Hybrid RF Autotracking for Spacecraft Antenna Pointing
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Solution Overview
Problem
Existing RF autotracking systems for spacecraft antennas are inadequate in compensating for high-frequency pointing disturbances, such as those caused by eclipse-induced thermal transients and thruster startup, as they rely on mechanical actuators that are limited by inertia, leading to incomplete correction of pointing errors.
Innovation Solution
The implementation of a hybrid RF autotracking system that combines a closed-loop mechanically actuated antenna pointing mechanism with an open-loop electronic beam forming network using variable amplitude and phase (VAP) adjusting arrangements, allowing for electronic adjustment of beam forming coefficients to correct high-frequency pointing errors beyond the capability of mechanical actuators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If mechanical actuators are used for antenna pointing adjustment, then the system structure is simple and reliable, but the response speed is limited by inertia and cannot correct high-frequency pointing disturbances
Solution Approach 1:
The patent replaces the purely mechanical actuator system with a hybrid system that incorporates an electronic phased array feed system. The electronic beam forming capability allows for rapid adjustment of beam pointing without the inertia limitations of mechanical actuators, achieving high-frequency correction through electronic means rather than mechanical movement.
Solution Approach 2:
The patent introduces a dual-mode control system where the mechanical actuator handles low-frequency, coarse positioning while the electronic phased array handles high-frequency, fine adjustments. This dynamic division of labor allows the system to respond to pointing disturbances across a broader frequency spectrum, with the electronic component providing rapid response capability.
2Measurement precision
If electronic beam forming with VAP adjusting arrangements is used, then high-frequency pointing errors can be corrected rapidly, but the device complexity increases
Solution Approach 1:
The patent integrates the VAP adjusting arrangements into the existing beam forming network, allowing the same electronic hardware to serve multiple functions: normal beam forming operations and pointing error correction. The VAP arrangements adjust both amplitude and phase of feed elements, enabling the system to perform both routine beam shaping and dynamic pointing compensation using the same infrastructure.
3Reliability
If purely mechanical antenna pointing control is used, then the system is simpler to implement, but it cannot adequately compensate for high-frequency disturbances such as eclipse-induced thermal transients and thruster startup
Solution Approach 1:
The patent implements a feedback mechanism where the performance of the antenna system is continuously monitored and used to adjust the VAP settings in real-time. This closed-loop control allows the electronic beam forming system to detect and correct pointing errors caused by high-frequency disturbances, automatically adapting to maintain beam stability without requiring manual intervention or system redesign.
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 hybrid approach effectively compensates for high-frequency pointing disturbances, providing precise and rapid correction of antenna pointing errors, improving the stability and accuracy of user beams even under conditions that would otherwise cause dithering or unstable operation.
Implementation Method 1
a plurality of radiating feed elements configured as a phased array configured to produce, in a far field of the reflector, a set of contiguous abutting user beams
Implementation Method 2
a beam forming network (BFN) disposed proximate to the phased array, the BFN including a plurality of variable amplitude and phase (VAP) adjusting arrangements
Implementation Method 3
The VAP adjusting arrangements may be configured to electronically adjust the amplitude and phase of the plurality of feed elements so as to electrically steer the user beams
Data Source
AI summary
A spacecraft includes an antenna reflector coupled with an antenna pointing mechanism (APM), a beam forming network including variable amplitude and phase (VAP) adjusting arrangements, a tracking feed that receives a beacon signal by way of the reflector, and an autotrack receiver that measures pointing errors of the reflector from the received beacon signal and outputs corresponding pointing errors to the APM controller and to a VAP element controller. The antenna reflector is illuminated by radiating feed elements configured as a phased array that produces, in a far field of the reflector, a set of user beams. The APM controller causes the APM to adjust the reflector pointing, at a frequency less than f1, to reduce the measured pointing errors. The VAP element controller adjusts pointing of the user beams by adjusting beam forming coefficients of the VAP adjusting arrangements at a second frequency greater than f1.