RF Rotary Joint Curved Sliding Waveguides
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Solution Overview
Problem
Current RF rotary joints face challenges in reducing size, increasing the number of RF transmission paths, and maintaining RF performance with large angular deflection and compactness, especially in Ka band transmission and reception for satellites, due to limitations in bandwidth and mechanical complexity.
Innovation Solution
The RF rotary joint employs meta-materials with periodic studs to confine waves, using a curved sliding waveguide design that deflects along the electric field plane, allowing for a more compact structure with multiple RF paths without contact, and meta-material pads for guidance, enabling efficient transmission across a wide range of frequencies and angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a conventional RF rotary joint structure is used, then the device can transmit RF electromagnetic waves, but the device size becomes large and the number of RF transmission paths is limited
Solution Approach 1:
The RF rotary joint is divided into multiple independent curved sliding waveguides (first, second, third waveguides) that can be angularly distributed around the rotation axis. Each waveguide functions as an independent RF transmission path, allowing multiple simultaneous RF channels without increasing the overall device volume significantly
Solution Approach 2:
The patent transitions from planar RF transmission surfaces to three-dimensional curved sliding waveguides that wrap around the rotation axis. This spatial arrangement allows multiple RF paths to be packed more efficiently in the radial and axial directions, increasing the number of transmission paths while maintaining a compact cylindrical form factor
2Quantity of substance
If the number of RF transmission paths is increased, then more RF channels are available, but the device complexity increases
Solution Approach 1:
The curved sliding waveguide structure serves multiple functions simultaneously: it guides RF electromagnetic waves, provides mechanical support, enables rotational movement, and maintains RF isolation between adjacent paths. This multi-functionality reduces the need for additional components and simplifies the overall device architecture
Solution Approach 2:
Multiple RF transmission functions are merged into a single integrated rotary joint assembly. The waveguides share common structural elements such as the rotation axis, mounting flanges, and sealing mechanisms, allowing multiple RF channels to be implemented without proportionally increasing mechanical complexity
3Volume of moving object
If a compact structure is used, then the device size is reduced, but maintaining RF performance with large angular deflection becomes difficult
Solution Approach 1:
The patent employs curved sliding waveguides with optimized radii of curvature that allow the RF transmission paths to accommodate large angular deflections (±55 degrees) while maintaining proper waveguide geometry. The curved design naturally follows the rotational arc, preserving RF performance across the full rotation range within a compact form factor
4Reliability
If contactless transmission is used, then mechanical wear is reduced, but confining and guiding RF electromagnetic signals becomes more challenging
Solution Approach 1:
The patent replaces traditional mechanical contact interfaces (such as sliding contacts or brushes) with contactless curved sliding waveguide interfaces. RF electromagnetic signals are transmitted through the curved waveguide structures without physical contact between rotating and stationary parts, eliminating mechanical wear while maintaining signal integrity through properly designed waveguide boundaries
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
This configuration results in a compact, high-performance RF rotary joint that supports multiple RF paths with minimal size increase, maintaining RF integrity and allowing for efficient transmission across a broad frequency range and large angular deflections, such as ±55 degrees, while reducing mechanical complexity and cost.
Implementation Method 1
The first internal electromagnetic signal transmission surface comprises a succession of a predetermined number NC of first sections of surfaces of revolution around the axis (Z), located at first different levels L1(k), k varying from 1 to NC, along the longitudinal axis of symmetry (Z) around first internal mean ray(s) r1(k) associated, k varying from 1 to NC, and comprising N first RF access port(s) and first means, based on meta-materials, for confining and guiding RF electromagnetic signals
Implementation Method 2
each RF transmission path Vi, i varying from 1 to N, comprises a first different RF curved sliding waveguide
Data Source
Figure 1A~1B
Figure 2A~2C
Figure 3~5
AI summary
A rotary RF joint about an axis of rotation (Z) has a number N, greater than or equal to 1, of RF transmission channels, a first internal surface of revolutional symmetry about the axis (Z) and of RF transmission having a first internal radius r1, and a second external surface of revolutional symmetry about the axis (Z) and of RF transmission having a second external radius r2, strictly less than said first internal radius r1.The first and second RF transmission surfaces facing each other and rotating about the axis (Z) are configured through the first and second radii r1, r2, the geometry of the first and second RF accesses, and the geometry of the first and second RF containment and guidance means, such that: - each RF transmission channel Vi, i varying from 1 to N, has a first rotating RF waveguide, and - the first N rotating RF waveguides are distributed angularly over a predetermined number NC, greater than or equal to 1 and less than or equal to N, of segments of surfaces of revolution about the axis (Z) of the second RF transmission surface, each of the NC segment(s) being located along the longitudinal axis of symmetry (Z) at a different predetermined level L1(k).