly follow the design requirements for processing and manufacturing to ensure that the size, position and feed connection of each array element meet the design standards.

[0040] The completed array prototype is shown in Figure 1 As shown, the actual structure of the antenna array prototype and the layout of the feeding network are demonstrated.

[0041] S2: Cosecant Squared Beamforming

[0042] S21: Construct weighting coefficients and weighting matrices

[0043] In the antenna array design, in order to achieve sidelobe suppression and prevent signal degradation at test points at a longer distance, we introduced weighting coefficients. These coefficients are used to adjust the radiation signal strength of each test point, that is, to allocate stronger radiation signals to test points at a longer distance and weaker divergent signals to test points at a closer distance, so that the signal strength received at the test points is consistent.

[0044] The weighting coefficient calculation formula is as follows, which is used for the beamforming area and the sidelobe suppression area respectively:

[0045] ,

[0046] in, Indicates p The weighting coefficient of the test points, Indicates q The weighting coefficient of each test point; Represents the horizontal plane and the transmitting antenna array to the test point p The angle between the directions; Represents the horizontal plane and the transmitting antenna array to the test point q The angle between the directions, m represents the dimension of the weighting matrix, represents the beam start angle of the cosecant squared beam area; Represents the beam coverage angle.

[0047] In the beamforming region, the weighting coefficients are selected according to the cosecant square function. The basis for this selection is that the cosecant square function can accurately describe the characteristics of maintaining constant signal strength at different angles, thereby achieving a beam shape that meets the requirements.

[0048] For the sidelobe suppression area, a smaller weight is given outside the area. In this way, the radiation power in the sidelobe area can be effectively reduced, thereby achieving the goal of low sidelobe level. This method of setting different weighting coefficients for different areas can effectively suppress the sidelobe level while achieving the cosecant square beam shape, thereby improving the performance of the antenna array. Figure 5 The antenna array is shown in yz Normalized radiation pattern at 5.3 GHz on a plane.

[0049] By designing the elements in the weighting matrix, we can effectively control the radiation pattern to approach an ideal cosecant square beam shape. This beam shape is very effective in radar and communication systems, providing a wide main lobe and low side lobes.

[0050] S22: Compute the excitation distribution ODE of the array elements

[0051] In order to obtain the optimized excitation distribution, we use the weighted matrix and the electric field distribution matrix. By establishing the mathematical relationship between the two (as shown below), we can calculate the excitation distribution ODE with the help of the quadratic programming method,

[0052] The analytical form of ODE is:

[0053] ,

[0054] in, represents the excitation amplitude of each unit, represents the electric field distribution, H represents the conjugate transposed matrix, W represents the weighting coefficient of the target radiation pattern, A represents the intermediate connection matrix.

[0055] It provides the required excitation magnitude and phase for each array element. This ODE in its analytical form is key to achieving accurate cosecant-squared beam shapes because it ensures that the excitation distribution of the array elements meets the specified radiation requirements.

[0056] S3: Feed network design

[0057] The feed network is designed based on the calculated optimized excitation distribution ODE. The function of the feed network is to provide appropriate excitation for each array element to ensure that each element can radiate according to the predetermined excitation magnitude and phase.

[0058] When designing the feed network, it is important to ensure that it is compact and efficient. Compactness can reduce the size of the entire antenna array system, while efficiency ensures that the feed network can accurately transmit energy to each array element, thereby ensuring the overall performance of the array. Specifically, factors such as power allocation and phase adjustment need to be considered comprehensively to meet the excitation requirements of each array element.

[0059] S4: Far-field physical test in microwave anechoic chamber

[0060] S41: Far-field testing purpose and process

[0061] like Figure 3 As shown in the figure, the performance of the compact 18-element linear antenna array in the cosecant square mode is verified through a far-field physical test in a microwave darkroom. In this special environment of a microwave darkroom, external interference can be eliminated and the radiation characteristics of the antenna array can be accurately measured.

[0062] During the test, the antenna array prototype is placed at a suitable location in the microwave darkroom, and then professional test equipment is used to measure the radiation characteristics of the antenna array in the far field, including radiation pattern, gain and other parameters. Figure 4 The figure shows the reflection capability of the antenna array to the incident signal at different frequencies. The test results show that the working range of this antenna array is between 4.44-5.59GHz.

[0063] S42: Result comparison and performance verification

[0064] The test results are compared with the simulation results to ensure that the cosecant squared beam shape and sidelobe level (SLL) meet the expected requirements. This comparison can provide an intuitive understanding of the difference between the actual antenna array and the theoretical design.

[0065] The test results show that the maximum deviation between the measured field pattern and the desired cosecant-square curve is only 0.9 dB, which indicates that the designed compact 18-element linear microstrip antenna array can effectively realize the cosecant-square beam shape with high accuracy and reliability.

Claims

1. A cosecant square beam optimization method for long-distance communication, characterized in that: The long-distance communication cosecant square beam optimization method is applied to the long-distance communication cosecant square beam antenna array, the long-distance communication cosecant square beam antenna array comprising an FR4 dielectric substrate (2) and a plurality of U-shaped slot microstrip patch antenna units (1), the plurality of U-shaped slot microstrip patch antenna units (1) are flatly printed on the FR4 dielectric substrate (2), the plurality of U-shaped slot microstrip patch antenna units (1) are evenly spaced, the FR4 dielectric substrate (2) is arranged in a rectangular shape, and a cosecant square beam shape is realized, the center of the U-shaped slot microstrip patch antenna unit is connected to an SMA head and is connected to a feeding network, the FR4 dielectric substrate (2) is 3 mm thick, the relative dielectric constant is 4.35, and the loss tangent is 0.025, the number of the U-shaped slot microstrip patch antenna units (1) is 18, and they are symmetrically distributed on both sides of the center point, and the long-distance communication cosecant square beam optimization method comprises the following steps: S1: Antenna array design, including antenna element selection and array construction, determination of test point distribution and array tilt angle, and array prototype production; S2: Cosecant square beamforming, including constructing weighting coefficients and weighting matrices and calculating the excitation distribution ODE of array elements; S3: Design the feeding network based on the calculated optimized excitation distribution ODE; S4: Conduct far-field physical tests in a microwave darkroom and compare the test results with the simulation results. The weighted coefficient calculation formula constructed in step S2 is: ， in, Indicates p The weighting coefficient of the test points, Indicates q The weighting coefficient of each test point; Indicates the horizontal plane and the transmitting antenna array to the test point p The angle between the directions; Represents the horizontal plane and the transmitting antenna array to the test point q The angle between the directions, m represents the dimension of the weighting matrix, represents the beam start angle of the cosecant squared beam area; represents the beam coverage angle, The excitation distribution ODE of the array elements in step S2 is expressed as: ， in, represents the excitation amplitude of each unit, represents the electric field distribution, H represents the conjugate transposed matrix, W represents the weighting coefficient of the target radiation pattern, A represents the intermediate connection matrix.

2. The method for optimizing the cosecant square beam for long-distance communication according to claim 1, characterized in that: The U-shaped slot microstrip patch antenna unit (1) is made of a copper patch with a length of 、 Width , the interior is a U-shaped slot, the length of the slot is , width , the slot spacing is , the distance between the edge of the antenna unit and the U-shaped slot is , the distance between the feed point and the U-shaped slot is .

3. The method for optimizing the cosecant square beam for long-distance communication according to claim 1, characterized in that: The distance between the U-shaped slot microstrip patch antenna units (1) is 0.35λ, where λ is the wavelength.

4. The method for optimizing the cosecant square beam for long-distance communication according to claim 1, characterized in that: The step S1 distributes the test points on the spherical surface of the array far field area and sets the array tilt angle is 45°.

5. The method for optimizing the cosecant square beam for long-distance communication according to claim 1, characterized in that: The step S4 microwave darkroom far-field physical test includes placing the manufactured antenna array prototype at a suitable position in the microwave darkroom; using professional testing equipment to measure the radiation characteristics of the antenna array in the far field, and the measurement parameters include radiation pattern and gain.

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