Phased Array Antenna Calibration Using Absorptive Lining
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Solution Overview
Problem
Phased array antennas face challenges in efficient testing and calibration due to the time-consuming nature of near-field testing and the inaccuracies and high costs associated with far-field testing, particularly in obtaining accurate phase information and the need for large testing chambers.
Innovation Solution
A test apparatus and method that uses a smaller chamber with an absorptive lining, an adjustable platform, and a probe to measure electromagnetic radiation, allowing for calibration of phased array devices by dividing elements into sub-arrays and determining an excitation matrix to calculate a far-field antenna pattern, enabling calibration without a large anechoic chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If near-field testing is performed by moving a probe from one antenna element to the next, then per-element amplitude and phase measurements can be obtained, but the movement of the probe causes substantial delays for each element, consuming significant amounts of time for large arrays of elements
Solution Approach 1:
The patent divides the phased array elements into multiple sub-arrays, where each sub-array is tested independently. This segmentation allows parallel processing of different sub-arrays, significantly reducing the total calibration time compared to sequential element-by-element testing, while still maintaining per-element measurement capability through the sub-array structure
Solution Approach 2:
The patent combines measurements from multiple sub-arrays to obtain complete per-element calibration data. By merging the results from different sub-array measurements, the system achieves comprehensive element-level accuracy without requiring time-consuming individual element testing, thus resolving the contradiction between measurement precision and time consumption
2Area of stationary object
If far-field testing is performed with a probe that is far from the antenna, then a smaller chamber can be used, but phase information is difficult to measure accurately and it can be difficult to obtain per-element information
Solution Approach 1:
The patent introduces an absorptive lining as an intermediary between the antenna array and the probe in the testing chamber. This lining absorbs scattered electromagnetic radiation, creating a controlled environment that enables accurate phase measurements even at reduced distances, effectively mediating between the need for small chamber size and the requirement for measurement precision
Solution Approach 2:
The patent changes the electromagnetic environment parameters by introducing absorptive materials that modify the reflection and scattering characteristics. This parameter change allows the system to achieve far-field like measurement conditions at near-field distances, enabling accurate phase and per-element information extraction without requiring large chamber volumes
3Measurement precision
If far-field testing is performed with a probe that is far from the antenna, then measurements can be taken, but large testing chambers are needed to provide far-field measurements for many frequency ranges, making them expensive and unsuitable for calibration in the field
Solution Approach 1:
The patent modifies the testing environment parameters by introducing absorptive linings that create electromagnetic conditions equivalent to far-field testing at much closer distances. This parameter change eliminates the need for large, expensive anechoic chambers while maintaining measurement accuracy, making the system suitable for field calibration applications
Solution Approach 2:
The patent creates a simplified copy of far-field testing conditions using absorptive materials and sub-array techniques. Instead of requiring actual far-field distances, the system replicates the essential measurement characteristics of far-field testing in a compact chamber, reducing complexity and cost while preserving measurement accuracy
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 allows for rapid and accurate calibration of phased array antennas, reducing calibration time and costs, and enabling field deployment without the need for specialized equipment, while improving the gain and steering of radiation patterns.
Implementation Method 1
a lining, the lining being made from a material that is absorptive to radiation at a test wavelength
Implementation Method 2
A probe is positioned at a second side of the chamber, opposite to the first side of the chamber, that measures electromagnetic radiation from the device under test
Data Source
AI summary
Testing apparatuses, and methods for using such apparatuses to calibrate and test an antenna, include a chamber that includes a lining, the lining being made from a material that is absorptive to radiation at a test wavelength. An adjustable platform is positioned at a first side of the chamber, the adjustable platform being rotatable to change an orientation of a device under test. A probe is positioned at a second side of the chamber, opposite to the first side of the chamber, that measures electromagnetic radiation from the device under test. A vector network analyzer communicates with the device under test and the probe to determine calibration information for the device under test.