Multi-Antenna Structure Low-Frequency Isolation
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Solution Overview
Problem
Conventional MIMO antennas in mobile devices suffer from poor low-frequency isolation and correlation due to omnidirectional radiation, leading to limited improvement in transmission rate.
Innovation Solution
The multi-antenna structure includes two metal lines on the short sides of the grounded metal surface, equalizing the current path length with the long sides, thereby reducing interference between antennas and enhancing low-frequency isolation by ensuring equal longitudinal and transverse currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If two antennas are arranged on the short sides of the grounded metal surface in a conventional MIMO structure, then the device can achieve multi-antenna functionality, but the low frequency isolation between antennas deteriorates due to unequal current paths
Solution Approach 1:
The patent introduces asymmetric metal lines (first and second metal lines) with different configurations on the short sides of the grounded metal surface. These metal lines have different lengths and positions, creating asymmetric current paths that compensate for the inherent symmetry of the short sides, thereby equalizing the total current path lengths and improving low frequency isolation between antennas
Solution Approach 2:
The patent modifies the current path parameters by adding metal lines with specific lengths and positions. The first metal line has a first length and the second metal line has a second length, where these parameters are carefully designed to make the total current path lengths equal. This parameter adjustment directly addresses the low frequency isolation issue by changing the electrical characteristics of the antenna structure
2Device complexity
If the current path of the short sides is kept short in a conventional antenna structure, then the device complexity is reduced, but the longitudinal current becomes larger than transverse current, causing poor isolation
Solution Approach 1:
The patent extends the current path from a simple two-dimensional path along the short sides to a three-dimensional path by adding metal lines that extend in different directions and planes. The first metal line and second metal line create additional current path dimensions, allowing the current to travel longer distances while maintaining a planar structure, thus equalizing longitudinal and transverse currents without significantly increasing overall device complexity
Data Source
AI summary
A multi-antenna structure includes a base plate, a first antenna, a second antenna, a first metal line, and a second metal line. The base plate includes a grounded metal surface. The grounded metal surface includes two short sides and two long sides. The first antenna and the second antenna are arranged on the base plate. The first metal line and the second metal line are electrically connected to the two short sides of the grounded metal surface. A current path of the two short sides is prolonged because of the first metal line and the second metal line. A longitudinal current is equal to a transverse current at a low frequency. A current of the first antenna and a current of the second antenna does not interfere each other. Isolation between the first antenna and the second antenna is improved.