CN110854529B

CN110854529B - Compact low-coupling tri-polarization MIMO antenna based on plane structure

Info

Publication number: CN110854529B
Application number: CN201911113327.9A
Authority: CN
Inventors: 朴大志; 左杰; 张林坤; 王亚金
Original assignee: Communication University of China
Current assignee: Communication University of China
Priority date: 2019-11-14
Filing date: 2019-11-14
Publication date: 2021-11-05
Anticipated expiration: 2039-11-14
Also published as: CN110854529A

Abstract

The invention discloses a compact low-coupling triple-polarization MIMO antenna based on a planar structure, which belongs to the field of antennas of communication technologies and is formed by stacking two layers of dielectric plates, wherein a main radiator metal patch covers the top surface of an upper layer of dielectric plate, a grounding metal plate is arranged on the bottom surface of a lower layer of dielectric plate, a parasitic metal patch is arranged between the two layers of dielectric plates, a plurality of first metal through holes for connecting the parasitic metal patch and the main radiator metal patch are arranged in the upper layer of dielectric plate, and a plurality of second metal through holes for connecting the main radiator metal patch and the grounding metal plate are arranged in the two layers of dielectric plates. And feeding is carried out at different positions of the main radiator metal patch of the antenna, so that three orthogonal polarizations can be realized at the same frequency. Compared with the existing triple-polarization MIMO antenna, the triple-polarization MIMO antenna has smaller size and lower coupling, is more suitable for small-sized terminal equipment, is more suitable for forming an antenna array, and can also be used as a unit of a compact large-scale MIMO antenna.

Description

Compact low-coupling tri-polarization MIMO antenna based on plane structure

Technical Field

The invention designs a compact low-coupling triple-polarization MIMO antenna based on a planar structure, and belongs to the field of antennas of communication technologies.

Background

The fifth generation communication technology which is already in commercial use shows that the forward speed of the mobile communication is faster, the error rate is lower, the time delay is shorter and the channel capacity is higher. In a wireless communication system, a plurality of antennas are simultaneously used at a transmitting end and a receiving end, that is, a Multiple-Input Multiple-Output (MIMO) technology is used, so that the communication system has advantages of stable transmission, increased channel capacity and the like.

In the prior art, a MIMO antenna has been disclosed, in which a certain number of metal vias connecting metal patches and a ground metal plate are added to realize that the same radiator generates three orthogonally polarized antennas. Although this antenna achieves triple polarization by a single-layer compact structure, there are two disadvantages: the antenna size is larger than half a wavelength and the coupling is larger than-13 dB.

As the terminal and base station devices used by 5G are smaller, the demand for miniaturization of MIMO antennas is also increasing in communication devices and related fields. However, miniaturization can cause problems for MIMO antennas, such as increased coupling between antenna elements, which can affect the radiation characteristics of the MIMO antenna. Therefore, how to make the MIMO antenna achieve both miniaturization and low coupling becomes one of the key problems in the design of the MIMO antenna array.

Adding parasitic patches is a common way to improve antenna performance, which can increase bandwidth or increase gain. The addition of the parasitic patch, however, generally increases the size of the antenna in either the vertical or horizontal direction. For example, application 201310121176.8 proposes a microstrip antenna loaded with a parasitic ring, which reduces zenith signal radiation of a conventional microstrip patch antenna and increases low elevation gain near a horizontal plane, thereby widening lobe width of a vertical plane, and the antenna is composed of two dielectric plates separated by a certain distance using a fixing post, resulting in a high overall profile. Application No. 201620584674.5 is to add two parasitic patches with kitchen knife-shaped slots between two antenna radiation units, and change the electric field distribution on the antenna radiation units by changing the charge distribution on the dielectric plate, so as to achieve the purpose of reducing the coupling degree between the antenna radiation units, however, the two radiation units of the structure are separated by a distance on the horizontal plane, and the horizontal size is larger.

These designs of loading the antenna with the parasitic patch increase the cross-sectional height or the plane size of the antenna, which is not favorable for realizing the miniaturization of the antenna or forming an array antenna.

Disclosure of Invention

In view of the above problems in the prior art, an object of the present invention is to provide a compact low-coupling triple-polarized MIMO antenna based on a planar structure.

In order to solve the technical problems, the specific technical scheme of the invention is as follows:

the invention designs a compact low-coupling tri-polarization MIMO antenna based on a planar structure by changing the equivalent path length of current. Through adding parasitic metal paster and the metal via hole of connecting parasitic metal paster and main radiator metal paster to and the metal via hole of connecting ground connection metal sheet and main radiator, make the resonant frequency of vertical polarization's electric field mode reduce, the isolation between the different excitation ports improves, finally obtains the radiation pattern of three mutual quadrature under the same resonant frequency: when the first port feeds power, the antenna excites a vertically polarized electric field, and when the second port and the third port feed power, the antenna excites two horizontal polarized electric fields which are orthogonal to each other, so that a triple polarized antenna is formed.

In the invention, the metal through hole for connecting the main radiator metal patch and the parasitic metal patch is added, so that the current on the main radiator metal patch is introduced into the parasitic metal patch, and the equivalent path of the current is increased in a compact structure, thereby achieving the purposes of reducing the size and the resonant frequency. With the change of current distribution by the new structure, the coupling degree between different ports of the antenna is also reduced.

The invention has the advantages that:

the invention provides a compact low-coupling tri-polarization MIMO antenna based on a planar structure for the first time, wherein the antenna structure comprises a grounding metal plate, two dielectric plates, a main radiator metal patch, a parasitic metal patch, a plurality of metal through holes for connecting the main radiator metal patch and the grounding metal plate, and three feed ports. The parasitic metal patch and the metal via hole are used for achieving the purposes of reducing the size of the antenna, reducing the height of the section and reducing coupling.

Drawings

In order to more clearly illustrate the technical solution of the present invention, the drawings used in the description of the embodiment or the prior art will be briefly described below. It is obvious that the drawings in the following description are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.

Fig. 1 is a top view of a compact low-coupling triple-polarized MIMO antenna based on a planar structure in an embodiment of the present invention.

Fig. 2 is a side view of the antenna of fig. 1.

Fig. 3 is a simulation result of S parameter in the embodiment of the present invention.

Fig. 4(a) and 4(b) are xoy plane and xoz plane radiation patterns, respectively, when the triple polarized antenna first port 11 in the embodiment of the present invention is fed.

Fig. 5 is an electric field distribution diagram when the first port 11 of the triple polarized antenna in the embodiment of the present invention is fed.

Fig. 6(a) and 6(b) are xoz plane and yoz plane radiation patterns, respectively, when the second port 10 of the triple polarized antenna in the embodiment of the present invention is excited.

Fig. 7 is an electric field distribution diagram when the triple polarized antenna of the embodiment of the present invention is fed through the second port 10.

Fig. 8(a) and 8(b) are xoz plane and yoz plane radiation patterns, respectively, when the triple polarized antenna third port 01 is excited in the embodiment of the present invention.

Fig. 9 is an electric field distribution diagram when the third port 01 of the triple polarized antenna in the embodiment of the present invention is fed.

Fig. 10 is the simulation result of S11 before and after adding the circular metal patch 4 and the first metal via 5 according to the embodiment of the present invention.

Fig. 11(a) and (b) show surface current distributions of the main radiator metal patch and the parasitic metal patch when the triple polarized antenna in the embodiment of the present invention is excited at the first port 11.

Fig. 12 shows simulation results of S12 and S13 before and after adding the circular metal patch 4 and the first metal via 5 according to the embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, apparatus, article, or device 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 device.

Example 1

Referring to fig. 1 and 2, the antenna is composed of a double-layer dielectric plate 1, a grounding metal plate 2, a circular metal patch 3, a circular metal patch 4, twelve first metal via holes 5 connecting the circular metal patch 3 and the circular metal patch 4, eight second metal via holes 6 connecting the circular metal patch 3 and the grounding metal plate 2, and three coaxial

line feed ports

10, 01, and 11.

The double-layer dielectric plates 1 are made of the same material, are all epoxy resin plates FR4 with the dielectric constant of 4.4, are stacked on the xoy surface by taking the original point as the center, and have the side length of 42mm which is less than the half wavelength corresponding to 3.5 GHz; the grounding metal plate 2 is positioned on the bottom surface of the lower dielectric plate and has the same size as the bottom area of the lower dielectric plate; the circular metal patch 3 is covered on the top surface of the upper dielectric slab and is used as a main radiator; the round metal patch 4 is arranged between the two layers of dielectric slabs and is used as a parasitic patch; the centers of the circular metal patch 3 and the circular metal patch 4 are on the same z axis; the first metal via holes 5 are symmetrically arranged on the xoy plane around the z axis, the included angle between each adjacent via hole and the original point is 30 degrees, the radius of each via hole is equal, the distance from each via hole to the original point is also equal, and each via hole penetrates through the upper dielectric plate and is connected with the circular metal patch 3 and the circular metal patch 4; the second metal via holes 6 are symmetrically arranged on the xoy plane around the z axis, the included angle between each adjacent via hole and the original point is 45 degrees, the radius of each via hole is equal, the distance from each via hole to the original point is also equal, and each via hole penetrates through the two layers of dielectric plates and is connected with the circular metal patch 3 and the grounding metal plate 2; the first metal via 5 is inside the second metal via 6; the three feeding ports are all fed by SMA coaxial lines with characteristic impedance of 50 omega, the first feeding port 11 penetrates through the circular metal patch 4 and is excited in the center of the circular metal patch 3, the distance between the second feeding port 10 and the third feeding port 01 and the center of the circular metal patch 3 is equal, the distance is larger than the radius of the circular metal patch 4 and smaller than the distance between the second metal via hole 6 and the center of the circular metal patch 3, and the second feeding port 10 and the third feeding port 01 are excited in the x-axis position and the y-axis position on the circular metal patch 3 respectively.

Fig. 3 shows the simulation result of the S-parameters of the antenna, where the three polarized resonant frequency bands coincide, the operating band of the monopole antenna is 3.45-3.56GHz and the bandwidth is 110MHz, and the operating band of the microstrip antenna is 3.45-3.56GHz and the bandwidth is 110 MHz.

When fed at the first port 11, the antenna produces the radiation characteristic of a monopole antenna. Fig. 4(a) and 4(b) show a xoy plane radiation pattern and an xoz plane radiation pattern, respectively, at 3.5GHz when the antenna is excited at the first feed port 11, and the antenna is polarized along the z-axis. Fig. 5 shows the electric field distribution when the first port 11 feeds power, the electric field is bounded by the first metal via 5, the electric field inside the via is vertically downward, the electric field outside the via is vertically upward, and the TM02 monopole radiation pattern is formed.

When fed at the second port 10, the antenna produces the radiation characteristic of a microstrip antenna. Fig. 6(a) and 6(b) show xoz plane and yoz plane radiation patterns, respectively, at 3.5GHz when the second feed port 10 of the antenna is excited, with the antenna polarized along the x-axis. Fig. 7 is an electric field distribution when the second port 10 is fed, which is in antiphase symmetry with respect to the y-axis.

When fed at the third port 01, the antenna produces the radiation characteristic of a microstrip antenna. Fig. 8(a) and 8(b) show xoz plane radiation patterns and yoz plane radiation patterns at 3.5GHz when the third feed port 01 of the antenna is excited, respectively, and the antenna is polarized along the y-axis. Fig. 9 is an electric field distribution when the third port 01 is fed, which is in antiphase symmetry with respect to the x-axis.

To better illustrate the invention, some comparisons are made next. As can be seen from fig. 10, the S11 resonant frequency of the antenna, representing TM02 monopole radiation mode, was reduced from 4.2GHz to 3.5GHz after the addition of the circular metal patch 4 and the first metal via 5 as parasitic patches. As can be seen from fig. 11, when the first feeding port 11 of the antenna is excited, the first metal via 5 introduces the surface current of the circular metal patch 3 into the circular metal patch 4, and the equivalent current path is increased, so that the resonant frequency of S11 is reduced to 3.5 GHz. As can be seen from fig. 12, after the circular metal patch 4 and the first metal via 5 are added, the coupling between the antenna ports is reduced to below-18 dB.

In summary, the parasitic metal patch and the specific metal via hole are added in the co-point orthogonal triple-polarization MIMO antenna, so that the coupling between the three ports of the antenna is reduced to below-18 dB without increasing the profile height, and the size of the antenna is smaller than half a wavelength, thereby providing a solution for forming the antenna array.

While the invention has been described with reference to specific embodiments, it will be appreciated by those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the invention can be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.

Claims

1. The utility model provides a compact low coupling tripolar MIMO antenna based on planar structure which characterized in that: the antenna comprises a grounding metal plate, two layers of dielectric plates, a main radiator metal patch, a parasitic metal patch, a plurality of first metal through holes, a plurality of second metal through holes, a first feed port, a second feed port and a third feed port; the first feed port is positioned in the center of the main radiator metal patch and penetrates through the parasitic metal patch to excite the main radiator metal patch; the second feed port and the third feed port are positioned on the outer side of the parasitic metal patch, form an included angle of 90 degrees with a circle center connecting line of the parasitic metal patch and are used for exciting two positions of the main radiator metal patch;

the main radiator metal patch and the grounding metal plate are provided with a parasitic metal patch, the main radiator metal patch and the parasitic metal patch are connected through a plurality of first metal via holes, the outer side of the parasitic metal patch is provided with a plurality of second metal via holes for connecting the main radiator metal patch and the grounding metal plate, so that the isolation between different excitation ports is improved, the resonant frequency of a vertically polarized electric field mode is reduced, three mutually orthogonal radiation modes under the same resonant frequency are obtained, namely, two microstrip antenna radiation modes and a TM02 monopole antenna radiation mode, specifically two horizontally polarized electric fields and one vertically polarized electric field, and a triple polarized antenna is formed.

2. The compact low-coupling tri-polarization MIMO antenna based on planar structure of claim 1, wherein: the two layers of dielectric plates adopt a stacked structure, the materials of the dielectric plates are the same, and the thicknesses of the dielectric plates are the same.

3. The compact low-coupling tri-polarization MIMO antenna based on planar structure of claim 1, wherein: the two layers of dielectric slabs comprise an upper layer dielectric slab and a lower layer dielectric slab, the main radiator metal patch is arranged on the top surface of the upper layer dielectric slab, the parasitic metal patch is arranged between the upper layer dielectric slab and the lower layer dielectric slab, and the grounding metal slab is arranged on the bottom surface of the lower layer dielectric slab.

4. The compact low-coupling tri-polarization MIMO antenna based on planar structure of claim 1, wherein: the main radiator metal patch and the parasitic metal patch are both circular metal patches.

5. The compact low-coupling tri-polarized MIMO antenna based on planar structure as claimed in claim 4, wherein: the center of the parasitic metal patch and the center of the main radiator metal patch are in the same vertical direction, and the size of the parasitic metal patch is smaller than that of the main radiator metal patch.

6. The compact low-coupling tri-polarization MIMO antenna based on planar structure of claim 1, wherein: 12 first metal through holes for connecting the parasitic metal patch and the main radiator metal patch are arranged, penetrate through the upper-layer dielectric plate, have the same radius and are symmetrically arranged relative to the center of the parasitic metal patch.

7. The compact low-coupling tri-polarization MIMO antenna based on planar structure of claim 1, wherein: and 8 second metal through holes for connecting the grounding metal plate and the main radiator metal patch are arranged, penetrate through the two dielectric plates, have the same radius, are positioned on the outer side of the parasitic metal patch and are symmetrically arranged relative to the center of the main radiator metal patch.