Phased Array Antenna Self-Calibration for Mixed Tx/Rx Arrays
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Solution Overview
Problem
Conventional mutual coupling methods for phased array antennas are limited in their ability to calibrate large arrays without external equipment, fail to handle non-symmetrical mutual coupling, and are ineffective for antennas with mixed transmitter and receiver elements, leading to inaccuracies and complexity in self-calibration processes.
Innovation Solution
A computer-implemented technique using a processor and memory circuitry to build and solve a set of linear equations representing differences in real parameters between antenna elements, allowing for self-calibration by adjusting internal parameters to achieve equalized amplitude and phase across the array, utilizing a modified mutual coupling method that considers arbitrary couples of transmit and receive elements and reduces the number of unknowns through equal mutual coupling values in opposite couples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional mutual coupling methods are used for self-calibration, then calibration can be performed without external equipment, but the method fails when elements are non-transceivers or when mutual coupling is non-symmetrical
Solution Approach 1:
The patent applies asymmetry by removing the symmetry assumption from conventional MCM. The system now handles non-symmetrical mutual coupling coefficients (C_ij ≠ C_ji) and different excitation levels for transmit and receive elements, allowing calibration of mixed-mode antennas where some elements are transmitters only and others are receivers only.
Solution Approach 2:
The patent achieves universality by creating a calibration method that works for all antenna element types (transceivers, transmitters only, receivers only) and all mutual coupling scenarios (symmetrical and non-symmetrical). The unified mathematical framework using linear equations makes the method applicable to diverse phased array configurations without requiring different approaches for different antenna types.
2Device complexity
If conventional MCM assumes symmetrical mutual coupling for all elements, then the calibration process is simpler, but accuracy deteriorates when actual coupling is non-symmetrical
Solution Approach 1:
The patent changes the fundamental parameter assumption from symmetrical mutual coupling (C_ij = C_ji) to non-symmetrical mutual coupling (C_ij ≠ C_ji). This parameter change allows the system to accurately model real-world antenna interactions where coupling strength depends on both transmit and receive states, significantly improving calibration accuracy for mixed-mode antennas.
3Measurement precision
If calibration is performed using indoor near field range facilities, then accurate calibration tables can be generated, but transportation and facility requirements become prohibitive for large arrays
Solution Approach 1:
The patent implements self-service by enabling the phased array antenna to calibrate itself using its own elements as both transmitters and receivers. The antenna performs mutual coupling measurements internally without requiring external calibration equipment, near-field ranges, or transportation to specialized facilities, making the process autonomous and site-independent.
4Reliability
If dynamic algorithms are used to detect and bypass faulty elements in MCM, then faulty elements can be handled, but the system complexity and computational requirements increase significantly
Solution Approach 1:
The patent applies feedback by using the measured mutual coupling coefficients to automatically identify and isolate faulty elements. The system measures coupling between all element pairs, detects anomalies in the measured values that indicate faults, and excludes those elements from the calibration calculations, maintaining reliability without requiring complex pre-programmed fault detection algorithms.
Data Source
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AI summary
A computer implemented method for self-calibration of a Phased Array Antenna (PAA) having an array of N antenna elements. Each element operates as a transmit antenna element and/or as a receive antenna element. The method includes building an overdetermined system of linear equations presenting different couples of antenna elements. Each equation expressing a difference between a value of a real parameter, determined for a specific couple, and a sum of unknowns including unknown calibrated parameters of the antenna elements forming the specific couple, Next, solving the system of equations for obtaining a solution in the form of values of corrections to be applied to corresponding antenna elements in the array, in order to reduce the difference in each of the equations by bringing internal parameters of the antenna elements in a specific couple closer to their respective unknown calibrated parameters. Each couple being formed from a transmit antenna element and a receive antenna element positioned at an arbitrary distance from one another in the PAA array.