CN109659686B

CN109659686B - High-isolation MIMO antenna

Info

Publication number: CN109659686B
Application number: CN201910055614.2A
Authority: CN
Inventors: 刘飞; 吉祥生
Original assignee: Huizhou Speed Wireless Technology Co Ltd
Current assignee: Huizhou Speed Wireless Technology Co Ltd
Priority date: 2019-01-22
Filing date: 2019-01-22
Publication date: 2023-10-20
Anticipated expiration: 2039-01-22
Also published as: CN109659686A

Abstract

The invention discloses a high-isolation MIMO antenna, which comprises a dielectric substrate (1), at least two antenna radiation ends (2), a filtering decoupling network (3) and a grounding plate, wherein the antenna radiation ends (2) and the filtering decoupling network (3) are arranged on one surface of the dielectric substrate (1), and the grounding plate is arranged on the other surface of the dielectric substrate (1); the filtering decoupling network (3) is connected between the antenna radiation ends (2). The antenna is used for the intelligent terminal.

Description

High-isolation MIMO antenna

Technical Field

The invention relates to the technical field of antennas, in particular to a high-isolation MIMO antenna.

Background

Mobile communication is one of the most rapid fields developed at present, and has undergone several generations of transformation, so that unprecedented high efficiency and convenience are provided for people from mobile phones and the internet, particularly in the field of mobile communication, the emergence of electromagnetic waves realizes the leap development from wired communication to wireless communication, and the current multimedia communication realizes the comprehensive business data transmission from single voice data to integrated images, data, audio and the like. In recent years, with more and more end users and wireless data communication services, the communication system provides wider frequency band bandwidth and higher rate data communication services to the demands of wireless, high-speed and diversified, so that the wireless communication system plays an increasingly important role in people's life.

In the 4G and 5G communications era, intelligent terminals have become a major tool for people to access the internet, which requires that the intelligent terminals can realize high reliability and high rate data transmission. The mimo technology is a key technology for solving the problem, and is widely used in the base station side and the mobile terminal of the 4G communication. The MIMO system is characterized in that a transmitter or a receiver is provided with a plurality of antennas, and the transmission quality and the system capacity can be improved by utilizing the multipath attribute of a wireless channel on the premise of not increasing the transmission power and the system frequency spectrum. For a MIMO system to have good performance, the antenna elements must be uncorrelated (coupling low), however, the space that can be reserved for antennas in a mobile device is very limited, so that the spatial distance between antennas cannot be greater than or equal to one wavelength. Integrating multiple broadband antennas with low coupling in portable devices is then a relatively tricky problem, especially in reducing the coupling between multiple antennas in a confined space.

Disclosure of Invention

The invention solves the technical problem of providing a MIMO antenna with lower coupling aiming at the defects in the background technology.

In order to solve the technical problems, the technical scheme of the invention is as follows: the high-isolation MIMO antenna comprises a dielectric substrate, at least two antenna radiation ends, a filtering decoupling network and a grounding plate, wherein the antenna radiation ends and the filtering decoupling network are arranged on one surface of the dielectric substrate, and the grounding plate is arranged on the other surface of the dielectric substrate; the filtering decoupling network is connected between the radiation ends of each antenna.

Further, the filtering decoupling network comprises first extension branches and a semi-closed structure, each antenna radiation end extends to a position between each antenna radiation end to form a first extension branch, each first extension branch extends into the semi-closed structure from an opening of the semi-closed structure, and a plurality of second extension branches are arranged in the semi-closed structure.

Further, the antenna radiation end is a monopole radiation patch printed on the dielectric substrate.

Further, the antenna radiation end is an F-shaped metal patch.

Further, the grounding plate is a metal patch printed on the dielectric substrate.

Further, the dielectric substrate is an FR4 substrate with a dielectric constant of 4.4+/-3%.

Further, a 50 ohm feed microstrip line is connected at a feed point of the antenna radiation end.

Further, the antenna comprises two symmetrically arranged antenna radiation ends, and the filtering decoupling network is arranged between the two antenna radiation ends.

The beneficial effects achieved by the invention mainly comprise the following points: the filtering decoupling network is arranged between the antenna radiation ends, and the wave radiated by one antenna is reduced to be absorbed by other antennas by filtering the wave between the antennas, so that the mutual coupling between the antenna radiation ends is reduced, and the isolation degree of the antenna radiation ends is improved.

Drawings

Fig. 1 is a schematic structural diagram of a front surface of a high isolation MIMO antenna according to an embodiment of the present invention;

fig. 2 is a schematic diagram of a frequency-dependent variation curve of S parameters of a high-isolation MIMO antenna according to an embodiment of the present invention.

The drawings are for illustrative purposes only and are not to be construed as limiting the present patent; for the purpose of better illustrating the embodiments, certain elements of the drawings may be omitted, enlarged or reduced and do not represent the actual product dimensions; it will be appreciated by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted; the same or similar reference numerals correspond to the same or similar components; the terms describing the positional relationship in the drawings are merely illustrative and should not be construed as limiting the present patent.

Detailed Description

The present invention will be described in further detail below with reference to the drawings and examples for the understanding of those skilled in the art.

Example 1

Referring to fig. 1, a high isolation MIMO antenna may be used as an antenna for intelligent mobile terminals such as mobile phones. The MIMO antenna comprises a dielectric substrate 1, at least two antenna radiation ends 2, a filtering decoupling network 3 and a grounding plate (not shown in the figure), wherein the antenna radiation ends 2 and the filtering decoupling network 3 are arranged on one surface of the dielectric substrate 1 and can be arranged on the front surface of the dielectric substrate 1; the ground plate is disposed on the other surface of the dielectric substrate 1, and may be disposed on the back surface of the dielectric substrate 1. The multiple antenna radiation ends 2 form a MIMO antenna, the filtering decoupling network 3 is connected between the antenna radiation ends 2, and the wave radiated by one antenna is reduced to be absorbed by other antennas by filtering the wave between the antennas, so that the mutual coupling between the antenna radiation ends 2 is reduced, and the isolation degree of the antenna radiation ends is improved. The filtering decoupling network 3 can adopt the existing filtering circuits such as LC and RC circuits, and preferably sets a plurality of groups of LC and RC filtering circuits to realize multi-band filtering between the radiating ends of the antennas, so that the mutual coupling of each frequency band can be reduced when the MIMO antenna of the embodiment radiates and receives under a broadband, and the isolation of the antenna under the broadband operation is ensured.

Referring to fig. 1 and 2, the filtering decoupling network 3 preferably adopts the following structure: the antenna comprises a first extending branch 31 and a semi-closed structure 32, wherein each antenna radiation end 2 extends to a position between each antenna radiation end to form a first extending branch 31, each first extending branch 31 extends into the semi-closed structure 32 from an opening of the semi-closed structure 32 (is not contacted with the semi-closed structure 32), and electric waves radiated to other antenna radiation ends 2 by each antenna radiation end 2 are introduced into a filtering decoupling network 3 through the first extending branch 31, so that the electric waves radiated to other antennas by the antenna are reduced, the coupling between the antenna radiation ends 2 is reduced, and the isolation between the antenna radiation ends 2 is improved. A plurality of second extension branches 33 are disposed in the semi-enclosed structure 32 to implement multi-frequency filtering.

Referring to fig. 1 and fig. 2, by optimizing parameters such as the length of the first extension branch 31, the position and the length of the second extension branch 33, good isolation of the antenna in this embodiment can be achieved when the antenna works in the frequency band of 1.8Ghz-3.1Ghz, fig. 1 is a schematic diagram of an optimized MIMO antenna structure, the impedance frequency band width of the antenna is 1.86 Ghz (1.24 Ghz-3.10 Ghz), the relative bandwidth of the antenna is 42.9%, and the working frequency band includes frequency points such as GSM 1.9 Ghz, wi-Fi 2.4 Ghz, bluetooth 2.4 Ghz, and FDD LTE 2.5-2.7 Ghz in intelligent terminal communication. The maximum radiation direction of the antenna is in both directions normal to the plane and enables uniform omnidirectional radiation in both directions. Fig. 2 is a schematic diagram of a frequency-dependent change curve of an S parameter obtained by simulating the whole MIMO antenna by using simulation software, and it can be seen from the graph that the coupling degree of the antenna structure in the frequency band of 1.24 GHz-3.10 GHz is lower than-19.2 dB, so that the requirement of less than-15 dB in engineering can be completely satisfied. The two unit antennas have uniform radiation characteristics in the normal direction of the plane, and the radiation in the main polarization direction is far greater than the radiation in the cross polarization direction, so that the two antennas have good cross polarization isolation.

Referring to fig. 1, the antenna radiation end 2 is a monopole radiation patch printed on the dielectric substrate 1, and the bandwidth of the antenna can be relatively wide, so as to realize radiation and reception of the frequency band of 1.8GHz-3.1 GHz. The radiation end 2 of the antenna is preferably an F-shaped metal patch. The first extension branch 31, the semi-closed structure 32 and the second extension branch 33 of the filtering decoupling network 3 also adopt metal patch structures on the dielectric substrate 1, and similarly, the grounding plate is a metal patch printed on the dielectric substrate 1, so as to form a microstrip antenna. The dielectric substrate 1 is an FR4 substrate with a dielectric constant of 4.4±3%. The feed point of the antenna radiation end 2 is connected with a 50 ohm feed microstrip line 4, and a signal line of a radiation system of an intelligent terminal such as a mobile phone can be directly connected with the feed microstrip lines of the two microstrip antennas.

Fig. 1 shows a conventional MIMO antenna, which includes two symmetrically arranged antenna radiation ends 2, both of which can achieve broadband radiation. The polarization of both monopole antennas is linear, and the other characteristics of both antennas are substantially the same. The filtering decoupling network 3 is arranged between the two antenna radiation ends 2, and a filtering decoupling network is added between the two antenna radiation ends, and the filtering decoupling network is similar to a broadband filter, can work in a specific frequency range, and reduces the coupling between the antennas. In practice, more than two antenna radiation ends 2 may be provided as needed, and a filtering decoupling network 3 is provided between each antenna radiation end 2.

It is to be understood that the above examples of the present invention are provided by way of illustration only and not by way of limitation of the embodiments of the present invention. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the invention are desired to be protected by the following claims.

Claims

1. A high isolation MIMO antenna, characterized by: the antenna comprises a dielectric substrate (1), at least two antenna radiation ends (2), a filtering decoupling network (3) and a grounding plate, wherein the antenna radiation ends (2) and the filtering decoupling network (3) are arranged on one surface of the dielectric substrate (1), and the grounding plate is arranged on the other surface of the dielectric substrate (1); the filtering decoupling network (3) is connected between the antenna radiation ends (2); the filtering decoupling network (3) comprises first extending branches (31) and semi-closed structures (32), each antenna radiation end (2) extends to a position between each antenna radiation end to form a first extending branch (31), each first extending branch (31) extends into the semi-closed structures (32) from an opening of each semi-closed structure (32), and a plurality of second extending branches (33) are arranged in each semi-closed structure (32); the grounding plate is a metal patch printed on the dielectric substrate (1).

2. The high isolation MIMO antenna of claim 1 wherein: the antenna radiation end (2) is a monopole radiation patch printed on the dielectric substrate (1).

3. The high isolation MIMO antenna of claim 2 wherein: the antenna radiation end (2) is an F-shaped metal patch.

4. The high isolation MIMO antenna of claim 1 wherein: the dielectric substrate (1) is an FR4 substrate with a dielectric constant of 4.4+/-3%.

5. The high isolation MIMO antenna of claim 1 wherein: and a 50 ohm feed microstrip line (4) is connected at a feed point of the antenna radiation end (2).

6. The high-isolation MIMO antenna according to any one of claims 1-5, wherein: the antenna radiation end (2) is symmetrically arranged, and the filtering decoupling network (3) is arranged between the two antenna radiation ends (2).