Circularly polarized wide-angle scanning phased array antenna

Abstract

The invention discloses a circularly polarized wide-angle scanning phased-array antenna, which comprises a plurality of quaternary sub-arrays, each quaternary sub-array comprises four antenna units, the feed phases of the four antenna units are sequentially subjected to 90-degree phase compensation to form the quaternary sub-array, and the plurality of quaternary sub-arrays are sequentially combined to form the phased-array antenna. A metamaterial wide-scanning matching structure is loaded above an antenna array plane, a double-layer structure is adopted, correction is improved through phase compensation, the phased-array antenna has the large-angle scanning capacity of + / -70 degrees, and the axial ratio at the center frequency point 29.5 GHz and at each scanning angle is smaller than 1.5 dB. The invention provides the circularly polarized wide-angle scanning phased-array antenna, the phased-array antenna has the large-angle scanning capability of + / -70 degrees, the axial ratio in the scanning range is within 3dB, and the circularly polarized standard can still be met.

Description

Technical Field

[0001] The present invention relates to the technical field of antennas, and in particular, to a circularly polarized wide-angle scanning phased array antenna. Background Art

[0002] With the development of satellite communication technology, people have higher and higher requirements for mobile satellite ground station communication systems. Millimeter waves provide a wider frequency band with their rich frequency bands, which helps to meet the growing data transmission needs and support higher data rates. This is crucial for high-speed data communication and large-capacity information transmission. Therefore, millimeter wave communication has received extensive attention.

[0003] However, millimeter wave signals will be subject to certain absorption when propagating in the atmosphere. However, the propagation losses of specific millimeter wave frequency bands (such as 24.25 - 29 GHz and E-band (71 - 76 / 81 - 86 GHz)) are relatively low and are considered to be relatively excellent millimeter wave bands suitable for wireless communication. Circularly polarized (CP) antennas can effectively reduce the multipath effect and polarization mismatch problems compared with linearly polarized antennas, which is of great significance for improving communication quality and reliability, and has advantages such as more miniaturized design. Therefore, it has received extensive attention in the field of satellite communication. In addition, for millimeter wave communication that requires long-distance transmission, high-gain antennas are indispensable. Therefore, circularly polarized antennas with both broadband characteristics and high gain naturally become the first choice for millimeter wave communication systems. The circularly polarized wide-angle scanning phased array antenna has excellent beam scanning and anti-interference capabilities, making it have broad application prospects in mobile satellite communication systems. Therefore, millimeter wave circularly polarized wide-angle scanning phased array antennas have gradually become a research hotspot among domestic and foreign experts and scholars.

[0004] China has made great progress in the basic theory, key technologies, and system development of polarization phased array radars. Many polarization phased array radars have been developed one after another. For example, the phased array radars developed by the 23rd Research Institute of Aerospace Science and Industry Corporation and the 14th Research Institute of China Electronics Technology Group Corporation already have full polarization measurement capabilities. Circularly polarized antennas are widely used in radar transceiver antennas and satellite communication because they can better overcome the multipath effect, polarization mismatch loss, and the influence caused by the Faraday rotation ionosphere. Some studies have designed ultra-wide-angle circularly polarized phased array antennas and achieved one-dimensional scanning within a certain range. For example, a new type of low-profile, "f"-shaped waveguide slot circular polarizer combined with a ridge waveguide standing wave slot array antenna has achieved a Ka-band circularly polarized wide-angle scanning phased array antenna with excellent measured performance indicators.

[0005] Beam scanning usually brings problems such as gain degradation, beam broadening, and deterioration of pattern symmetry. In addition, beam scanning also reduces the orthogonality of electric field polarization, causes cross-polarization coupling, and leads to polarization measurement errors. Currently, there is a lack of research on millimeter-wave circular polarization wide-angle scanning technology. The existing work has a limited scanning angle range and is difficult to meet the requirements of wide-angle scanning and circular polarization standards under wide-angle scanning.

[0006] In summary, although certain progress has been made in the circular polarization phased array wide-angle scanning technology, there are still challenges and deficiencies in the problems brought by beam scanning and the complexity of the wide-angle scanning structure. Summary of the Invention

[0007] The purpose of the present invention is to provide a circular polarization wide-angle scanning phased array antenna, which has a large-angle scanning ability of ±70°, and the axial ratio within the scanning range is within 3 dB, still meeting the circular polarization standard.

[0008] The technical solution adopted by a circular polarization wide-angle scanning phased array antenna disclosed by the present invention is as follows:

[0009] A circular polarization wide-angle scanning phased array antenna includes a plurality of four-element sub-arrays. The four-element sub-array includes four antenna elements. The feeding phases of the four antenna elements are compensated by 90° in sequence to form a four-element sub-array. A plurality of the four-element sub-arrays are combined in sequence to form a phased array antenna. A metamaterial wide-scan matching structure is loaded above the antenna array surface and adopts a double-layer structure, and is improved and corrected through phase compensation. The phased array antenna has a large-angle scanning ability of ±70°, and at the center frequency of 29.5 GHz, the axial ratio at each scanning angle is less than 1.5 dB.

[0010] As a preferred solution, the antenna element includes a feeding patch and two groups of radiation patches arranged from bottom to top. The feeding patch and the radiation patches are both arranged on the surface of the semi-cured board. Dielectric boards are provided below the feeding patch, between the feeding patch and the radiation patches, between the two groups of radiation patches, and above the radiation patches. The feeding patch and the two groups of radiation patches are spaced from each other pairwise through the dielectric boards. An air cavity is provided between the feeding patch and the radiation patch. The radiation patch is provided with a through hole penetrating into the air cavity. An SMP connector is also provided below the feeding patch, and metallized vias are provided in the dielectric board.

[0011] As a preferred solution, the feeding patches of the four antenna elements are rotated by 90° in sequence around the center of the four-element sub-array, so that the four-element sub-array forms a 2×2 square structure.

[0012] As a preferred solution, the radiation patches on the second semi-cured sheet are in a 4×4 array structure.

[0013] As a preferred solution, the number of the four - element sub - arrays is 5 groups, forming the phased array antenna of 2×10.

[0014] As a preferred solution, the metamaterial wide - scan matching structure of the phased array antenna is a conformal structure.

[0015] The beneficial effects of a circularly polarized wide - angle scanning phased array antenna disclosed by the present invention are as follows: This structure has the high - frequency large - angle scanning ability of ±70° in one - dimensional level. While achieving large - angle wide - angle scanning, it ensures that the circular polarization axial ratio is always less than 1.5 dB. In addition, the designed metamaterial wide - angle matching structure realizes the enhancement of normal gain. Even when affected by inter - array influence, although the gain drops significantly during high - frequency large - angle scanning, the axial ratio within the scanning range is still within 3 dB, still meeting the circular polarization standard and improving the problem of circular polarization axial ratio deterioration under large - angle beam scanning. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the antenna element structure of a circularly polarized wide - angle scanning phased array antenna of the present invention.

[0017] Figure 2 It is a schematic diagram of the four - element sub - array structure of a circularly polarized wide - angle scanning phased array antenna of the present invention.

[0018] Figure 3 It is a schematic diagram of the structure of a circularly polarized wide - angle scanning phased array antenna of the present invention.

[0019] Figure 4 It is the normal direction pattern of a circularly polarized wide - angle scanning phased array antenna of the present invention at 29.5 GHz.

[0020] Figure 5 It is the scanning direction pattern of a circularly polarized wide - angle scanning phased array antenna of the present invention at 29.5 GHz.

[0021] Figure 6 It is a cross - sectional view of the antenna element of a circularly polarized wide - angle scanning phased array antenna of the present invention.

[0022] Figure 7 It is a schematic diagram of the antenna element component structure of a circularly polarized wide - angle scanning phased array antenna of the present invention.

[0023] Figure 8 It is a schematic diagram of the feeding patch current vector of a circularly polarized wide - angle scanning phased array antenna of the present invention.

[0024] Figure 9 It is a schematic diagram of the radiation patch current vector of a circularly polarized wide - angle scanning phased array antenna of the present invention.

[0025] Figure 10 It is the unit voltage standing - wave ratio diagram of a circularly polarized wide - angle scanning phased array antenna of the present invention.

[0026] Figure 11 It is the 29.5GHz element pattern of a circularly polarized wide-angle scanning phased array antenna of the present invention.

[0027] Figure 12 It is the 29.5GHz element axial ratio diagram of a circularly polarized wide-angle scanning phased array antenna of the present invention.

[0028] Figure 13 It is the four-element pattern of a circularly polarized wide-angle scanning phased array antenna of the present invention.

[0029] Figure 14 It is the four-element active voltage standing wave ratio diagram of a circularly polarized wide-angle scanning phased array antenna of the present invention.

[0030] Figure 15 It is the comparison diagram of adjacent port coupling improvement of a circularly polarized wide-angle scanning phased array antenna of the present invention.

[0031] Figure 16 It is the four-element pattern of a circularly polarized wide-angle scanning phased array antenna of the present invention after loading a metamaterial wide-scan matching structure.

[0032] Figure 17 It is the wide-angle scanning diagram of different phase compensation unit tilts of a circularly polarized wide-angle scanning phased array antenna of the present invention. Detailed implementation manners

[0033] The present invention will be further elaborated and described below in conjunction with specific embodiments and the accompanying drawings of the specification:

[0034] Please refer to Figures 1 to 3 , a circularly polarized wide-angle scanning phased array antenna 30, includes a plurality of four-element sub-arrays 20. The four-element sub-array 20 includes four antenna elements 10. The feeding phases of the four antenna elements 10 are sequentially compensated by 90° to form the four-element sub-array 20. Further, the circularly polarized wide-angle scanning matching structure is made of metamaterial. The use of its double-layer structure, compared with the non-wide-angle scanning matching structure and the single-layer wide-angle scanning matching structure, although it will cause a decrease in the maximum gain, but as the scanning angle increases, the gain decrease under the double-layer wide-angle scanning matching structure is relatively slow, and it has advantages in impedance matching and pattern symmetry.

[0035] The number of four-element sub-arrays 20 is 5 groups, forming a 2×10 phased array antenna 30. The metamaterial wide-scan matching structure is loaded above the antenna array surface and a double-layer structure is adopted. Through phase compensation for improvement and correction, the phased array antenna 30 has a large-angle scanning ability of ±70°. At the center frequency point of 29.5GHz, the axial ratio at each scanning angle is less than 1.5dB. The metamaterial wide-scan matching structure of the phased array antenna 30 is a conformal structure.

[0036] This structure has the ability of high-frequency large-angle scanning in the one-dimensional plane with an angle range of ±70°. While achieving large-angle wide-angle scanning, it ensures that the circular polarization axial ratio is always less than 1.5 dB. In addition, the designed metamaterial wide-angle matching structure realizes the enhancement of normal gain. Even affected by inter-element influence, although the gain drops significantly during high-frequency large-angle scanning, the axial ratio within the scanning range is still within 3 dB, still meeting the circular polarization standard and improving the problem of deterioration of the circular polarization axial ratio under large-angle beam scanning. Figure 4 、 Figure 5 And Table 1 characterize the gain, 3 dB beam width of the scanning plane, and axial ratio at the central frequency point of 29.5 GHz.

[0037] Table 1: Statistical results of the horizontal plane scanning pattern of the 29.5 Hz array antenna

[0038]

[0039]

[0040] Please refer to Figure 6 and Figure 7 In the above solution, the antenna element 10 includes a feeding patch 11 and two groups of radiating patches 12 arranged from bottom to top. The feeding patch 11 and the radiating patches 12 are both arranged on the surface of the semi-cured board 13. Dielectric boards 14 are provided below the feeding patch 11, between the feeding patch 11 and the radiating patches 12, between the two groups of radiating patches 12, and above the radiating patches 12. The feeding patch 11 and the two groups of radiating patches 12 are spaced from each other pairwise through the dielectric boards 14. An air cavity 15 is provided between the feeding patch 11 and the radiating patches 12. The radiating patch 12 is provided with a through hole 17 penetrating into the air cavity 15. An SMP connector 16 is further provided below the feeding patch 11, and a metallized through hole 17 is provided in the dielectric board 14.

[0041] The feeding patches 11 of the four antenna elements 10 are sequentially rotated by 90° around the center of the four-element subarray 20, so that the four-element subarray 20 forms a 2×2 square structure, and the radiating patches 12 on the second semi-cured sheet are in a 4×4 array structure.

[0042] Figure 8 and Figure 9 respectively show the schematic diagrams of the current vectors of the feeding patch 11 and the radiating patch 12 of the antenna within one period. The running trajectories of the surface currents of the feeding patch 11 and the radiating patch 12 are marked with blue arrows. It can be seen from the schematic diagram of the current vector in Figure 4 that the feeding patch 11 and the radiating patch 12 have a 90° phase difference within a quarter period and rotate in the clockwise direction. At two frequency points, the surface currents of the driving patch and the parasitic patch both show the same clockwise rotation property, indicating that the antenna has circular polarization characteristics and the working polarization is right-handed circular polarization.

[0043] Figure 10 It can be seen that the VSWR of the unit is < 1.6 in the range of 27.5 GHz - 31 GHz, and the impedance matching range is very wide, but the circular polarization characteristic of the unit is relatively poor.

[0044] Reference Figure 11 and Figure 12 , the axial ratio of the normal direction at the center frequency of 29.5 GHz is only 5.6 dB. Therefore, the unit is rotated and arranged, Figure 2 is a schematic diagram of a four - element array. Each unit is rotated and the phase difference is compensated, achieving better circular polarization characteristics. The simulation calculation results

[0045] Table 2: Pattern statistics of the four - element array

[0046]

[0047]

[0048] Figure 13 and Figure 14 From the simulation results in Table 2, it can be seen that after the rotation arrangement, taking the four - element array as a sub - array, its axial ratio has been significantly improved, the circular polarization performance has been greatly enhanced, and the axial ratio within the frequency band is less than 1 dB. The impedance matching of the antenna is affected by the coupling of different unit ports, deteriorating to a certain extent, resulting in a certain degree of deterioration of the active standing wave. The active voltage standing wave ratio is slightly higher than 2 at the high frequency of 31 GHz.

[0049] By loading the metamaterial wide - scan matching structure above the antenna array surface and simulating and optimizing the metamaterial structure and height, while optimizing the impedance matching and pattern, the port coupling results are also improved to a certain extent, such as Figure 15 . It can be seen that after loading the metamaterial wide - scan matching structure, the port isolation between adjacent antennas has been improved by 6 dB within the frequency band, and this structure has almost no influence on the port isolation of the diagonal units.

[0050] Table 3: Pattern statistics of the four - element array

[0051]

[0052] From Figure 16 and Table 3, it can be seen that due to the improvement of the port isolation, the antenna gain has a small increase and the circular polarization characteristic remains basically unchanged. Applying this structure to a large - scale array, due to its decoupling characteristics, the scanning range of the array can be increased.

[0053] Please refer to Figure 17 , the wide - angle scanning with unit tilt is a way to expand the scanning angle. Here, the unit tilt is analyzed.

[0054] Normal gain is 16.4 dBi, scanning range is ±55°, gain is 12.4 dBi, scanning phase difference is improved, from 135 deg to 120 deg, and the theoretical phase difference for 55° scanning is 130 deg.

[0055] After compensating the phase (delta = 30 deg), the normal gain is 15.3 dBi, scanning range is ±55°, gain is 12.9 dBi, scanning range is ±64°, and gain is 11.5 dBi.

[0056] After compensating the phase (delta = 20 deg), the normal gain is 14.0 dBi, scanning range is ±55°, gain is 13.0 dBi, scanning range is ±63°, and gain is 11.9 dBi.

[0057] Table 4 Wide-angle scanning statistics for different tilts of phase compensation units

[0058] 20deg 30deg Far-field gain / dBi (axial ratio / dB) 13.0(0.8) 14.2(0.4) ±55° gain / dBi (axial ratio / dB) 13.2(2.9) 13.2(2.4) ±65° gain / dBi (axial ratio / dB) 12.1(3.5) 12.0(3.6) ±70° gain / dBi (axial ratio / dB) 10.6(4.0) 10.6(4.1)

[0059] Also considering the conformal scanning requirements of the carrier, the metamaterial wide-scan matching is designed as a conformal structure, improving its carrier adaptability and practicality.

[0060] Table 5: Horizontal plane scanning pattern statistics of 27.5 Hz array antenna

[0061]

[0062] To verify that the invention can ensure normal operation within the working frequency, the normal pattern, scanning pattern and other performances at two frequencies, the center frequency of 29.5 GHz and the maximum frequency of 31 GHz, are selected for feasibility analysis and verification. The specific data are shown in Table 6 and Table 7 below.

[0063] Table 6: Horizontal plane scanning pattern statistics of 29.5 Hz array antenna

[0064]

[0065] Table 7: Horizontal plane scanning pattern statistics of 31 Hz array antenna

[0066]

[0067]

[0068] Through simulation calculations, it can be seen that the array antenna has a large-angle scanning ability of ±70°, and at the center frequency of 29.5 GHz, the axial ratio at each scanning angle is less than 1.5 dB, with high polarization purity. Affected by the inter-element influence, the gain drops significantly during high-frequency large-angle scanning, but its axial ratio is still within 3 dB and can be used normally.

[0069] In summary, the invention and design of the Ka-band one-dimensional circularly polarized phased array conformal metamaterial wide-angle scanning technology has the high-frequency large-angle scanning ability of ±70° in one dimension. While achieving large-angle wide-angle scanning, it ensures that the circular polarization axial ratio is always less than 1.5 dB. In addition, the metamaterial wide-angle matching structure designed by the invention realizes enhanced normal gain, broadens the 3 dB beam width in the scanning plane, and improves the deterioration problem of the circular polarization axial ratio under large-angle beam scanning, providing a novel one-dimensional circularly polarized phased array metamaterial wide-angle scanning technology for the development of circularly polarized phased array wide-angle scanning technology.

[0070] The present invention provides a circularly polarized wide-angle scanning phased array antenna. This structure has the high-frequency large-angle scanning ability of ±70° in one dimension. While achieving large-angle wide-angle scanning, it ensures that the circular polarization axial ratio is always less than 1.5 dB. In addition, the designed metamaterial wide-angle matching structure realizes enhanced normal gain. Even affected by inter-element influence, although the gain drops significantly during high-frequency large-angle scanning, the axial ratio within the scanning range is still within 3 dB and can still meet the circular polarization standard, improving the deterioration problem of the circular polarization axial ratio under large-angle beam scanning.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A circularly polarized wide-angle scanning phased array antenna, characterized in that: The invention comprises a plurality of quaternary sub-arrays, each of which comprises four antenna units. The feeding phases of the four antenna units are sequentially phase-compensated by 90° to form a quaternary sub-array. The plurality of quaternary sub-arrays are sequentially combined to form a phased array antenna. A metamaterial wide-scan matching structure is loaded above the antenna array surface, and a double-layer structure is adopted. Phase compensation is used to improve correction. The phased array antenna has a large-angle scanning capability of ±70°. At a center frequency of 29.5 GHz, the axial ratio at each scanning angle is less than 1.5 dB.

2. The circularly polarized wide-angle scanning phased array antenna according to claim 1, characterized in that: The antenna unit includes a feed patch and two groups of radiation patches from bottom to top, and the feed patch and the radiation patch are both arranged on the surface of the semi-cured board. Dielectric plates are arranged below the feed patch, between the feed patch and the radiation patch, between the two groups of radiation patches, and above the radiation patch. The feed patch and the two groups of radiation patches are spaced apart from each other by the dielectric plates, and an air cavity is arranged between the feed patch and the radiation patch, the radiation patch is provided with a through hole penetrating into the air cavity, an SMP connector is also arranged below the feed patch, and a metallized through hole is arranged in the dielectric plate.

3. The circularly polarized wide-angle scanning phased array antenna according to claim 2, characterized in that: The feeding patches of the four antenna units are rotated 90° around the center of the four-element sub-array in sequence, so that the four-element sub-array forms a 2×2 square structure.

4. The circularly polarized wide-angle scanning phased array antenna according to claim 2, characterized in that: The radiation patches on the second prepreg are in a 4×4 array structure.

5. The circularly polarized wide-angle scanning phased array antenna according to claim 1, characterized in that: The number of the four-element sub-arrays is 5, forming 2×10 phased array antennas.

6. The circularly polarized wide-angle scanning phased array antenna according to claim 1, characterized in that: The metamaterial wide-scan matching structure of the phased array antenna is a conformal structure.

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