Ultra-low axial ratio dual circularly polarized phased array antenna loaded with solar cell

Abstract

The invention discloses an ultra-low axial ratio dual circularly polarized phased-array antenna loaded with solar cells, the ultra-low axial ratio dual circularly polarized phased-array antenna loaded with solar cells comprises 16 * 16 sub-arrays, each sub-array comprises five layers of dielectric plates, circularly polarized antenna units are printed on different layers of the multilayer dielectric plates, and the circularly polarized antenna units are printed on different layers of the multilayer dielectric plates. The antenna is provided with a metasurface, two sets of power dividing feed networks with phase shift output, and metalized via holes which pass through different layers of dielectric plates and are used for feeding and shielding. And a solar cell sheet is bonded on the metasurface grid on the uppermost layer of the dielectric plate. According to the overall scheme, the integrated design with the solar cell is realized while the performance of the circularly polarized phased array is improved.

Description

Technical Field

[0001] The present invention belongs to the field of phased array antennas, and in particular relates to an ultra-low axial ratio dual circularly polarized phased array antenna loaded with solar cells. Background Art

[0002] For many communication systems, including satellite communications, the communication objects are no longer limited to fixed targets. As the target moves, the polarization direction of the antenna may change. Linearly polarized antennas can only receive electromagnetic waves with co-directional polarization. Non-co-directional polarization will cause polarization mismatch, so they have a significant disadvantage in high-speed mobile communications. Circularly polarized antennas are insensitive to the position and posture of the target, making them a better choice for mobile communications. In addition, circularly polarized antennas have the following characteristics:

[0003] (1) Orthogonality of rotation direction;

[0004] (2) When the incident target is a symmetrical target, the direction of rotation of the electromagnetic wave is reversed when it is reflected. This can suppress rain and fog interference and resist multipath interference;

[0005] (3) After the circularly polarized wave passes through the Faraday rotation caused by the ionosphere, its circular polarization characteristics and rotation direction remain unchanged, which can avoid polarization mismatch.

[0006] With the development of modern communication systems and the increasing demand for communications, the development of high-speed, high-capacity wireless communication systems is becoming increasingly important. As a crucial component of communication systems, increasing antenna bandwidth can enhance channel capacity and improve signal transmission rates. Furthermore, wideband antennas can distribute the available operating frequency bandwidth on a single antenna, enabling multiple transmit and receive channels. Therefore, using wideband antennas can reduce the number of devices, lower costs, and reduce system size. Furthermore, wideband antennas can temporally separate received multipath signals, providing a certain degree of robustness against multipath interference.

[0007] Among them, the axial ratio is an important indicator to measure the polarization purity of circularly polarized antennas. Therefore, optimizing the axial ratio indicator of circularly polarized antennas plays an important role in reducing antenna polarization mismatch and improving antenna reception performance. At present, common circularly polarized antennas maintain a radiation axial ratio of less than 3dB within the operating frequency band, but some extreme cases, such as large-aperture satellite communication arrays, have higher requirements for the axial ratio. For example, the axial ratio in the main radiation direction is required to be less than 0.75dB. However, conventional circularly polarized antenna units are either unable to achieve such a low axial ratio or can only achieve this performance within an extremely narrow bandwidth. In addition, planar microstrip circularly polarized antennas are limited by their own characteristics and have a narrow bandwidth. It is even more difficult to achieve dual circularly polarized radiation under the above conditions. Therefore, it is very necessary to design a broadband, low-axial-ratio dual circularly polarized phased array antenna.

[0008] Furthermore, in remote areas like the wild, where electricity is inconvenient, solar panels can be used to collect solar energy and power the array. Compared to using separate solar panels, integrating solar cells and phased array antennas without compromising antenna radiation performance offers significant advantages in terms of size, weight, and cost. Traditional solar cell and antenna integration methods include placing the antenna above the solar cell or interleaving the solar cell and antenna. With the first approach, the antenna obstructs the solar cell, reducing energy efficiency. With the second approach, the antenna can only be mounted vertically and slender, limiting the antenna's form. Furthermore, the solar cells significantly impact the mutual coupling between the antennas and their radiation characteristics. In this design, the solar cells are integrated above the antenna, eliminating light obstruction. Furthermore, the solar cells can be treated as metal sheets, effectively preventing any impact on the antenna's radiation characteristics.

[0009] Combining the above advantages, the ultra-low axial ratio dual circularly polarized phased array antenna loaded with solar cells has high research value and application prospects. At the same time, the design is also very difficult. This design can take into account the above multiple technical characteristics and is highly innovative. Summary of the Invention

[0010] This invention proposes an ultra-low axial ratio dual circularly polarized phased array antenna loaded with solar cells. Through a multi-layer design, the feed network is integrated into several layers of printed circuit boards on the ground, reducing solution complexity, eliminating the need for a loading bridge, and lowering costs. Furthermore, the antenna unit utilizes a printed circuit board (PCB), with the top layer consisting of a square metal grid. Square solar cells are bonded to this top layer, integrating power supply and radio frequency (RF) control.

[0011] The technical solution to implement the present invention is: an ultra-low axial ratio dual circularly polarized phased array antenna loaded with solar cells, including 16*16 subarrays and solar cells, each subarray including a 2*2 sequential rotation structure, and each sequential rotation structure including 2*2 broadband dual circularly polarized units arranged in sequence.

[0012] The subarray includes a right-hand circularly polarized feed network, a left-hand circularly polarized feed network, a first metal floor, a second metal floor, a metal frame, a five-layer dielectric plate, 16 circularly polarized radiating elements, 16 groups of 4×4 metasurfaces and four types of metalized vias.

[0013] The five layers of dielectric plates are arranged from top to bottom, namely the first dielectric plate, the second dielectric plate, the third dielectric plate, the fourth dielectric plate, and the fifth dielectric plate. Sixteen circularly polarized radiation units are printed on the upper surface of the second dielectric plate, 16 groups of 4×4 metasurfaces are printed on the upper surface of the first dielectric plate, a right-handed circularly polarized feeding network is printed on the upper surface of the fourth dielectric plate, and a left-handed circularly polarized feeding network is printed on the lower surface of the fifth dielectric plate. The first metal floor is printed on the upper surface of the third dielectric plate, and the second metal floor is printed on the upper surface of the fifth dielectric plate. Metallized vias are used to connect metals of different layers.

[0014] Compared with the prior art, the present invention has the following significant advantages:

[0015] (1) The present invention adopts a sequentially rotated structure of 2*2 units as the subarray basis. This structure can meet the requirements of orthogonal distribution of circular polarization, and the coupling between units is small. Under the same feeding requirements for circular polarization, this design can ensure the distribution of two orthogonal currents with stable amplitude and phase in the antenna unit within a wide bandwidth, thereby achieving the ultra-low axial ratio characteristics of antenna radiation within a wide bandwidth, and thus making the antenna unit have stable radiation gain.

[0016] (2) The dual circular polarization unit used in the present invention is a double-layer structure, including a main radiation patch and a loaded metasurface. The metasurface is used to broaden the working bandwidth. In addition, the sequential rotation structure also has broadband characteristics. The superposition of the two layers of technology ultimately realizes the broadband characteristics of the entire array.

[0017] (3) The present invention adopts large-spacing subarray synthesis technology. Each subarray includes 4*4 dual circular polarization units. This structure can reduce the number of channels and effectively reduce costs and system complexity.

[0018] (4) The present invention can have dual circular polarization characteristics and can meet the needs of different usage scenarios.

[0019] (5) The broadband low axial ratio dual circularly polarized phased array antenna designed in the present invention adopts a printed circuit board structure, which is easy to process, has a high degree of integration, and is easy to conformally design according to the platform structure.

[0020] (6) The phased array antenna designed in the present invention can be integrated with solar cells, and the solar cells have little effect on the radiation characteristics and standing wave characteristics of the antenna. This design can lay a technical foundation for subsequent self-powered designs. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the subarray.

[0022] Figure 2 It is a schematic diagram of the sub-array stacking.

[0023] Figure 3 Schematic diagram of circularly polarized radiation unit

[0024] Figure 4 is a schematic diagram of the super surface layer.

[0025] Figure 5 This is a schematic diagram of the first metal floor.

[0026] Figure 6 This is a schematic diagram of the right-hand circularly polarized feeding network.

[0027] Figure 7 This is a schematic diagram of the left-hand circularly polarized feeding network.

[0028] Figure 8 This is a schematic diagram of the antenna subarray structure framework.

[0029] Figure 9 It is a schematic diagram of the solar cell structure.

[0030] Figure 10 It is the simulated standing wave diagram of the phased array antenna.

[0031] Figure 11 This is the simulated axial ratio diagram of the phased array antenna.

[0032] Figure 12 It is the simulated gain diagram of the phased array antenna.

[0033] Figure 13 It is the simulated beam scanning characteristic diagram of the phased array antenna. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0036] In addition, the terms "first," "second," and so on, used in this disclosure are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features being referenced. Thus, features specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this disclosure, "plurality" means at least two, such as two or three, unless otherwise specifically defined.

[0037] In the present invention, unless otherwise specified or limited, the terms "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can refer to fixed connection, detachable connection, or integration; "connection" can refer to mechanical connection or electrical connection. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0038] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in this field can implement it. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0039] The following will further introduce the specific implementation methods, as well as the technical difficulties and inventive points of this invention in combination with this design example.

[0040] The ultra-low axial ratio dual circular polarization phased array antenna loaded with solar cells of the present invention comprises 16*16 sub-arrays and solar cells, such as Figure 1 As shown, each sub-array includes 2*2 sequential rotation structures 1, and each sequential rotation structure 1 includes 2*2 broadband dual circular polarization units 2 that are sequentially rotated and arranged.

[0041] like Figure 2 As shown, the subarray includes a five-layer dielectric plate, 16 circularly polarized radiating units 3, 16 groups of 4×4 metasurfaces 4, two sets of 1-to-16 broadband phase-shift power splitter feeding networks (respectively, a right-handed circularly polarized feeding network 5 and a left-handed circularly polarized feeding network 6), a first metal floor 7, a second metal floor 8, four types of metalized vias and a metal frame 9.

[0042] The five-layer dielectric board is made of RA300G material with a dielectric constant of 2.95 and a loss tangent of 0.0015. Adjacent dielectric boards are bonded with prepregs and finally pressed together using a multi-layer board lamination technology.

[0043] The five layers of dielectric plates are arranged in sequence from top to bottom, namely the first dielectric plate, the second dielectric plate, the third dielectric plate, the fourth dielectric plate, and the fifth dielectric plate. Sixteen circularly polarized radiation units 3 are printed on the upper surface of the second dielectric plate, 16 groups of 4×4 metasurfaces 4 are printed on the upper surface of the first dielectric plate, a set of 1-to-16 broadband phase-shifted power splitter feeding networks are printed on the upper surface of the fourth dielectric plate and the lower surface of the fifth dielectric plate, respectively, which are a right-handed circularly polarized feeding network 5 and a left-handed circularly polarized feeding network 6. A first metal floor 7 is printed on the upper surface of the third dielectric plate, and a second metal floor 8 is printed on the upper surface of the fifth dielectric plate. The metallized vias are divided into four groups to connect metals of different layers.

[0044] like Figure 3 As shown, the 16 circularly polarized radiating elements 3 are grouped into groups of four. Within each group, the four circularly polarized radiating elements 3 are spaced apart and rotated by 0°, 90°, 180°, and 270°, respectively, to form a 2×2 sequentially rotated structure 1. The four sequentially rotated structures 1 form a subarray, i.e., a subarray comprising 4×4 antenna elements. The patch is a square truncated patch, fed in orthogonal directions to achieve circular polarization of different handednesses.

[0045] like Figure 4 As shown, the 16 groups of 4×4 metasurfaces 4 are identical, consisting of 16 square metal patches, each corresponding to a circularly polarized radiating element 3, with the horizontal center points aligned. Some areas are cut to avoid fixing screw holes.

[0046] Traditional microstrip patch antennas have relatively narrow bandwidths, especially dual circularly polarized microstrip patch antennas implemented on a single patch. This invention utilizes a metasurface combined with a dual circularly polarized radiating patch to achieve two adjacent resonant frequencies. These close proximity of frequencies enables broadband dual circularly polarized radiation.

[0047] like Figure 6 and Figure 7 As shown, the two sets of 1-to-16 broadband phase-shifted power splitter feeding networks have a right-handed circularly polarized feeding network 5 in a stripline format located on the upper surface of the fourth dielectric plate, and a left-handed circularly polarized feeding network 6 in a microstrip format located on the lower surface of the fifth dielectric plate. In terms of output characteristics, the 16 output ports of the two power splitter feeding networks can be divided into four groups. The four output ports in each group output currents of the same amplitude with phases shifted by ±90° (+90° for left-hand rotation and -90° for right-hand rotation), and the outputs of each group are consistent.

[0048] It is difficult to achieve an extremely low circular polarization axial ratio by relying solely on the structure of a dual circularly polarized microstrip patch loaded metasurface, and its axial ratio bandwidth is not wide. By utilizing the above two sets of feeding networks with different phase outputs, on the basis of the original circular polarization characteristics and according to the principle of circular polarization synthesis, a lower axial ratio and a wider circular polarization axial ratio bandwidth are achieved.

[0049] like Figure 5 As shown, the two metal floors are: the first metal floor 7 is a metal coating printed on the upper surface of the third dielectric plate, and the second metal floor 8 is a metal coating printed on the upper surface of the fifth dielectric plate. The metal floor is perforated to ensure the passage of the coaxial cable.

[0050] The presence of two layers of metal flooring allows the two sets of feed networks to be isolated from the upper radiation layer, preventing them from affecting each other and avoiding the impact of the feed network layer on the overall radiation performance.

[0051] There are 4 types of metalized vias. There are 16 metalized vias of the first type, which are used as feeding probes to connect the right-hand circularly polarized feeding network 5 and the 16 circularly polarized radiating units 3 on the upper surface of the fourth dielectric plate. The probe can transmit the output energy of the right-hand feeding network (including amplitude and phase characteristics) to the upper radiation patch. There are 16 metalized vias of the second type, which are also used as feeding probes to connect the left-hand circularly polarized feeding network 6 and the 16 circularly polarized radiating units 3 on the lower surface of the fifth dielectric plate. The probe can transmit the output energy of the left-hand feeding network (including amplitude and phase characteristics) to the upper radiation patch. phase characteristics) are transmitted to the upper radiation patch; the third type of metallized vias are divided into 16 groups, each group includes two parallel rows of metallized vias located near the first type of metallized vias, and connected to the first metal floor 7 and the second metal floor 8. The metallized vias can realize the transition from the stripline to the coaxial feeding probe; the fourth type of metallized vias are divided into 16 groups, each group includes two parallel rows of metallized vias located near the second type of metallized vias, and connected to the first metal floor 7 and the lower surface of the fifth dielectric plate. The metallized vias can realize the transition from the microstrip line to the coaxial feeding probe.

[0052] The structural components used in this example are as follows Figure 8 As shown, the metal frame 9 is bonded to the metal pads on the bottom layer of the sub-array for fixation. A notch is opened in the middle crossbeam of the metal frame 9 to ensure the passage of the feeder and minimize the impact on its output. At the same time, a screw hole design is opened to ensure the subsequent fixing of the connector flange.

[0053] The solar cells loaded in the sub-array of this example are as follows Figure 9 As shown in the figure, it consists of three layers: a silver electrode, a silicon layer, and an aluminum electrode, from top to bottom. The top layer of the printed circuit board contains 16 groups of 4×4 square metasurface 4 grids, a metal-plated layer. Silicon-based solar cells are bonded to the metasurface 4 using conductive adhesive. The size of the solar cells is slightly smaller than that of the metasurface 4 grids.

[0054] Reference Figure 10-13 , which are the electrical performance parameters of a low-axial-ratio dual-circularly-polarized antenna element simulated using the commercial electromagnetic simulation software ANSYS Electronics Desktop. Within the frequency band, the standing wave (SWR) in both operating modes with different rotational directions is less than 1.5, the axial ratio is less than 1, and the gain is greater than 42.2dB. Furthermore, at the center frequency of 3.8GHz, the beam scanning characteristics of the antenna were simulated at a 16x16 scale, revealing a beam scanning range of ±5 degrees.

Claims

1. An ultra-low axial ratio dual circularly polarized phased array antenna loaded with solar cells, characterized by: The invention comprises 16*16 sub-arrays and solar cell sheets, each sub-array comprises 2*2 sequential rotation structures (1), and each sequential rotation structure (1) comprises 2*2 broadband dual circular polarization units (2) that are sequentially arranged and rotated.

2. The ultra-low axial ratio dual circularly polarized phased array antenna loaded with solar cells according to claim 1, characterized in that: The subarray includes a right-hand circularly polarized feeding network (5), a left-hand circularly polarized feeding network (6), a first metal floor (7), a second metal floor (8), a metal frame (9), a five-layer dielectric plate, 16 circularly polarized radiating elements (3), 16 groups of 4×4 metasurfaces (4), and four types of metalized vias; The five dielectric plates are arranged in sequence from top to bottom, namely a first dielectric plate, a second dielectric plate, a third dielectric plate, a fourth dielectric plate, and a fifth dielectric plate; 16 circularly polarized radiation units (3) are printed on the upper surface of the second dielectric plate; 16 groups of 4×4 metasurfaces (4) are printed on the upper surface of the first dielectric plate; a right-handed circularly polarized feeding network (5) is printed on the upper surface of the fourth dielectric plate; a left-handed circularly polarized feeding network (6) is printed on the lower surface of the fifth dielectric plate; a first metal floor (7) is printed on the upper surface of the third dielectric plate; a second metal floor (8) is printed on the upper surface of the fifth dielectric plate; and metallized vias are used to connect metals of different layers.

3. The ultra-low axial ratio dual circularly polarized phased array antenna loaded with solar cells according to claim 2, characterized in that: The five-layer dielectric board is made of RA300G material with a dielectric constant of 2.95 and a loss tangent of 0.0015. Adjacent dielectric boards are bonded with prepreg and pressed together using multi-layer board lamination technology.

4. The ultra-low axial ratio dual circularly polarized phased array antenna loaded with solar cells according to claim 2, characterized in that: Among the 16 circularly polarized radiation units (3), every 4 are divided into a group, and the four circularly polarized radiation units (3) in the same group are placed at intervals and rotated by 0°, 90°, 180° and 270° respectively to form a 2×2 sequential rotation structure (1). The four sequential rotation structures (1) constitute a subarray, that is, the subarray contains 4×4 antenna units; the patch shape is a square truncated patch, which is fed in orthogonal directions to achieve circular polarization of different rotation directions.

5. The ultra-low axial ratio dual circularly polarized phased array antenna loaded with solar cells according to claim 4, characterized in that: Among the 16 groups of 4×4 metasurfaces (4), the metasurfaces (4) in each group are completely identical, consisting of 16 square metal patches, each corresponding to a circularly polarized radiation unit (3), and having the same horizontal center point; by combining the metasurface with the dual circularly polarized radiation patch, two adjacent resonant frequency points are realized, and the two frequency points are close to each other to realize broadband dual circularly polarized radiation.

6. The ultra-low axial ratio dual circularly polarized phased array antenna loaded with solar cells according to claim 2, characterized in that: The right-hand circular polarization feeding network (5) and the left-hand circular polarization feeding network (6) are both 1-to-16 broadband phase-shifted power splitter feeding networks. In terms of output characteristics, the 16 output ports of the two power splitter feeding networks are divided into 4 groups, and the 4 output ports of each group output currents with the same amplitude and phase difference of ±90°, that is, left-hand rotation +90° and right-hand rotation -90°, and the outputs of each group are consistent.

7. The ultra-low axial ratio dual circularly polarized phased array antenna loaded with solar cells according to claim 2, characterized in that: There are four types of metalized vias. The first type of metalized vias has 16 metalized vias, which are used as feeding probes to connect the right-hand circularly polarized feeding network (5) and 16 circularly polarized radiating units (3) on the upper surface of the fourth dielectric plate. The probe can transmit the output energy of the right-hand feeding network to the upper radiation patch. The second type of metalized vias has 16 metalized vias, which are also used as feeding probes to connect the left-hand circularly polarized feeding network (6) and 16 circularly polarized radiating units (3) on the lower surface of the fifth dielectric plate. The probe can transmit the output energy of the left-hand feeding network to the upper radiation patch. The third type of metallized vias are divided into 16 groups, each group including two parallel rows of metallized vias located near the first type of metallized vias and connecting the first metal floor (7) and the second metal floor (8), and the metallized vias can realize the transition from the strip line to the coaxial feeding probe; the fourth type of metallized vias are divided into 16 groups, each group including two parallel rows of metallized vias located near the second type of metallized vias and connecting the first metal floor (7) and the lower surface of the fifth dielectric plate, and the metallized vias can realize the transition from the microstrip line to the coaxial feeding probe.

8. The ultra-low axial ratio dual circularly polarized phased array antenna loaded with solar cells according to claim 2, characterized in that: The metal frame (9) is bonded to the metal pad of the bottom layer of the sub-array for fixation. A notch is opened in the middle crossbeam of the metal frame (9) to ensure the passage of the feeder and to avoid the influence on its output as much as possible. At the same time, a screw hole design is opened to ensure the flange of the subsequent fixed connector.

9. The ultra-low axial ratio dual circularly polarized phased array antenna loaded with solar cells according to claim 2, characterized in that: The solar cell is composed of three layers, which are a silver electrode, a silicon layer, and an aluminum electrode from top to bottom. The top layer of the printed circuit board is composed of 16 groups of 4×4 square supersurface (4) grids, which are metal-plated layers. The silicon-based solar cell is bonded to the supersurface (4) with conductive glue. The size of the solar cell is smaller than the size of the supersurface (4) grid.

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