Laser Tracking Near-Field Antenna Measurement
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Solution Overview
Problem
Existing near-field antenna measurement systems are costly and prone to errors due to mechanical oscillations and thermal drift, requiring expensive equipment and time-consuming calibration, which affects the accuracy of far-field data transformation.
Innovation Solution
A high-speed tracking laser-based system that synchronizes probe position data with RF measurements using a global positioning coordinate system defined by monuments, allowing for accurate near-field RF measurements without the need for expensive mechanical structures or advanced calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If expensive rigid equipment with precise position control is used, then measurement precision is improved, but device cost increases significantly
Solution Approach 1:
The patent replaces the mechanical position control system with an optical tracking system using a laser tracker. Instead of relying on expensive rigid mechanical structures with precise position control, the system uses a laser tracker to optically monitor and record the actual probe position in real-time, substituting mechanical precision requirements with optical measurement capabilities.
Solution Approach 2:
The patent creates a digital copy of the probe position through laser tracking. The laser tracker captures the actual position of the probe and stores this position data, creating a digital representation that can be used for post-processing corrections. This allows the system to work with less expensive mechanical structures while maintaining measurement accuracy through digital position recording and correction.
2Reliability
If calibration is performed periodically, then measurement reliability is improved, but loss of time increases due to calibration duration
Solution Approach 1:
The patent implements continuous position monitoring throughout the entire measurement process. The laser tracker continuously tracks the probe position from start to finish of each measurement, eliminating the need for separate calibration phases. This continuous tracking ensures position data is always available for corrections without requiring time-consuming periodic calibration interruptions.
Solution Approach 2:
The patent performs position recording continuously throughout the measurement process rather than calibrating beforehand. The laser tracker captures position data during the actual measurement, ensuring that position information is already available when needed for data correction, eliminating separate pre-calibration steps.
3Measurement precision
If calibration is performed in advance, then measurement precision is improved, but any variance in conditions between calibration and measurement causes inaccuracies
Solution Approach 1:
The patent maintains continuous position tracking throughout the entire measurement process, ensuring that position data is recorded under the exact same environmental conditions as the measurements themselves. This eliminates the condition variance problem by ensuring position and measurement data are collected simultaneously and continuously, rather than separating calibration from measurement in time.
4Device complexity
If simple phase correction is applied, then device complexity is reduced, but measurement precision deteriorates due to single pointing direction correction limitation
Solution Approach 1:
The patent implements a feedback mechanism where the laser tracker continuously monitors probe position and provides this position information back to the measurement system. This feedback loop enables the system to use actual position data for correcting far-field transformations, improving accuracy beyond simple phase correction while maintaining reasonable system complexity through post-processing applications.
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
This approach enables precise and cost-effective near-field RF measurements for a wide range of antennas, reducing errors and eliminating the need for costly equipment and time-consuming calibration processes, while maintaining high accuracy in transforming data to far-field patterns.
Implementation Method 1
The laser measures probe position by determining the time of flight of light
Data Source
AI summary
An Antenna measurement system incorporating high speed tracking laser-based global positioning capture synchronized with radio frequency (RF) measurements. A high speed tracking laser is used for collecting RF probe position data synchronously with corresponding near-field RF measurements. The probe may be moved across an arbitrary surface surrounding or adjacent to a device under test (DUT); however, it is not necessary for the probe position to be perfectly coincident with the surface, or any of the discrete points which make up the surface. Here, the probe position is determined relative to a global positioning coordinate system which is defined by a set of monuments which are in known positions relative to the global positioning coordinate system, and not the DUT. Any difference between the actual position of the probe, in the global position coordinate system, and a given one of the discrete measuring points, in the global position coordinate system, on the surface surrounding or adjacent to the DUT can be accounted for during post processing, thus eliminating the need for advanced or intermittent calibration to achieve precise near-field measurements.