An ultra-directive large-aperture non-periodic wide-angle scanning phased array

Abstract

The application discloses a kind of super directivity large spacing non-periodic wide-angle scanning phased array, belong to microwave antenna technical field.The phased array is composed of several super directivity large size antenna units non-periodic arrangement, and the non-periodic arrangement mode is obtained by perturbation method;Super directivity large size antenna unit includes dielectric substrate, ground plate, radiating patch, four parasitic patches, feed structure, wherein the shape of radiating patch and parasitic patch is obtained by genetic algorithm optimization topological structure, and the topological structure is triangular shape.The application adopts genetic algorithm to optimize the topological structure of radiating patch and parasitic patch, obtains super directivity large size antenna unit, increases antenna bandwidth, improves aperture utilization rate;In addition, the antenna unit is non-periodic array by perturbation method, and the grating lobe that appears when wide-angle scanning of large spacing array antenna is suppressed, and the cost of phased array antenna is reduced.

Description

Technical Field

[0001] This invention belongs to the field of microwave antenna technology, specifically relating to a large-spacing, non-periodic, wide-angle scanning phased array composed of subarrays of super-directional large-size antenna elements. Background Technology

[0002] Phased array radars are characterized by high scanning speed and high scanning accuracy. Compared to traditional mechanically rotating scanning radars, they significantly improve the spatial scanning capability of radars and offer more convenient processing of echo signals when using electromagnetic echo signals for angle and range measurements. Since the advent of the first electronically scanned phased array radar, phased array technology has been developing in the military radar field for decades. With the rapid development of digital circuits and manufacturing processes, phased array technology is gradually becoming more widespread in the civilian sector. However, the high cost of phased array radars remains a pressing engineering problem in the civilian technology field, with the cost of the T / R (transfer / receive) components accounting for approximately 75% of the radar system's cost. It is known that each antenna element corresponds to a set of T / R components. By increasing the spacing between elements in the same aperture plane, the number of elements can be reduced, thereby reducing the number of T / R components and achieving cost reduction. Therefore, solving the grating lobe problem in large-spacing sparse array scanning and researching wide-angle scanning phased arrays with large-spacing sparse arrays has become one of the important directions in the current engineering field.

[0003] Patent document CN113851833B (application number CN202111220999.7) discloses a grating lobe suppression wide-angle scanning phased array based on pattern reconfigurable subarray technology. It includes several periodically arranged unit pattern reconfigurable subarrays. By switching the direction of the unit pattern through the conduction of PIN diodes, the zero point of the unit pattern is aligned with the grating lobe position of the array factor pattern, thereby suppressing the grating lobes formed during scanning of a large-pitch sparse array. It achieves scanning ±30° in the large-pitch direction with an average sidelobe electrical charge of less than -8.6dB throughout the entire frequency band, and ±50° in the 0.5 times wavelength spacing direction with an average sidelobe electrical charge of less than -10.5dB. Although this method can effectively suppress grating lobes, the PIN diodes have many problems in practical engineering applications, such as complex power feeding, difficult maintenance, and easy detachment.

[0004] Patent document CN112803174B (application number CN202110104425.7) discloses a large-pitch phased array based on null-scanning antennas. The antenna elements within the array are arranged periodically with a spacing of 0.8λ. Each antenna element includes a parasitic patch layer, a radiating patch layer, an air layer, and a metal shell. By using null alignment, a large-angle, low-sidelobe two-dimensional phased array is achieved with a relatively small number of antenna elements. The element structure used in this method employs a multi-layer stacked design, which is complex to manufacture and suffers from problems such as complex PIN diode feeding and easy detachment.

[0005] Patent document CN213184579U (application number CN202022129135.1) discloses a two-dimensional phased array antenna with an aperiodic rectangular array arrangement. The subarrays are arranged in a rectangular grid. In the first quadrant, each subarray is diagonally connected end-to-end to form a non-overlapping outer stepped subarray. The second layer of stepped subarrays is arranged similarly. The other quadrants are symmetrical with the first quadrant, forming the entire large-pitch two-dimensional array. Changes in the antenna arrangement position affect the changes in the antenna array factor radiation pattern. By changing the position arrangement, grating lobes appearing during array factor radiation pattern scanning can be suppressed. However, due to the large-pitch arrangement leading to a reduction in the number of subarrays, the radiation characteristics of the antenna will inevitably be affected. Compared with a full-array antenna of the same aperture, the antenna gain and gain roll-off are both reduced.

[0006] Patent document CN109560392A (application number CN201811483957.0) discloses a low-cost wide-angle beam coverage phased array antenna system, which mainly includes a Luneburg lens, a system with switchable feed sources, and an RF front-end required for array transceiver. By switching the position of the feed source, the incident position of electromagnetic waves radiating from the Luneburg lens is changed, achieving a beam deflection effect. Furthermore, the Luneburg lens, with its gradient dielectric constant dielectric arrangement, can improve the radiation gain. However, this lens antenna is difficult to manufacture, especially the multilayer dielectric constant dielectric material. Currently, 3D printing technology cannot completely fabricate the required lenses on demand. Secondly, the lens antenna has a high profile, and the feed array needs to arrange the lens edges according to the curvature, thus posing certain problems in practical engineering applications.

[0007] In summary, large-spacing sparse arrays can typically suppress grating lobes using methods such as pattern reconfiguration, corps feed network design, non-periodic position arrangement, and loading lens metasurfaces. However, these methods come with problems such as gain loss, increased gain roll-off, and difficulty in conformal design. Therefore, while suppressing grating lobes, it is necessary to maintain the antenna's radiation characteristics, especially to reduce gain loss under the same aperture array. Summary of the Invention

[0008] To address the shortcomings mentioned in the above technical background, this invention proposes a super-directional, large-spacing, non-periodic wide-angle scanning phased array.

[0009] The technical solution adopted in this invention is as follows:

[0010] A super-directional, large-spacing, aperiodic, wide-angle scanning phased array is characterized in that the phased array is composed of several super-directional, large-size antenna elements arranged aperiodically, and the aperiodic arrangement is calculated by the perturbation method.

[0011] The super-directional large-size antenna element includes a dielectric substrate, a ground plane covering the back of the dielectric substrate, a radiating patch and four parasitic patches disposed on the front of the dielectric substrate, four metal through holes, and a feeding structure.

[0012] The wide side dimension of the super-directional large-size antenna element is 0.5λ-1.5λ, and the narrow side dimension is 0.5λ, where λ is the wavelength of the antenna center frequency in free space.

[0013] The center of the radiating patch coincides with the center of the super-directional large-size antenna element. The four parasitic patches are symmetrically arranged on both sides of the radiating patch, and the four metal through holes are located at the center of each parasitic patch.

[0014] The shapes of the radiating patch and the parasitic patch are obtained by optimizing the topology using a genetic algorithm, and the topology is triangular.

[0015] The super-directional large-size antenna element is fed by connecting to the T / R assembly through a coaxial feeding structure, and all elements work simultaneously when the phased array is in operation.

[0016] Furthermore, the design method of this phased array includes the following steps:

[0017] S1. Determine the operating frequency band of the phased array, thereby determining the size of the super-directional large-size antenna element.

[0018] S2. Determine the location of the radiation patch area, the parasitic patch area, and the metal via.

[0019] S3. Mesh the radiative patch region and the parasitic patch region respectively using a topology with triangular basic elements.

[0020] S4. Use a genetic algorithm to optimize the radiating patch and the parasitic patch to obtain their shapes.

[0021] In genetic algorithms, the objective function objV is set as follows:

[0022]

[0023] Where ω is the weight, f1 and f2 are the lowest and highest operating frequencies, respectively, S11 is the antenna S-parameter, and Gain is the actual gain of the antenna.

[0024] S5. Select a location that satisfies impedance matching as the feed point for the super-directional large-size antenna element.

[0025] S6. Perform electromagnetic simulation on the far-field radiation pattern of the electric field of the super-directional large-size element antenna to obtain the far-field radiation pattern data; combine the far-field radiation pattern data with the perturbation method to numerically optimize the aperiodic arrangement of the super-directional large-size antenna elements, and obtain a super-directional large-spacing aperiodic wide-angle scanning phased array.

[0026] The innovation of this invention is:

[0027] (1) The super-directional large-spacing aperiodic wide-angle scanning phased array proposed in this invention has an average spacing between the center of the array elements greater than 1λ. The aperiodic arrangement of the array elements suppresses the grating lobes that appear when the large-spacing array antenna scans wide angles. The antenna can achieve ±60° scanning in the XOZ plane with SLL below -8.4dB; and ±30° scanning in the YOZ plane with SLL below -7.5dB, effectively suppressing grating lobes.

[0028] (2) The super-directional large-spacing aperiodic wide-angle scanning phased array proposed in this invention can reduce the cost of phased array antennas and reduce the number of T / R components. When the antennas of the same aperture are fully arranged, the number of T / R components is 92. After the super-directional large-size unit is arranged aperiodically, the number of T / R components is 32, and the sparsity rate is 65.2%.

[0029] (3) The aperture of a typical microstrip patch antenna used in phased arrays is generally 0.5λ×0.5λ, with a relative bandwidth of about 6% and an actual gain of 5dBi to 7dBi. However, the aperture of the super-directional large-size antenna element proposed in this invention is twice that of a typical microstrip patch antenna, with a relative bandwidth of up to 17% and an actual gain of 8.6dBi. In a non-periodic array with the same number of array elements and array aperture, the phased array antenna composed of super-directional large-size element antennas can make up for the deficiencies of reduced aperture utilization, gain loss and narrow bandwidth caused by the reduction in the number of array elements.

[0030] (4) The super-directional large-spacing non-periodic wide-angle scanning phased array proposed in this invention solves the problems of grating lobe, gain loss and narrow bandwidth of non-periodic array wide-angle scanning antennas. The antenna only changes the topology of the top layer without adding any lenses or metasurfaces. The antenna is a single-layer structure, so the profile of the entire antenna array is very low and easy to use in actual industrial production. Attached Figure Description

[0031] Figure 1 This is a side view of the super-directional large-size antenna described in this invention;

[0032] Figure 2 This is a top view of the super-directional large-size antenna described in this invention;

[0033] Figure 3This is the S-parameter curve of the super-directional large-pitch non-periodic wide-angle scanning phased array antenna described in this invention;

[0034] Figure 4 This is the element pattern of the super-directional, large-pitch, non-periodic, wide-angle scanning phased array antenna described in this invention;

[0035] Figure 5 This is a top view of the super-directional, large-pitch, non-periodic, wide-angle scanning phased array antenna described in this invention;

[0036] Figure 6 This is the XOZ plane scanning pattern of the super-directional large-pitch non-periodic wide-angle scanning phased array antenna described in this invention;

[0037] Figure 7 This is the YOZ plane scanning pattern of the super-directional, large-spacing, non-periodic wide-angle scanning phased array antenna described in this invention.

[0038] Explanation of reference numerals: 1. Dielectric substrate, 2. SMA connector, 3. Metal ground plane, 4. Parasitic patch 1, 5. Parasitic patch 2, 6. Parasitic patch 3, 7. Parasitic patch 4, 8. Metal via 1, 9. Metal via 2, 10. Metal via 3, 11. Metal via 4, 12. Radiating patch, A. Antenna element. Detailed Implementation

[0039] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments.

[0040] A hyperdirectional antenna refers to an antenna that occupies a large radiating aperture with a non-array structure, while also possessing high radiating aperture utilization. The hyperdirectional large-size antenna element in this embodiment is as follows: Figure 1 and Figure 2 As shown, the super-directional large-size antenna element operates in the frequency band of 2.4GHz to 2.55GHz and includes a dielectric substrate (5.5mm Rogers RO3003 substrate), a ground plane covering the back of the dielectric substrate, a radiating patch and four parasitic patches disposed on the front of the dielectric substrate, and a feeding structure (fed by connecting to the T / R assembly through a coaxial feeding structure).

[0041] The super-directional large-size antenna element has a wide side dimension of 1λ and a narrow side dimension of 0.5λ, where λ is the wavelength of the antenna center frequency in free space. The center of the radiating patch coincides with the center of the super-directional large-size antenna element. Four parasitic patches are symmetrically arranged on both sides of the radiating patch. In this embodiment, the diameter of the metal through-hole is 1.6mm, located at the center of the parasitic patch, so that the parasitic patch is electrically connected to the ground. The shapes of the radiating patch and the parasitic patch are obtained by optimizing the topology using a genetic algorithm, and the topology is triangular.

[0042] Traditional microstrip patch antennas suffer from inherently narrow bandwidth. In contrast, the array element of this invention makes full use of the aperture by placing parasitic patches on both sides of the radiating patch. These parasitic patches, while coupled and resonating, expand the bandwidth of the radiating patch. At the same time, metal vias are loaded at the center of these parasitic patches to change their electric field distribution, reduce the Q value, and further expand the operating bandwidth.

[0043] In the design of the radiating and parasitic patches, the regions for the radiating and parasitic patches are first defined. Then, using meshing software, the regions are meshed using a triangular topology as the basic unit, dividing the complete PEC rectangular metal into several triangular metal pieces. The meshing criterion is to balance obtaining a good solution with speed. A finer mesh yields better results, but it significantly increases the complexity of the optimization problem. Therefore, in this embodiment, the mesh is divided into 119 sections, symmetrical along the x-axis and y-axis, to reduce the computational load of the optimization.

[0044] Finally, a genetic algorithm is designed to optimize the gridded region. The optimization aims to expand the working bandwidth of the array elements, improve their aperture utilization, and reduce cross-polarization components. In this embodiment, the objective function objV of the genetic algorithm is set as follows:

[0045]

[0046] Where ω is the weight, S11 is the antenna S-parameter, and Gain is the actual gain of the antenna.

[0047] The objective function consists of two parts. The first term is set to the minimum value of the S-parameters, which can also be calculated by measuring the bandwidth; the default weight is 1. The second term is the sum of antenna gains. To improve antenna gain, sampling can be performed every 0.5 GHz in the operating frequency band. ω is the weighting coefficient for the gain, which can be adjusted flexibly. It is important to note that in the genetic algorithm, the objective function always moves towards the smallest possible value. After multiple optimizations, the result is... Figure 2 The super-directional large-size antenna element shown in the figure has a topology-optimized radiating patch antenna and a parasitic patch.

[0048] like Figure 3 As shown, after optimization, the antenna bandwidth is extended to 2.2GHz to 2.8GHz, with a relative bandwidth of 17%.

[0049] like Figure 4 As shown, after optimization, the actual gain of the antenna is 8.6 dBi.

[0050] like Figure 5As shown, a perturbation method is used to perform aperiodic arrangement of a large-size hyperdirectional antenna. The array size is set to 4×8. The optimization target is to achieve a beamwidth of less than -10dB when scanning ±60° in the XOZ direction and a beamwidth of less than -10dB when scanning ±30° in the YOZ direction. The array elements are uniformly and periodically arranged with a spacing of 0.5λ in the XOZ direction and aperiodically arranged with a spacing of 1λ in the YOZ direction. By calculating the maximum beam pointing angle, gain, beamwidth, and other parameters of the large-size hyperdirectional antenna at different non-overlapping positions in the YOZ direction, the topology shown in the figure is obtained. This achieves a beamwidth of less than -8.4dB when scanning ±60° in the XOZ plane and a beamwidth of less than -7.5dB when scanning ±30° in the YOZ plane.

[0051] Table 1 shows the scanning characteristics of the super-directional, large-pitch, non-periodic, wide-angle scanning phased array antenna at various angles:

[0052] Table 1. Scanning data of the super-directional, large-pitch, non-periodic wide-angle scanning phased array antenna at various angles @3.5GHz

[0053]

[0054]

[0055] In summary, this invention discloses a super-directional, large-pitch, non-periodic wide-angle scanning phased array antenna. A genetic algorithm is used to optimize the topology of the radiating patch and parasitic patch to obtain a super-directional, large-size antenna element. The antenna element has a bandwidth of 2.2 GHz to 2.8 GHz, a relative bandwidth of 17%, and an actual gain of 8.6 dBi. This solves the inherent narrow bandwidth defect of traditional microstrip patch antennas and improves aperture utilization. Furthermore, the perturbation method is used to perform aperiodic arraying of the super-directional large-size antenna, with an average spacing between the center of the array elements greater than 1λ. The aperiodic arrangement of the array element positions suppresses the grating lobes that appear when the large-spacing array antenna scans at wide angles. The antenna achieves ±60° scanning in the XOZ plane with a SLL below -8.4dB; and ±30° scanning in the YOZ plane with a SLL below -7.5dB, and a sparsity of 65.2%. Compared with the number of T / R components (92) when the antenna of the same aperture is fully arrayed, the number of T / R components is reduced by 70, requiring only 32 T / R components, which greatly reduces the cost of the phased array radar. Moreover, the antenna adopts a single-layer PEC metal structure, which is simple to process and has a low profile height.

Claims

1. A super-directional, large-pitch, aperiodic, wide-angle scanning phased array, characterized in that, The phased array is composed of several super-directional large-size antenna elements arranged aperiodically, and the aperiodic arrangement is calculated by the perturbation method. The wide side dimension of the super-directional large-size antenna element is 0.5λ-1.5λ, and the narrow side dimension is 0.5λ, where λ is the wavelength of the antenna center frequency in free space; The super-directional large-size antenna unit includes a dielectric substrate, a ground plane covering the back of the dielectric substrate, a radiating patch and four parasitic patches disposed on the front of the dielectric substrate, four metal through holes, and a feeding structure. The center of the radiating patch coincides with the center of the super-directional large-size antenna element, and the four parasitic patches are symmetrically arranged on both sides of the radiating patch. The four metal through holes are located at the center of each parasitic patch. The shapes of the radiating patch and the parasitic patch are obtained by optimizing the topology using a genetic algorithm, and the topology is triangular. The super-directional large-size antenna element is fed by connecting to the T / R assembly through a coaxial feeding structure. All elements work simultaneously when the phased array is in operation. The design method of this phased array includes the following steps: S1. Determine the operating frequency band of the phased array, thereby determining the size of the super-directional large-size antenna element; S2. Determine the locations of the radiating patch area, the parasitic patch area, and the metal vias; S3. Mesh the radiating patch region and the parasitic patch region respectively using a topology with triangular basic elements; S4. Use a genetic algorithm to optimize the radiating patch and the parasitic patch to obtain their shapes; In genetic algorithms, the objective function Set to: in, As weight, , These are the lowest and highest operating frequencies, respectively. For antenna S-parameters, This represents the actual gain of the antenna; S5. Select a location that satisfies impedance matching as the feed point for the super-directional large-size antenna element; S6. Perform electromagnetic simulation on the far-field radiation pattern of the electric field of the super-directional large-size element antenna to obtain the far-field radiation pattern data; combine the far-field radiation pattern data with the perturbation method to numerically optimize the aperiodic arrangement of the super-directional large-size antenna elements, and obtain a super-directional large-spacing aperiodic wide-angle scanning phased array.

Images