Antenna Unit Series Decoupling for MIMO Isolation
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Solution Overview
Problem
In mobile terminals, achieving high isolation between antennas is challenging due to physical size constraints and limited effectiveness of traditional methods, especially for low-frequency bands, which hampers the performance of 4×4 MIMO antenna systems.
Innovation Solution
An antenna unit comprising an antenna circuit board with at least two neighboring antennas and an electromagnetic coupling module connected in series, utilizing an isolation metal structure and lumped parameter elements to reduce signal coupling between antennas, thereby improving isolation across a wider frequency band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the spacing between antennas is increased to reduce correlation and improve isolation, then antenna isolation is improved, but terminal physical size increases
Solution Approach 1:
The patent introduces a decoupling network as an intermediary component between adjacent antennas. This decoupling network acts as a mediator that blocks coupling signals from propagating between antennas, thereby improving isolation without requiring increased physical spacing. The decoupling network is connected in series between antenna ports and serves as a signal path controller that prevents harmful electromagnetic coupling while maintaining compact terminal dimensions.
2Reliability
If traditional decoupling methods (parasitic metal conductors, decoupling lines) are used to improve antenna isolation, then isolation is improved for high frequency bands, but the decoupling bandwidth becomes narrow and ineffective for low frequency bands
Solution Approach 1:
The patent employs parameter changes by using lumped parameter elements (inductors and capacitors) within the decoupling network that can be tuned to achieve effective decoupling across different frequency bands. By adjusting the values of these lumped parameters, the decoupling network can adapt its characteristics to provide effective isolation for both low frequency bands (such as LTE Band 12, 13, 17) and high frequency bands, thereby expanding the operational bandwidth beyond what traditional fixed-structure decoupling methods can achieve.
3Productivity
If four antennas are deployed for 4×4 MIMO technology to increase transmission rate, then channel capacity is improved, but antenna correlation increases and isolation deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the antenna system into independent units with dedicated decoupling networks between each adjacent antenna pair. This segmentation approach allows each antenna to be treated as an independent radiating element with controlled coupling characteristics. By implementing decoupling networks between specific antenna pairs (first and second antennas, third and fourth antennas), the system maintains four antennas for high data rate transmission while ensuring that each antenna operates with minimal correlation to others, thereby preserving MIMO system performance.
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 effectively enhances antenna isolation, ensuring higher efficiency and reduced coupling between antennas, particularly for low-frequency bands, thereby meeting the requirements of 4×4 MIMO systems and supporting miniaturization of terminal antennas.
Implementation Method 1
an electromagnetic coupling module configured to block coupling signal transmission between two neighboring antennas
Data Source
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Figure 3
Figure 4(a)~4(b)
AI summary
The present invention discloses an antenna unit and a terminal. The antenna unit disclosed by the present invention includes an antenna circuit board, at least two neighboring antennas and an electromagnetic coupling module used for isolating coupling signal transmission between two neighboring antennas, wherein the electromagnetic coupling module is connected in series between the two neighboring antennas. The present invention uses the electromagnetic coupling module to isolate signal transmission between the two neighboring antennas, i.e., electric signals in the two antennas are unable to be transmitted to opposite end, thereby reducing signal coupling between the neighboring antennas and improving the isolation between the two neighboring antennas.