A low-profile wide-beam tri-polarized antenna

Abstract

The application discloses a low-profile wide-beam tri-polarized antenna, which comprises a dielectric substrate, a square radiation patch, a circular radiation patch, a circular ring-shaped parasitic patch and a rectangular parasitic patch printed on the upper surface of the dielectric substrate, a metal ground plate arranged on the lower surface of the dielectric substrate, a metal probe one and a metal probe two for feeding the square radiation patch, a metal probe three for feeding the circular radiation patch, a metal hole two for connecting the rectangular parasitic patch and the metal ground plate, and a metal hole one for connecting the circular ring-shaped parasitic patch and the metal ground plate. The metal through hole and the parasitic patch are used to replace the metal electric wall, so that the profile of the antenna is reduced. The application is applied to the tri-polarized antenna. Meanwhile, a planar monopole antenna with a lower height is adopted in the design of the tri-polarized antenna, so that 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 present 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, traditional single linear polarization antennas are facing limitations such as channel fading and limited channel capacity, limiting their further application. Design and Research of Triple-Polarized Conformal Microstrip Antennas [D]. Tsinghua University, 2009, proposes a conformable tri-polarized antenna unit. The antenna thickness is less than 0.08λ, and its vertically polarized antenna utilizes top loading to reduce its profile height. Its operating bandwidth is 7.6%. The antenna's horizontal dual polarization utilizes microstrip coupled feeding to improve the isolation between the three antenna ports, achieving an isolation greater than 16dB, enabling independent operation of the three polarization modes.

[0003] Research on a 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 was proposed. This tri-polarized antenna has a symmetrical structure, an operating bandwidth of 70 MHz, and a maximum isolation of -25.1 dB between antenna ports. In the omnidirectional E-plane, the difference between the main polarization and the cross-polarization is greater than 13 dB, and the difference between the main polarization and the cross-polarization of a single-chip antenna is greater than 16.5 dB. However, the tri-polarized antenna designed is composed of three mutually orthogonal slot antennas, which results in a large antenna size, high profile, and bulky volume, making it difficult to integrate with other circuits, limiting its application.

[0004] To reduce the size and profile of tri-polarized antennas, 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 pattern, while the square patch possesses two mutually orthogonal TM11 modes. The antenna has a thickness of 0.039λ, an operating bandwidth of 4%, and port isolation greater than 15dB. Although this antenna has a low profile, it still utilizes a double-layer dielectric plate and multi-order metal holes, making its structure complex. This complex structure significantly increases the antenna's processing cost. Furthermore, this tri-polarized antenna still uses a narrow-beam microstrip antenna, making it difficult to meet the requirements of wide-angle scanning.

[0005] In summary, the disadvantages of existing tri-polarized antenna technology are:

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

[0007] (2) The antenna beam is narrow, which makes it difficult to meet the requirements of wide-angle scanning. The antenna scanning efficiency is low and the application scenarios are limited.

[0008] (3) Although wide-beam antenna technology is now very mature, most wide-beam designs use asymmetric structures to widen the antenna beam. Tri-polarized antennas require symmetrical structures, which makes wide-beam antenna technology difficult to apply to tri-polarized antennas. In addition, most existing wide-beam antennas can only widen one side of the antenna (E-plane or H-plane), which also limits the application scenarios of wide-beam antennas. Summary of the Invention

[0009] To overcome the shortcomings of the aforementioned prior art, the present invention aims to provide a low-profile, wide-beam, tri-polarized antenna. Based on the principle of pattern superposition, the pattern generated by a centrally symmetrical metal barrier is superimposed with the pattern of the main radiating patch, effectively widening the beam of the microstrip antenna. Metal vias and parasitic patches are used in place of the metal barrier during design, thereby reducing the antenna's profile. Furthermore, when applied to a tri-polarized antenna, a planar monopole antenna with a lower height is employed, increasing the beam width of the tri-polarized antenna while reducing its profile, reducing its size, lowering its cost, improving its efficiency, and expanding its application scenarios.

[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 provided 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 for placing 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 concentrically arranged 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 therebetween 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 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, which are divided into 4 groups, with 3 holes in each group.

[0021] Each group of metal holes connects a rectangular parasitic patch and the 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 the role of widening the beam width of the microstrip antenna.

[0023] Metal holes three are provided at the four corners of the square radiation patch. There are four metal holes three in total. They are at a certain distance from the four corners of the square radiation patch, and play a role in adjusting 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, designing a tri-polarized antenna with wide-beam characteristics. Furthermore, the present invention implements a low-profile design for both the tri-polarized antenna and the wide-beam antenna, significantly reducing the antenna's implementation cost.

[0026] The present invention uses a staggered folded electric wall method to widen the beam of the microstrip antenna, that is, a pair of parasitic patches and metal holes are spatially positioned 180 degrees apart. The staggered structure designed by the present invention can widen the beam on both sides of the antenna, and this method can also reduce the cross-section of the antenna while widening the beam of the microstrip antenna.

[0027] Most tri-polarized antennas use three-dimensional monopole antennas when designing. However, the key point of the present invention is the design of a low-profile, miniaturized planar monopole antenna. The planar monopole antenna is miniaturized using zero-order resonance, reducing the size of the monopole patch. This ensures that the monopole patch can be placed coplanarly 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 between the polarizations 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 according to the present invention.

[0030] Figure 2 This 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 the 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 described in further detail below with reference to the accompanying drawings.

[0036] like Figure 1 As shown, a low-profile wide-beam tri-polarized antenna is disclosed. This antenna includes metal probe 1, metal probe 2, 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 when it is fed alone, it is an x-polarized antenna; metal probe 2 is defined as port 2, and when it is fed alone, it is a y-polarized antenna; metal probe 3 is defined as port 3, and when it is fed alone, the antenna is a z-polarized monopole antenna.

[0039] Four ground vias 10 are equivalent to parallel inductance, which can adjust the impedance matching of the square radiation patch 4 and increase the port isolation between each port; four rectangular parasitic patches 7 are around the square radiation patch 4, each rectangular parasitic patch 7 is connected with the metal ground plate 12 through three ground vias 9, the rectangular parasitic patch 7 and the ground via 9 play a role in widening the beam of the microstrip antenna; the circular radiation patch 5 is a z-polarized monopole antenna, which is fed through the metal probe three 3, the circular ring parasitic patch 6 is connected with the metal ground plate 12 through two metal vias 8 and is coupled and fed by the circular radiation patch 5, the circular ring parasitic patch 6 and the metal ground plate 12 can be equivalent to parallel capacitance and the metal via 8 is equivalent to parallel inductance, both of which can be equivalent to a parallel LC resonant circuit, so that the monopole patch resonates at high frequency and realizes the miniaturization design of the monopole antenna.

[0040] All the above patches and the metal ground plate 12 are placed on the same dielectric substrate 11, without the need for multiple dielectric plates, and without using a three-dimensional monopole antenna, a planar monopole antenna with a lower height is used, which greatly reduces the profile of the tri-polarized antenna.

[0041] Figure 2 It 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 plate with a dielectric constant of 3.66 and a thickness of 3.048 mm, and the side length L1 is 16 mm;

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

[0044] The metal probe one 1 and the metal probe two 2 feed the square radiation patch 4; the metal probe three 3 feeds the circular radiation patch 5; the metal hole two 9 connects the rectangular parasitic patch 7 and the metal ground plate 12, and the metal hole one 8 connects the circular ring parasitic patch 6 and the metal ground plate 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 L2=8mm, and a circular hole with a radius r1=2mm is cut in the middle to place the circular radiation patch 5 and the circular ring-shaped 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 r2=0.6mm, and the circular ring-shaped parasitic patch 6 and the circular radiation patch 5 are concentric circles, with an inner diameter r3=0.8mm and an outer diameter r4=1.05mm; the rectangular parasitic patch 7 is located around the square radiation patch 4, with a distance D1=0.8mm between the square radiation patch 4, a length L3=4mm, and a width w1=2.2mm. The metal floor 12 is located at the lower layer of the dielectric plate 11, with a side length L1=16mm;

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

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

[0048] The radius of the metal hole one 8 is r5=0.1mm, the angle between the metal hole one 8 and the vertical direction (the x direction in the figure) is θ=45°, and one metal hole one 8 is obtained by rotating another metal hole one 8 by 180° along the center of the unit. The radius of the metal hole two 9 is r8=0.25mm, and the metal hole two 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 the side close to the square radiation patch 4), and the distance between two adjacent metal holes two 9 is D3=1.5mm. The radius of the metal hole three 10 is r7=0.3mm, and the distance between the metal hole three 10 and the outer edge of the square patch 4 is D2=0.5mm.

[0049] The working principle of the application is as follows:

[0050] The application is a low-profile wide-beam tri-polarized antenna that can realize 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] Aside from the shared dielectric substrate 11 and metal floor 12, the wide-beam orthogonal dual-polarization microstrip antenna comprises: metal probe 1, metal probe 2, square radiating patch 4, rectangular parasitic patch 7, metal hole 2, and metal hole 3, 10. Metal probe 1 and metal probe 2 can achieve x- and y-linear polarization when excited individually. A gap exists between rectangular patch 7 and square radiating patch 4. When square radiating patch 4 is excited, an induced current is coupled through the gap on rectangular patch 7. This induced current flows through metal hole 2, 9, and metal floor 12, generating a monopole-like radiation pattern. The induced current pattern and the pattern generated by the square radiating patch overlap, widening the antenna beam. Metal hole 3, 10, adjusts the impedance matching of the microstrip antenna.

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

[0053] When metal probe 3 is excited alone, the antenna is a z-polarized antenna. The annular parasitic patch 6 is equivalent to a parallel capacitor, and the metal hole 1 8 is equivalent to a parallel inductor. Because there is a gap between the circular radiating patch 5 and the annular parasitic patch 6, when metal probe 3 is excited, the circular radiating patch 5 couples an induced current on the annular parasitic patch 6. This current flows through the metal hole 1 8 to the metal floor 12, forming an LC resonant circuit, causing the monopole antenna to resonate, thereby achieving a miniaturized monopole antenna design.

[0054] Figure 3 This is a schematic diagram of the beam-broadening principle of a microstrip antenna. Adding a metal barrier around the square radiating patch 4 couples a vertical current to the barrier. This vertical current radiates a horizontal pattern that superimposes with the main patch's pattern, effectively broadening the antenna's beam. To reduce the antenna's profile, the present invention folds the vertical barrier. The portion extending beyond the dielectric substrate 11 is replaced with a rectangular parasitic patch 7, and the portion within the dielectric substrate 11 is replaced with a metal via 9. This significantly reduces the antenna's profile and achieves a miniaturized design. When the folded barrier is perfectly symmetrically positioned, a pair of opposing currents are coupled to the two barriers facing the antenna's H-plane. This causes the patterns generated by the two opposing barriers to cancel each other, preventing H-plane beam broadening and allowing only E-plane beam broadening. Therefore, the present invention staggers the opposing folded barriers, placing the parasitic patch 7 and metal via 9 180° apart in spatial position. This ensures that the patterns generated by the barriers do not completely cancel each other out, thus broadening the antenna's H-plane beam.

[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 9.57-9.64 GHz for port 3.

[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 this invention at 9.6 GHz is as follows: 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) shows the directional pattern when port 3 is excited. At this point, the antenna's directional pattern is monopole-like, with the E-plane forming an "∞" shape and the H-plane omnidirectional. The beamwidth of the antenna designed in this invention exceeds 136° on both the E-plane and H-plane for both x- and y-polarization, demonstrating significant beam broadening. Furthermore, the antenna exhibits excellent omnidirectional performance when z-polarized, forming a monopole.

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

[0059] The present invention adopts a planar monopole antenna with a lower height, and the tri-polarized antenna has a lower profile, smaller size, higher strength and 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 the 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 provided on the lower surface; Metal probe 1 (1) and metal probe 2 (2) are used to feed the square radiation patch (4); The metal probe three (3) feeds the circular radiation patch (5); the metal hole two (9) connects the rectangular parasitic patch (7) and the metal floor (12); the metal hole one (8) connects the annular parasitic patch (6) and the metal floor (12); 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); 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); Metal holes three (10) are provided at the four corners of the square radiation patch (4), and there are four metal holes three (10) in total. The metal holes three (10) are 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); There are two metal holes (8) in total, which form an angle of θ=45° with the x-direction. The two metal holes (8) are symmetrically arranged with the metal probe (3) as the center. The spatial positions of the parasitic patch (7) and the second metal hole (9) differ by 180°; The second metal hole (9) is tangent to the inner side of the rectangular parasitic patch (7), and the inner side of the rectangular parasitic patch (7) is defined as the side close to the square radiation patch (4); 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°, 180°, and 270° in sequence.

2. The 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) at a certain distance and are symmetrically arranged along the center of the square radiation patch (4).

3. 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 the same 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).

4. The low-profile wide-beam tri-polarized antenna according to claim 3, 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.

5. The low-profile wide-beam tri-polarized antenna according to claim 1, characterized in that: There are 12 metal holes 2 (9) in total, divided into 4 groups, 3 holes in each group.

6. The low-profile wide-beam tri-polarized antenna according to claim 5, 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.

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