Low-PIM Universal Antenna Mount with Pressure Bushing
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Solution Overview
Problem
Passive intermodulation (PIM) interference in cellular telephone base station antenna sites is exacerbated by loose metal-to-metal connections, which generate non-linear junctions and reduce signal quality, even when located outside the main beam of the antenna.
Innovation Solution
The implementation of low-PIM universal equipment mounts with pressure bushings that provide electrical isolation and stable structural support, using polymeric or metal materials to prevent physical movement and reduce PIM generation, even when subjected to mechanical loads and environmental factors like ice and wind.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional metal brackets and mounting hardware are used to support ancillary equipment, then structural support and equipment mounting capability are provided, but loose metal-to-metal connections are created that generate PIM interference
Solution Approach 1:
The patent introduces non-conductive mounting brackets made of composite materials (fiberglass-reinforced plastic) as intermediaries between metal equipment and the metal mounting pole. These brackets mechanically connect equipment to the pole while electrically isolating metal components, thereby preventing loose metal-to-metal connections that generate PIM interference while maintaining structural support capability.
Solution Approach 2:
The patent changes the material parameter of mounting brackets from conductive metal to non-conductive composite materials. This material parameter change eliminates the electrical conductivity that causes PIM interference while preserving the mechanical strength needed for structural support through fiberglass reinforcement.
2Adaptability or versatility
If large brackets with threaded rods and multiple interface brackets are used to accommodate various pipe diameters, then adaptability to different mounting configurations is achieved, but device complexity and weight increase
Solution Approach 1:
The patent designs universal mounting brackets with adjustable features that can accommodate multiple pipe diameters (2 inches to 6 inches) without requiring different bracket sizes or additional interface brackets. The brackets incorporate adjustable threaded rods and modular components that can be configured for various mounting scenarios, eliminating the need for multiple specialized brackets.
Solution Approach 2:
The patent removes unnecessary intermediate interface brackets from traditional mounting assemblies by designing integrated universal brackets that directly mount equipment to the pole. This extraction of redundant components simplifies the overall mounting structure while maintaining adaptability through adjustable features.
3Strength
If high clamping force is applied to secure brackets to the mounting pole, then secure mechanical attachment is achieved, but the galvanized coating on the pole is broken creating exposed steel that corrodes over time
Solution Approach 1:
The non-conductive composite brackets act as intermediaries that distribute clamping forces over a larger surface area and prevent direct metal-to-metal contact between mounting hardware and the pole. This intermediary layer protects the galvanized coating from breaking while maintaining secure mechanical attachment through enhanced friction and distributed loading.
Solution Approach 2:
The patent uses fiberglass-reinforced plastic composite materials for mounting brackets that provide both mechanical strength for secure attachment and electrical non-conductivity to protect the pole coating. The composite material's inherent flexibility and friction characteristics enhance attachment security without requiring excessive clamping force that would damage the galvanized coating.
Data Source
AI summary
The present invention meets the needs described above through low-PIM universal antenna equipment mounts and associated assemblies for use at cell sites. The universal mounts are typically deployed in antenna equipment assemblies located in the nearfield reactive region behind the base station antennas. The mounts suppress PIM generation as compared to conventional equipment mounts even though the universal mounts are located well outside the main beam of the base station antenna. An illustrative universal mount includes a pressure bushing with a cap that includes a pair of parallel rails to stabilize the bushing on a metal mast. The rails allow the pressure bushing to transfer the load of the supported equipment to the curved surface of round cylindrical masts irrespective of the pipe diameter within the typical range of mast diameters, such as 2 inches to 6 inches in diameter.