A dual-port antenna applied to a zero-clearance mobile terminal

Abstract

A kind of dual-port antenna applied to zero-clearance mobile terminal, including horizontal dielectric plate, both sides of the horizontal dielectric plate are respectively provided with vertical dielectric plate, the inner surface of the vertical dielectric plate is provided with radiator, the two ends of the radiator and located on the upper surface of horizontal dielectric plate are respectively provided with first port feed network and second port feed network, the back of the horizontal dielectric plate is etched with metal floor;The present application adopts multi-port antenna form, two radio frequency ports jointly excite same antenna radiator, and introduce coupling gap on radiator, reduce the size of antenna radiator, integrated antenna pair has lower standing wave ratio, LC series resonance circuit is introduced between the middle position of radiator and metal floor, so that the isolation between two radio frequency ports is kept higher, the antenna of the present application and metal floor have no clearance area, can be applied to zero-clearance mobile terminal equipment, with high isolation characteristic and compact structure characteristics.

Description

Technical Field

[0001] This invention belongs to the field of antenna technology, specifically relating to a dual-port antenna for use in zero-headroom mobile terminals. Background Technology

[0002] With the miniaturization and widening of mobile terminal devices, the clearance space left for antennas is getting smaller and smaller. Therefore, the demand for terminal antennas in the case of small clearance or zero clearance is becoming more and more urgent. The problems faced at this time are that the antenna bandwidth is narrowing and the radiation efficiency is decreasing. At the same time, in order to further improve the communication capacity of MIMO system, the number of antennas configured is increasing. This leads to increased antenna coupling and poor isolation. Currently, the isolation between antenna ports is generally required to be greater than 10dB.

[0003] MIMO technology typically involves setting up multiple antennas at the receiver and transmitter of a wireless communication system to achieve spatial diversity. However, this also creates coupling issues between the multiple antennas. 5G mobile terminal devices have very limited space for antennas, and placing multiple antennas in a limited space will inevitably lead to strong coupling effects, affecting the performance of the MIMO antenna system. How to maintain the performance of the MIMO antenna system within the limited space of a 5G mobile terminal is one of the research hotspots.

[0004] The literature [L. Sun, H. Feng, Y. Liand Z. Zhang, "Compact 5G MIMO Mobile Phone Antennas With Tightly Arranged Orthogonal-Mode Pairs," in IEEE Transactions on Antennas and Propagation, vol. 66, no. 11, pp. 6364-6369, Nov. 2018] proposes an antenna pair consisting of a curved monopole and an edge-fed dipole. The metal ground plane has a size of 150 mm × 73 mm, operates in the 3.4-3.6 GHz frequency band, achieves an isolation of 17 dB, has a size of 12 mm × 7 mm, a clearance of 1 mm, and a radiation efficiency greater than 49%.

[0005] The literature [Y. Ye, X. Zhao and J. Wang, "Compact High-Isolated MIMO Antenna Module With Chip Capacitive Decoupler for 5G Mobile Terminals," in IEEE Antennas and Wireless Propagation Letters, vol. 21, no. 5, pp. 928-932, May 2022] proposes a compact antenna pair based on capacitive decoupling, with dimensions of 16mm × 6mm, operating frequency band of 3.42-3.69GHz, antenna isolation better than 10dB, radiation efficiency greater than 53%, and a net area of ​​5mm. A ring structure is also set between the elements for decoupling.

[0006] In summary, existing mobile terminal MIMO antenna systems mainly suffer from the following problems:

[0007] 1. For mobile terminal devices, the antenna is generally one port that excites one antenna radiator.

[0008] 2. Current mobile terminal devices have complex internal structures, and integrated components occupy too much internal space, leaving very little clearance for the antenna. The smaller the clearance, the worse the antenna's radiation performance.

[0009] 3. To suppress mutual coupling between antennas on mobile terminal platforms, various methods have been proposed, such as parasitic decoupling elements and neutralization line technology, which play a key role in suppressing mutual coupling. However, these methods occupy too much space inside the mobile terminal device, which is not conducive to the miniaturization of the terminal system.

[0010] With the miniaturization of mobile terminal systems, the miniaturization of MIMO antennas has become a research hotspot and trend.

[0011] For miniaturization of MIMO antennas, most MIMO antenna elements in MIMO antenna systems use single-port antenna elements. The first approach is to directly reduce the size of the MIMO antenna itself, which can be achieved through techniques such as slotting and zigzag lines. However, this makes the antenna structure more complex, and miniaturization using these techniques within a limited space will result in a narrower antenna bandwidth and reduced efficiency. Summary of the Invention

[0012] To overcome the shortcomings of the prior art, the present invention aims to provide a dual-port antenna for zero-headroom mobile terminals. It employs a multi-port antenna design, with two radio frequency ports jointly exciting the same antenna radiator. A coupling gap is introduced on the radiator to reduce its size, resulting in an integrated antenna pair with a low VSWR. An LC series resonant circuit is introduced between the radiator and the metal ground plane at the center, maintaining high isolation between the two radio frequency ports. The antenna of this invention has no headroom area between it and the metal ground plane, making it applicable to zero-headroom mobile terminal devices. It features high isolation and a compact structure.

[0013] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0014] A dual-port antenna for a zero-headroom mobile terminal includes a horizontal dielectric substrate 3, vertical dielectric substrates 2 on both sides of the horizontal dielectric substrate 3, a radiator 1 on the inner surface of the vertical dielectric substrate 2, a first port feed network 5 and a second port feed network 6 symmetrically arranged at both ends of the radiator 1 and on the upper surface of the horizontal dielectric substrate 3, and a metal ground plate 4 etched on the back of the horizontal dielectric substrate 3.

[0015] The radiator 1 is connected to the metal floor 4.

[0016] The radiator 1 includes a resonant antenna 11, with metal-coupled microstrip lines 12 at both ends of the resonant antenna 11 and an LC circuit 13 at the middle position of the resonant antenna 11, which is connected to the metal ground plane 4.

[0017] The resonant antenna 11 is shaped like a "Π", and the metal-coupled microstrip line 12 is shaped like a "U".

[0018] The first port feed network 5 includes a first feed microstrip line 51, one end of which is connected to the radiator 1, and the other end of which is provided with a first port feed point 52, which is connected to a first coaxial line 91; the second port feed network 6 includes a second port feed microstrip line 61, one end of which is connected to the radiator 1, and the other end of which is provided with a second port feed point 62, which is connected to a second coaxial line 92.

[0019] The first coaxial cable 91 is connected to a first pad 81 at the end near the first port power supply point 52. The first pad 81 is connected to the metal ground plane 4 through a first metallized via 71. The second coaxial cable 92 is connected to a second pad 82 at the end near the second port power supply point 62. The second pad 82 is connected to the metal ground plane 4 through a second metallized via 72.

[0020] Both the first coaxial cable 91 and the second coaxial cable 92 include an inner core 9-1 and an outer sheath 9-2. The inner core 9-1 is connected to the first port power supply point 52 and the second port power supply point 62, respectively, and the outer sheath 9-2 is connected to the first pad 81 and the second pad 82, respectively.

[0021] The LC circuit 13 is connected to the metal grounding microstrip line 14.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1. Because the present invention adopts a multi-port antenna form, two radio frequency ports jointly excite the same antenna radiator 1. By utilizing the inherent multimode resonance characteristics of the antenna, the antenna element can ensure broadband radiation performance even under zero clearance conditions. Furthermore, the introduction of coupling gaps on the radiator 1 reduces the size of the antenna radiator 1, and the integrated antenna pair has a low standing wave ratio.

[0024] 2. This invention introduces an LC series resonant circuit between the radiator 1 and the metal ground plane 4 at the middle position, maintaining a high isolation of over 15dB between the two RF ports. Because the number of MIMO antenna system ports is not reduced, and a high isolation is maintained between the antenna ports, the channel capacity of the MIMO system remains consistent with that of a traditional MIMO system. Since there is no clearance area between the antenna and the metal ground plane, this invention can be applied to mobile terminal devices with zero clearance.

[0025] 3. The antenna unit proposed in this invention has only one radiator, but the antenna has two radio frequency ports. The proposed antenna can not only be used as an antenna on its own, but can also be used to form a MIMO antenna system.

[0026] 4. The antenna unit proposed in this invention has a compact structure, which can realize a MIMO antenna system with more ports and achieve a high-performance multi-antenna system in a limited space.

[0027] 5. The capacitor connected at the midpoint of the antenna of the present invention and the metal ground microstrip line 14 form a distributed LC parallel resonant circuit between the two ports to suppress the coupling between the two ports. Without adding an additional decoupling structure, the high isolation between the two radio frequency ports can be guaranteed by introducing a distributed LC parallel resonant circuit, which is beneficial to the miniaturization of mobile terminal devices.

[0028] 6. To address the antenna requirements of zero-clearance terminal carriers and further reduce the lateral size of the antennas, this invention adopts a combination of on-frame antennas and internal antennas, with the two antennas sharing a single radiation aperture area. In this case, the lateral size of the antenna pair of this invention (19mm) is reduced compared to the lateral size of the prior art (30mm). Furthermore, this invention only introduces a neutralization line within the radiation aperture area to achieve higher isolation (the isolation of this invention reaches more than 13dB, while the prior art only reaches 10.5dB), without introducing any additional decoupling structures. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the overall structure of the dual-port antenna of the present invention.

[0030] Figure 2 This is a detailed view of the radiator 1 of the dual-port antenna of the present invention.

[0031] Figure 3 This is a top view of the dual-port antenna of the present invention.

[0032] Figure 4 This is a detailed view of the coaxial line 9 of the dual-port antenna of the present invention.

[0033] Figure 5 This is the S-parameter diagram of the dual-port antenna simulation of the present invention.

[0034] Figure 6 This is the radiation efficiency of the dual-port antenna simulation of this invention.

[0035] The components are: 1. Radiator; 2. Vertical dielectric substrate; 3. Horizontal dielectric substrate; 4. Metal ground plane; 5. First port feed network; 51. First port feed microstrip line; 52. First port feed point; 6. Second port feed network; 61. Second port feed microstrip line; 62. Second port feed point; 71. First metallized via; 72. Second metallized via; 81. First pad; 82. Second pad; 91. First coaxial line; 92. Second coaxial line; 9-1. Coaxial line inner core; 9-2. Coaxial line outer sheath; 11. Resonant antenna; 12. Metal-coupled microstrip line; 13. LC circuit; 14. Metal-grounded microstrip line. Detailed Implementation

[0036] The technical solution of the present invention will now be described in detail with reference to the accompanying drawings.

[0037] The purpose of this invention is to solve the problem of maintaining high isolation and good radiation performance between ports in a dual-port MIMO antenna system for mobile terminals under the conditions of zero clearance and no need for additional decoupling structures.

[0038] like Figure 1As shown, a dual-port antenna for a zero-headroom mobile terminal includes a horizontal dielectric plate 3, vertical dielectric plates 2 on both sides of the horizontal dielectric plate 3, a radiator 1 on the inner surface of the vertical dielectric plate 2, and a first port feed network 5 and a second port feed network 6 symmetrically arranged at both ends of the radiator 1 and on the upper surface of the horizontal dielectric plate 3, respectively.

[0039] Vertical dielectric plate 2 represents the phone frame, horizontal dielectric plate 3 represents the phone motherboard, radiator 1 is printed on the inner surface of vertical dielectric plate 2, first port feed network 5 and second port feed network 6 of dual-port antenna are printed on the upper surface of horizontal dielectric plate 3, and metal ground plate 4 is etched on the back of horizontal dielectric plate 3.

[0040] like Figure 2 As shown, the radiator 1 includes a resonant antenna 11, with metal-coupled microstrip lines 12 at both ends of the resonant antenna 11 and an LC circuit 13 at the middle position of the resonant antenna 11. The LC circuit 13 is connected to the metal grounding microstrip line 14.

[0041] The resonant antenna 11 is shaped like a "Π", and the metal-coupled microstrip line 12 is shaped like a "U".

[0042] The present invention is a dual-port antenna with high isolation characteristics and compact structure applicable to zero-headroom mobile terminals. It consists of a radiator 1, a first port feed network 5, and a second port feed network 6. The radiator 1 has an inverted U-shaped structure, and slot coupling structures, namely metal-coupled microstrip lines 12, are symmetrically introduced on both sides of the structure. The slot coupling structure has a U-shape.

[0043] The antenna radiator has a symmetrical structure. The first port feed network 5 and the second port feed network 6 that feed the radiator are connected to both sides of the radiator 1 and are symmetrically distributed.

[0044] The radiator 1 is bonded to the metal floor 4, creating a zero-headroom environment.

[0045] like Figure 3 As shown, the first port feed network 5 of the dual-port antenna is composed of a first port feed microstrip line 51, a first port feed point 52, and a first coaxial line 91, wherein the first port feed microstrip line 51 is welded together with the radiator 1. The second port feed network 6 of the dual-port antenna is composed of a second port feed microstrip line 61, a second port feed point 62, and a coaxial line 9, wherein the second port feed microstrip line 61 is welded together with the radiator 1.

[0046] The first port feed network 5 and the second port feed network 6 have the same structure.

[0047] The first coaxial cable 91 is connected to a first pad 81 at the end near the first port power supply point 52. The first pad 81 is connected to the metal ground plane 4 through a first metallized via 71. The second coaxial cable 92 is connected to a second pad 82 at the end near the second port power supply point 62. The second pad 82 is connected to the metal ground plane 4 through a second metallized via 72.

[0048] like Figure 4 As shown, both the first coaxial cable 91 and the second coaxial cable 92 include an inner core 9-1 and an outer sheath 9-2. The inner core 9-1 is connected to the first port power supply point 52 and the second port power supply point 62, respectively, and the outer sheath 9-2 is connected to the first pad 81 and the second pad 82, respectively.

[0049] like Figure 5 As shown, the antenna has a -6dB impedance bandwidth of 3.34-3.7GHz, exhibiting good radiation performance; the isolation between the two ports is greater than 15dB across the entire frequency band, demonstrating high isolation characteristics.

[0050] like Figure 6 As shown, the overall simulation efficiency of both ports is greater than 75%.

Claims

1. A dual-port antenna for a zero-headroom mobile terminal, comprising a horizontal dielectric substrate (3), wherein vertical dielectric substrates (2) are respectively provided on both sides of the horizontal dielectric substrate (3), characterized in that: The inner surface of the vertical dielectric plate (2) is provided with a radiator (1), and the two ends of the radiator (1) and the upper surface of the horizontal dielectric plate (3) are respectively symmetrically provided with a first port feed network (5) and a second port feed network (6), and the back of the horizontal dielectric plate (3) is etched with a metal floor (4). The radiator (1) is connected to the metal floor (4); The radiator (1) includes a resonant antenna (11), with metal-coupled microstrip lines (12) at both ends of the resonant antenna (11) and an LC circuit (13) at the middle position of the resonant antenna (11). The LC circuit (13) is connected to the metal ground plane (4). A capacitor connected at the midpoint of the antenna and the metal ground microstrip line (14) form a distributed LC parallel resonant circuit between the two ports to suppress the coupling between the two ports. The resonant antenna (11) is shaped like a "Π", and the metal-coupled microstrip line (12) is shaped like a "U".

2. The dual-port antenna for a zero-clearance mobile terminal according to claim 1, characterized in that: The first port feed network (5) includes a first port feed microstrip line (51), one end of which is connected to a radiator (1), and the other end of which is provided with a first port feed point (52), which is connected to a first coaxial line (91); the second port feed network (6) includes a second port feed microstrip line (61), one end of which is connected to a radiator (1), and the other end of which is provided with a second port feed point (62), which is connected to a second coaxial line (92).

3. A dual-port antenna for a zero-clearance mobile terminal according to claim 2, characterized in that: The first coaxial cable (91) is connected to a first pad (81) at the end near the first port power supply point (52), and the first pad (81) is connected to the metal ground plane (4) through a first metallized via (71); the second coaxial cable (92) is connected to a second pad (82) at the end near the second port power supply point (62), and the second pad (82) is connected to the metal ground plane (4) through a second metallized via (72).

4. A dual-port antenna for a zero-clearance mobile terminal according to claim 3, characterized in that: The first coaxial cable (91) and the second coaxial cable (92) each include a coaxial cable inner core (9-1) and a coaxial cable outer skin (9-2). The inner core (9-1) is connected to the first port power supply point (52) and the second port power supply point (62) respectively, and the coaxial cable outer skin (9-2) is connected to the first pad (81) and the second pad (82) respectively.

5. A dual-port antenna for a zero-clearance mobile terminal according to claim 1, characterized in that: The LC circuit (13) is connected to the metal grounding microstrip line (14) via the metal grounding microstrip line (4).

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