A circularly polarized decoupled patch antenna based on diagonal parasitic strip structure

Abstract

The present invention provides a circularly polarized decoupled patch antenna based on a diagonal parasitic strip structure, which belongs to the field of microwave millimeter wave communication technology. The technical problems of the existing circularly polarized antenna decoupling technology, such as complex structure, large size, excessive system layout space occupation, and inability to achieve directional pattern decoupling, are solved. The technical scheme is as follows: it includes an antenna substrate, main patches arranged in pairs on the antenna substrate, and a bottom metal layer, and also includes two groups of L-shaped parasitic strips, each group of L-shaped parasitic strips is arranged at the diagonal of one of the main patches, and a plurality of grounding through holes 1 are opened on one side of the L-shaped parasitic strip, a grounding through hole 2 is arranged at the free end of the other side of the L-shaped parasitic strip, and a coaxial feeding probe that passes through the antenna substrate. The beneficial effects of the present invention are as follows: the decoupling structure proposed by the antenna of the present invention is a decoupling structure composed of an L-shaped parasitic unit and a grounding through hole introduced at a group of diagonals of the patch antenna.

Description

Technical Field

[0001] This invention relates to the field of microwave and millimeter-wave communication technology, and in particular to a circularly polarized decoupling patch antenna based on a diagonal parasitic strip structure. Background Technology

[0002] With the continuous iteration and development of communication technology, wireless communication technology has evolved from 1G to 5G, and communication content has successively progressed from voice and text to today's image and video information. The ever-increasing demand for communication capacity necessitates the use of multi-antenna technology in communication systems to improve channel capacity. Simultaneously, multi-antenna communication systems must meet the development trends of miniaturization and integration. However, reducing the antenna spacing can lead to severe mutual coupling between adjacent antennas, affecting performance. Therefore, studying the causes of mutual coupling between adjacent antennas and designing antenna schemes to decouple them has become an important research topic.

[0003] To achieve decoupling between antennas, extensive research has been conducted both domestically and internationally, and numerous decoupling methods have been proposed:

[0004] I. Decoupling based on direct blocking of electromagnetic propagation.

[0005] When one or more pairs of antennas are working, surface waves and near fields between the antennas will be mutually coupled. If certain isolation measures are applied between the antennas to limit the surface waves and near fields generated by the antennas to a certain area and avoid affecting other antennas, the mutual coupling between the antennas can be significantly reduced.

[0006] Based on this principle, ① a metamaterial structure with spatial band-stop characteristics can be loaded between two antennas. Due to its band-stop transmission characteristics, by adjusting the structure and periodic arrangement of the metamaterial, the coupling field between the antennas can be prevented from propagating within a specific frequency, thereby reducing mutual coupling between the antennas. ② An electromagnetic resonant ring with negative relative permeability can be loaded between the antennas. When this resonant ring resonates at a specific frequency, it exhibits electromagnetic characteristics with negative relative permeability for electromagnetic waves in that frequency band. Therefore, electromagnetic waves cannot form an effective propagation mode within this frequency band, thus reducing mutual coupling. ③ An electromagnetic bandgap (EBG) structure, due to the discontinuous nature of the EBG's operating frequency, has a frequency interval in its operating mode response. Therefore, electromagnetic energy cannot propagate normally within a specific frequency band, thus reducing mutual coupling. ④ A defective ground structure (DGS), which exhibits good band-stop characteristics within a specific operating frequency band, reduces mutual coupling.

[0007] II. Cancellation based on constructing additional coupling paths

[0008] In a multi-antenna system, when an antenna is excited, it radiates electromagnetic waves. Some of these waves radiate into free space, while others radiate onto adjacent antennas, creating coupling – this is direct coupling between antennas. Based on the mutual coupling of antennas, besides the direct blocking method described in Method 1, if an additional coupling path is introduced between antenna elements to create indirect coupling, and if the indirect and direct couplings satisfy equal amplitude and a phase difference of π, they can cancel each other out, thus reducing antenna mutual coupling.

[0009] Based on this principle, ① a neutral line is constructed connecting the antenna radiating elements. Introducing an additional metallic coupling loop between antennas can effectively reduce coupling between ports. ② A decoupling network is constructed between the ports. A set of decoupling networks is built between the ports so that some of the energy coupled through the decoupling network cancels out the radiated energy coupled through the antenna elements at the ports, achieving decoupling. ③ An additional dielectric layer is added for antenna element coupling. A decoupling surface (frequency selective surface) is added to the top of the antenna elements so that the electromagnetic energy coupled through the decoupling surface cancels out the electromagnetic energy coupled between the antenna elements, thus achieving port decoupling between the antenna elements.

[0010] In existing designs, most linearly polarized antennas use the two methods mentioned above for decoupling. Compared to linearly polarized antennas, circularly polarized antennas have advantages such as omnidirectionality, ease of adjustment, and wide signal coverage. Furthermore, circularly polarized antennas can suppress multipath interference, reduce polarization mismatch, and overcome the Faraday effect, making them more suitable for radar, satellite communication systems, and GPS. However, decoupling circularly polarized antennas requires consideration not only of bandwidth and radiation pattern but also of circular polarization performance, as both must be balanced simultaneously, making decoupling more challenging. Some existing circularly polarized decoupling designs are only applicable to a pair of circularly polarized antennas with opposite polarizations. This leads to interference between the two orthogonal polarized waves when both antennas operate simultaneously, forming linearly polarized waves and affecting performance. Therefore, designing an antenna that balances both circular polarization performance and decoupling has significant academic and engineering applications.

[0011] Existing circularly polarized decoupling antennas still have the following technical drawbacks:

[0012] First, the added decoupling structures occupy a large space and are complex. Most existing circularly polarized decoupling antenna designs choose to add structures such as electromagnetic bandgap, defective ground, wide-side coupled split-loop resonator (BC-SSR), and "W"-shaped strips between the antennas. These structures occupy a lot of space and reduce the integration of the antenna.

[0013] Secondly, it is difficult to balance the radiation performance of circular polarization with decoupling. In order to achieve low mutual coupling, some circularly polarized decoupling antennas often have to sacrifice the radiation performance of circular polarization, resulting in radiation pattern distortion.

[0014] Third, it is only applicable to pairs of circularly polarized antennas with opposite polarizations. Some designs are only suitable for a pair of circularly polarized antennas with opposite polarizations. This not only causes the two orthogonal circularly polarized waves to superimpose and form linearly polarized waves when the antennas work together, affecting radiation performance, but also prevents such antennas from forming arrays of more antennas.

[0015] How to solve the above-mentioned technical problems is the challenge facing this invention. Summary of the Invention

[0016] The purpose of this invention is to provide a circularly polarized decoupling patch antenna based on a diagonal parasitic strip structure. This circularly polarized decoupling antenna achieves an axial ratio bandwidth of 4.88-4.97 GHz and low mutual coupling as low as -50 dB within the band, while maintaining a simple structure and not occupying excessive space. Firstly, complex structures such as electromagnetic band gaps and defective grounds cannot be used; the decoupling method must be simple and space-efficient. Secondly, the radiation performance of circular polarization must be guaranteed while ensuring decoupling. Thirdly, the decoupling of co-rotating circularly polarized antennas ensures circular polarization performance when the antennas are working together. The circularly polarized decoupling antenna proposed in this invention fully considers how to achieve low mutual coupling while ensuring circular polarization performance. Its structure is simple and space-efficient; with a center-to-center spacing of 0.4λ0, its axial ratio relative bandwidth is 1.8%. Compared to a group of circularly polarized antennas with the same center-to-center spacing of 0.4λ0 but without any decoupling methods, the in-band mutual coupling can decrease from -12 dB to below -25 dB, with a minimum of -50 dB.

[0017] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: a circularly polarized decoupling patch antenna based on a diagonal parasitic strip structure, comprising an antenna substrate, a pair of main patches arranged opposite to each other on the antenna substrate, and a bottom metal layer.

[0018] It also includes two sets of L-shaped parasitic strips, each set of L-shaped parasitic strips is arranged at the diagonal of one of the main patches, several grounding through holes one on one side of the L-shaped parasitic strip, a grounding through hole two at the free end of the other side of the L-shaped parasitic strip, and a coaxial feed probe penetrating the antenna substrate 1.

[0019] As a circularly polarized decoupling patch antenna based on a diagonal parasitic strip structure provided by the present invention, the main patch and the L-shaped parasitic strip are located at the top of the antenna substrate, and the bottom metal layer is located at the bottom of the antenna substrate.

[0020] As a circularly polarized decoupling patch antenna based on a diagonal parasitic strip structure provided by the present invention, in each main patch, one of the two L-shaped parasitic strips is provided with a grounding through hole II at one end, and the other L-shaped parasitic strip is provided with a section of a plurality of grounding through holes I at one end.

[0021] As a circularly polarized decoupling patch antenna based on a diagonal parasitic strip structure provided by the present invention, the L-shaped parasitic strip, grounding via one and grounding via two are the main decoupling structures of the antenna. These two structures are arranged diagonally on the antenna and are closely spaced from the main patch. These decoupling structures can ensure the decoupling effect and circular polarization performance while occupying a small area and having low complexity.

[0022] When the right antenna is excited alone, a coupling current is generated not only on the main patch of the left antenna, but also on the L-shaped parasitic strip. However, the amplitude and phase of the coupling current on the parasitic structure are significantly different from those on the main patch. After the two are superimposed, the left antenna degenerates into an antenna that is approximately linearly polarized. The weak field distribution at the coaxial feed probe is maintained, achieving the effect of decoupling.

[0023] As a circularly polarized decoupling patch antenna based on a diagonal parasitic strip structure provided by the present invention, the grounding through hole one, the grounding through hole two, and the coaxial feed probe each penetrate through the antenna substrate.

[0024] As a circularly polarized decoupling patch antenna based on a diagonal parasitic strip structure provided by the present invention, the width of one side of the L-shaped parasitic strip with grounding through hole two is greater than the width of the side with grounding through hole one.

[0025] As a circularly polarized decoupling patch antenna based on a diagonal parasitic strip structure provided by the present invention, the coaxial feed probe is located outside the center of the main patch and connects the main patch to the antenna substrate.

[0026] As a circularly polarized decoupling patch antenna based on a diagonal parasitic strip structure provided by the present invention, the antenna substrate adopts an Arlon AD450(tm) substrate.

[0027] As a circularly polarized decoupling patch antenna based on a diagonal parasitic strip structure provided by the present invention, the antenna substrate (1) has a size of 40mm*70mm*2.286mm.

[0028] As provided by this invention, a circularly polarized decoupling patch antenna based on a diagonal parasitic strip structure is provided, wherein the center spacing of the antenna is 0.3λ0-0.5λ0.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] 1. The present invention achieves the effect of decoupling by constructing L-shaped parasitic strips and grounding vias on a set of diagonals of a circularly polarized antenna.

[0031] 2. The decoupling structure proposed in this invention is a decoupling structure consisting of an L-shaped parasitic element and a grounding via introduced at a set of diagonal points of the patch antenna.

[0032] 3. The decoupling structure of the present invention is not only applicable to the 4.8-5.1GHz frequency band, but can also be extended to other frequency bands.

[0033] 4. Simple structure: Most existing circular polarization decoupling antenna designs choose to load structures such as electromagnetic band gaps, defective grounds, wide-side coupled split-loop resonators (BC-SSR), and "W"-shaped strips between antennas. These structures occupy a lot of space and reduce the integration of the antenna. This invention only needs to load L-shaped parasitic strips and grounding vias at the diagonal of the antenna to achieve good decoupling effect and circular polarization performance.

[0034] 5. Balancing decoupling effect and circular polarization performance: Some existing circular polarization decoupling antennas often sacrifice the radiation performance of circular polarization to achieve low mutual coupling. In this way, even if there is a good decoupling effect, the radiation pattern of the circular polarization antenna itself may be degraded. This invention can achieve an axial ratio bandwidth of 4.88-4.97GHz and a minimum mutual coupling of -50dB within the frequency band without significantly affecting the radiation performance of the antenna itself. Attached Figure Description

[0035] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0036] Figure 1 This is a front view of the decoupled antenna pair in this invention.

[0037] Figure 2 This is a schematic diagram of the decoupling antenna pair in this invention.

[0038] Figure 3 This is a detailed structural diagram of a single antenna in this invention.

[0039] Figure 4 This is a schematic diagram of an example antenna in an embodiment of the present invention.

[0040] Figure 5 This is a schematic diagram of the comparative antenna structure in an embodiment of the present invention.

[0041] Figure 6 This is a comparison chart of antenna reflection coefficient curves in embodiments of the present invention.

[0042] Figure 7This is a comparison chart of the reflection coefficient curves of the comparative antennas in the embodiments of the present invention.

[0043] Figure 8 This is a graph showing the comparison of antenna axial ratio performance in an embodiment of the present invention.

[0044] Figure 9 This is a comparison curve of the antenna axial ratio performance in an embodiment of the present invention.

[0045] Figure 10 This is the radiation pattern of the antenna when phi = 0° in an embodiment of the present invention.

[0046] Figure 11 This is the radiation pattern of the antenna when phi = 90° in an embodiment of the present invention.

[0047] Figure 12 This is a radiation pattern of the comparison antenna when phi = 0° in an embodiment of the present invention.

[0048] Figure 13 This is a radiation pattern of the comparison antenna when phi = 90° in an embodiment of the present invention. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. Of course, the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0050] Example 1

[0051] See Figures 1 to 3 The technical solution provided in this embodiment is as follows: In order to achieve the above-mentioned invention objective, the technical solution adopted in this embodiment is as follows: a circularly polarized decoupling patch antenna based on a diagonal parasitic strip structure, including an antenna substrate 1, a pair of main patches 2 arranged opposite to each other on the antenna substrate 1, and a bottom metal layer 3.

[0052] It also includes two sets of L-shaped parasitic strips 4, each set of L-shaped parasitic strips 4 being arranged at opposite corners of one of the main patches 2, several grounding through holes 5 on one side of the L-shaped parasitic strip 4, a second grounding through hole 6 at the free end of the other side of the L-shaped parasitic strip 4, and a coaxial feed probe 7 penetrating the antenna substrate 1.

[0053] Specifically, the main patch 2 and the L-shaped parasitic strip 4 are located on the top of the antenna substrate 1, and the bottom metal layer 3 is located on the bottom of the antenna substrate 1.

[0054] Specifically, in each main patch 2, one of the two L-shaped parasitic strips 4 is provided with a grounding through hole 6 at one end, and the other L-shaped parasitic strip 4 is provided with a section of grounding through holes 5 at the other end.

[0055] Specifically, the L-shaped parasitic strip 4, grounding through hole 1 5, and grounding through hole 2 6 are the main decoupling structures of the antenna. These two structures are arranged diagonally on a pair of antennas and are closely spaced from the main patch 2. These decoupling structures can ensure the decoupling effect and circular polarization performance while occupying a small area and having low complexity.

[0056] When the right antenna is excited alone, a coupling current is generated not only on the main patch 2 of the left antenna, but also on the L-shaped parasitic strip 4. However, the amplitude and phase of the coupling current on the parasitic structure are significantly different from those on the main patch 2. After the two are superimposed, the left antenna degenerates into an antenna that is approximately linearly polarized. The weak field distribution at the coaxial feed probe 7 is maintained, achieving the effect of decoupling.

[0057] Specifically, the grounding through hole 5, the grounding through hole 6, and the coaxial feed probe 7 each penetrate through the antenna substrate 1.

[0058] Specifically, the width of the side of the L-shaped parasitic strip 4 with grounding hole 2 6 is greater than the width of the side with grounding hole 1 5.

[0059] Specifically, the coaxial feed probe 7 is located outside the center of the main patch 2 and connects the main patch 2 to the antenna substrate 1.

[0060] Specifically, the antenna substrate 1 is an Arlon AD450(tm) substrate.

[0061] Specifically, the antenna substrate 1 has dimensions of 40mm*70mm*2.286mm.

[0062] Specifically, the center-to-center spacing of the antennas is 0.4λ0.

[0063] Example 2

[0064] Based on Example 1, to demonstrate antenna performance, a set of examples are provided for reference. The example antennas are as follows: Figure 4 As shown, the substrate uses an Arlon AD450(tm) substrate with a dielectric constant of 4.5 and a loss of 0.0035. The substrate dimensions are 40mm * 70mm * 2.286mm, and the center-to-center spacing of the antennas is 0.4λ0. A set of circularly polarized antennas, also operating at 4.9GHz with a center-to-center spacing of λ0, is used as a control antenna. Figure 5 As shown. The reflection coefficient of the case antenna is as follows. Figure 6 As shown, the reflection coefficient of the comparison antenna is as follows: Figure 7 As shown, compared to the comparison antenna, the antenna with the decoupling structure exhibits a significant reduction in in-band mutual coupling energy from -12dB to below -25dB, with a minimum of -50dB, demonstrating excellent decoupling performance. The axial ratio performance of the case antenna is shown below. Figure 8 As shown, the axial ratio performance of the antennas is compared as follows: Figure 9 As shown, the axial ratio performance is restored after loading the decoupling structure, and when both ports work together, the two sets of circularly polarized waves do not superimpose into a linearly polarized wave, thus functioning normally. The radiation performance of the case antenna is shown below. Figure 10 , Figure 11 As shown, the radiation performance of the comparative antennas is as follows: Figure 12 , Figure 13 As shown, the radiation pattern of the case antenna was well recovered compared to the comparison antenna.

[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A circularly polarized decoupled patch antenna based on a diagonal parasitic strip structure, characterized in that: It comprises an antenna substrate (1), main patches (2) and a bottom metal layer (3) arranged in pairs on the antenna substrate (1); It also includes two groups of L-shaped parasitic strips (4), each group of L-shaped parasitic strips (4) is arranged at the diagonal position of one of the main patches (2), a plurality of grounding through holes (5) are provided on one side of the L-shaped parasitic strips (4), a grounding through hole (6) is provided at the free end of the other side of the L-shaped parasitic strips (4), and a coaxial feeding probe (7) passes through the antenna substrate (1); The main patch (2) and the L-shaped parasitic strip (4) are located on the top of the antenna substrate (1), and the bottom metal layer (3) is located on the bottom of the antenna substrate (1); In the two L-shaped parasitic strips (4) of each main patch (2), one end of one of the L-shaped parasitic strips (4) having a second grounding through hole (6) is arranged adjacent to a section of the other L-shaped parasitic strip (4) having a plurality of first grounding through holes (5); The width of one side of the L-shaped parasitic strip (4) provided with the second grounding through hole (6) is greater than the width of one side provided with the first grounding through hole (5).

2. The circularly polarized decoupled patch antenna based on a diagonal parasitic strip structure according to claim 1, characterized in that: The L-shaped parasitic strip (4), the first grounding through hole (5) and the second grounding through hole (6) are decoupling structures of the antenna. The two structures are arranged at a set of diagonal positions of the antenna and are closely spaced from the main patch (2).

3. The circularly polarized decoupled patch antenna based on a diagonal parasitic strip structure according to claim 1, characterized in that: The first grounding through hole (5), the second grounding through hole (6) and the coaxial feeding probe (7) respectively penetrate the antenna substrate (1).

4. The circularly polarized decoupled patch antenna based on a diagonal parasitic strip structure according to claim 3, characterized in that: The coaxial feeding probe (7) is located outside the center of the main patch (2) and connects the main patch (2) to the antenna substrate (1).

5. The circularly polarized decoupled patch antenna based on a diagonal parasitic strip structure according to claim 1, characterized in that: The antenna substrate (1) is an Arlon AD450(tm) substrate.

6. The circularly polarized decoupled patch antenna based on a diagonal parasitic strip structure according to claim 1, characterized in that: The antenna substrate (1) has a size of 40 mm*70 mm*2.286 mm.

7. The circularly polarized decoupled patch antenna based on a diagonal parasitic strip structure according to claim 1, characterized in that: The center distance between the antennas is 0.3λ0-0.5λ0.

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