Dielectric Bushing Isolates Fastener to Mitigate Passive Intermodulation
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Solution Overview
Problem
Passive-intermodulation caused by mechanical components in utility or communications systems introduces interference into electromagnetic signals, degrading communication performance.
Innovation Solution
A passive-intermodulation-mitigating mounting assembly that includes a first and second bracket with through holes, and a dielectric bushing to physically and electrically isolate fasteners from the brackets, reducing non-linearities and interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If mechanical components (brackets, fasteners) are mated together to form a mounting assembly, then structural strength and stability are improved, but passive-intermodulation occurs causing signal interference and degraded communication performance
Solution Approach 1:
A dielectric bushing is introduced as an intermediary component between the fastener and the bracket. The bushing has a fastener-receiving portion that receives the fastener and a bracket-engaging portion that engages the bracket, creating physical and electrical isolation. This intermediary structure prevents direct electrical contact between metal components while maintaining mechanical attachment, thereby eliminating passive-intermodulation interference.
Solution Approach 2:
The bushing is constructed from composite materials comprising a dielectric material (such as plastic or polymer) that provides electrical isolation properties. This composite material structure allows the bushing to simultaneously provide mechanical support, electrical insulation, and structural integrity, resolving the contradiction between structural strength and interference prevention.
2Ease of manufacture
If metal fasteners directly contact metal brackets, then ease of manufacture and assembly are improved, but non-linearities are introduced causing signal degradation
Solution Approach 1:
The dielectric bushing serves as a mediator between the metal fastener and metal bracket, maintaining ease of assembly through simple insertion and engagement while preventing harmful direct metal-to-metal contact. The bushing's design allows for straightforward assembly procedures without requiring complex manufacturing processes.
Solution Approach 2:
The electrical conductivity parameter of the mounting assembly is changed by introducing the dielectric bushing. The bushing transforms the electrical contact path from conductive (metal-to-metal) to insulating (metal-to-dielectric), thereby changing the electrical parameters of the assembly to eliminate non-linearities while maintaining mechanical functionality.
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 isolation provided by the bushing inhibits passive-intermodulation, improving communication performance by reducing electrical conduction between mechanical components.
Implementation Method 1
The bushing can include a dielectric material configured for insertion into the first through hole or the second through hole to physically and electrically isolate the fastener from the first bracket or the second bracket
Data Source
AI summary
A passive-intermodulation-mitigating mounting assembly for a fixture, such as can be affixed to a utility or communications monopole can include a first bracket and a second bracket respectively defining a first through hole and a second through hole. In some examples, a mounting plate supports an antenna or a radio. A fastener can extend through the first through hole and the second through hole, for instance to couple the first bracket with the second bracket to attach the mounting assembly to a fixture. The passive-intermodulation-mitigating mounting assembly can include a bushing that can be inserted into a through hole, and the bushing can physically and electrically isolate the fastener from one or more of the brackets. The isolation of the bushing helps inhibit the passive-intermodulation of the mounting assembly when the fastener extends, via the first bushing, through at least one of the through holes.