Soft Contacting Rotational Interface for Concurrent RF and Optical Signal Transmission
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Solution Overview
Problem
Current RF rotary joints and fiber optic rotary couplers face challenges in efficiently transferring RF and optical signals across rotating interfaces, particularly in terms of size, weight, torque, wear, and alignment, with existing solutions either requiring large chokes or being prone to wear and alignment issues.
Innovation Solution
A system utilizing soft contacting rotational interfaces with conductive fiber brush bundles and coaxial conductors, featuring tapered round heads and insulating assemblies, allows for concurrent transmission of RF and optical signals across rotating interfaces, minimizing size and maintaining reliable contact without the need for precise alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-contacting interface with λ/4 chokes is used, then physical wear is eliminated, but size and weight increase significantly
Solution Approach 1:
The patent replaces the mechanical contact system (sliding contacts) with an electromagnetic field-based system (λ/4 chokes creating standing waves). The RF energy is transmitted through the air gap via electromagnetic resonance rather than physical contact, eliminating wear while avoiding the weight penalty of traditional mechanical slip rings by using a different physical principle entirely.
Solution Approach 2:
The patent changes the operating parameters by using λ/4 chokes tuned to specific frequencies to create resonant standing waves. By adjusting the choke length and impedance to match quarter-wavelength conditions at the operating frequency, the system achieves efficient energy transfer through the air gap without requiring heavy mechanical components.
2Volume of moving object
If contacting rotating interface is used, then size is reduced, but torque increases and wear occurs
Solution Approach 1:
The patent eliminates the mechanical contact interface entirely by using electromagnetic field coupling through air gaps. This substitution removes the friction and torque issues inherent in contacting interfaces while maintaining a compact size, as the electromagnetic field requires no physical contact surfaces or heavy sliding components.
3Volume of moving object
If contacting rotating interface is used, then size is reduced, but alignment precision requirements increase
Solution Approach 1:
By replacing the mechanical contact system with electromagnetic field coupling, the patent eliminates the need for precise concentric alignment of rotating and stationary components. The electromagnetic field can couple effectively through the air gap without requiring tight tolerances, significantly reducing manufacturing precision requirements while maintaining compact dimensions.
4Adaptability or versatility
If conventional fiber optic rotary coupler is used, then optical signal transmission is achieved, but RF signal transmission is not possible
Solution Approach 1:
The patent merges the RF rotary joint and fiber optic rotary coupler into a single integrated assembly. The same rotating shaft and air gap structure that enables RF transmission via λ/4 chokes also accommodates the optical fiber alignment mechanism, allowing both RF and optical signals to be transmitted simultaneously through one unified interface rather than requiring separate systems.
Solution Approach 2:
The rotating shaft assembly is designed to perform multiple functions: it supports both the RF transmission system (with λ/4 chokes and air gap) and the optical fiber transmission system (with alignment ferrules). This multi-functional design allows a single component to handle both electromagnetic and optical signal transmission, increasing versatility without proportionally increasing component quantity.
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 system achieves a compact, low-profile design with reduced insertion loss and increased reliability, capable of operating in harsh environments and maintaining signal integrity under conditions like temperature change, vibration, and shock.
Implementation Method 1
a plurality of conductive fiber brush bundles (12, 22) to form soft contacting rotational interfaces around rotating and stationary conductors of a coaxial line
Implementation Method 2
a fiber optical wire (38) to transfer optical signals from the rotating to the stationary object
Implementation Method 3
said fiber brush bundle has two end portions, one of said end portion being coaxially and electrically fixed with said stationary shield conductor, while a contacting end of said first stationary RF connector assembly is electrically engage with an outside surface of an end portion of said stationary core conductor
Data Source
AI summary
A system of soft contacting rotational interfaces with long service life, maintenance free, and high reliability, comprises a RF rotary joint and a single channel fiber optic rotary coupler and more particularly, a system having a plurality of conductive fiber brush bundles, a fiber optical wire and a coaxial conductor for transferring RF and optical signal(s) concurrently between relatively rotatable objects.