Dual circular polarization metasurface array antenna structure

Abstract

The invention discloses a dual-circular-polarization metasurface array antenna structure. The upper surface of a radiation layer of a structural unit is provided with a metasurface composed of a plurality of chamfered triangular patterns; a slit metal ground structure is arranged on the upper surface of the coupling layer; the upper surface of the feed layer is provided with a U-shaped strip-shaped feeder line, two ends of the U-shaped strip-shaped feeder line are fed by coaxial probes, one port is selected for feeding, and the other port is connected with a 50-ohm load for left-handed or right-handed circularly polarized radiation; metallized isolation through holes are arranged between the units. According to the invention, the single transmission line is used for feeding the radial gap, the sub-wavelength metasurface with equal amplitude and 90-degree phase difference is excited to realize circular polarization radiation, and the structure can realize + / -70-degree two-dimensional beam scanning in the Ka frequency band. Compared with a circularly polarized antenna realized by a double-feed structure, the number of dielectric layers is reduced, and the profile height is only 0.084 central frequency point wavelength. The millimeter wave satellite communication antenna is suitable for being applied to a millimeter wave satellite communication antenna system of the LTCC technology.

Description

Technical Field

[0001] The invention belongs to the technical field of radar antennas, and in particular relates to a dual circular polarization supersurface array antenna structure. Background Art

[0002] Dual circular polarization has the advantages of strong anti-interference ability and resistance to channel path fading, and is widely used in satellite communication systems. Among them, the microstrip patch antenna is the simplest and most popular antenna radiation unit form for realizing circularly polarized waves. This type of antenna has the advantages of low profile, light weight, low cost, and easy compatibility with printed circuits. However, its impedance bandwidth and axial ratio bandwidth are both narrow and the gain is relatively low. Although there are many technologies that can overcome this shortcoming, such as loading U-shaped gaps, loading parasitic structures, using non-contact capacitive feeding, loading back cavities, or increasing the thickness of dielectric substrates, these methods also have problems such as high profile or limited bandwidth improvement. At the same time, the above-mentioned microstrip antenna arrays generally have the problem of severe gain drop during large-angle scanning and narrow wide-angle scanning bandwidth.

[0003] In addition, with the rapid development of wireless communication technology, antennas are required to have excellent performance such as low profile, miniaturization, and broadband. The traditional circularly polarized antenna feeding part generally adopts dual-feed or multi-feed design to produce circularly polarized radiation. This design makes the overall structure of the antenna more complicated, which easily leads to a higher overall profile of the antenna and the center frequency of the axial ratio is easily affected. When the above feeding form is used as the signal input in the phased array system, in order to produce a phase difference, each antenna unit needs to be connected to two or more sets of phase shifters, which increases the complexity of the component circuit and control circuit design.

[0004] In recent years, metasurface antennas have been able to break through the limitations of traditional antenna design, improve traditional antenna performance indicators, and to a certain extent effectively improve the design freedom of antennas. Through multiple tiny units, it can flexibly and effectively control the phase, polarization mode, propagation mode and other characteristics of electromagnetic waves, and has been widely used in the design of planar antennas. Metasurface structures have great development prospects in reducing antenna profiles and expanding axial ratio bandwidths. Compared with the complexity of traditional circularly polarized antennas, the use of metasurface technology to generate circular polarization can be achieved in a compact antenna structure, and can better adjust circular polarization, and the axial ratio frequency is more stable. For example, the published patents CN202211147510.2 "Wide-beam dual-circularly polarized metasurface antenna unit, implementation method and phased array antenna", CN202110786809.1 "Millimeter-wave wide-angle scanning phased array antenna based on metasurface", CN202011059485.3 "A low-profile broadband base station antenna and communication equipment based on metasurface", etc., all of the above antennas use square patches as units of the metasurface structure. Because the metasurface needs to meet a certain number and period of units to have directional pattern diversity and discrete current characteristics, square patches generally require more than 16 square patches within the antenna array unit dimension. When the antenna operates in the frequency band above Ka, the size of a single metasurface unit is difficult to meet the processing accuracy requirements, and the design freedom is also relatively limited. At the same time, there is an air layer or a multi-layer dielectric between the coupling gap and the metasurface unit, so the overall profile is high. Summary of the invention

[0005] In order to overcome the shortcomings and deficiencies of the prior art, the present invention proposes a dual circular polarization metasurface array antenna structure to achieve the purpose of high power resistance and wide angle scanning. The present invention has the characteristics of low profile, small size and simple structure, and can ensure that the beam has good circular polarization characteristics at each scanning angle and axis ratio within the working frequency band.

[0006] In order to achieve the purpose of the present invention, the present invention proposes a dual circularly polarized supersurface array antenna structure, wherein the array antenna structure is formed by an array of multiple supersurface array antenna units; the supersurface array antenna unit is composed of a radiation layer, a coupling layer and a feeding layer stacked in sequence from top to bottom; the upper surface of the radiation layer is provided with a supersurface composed of multiple cut-angle triangle patterns; the upper surface of the coupling layer is provided with a metal ground structure with gaps; the upper surface of the feeding layer is provided with a U-shaped strip feed line, both ends of which are fed by coaxial probes, one of the ports is selected for feeding, and the other port is connected to a 50 ohm load for left-handed or right-handed circularly polarized radiation; a metallized isolation through-hole is provided between each supersurface array antenna unit.

[0007] Furthermore, the metasurface structure of the radiation layer unit is formed by rotating a square patch by 45 degrees to form a crisscross groove, and then cutting off four right angles to finally form 8 cut-corner triangle patterns.

[0008] Furthermore, the metal ground of the coupling layer unit has a radial gap assembly, which is formed by rotating the gap along the positive direction of the Y axis from the center point around the Z axis toward the X axis and replicating it 4 times every 45 degrees.

[0009] Furthermore, the U-shaped strip feeder of the feed layer unit is provided with an impedance matching adjustment section at a position corresponding to the center of each slot, and the length and width of each adjustment section are changed to optimize the circular polarization axis ratio.

[0010] Compared with the prior art, the present invention has the following beneficial effects:

[0011] 1) The present invention uses only three layers of dielectric stacking design to realize the dual circular polarization antenna structure, which has the characteristics of low profile;

[0012] 2) The present invention adopts radial coupling slots and U-shaped stripline feeding design to excite electromagnetic energy to form transmission and coupling, thereby reducing the difficulty of generating circularly polarized waves;

[0013] 3) The present invention cleverly utilizes the cut-corner triangular metasurface units as radiators, which reduces the number required by half compared to the square patch format, is suitable for wide-angle scanning array design, and has a symmetrical two-dimensional scanning pattern. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0015] Figure 1 It is a top view schematic diagram of a dual circular polarization metasurface array antenna structure;

[0016] Figure 2 It is a schematic side view of a unit of a dual circular polarization metasurface array antenna structure;

[0017] Figure 3 It is a three-dimensional layered diagram of the unit cells of a dual circularly polarized metasurface array antenna structure;

[0018] Figure 4 It is an infinite array unit standing wave of a dual circularly polarized metasurface array antenna structure;

[0019] Figure 5 It is an infinite array unit pattern of a dual circularly polarized metasurface array antenna structure;

[0020] Figure 6 It is an 8×8 array scanning beam axis ratio of a dual circularly polarized metasurface array antenna structure;

[0021] Figure 7(a), (b), and (c) are the scanning patterns of a dual circularly polarized metasurface array antenna structure at 27 GHz, 29 GHz, and 31 GHz;

[0022] The reference numerals in the figure are: radiation layer 1, coupling layer 2, feeding layer 3, metasurface structure 101, coupled metal ground 201, slot assembly 202, U-shaped feed line 301, impedance matching adjustment section 302, left-hand circular polarization feeding probe 303, right-hand circular polarization feeding probe 304, and metal ground 305. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0024] A dual circularly polarized metasurface array antenna structure, the array antenna structure is formed by an array of multiple metasurface array antenna units; the metasurface array antenna units are composed of a radiation layer, a coupling layer and a feeding layer stacked in sequence from top to bottom; the upper surface of the radiation layer is provided with a metasurface composed of multiple cut-angle triangle patterns; the upper surface of the coupling layer is provided with a metal ground structure with gaps; the upper surface of the feeding layer is provided with a U-shaped strip feeder, both ends of which are fed by coaxial probes, one of the ports is selected for feeding, and the other port is connected to a 50-ohm load for left-handed or right-handed circularly polarized radiation; metallized isolation through holes are provided between each metasurface array antenna unit.

[0025] Example

[0026] like Figure 1 As shown, Figure 1 This is a top view of a preferred embodiment of the present invention. This embodiment is arranged in a rectangular grid, and is an 8×8 sub-array of an ultra-thin phased array antenna structure based on an artificial magnetic conductor. In order to ensure that no grating lobes appear when the array scans to 70°, the unit spacing is half of the wavelength corresponding to the highest frequency of the working frequency band.

[0027] like Figure 2 As shown, Figure 2 This is a schematic diagram of the side view of the unit of the preferred embodiment of the present invention, which consists of a radiation layer 1, a coupling layer 2 and a feed layer 3 from top to bottom. In this embodiment, the LTCC process is used, and the three layers of dielectric are all ceramics, with a dielectric constant of 5.5 and a loss tangent of 0.0008. The thickness of the radiation layer dielectric is 0.36mm, the thickness of the coupling layer dielectric is 0.12mm, the thickness of the feed layer dielectric is 0.36mm, and the metal pattern material is silver with a thickness of 0.006mm. The overall thickness of the antenna structure is 0.864mm.

[0028] like Figure 3 As shown, Figure 3 It is a three-dimensional layered diagram of the unit of the preferred embodiment of the present invention. The super surface structure of the radiation layer unit is formed by rotating a 45-degree square patch with a side length of 3.3mm to open a 0.2mm M-shaped groove, and then cutting off four right angles with a side length of 0.4mm, finally forming 8 cut-angle triangle patterns. The metal ground of the coupling layer unit has a radial gap assembly, which is formed by rotating the gap along the positive direction of the Y axis around the Z axis toward the X axis every 45 degrees and replicating 4 times. The width of each gap is 0.21mm. In this embodiment, the length of each coupling gap is 1.05mm. The U-shaped strip feeder of the feed layer unit is provided with an impedance matching adjustment section at the corresponding position of each gap center, and the length and width of each adjustment section are changed to optimize the circular polarization axis ratio. In this embodiment, the U-shaped strip line width is 0.17mm, the U-shaped radius is 0.7mm, and there are five square segments with impedance matching adjustment sections of 0.3mm.

[0029] In order to obtain the performance of the unit, the periodic boundary conditions in the electromagnetic simulation software are used to simulate and verify it. Figure 4 As shown, Figure 4 This is the infinite array unit standing wave of the preferred embodiment of the present invention. In this embodiment, within the frequency band of 27 GHz to 31 GHz, when scanning to 60°, the standing wave is less than 5. When scanning to 75°, the standing wave is less than 6.

[0030] like Figure 5 As shown, Figure 5 This is the infinite array unit directional pattern of the preferred embodiment of the present invention, and the unit gain range in the frequency band is 3.53dB to 4.63dB.

[0031] like Figure 6 As shown, Figure 6 This is the 8×8 array scanning beam axial ratio of the preferred embodiment of the present invention. Within the scanning range of ±70°, the axial ratio of the two-dimensional scanning is less than 5.6 dB, which shows that it has good circular polarization characteristics within the scanning range.

[0032] like Figure 7 As shown in (a), (b), and (c), taking left-hand polarization as an example, the directional diagrams of circular polarization are analyzed respectively, and the beam scanning angles are 0°, ±10°, ±20°, ±30°, ±40°, ±50°, ±60°, and ±70°, which are the scanning directional diagrams of the embodiment of the present invention at 27 GHz, 29 GHz, and 31 GHz respectively. It can be seen from the results that when the two dimensions are scanned to 70° respectively, the maximum gain decrease is 8 dB, and the scanning beam is symmetrical.

[0033] The present invention only describes the Figure 3The periodic unit structure described can be expanded to any practical finite array according to the needs of practical applications. It is common knowledge in the art how to use antenna units to design arrays. The above is an embodiment of the present invention, and it should be understood that it is only presented in an exemplary form and is not restrictive. Therefore, various changes in form and details can be made without departing from the spirit and scope of the present invention, which is obvious to technicians familiar with the technical field without the need for creative work. All of the above should be regarded as the scope of the present invention.

[0034] It should be noted that, in the present invention, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A dual circular polarization metasurface array antenna structure, characterized in that: The array antenna structure is formed by a plurality of metasurface array antenna units; the metasurface array antenna units are composed of a radiation layer (1), a coupling layer (2) and a feeding layer (3) stacked in sequence from top to bottom; the upper surface of the radiation layer (1) is provided with a metasurface composed of a plurality of cut-corner triangle patterns; the upper surface of the coupling layer (2) is provided with a metal ground structure with gaps; the upper surface of the feeding layer (3) is provided with a U-shaped strip feed line, both ends of which are fed by coaxial probes, one of the ports is selected for feeding, and the other port is connected to a 50 ohm load to perform left-handed or right-handed circularly polarized radiation; and metallized isolation through holes are provided between each metasurface array antenna unit.

2. The dual circular polarization metasurface array antenna structure according to claim 1, characterized in that: The super surface structure of the radiation layer (1) is formed by rotating a square patch by 45 degrees to form a crisscross groove, and then cutting off four right angles, ultimately forming 8 cut-corner triangle patterns.

3. The dual circular polarization metasurface array antenna structure according to claim 1, characterized in that: The metal ground of the coupling layer (2) has a radial gap assembly, and the gap assembly is formed by rotating the gap along the positive direction of the Y axis from the center point around the Z axis toward the X axis and replicating it 4 times every 45 degrees.

4. A dual circular polarization metasurface array antenna structure according to claims 1 and 3, characterized in that: The U-shaped strip feeder of the feed layer (3) is provided with an impedance matching adjustment section at a position corresponding to the center of each slot, and the length and width of each adjustment section are changed to optimize the circular polarization axis ratio.

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