A circularly polarized self-decoupled stacked microstrip patch antenna with wide axial ratio bandwidth

Abstract

The application discloses a circularly-polarized self-decoupling stacked microstrip patch antenna with wide axial ratio bandwidth, which is a layered structure and comprises first and second parallelly arranged dielectric substrates, wherein an air layer is arranged between the first and second dielectric substrates, a rectangular parasitic metal patch is arranged on the upper surface of the first dielectric substrate, and each rectangular parasitic metal patch is connected with a continuously bent metal stub; a rectangular driving metal patch is arranged on the upper surface of the second dielectric substrate, and a metal ground is arranged on the lower surface of the second dielectric substrate. The application can realize wide axial ratio bandwidth and circularly-polarized self-decoupling of the stacked microstrip patch antenna without additional decoupling structure or circuit, and has the characteristics of simple structure, wide axial ratio bandwidth, self-decoupling, multi-antenna expansion, easy integration and the like, and is suitable for satellite communication, global positioning system and mobile communication and the like.

Description

Technical Field

[0001] This invention relates to a wide-axis-ratio, self-decoupled, multilayer microstrip patch antenna with circular polarization, belonging to the field of antenna technology in radio equipment. Background Technology

[0002] Multiple-input multiple-output (MIMO) technology can improve spectrum utilization, suppress multipath fading, and increase channel capacity without requiring additional spectrum resources, thus becoming a key technology in fifth-generation mobile communication systems. However, surface wave and space wave coupling between antenna elements in MIMO antenna arrays can reduce isolation and radiation efficiency, thereby affecting system performance. To address this, researchers have proposed various mutual coupling suppression methods, especially for microstrip patch antennas.

[0003] While traditional single-layer microstrip patch antennas offer low profile and ease of integration, their narrow bandwidth characteristics make them unsuitable for the broadband demands of 5G / Sub-6G. Stacked microstrip patch antennas (S-MPA) can achieve wider impedance bandwidth and beamwidth, with a relatively simple structure, thus becoming an important solution for broadband MIMO applications in recent years. Compared to linear polarization, circularly polarized S-MPA antennas can also reduce polarization mismatch loss and Faraday effect, and improve multipath resistance in complex environments, thus showing promise for applications in satellite communications, positioning, and mobile communications.

[0004] However, the decoupling design of circularly polarized stacked microstrip patch antennas is more complex: on the one hand, there are more potential mutual coupling paths in the stacked structure; on the other hand, impedance matching must be considered when suppressing mutual coupling of circularly polarized antennas. S 11 ), isolation ( S 21 The axial ratio (AR) and other performance characteristics increase the difficulty of broadband array design. Existing decoupling methods still have shortcomings: 1) Orthogonal polarization arrangement: When two antennas are working simultaneously, linear polarization components may be introduced, leading to a decrease in circular polarization performance; 2) Methods of adding additional decoupling structures (such as defective ground structures, "W"-shaped strips, etc.): Such methods can suppress surface waves and space waves through spatial band-stop filtering effects or current distribution control, but they are prone to increasing the back lobe of the radiation pattern, and the bandwidth is limited, the structure is complex, and it is difficult to extend to multi-element arrays. 3) Self-decoupling method by adjusting patch size: This method depends on the patch size ratio and feed point location, and is only applicable to single-layer patch antennas with limited bandwidth. 4) The method based on setting grooves and loading branches has limited improvement on isolation and available axial bandwidth, and fails to reflect the advantages of stacked structures in broadband.

[0005] In summary, existing decoupling methods for circularly polarized stacked microstrip patch antennas suffer from problems such as insufficient available bandwidth, limited improvement in isolation, or degradation of polarization characteristics, making it difficult to simultaneously meet the requirements of wideband matching, effective decoupling, and excellent axial ratio performance. Therefore, it is necessary to propose a wide axial ratio bandwidth, self-decoupling circularly polarized stacked microstrip patch antenna scheme. Summary of the Invention

[0006] Technical Problem: The purpose of this invention is to provide a wide-axis-ratio, self-decoupling, multilayer microstrip patch antenna with circular polarization, thereby solving the aforementioned technical problems existing in related technologies.

[0007] Technical solution: The wide axial ratio bandwidth circularly polarized self-decoupling stacked microstrip patch antenna of the present invention is achieved by the following technical measures: The antenna has a layered structure, including a first dielectric substrate and a second dielectric substrate arranged in parallel, with an air layer between them. On the upper surface of the first dielectric substrate, two adjacent rectangular parasitic metal patches are arranged side-by-side. Each rectangular parasitic metal patch is connected to one end of a continuously bent metal stub, the other end of which is located between the two adjacent rectangular parasitic metal patches. On the upper surface of the second dielectric substrate, two adjacent rectangular driving metal patches are arranged side-by-side. A metal ground is located on the lower surface of the second dielectric substrate. The rectangular driving metal patches are located directly below the rectangular parasitic metal patches and are fed by connected metal probes that pass through the second dielectric substrate and the metal ground to connect to the outside.

[0008] The center-to-center distance between two adjacent rectangular parasitic metal patches arranged side by side is 0.39λ. c , λ c It is the free-space wavelength at the center frequency of the antenna.

[0009] The center-to-center distance between two adjacent rectangular driving metal patches arranged side by side is 0.39λ. c , λ c It is the free-space wavelength at the center frequency of the antenna.

[0010] The shorter side of the rectangular parasitic metal patch is parallel to the arrangement direction of two adjacent rectangular parasitic metal patches arranged side by side, and the longer side is perpendicular to the arrangement direction. The length of the shorter side of the rectangular parasitic metal patch is 0.28λ. c - 0.3λ c Between these values, the length of the long side of the rectangular parasitic metal patch is 0.31λ. c - 0.34λ c Between, λ c It is the free-space wavelength at the center frequency of the antenna.

[0011] The short side of the rectangular driving metal patch is parallel to the arrangement direction of two adjacent rectangular driving metal patches arranged side by side, and the long side is perpendicular to the arrangement direction. The short side of the rectangular driving metal patch has the same length as the short side of the rectangular parasitic metal patch, and the long side of the rectangular driving metal patch is within 0.34λ. c - 0.36λ c Between, λ c It is the free-space wavelength at the center frequency of the antenna.

[0012] The continuously bent metal stub includes sequentially vertically connected functional branches, horizontal branches, and vertical branches. The widths of the functional branches, horizontal branches, and vertical branches are all consistent, all within 0.0018λ. c - 0.0021λ c Between these points, the length of the connecting functional branch is between 0.019λ. c - 0.021λ c Between these points, the length of the lateral branches is between 0.171λ. c - 0.174λ c Between these values, the length of the longitudinal branches is between 0.182λ. c - 0.185λ c Between, λ c It is the free-space wavelength at the center frequency of the antenna.

[0013] The position of the metal probe is offset from the center of each rectangular driving metal patch along the short side of the rectangular driving metal patch by an amount of 0.059λ. c - 0.061λ c Between these values, the offset along the long side of the rectangular driving metal patch is between 0.079λ. c - 0.082λ c Between, λ c It is the free-space wavelength at the center frequency of the antenna.

[0014] The thickness of the first dielectric substrate is 0.0091λ. c - 0.0094λ c The thickness of the second dielectric substrate is 0.024λ. c - 0.046λ c An air layer is added between the first dielectric substrate and the second dielectric substrate, λ c It is the free-space wavelength at the center frequency of the antenna.

[0015] The thickness of the air layer is 0.091λ. c - 0.095λ c , λ c It is the free-space wavelength at the center frequency of the antenna.

[0016] The materials of the first dielectric substrate and the second dielectric substrate are both polytetrafluoroethylene or epoxy resin.

[0017] Beneficial Effects: This invention adds an "η"-shaped stub, i.e., a continuously bent metal stub, to the parasitic patch of a traditional stacked microstrip patch antenna. In the latest Wi-Fi 6 wireless LAN standard (5.15-5.835 GHz), this structure introduces a new optimal circular polarization point in the low-frequency range (approximately 5.2 GHz) and enhances the optimal circular polarization point in the high-frequency range (approximately 5.7 GHz), thereby significantly widening the axial ratio bandwidth. The introduction of the stub also reduces the fundamental frequency TM. 10 Patterns and TM 01 The coupling frequency of the mode to the load causes the low-frequency mutual coupling zeros to fall into the operating frequency band, and further strengthens the inherent mutual coupling zeros at low and high frequencies, thereby improving decoupling performance and decoupling bandwidth. This realizes a circularly polarized stacked microstrip patch antenna with both wide axial ratio bandwidth and wide decoupling bandwidth. Attached Figure Description

[0018] Figure 1 This is a side cross-sectional view of a circularly polarized self-decoupling microstrip patch antenna array with a wide axial ratio bandwidth of 1×2 according to an embodiment of the present invention. Figure 2 This is a top front view of the first dielectric substrate of a circularly polarized self-decoupling microstrip patch antenna array with a 1×2 wide axial ratio bandwidth according to an embodiment of the present invention. Figure 3 This is a top front view of the second dielectric substrate of a circularly polarized self-decoupling microstrip patch antenna array with a 1×2 wide axial ratio bandwidth according to an embodiment of the present invention. Figure 4 This is a comparison of the S-parameter effects of a circularly polarized self-decoupling microstrip patch antenna array with a 1×2 wide axial ratio bandwidth according to an embodiment of the present invention, wherein... Figure 4 (a) is an example. Figure 4 (b) in the image is a conventional circularly polarized stacked microstrip patch antenna array; Figure 5 This is a comparison diagram of the axial ratio performance of a circularly polarized self-decoupling stacked microstrip patch antenna array with a 1×2 wide axial ratio bandwidth according to an embodiment of the present invention, wherein... Figure 5 (a) is an example. Figure 5 (b) in the image is a conventional circularly polarized stacked microstrip patch antenna array; Figure 6 This is the normalized radiation pattern of a circularly polarized self-decoupled stacked microstrip patch antenna array with a wide axial ratio bandwidth of 1×2 according to an embodiment of the present invention, wherein... Figure 6 (a) in the figure is the normalized radiation pattern of the XOZ plane at 5.15 GHz in the embodiment. Figure 6 (b) in the figure shows the normalized radiation pattern of the YOZ plane at 5.15 GHz in the embodiment. Figure 6 (c) in the figure shows the normalized radiation pattern of the XOZ plane at 5.85 GHz in the embodiment. Figure 6 (d) in the figure is the normalized radiation pattern of the YOZ plane at 5.85 GHz in the example; Figure 7 The root mean square (RMS) distribution of the electric field intensity of the rectangular driving metal patch in a circularly polarized self-decoupling microstrip patch antenna array with a 1×2 wide axial ratio bandwidth according to an embodiment of the present invention is shown below. Figure 7 (a) in the text is 5.15 GHz. Figure 7 (b) in the figure is 5.85 GHz; Figure 8 The electric field intensity distribution of the rectangular parasitic metal patch in a circularly polarized self-decoupling microstrip patch antenna array with a 1×2 wide axial ratio bandwidth according to an embodiment of the present invention is shown below. Figure 8 (a) shows the electric field intensity distribution in a 5.15 GHz embodiment under different phases when antenna a is fed and antenna b is connected to a 50Ω load; Figure 8 (b) shows the electric field intensity distribution in a 5.15 GHz embodiment under different phases when antenna b is fed and antenna a is connected to a 50Ω load; Figure 8 (c) in the example shows the electric field intensity distribution in different phases of the 5.85 GHz embodiment with antenna a fed by antenna a and antenna b connected to a 50Ω load; Figure 8 In the example, (d) represents the electric field intensity distribution under different phases of the 5.85 GHz embodiment with antenna b fed and antenna a connected to a 50Ω load; Figure 9 The envelope correlation coefficient of a circularly polarized self-decoupling stacked microstrip patch antenna array with a 1×2 wide axial ratio bandwidth according to an embodiment of the present invention; Figure 10 The image shows the S-parameter effect of a circularly polarized self-decoupling microstrip patch antenna array with a wide axial ratio bandwidth of 1×4 according to an embodiment of the present invention, wherein... Figure 10 In the example, (a) represents the reflection coefficient. Figure 10 In the example, (b) represents the level of mutual coupling between adjacent units. Figure 10 In the example, (c) represents the mutual coupling level between non-adjacent units; Figure 11 This is a diagram illustrating the axial ratio effect of a circularly polarized self-decoupling stacked microstrip patch antenna array with a 1×4 wide axial ratio bandwidth according to an embodiment of the present invention.

[0019] The figure includes: 1. Rectangular parasitic metal patch; 2. Continuously bent metal stubs; 3. First dielectric substrate; 4. Air layer; 5. Rectangular driving metal patch; 6. Second dielectric substrate; 7. Metal probe; 8. Metal ground; 201 connecting functional branch; 202 horizontal branch; and 203 vertical branch. Detailed Implementation

[0020] The present invention will now be described in detail through embodiments. It should be noted that these embodiments are only used to further illustrate the invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments based on the above description of the present invention.

[0021] The antenna has a layered structure, including a first dielectric substrate 3 and a second dielectric substrate 6 arranged in parallel, with an air layer 4 between the first dielectric substrate 3 and the second dielectric substrate 6; two adjacent rectangular parasitic metal patches 1 are arranged side by side on the upper surface of the first dielectric substrate 3, each rectangular parasitic metal patch 1 is connected to one end of a continuously bent metal stub 2, and the other end of the continuously bent metal stub 2 is located between the two adjacent rectangular parasitic metal patches 1; two adjacent rectangular driving metal patches 5 are arranged side by side on the upper surface of the second dielectric substrate 6, and a metal ground 8 is provided on the lower surface of the second dielectric substrate 6. The rectangular driving metal patches 5 are located directly below the rectangular parasitic metal patches 1 and are fed through a connected metal probe 7, which passes through the second dielectric substrate 6 and the metal ground 8 to connect to the outside. Example

[0022] The overall structure of the wide axial ratio bandwidth circularly polarized self-decoupling stacked microstrip patch antenna of the present invention is as follows: Figures 1-3 As shown, this wide-axis-ratio, bandwidth-optimized circularly polarized self-decoupling stacked microstrip patch antenna consists of a parasitic layer, an air layer, and a driving layer. Rectangular driving metal patches are arranged in a straight line, and the parasitic layer and driving layer are not electrically connected. It includes rectangular parasitic metal patches 1, continuously bent metal stubs 2, connecting functional stubs 201, lateral stubs 202, longitudinal stubs 203, a first dielectric substrate 3, an air layer 4, rectangular driving metal patches 5, a second dielectric substrate 6, metal probes 7, and a metal ground 8. Two adjacent rectangular parasitic metal patches 1 are disposed on the upper surface of the first dielectric substrate 3, with a center-to-center distance of 0.39λ. c Each rectangular parasitic patch 1 has its short side parallel to the patch arrangement direction and its long side perpendicular to that direction. The length of the short side of each parasitic patch is 0.29λ. c The length of the longer side is 0.33λ. c Each parasitic patch has a continuously bent short metal wire 2 connected to one end, and the other end of the short wire is located between two parasitic patches to introduce an electromagnetic coupling path in the parasitic layer.

[0023] Two adjacent rectangular driving metal patches 5 are disposed on the upper surface of the second dielectric substrate 6, with a center-to-center spacing of 0.39λ. c The short side of the rectangular driving patch 5 has the same length as the short side of the parasitic patch, which is 0.29λ. c Its longer side is 0.35λ. c The driving patch 5 and the parasitic patch 1 are arranged vertically opposite each other, separated by an air layer 4, thereby achieving electromagnetic coupling between the parasitic layer and the driving layer.

[0024] like Figure 2 As shown, the continuously bent metal stub 2 consists of three branches connected vertically in sequence: a connecting functional branch 201, a horizontal branch 202, and a vertical branch 203. All three have the same width of 0.002λ. c The length of the connecting functional branch 201 is 0.02λ. c The length of the lateral branch 202 is 0.172λ. c The length of longitudinal branch 203 is 0.184λ. c The bent stub introduces an additional coupling channel at the edge of the parasitic patch, which can effectively widen the circular polarization bandwidth and enhance self-decoupling capability.

[0025] Each driver patch 5 is fed via a metal probe 7. The probe 7 passes through the second dielectric substrate 6 and the metal ground 8 and then connects to an external feed line. The probe is offset by 0.06λ relative to the geometric center of the driver patch along its short side. c Offset by 0.08λ along the longer side. c This position can effectively excite the two orthogonal fundamental modes of the driving patch, thereby achieving right-hand circular polarization radiation.

[0026] The thickness of the first dielectric substrate 3 is 0.0093λ. c The thickness of the second dielectric substrate 6 is 0.036λ. c An air layer 4 with a thickness of 0.093λ is placed between the two. c The first dielectric substrate 3 and the second dielectric substrate 6 can be made of polytetrafluoroethylene (PTFE) or epoxy resin (FR-4). Preferably, a PTFE substrate with a relative permittivity εr=2.2 and a loss tangent tanδ=0.0009 is used to ensure low dielectric loss and stable electrical performance.

[0027] Simulation results show that the wide-axis-ratio bandwidth circularly polarized self-decoupling stacked microstrip patch antenna of this invention operates in right-hand circular polarization mode, achieving stable wide-angle radiation within the latest Wi-Fi 6 frequency band (5.15–5.835 GHz). Due to the stability of the right-hand circular polarization, the coupling received by the load is relatively balanced, thus placing the feed probe in a weak-field region over a wide frequency band, achieving a self-decoupling effect covering the entire operating frequency band. Within this band, the isolation between antenna elements increases from 13.6 dB before decoupling to over 20 dB overall; the 3 dB axial-ratio bandwidth of the antenna expands from 5.72–5.77 GHz (0.8%) before decoupling to 4.95–5.84 GHz (16.5%); and the envelope correlation coefficient remains at or below 0.001. This structure is easily expandable to multi-antenna systems. With its wideband circular polarization and excellent isolation performance, this antenna is suitable for multi-antenna communication systems and anti-multipath wireless applications, including wireless LANs, vehicle-to-everything (V2X) networks, drone communication links, and industrial IoT terminals.

Claims

1. A wide axial ratio bandwidth circularly polarized self-decoupled stacked microstrip patch antenna, characterized in that, The antenna has a layered structure, including a first dielectric substrate (3) and a second dielectric substrate (6) arranged in parallel. An air layer (4) is provided between the first dielectric substrate (3) and the second dielectric substrate (6). Two adjacent rectangular parasitic metal patches (1) are provided on the upper surface of the first dielectric substrate (3). Each rectangular parasitic metal patch (1) is connected to one end of an "η"-shaped stub, i.e., a continuously bent metal stub (2). The other end of the continuously bent metal stub (2) is located between the two adjacent rectangular parasitic metal patches (1). Two adjacent rectangular driving metal patches (5) are provided on the upper surface of the second dielectric substrate (6). A metal ground (8) is provided on the lower surface of the second dielectric substrate (6). The rectangular driving metal patches (5) are located directly below the rectangular parasitic metal patches (1) and are fed through a connected metal probe (7). The metal probe (7) passes through the second dielectric substrate (6) and the metal ground (8) to connect to the outside. The continuously bent metal stub (2) includes sequentially vertically connected functional branches (201), horizontal branches (202), and vertical branches (203). The widths of the functional branches (201), horizontal branches (202), and vertical branches (203) are consistent and all within 0.0018λ. c - 0.0021λ c Between these points, the length of the connecting functional branch (201) is between 0.019λ. c -0.021λ c Between these points, the length of the lateral branch (202) is 0.171λ. c - 0.174λ c Between these points, the length of the longitudinal branch (203) is 0.182λ. c - 0.185λ c Between, λ c It is the free-space wavelength at the center frequency of the antenna.

2. The wide aspect ratio bandwidth circularly polarized self-decoupled stacked microstrip patch antenna of claim 1, wherein, The center distance between the two adjacent rectangular parasitic metal patches (1) arranged side by side is 0.39λ c , λ c is the free space wavelength at the center frequency of the antenna.

3. The wide aspect ratio bandwidth circularly polarized self-decoupled stacked microstrip patch antenna of claim 1, wherein, The center distance between the two adjacent rectangular driving metal patches (5) arranged side by side is 0.39λ c , λ c is the free space wavelength at the center frequency of the antenna.

4. The wide aspect ratio bandwidth circularly polarized self-decoupled stacked microstrip patch antenna of claim 2, wherein, The short side of the rectangular parasitic metal patch (1) is parallel to the arrangement direction of two adjacent rectangular parasitic metal patches (1) arranged side by side, and the long side is perpendicular to the arrangement direction. The length of the short side of the rectangular parasitic metal patch (1) is 0.28λ. c - 0.3λ c Between these values, the length of the long side of the rectangular parasitic metal patch (1) is 0.31λ. c - 0.34λ c Between, λ c It is the free-space wavelength at the center frequency of the antenna.

5. The wide aspect ratio bandwidth circularly polarized self-decoupled stacked microstrip patch antenna of claim 3, wherein, The short side of the rectangular driving metal patch (5) is parallel to the arrangement direction of two adjacent rectangular driving metal patches (5) arranged side by side, and the long side is perpendicular to the arrangement direction. The short side of the rectangular driving metal patch (5) has the same length as the short side of the rectangular parasitic metal patch (1), and the long side of the rectangular driving metal patch (5) is 0.34λ. c - 0.36λ c Between, λ c It is the free-space wavelength at the center frequency of the antenna.

6. The wide aspect ratio bandwidth circularly polarized self-decoupled stacked microstrip patch antenna of claim 1, wherein, The position of the metal probe (7) relative to the center of each rectangular driving metal patch (5) is offset along the short side of the rectangular driving metal patch (5) by an amount of 0.059λ. c - 0.061λ c Between these points, the offset along the long side of the rectangular driving metal patch (5) is between 0.079λ. c - 0.082λ c Between, λ c It is the free-space wavelength at the center frequency of the antenna.

7. The wide aspect ratio bandwidth circularly polarized self-decoupled stacked microstrip patch antenna of claim 1, wherein, The thickness of the first dielectric substrate (3) is 0.0091λ. c - 0.0094λ c The thickness of the second dielectric substrate (6) is 0.024λ. c -0.046λ c An air layer (4) is added between the first dielectric substrate (3) and the second dielectric substrate (6), λ c It is the free-space wavelength at the center frequency of the antenna.

8. The wide axial ratio bandwidth circularly polarized self-decoupled stacked microstrip patch antenna of claim 7, wherein, The thickness of the air layer (4) is 0.091λ c - 0.095λ c , λ c is the free space wavelength at the center frequency of the antenna.

9. The wide axial ratio bandwidth circularly polarized self-decoupled stacked microstrip patch antenna of claim 7, wherein, The materials of the first dielectric substrate (3) and the second dielectric substrate (6) are both polytetrafluoroethylene or epoxy resin.

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