Near-Field Phased Array Calibration Without Anechoic Chambers
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Solution Overview
Problem
Phased array systems face performance degradation due to manufacturing errors, temperature variations, and RF component aging, requiring calibration to maintain performance, but traditional calibration methods necessitate an anechoic chamber and complex positioning mechanisms, making them impractical for field deployment.
Innovation Solution
A method for calibrating a receiving phased array in the near field using existing hardware components without dismounting the array, employing bistatic radar techniques and auto-calibration to correct for spherical aberration and multi-path interference, allowing for calibration without precise positioning or anechoic chambers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional calibration methods are used, then calibration accuracy is improved, but device complexity and operational difficulty increase due to requiring anechoic chambers and precise positioning mechanisms
Solution Approach 1:
The patent extracts the calibration function from the complex traditional system (anechoic chamber + positioning mechanisms) and implements it using only the phased array's existing receiving elements. The receiving elements serve dual purposes: normal operation and self-calibration, eliminating the need for external calibration infrastructure.
Solution Approach 2:
The phased array performs self-calibration using its own receiving elements to measure and correct errors. The system calibrates itself by having receiving elements sequentially measure signals from a single active transmitting element, eliminating the need for external calibration equipment and operators.
2Measurement precision
If traditional calibration methods are used, then calibration accuracy is improved, but ease of operation deteriorates due to requiring dismounting the array and complex positioning
Solution Approach 1:
The patent performs preliminary error measurement by having each receiving element sequentially measure the signal from a single active transmitting element before full operation. This preliminary measurement phase captures trace length and gain errors, which are then corrected to enable accurate calibration during normal operation.
Solution Approach 2:
Instead of using external equipment to measure the phased array, the patent inverts the approach by using the phased array's own receiving elements to measure and characterize its transmitting elements. This self-measurement approach simplifies operation by eliminating external calibration equipment.
3Reliability
If manufacturing tolerances and component aging are considered, then reliability is improved through calibration, but productivity decreases due to calibration time requirements
Solution Approach 1:
The patent enables continuous calibration by integrating the calibration process into normal operation. The same receiving elements used for calibration are immediately used for operational signal reception, and the calibration corrections are applied continuously to maintain accuracy over time despite component aging.
Solution Approach 2:
The patent changes the operational parameters by activating only one transmitting element at a time during calibration, rather than all elements simultaneously. This parameter change simplifies the calibration process and reduces the time required while maintaining accuracy through sequential measurement of each element's characteristics.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate calibration of phased arrays in the near field, correcting for range and phase mismatches, and improving signal-to-noise ratio, thus enhancing the performance and practicality of phased array systems in field applications.
Implementation Method 1
transmitting a plurality of electromagnetic signals from the transmitting antenna towards the phased array
Implementation Method 2
each of the plurality of receiving antennas to receive the electromagnetic signal
Data Source
AI summary
An already deployed phased array can be calibrated in the near field without the need for an anechoic chamber or complex positioning mechanisms. Calibration includes positioning a transmitting antenna in the near field in front of the receiving antennas and generating range profiles while the transmitting antenna is positioned at various locations. The range profiles are utilized to produce various defined vectors that are then used in calculations that output a coupling calibration matrix and two vectors that compensate for receiver channel length and gain differences. The coupling calibration matrix and the vectors are input into the processing unit of the phased array in order to calibrate the receiving channels relative to each other.