Radar Antenna Array Calibration for Cross-Coupling and Nodal Shift
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing radar systems face challenges in accurately calibrating for cross-coupling and gain/phase variations, particularly in large-scale MIMO systems where maintaining a nodal point is difficult or impossible, especially when mounted on robots or drones, or when angle calibration is desired in situ with the system assembled.
Innovation Solution
A radar calibration system that rotates transmitters and receivers in both azimuth and elevation, correcting for phase distortion and angle-of-arrival errors due to misalignment between the antenna array center and the rotation center, using a calibration module to calculate and correct for nodal displacement, and employing iterative least-squares methods to estimate and correct for channel and cross-coupling impairments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional calibration methods are used in large-scale MIMO radar systems, then the system structure is simpler, but the calibration accuracy deteriorates due to difficulty in maintaining nodal point and cross-coupling effects
Solution Approach 1:
The patent applies preliminary action by performing calibration measurements before the radar system is deployed in its final configuration. The calibration is done in a controlled environment where the antenna array can be positioned on a rotating platform, allowing accurate measurement of channel responses and cross-coupling effects before installation in the vehicle or robot where nodal point maintenance would be difficult.
Solution Approach 2:
The patent uses an intermediary approach by introducing a calibration-specific rotating platform and measurement setup that acts as a mediator between the radar system and the calibration process. This intermediary structure enables accurate nodal point maintenance during calibration without requiring the final application platform to have this capability.
2Adaptability or versatility
If the radar system is mounted on mobile platforms like robots or drones, then the system becomes more versatile, but maintaining nodal point for accurate calibration becomes difficult or impossible
Solution Approach 1:
The patent performs calibration measurements in advance, before the radar system is mounted on mobile platforms. This preliminary calibration captures the channel responses and cross-coupling characteristics when the system can be properly positioned on a stable rotating platform, storing this data for use during actual mobile operations where recalibration would be impractical.
Solution Approach 2:
The patent introduces dynamic elements by using a rotating platform during calibration that can dynamically adjust the antenna array orientation to maintain nodal point alignment, whereas the final mobile application is static in terms of calibration capability. The rotating mechanism provides the necessary dynamic adjustment capability temporarily during calibration.
3Ease of manufacture
If in situ calibration is performed with the system assembled, then the calibration process is simpler, but cross-coupling and gain/phase variations cannot be accurately corrected
Solution Approach 1:
The patent performs calibration measurements in advance in a controlled environment where the antenna array can be properly positioned and oriented on a rotating platform. This preliminary action captures accurate channel response data and cross-coupling characteristics before the system is finalized, enabling accurate correction of impairments even though the process is more complex than in-situ calibration.
Data Source
AI summary
A radar system with on-system calibration includes capabilities for radar detection and correction for system impairments to improve detection performance. The radar system is equipped with pluralities of transmit antennas and pluralities of receive antennas. The radar system uses a series of calibration measurements of a known object to estimate the system impairments. A correction is then applied to the beamforming weights to mitigate the effect of these impairments on radar detection. The estimation and correction requires no external measurement equipment and can be computed on the radar system itself.