Antenna Pointing Error Correction via Laser Metrology
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Solution Overview
Problem
In radio astronomy, achieving high directional tracking precision for antennas observing higher frequency waves is hindered by structural and thermal deformations, which existing measurement methods struggle to correct accurately and efficiently, especially for sub-millimeter wave observations.
Innovation Solution
An antenna device with a frame structure group and displacement gauge system that measures and corrects pointing errors using metrology and instrumental error calculations, allowing for precise control of the antenna's drive commands to account for thermal and structural deformations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the aperture of the antenna is increased to improve observation efficiency and coverage, then the observation capability is enhanced, but the pointing precision deteriorates due to increased structural deformation and thermal effects
Solution Approach 1:
The patent introduces an intermediary measurement system consisting of a laser range finder and frame structure that indirectly measures the pointing error by detecting the position of the sub-reflector relative to the main reflector. This intermediary measurement approach allows for high-precision pointing error detection without being affected by the thermal and structural deformations of the large antenna aperture structure itself.
Solution Approach 2:
The patent replaces traditional mechanical measurement methods with an optical measurement system using laser range finders. This substitution eliminates the mechanical contact and associated errors, providing non-contact, high-precision measurement of the reflector positions and pointing errors even in the presence of structural deformations.
2Measurement precision
If optical instrumentation means using laser and optical detector is used to measure structural deformation, then measurement capability is provided, but measurement speed and precision deteriorate due to atmospheric fluctuations and processing delay
Solution Approach 1:
The patent extracts the measurement function from the main antenna structure by using a separate, stable frame structure as the reference. The laser range finder measures the position of the sub-reflector relative to this external frame rather than relative to the deforming antenna structure, thereby eliminating the harmful effects of atmospheric fluctuations and structural deformation on the measurement process.
3Stability of the object's composition
If mechanical instrumentation means with frame structure is used to measure pointing error, then structural stability is improved, but measurement precision deteriorates due to instrumental errors and inability to correct all error sources
Solution Approach 1:
The patent merges the advantages of both optical and mechanical approaches by combining the stable frame structure with laser-based measurement. The system uses the mechanically stable frame as a reference while employing optical laser range finders for actual measurement, thereby achieving both structural stability and high measurement precision while enabling real-time correction of pointing errors.
Data Source
AI summary
An antenna device includes: an antenna base portion; an antenna mount portion which is supported by the antenna base portion and rotated around an azimuth axis and which supports a main reflector with two struts; a frame structure group including a plurality of frame structures which are provided in the antenna base portion and the antenna mount portion, with six degrees of freedom restrained, respectively; a displacement gauge group which measures a displacement of the frame structure group; a metrology correction portion which calculates a pointing error of an antenna based on measured data of the displacement gauge group and calculates a metrology correction amount by removing an error amount arising depending on an azimuth angle from the calculated pointing error; and a control circuit which controls a driving of the antenna by correcting a drive command value of the antenna with the metrology correction amount.