Compact MIMO Antenna Branch Layout for Higher Isolation
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Solution Overview
Problem
In terminal devices with highly compressed spaces, such as those using a full-screen structure with an ultra-narrow frame, the addition of multiple antennas for MIMO communication reduces isolation between antennas, leading to degraded performance and communication quality due to mutual coupling.
Innovation Solution
An antenna system is designed with a third radiation branch that acts as a suspended parasitic branch, forming differential-mode currents to cancel out currents on existing branches, reducing mutual coupling and improving isolation, while also supporting both high and medium-frequency bands through strategic tuning circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single antenna structure is used to support multiple protocols (Sub-6 GHz and mmWave), then device integration is improved, but antenna performance and communication reliability deteriorate due to frequency band conflicts and isolation issues
Solution Approach 1:
The antenna system is segmented into a first antenna for Sub-6 GHz protocols and a second antenna for mmWave protocols, with each antenna independently optimized for its specific frequency band. This segmentation eliminates frequency band conflicts and isolation issues while maintaining device integration through coordinated operation of the segmented components.
Solution Approach 2:
A switching module acts as an intermediary between the protocol stack and the segmented antennas, selectively connecting the appropriate antenna to the transceiver based on the active communication protocol. This intermediary ensures that each antenna operates in its optimal frequency range without interference from the other protocol.
2Ease of manufacture
If antenna elements are arranged in specific patterns (e.g., uniform linear array) to simplify design, then manufacturing ease is improved, but beamforming flexibility and MIMO performance deteriorate
Solution Approach 1:
The antenna elements within each antenna are arranged in asymmetric patterns rather than uniform arrays, with specific spacing and positioning optimized for both beamforming capabilities and MIMO operations. This asymmetric arrangement provides flexibility in controlling signal directions and patterns while maintaining manufacturability through standardized component placement.
3Volume of moving object
If antenna elements are placed close together to reduce device size, then compactness is improved, but element isolation deteriorates causing mutual interference
Solution Approach 1:
By segmenting the antenna system into frequency-specific antennas (Sub-6 GHz and mmWave), the patent eliminates mutual interference between elements operating at different frequencies, allowing elements to be placed closer together within each segmented antenna without suffering from cross-frequency interference.
Solution Approach 2:
Each antenna element is designed with local quality optimizations including specific ground structure configurations and positioning relative to the device chassis, which enhance isolation between elements while maintaining compact dimensions. The grounding system is locally optimized to provide shielding and reduce interference.
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
The solution enhances antenna performance and communication quality by increasing isolation between radiation branches, particularly in the high-frequency band, and expands the antenna system's bandwidth to include medium-frequency bands.
Implementation Method 1
an antenna system including a first antenna configured to support a first protocol of a set of communication protocols operating on a first frequency band, and a second antenna configured to support a second protocol of the set of communication protocols operating on a second frequency band
Data Source
Figure 1a~1c
Figure 2a~2b
Figure 3
AI summary
This application relates to the field of antenna technologies, and provides an antenna system and a terminal device. The antenna system includes: a first radiation branch, a second radiation branch and a third radiation branch, where the first radiation branch and the second radiation branch are electrically connected, and a first gap is provided between the second radiation branch and the third radiation branch; a first feed point is disposed on the first radiation branch, and the first feed point is located at an end of the first radiation branch away from the second radiation branch; a second feed point is disposed on the second radiation branch, and the second feed point is located at an end of the second radiation branch away from the first radiation branch; the antenna system further includes: a first ground return point, where the first ground return point is located at an electrical connection between the first radiation branch and the second radiation branch, and the first ground return point is located between the first feed point and the second feed point; and a second ground return point is disposed on the third radiation branch, and the second ground return point is located at an end of the third radiation branch away from the first gap. Isolation between antennas is improved in the antenna system.