A compact MIMO antenna system based on connecting wires

Abstract

This invention discloses a compact MIMO antenna system based on a connecting line, comprising a ground plane, a first antenna, a second antenna, and a connecting line disposed outside the first and second antennas. The outer ends of the first antenna and the second antenna are respectively connected to the ground plane. One end of the connecting line is connected to a non-end portion of the first antenna, and the other end of the connecting line is connected to a non-end portion of the second antenna. The compact MIMO antenna system based on the connecting line of this invention features a compact antenna structure, small antenna element size, and close element spacing, achieving a highly integrated, highly compact, highly isolated, and compatible MIMO antenna system with multiple antenna types. This invention is applicable to various wireless communication devices, especially to the application of large-scale arrays in terminal devices.

Description

Technical Field

[0001] The invention relates to the technical field of communication antennas, and specifically proposes a coupling reduction technology of a compact MIMO antenna system based on connecting wires, which can be used for various wireless communication devices. Background Art

[0002] Antennas have become an essential device in various wireless devices to transmit and receive electromagnetic wave signals. MIMO (Multiple-Input Multiple-Output) technology uses multiple antenna devices to transmit and receive simultaneously, which can greatly improve the wireless transmission rate without increasing the transmission power or increasing the working spectrum. It is one of the core technologies of the fourth-generation mobile communication and fifth-generation communication systems. In order to ensure excellent MIMO characteristics, high isolation or low coupling between antennas must be achieved to reduce the correlation between antennas. However, due to the limited space of modern wireless devices and the small antenna spacing, the signal interference between antennas becomes larger, which seriously affects the performance of the MIMO system. The traditional method relies on increasing the distance between antennas to achieve high isolation, which makes it difficult to integrate more antenna devices into the wireless device, and therefore cannot meet the current demand for high transmission rate transmission.

[0003] Especially with the layout and promotion of the fifth generation communication system, large-scale antenna arrays have become a trend, and the demand for compact MIMO antenna systems is increasing. The existing technology mainly improves the isolation between antennas by introducing parasitic resonance, introducing decoupling networks, and using orthogonal modes.

[0004] On the one hand, introducing a new parasitic structure between two antennas is one of the most common methods to improve isolation. The parasitic structure can generate a coupling route with opposite phase to offset the original coupling between the antennas, thereby improving antenna isolation. The types of parasitic structures can be slots, rings, strips, suspended structures, etc. However, this method requires the introduction of additional structures, which occupies a large space and is not conducive to the miniaturization design of the antenna. In addition, this method is difficult to achieve a highly compact MIMO antenna system.

[0005] On the other hand, the decoupling network usually uses lumped element circuits or neutralization lines to offset the coupling between antennas, which can effectively realize compact MIMO antenna design. However, this method requires more components or occupies a larger circuit area, and is currently only applicable to monopole antennas or inverted F antennas.

[0006] In addition, placing antennas orthogonally or exciting orthogonal current modes can well achieve high isolation and compact MIMO antenna systems without the need for additional decoupling structures or circuits. However, this method requires a larger antenna size, making it difficult to achieve integration and miniaturization of the MIMO antenna system.

[0007] The above-mentioned prior arts either cannot realize a compact MIMO system, or have a relatively complex decoupling structure, or have great application limitations, or have a relatively large antenna size.

[0008] Therefore, it is necessary to propose a simple and efficient decoupling technology that is compatible with a variety of different antenna types, thereby avoiding the time-consuming case analysis and debugging in traditional methods and saving development cycles; it is necessary to propose a highly integrated, highly compact, and highly isolated MIMO antenna system. Summary of the invention

[0009] In order to solve the shortcomings of the prior art, the present invention provides a coupling reduction technology based on connecting wires, which has the characteristics of compact antenna structure, small antenna unit size, close unit spacing, etc., and realizes a MIMO antenna system that is highly integrated, highly compact, has high isolation, and is compatible with multiple antenna types. The invention can be applied to various wireless communication devices, especially to the application of large-scale arrays in terminal devices.

[0010] The technical effect to be achieved by the present invention is realized through the following scheme: a compact MIMO antenna system based on connecting wires, comprising a ground plate, a first antenna, a second antenna, and a connecting wire arranged outside the first antenna and the second antenna, wherein the outer end of the first antenna and the outer end of the second antenna are respectively connected to the ground plate, one end of the connecting wire is connected to a non-end of the first antenna and the other end of the connecting wire is connected to a non-end of the second antenna.

[0011] Preferably, the first antenna and the second antenna are arranged opposite to each other, the first antenna includes a first feed and a first resonant wire, and the outer end of the first resonant wire is connected to the ground plate; the second antenna includes a second feed and a second resonant wire, and the outer end of the second resonant wire is connected to the ground plate; the connecting line includes a connecting wire having a first inductance element, one end of the connecting wire is connected to the non-end of the first resonant wire, and the other end of the connecting wire is connected to the non-end of the second resonant wire.

[0012] Preferably, the other end of the first resonant wire is disconnected or electrically connected to a ground plate via a first capacitor, and the inner end of the second resonant wire is disconnected or electrically connected to a ground plate via a second capacitor.

[0013] Preferably, the outer end of the first resonant wire is connected to a first feed, and the first antenna is directly fed through the first feed connection ground plate; the outer end of the second resonant wire is connected to a second feed, and the second antenna is directly fed through the second feed connection ground plate.

[0014] Preferably, the first resonant wire includes a second inductor element, and the second resonant wire includes a third inductor element.

[0015] Preferably, the first resonant wire includes a first branch, one end of the first branch is connected to the first resonant wire, and the other end of the first branch is disconnected; the second resonant wire includes a second branch, one end of the second branch is connected to the second resonant wire, and the other end of the second branch is disconnected.

[0016] Preferably, the disconnection setting end of the first branch is electrically connected to the ground plate through a first component, and the disconnection setting end of the first branch is electrically connected to the ground plate through a second component.

[0017] Preferably, the first antenna also includes a first excitation wire, one end of which is connected to the first resonant wire or is disconnected, and the other end of the first excitation wire is connected to the first feed, and the first feed is connected to the ground plane; the second antenna also includes a second excitation wire, one end of which is connected to the second resonant wire or is disconnected, and the other end of the second excitation wire is connected to the second feed, and the second feed is connected to the ground plane.

[0018] Preferably, the first excitation wire includes a third component, and the second excitation wire includes a fourth component.

[0019] Preferably, it further comprises a clearance area, which is a groove hollowed out on the side of the ground plate, and the first antenna and the second antenna are both arranged in the clearance area.

[0020] The present invention has the following advantages:

[0021] 1) Different from the existing technology, the connecting wire proposed in the present invention is a simple and efficient coupling reduction technology, which is compatible with different antenna types and constitutes a compact MIMO antenna system with high isolation, and has a broader application prospect;

[0022] 2) The present invention realizes a highly compact MIMO antenna system, which has the characteristics of compact structure, small unit size, and close unit spacing while achieving high isolation and low correlation. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1a It is a structural schematic diagram of a first specific implementation scheme of a compact MIMO antenna system based on connecting wires in Example 1 of the present invention;

[0024] Figure 1b It is a structural schematic diagram of a second specific implementation scheme of a compact MIMO antenna system based on connecting wires in Example 1 of the present invention;

[0025] Figure 1c It is a structural schematic diagram of a third specific implementation scheme of a compact MIMO antenna system based on connecting wires in Example 1 of the present invention;

[0026] Figure 2a It is a structural schematic diagram of a first specific implementation scheme of a compact MIMO antenna system based on connecting wires in the second embodiment of the present invention;

[0027] Figure 2b It is a structural schematic diagram of a second specific implementation scheme of a compact MIMO antenna system based on connecting wires in the second embodiment of the present invention;

[0028] Figure 2c It is a structural schematic diagram of a third specific implementation scheme of a compact MIMO antenna system based on connecting wires in the second embodiment of the present invention;

[0029] Figure 3a A schematic diagram of a compact MIMO antenna system based on a connecting line composed of different excitation loops (Example 1) in the present invention is shown;

[0030] Figure 3b A schematic diagram of a compact MIMO antenna system based on a connecting line composed of different excitation loops (Example 2) in the present invention is shown;

[0031] Figure 3c A schematic diagram of a compact MIMO antenna system based on a connecting line composed of different excitation loops (Example 3) in the present invention is shown;

[0032] Figure 4a A schematic diagram of a compact MIMO antenna system based on a connecting line composed of different resonant loops (Example 1) in the present invention is shown;

[0033] Figure 4b A schematic diagram of a compact MIMO antenna system based on a connecting line composed of different resonant loops (Example 2) in the present invention is shown;

[0034] Figure 4c A schematic diagram of a compact MIMO antenna system based on a connecting line composed of different resonant loops (Example 3) in the present invention is shown;

[0035] Figure 5 The S-parameter diagram of a compact MIMO antenna system based on a connecting line in a single-frequency mode of the present invention is shown;

[0036] Figure 6 An S-parameter diagram of a compact MIMO antenna system based on a connecting line in a dual-frequency mode in the present invention is shown. DETAILED DESCRIPTION

[0037] The present invention is described in detail below in conjunction with the accompanying drawings and embodiments, examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0038] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0039] In addition, the terms "first", "second", and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second", and "third" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0040] In the present invention, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix", "set" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] By deeply studying the coupling principle of MIMO antennas, the present invention proposes a compact MIMO antenna system based on connecting wires. The present invention is a simple and efficient coupling reduction technology that is compatible with a variety of antenna types to form a compact MIMO antenna system, which has a wider application prospect.

[0042] Embodiment 1

[0043] FIG. 1 shows a schematic structural diagram of a compact MIMO antenna system based on connecting wires in Embodiment 1 of the present invention.

[0044] As shown in FIG1 , a compact MIMO antenna system based on a connecting line includes a ground plate 102, a first antenna 110a, a second antenna 110b, and a connecting line 120 disposed outside the first antenna 110a and the second antenna 110b, wherein the outer end of the first antenna 110a and the outer end of the second antenna 110b are respectively connected to the ground plate 102, one end of the connecting line 120 is connected to a non-end of the first antenna 110a, and the other end of the connecting line 120 is connected to a non-end of the second antenna 110b. It should be understood that the end referred to in the embodiment of the present invention represents the end position of one end of the line, the other end represents the end position opposite to the end, and the non-end connection referred to represents not being connected to the end points of both ends of the line.

[0045] like Figure 1a As shown, the first antenna 110a includes a first feed 111a, a first excitation wire 112a and a first resonant wire 113a. The first resonant wire 113a is L-shaped, and the outer end of the first resonant wire 113a is connected to the ground plate 102, and the inner end of the first resonant wire 113a is disconnected. The ground plate 102 is laid on a printed circuit board. The first resonant wire 113a serves as a resonant circuit of the first antenna 110a, and its wire length is about a quarter of a wavelength, which determines the resonant frequency of the first antenna 110a. One end of the first excitation wire 112a is connected to the first resonant wire 113a, and the other end of the first excitation wire 112a is connected to the first feed 111a, and the first feed 111a is connected to the ground plate 102. The first excitation wire 112a serves as an excitation circuit of the first antenna 110a to control the impedance matching of the first antenna 110a. It should be noted that the first excitation wire 112a can be connected to the end of the first vibration wire 113a connected to the grounding plate 102, or can be connected to any non-end position of the first vibration wire 113a, but cannot be connected to the disconnected end of the first vibration wire 113a.

[0046] like Figure 1a As shown, the second antenna 110b is arranged opposite to the first antenna 110a, and can also be arranged as follows Figure 1a The mirror symmetry setting shown in the figure can also be set without mirror symmetry. Figure 1aThe above is only used as an example and should not be used as a limitation of the present invention. The second antenna 110b includes a second feed 111b, a second excitation wire 112b and a second resonant wire 113b. The second resonant wire 113b is L-shaped, the outer end of the second resonant wire 113b is connected to the ground plate 102, the inner end of the second resonant wire 113b is disconnected, and the disconnected end of the second resonant wire 113b faces the disconnected end of the first resonant wire 113a. The second resonant wire 113b serves as a resonant circuit of the second antenna 110b, and its wire length is about a quarter of a wavelength, which determines the resonant frequency of the second antenna 110b. One end of the second excitation wire 112b is connected to the second resonant wire 113b, and the other end of the second excitation wire 112b is connected to the second feed 111b, and the second feed 111b is connected to the ground plate 102. The second excitation wire 112b serves as an excitation circuit of the second antenna 110b to control the impedance matching of the second antenna 110b. It should be noted that the second excitation wire 112b can be connected to the end of the second resonance wire 113b connected to the ground plate 102, or to any non-end position of the second resonance wire 113b, but cannot be connected to the disconnected end of the second resonance wire 113b.

[0047] According to an embodiment of the present invention, the first antenna 110a and the second antenna 110b are arranged adjacent to each other, and the distance between them is preferably less than one tenth of a wavelength, forming a compact MIMO antenna system based on a connecting line. Since the distance between the antennas is very small and they share a ground plane, strong electromagnetic coupling will occur between the antennas, which seriously affects the performance of the MIMO system. Therefore, a simple and efficient connecting line is used in the present invention to improve the isolation between the antennas and reduce the correlation between the antennas.

[0048] like Figure 1a As shown, the connecting wire 120 includes a connecting wire 121 having a first inductance element 122. One end of the connecting wire 121 is connected to the non-end of the first resonant wire 113a, and the other end of the connecting wire 121 is connected to the non-end of the second resonant wire 113b. Therefore, the connecting wire 120 bridges the first resonant wire 113a and the second resonant wire 113b, and covers the disconnected end of the first resonant wire 113a and the disconnected end of the second resonant wire 113b, that is, the disconnected end of the first resonant wire 113a and the disconnected end of the second resonant wire 113b are both located inside the connecting wire 120. The connecting wire 121 includes a first inductance element 122, and the inductance element has an inductance component, which can be a lumped element, such as a chip inductor, a chip resistor, etc., or a distributed element, such as a wire, a coil, etc. In addition, the inductance element can be composed of a single inductance element, or can be composed of a plurality of inductance elements connected to each other.

[0049] According to the embodiment of the present invention, the connecting line 120 transfers part of the energy of the first antenna 110a to the second antenna 110b, thereby compensating the original coupling between the first antenna 110a and the second antenna 110b. By adjusting the connection position of the connecting line 120 on the first resonant wire 113a and the second resonant wire 113b, as well as the current length of the connecting line 120 and the inductance value of the first inductor element 122, the phase and magnitude of the current in the connecting line 120 can be controlled, thereby offsetting the mutual coupling between the antennas and generating high isolation.

[0050] Figure 1b The deformation structure of the first embodiment of the present invention is shown.

[0051] like Figure 1b As shown, the first resonant conductor 113a is in a vertically bent hook shape, with the outer end connected to the ground plate 102 and the inner end disconnected, with the disconnected end being close to the ground plate 102, thereby forming a distributed capacitor between the ground plate 102 and the first resonant conductor 113a, which can effectively reduce the length of the first resonant conductor 113a and achieve miniaturization of the antenna. The second resonant conductor 113b is in a vertically bent hook shape that is mirror-symmetrical to the first resonant conductor 113a, with the outer end of the second resonant conductor 113b connected to the ground plate 102 and the inner end of the second resonant conductor 113b disconnected, with the disconnected end being close to the ground plate 102, thereby forming a distributed capacitor between the ground plate 102 and the second resonant conductor 113b, which can effectively reduce the length of the second resonant conductor 113b and achieve miniaturization of the antenna. Other circuit structures and Figure 1a Same as in.

[0052] Figure 1c Another variation structure of the first embodiment of the present invention is shown.

[0053] like Figure 1c As shown, the disconnected end of the first resonant wire 113a is electrically connected to the ground plate 102 through the first capacitor element 114a, so that the length of the first resonant wire 113a can be greatly reduced, and the antenna can be miniaturized. The disconnected end of the second resonant wire 113b is electrically connected to the ground plate 102 through the second capacitor element 114b, so that the length of the second resonant wire 113b can be greatly reduced, and the antenna can be miniaturized. Other circuit structures are similar to Figure 1a Therefore, the connection line 120 covers the first capacitor element 114 a and the second capacitor element 114 b , that is, the first capacitor element 114 a and the second capacitor element 114 b are located inside the connection line 120 .

[0054] According to an embodiment of the present invention, the capacitor element has a capacitance component, which can be a lumped element, such as a chip capacitor, a varactor diode, a transistor, etc., or a distributed element, such as a parallel wire, a transmission line, etc. In addition, the capacitor element can be composed of a single capacitor element, or can be composed of a plurality of capacitor elements connected to each other. In order to obtain a certain specific capacitance, a combination of a plurality of elements can be used to replace the capacitor element, for example, the capacitor element can be replaced by a combination structure of a capacitor element and an inductor element.

[0055] Embodiment 2

[0056] FIG. 2 is a schematic diagram of the structure of a compact MIMO antenna system based on connecting wires in Embodiment 2 of the present invention.

[0057] As shown in FIG2 , a compact MIMO antenna system based on a connecting line includes a ground plate 102, a clearance area 204, a first antenna 210a, a second antenna 210b, and a connecting line 220 disposed outside the first antenna 210a and the second antenna 210b, wherein the outer end of the first antenna 210a and the outer end of the second antenna 210b are respectively connected to the ground plate 102, one end of the connecting line 220 is connected to the non-end of the first antenna 210a, and the other end of the connecting line 220 is connected to the non-end of the second antenna 210b. The first antenna 210a and the second antenna 210b are both disposed in the clearance area 204. The clearance area 204 is a groove hollowed out on the side of the ground plate 102.

[0058] like Figure 2a As shown, the first antenna 210a includes a first feed 211a, a first excitation wire 212a and a first resonant wire 213a. The first resonant wire 213a is in a straight line, with the outer end connected to the ground plate 102 and the inner end disconnected. The first resonant wire 213a serves as a resonant circuit of the first antenna 210a, and its wire length is about a quarter of a wavelength, which determines the resonant frequency of the first antenna 210a. One end of the first excitation wire 212a is connected to the first resonant wire 213a, and the other end of the first excitation wire 212a is connected to the first feed 211a, and the first feed 211a is connected to the ground plate 102. The first excitation wire 212a serves as an excitation circuit of the first antenna 210a to control the impedance matching of the first antenna 210a.

[0059] The second antenna 210b is arranged opposite to the first antenna 210a. The second antenna 210b includes a second feed 211b, a second excitation wire 212b and a second resonant wire 213b. The second resonant wire 213b is in a straight line, with an outer end connected to the ground plate 102, and an inner end disconnected, with the disconnected end facing the disconnected end of the first resonant wire 213a. The second resonant wire 213b serves as a resonant circuit of the second antenna 210b, and its wire length is approximately one-quarter of a wavelength, which determines the resonant frequency of the second antenna 210b. One end of the second excitation wire 212b is connected to the second resonant wire 213b, and the other end of the second excitation wire 212b is connected to the second feed 211b, and the second feed 211b is connected to the ground plate 102. The second excitation wire 212b serves as an excitation circuit of the second antenna 210b to control the impedance matching of the second antenna 210b.

[0060] The connection line 220 is composed of a connection conductor 221 including a first inductance element 222, and is arranged outside the first antenna 210a and the second antenna 210b. One end of the connection conductor 221 is connected to the non-end of the first resonance conductor 213a, and the other end of the connection conductor 221 is connected to the non-end of the second resonance conductor 213b. Therefore, the connection line 220 covers the disconnected end of the first resonance conductor 213a and the disconnected end of the second resonance conductor 213b, that is, the disconnected end of the first resonance conductor 213a and the disconnected end of the second resonance conductor 213b are located inside the connection line 220. The connection conductor 221 includes a first inductance element 222, and can control the effective current length of the connection line 220.

[0061] Figure 2b The deformation structure of the second embodiment of the present invention is shown.

[0062] like Figure 2b As shown, the first resonant conductor 213a in the first antenna 210a is in a horizontally folded hook shape, with the outer end connected to the ground plate 102 and the inner end disconnected, and the disconnected end is arranged close to the ground plate 102, so that a distributed capacitor is formed between the ground plate 102 and the first resonant conductor 213a, thereby effectively reducing the length of the first resonant conductor 213a and realizing miniaturization of the antenna. The second resonant conductor 213b in the second antenna 210b is in a horizontally folded hook shape, with the outer end connected to the ground plate 102 and the inner end disconnected, and the disconnected end is arranged close to the ground plate 102, so that a distributed capacitor is formed between the ground plate 102 and the fourth conductor 213b, thereby effectively reducing the length of the second resonant conductor 213b and realizing miniaturization of the antenna. Other circuit structures are similar to Figure 2a Same as in.

[0063] Figure 2c The deformation structure of the second embodiment of the present invention is shown.

[0064] like Figure 2c As shown, the disconnected end of the first resonant wire 213a is electrically connected to the ground plate 102 through the first capacitor element 214a, so that the length of the first resonant wire 213a can be greatly reduced, and the antenna can be miniaturized. The disconnected end of the second resonant wire 213b is electrically connected to the ground plate 102 through the second capacitor element 214b, so that the length of the second resonant wire 213b can be greatly reduced, and the antenna can be miniaturized. Other circuit structures are similar to Figure 2a Therefore, the connection line 220 covers the first capacitor element 214 a and the second capacitor element 214 b , that is, the first capacitor element 214 a and the second capacitor element 214 b are located inside the connection line 220 .

[0065] FIG. 3 shows a schematic diagram of a compact MIMO antenna system based on connecting wires formed by different excitation loops in the present invention.

[0066] As shown in FIG3 , a compact MIMO antenna system based on connecting wires includes a ground plane 102, a first antenna 310a, a second antenna 310b, and a connecting wire 320 arranged outside the first antenna 310a and the second antenna 310b, wherein the outer end of the first antenna 310a and the outer end of the second antenna 310b are respectively connected to the ground plane 102, one end of the connecting wire 320 is connected to a non-end of the first antenna 310a, and the other end of the connecting wire 320 is connected to a non-end of the second antenna 310b.

[0067] like Figure 3a As shown, the first antenna 310a includes a first feed 311a, a first excitation wire 312a and a first resonant wire 313a. One end of the first excitation wire 312a is connected to the first resonant wire 313a, and the other end is connected to the first feed 311a, and the first feed 311a is connected to the ground plate 102. The first excitation wire 312a includes a third component 314a, and the third component 314a can be used to simply control the impedance matching of the first antenna 310a.

[0068] The second antenna 310b is arranged opposite to the first antenna 310a. The second antenna 310b includes a second feeder 311b, a second excitation wire 312b and a second resonant wire 313b. One end of the second excitation wire 312b is connected to the second resonant wire 313b, and the other end is connected to the second feeder 311b. The second feeder 311b is connected to the ground plate 102. The second excitation wire 312b includes a fourth component 314b, which can be used to simply control the impedance matching of the second antenna 310b. Other circuit structures are similar to Figure 1a Same as in.

[0069] According to an embodiment of the present invention, the component may be a wire, an inductor or a capacitor. The inductor has an inductance component and may be a lumped element, such as a chip inductor, a chip resistor, etc., or a distributed element, such as a wire, a coil, etc. Similarly, the inductor may be composed of a single inductor or a plurality of inductors connected to each other.

[0070] like Figure 3b As shown, the first excitation wire 312a in the first antenna 310a is L-shaped, one end is disconnected, and the other end is connected to the first feed 311a. The second excitation wire 312b in the second antenna 310b is L-shaped, one end is disconnected, and the other end is connected to the second feed 311b. The wire lengths of the first excitation wire 312a and the second excitation wire 312b can be used to control the impedance matching of the first antenna 310a and the second antenna 310b. Other circuit structures are similar to Figure 1a same.

[0071] like Figure 3c As shown, the first antenna 310a includes a first feed 311a and a first resonant wire 313a. The first antenna 310a is directly fed by connecting to the ground plate 102 through the first feed 311a. The outer end of the first resonant wire 313a is connected to the first feed 311a, and the inner end is disconnected. The second antenna 310b includes a second feed 311b and a second resonant wire 313b. The second antenna 310b is directly fed by connecting to the ground plate 102 through the second feed 311b. The outer end of the second resonant wire 313b is connected to the second feed 311b, and the inner end is disconnected. Other circuit structures are similar to Figure 1a same.

[0072] According to the embodiments of the present invention, the excitation circuit of the present invention may have different forms of expression according to its type, position, connection method, etc., and any conventional structure of the excitation circuit in the prior art may be used to feed the antenna. Therefore, the present invention does not impose specific restrictions on the specific structure, type and connection method of the excitation circuit.

[0073] FIG. 4 shows a schematic diagram of a compact MIMO antenna system based on connecting wires formed by different resonant loops according to the present invention.

[0074] As shown in FIG4 , a compact MIMO antenna system based on connecting wires includes a first antenna 410a, a second antenna 410b, and a connecting wire 420 arranged outside the first antenna 410a and the second antenna 410b, wherein the outer end of the first antenna 410a and the outer end of the second antenna 410b are respectively connected to a ground plane 102, one end of the connecting wire 420 is connected to a non-end of the first antenna 410a, and the other end of the connecting wire 420 is connected to a non-end of the second antenna 410b.

[0075] like Figure 4a As shown, the first antenna 410a includes a first feed 411a, a first excitation wire 412a and a first resonant wire 413a. The first resonant wire 413a is L-shaped, with the outer end connected to the ground plate 102 and the inner end disconnected. The first resonant wire 413a includes a second inductor 414a, so that the length of the first resonant wire 413a can be effectively reduced, thereby realizing the miniaturization of the antenna.

[0076] The second antenna 410b is disposed opposite to the first antenna 410a. The second antenna 410b includes a second feeder 411b, a second excitation wire 412b, and a second resonant wire 413b. The second resonant wire 413b is L-shaped, with the outer end connected to the ground plate 102 and the inner end disconnected. The second resonant wire 413b includes a third inductor 414b, thereby effectively reducing the length of the second resonant wire 413b and realizing miniaturization of the antenna. Other circuit structures are similar to Figure 1a same.

[0077] like Figure 4b As shown, the first resonant wire 413a in the first antenna 410a includes a first branch 415a, one end of the first branch 415a is connected to the first resonant wire 412a, and the other end of the first branch 415a is disconnected. The first resonant wire 413a including the first branch 145a can generate two resonances to form a dual-frequency antenna. The second resonant wire 413b in the second antenna 410b includes a second branch 145b, one end of the second branch 415b is connected to the second resonant wire 412b, and the other end of the second branch 415b is disconnected. The second resonant wire 413b with the second branch 145b can generate two resonances to form a dual-frequency antenna. Other circuit structures are similar to Figure 1a same.

[0078] like Figure 4cAs shown, the first resonant wire 413a in the first antenna 410a is connected to the first branch 415a, and the disconnected end of the first branch 415a is electrically connected to the ground plane 102 through the first component 416a. The first resonant wire 413a including the first branch 145a can generate two resonances to form a dual-frequency antenna. The second resonant wire 413b in the second antenna 410b is connected to the second branch 415b, and the disconnected end of the second branch 415b is electrically connected to the ground plane 102 through the second component 416b. The second resonant wire 413b with the second branch 145b can generate two resonances to form a dual-frequency antenna. Other circuit structures are similar to Figure 1a same.

[0079] In the above-mentioned embodiments of the present invention, those skilled in the art should understand that the first antenna, the second antenna, the connecting line and the ground plane can be arranged in the same plane or in different planes. All drawings of the embodiments of the present invention take the same plane as an example, which should not be regarded as a limitation.

[0080] As can be seen from the above, the connecting wire of the present invention can effectively reduce the isolation of the compact MIMO antenna system based on the connecting wire. The structures of the first antenna and the second antenna can be the same or different. And there can be many different implementation cases according to different design requirements, antenna structures, antenna types, and installation locations.

[0081] Figure 5 An S-parameter diagram of a compact MIMO antenna system based on a connecting line in a single-frequency mode in the present invention is shown.

[0082] like Figure 5 As shown, the first curve 5a is the reflection coefficient generated by the first antenna, and the second curve 5b is the reflection coefficient generated by the second antenna. The center frequencies of the two antennas are both around 3.5 GHz, and have broadband characteristics. The third curve 5c is the reverse transmission coefficient between the two antennas, which represents the coupling degree between the antennas. It can be seen that the third curve 5c generates a coupling peak and valley within the working frequency band, thereby ensuring a higher isolation degree (above 15 dB) between the antennas. In addition, the radiation efficiency of the compact MIMO antenna is above 80%, and the correlation (ECC) obtained in the simulation is less than 0.1. Therefore, the compact MIMO antenna system based on connecting wires in the present invention has the characteristics of high isolation, good radiation performance, low correlation, etc., and is suitable for the application of MIMO systems.

[0083] Figure 6 An S-parameter diagram of a compact MIMO antenna system based on a connecting line in a dual-frequency mode in the present invention is shown.

[0084] In conjunction with FIG. 4 , it can be seen that the compact MIMO antenna system based on connecting wires in the present invention can generate one or more resonances to achieve a decoupling effect in a single frequency band or multiple frequency bands. Figure 6 As shown, the first curve 6a and the second curve 6b are the reflection coefficients generated by the first antenna and the second antenna, respectively. The two antennas resonate in both the 3.5 GHz and 5.3 GHz frequency bands. The third curve 6c is the reverse transmission coefficient between the antennas, representing the coupling degree between the antennas. It can be seen that the isolation in the two frequency bands is above 12 dB. Therefore, the coupling reduction technology in the present invention is also applicable to a compact MIMO antenna system based on connecting wires in a multi-band mode.

[0085] In summary, compared with the prior art, the above embodiment has the following characteristics:

[0086] 1) The decoupling technology in the present invention can be applied to various types of antennas to form a compact MIMO antenna system based on connecting wires with high isolation, which has the characteristics of compact structure, small unit size, close unit spacing, high isolation, low correlation, etc., and has a wider range of application scenarios.

[0087] 2) The compact MIMO antenna system based on connecting wires in the present invention is applicable not only to a single frequency band but also to multiple frequency bands.

[0088] The above is a preferred embodiment of the present invention and does not impose any form of limitation on the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications are also within the scope of protection of the present invention.

Claims

1. A compact MIMO antenna system based on connecting wires, characterized in that: The invention comprises a ground plate, a first antenna, a second antenna, and a connecting line arranged outside the first antenna and the second antenna, wherein the outer end of the first antenna and the outer end of the second antenna are respectively connected to the ground plate, one end of the connecting line is connected to a non-end of the first antenna, and the other end of the connecting line is connected to a non-end of the second antenna; The first antenna and the second antenna are arranged opposite to each other, the first antenna comprises a first feed and a first resonant wire, the outer end of the first resonant wire is connected to the ground plate, and the inner end of the first resonant wire is disconnected; a distributed capacitor is formed between the ground plate and the first resonant wire; The second antenna includes a second feed and a second resonant wire, the outer end of the second resonant wire is connected to the ground plate, and the inner end of the second resonant wire is disconnected; a distributed capacitor is formed between the ground plate and the second resonant wire.

2. A compact MIMO antenna system based on connecting wires as claimed in claim 1, characterized in that: The connecting line includes a connecting wire having a first inductance element, one end of the connecting wire is connected to the non-end of the first resonant wire, and the other end of the connecting wire is connected to the non-end of the second resonant wire.

3. A compact MIMO antenna system based on connecting wires as claimed in claim 2, characterized in that: The outer end of the first resonant wire is connected to a first feed, and the first antenna is directly fed through the first feed connection ground plate; the outer end of the second resonant wire is connected to a second feed, and the second antenna is directly fed through the second feed connection ground plate.

4. A compact MIMO antenna system based on connecting wires as claimed in claim 2, characterized in that: The first resonant wire includes a second inductance element therein, and the second resonant wire includes a third inductance element therein.

5. A compact MIMO antenna system based on connecting wires as claimed in claim 2, characterized in that: The first resonant wire includes a first branch, one end of the first branch is connected to the first resonant wire, and the other end of the first branch is disconnected; the second resonant wire includes a second branch, one end of the second branch is connected to the second resonant wire, and the other end of the second branch is disconnected.

6. A compact MIMO antenna system based on connecting wires as claimed in claim 5, characterized in that: The disconnection setting end of the first branch is electrically connected to the ground plate through a first component, and the disconnection setting end of the second branch is electrically connected to the ground plate through a second component.

7. A compact MIMO antenna system based on connecting wires as claimed in claim 2, characterized in that: The first antenna also includes a first excitation wire, one end of which is connected to the first resonant wire or is disconnected, and the other end of the first excitation wire is connected to the first feed, and the first feed is connected to the ground plane; the second antenna also includes a second excitation wire, one end of which is connected to the second resonant wire or is disconnected, and the other end of the second excitation wire is connected to the second feed, and the second feed is connected to the ground plane.

8. A compact MIMO antenna system based on connecting wires as claimed in claim 7, characterized in that: The first excitation wire includes a third component, and the second excitation wire includes a fourth component.

9. A compact MIMO antenna system based on connecting wires as claimed in any one of claims 1 to 8, characterized in that: It also includes a clearance area, which is a groove hollowed out on the side of the ground plate, and the first antenna and the second antenna are both configured in the clearance area.

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