Omni-Directional MIMO Antenna Structure for Compact High Isolation
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Solution Overview
Problem
MIMO antennas in distributed antenna systems face challenges in achieving high isolation between radiating elements while maintaining a compact and thin design to cover a wide frequency range and ensure omni-directional radiation, especially in indoor communication environments with high traffic capacity and communication shadow areas.
Innovation Solution
The design incorporates a board with spaced first and second feed lines, ground patterns, a parasitic patch, and projections to enhance isolation, using a connection element of λ/2 length and stubs for electromagnetic coupling, along with a parasitic patch that overlaps ground patterns and protrudes to position feed points between projections, ensuring effective radiation and isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If multiple radiating elements are mounted close together in a compact antenna design, then the antenna size is reduced, but the isolation between radiating elements deteriorates
Solution Approach 1:
The patent introduces a parasitic patch on the rear surface of the board, creating a three-dimensional structure that extends beyond the traditional planar configuration. This additional dimension allows the feed lines to be routed through via holes from the front surface to the rear surface, enabling the radiating elements to be positioned closer together while maintaining isolation through the spatial separation provided by the parasitic patch structure.
Solution Approach 2:
The parasitic patch acts as an intermediary element between the radiating elements and the ground pattern. It mediates the electromagnetic interaction between closely spaced radiating elements by providing an additional coupling path through the via holes and connection elements, thereby maintaining isolation performance despite the reduced distance between radiators.
2Device complexity
If feed lines are routed on the front surface of the board, then the structure is simplified, but the isolation between adjacent feed lines deteriorates
Solution Approach 1:
The patent transitions the feed line routing from a two-dimensional planar path on the front surface to a three-dimensional path that extends through via holes to the rear surface of the board. This vertical transition into the third dimension allows the feed lines to be closely spaced on the front surface while maintaining isolation through the spatial separation achieved in the vertical dimension and on the rear surface.
3Volume of moving object
If the antenna is designed to be thin and compact for indoor installation, then the installation flexibility is improved, but the radiation performance and isolation characteristics deteriorate
Solution Approach 1:
The patent utilizes the thickness dimension of the board by routing feed lines through via holes to the rear surface and introducing a parasitic patch structure. This approach effectively uses the available vertical space to achieve isolation and radiation performance without increasing the overall footprint or requiring a thicker board, thereby maintaining installation flexibility while improving 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
This configuration secures high isolation between radiators while minimizing shadow areas through omni-directional radiation, effectively addressing the need for compact, high-performance MIMO antennas in indoor communication systems.
Implementation Method 1
a parasitic patch formed on a rear surface of the board; and first and second projections protruding from the parasitic patch in a direction of the first feed point and the second feed point
Implementation Method 2
a first ground pattern that surrounds the first feed line, is electrically connected to a ground, and extends in a longitudinal direction of the board
Data Source
AI summary
An omni-directional MIMO antenna comprises: a board; a first feed line and a second feed line formed on the board and spaced apart from each other; a first radiator receiving a feed signal from the first feed line; a second radiator receiving a feed signal from the second feed line; a first ground pattern that surrounds the first feed line, is electrically connected to a ground, and extends in a longitudinal direction of the board; a second ground pattern that surrounds the second feed line, is electrically connected to a ground, and extends in a longitudinal direction of the board; a parasitic patch formed on a rear surface of the board; a first feed point formed on the rear surface and providing a feed signal to the first feed line and a second feed point formed on the rear surface and providing a feed signal to the second feed line.