Phased Array Antenna Calibration Without Slewing for Pointing Error Correction
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Solution Overview
Problem
Conventional methods for calibrating spacecraft antennas in orbit are time-consuming due to the need for slewing the antenna during beam cuts, which is inefficient and not suitable for quickly correcting fixed alignment errors.
Innovation Solution
A method utilizing a two-dimensional linear fit phase tilt to estimate and correct azimuth, elevation, and yaw fixed errors in phase array antennas without slewing the antenna, using measurements from multiple locations and orientations to generate a reference tilt matrix and adjust the antenna's pointing errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional antenna beam cuts with slewing are used for calibration, then alignment error correction can be performed, but the calibration process becomes time-consuming
Solution Approach 1:
The patent replaces the mechanical slewing operation with a computational approach. Instead of physically moving the antenna to perform beam cuts, the system uses signal processing and mathematical models to determine alignment errors from measurements taken at fixed antenna positions. This substitution of mechanical action with computational analysis eliminates the time-consuming slewing process while maintaining calibration accuracy.
Solution Approach 2:
The patent performs preliminary measurements and calculations to establish alignment error corrections before actual operation. By collecting signal measurements at multiple fixed positions and pre-computing the alignment error corrections, the system prepares calibration data in advance, eliminating the need for time-consuming real-time slewing during operational calibration.
2Measurement precision
If multiple measurements are taken at different locations to improve calibration accuracy, then fixed alignment errors can be better corrected, but the calibration process becomes more complex
Solution Approach 1:
The patent changes the parameters used for calibration by utilizing signal measurements taken at multiple fixed antenna positions rather than requiring mechanical movement. By varying the measurement parameters (signal strength, phase, direction of arrival) at different fixed locations and using mathematical models to extract alignment errors, the system achieves accurate calibration without complex mechanical slewing operations.
Data Source
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AI summary
A method for calibrating an antenna includes receiving a plurality of signals transmitted from an antenna on a spacecraft. The antenna includes a plurality of phase array elements. The method also includes determining a phase tilt of the phase array elements based at least partially upon the signals. The method also includes removing a first portion from the determined phase tilt. The first portion is caused by a first location of the spacecraft, a first attitude of the spacecraft, or both. The method also includes estimating the phase tilt of the phase array elements after the first portion is removed. The method also includes generating a reference tilt matrix for the phase array elements. The method also includes comparing the estimated phase tilt to the reference tilt matrix. The method also includes determining a pointing error of the antenna based at least partially upon the comparison.