CN115020993A

CN115020993A - MIMO antenna

Info

Publication number: CN115020993A
Application number: CN202210684255.9A
Authority: CN
Inventors: 马磊
Original assignee: Kunshan Ruixiang Xuntong Communication Technology Co Ltd
Current assignee: Kunshan Ruixiang Xuntong Communication Technology Co Ltd
Priority date: 2022-06-16
Filing date: 2022-06-16
Publication date: 2022-09-06

Abstract

The invention provides an MIMO antenna which is characterized by comprising a floor, a metal frame, a radiation structure, a feed structure, a connection structure and a grounding structure, wherein the metal frame is arranged on the floor; the metal frame is perpendicular to the floor; the radiation structure is a slot structure close to and parallel to the upper long edge of the metal frame; a first gap, a second gap and a third gap are sequentially arranged at the position, close to the radiation structure, of the upper long side of the metal frame; the first gap, the second gap and the third gap are connected with the radiation structure, so that the bandwidth of the radiation structure is expanded; the grounding structure is added, the good isolation of the MIMI antenna can be realized by the grounding structure, so that a high-isolation broadband multi-MIMO antenna system is realized, the size of the MIMO antenna system is reduced, and a good radiation effect is realized.

Description

MIMO antenna

Technical Field

The invention relates to the field of wireless communication, in particular to a design of a terminal multi-MIMO antenna.

Background

MIMO antenna: MIMO is very simple to define, and any wireless communication system can be called MIMO wireless communication system when its receiving end and transmitting end use multiple antennas for data transmission. MIMO systems typically use distributed antennas with large antenna element spacing, and the signals on the antennas can be considered independent. The MIMO technology effectively utilizes random fading and multipath propagation to improve transmission rate and quality, and its advantages can be fully embodied in an environment rich in scatterers.

More than two antennas are used at both the transmitting end and the receiving end of the wireless communication system, so that the wireless communication system can become a multiple-input multiple-output (MIMO) system, and the MIMO system can fully utilize the diversity technology of transmitting and receiving, thereby increasing the diversity gain of the antennas. Under certain conditions, each transmitting signal of a transmitting end transmits a plurality of signals in the same frequency band by using different antennas, a receiving end also receives incoming wave signals by using a plurality of antennas and corresponding processing technologies, and the signals are transmitted in the same time and frequency band, so that the frequency spectrum utilization rate is particularly high, and the signal capacity is linearly increased along with the increase of the number of the antennas.

An antenna pair: in terminal antenna MIMO design, a case where two or more antennas share a radiator or branch to be connected may be referred to as an antenna pair, and in general, it is common to design an antenna composed of two antennas; the core idea of the antenna pair is to reduce the whole volume of the whole antenna system by sharing a radiator or arranging antennas at a short distance. The more antennas are contained in the antenna pair, the more the volume can be reduced, but the corresponding problem that S parameters are deteriorated and difficult to adjust due to mutual influence of multiple antennas also exists.

The 5G sub-6GHz band has 3.4-3.6GHz and 4.8-5.0GHz, so a wide bandwidth antenna needs to be designed to cover these bands, and in a conventional scheme, different antennas cover different bands, but in consideration of the fact that a terminal antenna also needs to be designed with a MIMO antenna, the number of antennas is multiplied, so a broadband antenna scheme needs to be provided to cover the sub-6GHz band and ensure a smaller antenna size.

The terminal generally needs to design 4MIMO antennas to cover a 5G sub-6GHz band, and the 4MIMO antennas generally need to be distributed on two long sides of the terminal, so that too much space is occupied, and the space reserved for 2/3/4G is extremely limited, which is a great challenge in the large trend of large-screen mobile phones and metal-shell mobile phones.

Disclosure of Invention

The invention aims to provide a MIMO antenna, which solves the problems of large size, large occupied space and high cost of an antenna system caused by more antennas required by the requirement of sub-6GHz multi-band at present.

In order to solve the above problems, the present invention provides an MIMO antenna, which includes a floor, a metal frame with a rectangular structure, and an antenna assembly;

the metal frame is perpendicular to the floor; a first gap, a second gap and a third gap are sequentially arranged on the long edge of the metal frame;

the antenna assembly comprises a radiation structure, a feed structure, a grounding structure and a connection structure; the radiation structure is connected with the first gap, the second gap and the third gap; the feed structure is connected between the floor and the metal frame; the feed structure comprises a first feed point, a second feed point, a third feed point and a fourth feed point; the grounding structure is connected with the floor and the long edge of the metal frame; the connecting structure is connected with the upper long-edge part of the metal frame and the floor at two sides of the second gap.

Optionally, in the MIMO antenna, the length of the floor is 120 ± 12mm, the width of the floor is 70 ± 7mm, and the back surface of the floor is covered with copper.

Optionally, in the MIMO antenna, the height of the metal frame is 7 ± 0.7 mm.

Optionally, in the MIMO antenna, the radiation structure is a slot structure, and is connected to the first slot, the second slot, and the third slot to form an open slot radiation structure.

Optionally, in the MIMO antenna, the length of the radiating structure is 54 ± 5.4mm, and the width is 4 ± 0.4 mm.

Optionally, in the MIMO antenna, the widths of the first slot and the third slot are equal to each other and are 3 ± 0.3 mm.

Optionally, in the MIMO antenna, the second slot is located at a middle position between the first slot and the third slot, and a width of the second slot is 2 ± 0.5 mm.

Optionally, in the MIMO antenna, the connection structure is a strip structure parallel to a long side of the metal frame.

Optionally, in the MIMO antenna, the width of the grounding structure is 3 ± 0.3mm, an inductor is connected in series between the strips, and the inductance value connected in series between the grounding structures is 18-33 nh.

Optionally, in the MIMO antenna, the first feeding point and the second feeding point are located at two sides of the first slot, and a distance between the first feeding point and the first slot is 13 ± 1 mm; the third feeding point and the fourth feeding point are located on two sides of the third gap, and the distance between the fourth feeding point and the third gap is 13 +/-1 mm.

The invention has the beneficial effects that:

the invention adopts the scheme of sharing the slot radiator to realize the miniaturized design of the size of the antenna, an open slot radiation structure is arranged near the metal frame to form a multi-mode open loop slot structure, and the bandwidth of the antenna is widened by adding a slot connected with the radiation structure on the metal frame to form complete long slot radiation; the isolation between the MIMO antennas is improved by adding a connecting structure for connecting the metal frame and a connecting structure for connecting the floor and the metal frame; therefore, the high-isolation broadband multi-MIMO antenna system is realized, the size of the MIMO antenna system is reduced, and a good radiation effect is realized.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a structural diagram of a MIMO antenna provided in this embodiment;

fig. 2 is a simulation diagram of S parameters of a MIMO antenna according to the present embodiment;

fig. 3 is a comparison diagram of the isolation before and after the connection structure of the MIMO antenna is added;

fig. 4 is a simulation diagram of surface current distribution of a MIMO antenna provided in this embodiment;

fig. 5 is a simulation diagram of a radiation direction of a MIMO antenna according to the present embodiment;

fig. 6 is a simulation diagram of the efficiency of a MIMO antenna provided in this embodiment;

wherein the reference numerals are as follows:

1-floor board; 2-a metal frame; 3-a radiating structure; 4-a linking structure; 5-a ground structure; 6-a feed structure; 21-a first slit; 22-a second gap; 23-a third gap; 61-first feeding point; 62-a second feeding point; 63-a third feeding point; 64-fourth feeding point.

Detailed Description

The following describes a MIMO antenna and a terminal according to the present invention in further detail with reference to the accompanying drawings and specific embodiments. It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the accompanying drawings are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order, and it is to be understood that such structures as are used are interchangeable where appropriate. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

The invention provides a miniaturized multi-MIMO antenna, wherein an open type gap radiation structure is arranged near a metal frame, and a gap connected with the radiation structure is added on the metal frame to form complete long gap radiation, so that the bandwidth of the antenna is widened; the isolation between the MIMO antennas is improved by adding a connecting structure for connecting the metal frame and a connecting structure for connecting the floor and the metal frame; therefore, the high-isolation broadband multi-MIMO antenna system is realized, the size of the MIMO antenna system is reduced, and a good radiation effect is realized.

The following describes the multi-MIMO antenna provided by the present invention with reference to specific embodiments:

fig. 1 is a structural diagram of an MIMO antenna provided in this embodiment, and as shown in fig. 1, the MIMO antenna provided in the present invention includes a floor 1, a metal frame 2 and an antenna assembly; the antenna assembly comprises a radiating structure 3, a connecting structure 4, a ground structure 5 and a feed structure 6; the metal frame 2 is arranged perpendicular to the floor 1.

More preferably, the length of the floor 1 is 120 plus or minus 12mm, the width is 70 plus or minus 7mm, and the back surface is covered with copper; the thickness of the metal frame 2 is 1.54 mm plus or minus 0.1mm, and the height of the metal frame 2 is 7mm plus or minus 0.7 mm.

The radiation structure 3 is a slot structure parallel to the long edge of the metal frame 2, and forms a shared MIMO antenna radiator; the first gap 21, the second gap 22 and the third gap 23 are sequentially arranged at the position, close to the radiation structure 3, of the upper long side of the metal frame 2; the first slot 21, the second slot 22 and the third slot 23 are connected to the radiation structure 3, so as to further form an open-type common slot radiator structure, and on the premise of not occupying more space, a plurality of MIMO antennas can be formed, thereby covering more frequency ranges; the second slit 22 is connected to an intermediate position of the radiation structure 3.

More preferably, the length of the radiation structure 3 is 54 ± 5.4mm, and the width is 4 ± 0.4 mm; the widths of the first gap 21 and the third gap 23 are equal and are 3 +/-0.3 mm; the width of the second gap is 2 +/-0.5 mm; the radiation structure 3, the first gap 21, and the third gap 23 are used as a common open radiation structure, so the size can be adjusted according to different terminal sizes, and the specific adjustment manner is well known to those skilled in the art and is not described herein again; the second slot 22 is used for improving the isolation between multiple MIMO antennas, the wider the slot, the better the isolation between MIMO antennas, but the preferred size is 1.5-2.5 mm because of the robust characteristic and continuity of the whole structure.

The connection structure 4 in the shape of "Jiong" is located above the metal frame 2 and connects the upper long edge portions of the metal frame 2 located on both sides of the first slot 21 and the third slot 23, and the arrangement of the grounding structure can improve the isolation between the MIMO antennas; the grounding structure 5 connects the long part of the metal frame 2 on both sides of the second gap 22 with the floor board 1, and the grounding structure 5 divides the large gap on the whole floor board 1 into two parts, so as to reduce the mutual influence among the first feeding point, the second feeding point, the third feeding point and the fourth feeding point.

More preferably, the width of the connecting structure 4 is 2 ± 0.2 mm; the width of the grounding structure 5 is 3 +/-0.3 mm, an inductor is connected in series between the strips, and the inductance value of the grounding structure 5 connected in series is 18-33 nh; the effect of increasing the inductance is that the slot antenna presents the capacitance, so the series inductance is increased to neutralize the capacitance characteristic, thereby better playing the role of isolating the current mode between the slots.

Fig. 2 is a simulation diagram of S parameters of a MIMO antenna provided in this embodiment, in which S11, S22, S33, and S44 are shown by solid lines, and it can be seen that-6 dB bandwidth is approximately 3-7 GHz; the isolation parameter is indicated by a dotted line, and it can be seen from the figure that the isolation is greater than 10dB in most frequency bands in the band, which indicates that the isolation of the MIMO antenna is good.

Further, fig. 3 is a comparison diagram of the isolation before and after the connection structure is added to the MIMO antenna provided by this embodiment, and it can be seen from the diagram that the isolation before the S12 optimization is only 4dB, and reaches more than 10dB after the S12 optimization, and is also only 5dB before the S32 optimization, and reaches 15dB after the S32 optimization, therefore, after the connection structure 4 and the ground structure 5 are added, the isolation is greatly improved, so that when a large slot is used to realize the design of a 4MIMO antenna, a better isolation between antennas is also realized.

The feeding structure 6 comprises the first feeding point 61, the second feeding point 62, the third feeding point 63 and the fourth feeding point 64; the first feeding point and the second feeding point are positioned on two sides of the first gap, and the preferable distance between the first feeding point and the first gap is 13 +/-1 mm; the third feeding point and the fourth feeding point are positioned on two sides of the third gap, and the preferred distance between the fourth feeding point and the third gap is 13 +/-1 mm; specifically, the first feeding point 61 connects the long-side portion of the metal frame 2 on the left side of the first slot 21 (the side close to the radiating structure is the left side) with the floor 1; the second feeding point 62 connects the upper long portion of the metal frame 2 between the first slot 21 and the second slot 22 with the floor panel 1; the third feeding point 63 connects the upper long portion of the metal frame 2 between the second gap 22 and the third gap 23 with the floor panel 1; the fourth feeding point 64 is connected to the upper long portion of the metal frame 2 on the right side of the third gap 23 and the floor panel 1; the four feeding points are fed respectively to form a 4MIMO antenna, so that a higher broadband can be realized without occupying additional internal space of the terminal.

Fig. 4 is a surface current distribution simulation diagram of the MIMO antenna provided in this embodiment, and it is seen from the diagram that the currents at four frequency points of 3.5GHz, 4.5GHz, 5.5GHz, and 6.5GHz are concentrated at different positions of the slot, and the positions of the extreme point of the current distribution along the edge of the metal structure are also different, which indicates that the complete slot realizes broadband radiation of 3 to 7 GHz.

Fig. 5 is a simulation diagram of the radiation direction of the MIMO antenna provided in this embodiment, and it can be seen from the diagram that the gains of most frequency points are greater than 3dBi, so that the 4MIMO antenna realizes good radiation.

Fig. 6 is a simulation diagram of the efficiency of the MIMO antenna provided in this embodiment, and it can be seen from the diagram that the in-band efficiency is above 30%, and the individual frequency points reach 50%, which is acceptable efficiency for the MIMO antenna of the terminal, and the efficiency is slightly reduced compared to that of a single antenna, mainly due to mutual interference between antennas, and the total efficiency of 40% can satisfy the design of the terminal antenna.

In summary, the present embodiment provides a MIMO antenna, which includes a floor, a metal frame with a rectangular structure, and an antenna assembly; the metal frame is perpendicular to the floor; a first gap, a second gap and a third gap are sequentially arranged on the long edge of the metal frame; the antenna assembly comprises a radiation structure, a feed structure, a grounding structure and a connection structure; the radiation structure is connected with the first gap, the second gap and the third gap; the feed structure is connected between the floor and the metal frame; the feed structure comprises a first feed point, a second feed point, a third feed point and a fourth feed point; the grounding structure is connected with the floor and the long edge of the metal frame; the connecting structure is connected with the upper long part of the metal frame and the floor at two sides of the second gap; the first gap, the second gap and the third gap are connected with the radiation structure, so that the bandwidth of the radiation structure is expanded; the grounding structure is positioned above the metal frame and is connected with the upper long edge part of the metal frame on two sides of the first gap and the third gap; the grounding structure is connected with the upper long part of the metal frame and the floor at two sides of the second gap, and the addition of the connecting structure improves the isolation of the MIMO antenna; the multi-MIMI broadband antenna system is realized under the condition of not occupying too much space, and the problems that the antenna system is large in size, large in occupied space and high in cost due to the fact that the number of antennas required for the requirement of sub-6GHz multi-band at present is large are solved.

The above description is only for the purpose of describing the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art based on the above disclosure are intended to fall within the scope of the appended claims.

Claims

1. The MIMO antenna is characterized by comprising a floor, a metal frame with a rectangular structure and an antenna assembly;

2. A MIMO antenna according to claim 1, wherein the floor has a length of 120 ± 12mm and a width of 70 ± 7mm, and is coated with copper on the back side.

3. The MIMO antenna of claim 1, wherein the metal bezel has a height of 7 ± 0.7 mm.

4. The MIMO antenna of claim 1, wherein the radiating structure is a slot structure and is connected to the first slot, the second slot, and the third slot to form an open slot radiating structure.

5. A MIMO antenna according to claim 1, wherein the radiating structure has a length of 54 ± 5.4mm and a width of 4 ± 0.4 mm.

6. A MIMO antenna according to claim 1, wherein the width of the first slot and the third slot are equal and are 3 ± 0.3 mm.

7. A MIMO antenna according to claim 1, wherein the second slot is located at an intermediate position between the first slot and the third slot, and the width of the second slot is 2 ± 0.5 mm.

8. The MIMO antenna according to claim 1, wherein the width of the grounding structure is 3 ± 0.3mm, an inductor is connected in series between the strips, and the inductance value of the grounding structure in series between the strips is 18-33 nh.

9. A MIMO antenna according to claim 1, wherein the connection structure is a strip structure parallel to the long side of the metal frame.

10. A MIMO antenna according to claim 1, wherein the first feeding point and the second feeding point are located on both sides of the first slot, and the distance between the first feeding point and the first slot is 13 ± 1 mm; the third feeding point and the fourth feeding point are located on two sides of the third gap, and the distance between the fourth feeding point and the third gap is 13 +/-1 mm.