Self-Calibrating Conformal Phased Array Flexure Compensation
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Solution Overview
Problem
Conformal phased arrays on airborne platforms face continuous flexure issues, leading to degraded beam patterns, with existing mechanical and RF calibration methods being costly, complex, and limited in precision, especially for in-flight calibration.
Innovation Solution
A self-calibrating system using embedded calibration transmit/receive elements with small monopole antennas to track physical displacement, allowing real-time flexure estimation and adaptation of beam-pointing algorithms, enabling increased array performance by maximizing gain and minimizing sidelobe levels and beamwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mechanical sensors are embedded in the array to measure strain and movement, then measurement capability is improved, but device complexity and manufacturing difficulty increase significantly
Solution Approach 1:
The patent replaces mechanical strain sensors with electromagnetic field-based measurement. Calibration elements transmit electromagnetic signals that are received by array elements, and phase changes in these signals indicate element position changes due to flexure. This eliminates the need for mechanical sensors and their complex integration into the array substrate.
Solution Approach 2:
The array elements themselves serve dual purposes: they are both operational antenna elements and calibration measurement receivers. The calibration elements transmit signals that are received by the array elements, allowing the array to self-calibrate without external measurement equipment. This self-service approach reduces system complexity while maintaining measurement capability.
2Adaptability or versatility
If external antennas are used to measure beam patterns, then calibration capability is improved, but measurement precision and adaptability deteriorate due to limited mounting positions
Solution Approach 1:
Instead of using external antennas to measure beam patterns and infer element positions, the patent inverts the approach by having calibration elements transmit signals directly to the array elements. The phase of received signals provides direct measurement of element position changes, eliminating the need for external measurement positions and achieving higher precision through direct electromagnetic coupling.
Solution Approach 2:
The calibration elements serve multiple functions: they transmit calibration signals to enable self-calibration, and their signals are received by all array elements for position measurement. This multi-functional approach allows the system to perform calibration without requiring separate external measurement equipment or specific mounting positions, thereby improving both adaptability and precision.
3Manufacturing precision
If mechanical calibration approach is used, then initial calibration is achieved, but the system drifts out of calibration over time without feedback from actual beam pattern
Solution Approach 1:
The patent implements continuous feedback calibration by having calibration elements periodically transmit signals that are received by array elements. The measured phase changes provide real-time feedback on element position drift, allowing the system to continuously update calibration parameters and maintain accuracy over time. This feedback mechanism prevents drift by constantly monitoring and correcting element positions based on actual electromagnetic signal characteristics rather than relying on initial mechanical calibration data.
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
The system allows for precise, real-time flexure estimation and continuous calibration, enhancing array performance by maximizing gain and minimizing sidelobe levels and beamwidth, while being flexible and adaptable to various array layouts and frequencies.
Implementation Method 1
each of the calibration transmit/receive elements transmit a tone using a small antenna; and wherein the other calibration transmit/receive elements receive the tone using small antennas
Data Source
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AI summary
A system and method for a self calibrating conformal phased array are disclosed involving a plurality of transmit/receive elements; a plurality of embedded, calibration transmit/receive elements scattered across the array; and at least one back-end processor. The calibration transmit/receive elements are used to track any physical calibration transmit/receive element's relative position change caused by array flexure. In one or more embodiments, each of the calibration transmit/receive elements transmit a tone using a small antenna, and the other calibration transmit/receive elements receive the tone using small antennas. The calibration transmit/receive elements that receive the tone measure the phase of the received tone. At least one back-end processor uses the measured phases to determine differential phases from a phase calibration table. Also, at least one back-end processor uses the differential phases to compute a change in apparent location of each transmitting calibration transmit/receive element.