Conformal Antenna Array Calibration for Aircraft Beam Pointing Errors
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Solution Overview
Problem
Conformal antenna arrays on aircrafts are susceptible to structural changes and deformations, leading to pointing errors, side lobe degradation, and reduced performance due to their integration with the aircraft's fuselage, which increases drag and fuel consumption.
Innovation Solution
A hybrid in-situ and signal of opportunity (SoOP) calibration method that uses cooperative satellites in direct line-of-sight with the antenna array to supplement an in-situ source for real-time beam steering and correction of phase errors, leveraging known satellite positions and aircraft localization systems to estimate and correct for mismatches and deformations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conformal antenna arrays are integrated with the aircraft fuselage to support multiple services, then drag and fuel consumption are reduced, but structural changes and deformations cause pointing errors and side lobe degradation
Solution Approach 1:
The patent implements a feedback mechanism by continuously monitoring the actual direction of arrival of calibration signals from satellites and comparing it with the expected direction based on satellite ephemeris data. This feedback loop enables real-time detection and correction of pointing errors caused by fuselage deformations, maintaining antenna performance despite structural changes.
Solution Approach 2:
The system dynamically adjusts antenna array parameters (phase and amplitude weights) based on measured deformations. By changing these parameters in real-time according to the detected structural changes, the system compensates for pointing errors and maintains optimal beam steering accuracy.
2Device complexity
If conformal antenna arrays are integrated with the aircraft fuselage, then the number of protruding antennae is reduced, but manufacturing and installation complexity increases
Solution Approach 1:
The patent implements a universal calibration system that can handle multiple antenna types and configurations through a single integrated approach. The calibration methodology is designed to be adaptable to different fuselage shapes and antenna arrangements, reducing the need for custom manufacturing and simplifying installation across various aircraft models.
3Measurement precision
If in-situ calibration sources are used alone, then calibration can be performed, but accuracy is insufficient due to limited baseline for error estimation
Solution Approach 1:
The patent merges two calibration approaches: in-situ calibration using on-board sources and external calibration using satellite signals. By combining these methods, the system leverages the known precise positions of satellites to establish an accurate baseline for error estimation, significantly improving calibration accuracy while maintaining system feasibility.
Data Source
AI summary
Hybrid in-situ and signal of opportunity (SoOP) calibration for antenna arrays is provided. Deployment of aircraft antennae is redesigned to support multiple services with shared physical elements that conform to the exterior of an aircraft to mitigate drag. Conformal arrays are, however, susceptible to structural changes in the fuselage that manifest as pointing errors and side lobe degradation. Embodiments provide an online calibration algorithm that leverages cooperative satellites in direct line-of-sight of a radio frequency (RF) device with an antenna array (e.g., an aircraft with a conformal antenna array) to optimally steer beams. These external calibration sources supplement an in-situ source mounted on a common platform with the antenna array (e.g., placed on the aircraft's tail). Models are established for potential sources of mismatch and the hybrid calibration method is demonstrated via simulations.