Ka-Band Satcom Antenna Calibration for Aircraft Installation Bias
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Solution Overview
Problem
Existing methods for calibrating Ka-band Satcom antennas in the aeronautical field lack sufficient accuracy due to the large size and rectangular geometry of the antennas, which makes precise pointing challenging, especially when installed on aircraft cabins, leading to significant loss of gain if the antenna is not aligned within 0.2°.
Innovation Solution
A method that automatically measures and compensates for installation biases by receiving satellite signals at multiple aircraft orientations during calibration, using a geometric function to calculate theoretical antenna orientations and minimizing a criterion to determine bias values for accurate alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the antenna is installed on the aircraft cabin, then the antenna can be positioned away from the airfoil, but the installation accuracy deteriorates to one degree or worse
Solution Approach 1:
The patent applies preliminary action by performing calibration measurements at multiple predefined angle positions (n>1) before final antenna deployment. The system pre-determines bias values by measuring antenna orientation at each position and comparing with theoretical orientations calculated from inertial unit data, then uses these pre-determined biases to correct future pointing accuracy.
Solution Approach 2:
The patent replaces mechanical alignment methods with an automated electronic calibration system. Instead of relying on precise mechanical installation, the system uses automated measurements of antenna orientation at multiple positions, computational calculation of bias values, and electronic compensation to achieve sub-0.2° pointing accuracy despite mechanical installation tolerances of one degree or worse.
2Loss of energy
If the antenna pointing accuracy is required to be better than 0.2°, then the gain loss is minimized, but the installation and calibration complexity increases
Solution Approach 1:
The patent applies self-service by enabling the antenna system to automatically determine its own installation biases through the calibration process. The system autonomously performs measurements at multiple angle positions, calculates bias values from the measured versus theoretical orientations, and stores these biases for automatic compensation during operation, eliminating the need for external manual calibration procedures.
Solution Approach 2:
The patent implements feedback by continuously comparing measured antenna orientations with theoretical orientations calculated from inertial unit data and satellite position information. The system uses this feedback to determine bias values that minimize the difference between measured and expected orientations, then applies these biases to correct future pointing commands, ensuring accuracy better than 0.2° while minimizing gain loss.
3Measurement precision
If laser interferometry navigation equipment is used, then the antenna pointing accuracy can reach 0.1°, but the system cost and complexity increase significantly
Solution Approach 1:
The patent applies copying by creating a computational model of the antenna orientation system that replicates the functionality of expensive laser interferometry equipment. Instead of using physical laser interferometers, the system uses multiple angle position measurements and geometric calculations to generate equivalent pointing accuracy information, achieving 0.1° accuracy through software-based orientation determination rather than expensive optical hardware.
Solution Approach 2:
The patent changes the measurement parameters from continuous laser interferometry to discrete angle position measurements at n>1 predefined positions. By measuring antenna orientation at multiple discrete positions and using geometric functions to calculate theoretical orientations from inertial unit data (pitch, roll, heading), the system achieves high precision without requiring complex continuous measurement equipment.
Data Source
AI summary
Method and device for calibrating an antenna includes the following steps: define a number n of positions of angles for the aircraft situated in a calibration zone: measure the value of the orientation of the antenna for each position n, [#a(n), #a(n)]; define the theoretical orientation of the antenna [#a(n)*, #a(n)*] by taking account of the pitch value, of the roll value, of the yaw value (heading) for the aircraft for each position n, and of the orientation values of the satellite [#r(n), #r(n)]: [Aa(n)*, Ea(n)*]=F(H(n), P(n), R(n), ##, ##, #R, ##, Ar(n), Er(n)), where F is a chosen geometric function; define a criterion C: C=#(#a(n)−#a(n)*)2+(#a(n)−#a(n)*)2; minimize the value of the criterion C so as to determine the bias values (##, ##, #R, ##) from the values [Aa*(n), Ea*(n)] and use the said bias values to minimize the disparities between the measured angles and the theoretical angles.