A shared-radiator dual-port wideband self-decoupled MIMO antenna

Abstract

The present application relates to the technical fields of wireless communication antennas, and more particularly to a shared-radiator dual-port wideband self-decoupling MIMO antenna. The shared-radiator dual-port wideband self-decoupling MIMO antenna comprises a dielectric substrate (8), a metal ground arranged on one surface of the dielectric substrate (8), a shared-radiator (1) arranged on the other surface of the dielectric substrate (8), L-shaped slots (4) etched on the shared-radiator (1), square ring-shaped slots arranged on the periphery of the shared-radiator (1), a plurality of metalized short-circuit through holes (5), and a first feeding port (6) and a second feeding port (7). The shared-radiator (1) adopts a cross-shaped radiation patch structure, the first feeding port (6) and the second feeding port (7) are arranged on two mutually orthogonal radiation arms of the cross-shaped radiation patch (2) respectively, and the plurality of metalized short-circuit through holes (5) penetrate through the dielectric substrate (8) and connect the shared-radiator (1) and the metal ground.

Description

Technical Field

[0001] This invention relates to the field of wireless communication antenna technology, and more specifically to a shared radiator dual-port broadband self-decoupling MIMO antenna. Background Technology

[0002] With the rapid development of fifth-generation mobile communication technology, 5G communication systems have placed comprehensive performance requirements on antennas, including wide bandwidth, high isolation, miniaturization, and high integration. Multiple-input multiple-output (MIMO) technology, as an important means to improve system capacity and enhance spectrum utilization, has been widely used in wireless communication systems. Dual-port MIMO antennas, due to their simple structure, ease of integration, and ability to provide polarization diversity, have broad application prospects in 5G communication equipment. However, because the two radiating elements of a dual-port antenna are usually arranged in a limited space, strong electromagnetic coupling can easily occur between the ports, leading to reduced port isolation and increased envelope correlation coefficient, thus affecting the antenna's radiation performance and system communication capacity. Therefore, how to design a dual-port MIMO antenna that balances wide bandwidth coverage and high isolation within a compact structure has become an important research direction in the current antenna field.

[0003] Existing MIMO antenna decoupling methods mainly fall into two categories: external decoupling structures and self-decoupling structures. External decoupling structures typically employ defective ground structures, decoupling networks, neutralization lines, and parasitic elements to reduce inter-port coupling. While these methods can improve port isolation to some extent, they often require additional decoupling structures, occupying more space and potentially introducing additional losses, leading to bandwidth limitations and hindering antenna miniaturization and high-integration designs. Self-decoupling structures, on the other hand, optimize the antenna's own radiation structure and feeding method, utilizing the antenna's inherent radiation characteristics to suppress inter-port coupling. They require no additional decoupling devices and offer advantages such as compact structure and simple design. Among these, dual-port antennas based on shared radiators, by sharing the same radiation structure and combining orthogonal feeding methods to excite dominant surface currents in different directions, can achieve natural decoupling between ports, showing promising application prospects. However, existing dual-port antennas based on shared radiators still suffer from problems such as narrow operating bandwidth, difficulty in balancing broadband performance and isolation performance, and the need for further improvement in impedance matching performance, making it difficult to meet the application requirements of broadband, high-isolation dual-port MIMO antennas.

[0004] Currently, there is a low-profile eight-port MIMO antenna solution integrated into the back cover of a 5G mobile phone. This solution employs a two-layer dielectric substrate structure, with independent antenna pairs positioned at the four corners of the upper substrate. Each antenna pair includes a low-frequency annular radiating slot and a high-frequency ground radiating stub, coupled and fed through fan-shaped feed lines at the ends. Vertically arranged feed lines enhance the isolation within the unit. This solution achieves eight-port MIMO functionality through a distributed spatial arrangement of multiple units. However, its split radiating slot structure relies on the spatial distance between units to improve array isolation, resulting in a high number of overall structural layers and complex assembly. Furthermore, the separate combination of annular slots and ground stubs in a single radiating unit limits bandwidth expansion capabilities. It cannot simultaneously achieve broadband impedance matching and polarization orthogonal self-decoupling with a single shared radiator, making it difficult to meet the high integration requirements of compact single-unit dual-port MIMO antennas.

[0005] Therefore, there is a need to develop and design a broadband MIMO antenna based on a shared radiator and a polarization orthogonal self-decoupling mechanism, which can simultaneously achieve wide impedance bandwidth, high port isolation and low correlation in a limited space, and be suitable for compact multi-antenna integrated layouts in terminals such as smartphones. This is also a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the present invention provides a shared radiator dual-port broadband self-decoupling MIMO antenna, which aims to solve the problems of existing split-type multi-element MIMO antennas having a large number of structural layers, high assembly complexity, and the difficulty of a single shared radiator simultaneously achieving broadband performance and self-decoupling performance.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A shared radiator dual-port broadband self-decoupling MIMO antenna includes a dielectric substrate, a metal ground plane disposed on one surface of the dielectric substrate, a shared radiator disposed on the other surface of the dielectric substrate, an L-shaped slot etched on the shared radiator, a square annular slot disposed around the shared radiator, multiple metallized short-circuit vias, and a first feed port and a second feed port. The shared radiator adopts a cross-shaped radiating patch structure, with the first feed port and the second feed port respectively disposed on two mutually orthogonal radiating arms of the cross-shaped radiating patch. The multiple metallized short-circuit vias penetrate the dielectric substrate and connect the shared radiator to the metal ground plane.

[0008] Furthermore, the cross-shaped radiating patch includes a central connecting region and four radiating arms extending from the connecting region in four directions.

[0009] Furthermore, each of the four radiating arms of the cross-shaped radiating patch is symmetrically provided with folded square branches.

[0010] Furthermore, the L-shaped slit is located in the connection area between two adjacent radiating arms of the cross-shaped radiating patch.

[0011] Furthermore, the surface of the dielectric substrate where the shared radiator is disposed is also etched with a square annular slit, which is located around the shared radiator.

[0012] Furthermore, 12 metallized short-circuit vias penetrate the dielectric substrate and connect the shared radiator to the metal ground, and are symmetrically arranged around the four radiating arms of the cross-shaped radiating patch and the L-shaped slot.

[0013] Furthermore, the first feed port and the second feed port are respectively disposed on the longitudinal and transverse radiating arms of the cross-shaped radiating patch, and the feed directions of the two feed ports are orthogonal to each other.

[0014] Furthermore, the metal ground is printed on the lower surface of the dielectric substrate, and the shared radiator is disposed on the upper surface of the dielectric substrate.

[0015] Furthermore, the dielectric substrate is made of Flame Retardant Grade 4 material, which has a relative permittivity of 4.4, a loss tangent of 0.02, and an overall antenna size of 27mm × 27mm × 1.6mm.

[0016] Furthermore, the dual-port MIMO antenna system has a port isolation greater than 15dB, an envelope correlation coefficient less than 0.06, and an antenna efficiency of 60% to 71% in the 3.5GHz to 4.3GHz frequency band.

[0017] Compared to existing technologies, this invention achieves decoupling by exciting different ports to form orthogonal currents, eliminating the need for external components and significantly improving decoupling effectiveness and space saving. Based on this design, 12 metallized short-circuit vias are symmetrically placed on the substrate to optimize local current return paths. Simultaneously, two arc-shaped defect slots are etched on the right and lower arms of the cross-shaped radiating patch, connecting to their respective feed lines. This optimization enables dual-band coverage and significantly improves isolation levels, with two distinct resonance peaks observed in the S-parameter curve. To further extend the bandwidth, an L-shaped radiating slot is introduced within the central cross-shaped radiating patch. By adjusting the length and position of the L-shaped slot, the two resonant modes are brought closer and superimposed, ultimately extending the antenna's impedance bandwidth to its final effect. The stable isolation level across the entire bandwidth exceeds 15 dB, and this design comprehensively covers the main portion of the 5G NRn78 band (3.5-3.8 GHz). Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the overall structure of the shared radiator dual-port broadband self-decoupling MIMO antenna described in this invention. Figure 2 This is a schematic diagram illustrating the structural evolution of the antenna of the present invention; Figure 3 This is a schematic diagram of the simulation results corresponding to the structural evolution of the antenna of the present invention; Figure 4 This is a schematic diagram of the surface current distribution of the antenna of the present invention under excitation at different ports; Figure 5 This is the normalized radiation pattern of the antenna of the present invention in the xoy plane and yoz plane; Figure 6 This is a comparison chart of the simulation and actual measurement of the reflection coefficient and transmission coefficient of the antenna of this invention; Figure 7 The figure shows the simulation results of the envelope correlation coefficient and antenna efficiency of the antenna of this invention.

[0020] Among them, 1 is a shared radiator; 2 is a cross-shaped radiating patch; 3 is a folded square branch; 4 is an L-shaped slot; 5 is a metallized short-circuit via; 6 is the first feed port; 7 is the second feed port; and 8 is a dielectric substrate. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] This invention provides a shared radiator dual-port broadband self-decoupling antenna structure. By introducing an orthogonal feeding mechanism, an L-shaped slot, and a metallized short-circuit via into the shared radiating structure, broadband operation and high isolation characteristics are achieved, and excellent MIMO performance can be obtained without an additional decoupling network.

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, a detailed description is provided below in conjunction with the accompanying drawings.

[0024] refer to Figure 1This embodiment discloses a shared radiator dual-port broadband self-decoupling antenna structure, including a dielectric substrate 8, a metal ground plane printed on the lower surface of the dielectric substrate 8, a shared radiator 1 disposed on the upper surface of the dielectric substrate 8, and two feed ports. The shared radiator 1 includes a cross-shaped radiating patch 2, a folded square stub 3, an L-shaped slot 4, and a metallized short-circuit via 5. The dielectric substrate 8 is made of Flame Retardant Grade 4 material with a relative permittivity of 4.4, a loss tangent of 0.02, and a thickness of 1.6 mm. The overall antenna dimensions are 27 mm × 27 mm × 1.6 mm.

[0025] The cross-shaped radiating patch 2 serves as the main radiating structure, with folded square stubs 3 symmetrically loaded at its four arm ends. The folded square stubs 3 can extend the surface current path and increase the equivalent electrical length, thereby reducing the resonant frequency and enabling antenna miniaturization design.

[0026] L-shaped slots 4 are etched into the connection area of ​​adjacent radiating arms inside the cross-shaped radiating patch 2. By adjusting the length and position of the L-shaped slots 4, the surface current distribution can be changed, introducing new resonant modes and bringing multiple resonant modes closer together and coupling them, thereby widening the antenna impedance bandwidth.

[0027] Metallized short-circuit vias 5 penetrate the dielectric substrate 8 and connect the metal ground plane to the cross-shaped radiating patch 2. In this embodiment, a total of 12 metallized short-circuit vias 5 are provided, symmetrically distributed around the four radiating arms of the cross-shaped radiating patch 2 and the L-shaped slot 4. The metallized short-circuit vias 5 can optimize the current return path, enhance the resonant coupling effect, and improve the antenna impedance matching performance.

[0028] The surface of the dielectric substrate 8 where the shared radiator 1 is disposed is also etched with a square annular gap, which is located around the shared radiator 1 to further optimize the radiation current distribution and improve impedance matching performance.

[0029] refer to Figure 2 The following describes the structural evolution of the antenna of this invention and the corresponding simulation results. Antenna 1 consists only of a cross-shaped radiating patch 2 and a folded square branch 3; Antenna 2 adds a metallized short-circuit via 5 to antenna 1; The final structure of this invention further introduces an L-shaped slot 4 on the basis of antenna 2, and the final antenna design is obtained by adjusting the parameters of the L-shaped slot 4.

[0030] refer to Figure 3The performance of the antenna in this invention has been continuously improved during its evolution. Antenna 1 only excites a single resonant mode and has a narrow operating frequency band with weak isolation performance. The improved antenna 2 forms two independent resonant modes, achieving dual-frequency operation and increasing bandwidth. Further optimization resulted in antenna 3, which gradually brings the two resonant modes closer together and causes them to superimpose, improving both bandwidth and isolation performance. This verifies the combined effect of the L-shaped slot, cross-shaped radiating patch, and metallized short-circuit via.

[0031] refer to Figure 4 This is a schematic diagram illustrating the theoretical current distribution of the antenna under different port excitation conditions of the present invention. The first feed port 6 is connected to the bottom end of the longitudinal radiating arm of the cross-shaped radiating patch 2; the second feed port 7 is connected to the right end of the transverse radiating arm of the cross-shaped radiating patch 2. When the first feed port 6 is excited and the second feed port 7 is connected to a matching load, the dominant surface current on the shared radiator is mainly distributed longitudinally; when the second feed port 7 is excited and the first feed port 6 is connected to a matching load, the dominant surface current on the shared radiator is mainly distributed transversely. Since the dominant surface currents generated by the two port excitations are orthogonal to each other, the coupling term between them theoretically approaches zero, with only a very small stray current coupling, thus realizing the polarization orthogonal self-decoupling mechanism.

[0032] refer to Figure 5 The diagram shows the normalized radiation patterns of the dual-port shared radiator of this invention in the xoy and yoz planes. The results show that both ports can form stable radiation modes and maintain good orientation. Figure 1 The consistency verified the effectiveness of the shared radiation structure.

[0033] refer to Figure 6 The test results of the reflection coefficient and transmission coefficient of the dual-port antenna of the present invention are presented respectively. As can be seen from the figure, the antenna meets the impedance matching requirement of S11≤-10dB in the frequency band of 3.5GHz~4.3GHz, and the transmission coefficient between ports is always lower than -15dB, indicating that the antenna has good broadband characteristics and high isolation performance.

[0034] refer to Figure 7 The results of antenna system envelope correlation coefficient (ECC) and antenna efficiency tests are presented through calculations. The results show that the ECC between ports is less than 0.06 throughout the entire operating frequency band, indicating that the system has excellent spatial diversity capability; at the same time, the antenna efficiency remains at a high level, meeting the requirements of 5G terminal applications.

[0035] , The smaller the envelope correlation coefficient between antenna elements, the less the antenna elements are affected by each other when operating independently, and the channel capacity will not be affected. (See attached image) Figure 7As shown, the simulated ECC values ​​are all below 0.06 across all operating frequency bands, indicating good spatial diversity performance.

[0036] This invention provides a shared radiator dual-port broadband self-decoupling MIMO antenna. Existing decoupling techniques typically involve external devices, and the decoupling effect is not significant without them. In this invention, decoupling is achieved by exciting different ports to form orthogonal currents, eliminating the need for external devices and significantly improving both decoupling effectiveness and space saving. Based on this design, 12 metallized short-circuit vias are symmetrically placed on the substrate to optimize local current return paths. Simultaneously, two arc-shaped defect slots are etched on the right and lower arms of the cross-shaped radiating patch, connecting to their respective feed lines. After optimization, the antenna achieves dual-band coverage, and the isolation level is significantly improved, with two distinct resonance peaks observed in the S-parameter curve. To further extend the bandwidth, an L-shaped radiating slot is introduced within the central cross-shaped radiating patch. By adjusting the length and position of the L-shaped slot, the two resonant modes are brought closer and superimposed, ultimately extending the antenna's impedance bandwidth to the final effect. The stable isolation level across the entire bandwidth exceeds 15dB. This design comprehensively covers the main portion of the 5G NR n78 band (3.5-3.8 GHz).

[0037] Through step-by-step evolution, the L-shaped slot, cross-shaped radiating patch, and metallized short-circuit vias are combined to achieve the aforementioned technical effects. Specifically, this invention uses a cross-shaped radiating patch as the common radiating body for the dual ports, with folded square branches at the ends of the four radiating arms of the cross-shaped radiating patch. The cross-shaped radiating patch is used to construct a shared radiation path. However, at this point, the available antenna frequency range is limited, and the isolation effect is not excellent. Therefore, this structure is optimized and improved. Based on this design, 12 metallized short-circuit vias are symmetrically placed on the substrate to optimize the local current return path. After optimization, the antenna achieves dual-frequency coverage, and the isolation level is significantly improved, with two obvious resonance peaks observed in the S-parameter curve. To further extend the bandwidth, an L-shaped radiating slot is introduced within the central cross-shaped radiating patch. By adjusting the length and position of the L-shaped slot, the two resonant modes are brought closer and superimposed, ultimately extending the antenna's impedance bandwidth to the final effect. The stable isolation level of the entire bandwidth exceeds 15 dB. This design fully covers the main part of the 5G NR n78 band (3.5-3.8 GHz).

[0038] The three components mentioned above do not function independently, but rather work synergistically within the shared radiator: the L-shaped slot and the metallized short-circuit via jointly regulate the propagation path and phase distribution of the surface current, further enhancing the orthogonality of the dominant currents at the two feed ports. This allows the antenna to maintain broadband operation while effectively reducing inter-port coupling, achieving simultaneous improvements in broadband performance, self-decoupling performance, and impedance matching performance. Compared to existing shared radiator antennas, this invention, through the synergistic cooperation of the cross-shaped radiating patch, the L-shaped slot, and the metallized short-circuit via, achieves effective control of the dominant current mode and stray current mode within the shared radiator without adding any external decoupling structures. This results in a more stable polarization orthogonal radiation characteristic for the antenna, simultaneously achieving wide impedance bandwidth, high port isolation, and a low envelope correlation coefficient within the 3.5 GHz to 4.3 GHz operating frequency band, resulting in a comprehensive performance improvement that is difficult to achieve using any single structure alone.

[0039] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0040] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A shared radiator dual-port broadband self-decoupling MIMO antenna, characterized in that, The device includes a dielectric substrate (8), a metal ground on one surface of the dielectric substrate (8), a shared radiator (1) on the other surface of the dielectric substrate (8), an L-shaped slot (4) etched on the shared radiator (1), a square annular slot on the periphery of the shared radiator (1), multiple metallized short-circuit vias (5), and a first power supply port (6) and a second power supply port (7). The shared radiator (1) adopts a cross-shaped radiating patch structure. The first power supply port (6) and the second power supply port (7) are respectively disposed on two mutually orthogonal radiating arms of the cross-shaped radiating patch (2). Multiple metallized short-circuit vias (5) penetrate the dielectric substrate (8) and connect the shared radiator (1) to the metal ground.

2. The shared radiator dual-port broadband self-decoupling MIMO antenna according to claim 1, characterized in that, The cross-shaped radiating patch (2) includes a central connecting region and four radiating arms extending in four directions from the connecting region.

3. A shared radiator dual-port broadband self-decoupling MIMO antenna according to claim 1, characterized in that, The four ends of the four radiating arms of the cross-shaped radiating patch (2) are symmetrically provided with folded square branches (3).

4. A shared radiator dual-port broadband self-decoupling MIMO antenna according to claim 1, characterized in that, The L-shaped slit (4) is located in the connection area of ​​two adjacent radiating arms of the cross-shaped radiating patch (2).

5. A shared radiator dual-port broadband self-decoupling MIMO antenna according to claim 1, characterized in that, The surface of the dielectric substrate (8) on which the shared radiator (1) is provided is also etched with a square annular gap, which is located around the shared radiator (1).

6. A shared radiator dual-port broadband self-decoupling MIMO antenna according to claim 1, characterized in that, Twelve metallized short-circuit vias (5) penetrate the dielectric substrate (8) and connect the shared radiator (1) to the metal ground, and are symmetrically arranged around the four radiating arms of the cross-shaped radiating patch (2) and the L-shaped slot (4).

7. A shared radiator dual-port broadband self-decoupling MIMO antenna according to claim 1, characterized in that, The first feed port (6) and the second feed port (7) are respectively disposed on the longitudinal and transverse radiation arms of the cross-shaped radiation patch (2), and the feed directions of the two feed ports are orthogonal to each other.

8. A shared radiator dual-port broadband self-decoupling MIMO antenna according to claim 1, characterized in that, The metal ground is printed on the lower surface of the dielectric substrate (8), and the shared radiator (1) is disposed on the upper surface of the dielectric substrate (8).

9. A shared radiator dual-port broadband self-decoupling MIMO antenna according to claim 1, characterized in that, The dielectric substrate (8) is made of Flame Retardant Grade 4 material, with a relative permittivity of 4.4, a loss tangent of 0.02, and an overall antenna size of 27mm × 27mm × 1.6mm.

10. A shared radiator dual-port broadband self-decoupling MIMO antenna according to claim 1, characterized in that, The dual-port MIMO antenna system has a port isolation greater than 15dB, an envelope correlation coefficient less than 0.06, and an antenna efficiency of 60% to 71% in the 3.5GHz to 4.3GHz frequency band.

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