CN111403903A - Compact MIMO antenna system - Google Patents

Abstract

The invention discloses a compact MIMO antenna system, comprising a ground plate, a first antenna, a second antenna and a ring decoupling structure, wherein the first antenna and the second antenna are radiators for generating antenna resonance and radiating , the annular decoupling structure is used to decouple the first antenna and the second antenna; the annular decoupling structure is a narrow and long closed-loop structure connected to the ground plate, and the regions on both sides of the long side direction generate strong current distribution and current The mode is opposite, and the weak current distribution is generated in the middle area of the long side direction; the first antenna and the second antenna are arranged adjacently or electrically connected and formed in the middle area of the long side direction of the annular decoupling structure, and the annular decoupling structure is a A simple and efficient decoupling technique, compatible with different antenna types, to form a compact MIMO antenna system with high isolation.

Description

A compact MIMO antenna system

technical field

The present invention relates to the technical field of communication antennas, and more particularly to a compact MIMO antenna system.

Background technique

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 at the same time, which can greatly improve the wireless transmission rate without increasing the transmission power or increasing the operating spectrum. It is the core technology of the fourth-generation mobile communication and fifth-generation communication systems. one. 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 distance between antennas, the signal interference between the antennas becomes larger, which seriously affects the performance of the MIMO system. The traditional method relies on increasing the distance between the antennas to achieve high isolation, and it is difficult to integrate more antenna devices into the wireless device, so it cannot meet the current demand for high transmission rate transmission.

Especially with the layout and promotion of the fifth-generation communication system, large-scale antenna arrays have become a trend, so the demand for compact MIMO antenna systems is getting higher and higher. In the prior art, the isolation between the antennas is mainly improved by introducing parasitic resonance, introducing a decoupling network, and using an orthogonal mode.

On the one hand, one of the most common ways to improve isolation is to introduce a new parasitic structure between the two antennas. The parasitic structure can generate an out-of-phase coupling route to cancel the original coupling between the antennas, thereby improving the antenna isolation. Spend. The type of parasitic structure can be slot, ring, strip, suspended structure, etc. However, this method needs to introduce an additional structure, which occupies a large space, which is not conducive to the miniaturized design of the antenna. In addition, this method is difficult to realize a highly compact MIMO antenna system.

On the other hand, the decoupling network usually adopts methods such as lumped element circuits or neutralizing lines to cancel the coupling between the antennas, which can effectively realize the design of compact MIMO antennas. However, this method requires more components or occupies a large circuit area, and is currently only suitable for monopole antennas or inverted-F antennas.

Furthermore, placing the 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, the antenna size required by this method is large, and it is difficult to realize the integration and miniaturization of the MIMO antenna system.

The above-mentioned prior art is only applicable to a certain type of antenna, and has no universality, and the above-mentioned prior art may not realize a compact MIMO system, or has a relatively complex decoupling structure, or has great application limitations , or with a larger antenna size.

Therefore, it is necessary to propose a simple and efficient decoupling technology to be compatible with different antenna types, to achieve a highly integrated, highly compact, and highly isolated MIMO antenna system, avoiding the time-consuming case analysis and analysis of traditional methods. Debugging, saving development cycle.

SUMMARY OF THE INVENTION

In order to solve the shortcomings of the prior art, the present invention provides a simple and effective decoupling technology, which is compatible with various antenna types, has the characteristics of compact antenna structure, small antenna unit size, close unit spacing, etc. Integrated, highly compact MIMO antenna system with high isolation. The invention can be applied to various wireless communication devices, and is especially suitable for the application of large-scale arrays in terminal devices.

The technical effect to be achieved by the present invention is achieved through the following scheme: a compact MIMO antenna system, comprising a ground plate, a first antenna, a second antenna and a ring decoupling structure, wherein the first antenna and the second antenna are radiators, It is used to generate antenna resonance and radiate, and the annular decoupling structure is used to decouple the first antenna and the second antenna; The side area produces strong current distribution and the current mode is opposite, and the middle area in the long side direction produces weak current distribution; the first antenna and the second antenna are arranged adjacently or electrically connected and formed in the middle of the ring decoupling structure in the long side direction area.

Preferably, the annular decoupling structure is a wire disposed outside the grounding plate, two ends of the annular decoupling structure are respectively connected to the grounding plate, and together with the grounding plate form a closed-loop structure.

Preferably, the annular decoupling structure is constituted by a first clearance area disposed inside the ground plate, and the first clearance area is an area removed from the ground plate.

Preferably, the first antenna and the second antenna are formed on the same side or different sides of the annular decoupling structure.

Preferably, both the first antenna and the second antenna are formed on the side of the ground plate and are electrically connected to the ground plate.

Preferably, it further includes a second clearance area and a third clearance area, the second clearance area and the third clearance area are areas removed from the ground plane, the first antenna is formed in the second clearance area, the The second antenna is formed in the third clearance area.

Preferably, the second clearance area and the third clearance area are formed on the same side or different sides of the annular decoupling structure.

Preferably, the second clearance area and the first clearance area are arranged in communication or not, and the third clearance area and the first clearance area are arranged in communication or not.

Preferably, components or branches are further connected in the weak current distribution area of the annular decoupling structure, and inductance elements are also connected in the strong current distribution area of the annular decoupling structure.

Preferably, the first antenna and the second antenna are ground radiation antennas, slot antennas, inverted-F antennas, monopole antennas, loop antennas or patch antennas.

The present invention has the following advantages:

1) Different from the existing technology, the ring decoupling structure in the present invention is a simple and efficient decoupling technology, which is compatible with different antenna types, and constitutes a compact MIMO antenna system with high isolation, which has a wider application prospects.

2) The present invention realizes a highly compact MIMO antenna system, and has the characteristics of compact structure, small unit size, and close unit spacing while realizing high isolation and low correlation.

Description of drawings

FIG. 1a shows a schematic diagram of the overall structure of Example 1 of the compact MIMO antenna system in the present invention;

Fig. 1b shows a schematic diagram of the overall structure of Example 2 of the compact MIMO antenna system in the present invention;

Fig. 1c shows a schematic diagram of the overall structure of Example 3 of the compact MIMO antenna system of the present invention;

Fig. 1d shows the current distribution diagram generated on the annular decoupling structure in the compact MIMO antenna system of the present invention;

2a and 2b are schematic structural diagrams in which the antenna of the compact MIMO antenna system is a ground radiation antenna in Embodiment 1 of the present invention;

3 is a schematic structural diagram in which the antenna of the compact MIMO antenna system in Embodiment 2 of the present invention is a slot antenna;

4a and 4b are schematic structural diagrams in which the antenna of the compact MIMO antenna system in Embodiment 3 of the present invention is an inverted-F antenna;

5 is a schematic structural diagram in which the antenna of the compact MIMO antenna system in Embodiment 4 of the present invention is a monopole antenna;

6 is a schematic structural diagram in which the antenna of the compact MIMO antenna system according to Embodiment 5 of the present invention is a loop antenna;

7a, 7b, and 7c are schematic structural diagrams in which the antenna of the compact MIMO antenna system in Embodiment 6 of the present invention is a ground radiation antenna;

8a, 8b, and 8c are schematic structural diagrams in which the antenna of the compact MIMO antenna system in Embodiment 7 of the present invention is a ground radiation antenna;

9a, 9b, 9c, 9d, and 9e are schematic diagrams showing other different embodiments of the annular decoupling structure of the compact MIMO antenna system in the present invention;

FIG. 10 shows an S-parameter diagram of a compact MIMO antenna system in a single-frequency mode according to the present invention;

FIG. 11 shows an S-parameter diagram of a compact MIMO antenna system in a dual-frequency mode according to the present invention.

Detailed ways

The present invention will be described in detail below with reference to the drawings and embodiments, examples of which are shown in the drawings, wherein the same or similar reference numerals represent the same or similar components or components with the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary, and are intended to explain the present invention and should not be construed as limiting the present invention.

In the description of the present invention, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", The orientation or positional relationship indicated by "horizontal", "top", "bottom", "inside", "outside", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, and It is not indicated or implied that the indicated device or component must have a particular orientation, be constructed and operate in a particular orientation, and therefore should not be construed as limiting the invention.

Furthermore, the terms "first", "second" and "third" are used for descriptive purposes only, and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, a feature defined as "first", "second", "third" may expressly or implicitly include one or more of that feature. In the description of the present invention, "plurality" means two or more, unless otherwise expressly and specifically defined.

In the present invention, unless otherwise expressly specified and limited, the terms "installed", "connected", "connected", "fixed" and "arranged" should be understood in a broad sense, for example, it may be a fixed connection or a It can be a detachable connection or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, or it can be the internal connection of two components or the interaction between the two components . For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

By deeply studying the coupling principle of MIMO antennas, the present invention proposes a decoupling method suitable for compact MIMO antenna systems. By combining a simple and efficient decoupling structure, the present invention can be compatible with various antenna types to form various types of compact MIMO antenna systems, and has wider application prospects.

FIG. 1 shows a schematic structural diagram of a compact MIMO antenna system in the present invention.

As shown in FIG. 1 a , a compact MIMO antenna system includes a ground plate 102 , a first antenna 110 a , a second antenna 110 b , and a ring-shaped decoupling structure 160 disposed outside the ground plate 102 . The ground plate 102 is laid on the printed circuit board.

According to an embodiment of the present invention, the first antenna 110a and the second antenna 110b are radiators, which generate antenna resonance and radiate. The first antenna 110a and the second antenna 110b are adjacently disposed on the same side of the ground plate 102, and the first antenna 110a and the second antenna 110b are closely spaced or electrically connected to form a compact MIMO antenna system. 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, in the present invention, a ring decoupling structure 160 is used to improve the isolation between the antennas and reduce the correlation between the antennas.

The annular decoupling structure 160 is a wire disposed outside the grounding plate 102, both ends are connected to the grounding plate 102, and together with the grounding plate 102 form a closed-loop structure, which is responsible for decoupling the first antenna 110a and the second antenna 110b, and improving the distance between the antennas. isolation between. The long side and the short side of the annular decoupling structure 160 are L and W respectively, the length of W is usually less than one tenth of a wavelength, and the current length of L is about half a wavelength, so the length of the long side is much longer than its short side. side length. Therefore, the annular decoupling structure 160 is an elongated closed-loop structure outside the ground plate 102 , and the distance between the first antenna 110 a and the second antenna 110 b is smaller than the length of the long side of the annular decoupling structure 160 . The annular decoupling structure 160 is connected to the ground plate 102 at the outer sides of the first antenna 110 a and the second antenna 110 b so that the first antenna 110 a and the second antenna 110 b are covered in the space between the annular decoupling structure 160 and the ground plate 102 . The first antenna 110a and the second antenna 110b are disposed adjacent to each other or electrically connected, and are disposed in the middle region (the middle position or the vicinity of the middle position) of the annular decoupling structure 160 in the longitudinal direction.

As shown in FIG. 1 b , a compact MIMO antenna system includes a ground plane 102 , a first antenna 110 a , a second antenna 110 b and a ring decoupling structure 160 disposed inside the ground plane 102 .

The annular decoupling structure 160 is formed by a first clearance area 106 disposed inside the grounding plate 102 . The first clearance area 106 is an area removed from the grounding plate and surrounded by the grounding plate 102 . The long side and the short side of the first clearance area 106 are W and L, respectively, and the length of the long side is greater than the length of the short side. Therefore, the annular decoupling structure 160 is an elongated closed-loop structure located inside the ground plate 102 . The first antenna 110a and the second antenna 110b are adjacently disposed on the same long side of the annular decoupling structure 160 , and are located in the middle region (the middle position or near the middle position) of the long side of the annular decoupling structure 160 . The first antenna 110a and the second antenna 110b are arranged adjacent to each other with a small distance, forming a compact MIMO antenna system.

As shown in FIG. 1 c , a compact MIMO antenna system includes a ground plate 102 , a first antenna 110 a , a second antenna 110 b , and a ring-shaped decoupling structure 160 disposed inside the ground plate 102 .

The annular decoupling structure 160 is formed by a first clearance area 106 disposed inside the grounding plate 102 . The first clearance area 106 is an area removed from the grounding plate and surrounded by the grounding plate 102 . The long side and the short side of the first clearance area 106 are W and L, respectively, and the length of the long side is greater than the length of the short side. Therefore, the annular decoupling structure 160 is an elongated closed-loop structure located inside the ground plate 102 . The first antenna 110 a and the second antenna 110 b are distributed on opposite long sides of the annular decoupling structure 160 , and both are located in the middle region (the middle position or near the middle position) of the long side of the annular decoupling structure 160 . The first antenna 110a and the second antenna 110b are arranged adjacent to each other with a small distance, forming a compact MIMO antenna system.

According to the embodiment of the present invention, the loop decoupling structure 160 can be applied to different types of antennas, such as ground radiation antennas, slot antennas, inverted-F antennas, monopole antennas, loop antennas, patch antennas or other commonly used antenna types Wait. The first antenna 110a and the second antenna 110b may be the same type of antenna, or may be different types of antennas. In addition, the first antenna 110a and the second antenna 110b may be single-frequency antennas or multi-frequency antennas. It should be understood by those skilled in the art that the first antenna, the second antenna, the annular decoupling structure and the ground plate may be arranged on the same plane, or may be arranged on different planes. All the drawings in the embodiments of the present invention are taken on the same plane as an example, which should not be taken as a limitation.

1d is a schematic diagram of the current distribution generated on the annular decoupling structure 160 in the present invention, so as to illustrate the working principle of the present invention.

As shown in FIG. 1d and in combination with FIG. 1a , by adjusting the connection position of the annular decoupling structure 160 and the ground plate 102 and the wire length of the annular decoupling structure 160 , a ring current distributed along the annular decoupling structure 160 will be generated. model. The annular current mode generates strong current distribution in the two sides of the annular decoupling structure 160 and the direction of the current mode is opposite. coupling area. The first antenna 110a and the second antenna 110b are located in the weak coupling area, so that the coupling paths between the antennas can be converted, and the isolation between the antennas can be greatly improved. By integrating the first antenna 110a and the second antenna 110b, a compact 2×2 MIMO antenna module with high isolation can be formed, thereby simplifying the transceiver circuit of the MIMO system.

Example 1

FIG. 2 shows a schematic structural diagram of a compact MIMO antenna system in Embodiment 1 of the present invention.

As shown in FIG. 2a and in conjunction with FIG. 1a, the antenna types of the first antenna 110a and the second antenna 110b are ground radiation antennas. A compact MIMO antenna system with high isolation includes: a ground plate 102, a first ground radiation antenna 210a arranged in the second clearance area 204a, a second ground radiation antenna 210b arranged in the third clearance area 204b, The annular decoupling structure 160 is disposed outside the ground plate 102 . The second clearance area 204a and the third clearance area 204b are the areas removed from the grounding plate, both are disposed on the side of the grounding plate 102, one side is open, and one side of the opening faces the outside of the grounding plate 102, and the other sides are open. Both sides are surrounded by ground planes.

As shown in FIG. 2b, the first ground radiation antenna 210a includes a first excitation structure 220a and a first resonance structure 240a.

The first excitation structure 220a includes a first feed 221a, a first wire 222a, a first component 223a and a second wire 224a, and is disposed inside the second clearance area 204a and surrounded by the first resonance structure 240a. One end of the first component 223a is connected to the first feeder 221a through a first wire 222a, the other end is connected to the ground plate 102 through a second wire 224a, and the first feeder 221a is connected to the ground plate 102. The first excitation structure 220a serves as an excitation circuit for the first ground radiation antenna 210a, which can control the matching of the antenna impedance and couple the RF signal in the first feed 221a to the first resonance structure 240a. The first component 223a may be a wire, an inductive element or a capacitive element.

The first resonance structure 240a includes a third wire 241a, a first capacitive element 242a and a fourth wire 243a, and is disposed on one side of the opening of the second clearance area 204a. One end of the first capacitive element 242a is connected to the ground plate 102 through a third wire 241a, and the other end is connected to the ground plate 102 through a fourth wire 243a. Therefore, the first resonant structure 240a can use the second clearance area 204a to form a ring-shaped resonator surrounding the clearance area, responsible for generating the resonance of the first ground radiating antenna 210a, and coupling the RF energy to the ground plate 102, using the ground plate 102 radiates as part of the antenna.

As shown in FIG. 2b, the second ground radiation antenna 210b has a symmetrical and same structure as the first ground radiation antenna 210a, including a second excitation structure 220b and a second resonance structure 240b.

The second excitation structure 220b includes a second feed 221b, a fifth wire 222b, a second component 223b and a sixth wire 224b, and is disposed inside the third clearance area 204b and surrounded by the second resonance structure 240b. One end of the second component 223b is connected to the second feed 221b through the fifth wire 222b, the other end is connected to the ground plate 202b through the sixth wire 224b, and the second feed 221b is connected to the ground plate 202b. The second excitation structure 220b serves as an excitation circuit for the second ground radiation antenna 210b, which can control the matching of the antenna impedance and couple the RF signal in the second feed 221b to the second resonance structure 240b. The components may be wires, inductive elements or capacitive elements.

The second resonance structure 240b includes a seventh wire 241b, a second capacitive element 242b and an eighth wire 243b, and is disposed on one side of the opening of the third clearance area 204b. One end of the second capacitive element 242b is connected to the ground plate 202 through the seventh wire 241b, and the other end is connected to the ground plate 102 through the eighth wire 243b. Therefore, the second resonant structure 240b can use the third clearance area 204b to form a ring-shaped resonator surrounding the clearance area, which is responsible for generating the resonance of the second ground radiating antenna 210b, and coupling the RF energy to the ground plate 102, using the ground plate 102 radiates as part of the antenna.

According to the embodiment of the present invention, the first ground radiating antenna 210a and the second ground radiating antenna 210b are disposed on the same side of the ground plate 102, and are arranged adjacent to each other with a small distance, forming a compact MIMO ground radiating antenna system .

The annular decoupling structure 160 is a wire disposed outside the grounding plate 102 , both ends are connected to the grounding plate 102 , and together with the grounding plate 102 form a closed-loop structure. The long side and the short side of the annular decoupling structure 160 are L and W respectively, and the length of the long side is greater than the length of the short side. The annular decoupling structure 160 is connected to the ground plate 102 at both outer sides of the first ground radiation antenna 210a and the second ground radiation antenna 210b. Therefore, the annular decoupling structure 160 is an elongated closed-loop structure outside the ground plate 102 . The first ground radiating antenna 210 a and the second ground radiating antenna 210 b are disposed in the middle region of the long side of the annular decoupling structure 160 and are surrounded by the annular decoupling structure 160 . This connection method can make full use of the coupling conversion effect of the annular decoupling structure 160 to generate a low coupling area between the first ground radiation antenna 210a and the second ground radiation antenna 210b, reduce the coupling between the antennas, and form a high isolation compact MIMO antenna system.

According to an embodiment of the present invention, the capacitive element has a capacitive component, and 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, and the like. In addition, the capacitive element may be composed of a single capacitive element, or may be composed of a plurality of capacitive elements connected to each other. In order to obtain a certain capacitance, the capacitive element can be replaced by a combination of multiple elements, for example, the capacitive element can be replaced by a combined structure of a capacitive element and an inductive element.

According to an embodiment of the present invention, the inductance element 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, and the like. Likewise, the inductive element may be formed by a single inductive element, or may be formed by connecting a plurality of inductive elements to each other.

Embodiment 2

FIG. 3 is a schematic structural diagram of a compact MIMO antenna system in Embodiment 2 of the present invention.

As shown in FIG. 3 and in conjunction with FIG. 1a, the antenna types of the first antenna 110a and the second antenna 110b are slot antennas. The compact MIMO antenna system includes the ground plate 102 , the first slot antenna 310 a , the second slot antenna 310 b , and the annular decoupling structure 160 disposed outside the ground plate 102 .

The first slot antenna 310a includes a third feed 320a, a first excitation line 321a, a third capacitive element 323a, and a first resonance line 322a. One end of the first resonant line 322a is connected to the ground plate 102, and the other end is electrically connected to the ground plate 102 through the third capacitive element 323a, and controls the resonance frequency of the first slot antenna 310a. The third capacitive element 323a can greatly shorten the wire length of the first resonance line 322a. One end of the first excitation line 321a is connected to the third feed 320a, the other end is connected to the first resonance line 322a, and the third feed 320a is connected to the ground plate 102 to control the impedance matching of the first slot antenna 310a.

The second slot antenna 310b is symmetrically arranged with the first slot antenna 310a and has the same structural features, including a fourth feed 320b, a second excitation line 321b, a fourth capacitive element 323b and a second resonance line 322b. One end of the second resonance line 322b is electrically connected to the ground plate 102, and one end is connected to the ground plate 102 through the fourth capacitive element 323b, and controls the resonance frequency of the second slot antenna 310b. The fourth capacitive element 323b can greatly shorten the wire length of the second resonance line 322b. One end of the second excitation line 321b is connected to the fourth feed 320b, the other end is connected to the second resonance line 340b, and the fourth feed 320b is connected to the ground plate 102 to control the impedance matching of the second slot antenna 310b.

According to the embodiment of the present invention, the first slot antenna 310a and the second slot antenna 310b are both disposed on the same side of the ground plate 102, adjacent to each other with a small distance between them, forming a compact MIMO antenna system. The annular decoupling structure 160 is a wire disposed outside the grounding plate 102 , both ends are connected to the grounding plate 102 , and together with the grounding plate 102 form a closed-loop structure. The long side and the short side of the annular decoupling structure 160 are L and W respectively, and the length of the long side is greater than the length of the short side. Therefore, the annular decoupling structure 160 is an elongated closed-loop structure outside the ground plate 102. The ring decoupling structure 160 is connected to the ground plate 102 at the outer sides of the first slot antenna 310a and the second slot antenna 310b. The first slot antenna 310a and the second slot antenna 310b are disposed in the middle area of the long side of the annular decoupling structure 160 and are surrounded by the annular decoupling structure 160 . This connection method can make full use of the coupling conversion effect of the annular decoupling structure 160 to generate a low coupling area between the antennas, reduce the coupling between the antennas, and achieve high isolation.

Embodiment 3

FIG. 4 is a schematic structural diagram of a compact MIMO antenna system in Embodiment 3 of the present invention.

As shown in FIG. 4a and in combination with FIG. 1a, the antenna types of the first antenna 110a and the second antenna 110b are inverted-F antennas. The compact MIMO antenna system includes the ground plate 102 , a first inverted-F antenna 410a , a second inverted-F antenna 410b , and a ring decoupling structure 160 disposed outside the ground plate 102 .

The first inverted-F antenna 410a includes a fifth feed 420a, a third excitation line 421a, and a third resonance line 422a. The third resonance line 422a has a frame shape, one end is connected to the ground plate 102, and the other end is open. The wire length of the third resonant line 422a is about a quarter wavelength, which determines the resonant frequency of the first inverted-F antenna 410a. One end of the third excitation line 421a is connected to the fifth feed 420a, and one end is connected to the third resonance line 422a. The fifth feed 420a is connected to the ground plate 102 to control the impedance matching of the first inverted-F antenna 410a.

The second inverted-F antenna 410b is disposed symmetrically with the first inverted-F antenna 410a, and has the same structural features, including a sixth feed 420b, a fourth excitation line 421b and a fourth resonance line 422b. The fourth resonance line 422b has a frame shape, one end is connected to the ground plate 102, and the other end is open. The wire length of the fourth resonant line 422b is about a quarter wavelength, which determines the resonant frequency of the second inverted-F antenna 410b. One end of the fourth excitation line 421b is connected to the sixth feed 420b, the other end is connected to the fourth resonance line 440b, and the sixth feed 420b is connected to the ground plate 102 to control the impedance matching of the second inverted-F antenna 410b.

According to an embodiment of the present invention, the first inverted-F antenna 410a and the second inverted-F antenna 410b are disposed on the same side of the ground plate 102, adjacent to each other, and the distance between them is small, forming a compact MIMO antenna system. The annular decoupling structure 160 is a wire disposed outside the grounding plate 102 , both ends are connected to the grounding plate 102 , and together with the grounding plate 102 form a closed-loop structure. The long side and the short side of the annular decoupling structure 160 are L and W respectively, and the length of the long side is greater than the length of the short side. Therefore, the annular decoupling structure 160 is an elongated closed-loop structure outside the ground plate 102. The loop decoupling structure 160 is connected to the ground plate 102 at the outer sides of the first inverted-F antenna 410a and the second inverted-F antenna 410b. The first inverted-F antenna 410a and the second inverted-F antenna 410b are disposed in the middle area of the long side of the annular decoupling structure 160 and are surrounded by the annular decoupling structure 160 . This connection method can make full use of the coupling conversion effect of the annular decoupling structure 160 to generate a low coupling area between the antennas, reduce the coupling between the antennas, and achieve high isolation.

FIG. 4b shows a modified structure of the second embodiment of the present invention.

As shown in FIG. 4b , the first inverted-F antenna 410a and the second inverted-F antenna 410b are directly connected and share part of the circuit structure, that is, the third resonant line 422a and the fourth resonant line 422b are connected and share part of the resonant line. The other circuit structures are the same as those in Figure 4a.

Embodiment 4

FIG. 5 is a schematic structural diagram of a compact MIMO antenna system in Embodiment 4 of the present invention.

As shown in FIG. 5 , in conjunction with FIG. 1 a , the antenna types of the first antenna 110 a and the second antenna 110 b are monopole antennas. The compact MIMO antenna system includes the ground plate 102 , a first monopole antenna 510 a , a second monopole antenna 510 b , and a ring decoupling structure 160 disposed outside the ground plate 102 .

The first monopole antenna 510a includes a seventh feed 520a and a fifth resonance line 521a. One end of the fifth resonance line 521a is connected to the seventh feeder 520a, the other end is open, and the seventh feeder 520a is connected to the ground plate 102. The wire length of the fifth resonance line 521a is about a quarter wavelength, which determines the resonance frequency of the first monopole antenna 510a.

The second monopole antenna 510b is disposed symmetrically with the first monopole antenna 510a, and has the same structural features, including an eighth feed 520b and a sixth resonance line 521b. One end of the sixth resonance line 521b is connected to the eighth feeder 520b, the other end is open, and the eighth feeder 520b is connected to the ground plate 102 . The wire length of the sixth resonant line 521b is about a quarter wavelength, which determines the resonant frequency of the second monopole antenna 510b.

According to the embodiment of the present invention, the first monopole antenna 510a and the second monopole antenna 510b are disposed on the same side of the ground plate 102, adjacent to each other, and the distance between them is small, forming a compact MIMO antenna. system. The annular decoupling structure 160 is a wire disposed outside the grounding plate 102 , both ends are connected to the grounding plate 102 , and together with the grounding plate 102 form a closed-loop structure. The long side and the short side of the annular decoupling structure 160 are L and W respectively, and the length of the long side is greater than the length of the short side. The ring decoupling structure 160 is connected to the ground plate 102 at the outer sides of the first monopole antenna 510a and the second monopole antenna 510b. Therefore, the annular decoupling structure 160 is an elongated closed-loop structure outside the ground plate 102 . The first monopole antenna 510 a and the second monopole antenna 510 b are disposed in the middle area of the long side of the annular decoupling structure 160 and are surrounded by the annular decoupling structure 160 . This connection method can make full use of the coupling conversion effect of the annular decoupling structure 160 to generate a low coupling area between the antennas, reduce the coupling between the antennas, and achieve high isolation.

Embodiment 5

FIG. 6 is a schematic structural diagram of a compact MIMO antenna system in Embodiment 5 of the present invention.

As shown in FIG. 6 , in conjunction with FIG. 1 a , the antenna types of the first antenna 110 a and the second antenna 110 b are loop antennas. The compact MIMO antenna system includes the ground plate 102 , a first loop antenna 610 a , a second loop antenna 610 b , and a loop decoupling structure 160 disposed outside the ground plate 102 .

The first loop antenna 610a includes a ninth feed 620a and a seventh resonance line 621a. One end of the seventh resonance line 621 a is connected to the ninth feeder 620 a , and the other end is connected to the ground plate 102 , and the ninth feeder 620 a is connected to the ground plate 102 . The wire length of the seventh resonant line 621a is about one-half wavelength, which determines the resonant frequency of the first loop antenna 610a. The first loop antenna 610a is characterized in that a weak current distribution is generated in the middle region of the seventh resonance line 621a, and a strong current distribution is generated near the ground point and the ninth feed 620a.

The second loop antenna 610b is disposed symmetrically with the first loop antenna 610a, and has the same structural features, including a tenth feed 620b and an eighth resonance line 621b. One end of the eighth resonance line 621b is connected to the tenth feeder 620b, the other end is connected to the ground plate 102, and the tenth feeder 620b is connected to the ground plate 102. The wire length of the eighth resonance line 621b is about one-half wavelength, which determines the resonance frequency of the second loop antenna 610b. The second loop antenna 610b is characterized in that a weak current distribution is generated in the middle region of the eighth resonance line 621b, and a strong current distribution is generated in the vicinity of the ground point and the tenth feed 620b.

According to an embodiment of the present invention, the first loop antenna 610a and the second loop antenna 610b are disposed on the same side of the ground plate 102, adjacent to each other, and the distance between them is small, forming a compact MIMO antenna system. The annular decoupling structure 160 is a wire disposed outside the grounding plate 102 , both ends are connected to the grounding plate 102 , and together with the grounding plate 102 form a ring-shaped decoupling body. The long side and the short side of the annular decoupling structure 160 are L and W respectively, and the length of the long side is greater than the length of the short side. The loop decoupling structure 160 is connected to the ground plate 102 at the outer sides of the first loop antenna 610a and the second loop antenna 610b. Therefore, the annular decoupling structure 160 is an elongated closed-loop structure outside the ground plate 102 . The first loop antenna 610a and the second loop antenna 610b are arranged in the middle area of the long side of the loop decoupling structure 160 and are surrounded by the loop decoupling structure 160 . This connection method can make full use of the coupling conversion effect of the annular decoupling structure 160 to generate a low coupling area between the antennas, reduce the coupling between the antennas, and achieve high isolation.

Embodiment 6

FIG. 7 is a schematic structural diagram of a compact MIMO antenna system in Embodiment 6 of the present invention.

As shown in FIG. 7a and in conjunction with FIG. 1b, a compact MIMO antenna system includes a ground plate 102, a first ground radiating antenna 710a disposed in the second clearance area 704a, and a second ground antenna disposed in the third clearance area 704b The radiating antenna 710b and the annular decoupling structure 160 disposed on the inner side of the ground plate 102 .

The annular decoupling structure 160 is formed by a first clearance area 106 disposed inside the grounding plate 102 . The first clearance area 106 is an area removed from the grounding plate and surrounded by the grounding plate 102 . The long side and the short side of the first clearance area 106 are W and L respectively, and the length of the long side is much larger than the length of the short side. Therefore, the annular decoupling structure 160 is an elongated closed-loop structure inside the ground plate 102 .

The first ground radiating antenna 710a is disposed in the second clearance area 704a, and the second clearance area 704a is the area removed from the ground plane, disposed inside the ground plane 102, and located on the long side of the annular decoupling structure 160 side. One side of the second clearance area 704a is open, one side of the opening faces the annular decoupling structure 160, and the other side is surrounded by the ground plate. The second ground radiating antenna 710b is disposed in the third clearance area 704b. The third clearance area 704b is an area removed from the grounding plate, and is disposed inside the grounding plate 102 and is arranged adjacent to the second clearance area 704a. It is disposed on the same long side of the first clearance area 106 together with the second clearance area 704a. One side of the third clearance area 704b is open, one side of the opening faces the annular decoupling structure 160, and the other side is surrounded by the ground plate. The circuit structures of the first ground radiation antenna 710a and the second ground radiation antenna 710b are the same as those in FIG. 2 .

According to the embodiment of the present invention, the first ground radiating antenna 710a and the second ground radiating antenna 710b are adjacently disposed on the same long side of the annular decoupling structure 160 and located in the middle area of the long side of the annular decoupling structure 160 . The first ground radiating antenna 710a and the second ground radiating antenna 710b are both disposed on the inner side of the ground plate 102 , and one side of the opening faces the annular decoupling structure 160 and is surrounded by the annular decoupling structure 160 . The distance between the first ground radiation antenna 710a and the second ground radiation antenna 710b is small, forming a compact MIMO ground radiation antenna. This connection method can make full use of the coupling conversion effect of the annular decoupling structure 160 to generate a low coupling area between the antennas, reduce the coupling between the antennas, and achieve high isolation.

FIG. 7b shows a modified structure of the sixth embodiment of the present invention.

As shown in FIG. 7b and in conjunction with FIG. 7a, the first ground radiating antenna 710a disposed in the second clearance area 704a and the second ground radiating antenna 710b disposed in the third clearance area 704b are adjacently disposed in the annular decoupling structure The long side of the same side of the ring-shaped decoupling structure 160 is located in the middle area of the long side of the annular decoupling structure 160 . The second clearance area 704 a is disposed on the side of the ground plate 102 , one side is open, and one side of the opening faces the outside of the ground plate 102 . The second clearance area 704a is disposed adjacent to the annular decoupling structure 160 with a small distance. The third clearance area 704 b is disposed on the inner side of the ground plate 102 , one side is open, and one side of the opening faces the annular decoupling structure 160 and is surrounded by the annular decoupling structure 160 . The other circuit structures are the same as in Fig. 7a. The first ground radiating antenna 710a and the second ground radiating antenna 710b are arranged adjacent to each other with a small distance, forming a compact MIMO ground radiating antenna. This connection method can make full use of the coupling conversion effect of the annular decoupling structure 160 to generate a low coupling area between the antennas, reduce the coupling between the antennas, and achieve high isolation.

FIG. 7c shows another modified structure of the sixth embodiment of the present invention.

As shown in FIG. 7c, and in conjunction with FIGS. 7a and 7b, the first ground radiating antenna 710a disposed in the second clearance area 704a and the second ground radiating antenna 710b disposed in the third clear area 704b are disposed adjacent to each other, and are disposed at The long sides of the annular decoupling structure 160 are on the same side and located in the middle region of the long sides of the annular decoupling structure 160 . Both the second clearance area 704 a and the third clearance area 704 b are disposed on the side of the ground plate 102 , one side is open, and one side of the opening faces the outside of the ground plate 102 . Both the second clearance area 704a and the third clearance area 704b are disposed adjacent to the annular decoupling structure 160 with a small distance. The other circuit structures are the same as in Fig. 7a. The first ground radiating antenna 710a and the second ground radiating antenna 710b are arranged adjacent to each other with a small distance, forming a compact MIMO ground radiating antenna. This connection method can make full use of the coupling conversion effect of the annular decoupling structure 160 to generate a low coupling area between the antennas, reduce the coupling between the antennas, and achieve high isolation.

Embodiment 7

FIG. 8 is a schematic diagram of a compact MIMO antenna system in Embodiment 7 of the present invention.

As shown in FIG. 8a and in conjunction with FIG. 1c, a compact MIMO antenna system includes a ground plate 102, a first ground radiating antenna 810a disposed in the second clearance area 804a, and a second ground antenna disposed in the third clearance area 804b The radiating antenna 810b and the annular decoupling structure 160 disposed inside the ground plate 102 .

The annular decoupling structure 160 is formed by a first clearance area 106 disposed inside the grounding plate 102 . The first clearance area 106 is an area removed from the grounding plate and surrounded by the grounding plate 102 . The long side and the short side of the first clearance area 106 are W and L respectively, and the length of the long side is much larger than the length of the short side. Therefore, the annular decoupling structure 160 is an elongated closed-loop structure inside the ground plate 102 .

The first ground radiating antenna 810a is disposed in the second clearance area 804a, and the second clearance area 804a is the area removed from the ground plane, which is disposed on the inner side of the ground plane 102 and is located on the long side of the ring decoupling structure 160. one side. One side of the second clearance area 804a is open, one side of the opening faces the annular decoupling structure 160, and the other side is surrounded by the ground plate. The second ground radiating antenna 810b is disposed in the third clearance area 804b. The third clearance area 804b is the area removed from the ground plane, and is disposed inside the ground plane 102 and disposed on the other side of the annular decoupling structure 160. The long side is opposite to the second clearance area 804a. One side of the third clearance area 804b is opened, one side of the opening faces the annular decoupling structure 160, and the other side is surrounded by the ground plate. The circuit structures of the first ground radiation antenna 810a and the second ground radiation antenna 810b are the same as those in FIG. 2 .

According to the embodiment of the present invention, the first ground radiation antenna 810a and the second ground radiation antenna 810b are respectively disposed on opposite long sides of the annular decoupling structure 160, and the first ground radiation antenna 810a and the second ground radiation antenna 810b Both are located in the middle area of the long side of the annular decoupling structure 160 , and both sides of the opening face the annular decoupling structure 160 . Thus, the first ground radiation antenna 810a and the second ground radiation antenna 810b constitute a compact MIMO ground radiation antenna. This connection method can make full use of the coupling conversion effect of the annular decoupling structure 160 to generate a low coupling area between the antennas, reduce the coupling between the antennas, and achieve high isolation.

FIG. 8b shows a modified structure of the seventh embodiment of the present invention.

As shown in FIG. 8b and in conjunction with FIG. 8a, the first ground radiating antenna 810a disposed in the second clearance area 804a and the second ground radiating antenna 810b disposed in the third clearance area 804b are respectively disposed on the annular decoupling structure 160 The long sides of the two opposite sides are located in the middle area of the long sides of the annular decoupling structure 160 . The second clearance area 804 a is disposed on the side of the ground plate 102 , one side is open, and one side of the opening faces the outside of the ground plate 102 . The second clearance area 804a is disposed adjacent to the annular decoupling structure 160 with a small distance. The third clearance area 804b is disposed on the inner side of the ground plate 102 , one side is open, and one side of the opening faces the annular decoupling structure 160 . The other circuit structures are the same as in Fig. 8a. The first ground radiation antenna 810a and the second ground radiation antenna 810b constitute a compact MIMO ground radiation antenna. This connection method can make full use of the coupling conversion effect of the ring decoupling structure 160, generate a low coupling area between the antennas, reduce the coupling between the antennas, and achieve high isolation.

FIG. 8c shows another modified structure of the seventh embodiment of the present invention.

As shown in FIG. 8c and in conjunction with FIG. 1c, the first ground radiating antenna 810a disposed in the second clearance area 804a and the second ground radiating antenna 810b disposed in the third clearance area 804b are respectively disposed on the annular decoupling structure 160 The long sides of the two opposite sides are located in the middle area of the long sides of the annular decoupling structure 160 . The second clearance area 804 a and the third clearance area 804 b are both disposed on the side of the grounding plate 102 , one side is open, and one side of the opening faces the outside of the grounding plate 102 . Both the second clearance area 804a and the third clearance area 804b are disposed adjacent to the annular decoupling structure 160 with a small distance. The other circuit structures are the same as in Fig. 8a. Thus, the first ground radiation antenna 810a and the second ground radiation antenna 810b constitute a compact MIMO ground radiation antenna. This connection method can make full use of the coupling conversion effect of the annular decoupling structure 160 to generate a low coupling area between the antennas, reduce the coupling between the antennas, and achieve high isolation.

As can be seen from the above, the first antenna and the second antenna in the compact MIMO antenna system may be ground radiation antennas, slot antennas, inverted-F antennas, monopole antennas, loop antennas, patch antennas or other types of antennas. In addition, according to specific design requirements, the structure, type, connection method and setting method of the antenna can constitute different implementation cases. For example, the first antenna and the second antenna can adopt various technical methods such as excitation circuits and loading elements to Realize different performance indicators such as miniaturization, broadband, multi-band, polarization, etc. In the present invention, there is no specific limitation on the structure, type, connection mode, setting mode, etc. of the first antenna and the second antenna. Therefore, the decoupling technology of the present invention is applicable to a variety of antenna types, thereby forming a compact MIMO antenna system, which is the first time in the prior art and has wider application scenarios.

FIG. 9 shows a schematic diagram of different embodiments of the annular decoupling structure of the present invention.

As shown in FIGS. 9 a to 9 c , and in conjunction with FIG. 1 d , in the weak current region of the annular decoupling structure 160, a component 901 can be connected, or a branch 902 can be connected, and the branch 902 includes a fifth capacitive element 903; In the high current region of the decoupling structure 160, the inductance element 904 can be connected in series. The method can control the operating frequency of the annular decoupling structure 160, greatly reduce the length of the long side of the annular decoupling structure, and realize the miniaturization of the annular decoupling structure. As shown in FIGS. 9d and 9e, the branch 905 or the branch 906 including the component 907 can be connected in the ring decoupling structure 160 to form one or more ring current modes, so that one or more working modes can be generated, in one or more It plays the role of coupling conversion in one frequency band, that is, it improves the isolation of the antenna in one or more frequency bands.

FIG. 10 shows an S-parameter diagram of a compact MIMO antenna system in a single frequency mode according to the present invention.

As shown in FIG. 10, the first curve 10a is the reflection coefficient generated by the first antenna 110a, and the second curve 10b is the reflection coefficient generated by the second antenna 110b. The center frequency of both antennas is around 3.5GHz, which has broadband characteristics. The third curve 10c is the reverse transmission coefficient between the two antennas, which represents the coupling degree between the antennas. It can be known that the third curve 10c generates a coupling peak and valley in the working frequency band, so as to ensure the coupling between the antennas. Produce higher isolation (above 20dB). In addition, the radiation efficiency of the compact MIMO antenna system is above 80%, and the correlation degree (ECC) obtained in both simulation and test is lower than 0.1. Therefore, the compact MIMO antenna system in the present invention has the characteristics of high isolation, good radiation performance, low correlation, etc., and is suitable for the application of the MIMO system.

FIG. 11 shows an S-parameter diagram of a compact MIMO antenna system in a dual-frequency mode according to the present invention.

9 , it can be seen that the compact MIMO antenna system in the present invention can generate one or more resonances, and realize the decoupling effect in a single frequency band or multiple frequency bands through one or more annular decoupling structures. As shown in FIG. 11, the first curve 11a and the second curve 11b are the reflection coefficients generated by the first antenna 110a and the second antenna 110b, respectively. The two antennas resonate in the 3.5GHz and 5.5GHz frequency bands at the same time. The third curve 11c is the reverse transmission coefficient between the antennas, which represents the coupling degree between the antennas. It can be known that the isolation degree in the two frequency bands is above 10 dB. Therefore, the decoupling technique in the present invention is also applicable to the compact MIMO antenna system in the multi-band mode.

To sum up, the above-mentioned embodiment has the following characteristics compared with the prior art:

1) The down-coupling technology in the present invention can be applied to various types of antennas, and can be used as a general down-coupling technology to realize a compact MIMO antenna system with high isolation. With the characteristics of close spacing, high isolation and low correlation, it has a wider application scene.

2) The compact MIMO antenna system in the present invention is not only applicable to a single frequency band, but also to multiple frequency bands.

The above descriptions are the preferred embodiments of the present invention, and do not limit the present invention in any form. Several improvements and modifications are also within the scope of the present invention.

Claims (10)

1. A compact MIMO antenna system is characterized by comprising a grounding plate, a first antenna, a second antenna and an annular decoupling reduction structure, wherein the first antenna and the second antenna are radiators and are used for generating antenna resonance and radiating, and the annular decoupling reduction structure is used for decoupling the first antenna and the second antenna; the annular decoupling structure is a long and narrow closed-loop structure connected to the grounding plate, strong current distribution is generated in two side areas in the long edge direction, the current modes are opposite, and weak current distribution is generated in the middle area in the long edge direction; the first antenna and the second antenna are arranged adjacently or electrically connected and formed in the middle area in the long side direction of the annular decoupling structure.

2. The compact MIMO antenna system of claim 1, wherein the ring decoupling structure is a conductive wire disposed outside the ground plate, and both ends of the ring decoupling structure are respectively connected to the ground plate to form a closed loop structure together with the ground plate.

3. The compact MIMO antenna system of claim 1, wherein the ring decoupling structure is formed by a first clearance area disposed inside the ground plane, the first clearance area being a removed area of the ground plane.

4. A compact MIMO antenna system according to claim 2 or 3 wherein the first and second antennas are formed on the same or different sides of a circular decoupling structure.

5. The compact MIMO antenna system of claim 2, wherein the first antenna and the second antenna are each formed on a side of the ground plane and are each electrically connected to the ground plane.

6. The compact MIMO antenna system of claim 2 or 3, further comprising a second clearance area and a third clearance area, the second clearance area and the third clearance area being areas where the ground plane is removed, the first antenna being formed in the second clearance area, the second antenna being formed in the third clearance area.

7. The compact MIMO antenna system of claim 6, wherein the second and third clearance areas are formed on the same side or different sides of a ring-type decoupling structure.

8. The compact MIMO antenna system of claim 7, wherein the second headroom region is in communication with or not in communication with the first headroom region, and wherein the third headroom region is in communication with or not in communication with the first headroom region.

9. The compact MIMO antenna system of claim 1, wherein the circular decoupling-down structure further has components or branches connected to the weak current distribution area, and the circular decoupling-down structure further has inductive elements connected to the strong current distribution area.

10. The compact MIMO antenna system of any one of claims 1-9, wherein the first antenna and the second antenna are ground radiating antennas, slot antennas, inverted-F antennas, monopole antennas, loop antennas, or patch antennas.

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