Antenna Positioner Guide Ring With Kapton Shims
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Solution Overview
Problem
Existing antenna positioners for satellite communications face issues with singular points, weight, thermal expansion, and galvanic coupling, leading to performance degradation and reliability concerns, particularly in temperature variations and dynamic conditions.
Innovation Solution
A positioner design using an aluminum first ring and stainless steel second ring with a guide ring structure that incorporates Kapton shims for sliding and differential expansion management, along with a serrated part for mass and stiffness, and a ball recirculation system for precision, eliminating singular points and reducing weight while maintaining stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stainless steel and aluminum are combined in the positioner structure, then corrosion resistance is improved, but thermal expansion differences cause rounding of curved guides and variation in gear backlash
Solution Approach 1:
The positioner structure is divided into separate aluminum and stainless steel components that are selectively assembled. The aluminum guide ring and stainless steel support structure are connected through precision-machined interfaces with adjustable shims, allowing each material to perform its optimal function while maintaining overall dimensional stability through controlled assembly rather than monolithic construction.
Solution Approach 2:
The invention controls the thermal expansion parameters by using precision-machined interfaces with specific tolerances and adjustable shims. The assembly parameters are designed to accommodate differential thermal expansion within acceptable ranges, maintaining guide roundness and gear backlash within specified limits across the operating temperature range of -40°C to +80°C.
2Weight of moving object
If aluminum is used for the guide ring, then weight is reduced, but galvanic coupling with stainless steel components causes corrosion
Solution Approach 1:
Electrical insulation elements are introduced as intermediaries between the aluminum guide ring and stainless steel components. These insulation elements prevent direct galvanic contact while allowing mechanical connection, thus eliminating the galvanic couple pathway while maintaining the lightweight aluminum structure.
Solution Approach 2:
Different materials are applied locally where needed: aluminum is used for the guide ring where weight reduction is critical, while stainless steel is used for the support structure where strength and corrosion resistance are priorities. Electrical insulation is applied locally at the interfaces between dissimilar metals to prevent galvanic coupling only where necessary.
3Reliability
If heavy and complex structures are used for three-axis positioners without singular points, then singularity problems are solved, but weight and device complexity increase
Solution Approach 1:
Instead of adding complex mechanical structures to eliminate the singular point, the invention inverts the approach by using a two-axis positioner with a specially designed guide ring geometry and control system that avoids the singular point through software-based trajectory planning and control algorithms, maintaining mechanical simplicity while achieving the same operational reliability.
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 provides a lightweight, high-performance antenna positioner with no singular points, improved thermal stability, and resistance to corrosion, ensuring precise pointing capabilities over a wide temperature range.
Implementation Method 1
The use of steel with aluminum also generates a variation in the backlash of the gear depending on the temperature. The shape of the first orifices of a crown is for example identical to the shape of the second orifices of the crown. The fixing means are, for example, screws and a lock nut system making it possible to fix all the elements constituting the crown before its mounting on the positioner.
Implementation Method 2
A positioner design using an aluminum first ring and stainless steel second ring with a guide ring structure that incorporates Kapton shims for sliding and differential expansion management
Implementation Method 3
The guide ring comprises, for example, two second rings arranged on either side of said first ring, a second ring supporting one or more rails comprising ball recirculation tracks
Implementation Method 4
a second ring supporting one or more rails comprising ball recirculation tracks
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
Antenna positioner comprising at least the following elements: A base intended to receive a support cradle mounted rotatably relative to the base along a first axis of rotation, said support cradle comprising at least one guide ring (21) composed of at least the following elements: • a first ring (210) made of a first material, • a shim (211) interposed between the first ring and a second ring (212) made of a second material, the shape of the shim (211) being adapted to the shape of the first ring and to the shape of the second ring, • said shim being formed of a material adapted to promote the sliding of the first ring relative to the second ring and to avoid chemical deterioration phenomena, • the first ring, the second ring and the shim having openings allowing the passage of fastening means and a pivot connection.