CN108336490B

CN108336490B - High-isolation broadband MIMO antenna

Info

Publication number: CN108336490B
Application number: CN201810185010.5A
Authority: CN
Inventors: 陈付昌; 钱建锋
Original assignee: South China University of Technology SCUT
Current assignee: South China University of Technology SCUT
Priority date: 2018-03-07
Filing date: 2018-03-07
Publication date: 2023-08-22
Anticipated expiration: 2038-03-07
Also published as: CN108336490A

Abstract

The invention discloses a high-isolation broadband MIMO antenna, which comprises a first dielectric substrate, a second dielectric substrate, a metal floor, four patch radiating units and four input ports, wherein the first dielectric substrate is arranged on the metal floor; the first medium substrate is positioned above the second medium substrate, and an air layer is reserved between the first medium substrate and the second medium substrate; the four patch radiating units are rotationally symmetrically arranged on the top surface of the first dielectric substrate about the center, each patch radiating unit comprises a concave parasitic patch, a rectangular patch with half wavelength and a convex parasitic patch, the concave parasitic patch and the convex parasitic patch are respectively coupled to two opposite sides of the rectangular patch in parallel, the metal floor is arranged on the top surface of the second dielectric substrate and provided with four gaps, and microstrip feeder lines of four input ports are arranged on the bottom surface of the second dielectric substrate and excite the corresponding rectangular patch through the gaps. The invention can realize good impedance matching, isolation and radiation characteristics, does not need an additional decoupling structure, and has the advantages of low profile, low cross polarization, low cost and the like.

Description

High-isolation broadband MIMO antenna

Technical Field

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

Background

The MIMO system, i.e. the MIMO system, can increase the communication capacity by a multiple number of times by providing a plurality of transmitting and receiving antennas and performing specific data processing, thereby meeting the current increasing demands for communication services. In most of the existing MIMO systems, most of the MIMO antennas are designed with respect to narrowband antenna units, and the isolation between the antenna units can only be satisfied within a very narrow frequency range. And in order to reduce mutual coupling between the antenna elements, it is generally necessary to add an additional decoupling structure or to increase the distance between the antenna elements. Additional decoupling structures often introduce unwanted degradation in radiation performance and with the current trend toward miniaturization of electronics, decoupling approaches that increase the distance between antenna elements are also undesirable.

The prior art is investigated and known, and the specific steps are as follows:

in 2016, hongye Qi et al published under the heading "IEEE ANTENNAS WIRELESS PROPAGATION LETTER" as "Improving isolation between closely spaced patch antennas using interdigital lines", where a band stop structure was introduced by adding a shorting stub between two rectangular patches to reduce the mutual coupling between the two antenna elements. By using three short stubs, the MIMO antenna herein achieves an isolation of greater than 20dB. However, due to the strong currents on the decoupling structure, both the reflection coefficient and the radiation pattern of the antenna are deteriorated to different extents.

In 2017, seahe Hwangbo et al published under the heading "IEEE ANTENNAS WIRELESS PROPAGATION LETTER" Mutual Coupling Reduction Using Micromachined Complementary Meander-Line Slots for a Patch Array Antenna "where mutual coupling between antenna elements was reduced by digging a plurality of symmetrical meander lines into the floor. The slot lines on the floor have the selective effect of a band stop, increasing the isolation between the antenna elements, but these slot lines introduce unnecessary reflection zeroes in the reflection coefficient. The radiation patterns tested herein are also affected to some extent.

In general, there is much research on MIMO antennas in existing work, but most are designs focusing on narrowband antenna elements, and in general, additional decoupling structures are required to enhance isolation. The design of the MIMO antenna with wide impedance bandwidth and good radiation characteristic has important significance.

Disclosure of Invention

The invention aims to overcome the defects of the prior art, and provides a high-isolation broadband MIMO antenna with a compact structure, which can realize good impedance matching, isolation and radiation characteristics, does not need an additional decoupling structure, and has the advantages of flexible design, low profile, low cross polarization, low cost and the like.

In order to achieve the above purpose, the technical scheme provided by the invention is as follows: a high-isolation broadband MIMO antenna comprises a first dielectric substrate, a second dielectric substrate, a metal floor, four identical patch radiating units and four input ports corresponding to the four patch radiating units one by one; the first medium substrate is positioned above the second medium substrate, and an air layer is reserved between the first medium substrate and the second medium substrate; the four patch radiating units are arranged on the top surface of the first dielectric substrate in a rotationally symmetrical manner about the center, two adjacent patch radiating units are mutually perpendicular, each patch radiating unit comprises a concave parasitic patch, a rectangular patch with half wavelength and a convex parasitic patch, the concave parasitic patch and the convex parasitic patch are respectively coupled on two opposite sides of the rectangular patch in parallel so as to obtain broadband characteristics, and the convex of the convex parasitic patch faces to the groove position of the concave parasitic patch; the metal floor is arranged on the top surface of the second medium substrate and is provided with four gaps corresponding to the four patch radiating units one by one, and the microstrip feeder lines of the four input ports are arranged on the bottom surface of the second medium substrate and excite the rectangular patches of the corresponding patch radiating units through the four gaps on the metal floor.

The resonant frequency of the concave parasitic patch is lower than that of the rectangular patch, and the resonant frequency of the convex parasitic patch is higher than that of the rectangular patch.

The input port is a 50 ohm impedance match.

Compared with the prior art, the invention has the following advantages and beneficial effects:

1. the MIMO antenna can realize higher isolation without redundant decoupling structures due to different maximum current positions of the used broadband units at different resonance frequencies.

2. The directivity pattern of the MIMO antenna achieves good side-fire characteristics and good impedance matching in the passband, since no additional decoupling structure is used.

3. The high-isolation broadband MIMO antenna has the advantages of simple and compact structure, simple processing, light weight, low processing cost and good application prospect.

Drawings

Fig. 1 is a perspective view of a high isolation wideband MIMO antenna of the present invention.

Fig. 2 is a top view of a high isolation wideband MIMO antenna of the present invention.

Fig. 3 is a simulation result of the reflection coefficient and isolation of the high-isolation wideband MIMO antenna of the present invention.

Fig. 4 is a normalized radiation pattern (H-plane and E-plane) simulation result of the high isolation wideband MIMO antenna of the present invention at the center frequency of the operating passband.

Detailed Description

The invention will be further illustrated with reference to specific examples.

Referring to fig. 1 and 2, the high-isolation wideband MIMO antenna provided in this embodiment includes a first dielectric substrate 1, a second dielectric substrate 2, a metal floor 3, four identical patch radiating units 4, and four input ports corresponding to the four patch radiating units 4 one by one; the first medium substrate 1 is positioned above the second medium substrate 2, and an air layer 5 is reserved between the first medium substrate and the second medium substrate; the four patch radiating units 4 are rotationally symmetrically arranged on the top surface of the first dielectric substrate 1 about the center to obtain sufficient isolation, and two adjacent patch radiating units 4 are mutually perpendicular, each patch radiating unit 4 comprises a concave parasitic patch 401, a rectangular patch 402 with half wavelength and a convex parasitic patch 403, the concave parasitic patch 401 and the convex parasitic patch 403 are respectively coupled with two opposite sides of the rectangular patch 402 in parallel to obtain broadband characteristics, and the convex of the convex parasitic patch 403 faces to the groove position of the concave parasitic patch 401; the metal floor 3 is disposed on the top surface of the second dielectric substrate 2, four slots 31 corresponding to the four patch radiating units 4 one by one are formed on the metal floor 3, and the microstrip feeder lines 6 of the four input ports are disposed on the bottom surface of the second dielectric substrate 2, and the rectangular patches 402 of the corresponding patch radiating units 4 are excited by the four slots 31 on the metal floor 3. The four input ports are all 50 ohm impedance matched, the dielectric constants of the first dielectric substrate 1 and the second dielectric substrate 2 are all 2.55, the loss tangent is 0.0029, and the thicknesses are all 0.8 millimeter; the distance between every two patch radiating elements 4 is 0.09 lambda ₀ Wherein lambda is ₀ Free space wavelength; the thickness of the air layer 5 is designed to be 1 mm.

Referring to fig. 3, simulation results of the reflection coefficient and isolation of the high-isolation wideband MIMO antenna according to the present embodiment are shown. As can be seen from the figure, the antenna achieves a good impedance match within the passband and the isolation between the patch radiating elements S31 and S21 is greater than 20dB. A plurality of transmission zeroes appear on both isolation curves S31 and S21, which greatly reduces the mutual coupling between patch radiating elements.

Referring to fig. 4, the simulation results of the normalized radiation patterns of the E plane and the H plane of the high-isolation wideband MIMO antenna of the present embodiment at the center frequency of the passband are shown. It can be seen from the figure that the antenna achieves good directional radiation characteristics in both the E-plane and the H-plane, and that the cross polarization in the broadside direction is lower than-30 dBi. Therefore, the antenna has good application prospect and is worthy of popularization.

The above embodiments are only preferred embodiments of the present invention, and are not intended to limit the scope of the present invention, so variations in shape and principles of the present invention should be covered.

Claims

1. A high isolation wideband MIMO antenna, characterized by: the patch antenna comprises a first dielectric substrate, a second dielectric substrate, a metal floor, four identical patch radiating units and four input ports corresponding to the four patch radiating units one by one; the first medium substrate is positioned above the second medium substrate, and an air layer is reserved between the first medium substrate and the second medium substrate; the four patch radiating units are arranged on the top surface of the first dielectric substrate in a rotationally symmetrical manner about the center, two adjacent patch radiating units are mutually perpendicular, each patch radiating unit comprises a concave parasitic patch, a rectangular patch with half wavelength and a convex parasitic patch, the concave parasitic patch and the convex parasitic patch are respectively coupled on two opposite sides of the rectangular patch in parallel so as to obtain broadband characteristics, and the convex of the convex parasitic patch faces to the groove position of the concave parasitic patch; the metal floor is arranged on the top surface of the second medium substrate and provided with four gaps which are in one-to-one correspondence with the four patch radiating units, and the microstrip feeder lines of the four input ports are arranged on the bottom surface of the second medium substrate and excite the rectangular patches of the corresponding patch radiating units through the four gaps on the metal floor; the resonance frequency of the concave parasitic patch is lower than that of the rectangular patch, and the resonance frequency of the convex parasitic patch is higher than that of the rectangular patch; the input port is a 50 ohm impedance match.