Non-Metallic Base Station Antenna Cage for Low-PIM Transmission
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Solution Overview
Problem
Conventional base station antennas face challenges with passive intermodulation distortion (PIM) due to metal frame structures, which can hinder the transmission of high-frequency electromagnetic waves and affect antenna performance, especially in multi-band and 5G communication systems.
Innovation Solution
A non-metallic, lightweight structural cage with laterally and longitudinally extending struts is used within the base station antenna housing, coupled with a frequency selective surface (FSS) and matching layers to reduce PIM and enhance wave transmission across different frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metal frame structure is used in the base station antenna, then structural strength and rigidity are improved, but passive intermodulation distortion (PIM) increases and high-frequency electromagnetic wave transmission is hindered
Solution Approach 1:
The patent removes the metal frame structure from the antenna housing and replaces it with a non-metallic cage structure. This extraction of the harmful metal component eliminates the source of passive intermodulation distortion while maintaining the necessary structural support through the non-metallic cage framework.
Solution Approach 2:
The patent employs composite material construction by combining non-metallic cage structures with strategic metal components only where absolutely necessary for structural integrity. The housing integrates non-metallic materials (such as plastic or composite polymers) for the main body, eliminating PIM-generating metal surfaces while using metal only in isolated, controlled locations if needed for mechanical strength.
2Object-generated harmful factors
If a non-metallic cage structure is used, then passive intermodulation distortion is reduced and electromagnetic wave transmission is improved, but structural strength may be compromised
Solution Approach 1:
The patent uses composite material construction by combining non-metallic cage structures with strategic metal components only where absolutely necessary for structural integrity. The housing integrates non-metallic materials (such as plastic or composite polymers) for the main body, eliminating PIM-generating metal surfaces while using metal only in isolated, controlled locations if needed for mechanical strength.
Solution Approach 2:
The cage structure employs curved and optimized geometric designs to distribute mechanical stresses efficiently throughout the non-metallic framework. The struts are configured with optimized angles and curves that enhance structural rigidity without requiring metal materials, allowing the non-metallic cage to withstand operational forces while maintaining low PIM characteristics.
3Ease of manufacture
If conventional metal structures are used, then manufacturing simplicity is maintained, but PIM reduction and high-frequency wave transmission enhancement are limited
Solution Approach 1:
The patent removes the metal frame structure from the antenna housing and replaces it with a non-metallic cage structure. This extraction of the harmful metal component eliminates the source of passive intermodulation distortion while maintaining the necessary structural support through the non-metallic cage framework.
Solution Approach 2:
The patent employs a cage structure made from non-metallic materials that can be manufactured as integrated housings or modular components. The cage struts can be formed through injection molding or extrusion processes, allowing for relatively straightforward manufacturing of the non-metallic structure that eliminates PIM while providing adequate structural support.
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
The solution effectively reduces PIM and improves the transmission of high-frequency electromagnetic waves, enhancing the performance and capacity of base station antennas without increasing the number of antennas, particularly in multi-band and 5G applications.
Implementation Method 1
The FSS can be configured to reflect electromagnetic waves within a first operational frequency band. The FSS can be further configured such that electromagnetic waves within a second operational frequency band can propagate through the FSS.
Implementation Method 2
The cage may inhibit or reduce passive intermodulation distortion (PIM) that may otherwise arise using metal frame structures. The solution effectively reduces PIM and improves the transmission of high-frequency electromagnetic waves
Data Source
AI summary
Base station antennas include a base station antenna housing with an internal cage defining a monolithic structure with front and rearward sets of longitudinally extending and laterally extending struts providing a light-weight, non-metallic body with radiating elements positioned inside the cage. The cage can attach to a primary reflector and can hold first and second matching layers and a reflector.