MIMO Antenna Isolation via Slit and Ground Structures
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Solution Overview
Problem
The challenge in designing communications terminals with metal bodies is to achieve high compactness and isolation between multiple-input multiple-output (MIMO) antennas while maintaining effective directivity patterns and radiation performance, especially when frequency bands overlap and space is limited.
Innovation Solution
A modular antenna design with slits and ground structures is implemented, where each antenna module includes radiators and slits to enhance isolation, and band-pass filters are used to separate frequency bands, forming multi-feed antenna configurations to improve directivity and reduce design complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If MIMO antennas are added to a metal-body terminal, then antenna functionality is improved, but isolation between antennas deteriorates
Solution Approach 1:
The antenna system is divided into multiple independent antenna modules, each with its own radiator and ground structure. The metal frame is segmented with slits to create isolated antenna elements, allowing each module to operate independently while maintaining overall system functionality.
Solution Approach 2:
Ground structures are introduced as intermediary elements between adjacent antennas to improve isolation. These ground structures act as mediators that block electromagnetic coupling between antenna elements while maintaining the required electrical connections.
2Adaptability or versatility
If antenna quantity increases from 2*2 to 4*4, then communication performance is improved, but space compactness deteriorates
Solution Approach 1:
The antenna elements are arranged in a three-dimensional configuration within the terminal body, utilizing vertical and lateral dimensions to accommodate multiple antennas. The metal frame structure provides spatial separation in multiple dimensions while maintaining a compact overall form factor.
Solution Approach 2:
Multiple antenna elements are nested within the metal frame structure, with radiators positioned in different layers and orientations. This nested arrangement allows four antenna elements to be compactly integrated within the terminal's limited space.
3Productivity
If frequency bands are made the same for MIMO and original antennas, then spectrum utilization is improved, but isolation between antenna systems deteriorates
Solution Approach 1:
Different regions of the antenna system are designed with locally optimized characteristics for their specific frequency bands. The metal frame and ground structures are configured to provide frequency-selective isolation, allowing same-band operation while maintaining adequate separation through localized electromagnetic shielding.
4Reliability
If directivity pattern requirements are increased, then transmission feature is improved, but design complexity deteriorates
Solution Approach 1:
Multiple antenna elements are combined in a MIMO configuration where their collective radiation patterns achieve the desired directivity characteristics. By merging the functionality of multiple simpler antenna elements, the system achieves complex transmission features without designing each individual antenna with high complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively increases isolation between MIMO antennas, enhances directivity patterns, and optimizes radiation performance, allowing for better multi-carrier aggregation in LTE frequency bands, even in compact metal-body terminals.
Implementation Method 1
a first slit is provided between the first radiator and the second radiator... to increase isolation between the first antenna module and the second antenna module
Implementation Method 2
one end of the first ground structure is connected to at least one of the second radiator and the third radiator, and another end is connected to at least one ground plane of the communications terminal, to increase isolation between the first antenna module and the second antenna module
Data Source
Figure 1
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Figure 5~6
AI summary
Embodiments of the present invention disclose a communications terminal, including a multiple-input multiple-output antenna system. The multiple-input multiple-output antenna system includes a first antenna module, a second antenna module, and a first ground structure. The first antenna module includes a first radiator and a second radiator, and a first slit is provided between the first radiator and the second radiator. The second antenna module includes a third radiator and a fourth radiator. The second radiator is connected to the third radiator. The first radiator is configured to form a first MIMO antenna, the second radiator is configured to form a GPS antenna, the third radiator is configured to form a first low frequency communications antenna, and the fourth radiator is configured to form a second MIMO antenna. One end of the first ground structure is connected to at least one of the second radiator and the third radiator, and another end is connected to a ground plane of the communications terminal, to increase isolation between the first antenna module and the second antenna module. Based on the communications terminal, isolation between antenna modules can be effectively improved.