Low PIM Antenna With Isolation Rings for MIMO Systems
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Solution Overview
Problem
Current antenna solutions for wireless communication networks face challenges in achieving low passive intermodulation (PIM) performance, especially in achieving a peak PIM level lower than −155 dBc, and maintaining isolation between operating bands without distorting the radiation pattern, particularly in distributed antenna systems (DAS) and MIMO configurations.
Innovation Solution
The implementation of a low PIM antenna apparatus featuring a pair of radiating elements, a conductive ground plane, and one or more isolation rings electrically coupled to the ground plane, along with a radome, which reduces PIM levels and improves isolation between radiating elements while maintaining an omni-directional radiation pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current DAS antenna solutions are used, then antenna size is reduced, but peak PIM performance cannot achieve lower than −155 dBc and isolation between antennas is insufficient
Solution Approach 1:
An isolation ring is introduced as an intermediary component between two radiating elements. The isolation ring is electrically connected to the ground plane and physically positioned between the radiating elements to provide electromagnetic isolation. This mediator structure enables both radiating elements to be closely spaced while achieving the required isolation performance and low PIM characteristics without increasing overall device complexity
Solution Approach 2:
The ground plane is segmented into multiple regions including a first ground region connected to the first radiating element, a second ground region connected to the second radiating element, and a third ground region between them. The isolation ring is connected to this segmented ground structure, creating distinct electromagnetic zones that reduce interference while maintaining compact dimensions
2Reliability
If ground plane is extended between adjacently disposed MIMO antennas to improve isolation, then isolation between operating bands improves, but radiation antenna pattern is distorted
Solution Approach 1:
The isolation ring serves as a targeted intermediary that provides electromagnetic isolation between radiating elements without extending the ground plane between them. By placing the isolation ring specifically between the radiating elements and connecting it to the ground plane at controlled points, the patent achieves band isolation while preserving the omnidirectional radiation pattern, avoiding the distortion caused by extended ground planes
3Productivity
If multiple radiating elements are closely located for MIMO configuration, then system capability is enhanced, but isolation between elements is insufficient leading to increased bit error rate
Solution Approach 1:
The isolation ring is positioned between closely located radiating elements in MIMO configuration, providing the necessary electromagnetic isolation to reduce bit error rate. This allows multiple radiating elements to be closely spaced for enhanced system capability while maintaining adequate isolation through the intermediary ring structure connected to the ground plane
Data Source
AI summary
Low passive intermodulation (PIM) antenna assemblies and methods for utilizing the same. In one embodiment, the low PIM antenna assemblies described herein offer the lowest PIM level for the DAS antenna as compared with current PIM solutions currently available in the market place as well as the improvement of isolation between the radiating elements using inserted isolation rings as well as a more omni-directional radiation pattern using the insertion of slots into the radiating elements themselves. Methods of manufacturing and using the aforementioned low PIM antenna assembly are also disclosed.