Protruded Ground Plane Antenna Isolation
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Solution Overview
Problem
Existing dual-antenna systems in mobile devices face challenges in maintaining high isolation and reducing mutual coupling and interference, particularly in WWAN high bands like GSM1800/1900, due to excited surface currents on the ground plane.
Innovation Solution
A communication device design featuring a first antenna and a second antenna with a protruded ground plane forming an L-shape, where the second antenna is a slot antenna with an open end not adjacent to the first antenna, achieving isolation of lower than -16dB in the GSM1800/1900 band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple antennas are disposed at one end of the mobile device to increase data transmission, then bandwidth and SAR requirements can be met, but mutual coupling and interference between antennas increase due to excited surface currents on the ground plane
Solution Approach 1:
The ground plane is segmented into a main ground plane and a protruded ground plane that extends toward the other end of the mobile device. This segmentation divides the continuous ground plane into distinct regions, allowing the protruded ground plane to serve as an isolation structure that reduces surface current coupling between antennas while maintaining the electrical connectivity needed for antenna operation.
Solution Approach 2:
The protruded ground plane acts as an intermediary structure between the first and second antennas. It serves as a mediator that controls and directs surface currents, preventing them from coupling between the antennas. The protruded ground plane with its specific geometry (extending toward the other end of the device) functions as an active element in managing electromagnetic interactions.
2Volume of moving object
If antennas are placed in a limited space of the mobile device, then device compactness is achieved, but maintaining high isolation between antennas becomes difficult
Solution Approach 1:
The ground plane structure is extended into a third dimension by creating a protruded ground plane that extends toward the other end of the mobile device. This dimensional change allows the system to achieve better antenna isolation without increasing the planar footprint, effectively utilizing the available Z-direction space to improve electromagnetic performance.
Solution Approach 2:
The protruded ground plane creates an asymmetric ground plane structure that is not uniformly distributed under both antennas. This asymmetric configuration is strategically designed to control surface current paths, creating different electromagnetic environments for each antenna that reduces mutual coupling while maintaining compact dimensions.
Data Source
Figure 1A~1B
Figure 2~3
Figure 4~5
AI summary
The present invention is related to a communication device which includes a ground element and an antenna system. The ground element includes a main ground plane and a protruded ground plane. The antenna system includes a first antenna and a second antenna. The first antenna includes a metal radiation element and is adjacent to the main ground plane of the ground element. The second antenna is a slot antenna and is formed in the protruded ground plane of the ground element. The protruded ground plane is adjacent to the first antenna.