Low-profile wide-beam tri-polarized antenna

Abstract

The low-profile wide-beam tri-polarized antenna comprises a dielectric substrate, and a square radiation patch, a circular radiation patch, an annular parasitic patch and a rectangular parasitic patch are printed on the upper surface of the dielectric substrate; a metal floor is arranged on the lower surface of the dielectric substrate; the first metal probe and the second metal probe feed the square radiation patch. The third metal probe feeds power to the circular radiation patch. The second metal hole is connected with the rectangular parasitic patch and the metal floor, and the first metal hole is connected with the annular parasitic patch and the metal floor. Metal electric walls are replaced by the metal through holes and the parasitic patches, so that the profile of the antenna is reduced. The antenna is applied to a tri-polarized antenna. And meanwhile, a planar monopole antenna with a lower height is adopted when the tri-polarized antenna is designed, so that the beam width of the tri-polarized antenna is increased, the profile of the tri-polarized antenna is reduced, the size of the tri-polarized antenna is reduced, the cost of the tri-polarized antenna is reduced, and the efficiency of the tri-polarized antenna is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of tri-polarized antennas, and in particular relates to a low-profile wide-beam tri-polarized antenna. Background Art

[0002] With the growing demand for wireless communications, the traditional single linear polarization antenna is limited in further application due to the existence of channel fading, limited channel capacity and other shortcomings. Design and Research of Triple Polarization Conformal Microstrip Antenna [D]. Tsinghua University, 2009, proposed a conformal tri-polarization antenna unit. The thickness of the antenna is less than 0.08λ, and its vertical polarization antenna uses the top loading method to reduce the profile height, and its working bandwidth is 7.6%. The antenna horizontal dual polarization uses microstrip coupling feeding to improve the isolation between the three ports of the antenna. The isolation between the three ports is better than 16dB, and the three different polarization modes can work independently.

[0003] Research on tri-polarized metal via-loaded slot antenna [D]. Nanjing University of Posts and Telecommunications, 2016 A tri-polarized antenna consisting of three mutually orthogonal slot antennas is proposed. The tri-polarized antenna has a symmetrical structure, an operating bandwidth of 70MHz, and a maximum isolation between the antenna ports of -25.1dB. In the omnidirectional direction of the E plane, the difference between the main polarization and the cross polarization is greater than 13dB, and the difference between the main polarization and the cross polarization of the single-chip antenna is greater than 16.5dB. However, the tri-polarized antenna designed is composed of three mutually orthogonal slot antennas, which results in a large size of the antenna, a high profile, a large volume, and difficulty in integration with other circuits, limiting the application of the tri-polarized antenna.

[0004] In order to reduce the size of the tri-polarized antenna and reduce the antenna profile, Y. Wang, D. Piao and J. Zuo, "AWide-Angle and Fully Polarimetric Retrodirective Array Based on Tri-Polarized Antennas With Pattern Complementation," in IEEE Transactions on Antennas and Propagation, vol. 70, no. 6, pp. 4518-4525, June 2022. proposed a tri-polarized antenna loaded with parasitic patches. The parasitic circular patch produces a monopole-like directivity pattern. The square patch has two mutually orthogonal TM11 modes. The antenna thickness is 0.039λ, the operating bandwidth is 4%, and the port isolation is greater than 15dB. Although the profile of this antenna is already very low, it still uses a double-layer dielectric plate and multi-order metal holes. The structure of the antenna is not simple, and the complex structure greatly increases the processing cost of the antenna. In addition, the tri-polarized antenna still uses a narrow-beam microstrip antenna, which is difficult to meet the needs of wide-angle scanning.

[0005] In summary, the disadvantages of the existing three-polarization antenna technology are:

[0006] (1) The antenna has a high profile and large size, making it difficult to miniaturize, difficult to process, and high in cost;

[0007] (2) The antenna beam is narrow and cannot meet the requirements of wide-angle scanning. The antenna scanning efficiency is low and the application scenarios are limited.

[0008] (3) Although the current wide-beam antenna technology is very mature, most wide-beam designs use asymmetric structures to widen the antenna beam, while the design of a tri-polarized antenna requires a symmetrical structure, which makes it difficult to apply wide-beam antenna technology to tri-polarized antennas. In addition, most existing wide-beam antennas can only widen one surface (E or H surface) of the antenna, which also limits the application scenarios of wide-beam antennas. Summary of the invention

[0009] In order to overcome the deficiencies of the above-mentioned prior art, the purpose of the present invention is to provide a low-profile wide-beam tri-polarized antenna. Based on the principle of pattern superposition, the pattern generated by the centrally symmetrical metal electric wall is superimposed with the pattern of the main radiation patch, so that the beam of the microstrip antenna is effectively widened. In the design, metal through holes and parasitic patches are used to replace the metal electric wall, thereby reducing the profile of the antenna. At the same time, when it is applied to the tri-polarized antenna, a planar monopole antenna with a lower height is used, which increases the beam width of the tri-polarized antenna while reducing the profile of the tri-polarized antenna, reduces the size of the tri-polarized antenna, reduces the cost of the tri-polarized antenna, improves the efficiency of the tri-polarized antenna, and increases the application scenarios of the tri-polarized antenna.

[0010] In order to achieve the above object, the technical solution adopted by the present invention is:

[0011] A low-profile wide-beam tri-polarized antenna comprises a dielectric substrate, wherein a square radiation patch, a circular radiation patch, a circular parasitic patch and a rectangular parasitic patch are printed on the upper surface of the dielectric substrate; and a metal floor is arranged on the lower surface;

[0012] Metal probe 1 and metal probe 2 are used to feed the square radiation patch; metal probe 3 is used to feed the circular radiation patch; metal hole 2 connects the rectangular parasitic patch and the metal floor, and metal hole 1 connects the circular parasitic patch and the metal floor.

[0013] The square radiation patch is located at the center of the upper layer of the dielectric substrate, and a circular hole is dug out in the middle to place the circular radiation patch and the annular parasitic patch.

[0014] The center of the circular radiation patch is located at the center of the upper layer of the dielectric substrate, is arranged concentrically with the annular parasitic patch and the circular radiation patch, and has a gap with the inner ring wall of the annular parasitic patch.

[0015] There are four rectangular parasitic patches, which are located around the square radiation patch with a certain distance, and are symmetrically arranged along the center of the square radiation patch.

[0016] The metal probe 1 is set at a certain distance from the center of the square radiation patch along the x direction, the metal probe 2 is set at a certain distance from the center of the square radiation patch along the y direction, the distances between the metal probe 1 and the metal probe 2 and the center of the square radiation patch are equal, the center of the metal probe 3 is located at the center of the dielectric substrate, and the x direction and the y direction are the length and width directions of the square radiation patch respectively.

[0017] Metal probe 1, metal probe 2 and metal probe 3 correspond to three different polarizations when excited;

[0018] When the metal probe 1 is excited alone, the antenna is an x-polarized antenna, when the metal probe 2 is excited alone, the antenna is a y-polarized antenna, and when the metal probe 3 is excited alone, the antenna is a z-polarized antenna.

[0019] There are two metal holes in total, which form an angle of θ=45° with the x direction. The two metal holes are symmetrically arranged with the metal probe three as the center.

[0020] The metal hole 2 is tangent to the inner side of the rectangular parasitic patch. The inner side of the rectangular parasitic patch is defined as the side close to the square radiation patch. There are 12 metal holes 2 in total, which are divided into 4 groups, with 3 holes in each group.

[0021] Each group of metal holes 2 connects a rectangular parasitic patch and a metal floor, and the remaining three groups are obtained by rotating one group along the center of the dielectric substrate 11 by 90°, 180°, and 270° in sequence.

[0022] In a group of metal holes 2, the tangent point between the middle metal hole 2 and the rectangular parasitic patch is located at the midpoint of the inner long side of the rectangular parasitic patch, and the other two metal holes are arranged equidistantly along both sides of the middle metal hole 2; the metal hole 2 and the rectangular parasitic patch together play a role in widening the beam width of the microstrip antenna.

[0023] Metal holes three are arranged at the four corners of the square radiation patch. There are four metal holes three in total. The metal holes three are arranged at a certain distance from the four corners of the square radiation patch, so as to adjust the impedance matching of the square radiation patch.

[0024] Beneficial effects of the present invention:

[0025] The present invention combines a tri-polarized antenna and a wide-beam antenna for the first time, designs a tri-polarized antenna with a wide-beam characteristic, and the present invention performs a low-profile design on the antenna when designing the tri-polarized antenna and the wide-beam antenna, thereby greatly reducing the implementation cost of the antenna;

[0026] The present invention adopts a method of staggered folded electric wall to widen the beam of the microstrip antenna, that is, a pair of parasitic patches and metal hole 2 with a spatial position difference of 180°; the staggered structure designed by the present invention enables the beams of both surfaces of the antenna to be widened, and this method can widen the beam of the microstrip antenna while reducing the cross-section of the antenna;

[0027] Most tri-polarized antennas use three-dimensional monopole antennas when they are designed, but the key point of the present invention is to design a low-profile miniaturized planar monopole antenna, and to miniaturize the planar monopole antenna by using a zero-order resonance method, thereby reducing the size of the monopole patch, thereby ensuring that the monopole patch can be coplanarly placed inside the orthogonal dual-polarized microstrip antenna, greatly reducing the size and profile height of the entire antenna;

[0028] Another key point of the present invention is that the orthogonal dual-polarized microstrip antenna and the monopole antenna are placed in the same plane and do not touch each other. A large gap is left between the orthogonal dual-polarized microstrip antenna and the monopole patch, ensuring that each polarization of the three-polarized antenna has good isolation, reducing the mutual coupling effect between each polarization, and improving the efficiency of the antenna. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a structural diagram of a low-profile, wide-beam, tri-polarized antenna of the present invention.

[0030] Figure 2 The figure is a top view of a low-profile wide-beam tri-polarized antenna according to the present invention.

[0031] Figure 3 Schematic diagram of the antenna beam broadening principle loaded with a metal wall.

[0032] Figure 4 Schematic diagram of reflection coefficient of each port.

[0033] Figure 5 This is a schematic diagram of the isolation between ports.

[0034] Figure 6 are the normalized radiation patterns for different polarizations. DETAILED DESCRIPTION

[0035] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0036] like Figure 1 As shown, a low-profile wide-beam tri-polarized antenna is disclosed. The antenna includes a metal probe 1, a metal probe 2, a metal probe 3, a square radiation patch 4, a circular radiation patch 5, a circular parasitic patch 6, a rectangular parasitic patch 7, several grounding through holes, a dielectric substrate 11 and a metal floor 12.

[0037] Each part will be described in detail below.

[0038] like Figure 1 As shown, the square radiation patch 4 is fed by metal probe 1 and metal probe 2, and the circular patch 5 is fed by metal probe 3, wherein metal probe 1 is defined as port 1, and is an x-polarized antenna when fed alone, metal probe 2 is defined as port 2, and is a y-polarized antenna when fed alone, and metal probe 3 is defined as port 3, and is a z-polarized monopole antenna when fed alone.

[0039] The four grounding vias 10 are equivalent to parallel inductors, which can adjust the impedance matching of the square radiation patch 4 and increase the port isolation between the ports; the square radiation patch 4 is surrounded by four rectangular parasitic patches 7, each of which is connected to the metal floor 12 through three grounding vias 9, and the rectangular parasitic patches 7 and the grounding vias 9 play the role of widening the microstrip antenna beam; the circular radiation patch 5 is a z-polarized monopole antenna, which is fed by a metal probe 3, and the annular parasitic patch 6 is connected to the metal floor 12 through two metal vias 8, and is coupled and fed by the circular radiation patch 5. The annular parasitic patch 6 and the metal floor 12 can be equivalent to parallel capacitors and the metal via 8 is equivalent to a parallel inductor. The two can be equivalent to a parallel LC resonant circuit, so that the monopole patch resonates at high frequencies, thereby realizing the miniaturized design of the monopole antenna.

[0040] All the patches and metal floor 12 are placed on the same dielectric substrate 11, without the need for a multi-layer dielectric board. In addition, a three-dimensional monopole antenna is not used, but a planar monopole antenna with a lower height is used, which greatly reduces the cross-section of the three-polarized antenna.

[0041] Figure 2 This is a top view of the low-profile wide-beam tri-polarized antenna. The structure and main parameters of the antenna are as follows:

[0042] The antenna uses a square Rogers RO4350 dielectric board with a dielectric constant of 3.66, a thickness of 3.048 mm, and a side length of L1 = 16 mm;

[0043] The square radiation patch 4 , the circular radiation patch 5 , the annular parasitic patch 6 and the rectangular parasitic patch 7 are all printed on the upper surface of the dielectric substrate 11 , and the metal floor 12 is printed on the lower surface of the dielectric substrate 11 .

[0044] Metal probe one 1 and metal probe two 2 feed the square radiation patch 4; metal probe three 3 feeds the circular radiation patch 5; metal hole two 9 connects the rectangular parasitic patch 7 and the metal floor 12, and metal hole one 8 connects the circular parasitic patch 6 and the metal floor 12.

[0045] The square radiation patch 4 is located at the center of the upper layer of the dielectric substrate 11, with a side length of L2 = 8mm, and a circular hole with a radius of r1 = 2mm is dug out in the middle to place the circular radiation patch 5 and the annular parasitic patch 6. The center of the circular radiation patch 5 is located at the center of the upper layer of the dielectric substrate 11, with a radius of r2 = 0.6mm. The annular parasitic patch 6 and the circular radiation patch 5 are concentric circles, with an inner diameter of r3 = 0.8mm and an outer diameter of r4 = 1.05mm; the rectangular parasitic patch 7 is located around the square radiation patch 4, with a distance of D1 = 0.8mm between it and the square radiation patch 4, a length of L3 = 4mm, and a width of w1 = 2.2mm. The metal floor 12 is located at the lower layer of the dielectric plate 11, with a side length of L1 = 16mm;

[0046] A certain distance is left between the rectangular parasitic patch 7 and the square radiation patch 4 in order to couple out an induced current on the rectangular parasitic patch 7 .

[0047] The radius of the metal probe 1, the metal probe 2 and the metal probe 3 are all r6=0.3mm, wherein the distance between the metal probe 1 and the center of the dielectric substrate 11 is D4=2.5mm, the metal probe 2 is obtained by rotating 90° counterclockwise from the center of 1, and the center of the metal probe 3 is located at the exact center of the dielectric substrate 11;

[0048] The radius of metal hole 18 is r5 = 0.1mm, and the angle between it and the vertical direction (x direction in the figure) is θ = 45°. One metal hole 18 is obtained by rotating another metal hole 18 by 180° along the unit center. The radius of metal hole 29 is r8 = 0.25mm, and it is tangent to the inner side of the rectangular parasitic patch 7 (the inner side of the rectangular parasitic patch 7 is defined as the side close to the square radiation patch 4). The distance between two adjacent metal holes 29 is D3 = 1.5mm. The radius of metal hole 3 10 is r7 = 0.3mm, and the distance from the outer edge of the square patch 4 is D2 = 0.5mm.

[0049] Working principle of the present invention:

[0050] The present invention is a low-profile wide-beam tri-polarized antenna that can realize three linear polarization functions of x-polarization, y-polarization and z-polarization. The antenna is composed of a wide-beam orthogonal dual-polarized microstrip antenna and a planar monopole antenna, and the two antennas share a dielectric substrate 11 and a metal floor 12. The orthogonal dual-polarized microstrip antenna can realize x-polarization and y-polarization, and the monopole antenna can realize z-polarization;

[0051] Except for the dielectric substrate 11 and metal floor 12 shared by the two, the wide beam orthogonal dual polarization microstrip antenna part includes: metal probe 1, metal probe 2, square radiation patch 4, rectangular parasitic patch 7, metal hole 2 9 and metal hole 3 10. Among them, metal probe 1 and metal probe 2 2 can realize x and y line polarization when they are excited separately; there is a certain gap between the rectangular patch 7 and the square radiation patch 4. When the square radiation patch 4 is excited, an induced current can be coupled on the rectangular patch 7 through the gap. The induced current flows to the metal floor 12 through the metal hole 2 9, thereby generating a monopole-shaped directional pattern. The directional pattern generated by the induced current and the directional pattern generated by the square radiation patch are superimposed on each other, which plays a role in widening the antenna beam; the metal hole 3 10 plays a role in adjusting the impedance matching of the microstrip antenna.

[0052] The monopole antenna part includes a metal probe three 3, a circular radiation patch 5, a circular parasitic patch 6 and a metal hole 8.

[0053] When the metal probe 3 3 is excited alone, the antenna is a z-polarized antenna. The annular parasitic patch 6 can be equivalent to a parallel capacitor, and the metal hole 1 8 is equivalent to a parallel inductor; since there is a gap between the circular radiation patch 5 and the annular parasitic patch 6, when the metal probe 3 3 is excited, the circular radiation patch 5 will couple an induced current on the annular parasitic patch 6, and flow to the metal floor 12 through the metal hole 1 8, forming an LC resonant circuit, so that the monopole antenna resonates, thereby realizing the miniaturization design of the monopole antenna.

[0054] Figure 3 The schematic diagram of the beam broadening principle of the microstrip antenna is shown in FIG. A circle of metal electric walls is added near the square radiation patch 4, and a vertical current can be coupled on the electric wall. The vertical current radiates a horizontal directional pattern and superimposes the directional pattern of the main patch, which can achieve the effect of broadening the antenna beam. In order to reduce the antenna profile, the present invention folds the vertical electric wall, replaces the part beyond the dielectric substrate 11 with a rectangular parasitic patch 7, and replaces the part in the dielectric substrate 11 with a metal through hole 9, thereby greatly reducing the antenna profile and realizing the miniaturization design of the antenna. When the folded electric wall is placed completely symmetrically, a pair of opposite currents will be coupled on the two electric walls opposite to the H-plane of the antenna, so that the directional patterns generated by the two relatively placed vertical electric walls cancel each other, so that the H-plane beam of the antenna cannot be broadened, and only the E-plane beam can be broadened. Therefore, the present invention displaces the relative folded electric walls during design, that is, a pair of parasitic patches 7 and metal holes 9 with a spatial position difference of 180°; it is ensured that the directional patterns generated by the electric walls will not be completely offset, so that the H-plane beam of the antenna can also be broadened.

[0055] Figure 4The reflection coefficients of the various ports of the low-profile wide-beam tri-polarized antenna designed for the present invention are substantially the same for ports 1 and 2, with an operating range of 9.28-9.78 GHz, and a working range of port 3 of 9.57-9.64 GHz.

[0056] Figure 5 The isolation between the ports of the low-profile wide-beam tri-polarized antenna designed for the present invention shows that within the working range, the isolation between the ports is greater than 14 dB, and the isolation performance between the ports is good.

[0057] Figure 6 The normalized radiation pattern of a low-profile wide-beam tri-polarized antenna designed for the present invention at 9.6 GHz, Figure 6 (a) is the radiation pattern when port 1 is excited. At this time, the antenna is x-polarized, the E-plane beamwidth of the antenna is 142.7°, and the H-plane beamwidth is 136.2°; Figure 6 (b) is the radiation pattern when port 2 is excited. At this time, the antenna is y-polarized, the E-plane beamwidth of the antenna is 160.7°, and the H-plane beamwidth is 145.7°; Figure 6 (c) is the directional pattern when port 3 is excited. At this time, the directional pattern of the antenna is a monopole antenna, the E plane is an "∞" type, and the H plane is an omnidirectional antenna. Regardless of x-polarization or y-polarization, the beam width of the E plane and H plane of the antenna designed by the present invention exceeds 136°, and the beam broadening effect is very obvious. In addition, the z-polarization is a monopole antenna with good omnidirectional performance.

[0058] The present invention adopts a low-profile wide-beam orthogonal dual-polarization microstrip antenna, the antenna has a wider beam and a wider application scenario.

[0059] The present invention adopts a planar monopole antenna with a lower height, and the tri-polarized antenna has a lower profile, a smaller size, a higher strength and a lower cost.

[0060] In the present invention, the orthogonal dual-polarization microstrip antenna and the monopole patch are designed separately and do not contact each other. The isolation between polarizations is high and the mutual influence is small, which greatly improves the working efficiency of the antenna.

Claims

1. A low-profile wide-beam tri-polarized antenna, characterized in that: It comprises a dielectric substrate (11), wherein a square radiation patch (4), a circular radiation patch (5), a circular parasitic patch (6) and a rectangular parasitic patch (7) are printed on the upper surface of the dielectric substrate (11); and a metal floor (12) is arranged on the lower surface; Metal probe one (1) and metal probe two (2) are used to feed the square radiation patch (4); metal probe three (3) is used to feed the circular radiation patch (5); metal hole two (9) is used to connect the rectangular parasitic patch (7) and the metal floor (12); and metal hole one (8) is used to connect the circular parasitic patch (6) and the metal floor (12).

2. A low-profile wide-beam tri-polarized antenna according to claim 1, characterized in that: The square radiation patch (4) is located at the center of the upper layer of the dielectric substrate (11), and a circular hole is dug out in the middle for placing the circular radiation patch (5) and the annular parasitic patch (6).

3. A low-profile wide-beam tri-polarized antenna according to claim 1, characterized in that: The center of the circular radiation patch (5) is located at the center of the upper layer of the dielectric substrate (11), is arranged concentrically with the annular parasitic patch (6), and has a gap with the inner ring wall of the annular parasitic patch (6).

4. A low-profile wide-beam tri-polarized antenna according to claim 1, characterized in that: There are four rectangular parasitic patches (7), which are located around the square radiation patch (4) with a certain distance, and are symmetrically arranged along the center of the square radiation patch (4).

5. The low-profile wide-beam tri-polarized antenna according to claim 1, characterized in that: The metal probe 1 (1) is arranged at a certain distance from the center of the square radiation patch (4) along the x direction, the metal probe 2 (2) is arranged at a certain distance from the center of the square radiation patch (4) along the y direction, the metal probe 1 (1) and the metal probe 2 (2) are at an equal distance from the center of the square radiation patch (4), the center of the metal probe 3 (3) is located at the center of the dielectric substrate (11), and the x direction and the y direction are respectively the length and width directions of the square radiation patch (4).

6. A low-profile wide-beam tri-polarized antenna according to claim 5, characterized in that: Metal probe one (1), metal probe two (2) and metal probe three (3) correspond to three different polarizations when excited; When metal probe one (1) is excited alone, the antenna is an x-polarized antenna, when metal probe two (2) is excited alone, the antenna is a y-polarized antenna, and when metal probe three (3) is excited alone, the antenna is a z-polarized antenna.

7. A low-profile wide-beam tri-polarized antenna according to claim 1, characterized in that: There are two metal holes one (8) in total, which form an angle of θ=45° with the x direction. The two metal holes one (8) are symmetrically arranged with the metal probe three (3) as the center.

8. The low-profile wide-beam tri-polarized antenna according to claim 1, characterized in that: The second metal hole (9) is tangent to the inner side of the rectangular parasitic patch (7), the inner side of the rectangular parasitic patch (7) is defined as a side close to the square radiation patch (4), there are 12 second metal holes (9) in total, which are divided into 4 groups, with 3 holes in each group; Each group of metal holes (9) connects a rectangular parasitic patch (7) and a metal floor (12), and the remaining three groups are obtained by rotating one group along the center of the dielectric substrate (11) by 90 degrees, 180 degrees, and 270 degrees in sequence.

9. A low-profile wide-beam tri-polarized antenna according to claim 8, characterized in that: In a group of metal holes 2 (9), the tangent point between the middle metal hole 2 (9) and the rectangular parasitic patch (7) is located at the midpoint of the inner long side of the rectangular parasitic patch (7), and the other two metal holes are arranged at equal distances along both sides of the middle metal hole 2 (9); the metal hole 2 (9) and the rectangular parasitic patch (7) together play the role of widening the beam width of the microstrip antenna.

10. The low-profile wide-beam tri-polarized antenna according to claim 1, characterized in that: Metal holes three (10) are arranged at the four corners of the square radiation patch (4), and a total of four metal holes three (10) are arranged. The metal holes three (10) are located at a certain distance from the four corners of the square radiation patch (4), and play a role in adjusting the impedance matching of the square radiation patch (4).

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