A dual-polarization tightly coupled ultra-wideband phased array antenna with high polarization isolation

Abstract

The present invention discloses a high polarization isolation dual-polarization tightly coupled ultra-wideband phased array antenna. It includes a dipole unit, a coaxial feed line, a metal reflective floor, a fishbone cross-shaped patch and a cross-shaped metal wall; the dipole unit includes a horizontal and two vertical dielectric substrates, and the vertical dielectric substrates are orthogonal to each other; two groups of coplanar and mutually perpendicular butterfly-shaped dipole units are printed on the lower surface of the horizontal dielectric substrate; a fishbone cross-shaped patch is embedded at the intersection of the ends of the dipole units, and there is a gap between the patch and the end of the dipole; a patch with an etched groove line is printed on one side of the vertical dielectric substrate; the patch is connected to the dipole; the microstrip line on the upper surface of the horizontal dielectric substrate is connected to the inner conductor of the coaxial feed line, and the dipole is connected to the outer conductor of the coaxial feed line; the fishbone cross-shaped patch is in contact with the cross-shaped metal wall. The present invention realizes high polarization isolation and low cross-polarization of the dual-polarization tightly coupled ultra-wideband phased array in a lower frequency band without the need for a complex feeding network.

Description

Technical Field

[0001] The invention belongs to the technical field of antennas, and in particular relates to a high polarization isolation dual-polarization tightly coupled ultra-wideband phased array antenna. Background Art

[0002] Since the fifth generation (5G) wireless communication technology has obvious advantages in high data transmission rate and low latency, the demand for it in wireless communication applications has shown an explosive growth trend. At present, the frequency bands used by 5G technology mainly include FR1 (Sub-6 GHz) and FR2 (mmWave). Although the millimeter wave can provide a wider spectrum, its path loss is large, and its ability to penetrate obstructions such as buildings is relatively weak. Compared with the millimeter wave frequency band, the Sub-6 GHz frequency band can meet the needs of long distance and wide coverage. Therefore, the Sub-6 GHz frequency band is favored by people. However, with the continuous expansion of the application field and performance requirements of 5G technology, new frequency bands such as 700MHz, 900MHz, and 2.6GHz have been allocated for the application of 5G technology in recent years, so the requirements for antenna design are getting higher and higher. On the one hand, the antenna is required to have characteristics such as ultra-wideband, dual polarization, and wide-angle scanning; on the other hand, the antenna is expected to be low in cost, light in weight, low in profile, good in mechanical strength, and simple to assemble. Therefore, an ultra-wideband dual-polarization antenna for new frequency bands of 5G technology, including 700MHz, has become an urgent need in engineering applications.

[0003] In order to alleviate multipath fading and increase system capacity and spectrum efficiency, dual-polarization massive MIMO (massive multiple-input multiple-output) technology has received widespread attention in 5G. At present, the main implementation forms of dual-polarization antenna units include patch antennas, Vivaldi antennas, metal waveguide antennas, and tightly coupled antenna arrays. However, for patch antennas, although their profile is low, their bandwidth is narrow and their gain is low; for Vivaldi antennas, although they have excellent bandwidth performance, their profile is high, their volume is bulky, and their integration is low. These shortcomings are also obvious, which greatly limits their application scope. For waveguide antennas, they are large in size, difficult to process, and costly, and are not suitable for lower frequency applications. In order to overcome the shortcomings of the above antennas, a new type of tightly coupled antenna array technology has been proposed, which achieves its ultra-wideband performance through the strong mutual coupling effect between antenna array elements, with a low profile and compact unit size. However, the structure of the tightly coupled antenna reported so far is relatively complex, and the feeding network usually requires a complex broadband balun with large losses. In addition, the array cost is high, the mechanical strength is weak, and the assembly is difficult. More importantly, the current dual-polarization tightly coupled ultra-wideband phased array has poor polarization isolation and high cross-polarization, and the wide-angle matching layer covering the top of the antenna increases the cost and complexity of the antenna. In summary, the development of low-cost and low-complexity dual-polarization phased arrays with both high polarization isolation and ultra-wideband performance has become a difficult problem that needs to be solved urgently, especially the development of Sub-6 GHz 5G dual-polarization phased arrays that include new frequency bands. The present invention is proposed to address these key issues. Summary of the invention

[0004] Technical problem: The purpose of the present invention is to provide a high polarization isolation dual-polarization tightly coupled ultra-wideband phased array antenna to solve the above technical problems. The structure of the present invention realizes high polarization isolation and low cross-polarization of the ultra-wideband dual-polarization tightly coupled phased array in a lower operating frequency band, has a simple structure, light weight, good mechanical strength, and simple feeding without a complex impedance matching network.

[0005] Technical solution: A high polarization isolation dual-polarization tightly coupled ultra-wideband phased array antenna of the present invention is composed of antenna units arranged in an array, each unit including: a horizontally placed butterfly dipole unit, a coaxial feeder placed vertically below the butterfly dipole unit, a horizontally placed metal reflection floor below the butterfly dipole unit, and a cross-shaped metal wall perpendicular to the metal reflection floor below the butterfly dipole unit; an SMA connector is connected to the coaxial feeder through a through hole on the metal reflection floor; the butterfly dipole unit includes a horizontally placed dielectric substrate and a vertically placed dielectric substrate; the lower surface of the horizontally placed dielectric substrate is connected to a metal patch with a slot line on one side of the vertically placed dielectric substrate; the microstrip line on the upper surface of the horizontally placed dielectric substrate is connected to the inner conductor of the coaxial feeder; the lower surface of the horizontally placed dielectric substrate is connected to the outer conductor of the coaxial feeder.

[0006] The horizontally placed dielectric substrate has a fishbone-shaped cross-shaped metal patch embedded between the intersections of the two groups of butterfly-shaped dipole ends on its lower surface.

[0007] There is a gap between the end of the lower surface of the horizontally placed dielectric substrate and the herringbone-shaped cross metal patch embedded therein.

[0008] The cross-shaped metal wall perpendicular to the metal reflective floor contacts the fishbone-shaped cross-shaped metal patch on the lower surface of the horizontal dielectric substrate.

[0009] A groove line is etched on the metal patch on one side of the vertically placed dielectric substrate.

[0010] The coaxial feed line is a standard 50Ω coaxial line, and the SMA connector is a standard 50Ω SMA connector.

[0011] The thickness of the cross-shaped metal wall located below the butterfly-shaped dipole unit and perpendicular to the metal reflective floor is 1.8 mm.

[0012] The horizontally placed dielectric substrate is Rogers RO4003, with a dielectric constant of 3.55 and a thickness of 0.813 mm; the vertically placed dielectric substrate is Rogers RO4003, with a dielectric constant of 3.55 and a thickness of 0.508 mm.

[0013] Beneficial effects: The high polarization isolation dual-polarization tightly coupled ultra-wideband phased array antenna of the present invention has the following advantages:

[0014] 1. The present invention discloses a high polarization isolation dual-polarization tightly coupled ultra-wideband phased array antenna. The array unit is composed of a horizontally placed butterfly dipole and a vertically placed metal patch with a slot line. The introduction of the vertical metal patch, on the one hand, widens the minimum operating frequency of the antenna without increasing the lateral size of the antenna, thereby realizing the miniaturization design of the antenna. On the other hand, a slot line is etched on the vertical metal patch to form a capacitive gap to offset the inductive reactance component of the dipole active input impedance at high frequency, thereby widening the upper limit operating frequency of the antenna, thereby realizing the ultra-wideband performance of the antenna.

[0015] 2. The input impedance of the array dipole unit within the working frequency band is close to 50Ω, and it can be directly fed by a standard 50Ω coaxial cable, which not only avoids the use of a complex impedance matching feeding network, but also reduces the loss caused by the feeding network and saves costs;

[0016] 3. The fishbone-shaped cross-shaped metal patch and the cross-shaped metal wall eliminate the common-mode resonance mode of the antenna within the working frequency band, alleviate the low-frequency loop mode that limits the antenna bandwidth, and achieve the ultra-wideband performance of the antenna;

[0017] 4. The vertically placed metal patch with slotted lines realizes the wide-angle scanning impedance matching of the antenna. Compared with the traditional thick dielectric matching layer covering the antenna array, the present invention realizes the low-cost, low-complexity and lightweight design of the antenna;

[0018] 5. The support of the cross-shaped metal wall also means that there is no need to fill the space between the antenna radiation surface and the metal reflective floor with supporting media or foam, which not only gives the antenna better mechanical strength but also greatly reduces the difficulty of assembling the antenna array. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of the three-dimensional structure of a high polarization isolation dual-polarization tightly coupled ultra-wideband phased array antenna according to an embodiment of the present invention;

[0020] Figure 2 is a schematic diagram of a 3D structure of an array unit according to an embodiment of the present invention;

[0021] Figure 3 is a top view of an array unit according to an embodiment of the present invention;

[0022] Figure 4 is a side view of an array unit according to an embodiment of the present invention;

[0023] Figure 5 The active voltage standing wave ratio of the E-plane, H-plane and D-plane of the unit in the embodiment of the present invention at the full-band port when the unit is side-fired and scanned at 45 degrees;

[0024] Figure 6 It is the full-band active voltage standing wave ratio of the full array and the central unit in the embodiment of the present invention when side-firing;

[0025] Figure 7 Polarization isolation of the cross-shaped metal wall loaded and unloaded by the unit in the embodiment of the present invention during side-shot and 45-degree scanning;

[0026] Figure 8 It is the main polarization and cross-polarization gain of the E surface of the unit in the embodiment of the present invention when the side is shot, 30 degree scanning, and 45 degree scanning;

[0027] Fig. 9 It is the main polarization and cross-polarization gain of the unit H plane in the embodiment of the present invention when the side is shot, 30 degree scanning, and 45 degree scanning;

[0028] Fig.10 It is the main polarization and cross-polarization gain of the D surface of the unit in the embodiment of the present invention when the side is shot, 30 degree scanning, and 45 degree scanning;

[0029] Markings in the figure: horizontal dipole unit 1, 50Ω coaxial feed line 2, metal reflection floor 3, cross-shaped metal wall 4, SMA connector 5, through hole 6, horizontally placed dielectric substrate 7, vertically placed dielectric substrate 8, slot line 9, vertical metal patch 10, microstrip line 11, herringbone-shaped cross-shaped metal patch 12, gap 13. DETAILED DESCRIPTION

[0030] In order to better understand the purpose, structure and function of the present invention, a high polarization isolation dual-polarization tightly coupled ultra-wideband phased array antenna of the present invention is further described in detail below with reference to the accompanying drawings.

[0031] Figure 1 Shown is a stereoscopic image of a high polarization isolation dual-polarization tightly coupled ultra-wideband phased array antenna, where the array size is 8×8.

[0032] Figures 2 to 4The figure shows a unit model diagram of a high polarization isolation dual-polarization tightly coupled ultra-wideband phased array antenna, comprising: a horizontally placed butterfly dipole unit 1, a vertically placed coaxial feed line 2 located below the butterfly dipole unit 1, a horizontally placed metal reflection floor 3 located below the butterfly dipole unit 1, and a cross-shaped metal wall 4 located below the butterfly dipole unit 1 and perpendicular to the metal reflection floor 3; an SMA connector 5 is connected to the coaxial feed line 2 through a through hole 6 on the metal reflection floor 3; the butterfly dipole unit 1 comprises a horizontally placed dielectric substrate 7 and a vertically placed dielectric substrate 8; the butterfly dipole unit 1 on the lower surface of the horizontally placed dielectric substrate 7 is connected to a metal patch 10 with a slot line 9 on one side of the vertically placed dielectric substrate 8; the microstrip line 11 on the upper surface of the horizontally placed dielectric substrate 7 is connected to the inner conductor of the coaxial feed line 2; the butterfly dipole unit 1 on the lower surface of the horizontally placed dielectric substrate 7 is connected to the outer conductor of the coaxial feed line 2. There is a gap 13 between the fishbone-shaped cross-shaped metal patch 12 and the end of the butterfly-shaped dipole unit 1 on the lower surface of the horizontally placed dielectric substrate 7 .

[0033] The present invention is different from the traditional dipole unit form. Instead, it is composed of a horizontally placed butterfly dipole and a vertically placed metal patch with a slot line. The introduction of the vertical metal patch widens the antenna's minimum operating frequency without increasing the lateral size, thereby realizing a miniaturized design of the antenna. A slot line is further etched on the vertical metal patch to form a capacitive gap to offset the inductive reactance component of the dipole active input impedance at high frequencies, thereby widening the antenna's maximum operating frequency and ultimately achieving the antenna's ultra-wideband performance.

[0034] The active input impedance of the dipole unit of the present invention is close to 50Ω in a wide operating frequency band, so a standard 50Ω coaxial feeder 2 can be directly used to feed the antenna, avoiding the use of a complex and lossy feeding network.

[0035] In order to achieve high polarization isolation, a cross-shaped metal wall 4 is introduced to shield the feeding part of the antenna, thereby greatly reducing the cross coupling between the polarizations of the antenna units.

[0036] In order to eliminate the common mode resonance mode appearing in the working frequency band of the antenna array, a cross-shaped metal wall 4 is introduced instead of adopting the conventional short-circuit via technology relying on multi-layer stacked PCB.

[0037] In order to alleviate the low-frequency loop mode that limits the bandwidth of the antenna array, a gap 13 is provided between the introduced fishbone-shaped cross-shaped metal patch 12 and the end of the butterfly-shaped dipole unit 1 on the lower surface of the horizontally placed dielectric substrate 7, thereby generating coupling.

[0038] The introduction of the cross-shaped metal wall 4 eliminates the need to fill any medium or foam as support between the horizontally placed dielectric substrate and the metal reflective floor 3, which is beneficial to reducing the manufacturing cost of the antenna.

[0039] In order to achieve wide-angle scanning impedance matching performance of the antenna, the antenna unit introduces a vertically placed metal patch 10 with a slot line 9, avoiding the use of a traditional covering layer as a wide-angle impedance matching layer, thereby greatly reducing the cost, weight and complexity of the antenna.

[0040] Figure 5 The figure shows the standing wave ratio characteristics corresponding to the ports of the E, D and H surfaces of the unit of this embodiment in the side-firing and 45-degree scanning states. It can be seen from the figure that when the standing wave ratio is required to be less than 3.5, the dipole of the present invention has an impedance bandwidth of 4.1:1 (0.69-2.88GHz) within the 45-degree scanning range.

[0041] Figure 6 The figure shows the standing wave ratio characteristics corresponding to the port of this embodiment in the side-firing state. It can be seen from the figure that in the frequency band of 0.69-2.88 GHz, the test standing wave ratio of the central unit of the 8×8 array composed of dipole units of the present invention is less than 3, and the test standing wave ratio of the whole array is less than 2.

[0042] Figure 7 The figure shows the comparison of polarization isolation of the dipole unit of this embodiment with and without the cross-shaped metal wall in the case of side-firing in the frequency band of 0.69-2.88 GHz. It can be seen from the figure that when the cross-shaped metal wall is loaded, the polarization isolation of the antenna unit in side-firing is higher than 45 dB, and the polarization isolation is higher than 35 dB when scanning to 45°, which are 21 dB and 15 dB higher than when the cross-shaped metal wall is not loaded.

[0043] Figure 8 The figure shows the main polarization and cross polarization of the dipole unit of this embodiment when scanning at 0, 30 and 45 degrees on the E plane in the frequency band of 0.69-2.88 GHz. It can be seen from the figure that the phased array antenna unit has a cross polarization characteristic of less than -40 dB when scanning to 45 degrees.

[0044] Fig. 9 The figure shows the main polarization and cross polarization of the dipole unit of this embodiment when the H plane is scanned at 0, 30 and 45 degrees in the frequency band of 0.69-2.88 GHz. It can be seen from the figure that the phased array antenna unit has a cross polarization characteristic of less than -40 dB when scanning to 45 degrees.

[0045] Fig.10The figure shows the main polarization and cross polarization of the dipole unit of this embodiment when scanning at 0, 30 and 45 degrees on the D plane in the frequency band of 0.69-2.88 GHz. It can be seen from the figure that the phased array antenna unit has a cross polarization characteristic of less than -12 dB when scanning to 45 degrees.

[0046] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0047] The terms "including", "having", "introducing" and any variations thereof in the embodiments of the present application are intended to cover non-exclusive inclusions. For example, a process, method, device, product or equipment including a series of steps or modules is not limited to the listed steps or modules, but may optionally include steps or modules not listed, or may optionally include other steps or modules inherent to these processes, methods, products or equipment.

[0048] It is to be understood that the present invention is described by some embodiments, and it is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope of protection of the present invention.

Claims

1. A high polarization isolation dual-polarization tightly coupled ultra-wideband phased array antenna, characterized in that: The phased array antenna is composed of antenna units arranged in an array, each unit comprising: a horizontally placed butterfly-shaped dipole unit (1), a coaxial feeder (2) vertically placed below the butterfly-shaped dipole unit (1), a horizontally placed metal reflection floor (3) below the butterfly-shaped dipole unit (1), and a cross-shaped metal wall (4) located below the butterfly-shaped dipole unit (1) and perpendicular to the metal reflection floor (3); SMA The connector (5) passes through a through hole (6) on the metal reflective floor (3) and is connected to the coaxial feed line (2); the butterfly dipole unit (1) comprises a horizontally placed dielectric substrate (7) and a vertically placed dielectric substrate (8); the lower surface of the horizontally placed dielectric substrate (7) is connected to a metal patch (10) having a slot line (9) on one side of the vertically placed dielectric substrate (8); the microstrip line (11) on the upper surface of the horizontally placed dielectric substrate (7) is connected to the inner conductor of the coaxial feed line (2); the lower surface of the horizontally placed dielectric substrate (7) is connected to the outer conductor of the coaxial feed line (2); The horizontally placed dielectric substrate (7) has a fishbone-shaped cross-shaped metal patch (12) embedded between the intersections of the two groups of butterfly-shaped dipole ends on its lower surface; There is a gap (13) between the end of the lower surface of the horizontally placed dielectric substrate (7) and the herringbone-shaped cross-shaped metal patch (12) embedded therein.

2. The high polarization isolation dual-polarization tightly coupled ultra-wideband phased array antenna according to claim 1, characterized in that: The cross-shaped metal wall (4) perpendicular to the metal reflective floor (3) is in contact with a fishbone-shaped cross-shaped metal patch (12) on the lower surface of the horizontal dielectric substrate (7).

3. The high polarization isolation dual-polarization tightly coupled ultra-wideband phased array antenna according to claim 1, characterized in that: A metal patch (10) on one side of the vertically placed dielectric substrate (8) is etched with a groove line (9).

4. The high polarization isolation dual-polarization tightly coupled ultra-wideband phased array antenna according to claim 1, characterized in that: The coaxial feed line (2) is a standard 50 Ω coaxial line, and the SMA connector (5) is a standard 50 Ω SMA connector.

5. The high polarization isolation dual-polarization tightly coupled ultra-wideband phased array antenna according to claim 1, characterized in that: The thickness of the cross-shaped metal wall (4) located below the butterfly-shaped dipole unit (1) and perpendicular to the metal reflective floor (3) is 1.8 mm.

6. The high polarization isolation dual-polarization tightly coupled ultra-wideband phased array antenna according to claim 1, characterized in that: The horizontally placed dielectric substrate (7) is Rogers RO4003, with a dielectric constant of 3.55 and a thickness of 0.813 mm; the vertically placed dielectric substrate (8) is Rogers RO4003, with a dielectric constant of 3.55 and a thickness of 0.508 mm.

Images