Calibration Target with Diffuse Reflector for Antenna Array Positioning
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Solution Overview
Problem
The calibration of millimeter-wave imaging-antenna arrangements requires extremely high accuracy in the positioning of the calibration object relative to the antenna device, which is costly and difficult to achieve due to the need for precise measurement of the spacing distance and orientation, especially given the large number of transmitter/receiver units involved.
Innovation Solution
The method involves using a calibration object with a diffuse reflector that allows for rough initial positioning, with estimated coordinates being corrected numerically through image evaluation and optimization algorithms, such as gradient or genetic optimization methods, to determine the exact position and orientation of the calibration object, thereby improving measurement accuracy without the need for precise mechanical alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a metal plate positioned at a predetermined distance is used as the calibration object with traditional calibration methods, then the phase error can be controlled within 5°, but the accuracy of spacing distance measurement must be approximately 40 μm which requires very high mechanical costs
Solution Approach 1:
The patent replaces the mechanical positioning system with an optical evaluation system. Instead of using precision mechanical stages to achieve 40 μm spacing accuracy, the invention uses a camera to capture images of the calibration object and computationally determines the exact position. The diffuse reflector creates a characteristic image pattern that allows sub-pixel accuracy positioning through image processing, eliminating the need for expensive precision mechanical positioning equipment while maintaining the required 5° phase error control.
2Measurement precision
If the spacing distance between the calibration object and the antenna device is measured with very high accuracy (40 μm), then the phase error is controlled within 5°, but the mechanical costs increase significantly
Solution Approach 1:
The patent creates an optical copy (image) of the calibration object's position information. Instead of directly measuring the physical spacing distance with precision mechanical equipment, the system captures an optical image of the diffuse reflector and extracts position information from the image. This copying approach allows the determination of spacing distance with 40 μm accuracy through computational methods rather than direct mechanical measurement, significantly reducing the mechanical costs while achieving the required precision.
3Reliability
If traditional calibration methods are used requiring precise mechanical positioning, then accurate calibration data can be obtained, but the positioning complexity and mechanical requirements become extremely high
Solution Approach 1:
The patent substitutes complex mechanical positioning systems with a simplified optical imaging system. The diffuse reflector mounted on the calibration object creates a distinctive image pattern that can be captured by a standard camera. Image processing algorithms then automatically determine the position and orientation of the calibration object with high precision, eliminating the need for complex mechanical positioning mechanisms, precision stages, and associated control systems while maintaining calibration 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 reduces the mechanical costs associated with achieving high calibration accuracy by allowing for approximate initial positioning of the calibration object, enabling improved measurement accuracy and precise calibration of the antenna arrangement through iterative image evaluation and correction.
Implementation Method 1
the calibration object provides a diffuse reflector directed towards the antenna arrangement, wherein the diffuse reflector reflects in a diffuse manner signals which strike it
Data Source
AI summary
The system (1) is used for the automatic calibration of an imaging-antenna arrangement (2) using an evaluation unit (4). The antenna arrangement (2) transmits signals (6) and receives the signals (6′) reflected from a calibration object (3) of known shape. The calibration object (3, 31, 32) provides at least one diffuse reflector (8). In the evaluation method, position coordinates of the calibration object (3) are entered, and the following method steps are implemented after the measurement of the reflected signals (6′):i. Calculation of the reflections of the calibration object (3, 31, 32),ii. Calculation of calibration data,iii. Preparation of an image of the calibration object with the use of the calibration data,iv. Determination of corrected position coordinates by evaluating the image of the at least one diffuse reflector,v. Implementation of steps i. to iv. with corrected position coordinates.