Phased Array Antenna Calibration Through Geometric OTA Measurements
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Solution Overview
Problem
Phased array antennas in satellite communication systems face performance variations due to weather and environmental conditions, affecting gain, phase, and delay, necessitating effective calibration methods to maintain signal integrity.
Innovation Solution
A method and apparatus for calibrating antenna elements using over-the-air (OTA) measurements, involving geometric relationships and complex coupling ratios to determine phase and gain correction factors, and incorporating mutual coupling measurements for redundancy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional calibration methods are used, then calibration can be performed, but calibration accuracy deteriorates due to environmental variations affecting antenna elements
Solution Approach 1:
The system performs self-calibration by having antenna elements measure each other's performance characteristics through OTA measurements. The calibrated antenna elements serve as reference standards for calibrating uncalibrated elements, enabling the system to correct its own performance variations without external intervention.
Solution Approach 2:
The calibration process uses feedback from OTA measurements to determine correction factors. The measured performance characteristics of antenna elements are fed back to compute phase and gain correction factors, which are then applied to compensate for environmental variations and maintain calibration accuracy.
2Measurement precision
If more antenna elements are calibrated, then calibration coverage improves, but measurement complexity increases
Solution Approach 1:
The calibration process is segmented into stages where antenna elements are calibrated in groups. A subset of antenna elements is first calibrated using in-line measurements, then these calibrated elements are used to calibrate other elements through OTA measurements. This segmentation reduces the complexity of calibrating all elements simultaneously.
Solution Approach 2:
The calibrated antenna elements serve multiple functions: they act as reference standards for calibrating other elements, and their calibration results are used to determine correction factors for the entire array. This multi-functionality reduces the overall complexity by reusing calibrated elements throughout the calibration process.
Data Source
AI summary
A method of calibrating a phased array antenna is provided. The method includes performing a relative calibration of a subset of antenna elements of an antenna lattice relative to one another based on in-line calibration measurements between a calibration line and the subset of antenna elements to yield a calibrated subset of antenna elements; capturing a first OTA calibration measurement pair, wherein the first OTA calibration measurement pair comprises a first OTA calibration measurement associated with a particular geometric relationship, determining a complex coupling ratio associated with the particular geometric relationship based on the first OTA calibration measurement and the second OTA calibration measurement, capturing a second OTA calibration measurement pair associated with the particular geometric relationship, and determining, at least one of a phase correction factor or a gain correction factor between a complex gains of a pair of uncalibrated antenna elements.