Phased Antenna Array Calibration via Single-Element Transmission
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Solution Overview
Problem
Conventional aircraft surveillance systems face inaccuracies and inefficiencies due to insertion phase errors in phased antenna arrays, which require complex and time-consuming calibration processes that cannot be performed simultaneously with surveillance operations.
Innovation Solution
An active phased array antenna system with built-in calibration paths allows for the transmission of interrogation signals from a single antenna element at a time, enabling the calculation of phase calibration offsets and storage in a look-up table, thereby bypassing power amplifiers and low noise amplifiers during calibration, and using digital signal processing for accurate phase detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional calibration methods are used to correct insertion phase errors in phased antenna arrays, then measurement precision is improved, but calibration time increases significantly and cannot be performed simultaneously with surveillance operations
Solution Approach 1:
The calibration system allows calibration operations to proceed continuously without interrupting surveillance functions. The antenna array performs both calibration and surveillance operations simultaneously by using calibration signals that do not interfere with normal interrogation signals, eliminating the need to suspend surveillance during calibration.
Solution Approach 2:
The system uses its own antenna elements and signal processing capabilities to perform self-calibration. By transmitting calibration signals from one antenna element and receiving them at other elements, the system automatically determines phase offsets without requiring external calibration equipment or interrupting normal operations.
2Measurement precision
If complex calibration procedures are implemented to achieve accurate phase correction, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The antenna array system performs self-calibration using its own hardware resources. Each antenna element can transmit calibration signals and other elements receive them, allowing the system to automatically calculate phase offsets without requiring external calibration equipment, reducing overall system complexity.
Solution Approach 2:
The antenna elements serve multiple functions: they perform both surveillance operations (transmitting interrogation signals and receiving responses) and calibration operations (transmitting calibration signals and receiving them at other elements). This multi-functionality eliminates the need for separate calibration hardware, reducing device complexity.
3Measurement precision
If traditional calibration methods are used that require suspending surveillance operations, then measurement precision is improved, but productivity decreases
Solution Approach 1:
The system maintains continuous surveillance operations while performing calibration. Calibration signals are transmitted and received without interrupting the normal interrogation and response signal flow, ensuring that productivity is not compromised while achieving accurate calibration.
Solution Approach 2:
The calibration process is performed periodically or continuously in the background during normal surveillance operations. The system can update calibration data at appropriate intervals without stopping surveillance, maintaining both accuracy and productivity.
Data Source
AI summary
In accordance with one aspect of the present invention, a method is provided for calibrating an aircraft surveillance system for a protected aircraft. The system has a phased antenna array comprising antenna elements. The method comprises transmitting a first signal from a first antenna element in the array, and receiving the first signal at a third antenna element. The first signal may represent an interrogation signal transmitted in connection with a surveillance transmit sequence to locate potential intruding aircraft into a range of the protected aircraft. The method further includes transmitting a second signal from a second antenna element and receiving the second signal at the third antenna element. The method also includes calculating calibration information for the antenna array based on the first and second signals received at the third antenna element. During each transmit operation only a single antenna element transmits at one point in time.