MIMO Antenna Dipole Axis Orientation for Low Correlation
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Solution Overview
Problem
MIMO antennas in small-sized radio devices face high correlation between partial antennas due to their close proximity, which degrades efficiency, especially in the lower operating band, and is exacerbated by user interactions.
Innovation Solution
The MIMO antenna design features two antenna components with substrates and radiators positioned on opposite sides of the circuit board, where the 'dipole axes' of the partial antennas have clearly different directions, and the ground plane is arranged to minimize correlation between the signals, achieving low correlation even at frequencies below 1 GHz.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If multiple antenna components are placed close together in a small-sized radio device, then the device size is reduced, but the correlation between antenna signals increases
Solution Approach 1:
The patent positions antenna components on opposite sides of the circuit board (different spatial dimensions) rather than placing them close together on the same side. This three-dimensional arrangement reduces electromagnetic coupling and signal correlation while maintaining a compact overall device footprint, directly resolving the contradiction between small device size and low signal correlation.
Solution Approach 2:
The patent employs asymmetric ground plane arrangements where different antenna components have ground planes of different sizes and positions. This asymmetry creates different current distribution patterns and radiation characteristics for each antenna, reducing mutual coupling and signal correlation even when antennas are in close proximity, thus enabling compact device design without sacrificing MIMO performance.
2Ease of manufacture
If antenna components are positioned close together to reduce device size, then manufacturing cost is reduced, but efficiency in lower operating band degrades
Solution Approach 1:
The patent applies different ground plane configurations to different antenna components based on their specific operating requirements. Each antenna component has its ground plane optimized locally with respect to size, shape, and position, allowing efficient operation in lower frequency bands while maintaining compact overall dimensions. This localized optimization enables cost-effective manufacturing without compromising antenna efficiency.
3Reliability
If ground plane size is increased to improve antenna performance, then signal correlation decreases, but device volume increases
Solution Approach 1:
The patent utilizes the third dimension by placing antenna components on opposite sides of the circuit board with strategically positioned ground planes. This vertical separation in the z-dimension reduces the need for large lateral ground plane areas, achieving low signal correlation without significantly increasing the device's footprint or overall volume, thus resolving the contradiction between correlation reduction and volume constraints.
Data Source
AI summary
An antenna structure that provides spatial multiplexing capabilities. In one embodiment, the antenna comprises two antenna components with a substrate and radiator, the components being located on opposite sides of the circuit board of a radio device. Each antenna component operates in combination with the ground plane of the radio device to form a partial antenna, the operating band of which is below the frequency of 1 GHz. The ground plane and the feed points of the partial antennas are arranged so that the ‘dipole axes’ of the partial antennas have clearly different directions at the frequencies of said operating band.