Phased Array Passband Calibration Using Probe-to-Field Transforms
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Solution Overview
Problem
Phased array antennas in RF communication and radar systems face challenges with frequency-dependent distortion, particularly in electrically-steerable phased arrays, where calibration processes require frequent updates due to aging effects and temperature dependence, often necessitating downtime for far-field probe measurements.
Innovation Solution
A method for phased array passband calibration that eliminates the need for a far-field probe during subsequent calibrations by using a calibration probe and database of probe-to-far-field transforms to determine a calculated phased array passband response, allowing for repeated calibrations in the field without moving the far-field sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If far-field probe measurements are used for calibration, then measurement precision is improved, but loss of time increases due to system downtime and probe movement requirements
Solution Approach 1:
The patent creates a computational model that copies the far-field probe measurement capability, allowing calibration to be performed through calculations rather than physical probe measurements. The system stores measured passband responses and uses these to compute calibration parameters without requiring actual probe movements or system downtime.
Solution Approach 2:
The patent performs preliminary measurements to build a database of passband responses across different frequencies and steering angles. This pre-acquired data is then used for rapid calibration computations, eliminating the need for time-consuming probe measurements during actual calibration events.
2Measurement precision
If far-field probe measurements are used for calibration, then measurement precision is improved, but device complexity increases due to probe handling and positioning requirements
Solution Approach 1:
The patent replaces the physical far-field probe measurement system with a computational model that replicates its functionality. Instead of requiring complex probe positioning and handling equipment, the system uses stored measurements and mathematical computations to achieve the same calibration objectives with significantly reduced hardware complexity.
Solution Approach 2:
The patent introduces a computational model as an intermediary between the antenna array and the calibration process. This model uses pre-stored passband response data to compute calibration parameters, eliminating the need for direct physical probe measurements and the associated complex positioning and handling systems.
3Reliability
If frequent calibration cycles are performed to compensate for aging effects, then reliability is improved, but loss of time increases due to repeated calibration downtime
Solution Approach 1:
The patent performs comprehensive measurements in advance to build a database of passband responses across the full operating range of frequencies and steering angles. This pre-acquired data enables rapid calibration computations to be performed later without requiring time-consuming probe measurements, allowing frequent calibration cycles with minimal downtime.
Solution Approach 2:
The patent creates a computational model that copies the measurement capability, enabling rapid recalibration computations using stored data. This allows the system to perform frequent calibration cycles to compensate for aging effects without incurring the time penalty of repeated physical probe measurements.
4Manufacturing precision
If hardware costs are increased to limit distortions within the operating band, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent changes the approach from hardware-based distortion compensation to software-based computational compensation. Instead of using more complex or expensive hardware components to limit passband distortions, the system uses digital signal processing and computational models to characterize and compensate for distortions, achieving the same goal with lower hardware complexity.
Solution Approach 2:
The patent replaces hardware-based distortion control mechanisms with software-based computational methods. The system uses measured passband responses and mathematical models to compensate for distortions, substituting complex hardware solutions with simpler computational approaches that achieve the same level of passband control.
Data Source
AI summary
Systems and methods are provided for phased array passband calibration, which permits repeated calibration of the antenna system in the field without a moving far field sensor. An implementation includes an equalization filter coupled to a phased array feed; a calibration probe disposed to couple with an antenna array to transfer radio frequency (RF) energy; a database of probe-to-far-field (FF) transforms having a probe-to-FF transform for each of a plurality of incidence angles; a calibration component operable to: receive calibration probe measurements for a plurality of frequencies; and determine a calculated phased array passband response for at least a first incidence angle, based at least on the calibration probe measurements and a probe-to-FF transform for the first incidence angle; and a filter generation component operable to generate a tuning configuration for the equalization filter, based at least on the calculated phased array passband response.